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Torsades de pointes

2025-06-20T15:45:57Z

2601:642:C301:2730:B1AA:9310:CFA0:A058: ce

{{Short description|Type of abnormal heart rhythm}}
{{Infobox medical condition (new)
| name = ''Torsades de pointes''
| image = Torsades de Pointes TdP.png
| caption = 12-lead ECG of ''torsades de pointes'' (TdP) in a 56-year-old white female with [[hypokalemia|low blood potassium]] (2.4 mmol/L) and [[hypomagnesemia|low blood magnesium]] (1.6 mg/dL)
| field = [[Cardiology]]
| pronounce =
| synonyms = Torsade(s)
| symptoms =
| complications = [[Cardiac arrest]]
| onset =
| duration =
| types =
| causes = [[Heredity|Hereditary]], certain drugs, electrolyte disorders which cause [[Long QT syndrome|increased QT interval]]
| risks = Medications, hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, heart failure, left ventricular hypertrophy, hypothermia, subarachnoid hemorrhage, hypothyroidism
| diagnosis =
| differential =
| prevention =
| treatment =
| medication =
| prognosis =
| frequency =
| deaths = ~5% of 300,000 sudden cardiac deaths in the US<ref>{{Cite journal |date=2021-04-03 |title=Torsade de Pointes: Overview, Pathophysiology, Etiology of Torsade |url=https://emedicine.medscape.com/article/1950863-overview}}</ref>
}}

'''''Torsades de pointes''', '''torsade de pointes''''' or '''''torsades des pointes''''' ('''TdP'''; also called '''''torsades''''') ({{IPAc-en|t|ɔːr|ˌ|s|ɑː|d|_|d|ə|_|ˈ|p|w|ã|t}},<ref>{{cite web |url=https://www.lexico.com/definition/torsade_de_pointes |archive-url=https://web.archive.org/web/20200814132946/https://www.lexico.com/definition/torsade_de_pointes |url-status=dead |archive-date=August 14, 2020 |title = TORSADE DE POINTES {{!}} Meaning & Definition for UK English {{!}} Lexico.com}}</ref> {{IPA|fr|tɔʁsad də pwɛ̃t̪|lang}}, translated as "twisting of peaks") is a specific type of [[abnormal heart rhythm]] that can lead to [[sudden cardiac death]]. It is a polymorphic [[ventricular tachycardia]] that exhibits distinct characteristics on the [[electrocardiogram]] (ECG). It was described by French physician [[François Dessertenne]] in 1966.<ref>{{cite journal |last1=Dessertenne |first1=F. |author-link=François Dessertenne |title=La tachycardie ventriculaire a deux foyers opposes variables |language=fr |others=Prepared by Rahel Farhad |journal=Archives des maladies du coeur et des vaisseaux |volume=59 |issue=2 |pages=263–272 |year=1966 |pmid=4956181 |issn=0003-9683}}</ref> Prolongation of the [[QT interval]] can increase a person's risk of developing this abnormal heart rhythm, occurring in between 1% and 10% of patients who receive QT-prolonging antiarrhythmic drugs.<ref>{{Cite journal |doi=10.1097/CCM.0b013e318232db4a |title=High prevalence of corrected QT interval prolongation in acutely ill patients is associated with mortality |year=2012 |last1=Pickham |first1=David |last2=Helfenbein |first2=Eric |last3=Shinn |first3=Julie A. |last4=Chan |first4=Garrett |last5=Funk |first5=Marjorie |last6=Weinacker |first6=Ann |last7=Liu |first7=Jia-Ni |last8=Drew |first8=Barbara J. |journal=Critical Care Medicine |volume=40 |issue=2|pages=394–399 |pmid=22001585 |s2cid=27017787}}</ref>

== Signs and symptoms ==
Most episodes will revert spontaneously to a normal [[sinus rhythm]].<ref>{{Cite journal |doi = 10.1186/s40560-018-0329-1|pmid = 30214811|pmc = 6131849|title = Late presentation of Torsades de Pointes related to fluoxetine following a multiple drug overdose|journal = Journal of Intensive Care|volume = 6|year = 2018|last1 = Groot|first1 = Jan Albert Nicolaas|last2 = Ten Bokum|first2 = Leonore|last3 = Van Den Oever|first3 = Hubertus Laurentius Antonius|pages = 59 | doi-access=free }}</ref> Symptoms and consequences include [[palpitation]]s, [[dizziness]], [[presyncope|lightheadedness]] (during shorter episodes), [[syncope (medicine)|fainting]] (during longer episodes), and [[sudden cardiac death]].{{citation needed|date=February 2021}}

== Causes ==
Torsades occurs as both an inherited (linked to at least 17 genes)<ref>{{Cite journal |doi = 10.1016/j.ipej.2018.07.007|pmid = 30036649 |pmc = 6198685 |title = Genotype and clinical characteristics of congenital long QT syndrome in Thailand |journal = Indian Pacing and Electrophysiology Journal |volume = 18 |issue = 5 |pages = 165–171 |year = 2018 |last1 = Saprungruang |first1 = Ankavipar |last2 = Khongphatthanayothin |first2 = Apichai |last3 = Mauleekoonphairoj |first3 = John |last4 = Wandee |first4 = Pharawee |last5 = Kanjanauthai |first5 = Supaluck |last6 = Bhuiyan |first6 = Zahurul A. |last7 = Wilde |first7 = Arthur A. M. |last8 = Poovorawan |first8 = Yong}}</ref> and as an acquired form caused most often by drugs and/or electrolyte disorders that cause excessive lengthening of the QT interval.<ref>{{Cite journal | url=http://www.onlinejacc.org/content/67/13/1639 |doi = 10.1016/j.jacc.2015.12.063 |pmid = 27150690 |title = Predicting the Unpredictable |journal = Journal of the American College of Cardiology |volume = 67 |issue = 13 |pages = 1639–1650 |year = 2016 |last1 = Schwartz |first1 = Peter J. |last2 = Woosley |first2 = Raymond L.|s2cid = 35723658 |doi-access = }}</ref>

Common causes for torsades de pointes include drug-induced QT prolongation and, less often [[diarrhea]], [[hypomagnesemia|low serum magnesium]], and [[hypokalemia|low serum potassium]] or congenital long QT syndrome. It can be seen in malnourished individuals and chronic [[alcoholism|alcoholics]], due to a deficiency in potassium and/or magnesium. Certain drugs and combinations of drugs resulting in [[drug interactions]] are common contributors to torsades de pointes risk. [[Drug-induced QT prolongation|QT-prolonging medication]]s such as [[clarithromycin]], [[levofloxacin]], or [[haloperidol]], when taken concurrently with [[cytochrome P450]] inhibitors, such as [[fluoxetine]], [[cimetidine]], or particular foods including [[Grapefruit drug interactions|grapefruit]], can result in higher-than-normal levels of medications that prolong the QT interval in the bloodstream and therefore increase a person's risk of developing torsades de pointes. A TdP cardiac event precipitated by [[loperamide]] has been reported (although the dose was well beyond the therapeutic range of the medication).<ref name="Loperamide Induced Torsades de Pointes: A Case Report and Review of the Literature">{{cite journal |last1=Mukarram |first1=O. |last2=Hindi |first2=Y. |last3=Catalasan |first3=G. |last4=Ward |first4=J. |title=Loperamide Induced Torsades de Pointes: A Case Report and Review of the Literature |journal=Case Reports in Medicine |date=2016 |volume=2016 |pages=1–3 |doi=10.1155/2016/4061980 |pmid=26989420 |pmc=4775784|doi-access=free }}</ref>

=== Medications as causes ===
Knowledge that TdP may occur in patients taking certain prescription drugs has been both a major liability and a reason for the removal of 14 medications from the marketplace.<ref>{{Cite journal|doi = 10.1016/j.jacc.2010.01.001|title = Prevention of Torsade de Pointes in Hospital Settings|year = 2010|last1 = Drew|first1 = Barbara J.|last2 = Ackerman|first2 = Michael J.|last3 = Funk|first3 = Marjorie|last4 = Gibler|first4 = W. Brian|last5 = Kligfield|first5 = Paul|last6 = Menon|first6 = Venu|last7 = Philippides|first7 = George J.|last8 = Roden|first8 = Dan M.|last9 = Zareba|first9 = Wojciech|author10 = American Heart Association Acute Cardiac Care Committee of the Council on Clinical Cardiology|author11 = Council on Cardiovascular Nursing|author12 = American College of Cardiology Foundation|journal = Journal of the American College of Cardiology|volume = 55|issue = 9|pages = 934–947|pmid = 20185054|pmc = 3057430}}</ref> Forty-nine drugs known to cause TdP and another 170 that are known to prolong QT remain on the market because the drugs provide medical benefit and the risk of TdP can be managed and mitigated by instructions in the drug label.<ref>Woosley, R. L., Heise, C. W., Gallo, T., Tate, J., Woosley, D., and K. A. Romero. www.CredibleMeds.org, QTdrugs List, Accessed 9 June 2019, AZCERT, Inc. 1822 Innovation Park Dr., Oro Valley, AZ 85755.</ref><ref name=Champeroux/> Examples of compounds linked to clinical observations of TdP include [[amiodarone]], most [[fluoroquinolone]]s, [[methadone]], [[Lithium (medication)|lithium]], [[chloroquine]], [[erythromycin]], [[azithromycin]], [[pimozide]], and [[phenothiazines]].<ref name=Champeroux>{{Cite journal|pmc = 1576014|year = 2005|last1 = Champeroux|first1 = P.|last2 = Viaud|first2 = K.|last3 = El Amrani|first3 = A. I.|last4 = Fowler|first4 = J. S.|last5 = Martel|first5 = E.|last6 = Le Guennec|first6 = J. Y.|last7 = Richard|first7 = S.|title = Prediction of the risk of Torsade de Pointes using the model of isolated canine Purkinje fibres|journal = British Journal of Pharmacology|volume = 144|issue = 3|pages = 376–385|doi = 10.1038/sj.bjp.0706070|pmid = 15655517}}</ref> The [[Antiemetic|anti-emetic]] agent [[ondansetron]] may also increase the risk of developing TdP.<ref>{{Cite book|title=Davis's drug guide for nurses|last=Vallerand, April Hazard|others=Sanoski, Cynthia A.,, Deglin, Judith Hopfer, 1950-|isbn=978-0-8036-4085-6|edition=Fourteenth|location=Philadelphia|oclc=881473728|date = 2014-06-05}}</ref> It has also been shown as a side effect of certain anti-arrhythmic medications, such as [[sotalol]], [[procainamide]], [[quinidine]], [[ibutilide]], and [[dofetilide]].<ref name="pmid10907968">{{cite journal |title=Dofetilide, a New Class III Antiarrhythmic Agent |journal=Pharmacotherapy |volume=20 |issue=7 |pages=776–86 |date=July 2000 |pmid=10907968 |doi= 10.1592/phco.20.9.776.35208 |author1=Lenz T. L. |author2=Hilleman D. E. |s2cid=19897963 }}</ref> In one example, the gastrokinetic drug [[cisapride]] (Propulsid) was withdrawn from the US market in 2000 after it was linked to deaths caused by long QT syndrome-induced torsades de pointes. This effect can be directly linked to QT prolongation mediated predominantly by inhibition of the [[HERG|hERG channel]] and, in some cases, augmentation of the late [[sodium channel]].<ref>{{Cite journal|pmc = 4101031|year = 2014|last1 = Yang|first1 = T.|last2 = Chun|first2 = Y. W.|last3 = Stroud|first3 = D. M.|last4 = Mosley|first4 = J. D.|last5 = Knollmann|first5 = B. C.|last6 = Hong|first6 = C.|last7 = Roden|first7 = D. M.|title = Screening for Acute IKr Block is Insufficient to Detect Torsades de Pointes Liability: Role of Late Sodium Current|journal = Circulation|volume = 130|issue = 3|pages = 224–234|doi = 10.1161/CIRCULATIONAHA.113.007765|pmid = 24895457}}</ref>

== Risk factors ==
[[File:Torsades converted by AICD ECG strip Lead II.JPG|thumb|300px|Lead II [[electrocardiogram|ECG]] showing a TdP patient being shocked by an [[implantable cardioverter-defibrillator]] back to their baseline [[cardiac rhythm]]]]
The following is a partial list of factors associated with an increased tendency towards developing torsades de pointes:<ref>[https://crediblemeds.org/ndfa-list/ Clinical Factors Associated with Prolonged QTc and/or TdP] {{Webarchive|url=https://web.archive.org/web/20200816020705/https://www.crediblemeds.org/ndfa-list/ |date=2020-08-16 }}, CredibleMeds.org, accessed 8 June 2019.</ref>
* [[Medications]]
* [[Hypokalemia]] (low serum potassium)
* [[Hypomagnesemia]] (low serum magnesium)
* [[Hypocalcemia]] (low serum calcium)
* [[Bradycardia]] (slow heartbeat)
* [[Heart failure]]
* [[Left ventricular hypertrophy]]
* [[Hypothermia]]
* [[Subarachnoid hemorrhage]]
* [[Hypothyroidism]]

== Pathophysiology ==
The action potential of cardiac muscles can be broken down into five phases:{{citation needed|date=February 2021}}
* '''Phase 0:''' Sodium channels open, resulting in the entrance of Na+ into the cells; this results in the depolarization of the cardiac muscles.
* '''Phase 1:''' Sodium channels close; this stops depolarization. Potassium channels open, leading to an outward current of K+ out of the cells.
* '''Phase 2:''' Potassium channels remain open (outward current of K+), and calcium channels now also open (inward current of Ca++), resulting in a plateau state.
* '''Phase 3:''' Calcium channels close (inward Ca++ stops), but potassium channels are still open (outward K+ current); this persists until the cells gain back normal polarization (repolarization achieved). Please note that phase 0 leads to a net gain of Na+, while phases 1–3 lead to a net loss of K+. This imbalance is corrected by the Na+/K+-ATPase channel that pumps K+ into the cell and sodium out of the cell; this does not change polarization of the cells, but does restore ionic content to its initial state.
* '''Phase 4:''' Exciting triggers (''e.g.,'' sinus node) will cause minor depolarization in the cells; this will result in increasing permeability of sodium channels, which trigger the opening of sodium channels.

Repolarization of the cardiomyocytes occurs in phases 1–3 and is caused predominantly by the outward movement of potassium ions. In Torsades de pointes, however, the repolarization is prolonged; this can be due to electrolyte disturbances (hypokalemia, hypomagnesemia, hypocalcemia), bradycardia, certain drugs (disopyramide, sotalol, amiodarone, amitriptyline, [[chlorpromazine]], erythromycin) and/or congenital syndromes.<ref>{{Cite book|title=Davidson's Principles and Practice of Medicine|edition=21st|last=Davidson|first=Sir Stanley|publisher=Elsevier|year=2010|isbn=978-0-7020-3084-0|editor1-last=Colledge|editor1-first=Nicki|editor2-last=Walker|editor2-first=Brian|editor3-last=Ralston|editor3-first=Stuart|location=United Kingdom|pages=568}}</ref>

The prolongation of repolarisation may result in subsequent activation of an inward depolarisation current, known as an [[Afterdepolarization|early after-depolarisation]], which may promote triggered activity.<ref name="Yap 1363–1372">{{Cite journal|last1=Yap|first1=Yee Guan|last2=Camm|first2=A John|date=2017-01-17|title=Drug induced QT prolongation and torsades de pointes|journal=Heart|volume=89|issue=11|pages=1363–1372|issn=1355-6037|pmc=1767957|pmid=14594906|doi=10.1136/heart.89.11.1363}}</ref> Re-entry, due to a dispersion of refractory periods, is also possible;<ref>{{Cite journal|last1=Napolitano|first1=C.|last2=Priori|first2=S. G.|last3=Schwartz|first3=P. J.|date=1994-01-01|title=Torsade de pointes. Mechanisms and management|journal=Drugs|volume=47|issue=1|pages=51–65|issn=0012-6667|pmid=7510621|doi=10.2165/00003495-199447010-00004|s2cid=1153199}}</ref> this is because M Cells (found in the mid-myocardial layer) show a more prolonged repolarization phase in response to potassium blockage than other cells. In turn, this produces a zone of functional refractoriness (inability to depolarize) in the mid-myocardial layer.<ref name="Yap 1363–1372"/> When a new action potential is generated, the mid-myocardial layer will remain in a refractory period, but the surrounding tissue will depolarize. As soon as the mid-myocardial layer is no longer in a refractory period, excitation from nearby tissue will cause a retrograde current and a reentry circuit that will result in a positive chronotropic cycle, leading to tachycardia.{{citation needed|date=February 2021}}

== Diagnosis ==
The ECG tracing in torsades demonstrates a ''polymorphic ventricular tachycardia'' with a characteristic illusion of a twisting of the QRS complex around the isoelectric baseline (peaks, which are at first pointing up, appear to be pointing down for subsequent "beats" when looking at ECG traces of the "heartbeat"). It is hemodynamically unstable and causes a sudden drop in arterial blood pressure, leading to dizziness and [[Syncope (medicine)|fainting]]. Depending on their cause, most individual episodes of torsades de pointes revert to normal sinus rhythm within a few seconds; however, episodes may also persist and possibly degenerate into [[ventricular fibrillation]], leading to sudden death in the absence of prompt medical intervention. Torsades de pointes is associated with [[long QT syndrome]], a condition whereby prolonged QT intervals are visible on an ECG. Long QT intervals predispose the patient to an {{visible anchor|R-on-T phenomenon}}, wherein the R-wave, representing ventricular depolarization, occurs during the relative refractory period at the end of repolarization (represented by the latter half of the T-wave). An R-on-T can initiate torsades. Sometimes, pathologic [[T-U wave]]s may be seen in the ECG before the initiation of torsades.<ref name=pmc>{{Cite journal | last1 = John | first1 = J. | last2 = Amley | first2 = X. | last3 = Bombino | first3 = G. | last4 = Gitelis | first4 = C. | last5 = Topi | first5 = B. | last6 = Hollander | first6 = G. | last7 = Ghosh | first7 = J. | title = Torsade de Pointes due to Methadone Use in a Patient with HIV and Hepatitis C Coinfection | doi = 10.4061/2010/524764 | journal = Cardiology Research and Practice | volume = 2010 | pages = 1–4 | year = 2010 | pmid = 21253542 | pmc = 3021856 | doi-access = free }}</ref>

A "short-coupled variant of torsade de pointes", which presents without long QT syndrome, was also described in 1994 as having the following characteristics:<ref name="pmid">{{cite journal |vauthors=Leenhardt A, Glaser E, Burguera M, Nürnberg M, Maison-Blanche P, Coumel P | title = Short-coupled variant of torsade de pointes. A new electrocardiographic entity in the spectrum of idiopathic ventricular tachyarrhythmias | journal = Circulation | volume = 89 | issue = 1 | pages = 206–15 |date=January 1994 | pmid = 8281648 | doi = 10.1161/01.CIR.89.1.206 | doi-access = free }}</ref>
* Drastic rotation of the heart's electrical axis
* Prolonged [[QT interval]] ([[LQTS]]) - may not be present in the short-coupled variant of torsade de pointes
* Preceded by long and short RR-intervals - not present in the short-coupled variant of torsade de pointes
* Triggered by a [[premature ventricular contraction]] (R-on-T PVC)

== R-on-T phenomenon ==
The R-on-T phenomenon is the superimposition of a premature ventricular contraction on the T wave of a preceding heartbeat. Studies suggest that the R-on-T phenomenon is likely to start a sustained [[ventricular tachycardia]] and [[ventricular fibrillation]].<ref name=":02">{{Cite journal|last=Engel|first=Toby R.|date=1978-02-01|title=The "R-on-T" Phenomenon: An Update and Critical Review|url=http://annals.org/article.aspx?doi=10.7326/0003-4819-88-2-221|journal=Annals of Internal Medicine|language=en|volume=88|issue=2|pages=221–225|doi=10.7326/0003-4819-88-2-221|issn=0003-4819|pmid=75705|url-access=subscription}}</ref> It's considered a cardiac arrhythmia in which the ventricles of the heart become again excited during the repolarization of the previous heart action. Because part of the heart muscle cannot be excited at this early point in time, a premature chamber action can trigger life-threatening cardiac arrhythmias (e.g., ventricular fibrillation or Torsades de pointes).

On the ECG, this phenomenon is shown when a [[Premature ventricular contraction|ventricular extrasystole]] (R) ([[T wave|T-wave]]) is superimposed during the repolarization phase of the previous action of the heart.<ref name=":02" /> Not all premature chamber actions can trigger these dangerous arrhythmias; the risk is increased with [[Coronary artery disease|ischemia]] of the heart muscle or with prolonged repolarization time ([[long QT syndrome]]).<ref>{{Cite journal|last1=Oksuz|first1=Fatih|last2=Sensoy|first2=Baris|last3=Sahan|first3=Ekrem|last4=Sen|first4=Fatih|last5=Baser|first5=Kazım|last6=Cetin|first6=Hande|last7=Unal|first7=Sefa|last8=Ozeke|first8=Ozcan|last9=Topaloglu|first9=Serkan|last10=Aras|first10=Dursun|date=July 2015|title=The classical "R-on-T" phenomenon|journal=Indian Heart Journal|language=en|volume=67|issue=4|pages=392–394|doi=10.1016/j.ihj.2015.02.030|pmc=4561790|pmid=26304578}}</ref> The arrhythmia can also be triggered when an external stimulus such as [[cardioversion]] falls in the vulnerable phase of the [[cardiac cycle]].

In the Lown grading system of ventricular arrhythmias, the R-on-T phenomenon is the fifth, most threatening class.

== Treatment ==
The treatment of torsades de pointes aims to restore a normal rhythm and to prevent the arrhythmia from recurring. While torsades may spontaneously revert to a normal [[sinus rhythm]], sustained torsades requires emergency treatment to prevent [[cardiac arrest]].<ref name=":0">{{Cite journal|last1=Thomas|first1=Simon H. L.|last2=Behr|first2=Elijah R.|date=March 2016|title=Pharmacological treatment of acquired QT prolongation and torsades de pointes|journal=British Journal of Clinical Pharmacology|volume=81|issue=3|pages=420–427|doi=10.1111/bcp.12726|issn=1365-2125|pmc=4767204|pmid=26183037}}</ref> The most effective treatment to terminate torsades is an [[Cardioversion|electrical cardioversion]] – a procedure in which an electrical current is applied across the heart to temporarily stop and then resynchronise the heart's cells.<ref name=":0" /> Treatment to prevent recurrent torsades includes infusion of [[Magnesium sulfate|magnesium sulphate]],<ref>{{Cite journal|last1=Hoshino|first1=Kenji|last2=Ogawa|first2=Kiyoshi|last3=Hishitani|first3=Takashi|last4=Isobe|first4=Takeshi|last5=Etoh|first5=Yoshikatsu|year=2006|title=Successful uses of magnesium sulfate for torsades de pointes in children with long QT syndrome|journal=Pediatrics International|volume=48|issue=2|pages=112–117|doi=10.1111/j.1442-200X.2006.02177.x|pmid=16635167|s2cid=24904388}}</ref> correction of electrolyte imbalances such as low blood potassium levels ([[Hypokalemia|hypokalaemia]]), and withdrawal of any [[Drug-induced QT prolongation|medications that prolong the QT interval]]. Treatments used to prevent torsades in specific circumstances include [[beta blocker]]s or [[mexiletine]] in long QT syndrome.<ref name=":1">{{Cite journal|last1=Priori|first1=Silvia G.|last2=Blomström-Lundqvist|first2=Carina|last3=Mazzanti|first3=Andrea|last4=Blom|first4=Nico|last5=Borggrefe|first5=Martin|last6=Camm|first6=John|last7=Elliott|first7=Perry Mark|last8=Fitzsimons|first8=Donna|last9=Hatala|first9=Robert|last10=Hindricks|first10=Gerhard|last11=Kirchhof|first11=Paulus|date=November 2015|title=2015 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death: The Task Force for the Management of Patients with Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death of the European Society of Cardiology (ESC)Endorsed by: Association for European Paediatric and Congenital Cardiology (AEPC)|journal=EP Europace |volume=17|issue=11|pages=1601–1687|doi=10.1093/europace/euv319|issn=1532-2092|pmid=26318695|doi-access=free|hdl=11577/3455356|hdl-access=free}}</ref> Occasionally a [[Artificial cardiac pacemaker|pacemaker]] may be used to accelerate the heart's own sinus rhythm, and those at risk of further torsades may be offered an [[Implantable cardioverter-defibrillator|implantable defibrillator]] to automatically detect and defibrillate further episodes of the arrhythmia.<ref name=":1" />

Magnesium is used in the treatment of torsades de pointes because it functions as a physiologic [[calcium channel blocker]]. By blocking the calcium channels in phase 2 of the myocardial action potential, magnesium suppresses the [[Afterdepolarization|early afterdepolarizations]] that occur in this phase with calcium influx into the cell.<ref>{{Cite web |date=2020-10-28 |title=Episode 12: Why does magnesium treat torsades de pointes? |url=https://curiousclinicians.com/2020/10/28/episode-11-why-does-magnesium-treat-torsades-de-pointes/ |access-date=2023-10-23 |website=The Curious Clinicians |language=en}}</ref>

== History ==
The phenomenon was originally described in a French [[medical journal]] by [[Dessertenne]] in 1966, when he observed this cardiac rhythm disorder in an 80-year-old female patient with complete intermittent [[atrioventricular block]]. In coining the term, he referred his colleagues to the "Dictionnaire Le Robert", a bilingual French English dictionary, of which his wife had just given him a copy. Here, "torsade" is defined as: {{citation needed|date=February 2021}}
* a bundle of threads, twisted in a helix or spiral, for ornamental purposes (such as in an [[Aran sweater]]);
* long hair twisted together;
* an ornamental motif, as seen on architectural columns.

==Terminology==
The singular and plural forms (''torsade de pointes'', ''torsades de pointes'') have often been used. The question of whether each one is grammatically "correct" and the others "incorrect" has repeatedly arisen. This is seen among major medical dictionaries, where one enters only the plural form, another enters the plural form as the [[headword]] but lists the singular as a variant, and yet another enters the singular form as the headword and gives a usage comment saying that the plural is not preferred. One group of physicians has suggested that it would make the most sense to use the singular form to refer to the arrhythmia entity (where an arrhythmia may involve one or multiple episodes), and that one might best reserve the plural form for describing repeated twisting during a single episode.<ref name="Circulation_1999_100_1462">{{cite journal|author=Moise NS |title=As Americans, we should get this right [correspondence and response] |journal=Circulation |year=1999 |volume=100 |issue=13 |page=1462 |doi=10.1161/01.CIR.100.13.1462 |pmid=10500317 |doi-access=free }}</ref> Other authors have suggested all three words should be plural.<ref name="mullins">{{cite journal|author= Mullins ME |title=Mon bête noir (my pet peeve) |journal=Journal of Medical Toxicology |year=2011 |volume=7 |issue=2 |page=181 |doi=10.1007/s13181-011-0153-7 |pmid=21461788 |pmc=3724434 |doi-access=free }}</ref> Regarding the [[natural language]] variation, they concluded, in good nature, "Wasn't it the French who coined the term ''vive la difference''?"<ref name="Circulation_1999_100_1462" />

== References ==
{{reflist}}

{{Medical resources
| DiseasesDB = 29252
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| eMedicineSubj = med
| eMedicineTopic = 2286
| eMedicine_mult = {{eMedicine2|emerg|596}}
| MeshID = D016171
}}
{{Heart diseases}}

[[Category:Cardiac arrhythmia]]
[[Category:French medical phrases]]

Amaurosis fugax

2025-06-19T18:24:47Z

2601:642:C301:2730:B1AA:9310:CFA0:A058: ce

{{Infobox medical condition
| name = Amaurosis fugax
| synonyms =
| image = Gray873.png
| caption = The arteries of the choroid and iris. The greater part of the sclera has been removed.
| pronounce =
| field =
| symptoms =Temporary fleeting of vision in one or both eyes
| complications =[[Stroke]]<ref name="benavente" /><ref name="rothwell" />
| onset =
| duration =Seconds to hours
| types =
| causes =
| risks =
| diagnosis =
| differential =
| prevention =
| treatment =
| medication =
| prognosis =
| frequency =
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'''Amaurosis fugax''' ({{langx|grc|[[wikt:ἀμαύρωσις#Ancient Greek|ἀμαύρωσις]]}}, {{lang|grc-Latn|amaurosis}} meaning 'darkening', 'dark', or 'obscure', {{langx|la|[[wikt:fugax#Latin|fugax]]}} meaning 'fleeting') is a painless temporary [[monocular vision|loss of vision in one]] or [[binocular vision|both eyes]].<ref name="fisher">{{cite journal | vauthors = Fisher CM | title = 'Transient monocular blindness' versus 'amaurosis fugax' | journal = Neurology | volume = 39 | issue = 12 | pages = 1622–4 | date = December 1989 | pmid = 2685658 | doi = 10.1212/wnl.39.12.1622 |s2cid=13315378 }}</ref>

==Signs and symptoms==
The experience of amaurosis fugax is classically described as a temporary loss of vision in one or both eyes that appears as a "black [[curtain]] coming down vertically into the [[visual field|field of vision]] in one eye;" however, this altitudinal visual loss is not the most common form. In one study, only 23.8 percent of patients with transient monocular vision loss experienced the classic "curtain" or "shade" descending over their vision.<ref name="pmid1852179">{{cite journal | vauthors = ((North American Symptomatic Carotid Endarterectomy Trial Collaborators)), Barnett HJ, Taylor DW, Haynes RB, Sackett DL, Peerless SJ, Ferguson GG, Fox AJ, Rankin RN, Hachinski VC, Wiebers DO, Eliasziw M | title = Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis | journal = N Engl J Med | volume = 325 | issue = 7 | pages = 445–53 | date = August 1991 | pmid = 1852179 | doi = 10.1056/NEJM199108153250701 | doi-access = free }}</ref> Other descriptions of this experience include a monocular blindness, dimming, fogging, or blurring.<ref name="Lord">{{cite journal | vauthors = Lord RS | title = Transient monocular blindness | journal = Aust N Z J Ophthalmol | volume = 18 | issue = 3 | pages = 299–305 | date = August 1990 | pmid = 2261177 | doi = 10.1111/j.1442-9071.1990.tb00624.x | doi-access = free }}</ref> Total or sectorial [[vision loss]] typically lasts only a few seconds, but may last minutes or even hours. Duration depends on the cause of the vision loss. Obscured vision due to papilledema may last only seconds, while a severely atherosclerotic carotid artery may be associated with a duration of one to ten minutes.<ref name="Donders">{{cite journal | vauthors = Donders RC, ((Dutch Tmb Study Group))| title = Clinical features of transient monocular blindness and the likelihood of atherosclerotic lesions of the internal carotid artery | journal = J Neurol Neurosurg Psychiatry | volume = 71 | issue = 2 | pages = 247–9 | date = August 2001 | pmid = 11459904 | pmc = 1737502 | doi = 10.1136/jnnp.71.2.247 }}</ref> Certainly, additional symptoms may be present with the amaurosis fugax, and those findings will depend on the cause of the transient monocular vision loss.{{citation needed|date=December 2020}}

==Cause==
Prior to 1990, amaurosis fugax could, "clinically, be divided into four identifiable symptom complexes, each with its underlying pathoetiology: embolic, hypoperfusion, angiospasm, and unknown".<ref name="Burde">{{cite journal | vauthors = Burde RM | title = Amaurosis fugax. An overview | journal = J Clin Neuroophthalmol | volume = 9 | issue = 3 | pages = 185–9 | date = September 1989 | pmid = 2529279 }}</ref> In 1990, the causes of amaurosis fugax were better refined by the Amaurosis Fugax Study Group, which has defined five distinct classes of transient monocular blindness based on their supposed cause: '''embolic, hemodynamic, ocular, neurologic''', and '''idiopathic''' (or "no cause identified").<ref name="ASG">{{cite journal | vauthors = ((The Amaurosis Fugax Study Group))| title = Current management of amaurosis fugax. The Amaurosis Fugax Study Group | journal = Stroke | volume = 21 | issue = 2 | pages = 201–8 | date = February 1990 | pmid = 2406992 | doi = 10.1161/01.str.21.2.201 | doi-access=free }}</ref> Concerning the pathology underlying these causes (except [[idiopathic]]), "some of the more frequent causes include atheromatous disease of the internal carotid or ophthalmic artery, vasospasm, optic neuropathies, giant cell arteritis, angle-closure glaucoma, increased intracranial pressure, orbital compressive disease, a [[Coronary steal|steal phenomenon]], and blood hyperviscosity or hypercoagulability."<ref name="Newman">{{cite book |vauthors = Newman NJ |chapter=Cerebrovascular disease |veditors = Hoyt WG, Miller N, Walsh F, Newman NJ|title=Walsh and Hoyt's Clinical Neuro-Ophthalmology |publisher=Williams & Wilkins |location=Baltimore |year=1998 |pages=3420–6 |isbn=0-683-30232-9 |volume=3 |edition=5th}}</ref>

===Embolic and hemodynamic origin===
With respect to embolic and hemodynamic causes, this transient monocular visual loss ultimately occurs due to a temporary reduction in [[retinal artery]], [[ophthalmic artery]], or [[Ciliary arteries|ciliary artery]] blood flow, leading to a decrease in retinal circulation which, in turn, causes retinal hypoxia.<ref name="vasospastic">{{cite journal |vauthors=Jehn A, Frank Dettwiler B, Fleischhauer J, Sturzenegger M, Mojon DS |title=Exercise-induced vasospastic amaurosis fugax |journal=Arch. Ophthalmol. |volume=120 |issue=2 |pages=220–2 |date=February 2002 |pmid=11831932 |url= https://jamanetwork.com/journals/jamaophthalmology/fullarticle/269443 |access-date=2007-03-26 |archive-url=https://web.archive.org/web/20070929133329/http://archopht.ama-assn.org/cgi/content/extract/120/2/220 |archive-date=2007-09-29 |url-status=live }}</ref> While, most commonly, emboli causing amaurosis fugax are described as coming from an atherosclerotic [[carotid artery]], any emboli arising from vasculature preceding the [[retinal artery]], [[ophthalmic artery]], or [[ciliary arteries]] may cause this transient monocular blindness.{{citation needed|date=December 2021}}
* Atherosclerotic [[carotid artery]]: Amaurosis fugax may present as a type of [[transient ischemic attack]] (TIA), during which an [[Embolism|embolus]] unilaterally obstructs the lumen of the [[retinal artery]] or [[ophthalmic artery]], causing a decrease in blood flow to the ipsilateral retina. The most common source of these athero-emboli is an atherosclerotic carotid artery.<ref name="braat">{{cite journal |vauthors=Braat A, Hoogland PH, DeVries AC, de Mol VanOtterloo JC |title=Amaurosis Fugax and Stenosis of the Ophthalmic Artery |journal=Vasc Endovascular Surg |volume=35 |issue=2 |pages=141–2 |year=2001 |doi=10.1177/153857440103500210 |pmid=11668383 |s2cid=38943888 }}</ref> However, a severely atherosclerotic [[carotid artery]] may also cause amaurosis fugax due to its [[stenosis]] of blood flow, leading to ischemia when the retina is exposed to bright light.<ref name="Kaiboriboon">{{cite journal |vauthors= Kaiboriboon K, Piriyawat P, Selhorst JB |title=Light-induced amaurosis fugax |journal=Am. J. Ophthalmol. |volume=131 |issue=5 |pages=674–6 |date=May 2001 |pmid=11336956 |doi=10.1016/S0002-9394(00)00874-6}}</ref> "Unilateral visual loss in bright light may indicate ipsilateral carotid artery occlusive disease and may reflect the inability of borderline circulation to sustain the increased retinal metabolic activity associated with exposure to bright light."<ref name="Furlan">{{cite journal |vauthors=Furlan AJ, Whisnant JP, Kearns TP |title=Unilateral visual loss in bright light. An unusual symptom of carotid artery occlusive disease |journal=Arch. Neurol. |volume=36 |issue=11 |pages=675–6 |date= November 1979 |pmid=508123 |doi=10.1001/archneur.1979.00500470045007 }}</ref>
* Atherosclerotic [[ophthalmic artery]]: Will present similarly to an atherosclerotic internal carotid artery.{{citation needed|date=December 2021}}
* Cardiac [[emboli]]: Thrombotic emboli arising from the heart may also cause luminal obstruction of the retinal, ophthalmic, and/or ciliary arteries, causing decreased blood flow to the ipsilateral retina; examples being those arising due to (1) atrial fibrillation, (2) valvular abnormalities including post-rheumatic valvular disease, mitral valve prolapse, and a bicuspid aortic valve, and (3) [[atrial myxoma]]s.{{citation needed|date=December 2021}}
* Temporary [[vasospasm]] leading to decreased blood flow can be a cause of amaurosis fugax.<ref name="Fisher">{{cite journal |vauthors =Fisher M |title=Transient monocular blindness associated with hemiplegia |journal=Arch. Ophthalmol. |volume=47 |issue=2 |pages=167–203 |year=1952 | pmid = 14894017 |doi=10.1001/archopht.1952.01700030174005}}</ref><ref name="Ellenberger">{{cite journal |vauthors=Ellenberger C, Epstein AD |title=Ocular complications of atherosclerosis: what do they mean? |journal=Semin Neurol |volume=6 |issue=2 |pages=185–93 |date=June 1986 |pmid=3332423 |doi=10.1055/s-2008-1041462 }}</ref> Generally, these episodes are brief, lasting no longer than five minutes,<ref name="stephen">{{cite journal |doi=10.1056/NEJM199109193251207 |vauthors=Burger SK, Saul RF, Selhorst JB, Thurston SE |title=Transient monocular blindness caused by vasospasm |journal=N. Engl. J. Med. |volume=325 |issue=12 |pages=870–3 |date=September 1991 |pmid=1875972 |doi-access=free }}</ref> and have been associated with exercise.<ref name="vasospastic" /><ref name="Imes">{{cite journal |vauthors=Imes RK, Hoyt WF |title=Exercise-induced transient visual events in young healthy adults |journal=J Clin Neuroophthalmol |volume=9 |pages=178–80 |year=1989 |pmid=2529277 |issue=3 }}</ref> These vasospastic episodes are not restricted to young and healthy individuals. "Observations suggest that a systemic hemodynamic challenge provoke[s] the release of vasospastic substance in the retinal vasculature of one eye."<ref name="stephen" />
* [[Giant cell arteritis]]: Giant cell arteritis can result in granulomatous inflammation within the central retinal artery and posterior ciliary arteries of the eye, resulting in partial or complete occlusion, leading to decreased blood flow manifesting as amaurosis fugax. Commonly, amaurosis fugax caused by giant cell arteritis may be associated with jaw claudication and headache. However, it is also not uncommon for these patients to have no other symptoms.<ref name="Hayreh2">{{cite journal |vauthors=Hayreh SS, Podhajsky PA, Zimmerman B |title=Occult giant cell arteritis: ocular manifestations |journal=Am. J. Ophthalmol. |volume=125 |issue=4 |pages=521–6 |date=April 1998 |pmid=9559738 |doi=10.1016/S0002-9394(99)80193-7 }}</ref> One comprehensive review found a two to nineteen percent incidence of amaurosis fugax among these patients.<ref name="goodman">{{cite journal |vauthors =Goodman BW |title=Temporal arteritis |journal=Am. J. Med. |volume=67 |issue=5 |pages=839–52 |date=November 1979 |pmid=389046 |doi=10.1016/0002-9343(79)90744-7 }}</ref>
* [[Systemic lupus erythematosus]]<ref name="giorgi">{{cite journal |vauthors=Giorgi D, David V, Afeltra A, Gabrieli CB |title=Transient visual symptoms in systemic lupus erythematosus and antiphospholipid syndrome |journal=Ocul. Immunol. Inflamm. |volume=9 |issue=1 |pages=49–57 |date=March 2001 |pmid=11262668 |doi=10.1076/ocii.9.1.49.3980 |s2cid=35161683 }}</ref><ref name="GoldD">{{cite journal |vauthors=Gold D, Feiner L, Henkind P |title=Retinal arterial occlusive disease in systemic lupus erythematosus |journal=Arch. Ophthalmol. |volume=95 |issue=9 |pages=1580–5 |date=September 1977 |pmid=901267 |doi=10.1001/archopht.1977.04450090102008 }}</ref>
* [[Periarteritis nodosa]]<ref name="NewmanNM">{{cite journal |vauthors=Newman NM, Hoyt WF, Spencer WH |title=Macula-sparing monocular blackouts. Clinical and pathologic investigations of intermittent choroidal vascular insufficiency in a case of periarteritis nodosa |journal=Arch. Ophthalmol. |volume=91 |issue=5 |pages=367–70 |date=May 1974 |pmid=4150748 |doi=10.1001/archopht.1974.03900060379006 }}</ref>
* [[Eosinophilia|Eosinophilic]] [[vasculitis]]<ref name="Schwartz">{{cite journal |vauthors=Schwartz ND, So YT, Hollander H, Allen S, Fye KH |title=Eosinophilic vasculitis leading to amaurosis fugax in a patient with acquired immunodeficiency syndrome |journal=Arch. Intern. Med. |volume=146 |pages=2059–60 |year=1986 |doi=10.1001/archinte.146.10.2059 |pmid=3767551 |issue=10 }}</ref>
* [[Hyperviscosity syndrome]]<ref name="Bacigalupi" />
** [[Polycythemia]]<ref name="Berdel">{{cite journal |vauthors=Berdel WE, Theiss W, Fink U, Rastetter J |title=Peripheral arterial occlusion and amaurosis fugax as the first manifestation of polycythemia vera. A case report |journal=Blut |volume=48 |issue=3 |pages=177–80 |date=March 1984 |pmid=6697006 |doi=10.1007/BF00320341 |s2cid=13588599 }}</ref>
* [[Hypercoagulability]]<ref name="Mundall">{{cite journal |vauthors=Mundall J, Quintero P, Von Kaulla KN, Harmon R, Austin J |title=Transient monocular blindness and increased platelet aggregability treated with aspirin. A case report |journal=Neurology |volume=22 |issue=3 |pages=280–5 |date=March 1972 |pmid=5062262 |doi=10.1212/wnl.22.3.280|s2cid=552116 }}</ref>
** [[Protein C deficiency]]<ref name="smith_db">{{cite journal |vauthors=Smith DB, Ens GE |title=Protein C deficiency: a cause of amaurosis fugax? |journal=J. Neurol. Neurosurg. Psychiatry |volume=50 |issue=3 |pages=361–2 |date=March 1987 |pmid=3559620 |pmc=1031809 |doi=10.1136/jnnp.50.3.361}}</ref>
** [[Antiphospholipid antibodies]]<ref name="Digre">{{cite journal |vauthors=Digre KB, Durcan FJ, Branch DW, Jacobson DM, Varner MW, Baringer JR |title=Amaurosis fugax associated with antiphospholipid antibodies |journal=Annals of Neurology |volume=25 |issue=3 |pages=228–32 |date=March 1989 |pmid=2729913 |doi=10.1002/ana.410250304 |s2cid=28110036 }}</ref>
*** [[Anticardiolipin antibodies]]<ref name="DigreK" />
*** [[Lupus anticoagulant]]<ref name="Landi">{{cite journal |vauthors=Landi G, Calloni MV, Grazia Sabbadini M, Mannuccio Mannucci P, Candelise L |title=Recurrent ischemic attacks in two young adults with lupus anticoagulant |journal=Stroke |volume=14 |issue=3 |pages=377–9 |year=1983 |pmid=6419415 |doi=10.1161/01.STR.14.3.377 |doi-access=free }}</ref><ref name="Elias">{{cite journal |vauthors=Elias M, Eldor A |title=Thromboembolism in patients with the 'lupus'-type circulating anticoagulant |journal=Arch. Intern. Med. |volume=144 |issue=3 |pages=510–5 |date=March 1984 |pmid=6367679 |doi=10.1001/archinte.144.3.510 }}</ref>
* [[Thrombocytosis]]<ref name="DigreK" />
* [[Subclavian steal syndrome]]
* [[Malignant hypertension]] can cause ischemia of the optic nerve head, leading to transient monocular visual loss.<ref name="HayrehSS">{{cite journal |vauthors=Hayreh SS, Servais GE, Virdi PS |title=Fundus lesions in malignant hypertension. V. Hypertensive optic neuropathy |journal=Ophthalmology |volume=93 |issue=1 |pages=74–87 |date=January 1986 |pmid=3951818 |doi=10.1016/s0161-6420(86)33773-4}}</ref>
* Substance use-related intravascular emboli<ref name="ASG" />
* [[Iatrogenic]]: Amaurosis fugax can present as a complication following [[carotid endarterectomy]], carotid [[angiography]], [[cardiac catheterization]], and [[cardiac bypass]].<ref name="DigreK" />

===Ocular origin===
Ocular causes include:
* [[Iritis]]<ref name="Sorensen">{{cite journal |doi=10.1111/j.1755-3768.1983.tb04348.x |vauthors =Sørensen PN |title=Amaurosis fugax. A unselected material |journal=Acta Ophthalmol (Copenh) |volume=61 |issue=4 |pages=583–8 |date=August 1983 |pmid=6637419 |s2cid =221395995 }}</ref>
* [[Keratitis]]<ref name="Bacigalupi">{{cite journal |vauthors = Bacigalupi M |title=Amaurosis Fugax-A Clinical Review |journal=The Internet Journal of Allied Health Sciences and Practice |volume=4 |issue=2 |pages=1–6 |date=April 2006 |url=http://ijahsp.nova.edu/articles/vol4num2/Bacigalupi.pdf}}</ref>
* [[Blepharitis]]<ref name="Bacigalupi" />
* [[Optic disc drusen]]<ref name="DigreK" />
* [[Posterior vitreous detachment]]<ref name="Bacigalupi" />
* [[glaucoma|Closed-angle glaucoma]]<ref name="Ravits">{{cite journal |vauthors=Ravits J, Seybold ME |title=Transient monocular visual loss from narrow-angle glaucoma |journal=Arch. Neurol. |volume=41 |issue=9 |pages=991–3 |date=September 1984 |pmid=6477235 |doi=10.1001/archneur.1984.04050200097026 }}</ref>
* Transient elevation of intraocular pressure<ref name="ASG" /><ref name="Sorensen" />
* Intraocular [[hemorrhage]]<ref name="ASG" />
* [[Coloboma]]<ref name="DigreK" />
* [[Myopia]]<ref name="DigreK" />
* Orbital [[hemangioma]]<ref name="BrownGC">{{cite journal |vauthors=Brown GC, Shields JA |title=Amaurosis fugax secondary to presumed cavernous hemangioma of the orbit |journal=Ann Ophthalmol |volume=13 |issue=10 |pages=1205–9 |date=October 1981 |pmid=7316347 }}</ref>
* Orbital [[osteoma]]<ref name="WilkesSR">{{cite journal |vauthors=Wilkes SR, Trautmann JC, DeSanto LW, Campbell RJ |title=Osteoma: an unusual cause of amaurosis fugax |journal=Mayo Clin. Proc. |volume=54 |issue=4 |pages=258–60 |date=April 1979 |pmid=423606 }}</ref>
* [[Keratoconjunctivitis sicca]]<ref name="DigreK" /> testing

===Neurologic origin===
Neurological causes include:
* [[Optic neuritis]]<ref name="ASG" />
* Compressive [[optic neuropathy|optic neuropathies]]<ref name="ASG" /><ref name="DigreK">{{cite book |vauthors=Corbett JW, Digre KB |title=Practical viewing of the optic disc |publisher=Butterworth-Heinemann |location=Oxford |year=2003 |pages=269–344 |isbn=0-7506-7289-7 |chapter=Amaurosis Fugax and Not So Fugax—Vascular Disorders of the Eye |chapter-url=http://intl.elsevierhealth.com/e-books/pdf/783.pdf |access-date=2007-03-29 |archive-date=2007-09-26 |archive-url=https://web.archive.org/web/20070926225959/http://intl.elsevierhealth.com/e-books/pdf/783.pdf |url-status=dead }}</ref>
* [[Papilledema]]: "The underlying mechanism for visual obscurations in all of these patients appears to be transient ischemia of the optic nerve head consequent to increased tissue pressure. Axonal swelling, intraneural masses, and increased influx of [[interstitial fluid]] may all contribute to increases in tissue pressure in the optic nerve head. The consequent reduction in perfusion pressure renders the small, low-pressure vessels that supply the optic nerve head vulnerable to compromise. Brief fluctuations in intracranial or systemic blood pressure may then result in transient loss of function in the eyes."<ref name="Sadun">{{cite journal |vauthors=Sadun AA, Currie JN, Lessell S |title=Transient visual obscurations with elevated optic discs |journal=Annals of Neurology |volume=16 |issue=4 |pages=489–94 |date=October 1984 |pmid=6497356 |doi=10.1002/ana.410160410 |s2cid=2245543 }}</ref> Generally, this transient visual loss is also associated with a headache and optic disk swelling.
* [[Multiple sclerosis]] can cause amaurosis fugax due to a unilateral conduction block, which is a result of demyelination and inflammation of the optic nerve, and "...possibly by defects in synaptic transmission and putative circulating blocking factors."<ref name="Smith">{{cite journal |vauthors=Smith KJ, McDonald WI |author2-link=W. Ian McDonald |title=The pathophysiology of multiple sclerosis: the mechanisms underlying the production of symptoms and the natural history of the disease |journal=Philosophical Transactions of the Royal Society B |volume=354 |issue=1390 |pages=1649–73 |date=October 1999 |pmid=10603618 |pmc=1692682 |doi=10.1098/rstb.1999.0510 }}</ref>
* [[Migraine]]<ref name="mattsson">{{cite journal | vauthors = Mattsson P, Lundberg PO | title = Characteristics and prevalence of transient visual disturbances indicative of migraine visual aura | journal = Cephalalgia | volume = 19 | issue = 5 | pages = 479–84 | date = June 1999 | pmid = 10403062 | doi = 10.1046/j.1468-2982.1999.019005479.x | s2cid=5961275 | doi-access = free }}{{cite journal |vauthors=Cologno D, Torelli P, Manzoni GC |title=Transient visual disturbances during migraine without aura attacks |journal=Headache |volume=42 |issue=9 |pages=930–3 |date=October 2002 |pmid=12390623 |doi=10.1046/j.1526-4610.2002.02216.x|s2cid=32304894 }}{{cite journal |vauthors = Connor RC |title=Complicated migraine. A study of permanent neurological and visual defects caused by migraine |journal=Lancet |volume=2 |issue=7265 |pages=1072–5 |date=November 1962 |pmid=14022628 |doi=10.1016/s0140-6736(62)90782-1}}{{cite journal |vauthors =Carroll D |title=Retinal migraine |journal=Headache |volume=10 |issue=1 |pages=9–13 |date=April 1970 |pmid=5444866 |doi=10.1111/j.1526-4610.1970.hed1001009.x |s2cid=46246035 }}{{cite journal |vauthors=McDonald WI, Sanders MD |title=Migraine complicated by ischaemic papillopathy |journal=Lancet |volume=2 |issue=7723 |pages=521–3 |date=September 1971 |pmid=4105666 |doi=10.1016/s0140-6736(71)90440-5}}{{cite journal |vauthors=Wolter JR, Burchfield WJ |title=Ocular migraine in a young man resulting in unilateral transient blindness and retinal edema |journal=Pediatr Ophthalmol. |volume=8 |pages=173–6 |year=1971 }}{{cite journal |vauthors=Kline LB, Kelly CL |title=Ocular migraine in a patient with cluster headaches |journal=Headache |volume=20 |issue=5 |pages=253–7 |date=September 1980 |pmid=7451120 |doi=10.1111/j.1526-4610.1980.hed2005253.x |s2cid=29684052 }}{{cite journal |author =Corbett JJ. |title=Neuro-ophthalmologic complications of migraine and cluster headaches |journal=Neurol. Clin. |volume=1 |issue=4 |pages=973–95 |year=1983 | pmid = 6390159 |doi=10.1016/S0733-8619(18)31134-4 }}</ref>
* [[Idiopathic Intracranial Hypertension]]<ref name="HedgesT" />
* [[Intracranial tumor]]<ref name="HedgesT">{{cite journal |author=Hedges TR |title=The terminology of transient visual loss due to vascular insufficiency |journal=Stroke |volume=15 |issue=5 |pages=907–8 |year=1984 |pmid=6474546 |doi=10.1161/01.STR.15.5.907 |s2cid=8664120 |doi-access=free }}</ref>
* [[Conversion disorder|Psychogenic]]<ref name="Bacigalupi" />

==Diagnosis==
Despite the temporary nature of the vision loss, those experiencing amaurosis fugax are usually advised to consult a [[physician]] immediately as it is a [[symptom]] that may herald serious vascular events, including [[transient ischemic attack]] (TIA) or [[stroke]].<ref name="benavente">{{cite journal |vauthors=Benavente O, Eliasziw M, Streifler JY, Fox AJ, Barnett HJ, Meldrum H |title=Prognosis after transient monocular blindness associated with carotid-artery stenosis |journal=N. Engl. J. Med. |volume=345 |issue=15 |pages=1084–90 |date=October 2001 |pmid=11596587 |doi=10.1056/NEJMoa002994|doi-access=free }}</ref><ref name="rothwell">{{cite journal |vauthors=Rothwell PM, Warlow CP |title=Timing of TIAs preceding stroke: time window for prevention is very short |journal=Neurology |volume=64 |issue=5 |pages=817–20 |date=March 2005 |pmid=15753415 |doi=10.1212/01.WNL.0000152985.32732.EE |s2cid=19550244 }}</ref> Restated, "because of the brief interval between the transient event and a stroke or blindness from temporal arteritis, the workup for transient monocular blindness should be undertaken without delay." If the patient has no history of giant cell arteritis, the probability of vision preservation is high; however, the chance of a stroke reaches that of a hemispheric TIA. Therefore, investigation of cardiac disease is justified.<ref name="ASG" />

A diagnostic evaluation should begin with the patient's history, followed by a physical exam, with particular importance being paid to the ophthalmic examination with regard to signs of ocular ischemia. When investigating amaurosis fugax, an ophthalmologic consultation is absolutely warranted if available. Several concomitant laboratory tests should also be ordered to investigate some of the more common, systemic causes listed above, including a complete blood count, erythrocyte sedimentation rate, lipid panel, and blood glucose level. If a particular cause is suspected based on the history and physical, additional relevant labs should be ordered.<ref name="ASG" />

If laboratory tests are abnormal, a systemic disease process is likely, and if the ophthalmologic examination is abnormal, ocular disease is likely. However, in the event that both of these routes of investigation yield normal findings or an inadequate explanation, non-invasive duplex ultrasound studies are recommended to identify carotid artery disease. Most episodes of amaurosis fugax are the result of stenosis of the ipsilateral carotid artery.<ref name="smit">{{cite journal |vauthors=Smit RL, Baarsma GS, Koudstaal PJ |title=The source of embolism in amaurosis fugax and retinal artery occlusion |journal=Int Ophthalmol |volume=18 |issue=2 |pages=83–6 |year=1994 |pmid=7814205 |url=http://www.iovs.org/cgi/reprint/1/1/136.pdf |doi=10.1007/BF00919244|s2cid=394747 }}</ref> With that being the case, researchers investigated how best to evaluate these episodes of vision loss, and concluded that for patients ranging from 36 to 74 years old, "...carotid artery duplex scanning should be performed...as this investigation is more likely to provide useful information than an extensive cardiac screening (ECG, Holter 24-hour monitoring, and precordial echocardiography)."<ref name="smit"/> Additionally, concomitant head CT or MRI imaging is also recommended to investigate the presence of a "clinically silent cerebral embolism."<ref name="ASG" />

If the results of the ultrasound and intracranial imaging are normal, "renewed diagnostic efforts may be made," during which [[fluorescein angiography]] is an appropriate consideration. However, carotid angiography may not be necessary in the presence of a normal ultrasound and CT.<ref name="walsh">{{cite journal |vauthors=Walsh J, Markowitz I, Kerstein MD |title=Carotid endarterectomy for amaurosis fugax without angiography |journal=Am. J. Surg. |volume=152 |issue=2 |pages=172–4 |date=August 1986 |pmid=3526933 |doi=10.1016/0002-9610(86)90236-9}}</ref>

==Treatment==
Fleeting loss of vision does not in itself require any treatment, but it may indicate an underlying condition, sometimes serious, that must be treated. If the diagnostic workup reveals a systemic disease process, directed therapies to treat the underlying cause are required. If the amaurosis fugax is caused by an atherosclerotic lesion, use of [[aspirin]] as an [[anticoagulant]] is indicated, and a [[carotid endarterectomy]] is considered based on the location and grade of the stenosis. Generally, if the carotid artery is still patent, the greater the stenosis, the greater the indication for endarterectomy. "Amaurosis fugax appears to be a particularly favorable indication for carotid endarterectomy. Left untreated, this event carries a high risk of stroke; after carotid endarterectomy, which has a low operative risk, there is a very low postoperative stroke rate."<ref name="bernstein">{{cite journal |vauthors=Bernstein EF, Dilley RB |title=Late results after carotid endarterectomy for amaurosis fugax |journal=J. Vasc. Surg. |volume=6 |issue=4 |pages=333–40 |date=October 1987 |pmid=3656582 |doi=10.1016/0741-5214(87)90003-6 |doi-access=free }}</ref> However, the rate of subsequent stroke after amaurosis is significantly less than after a hemispheric TIA, therefore there remains debate as to the precise indications for which a carotid endarterectomy should be performed. If the full diagnostic workup is completely normal, patient observation is recommended.<ref name="ASG" />

==See also==
* [[Amaurosis]]
* [[Hemianopsia]]
* [[Ocular ischemic syndrome]]
* [[Retinal migraine]]

==References==
{{Reflist}}

== External links ==
{{Medical resources
| DiseasesDB = 501
| ICD10 = {{ICD10|G|45|3|g|40}}
| ICD9 = {{ICD9|362.34}}
| ICDO =
| OMIM =
| MedlinePlus = 000784
| eMedicineSubj = neuro
| eMedicineTopic = 480
| MeshID = D020757
}}
{{Eye pathology}}
{{Cerebrovascular diseases|state=expanded}}

[[Category:Stroke]]
[[Category:Eye diseases]]
[[Category:Episodic and paroxysmal disorders]]
[[Category:Symptoms]]

Obesity hypoventilation syndrome

2025-06-19T15:07:48Z

2601:642:C301:2730:B1AA:9310:CFA0:A058: ce

{{Short description|Condition in which severely overweight people fail to breathe rapidly or deeply enough}}
{{Infobox medical condition (new)
| name = Obesity hypoventilation syndrome
| synonyms = Pickwickian syndrome
| image = Cpap-example.jpg
| caption = Obesity hypoventilation syndrome often improves with positive airway pressure treatment administered overnight by a machine such as this device.
| pronounce =
| field = [[Respirology]]
| symptoms =
| complications =
| onset =
| duration =
| types =
| causes =
| risks = [[Obesity]]
| diagnosis =
| differential =
| prevention =
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| prognosis =
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}}

'''Obesity hypoventilation syndrome''' ('''OHS''') is a condition in which [[obesity|severely overweight]] people [[hypoventilation|fail to breathe rapidly or deeply enough]], resulting in low [[oxygen]] levels and high blood [[carbon dioxide]] (CO2) levels. The syndrome is often associated with [[obstructive sleep apnea]] (OSA), which causes periods of absent or reduced breathing in sleep, resulting in many partial awakenings during the night and sleepiness during the day.<ref>Casey KR, Cantillo KO, Brown LK. Sleep-related hypoventilation/hypoxemic syndromes. Chest. 2007;131(6):1936-48.</ref> The disease puts strain on the heart, which may lead to [[heart failure]] and [[edema|leg swelling]].


Obesity hypoventilation syndrome is defined as the combination of [[obesity]] and an [[hypercapnia|increased blood carbon dioxide]] level during the day that is not attributable to another cause of [[hypoventilation|excessively slow or shallow breathing]].<ref>American Academy of Sleep Medicine. International Classification
of Sleep Disorders. 3rd ed. Darien, IL: American Academy of Sleep Medicine; 2014.</ref>


The most effective treatment is [[Weight loss#Intentional|weight loss]], but this may require [[bariatric surgery]] to achieve.<ref name=ATS2019>{{cite journal |last1=Mokhlesi |first1=B |last2=Masa |first2=JF |last3=Brozek |first3=JL |last4=Gurubhagavatula |first4=I |last5=Murphy |first5=PB |last6=Piper |first6=AJ |last7=Tulaimat |first7=A |last8=Afshar |first8=M |last9=Balachandran |first9=JS |last10=Dweik |first10=RA |last11=Grunstein |first11=RR |last12=Hart |first12=N |last13=Kaw |first13=R |last14=Lorenzi-Filho |first14=G |last15=Pamidi |first15=S |last16=Patel |first16=BK |last17=Patil |first17=SP |last18=Pépin |first18=JL |last19=Soghier |first19=I |last20=Tamae Kakazu |first20=M |last21=Teodorescu |first21=M |title=Evaluation and Management of Obesity Hypoventilation Syndrome. An Official American Thoracic Society Clinical Practice Guideline. |journal=American Journal of Respiratory and Critical Care Medicine |date=1 August 2019 |volume=200 |issue=3 |pages=e6–e24 |doi=10.1164/rccm.201905-1071ST |pmid=31368798|pmc=6680300 }}</ref> Weight loss of 25 to 30% is usually required to resolve the disorder.<ref name=ATS2019/> The other first-line treatment is non-invasive positive airway pressure (PAP), usually in the form of [[continuous positive airway pressure]] (CPAP) at night.<ref name=Olson2005>{{cite journal |vauthors=Olson AL, Zwillich C |title=The obesity hypoventilation syndrome |journal=Am. J. Med. |volume=118 |issue=9 |pages=948–56 |year=2005 |pmid=16164877 |doi=10.1016/j.amjmed.2005.03.042|s2cid=37801868 |doi-access=free }}</ref><ref name=Mokhlesi>{{cite journal |vauthors=Mokhlesi B, Tulaimat A |title=Recent advances in obesity hypoventilation syndrome |journal=Chest |volume=132 |issue=4 |pages=1322–36 |date=October 2007 |pmid=17934118 |doi=10.1378/chest.07-0027 |url=http://www.chestjournal.org/cgi/content/full/132/4/1322 |access-date=2008-11-22 |archive-date=2008-12-08 |archive-url=https://web.archive.org/web/20081208144434/http://www.chestjournal.org/cgi/content/full/132/4/1322 |url-status=dead |url-access=subscription }}</ref> The disease was known initially in the 1950s, as "Pickwickian syndrome" in reference to a [[Charles Dickens|Dickensian]] character.<ref name=Mokhlesi/>

==Signs and symptoms==
Most people with obesity hypoventilation syndrome have concurrent [[sleep apnea|obstructive sleep apnea]], a condition characterized by [[snoring]], brief episodes of [[apnea]] (cessation of breathing) during the night, interrupted sleep, and [[excessive daytime sleepiness]]. In OHS, sleepiness may be worsened by elevated blood levels of [[carbon dioxide]], which causes drowsiness ("CO2 narcosis"). Other symptoms present in both conditions are [[clinical depression|depression]], and [[hypertension]] (high blood pressure), which is difficult to [[antihypertensive|control with medication]].<ref name=Olson2005/> The high carbon dioxide can also cause [[headache]]s, which tend to worsen in the morning.<ref name="McNicholas">{{cite book | last=McNicholas | first=WT | author2=Phillipson EA | title=Breathing Disorders in Sleep | publisher=Saunders Ltd. | year=2001 | pages=[https://archive.org/details/breathingdisorde0000unse/page/80 80] | isbn=978-0-7020-2510-5 | url-access=registration | url=https://archive.org/details/breathingdisorde0000unse/page/80 }}</ref>

The low oxygen level leads to physiologic constriction of the pulmonary arteries to correct ventilation-perfusion mismatching, which puts excessive strain on the right side of the heart. When this leads to right-sided heart failure, it is known as ''[[cor pulmonale]]''.<ref name=Olson2005/> Symptoms of this disorder occur because the heart has difficulty pumping blood from the body through the lungs. Fluid may, therefore, accumulate in the skin of the legs in the form of [[edema]] (swelling), and in the abdominal cavity in the form of [[ascites]]; decreased exercise tolerance and exertional [[chest pain]] may occur. On [[physical examination]], characteristic findings are the presence of a raised [[jugular venous pressure]], a palpable parasternal heave, a [[heart murmur]] due to [[tricuspid insufficiency|blood leaking through the tricuspid valve]], [[hepatomegaly]] (an enlarged liver), [[ascites]] and leg edema.<ref>{{cite book |author=Braunwald E |veditors=Kasper DL, Braunwald E, Fauci AS |title=Harrison's Principles of Internal Medicine|edition=16th |year=2005 |publisher=McGraw-Hill |location=New York, NY |isbn=978-0-07-139140-5 |pages=1367–78 |chapter=Chapter 216: heart failure and cor pulmonale|display-editors=etal}}</ref> Cor pulmonale occurs in about a third of all people with OHS.<ref name=Mokhlesi/>

==Mechanism==
It is not fully understood why some obese people develop obesity hypoventilation syndrome while others do not. It is likely the result of an interplay of various processes. Firstly, work of breathing is increased as [[adipose tissue]] restricts the normal movement of the chest muscles and makes the chest wall less [[Compliance (physiology)|compliant]], the [[Thoracic diaphragm|diaphragm]] moves less effectively, respiratory muscles are fatigued more easily, and airflow in and out of the lung is impaired by excessive tissue in the head and neck area. Hence, people with obesity need to expend more energy to breathe effectively.<ref name="Bray">{{cite book | last=Bray | first=GA |author2=Bouchard C |author3=James WPT | title=Handbook of Obesity | publisher=Marcel Dekker Inc. | year=1998 | pages=726 | isbn=978-0-8247-9899-4 }}</ref><ref name="Bjorntorp">{{cite book | last=Björntorp | first=P |author2=Brodoff BN | title=Obesity | publisher=JB Lippincott | year=1992 | pages=569 | isbn=978-0-397-50999-7 }}</ref> These factors together lead to sleep-disordered breathing and inadequate removal of carbon dioxide from the circulation and hence hypercapnia; given that carbon dioxide in aqueous solution combines with water to form an acid (CO2[g] + H2O[l] + excess H2O[l] --> H2CO3[aq]), this causes [[acidosis]] (increased acidity of the blood). Under normal circumstances, [[central chemoreceptors]] in the [[brain stem]] detect the acidity and respond by increasing the [[respiratory rate]]; in OHS, this "ventilatory response" is blunted.<ref name=Mokhlesi/><ref name=Piper>{{cite journal |vauthors=Piper AJ, Grunstein RR |title=Current perspectives on the obesity hypoventilation syndrome |journal=Current Opinion in Pulmonary Medicine |volume=13 |issue=6 |pages=490–6 |date=November 2007 |pmid=17901754 |doi=10.1097/MCP.0b013e3282ef6894|s2cid=32488927 }}</ref>

The blunted ventilatory response is attributed to several factors. Obese people tend to have raised levels of the hormone [[leptin]], which is secreted by adipose tissue and, under normal circumstances, increases ventilation. In OHS, this effect is reduced.<ref name=Mokhlesi/><ref name=Piper/> Furthermore, episodes of nighttime acidosis (e.g., due to sleep apnea) lead to [[renal compensation|compensation by the kidneys]] with retention of the [[alkali]] [[bicarbonate]]. This normalizes the blood's [[pH]]. However, bicarbonate stays around in the bloodstream for longer, and further episodes of hypercapnia lead to relatively mild acidosis and reduced ventilatory response in a [[Virtuous circle and vicious circle|vicious circle]].<ref name=Mokhlesi/><ref name=Piper/>

Low oxygen levels lead to [[hypoxic pulmonary vasoconstriction]], the tightening of small blood vessels in the lung to create an optimal distribution of blood through the lung. Persistently low oxygen levels causing chronic vasoconstriction lead to increased pressure on the [[pulmonary artery]] ([[pulmonary hypertension]]), which in turn puts strain on the [[right ventricle]], the part of the heart that pumps blood to the lungs. The right ventricle undergoes [[Ventricular remodeling|remodeling]], becomes distended, and is less able to remove blood from the veins. When this is the case, raised [[hydrostatic pressure]] leads to accumulation of fluid in the skin (edema), and in more severe cases, the liver and the abdominal cavity.<ref name=Mokhlesi/>

The chronically low oxygen levels in the blood also lead to increased release of [[erythropoietin]] and the activation of [[erythropoeisis]], the production of [[red blood cell]]s. This results in [[polycythemia]], abnormally increased numbers of circulating red blood cells and an elevated [[hematocrit]].<ref name=Mokhlesi/>

==Diagnosis==
Formal criteria for diagnosis of OHS are:<ref name=Olson2005/><ref name=Mokhlesi/><ref name=Sleep1999>{{cite journal |author=Anonymous |title=Sleep-related breathing disorders in adults: recommendations for syndrome definition and measurement techniques in clinical research. The Report of an American Academy of Sleep Medicine Task Force |journal=Sleep |volume=22 |issue=5 |pages=667–89 |year=1999 |pmid=10450601 |doi=10.1093/sleep/22.5.667|doi-access=free }}</ref>
* [[Body mass index]] over 30 kg/m2 (a measure of obesity, obtained by taking one's weight in kilograms and dividing it by one's height in meters squared)
* Arterial carbon dioxide level over 45 [[Torr|mmHg]] or 6.0 [[Pascal (unit)|kPa]] as determined by [[arterial blood gas]] measurement
* No alternative explanation for hypoventilation, such as use of [[narcotic]]s, severe [[obstructive lung disease|obstructive]] or [[interstitial lung disease]], severe chest wall disorders such as [[kyphoscoliosis]], severe [[hypothyroidism]] (underactive thyroid), [[neuromuscular disease]] or [[congenital central hypoventilation syndrome]]

If OHS is suspected, various tests are required to confirm it. The most important initial test is the demonstration of elevated carbon dioxide in the blood. This requires an [[arterial blood gas]] determination, which involves taking a blood sample from an [[artery]], usually the [[radial artery]]. Given that it would be complicated to perform this test on every patient with sleep-related breathing problems, some suggest that measuring bicarbonate levels in normal (venous) blood would be a reasonable screening test. If this is elevated (27 mmol/L or higher), blood gases should be measured.<ref name=Mokhlesi/>

To distinguish various subtypes, [[polysomnography]] is required. This usually requires brief admission to a hospital with a specialized sleep medicine department where several different measurements are conducted while the subject is asleep; this includes [[electroencephalography]] (electronic registration of electrical activity in the brain), [[electrocardiography]] (same for electrical activity in the heart), [[pulse oximeter|pulse oximetry]] (measurement of oxygen levels) and often other modalities.<ref name=Olson2005/> Blood tests are also recommended for the identification of [[hypothyroidism]] and [[polycythemia]].<ref name=Olson2005/><ref name=Mokhlesi/>

To distinguish between OHS and various other lung diseases that can cause similar symptoms, [[medical imaging]] of the lungs (such as a [[chest X-ray]] or [[Computed tomography|CT/CAT scan]]), [[spirometry]], electrocardiography and [[echocardiography]] may be performed. Echo- and electrocardiography may also show strain on the right side of the heart caused by OHS, and spirometry may show a [[restrictive lung disease|restrictive]] pattern related to obesity.<ref name=Mokhlesi/>

=== Classification ===
Obesity hypoventilation syndrome is a form of [[sleep disordered breathing]]. Two subtypes are recognized, depending on the nature of disordered breathing detected on further investigations. The first is OHS in the context of obstructive sleep apnea; this is confirmed by the occurrence of 5 or more episodes of apnea, hypopnea, or respiratory-related arousals per hour (high [[apnea-hypopnea index]]) during sleep. The second is OHS primarily due to "sleep hypoventilation syndrome"; this requires a rise of CO2 levels by 10 mmHg (1.3 kPa) after sleep compared to awake measurements and overnight drops in oxygen levels without simultaneous apnea or hypopnea.<ref name=Olson2005/><ref name=Sleep1999/> Overall, 90% of all people with OHS fall into the first category, and 10% into the second.<ref name=Mokhlesi/>

==Treatment==
In people with stable OHS, the most important treatment is [[Weight loss#Intentional|weight loss]]—by diet, through [[physical exercise|exercise]], with medication, or sometimes [[bariatric surgery|weight loss surgery]] (bariatric surgery). This has been shown to improve the symptoms of OHS and the resolution of the high carbon dioxide levels. Weight loss may take a long time and is not always successful.<ref name=Olson2005/> If the symptoms are significant, nighttime [[positive airway pressure]] (PAP) treatment is tried; this involves the use of a machine to assist with breathing. PAP exists in various forms, and the ideal strategy is uncertain. Some medications have been tried to stimulate breathing or correct underlying abnormalities; their benefit is again uncertain.<ref name=Mokhlesi/>

While many people with obesity hypoventilation syndrome are cared for on an outpatient basis, some deteriorate suddenly and, when admitted to the hospital, may show severe abnormalities such as markedly deranged blood acidity (pH<7.25) or depressed [[level of consciousness]] due to very high carbon dioxide levels. On occasions, admission to an [[intensive care unit]] with [[intubation]] and [[mechanical ventilation]] is necessary. Otherwise, "bi-level" positive airway pressure (see the next section) is commonly used to stabilize the patient, followed by conventional treatment.<ref>{{cite journal |vauthors=Mokhlesi B, Kryger MH, Grunstein RR |title=Assessment and management of patients with obesity hypoventilation syndrome |journal=Proc Am Thorac Soc |volume=5 |issue=2 |pages=218–25 |date=February 2008 |pmid=18250215 |doi=10.1513/pats.200708-122MG |pmc=2645254 }}</ref>

===Positive airway pressure===
[[Positive airway pressure]], initially in the form of continuous positive airway pressure (CPAP), is a useful treatment for obesity hypoventilation syndrome, particularly when obstructive sleep apnea coexists. CPAP requires the use during sleep of a machine that delivers a continuous positive pressure to the airways and preventing the collapse of soft tissues in the throat during breathing; it is administered through a mask on either the mouth and nose together or if that is not tolerated, on the nose only (nasal CPAP). This relieves the features of obstructive sleep apnea and is often sufficient to remove the resultant accumulation of carbon dioxide. The pressure is increased until the obstructive symptoms (snoring and periods of apnea) have disappeared. CPAP alone is effective in more than 50% of people with OHS.<ref name=Mokhlesi/>

On some occasions, the oxygen levels are persistently too low ([[Oxygen-haemoglobin dissociation curve|oxygen saturations]] below 90%). In that case, the hypoventilation itself may be improved by switching from CPAP treatment to an alternate device that delivers "bi-level" positive pressure: higher pressure during inspiration (breathing in) and a lower pressure during expiration (breathing out). If this too is ineffective in increasing oxygen levels, the addition of [[oxygen therapy]] may be necessary. As a last resort, [[tracheostomy]] may be necessary; this involves making a surgical opening in the trachea to bypass obesity-related airway obstruction in the neck. This may be combined with mechanical ventilation with an assisted breathing device through the opening.<ref name=Mokhlesi/>

===Other treatments===
People who fail first-line treatments or have very severe, life-threatening disease may sometimes be treated with [[tracheotomy]], which is a reversible procedure.<ref>Martin TJ, Badr M Safwan, and Finlay G. Treatment and prognosis of the obesity hypoventilation syndrome. UpToDate Aug 6, 2019. https://www.uptodate.com/contents/treatment-and-prognosis-of-the-obesity-hypoventilation-syndrome</ref> Treatments without proven benefit, and concern for harm, include oxygen alone or respiratory stimulant medications. [[Medroxyprogesterone acetate]], a [[progestin]], and [[acetazolamide]] are both associated with an increased risk of [[thrombosis]] and are not recommended.<ref name=Olson2005/><ref name=Mokhlesi/>

==Prognosis==
Obesity hypoventilation syndrome is associated with a reduced [[quality of life]], and people with the condition incur increased healthcare costs, largely due to hospital admissions, including observation and treatment on [[intensive care unit]]s. OHS often occurs together with several other disabling medical conditions, such as [[asthma]] (in 18–24%) and [[diabetes mellitus type 2|type 2 diabetes]] (in 30–32%). Its main complication of heart failure affects 21–32% of patients.<ref name=Mokhlesi/>

Those with abnormalities severe enough to warrant treatment have an increased risk of death reported to be 23% over 18 months and 46% over 50 months. This risk is reduced to less than 10% in those receiving treatment with PAP. Treatment also reduces the need for hospital admissions and reduces healthcare costs.<ref name=Mokhlesi/>

==Epidemiology==
The exact prevalence of obesity hypoventilation syndrome is unknown, and it is thought that many people with symptoms of OHS have not been diagnosed.<ref name=Olson2005/> About a third of all people with morbid obesity (a [[body mass index]] exceeding 40 kg/m2) have elevated [[carbon dioxide]] levels in the blood.<ref name=Mokhlesi/>

When examining groups of people with obstructive sleep apnea, researchers have found that 10–20% of them meet the criteria for OHS as well. The risk of OHS is much higher in those with more severe obesity, i.e., a body mass index (BMI) of 40 kg/m2 or higher. It is twice as common in men compared to women. The average age at diagnosis is 52. American [[Black people]] are more likely to be obese than American whites, and are therefore more likely to develop OHS, but obese Asians are more likely than people of other ethnicities to have OHS at a lower BMI as a result of physical characteristics.<ref name=Mokhlesi/>

It is anticipated that rates of OHS will rise as the prevalence of obesity rises. This may also explain why OHS is more commonly reported in the [[United States]], where obesity is more common than in other countries.<ref name=Mokhlesi/>

==History==
The discovery of obesity hypoventilation syndrome is generally attributed to the authors of a 1956 report of a professional [[poker]] player who, after gaining weight, became somnolent and fatigued and prone to fall asleep during the day, as well as developing [[edema]] of the legs suggesting [[heart failure]]. The authors coined the condition "Pickwickian syndrome" after the character Joe from [[Charles Dickens|Dickens']] ''[[The Pickwick Papers|The Posthumous Papers of the Pickwick Club]]'' (1837), who was markedly obese and tended to fall asleep uncontrollably during the day.<ref>{{cite journal |vauthors=Burwell CS, Robin ED, Whaley RD, Bicklemann AG |title=Extreme obesity associated with alveolar hypoventilation; a Pickwickian syndrome |journal=Am. J. Med. |volume=21 |issue=5 |pages=811–8 |year=1956 |pmid=13362309|doi=10.1016/0002-9343(56)90094-8}} Reproduced in {{cite journal |vauthors=Burwell CS, Robin ED, Whaley RD, Bickelmann AG |title=Extreme obesity associated with alveolar hypoventilation--a Pickwickian Syndrome |journal=Obes. Res. |volume=2 |issue=4 |pages=390–7 |year=1994 |pmid=16353591 |doi=10.1002/j.1550-8528.1994.tb00084.x}}</ref> This report, however, was preceded by other descriptions of hypoventilation in obesity.<ref name=Mokhlesi/><ref>{{cite journal |vauthors=Auchincloss JH, Cook E, Renzetti AD |title=Clinical and physiological aspects of a case of obesity, polycythemia and alveolar hypoventilation |journal=J. Clin. Invest. |volume=34 |issue=10 |pages=1537–45 |date=October 1955 |pmid=13263434 |pmc=438731 |doi=10.1172/JCI103206 }}</ref> In the 1960s, various further discoveries were made that led to the distinction between obstructive sleep apnea and sleep hypoventilation.<ref name="Pack AI 7–15">{{cite journal |author=Pack AI |title=Advances in sleep-disordered breathing |journal=Am. J. Respir. Crit. Care Med. |volume=173 |issue=1 |pages=7–15 |date=January 2006 |pmid=16284108 |doi=10.1164/rccm.200509-1478OE |url=http://ajrccm.atsjournals.org/cgi/content/full/173/1/7 |access-date=2008-11-23 |archive-date=2011-09-27 |archive-url=https://web.archive.org/web/20110927231957/http://ajrccm.atsjournals.org/cgi/content/full/173/1/7 |url-status=dead |url-access=subscription }}</ref>

The term "Pickwickian syndrome" has fallen out of favor because it does not distinguish obesity hypoventilation syndrome and sleep apnea as separate disorders (which may coexist).<ref name="Pack AI 7–15"/><ref>{{cite journal |last1=Bray |first1=George A. |title=What's in a Name? Mr. Dickens' "Pickwickian" Fat Boy Syndrome |journal=Obesity Research |date=July 1994 |volume=2 |issue=4 |pages=380–383 |doi=10.1002/j.1550-8528.1994.tb00079.x|pmid=16353586 |doi-access=free }}</ref>

==References==
{{Reflist}}

==Further reading==
*{{cite journal |last1=Mokhlesi |first1=B |last2=Masa |first2=JF |last3=Brozek |first3=JL |last4=Gurubhagavatula |first4=I |last5=Murphy |first5=PB |last6=Piper |first6=AJ |last7=Tulaimat |first7=A |last8=Afshar |first8=M |last9=Balachandran |first9=JS |last10=Dweik |first10=RA |last11=Grunstein |first11=RR |last12=Hart |first12=N |last13=Kaw |first13=R |last14=Lorenzi-Filho |first14=G |last15=Pamidi |first15=S |last16=Patel |first16=BK |last17=Patil |first17=SP |last18=Pépin |first18=JL |last19=Soghier |first19=I |last20=Tamae Kakazu |first20=M |last21=Teodorescu |first21=M |title=Evaluation and Management of Obesity Hypoventilation Syndrome. An Official American Thoracic Society Clinical Practice Guideline. |journal=American Journal of Respiratory and Critical Care Medicine |date=1 August 2019 |volume=200 |issue=3 |pages=e6–e24 |doi=10.1164/rccm.201905-1071ST |pmid=31368798|pmc=6680300 }}
{{Medical resources
| DiseasesDB = 32243
| ICD10 = {{ICD10|E|66|2|e|65}}
| ICD9 = {{ICD9|278.03}}
| OMIM = 257500
| MedlinePlus = 000085
| eMedicineSubj = ped
| eMedicineTopic = 1627
| eMedicine_mult = {{eMedicine2|med|3470}}
| MeshID = D010845
}}
{{Obesity|state=expanded}}
{{SleepSeries2}}
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[[Category:Medical conditions related to obesity]]
[[Category:Sleep disorders]]
[[Category:Respiratory diseases]]
[[Category:Syndromes affecting the respiratory system]]