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| {{SI}} | | __NOTOC__ |
| {{CMG}} | | '''For patient information, click [[Inappropriate sinus tachycardia (patient information)|here]]''' |
| | {{Inappropriate sinus tachycardia}} |
| | {{CMG}} |
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| {{SK}} IST; chronic nonparoxysmal sinus tachycardia | | {{SK}} IST; chronic nonparoxysmal sinus tachycardia |
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| ==Overview== | | == [[Inappropriate sinus tachycardia overview|Overview]] == |
| '''Inappropriate sinus tachycardia''' is an uncommon form of [[supraventricular tachycardia]] ('''[[SVT]]''').
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| ==Historical Perspective== | | == [[Inappropriate sinus tachycardia historical perspective|Historical Perspective]] == |
| The condition was first formally recognized as a veritable syndrome in 1979.
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| ==Pathophysiology== | | == [[Inappropriate sinus tachycardia pathophysiology|Pathophysiology]] == |
| The mechanism of the arrhythmia primarily involves the [[sinus node]] and peri-nodal tissue<ref>{{cite journal |doi=10.1054/jelc.2000.9648 |title=Electrophysiologic findings of a patient with inappropriate sinus tachycardia cured by selective radiofrequency catheter ablation |year=2000 |last1=Sato |first1=Toshiaki |last2=Mitamura |first2=Hideo |last3=Murata |first3=Mitsushige |last4=Shinagawa |first4=Kaori |last5=Miyoshi |first5=Shunichiro |last6=Kanki |first6=Hideaki |last7=Takatsuki |first7=Seiji |last8=Soejima |first8=Kyoko |last9=Miyazaki |first9=Toshihisa |journal=Journal of Electrocardiology |volume=33 |issue=4 |pages=381–6 |pmid=11099363}}</ref> and does not require the [[Atrioventricular node|AV node]] for maintenance. These patients have no apparent heart disease or other causes of sinus tachycardia. IST is thought to be due to abnormal autonomic control or [[dysautonomia]]. An autoimmune mechanism has been suggested as several studies have detected autoantibodies that activate beta adrenoreceptors in a portion of patients.<ref>{{cite journal |doi=10.1016/j.hrthm.2006.06.011 |title=Inappropriate sinus tachycardia may be related to an immunologic disorder involving cardiac β andrenergic receptors |year=2006 |last1=Chiale |first1=Pablo A. |last2=Garro |first2=Hugo A. |last3=Schmidberg |first3=Jorge |last4=Sánchez |first4=Rubén A. |last5=Acunzo |first5=Rafael S. |last6=Lago |first6=Manuel |last7=Levy |first7=Gabriela |last8=Levin |first8=Mariano |journal=Heart Rhythm |volume=3 |issue=10 |pages=1182–6 |pmid=17018348}}</ref><ref>{{cite journal |doi=10.1016/j.hrthm.2006.07.019 |title=Inappropriate sinus tachycardia and beta-receptor autoantibodies: A mechanistic breakthrough? |year=2006 |last1=Nattel |first1=Stanley |journal=Heart Rhythm |volume=3 |issue=10 |pages=1187–8 |pmid=17018349}}</ref>
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| ==Epidemiology and Demographics== | | == [[Inappropriate sinus tachycardia causes|Causes]] == |
| The disorder is uncommon.
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| ===Sex=== | | == [[Inappropriate sinus tachycardia differential diagnosis|Differentiating Inappropriate Sinus Tachycardia from other Diseases]] == |
| More common in women.
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| ===Age=== | | == [[Inappropriate sinus tachycardia epidemiology and demographics|Epidemiology and Demographics]] == |
| Most patients are in their late 20s to early 30s.
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| ==Differentiating Inappropriate Sinus Tachycardia from other Medical Conditions== | | == Diagnosis == |
| The following medical conditions must be excluded as a cause of tachycardia:
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| *[[Diabetes]]-induced [[autonomic dysfunction]]
| | [[Inappropriate sinus tachycardia diagnostic criteria|Diagnostic Criteria]] | [[Inappropriate sinus tachycardia history and symptoms|History and Symptoms]] | [[Inappropriate sinus tachycardia electrocardiogram|Electrocardiogram]] |
| *[[Hyperthyroidism]]
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| *[[Pheochromocytoma]]
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| *[[Substance abuse]]
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| ==Differentiating Inappropriate Sinus Tachycardia from other Supraventricular Arrhythmias==
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| ==Diagnosis==
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| ===Diagnostic Criteria===
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| No formal diagnostic criteria exist. A diagnosis of Inappropriate sinus tachycardia is primarily a diagnosis of exclusion and the following must be observed:
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| *Exclusion of all other causes of [[sinus tachycardia]]
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| *Common forms of [[supraventricular tachycardia]] (SVT) must be excluded
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| *Normal [[P wave]] morphology
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| *A resting [[sinus tachycardia]] is usually (but not always) present
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| *A nocturnal reduction in [[heart rate]] from over 100 beats per minute to 80 - 90 beats per minute
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| *There is an inappropriate [[heart rate]] response on exertion so that the heart rate accelerates to 140 - 150 beats per minute with minimal exertion.
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| *The mean [[heart rate]] during 24 hrs of monitoring is > 95 bpm
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| *Symptoms are documented to be due to [[tachycardia]]
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| *[[Hypotension]] may occasionally be observed
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| *[[Syncope]] ([[fainting]]) is occasionally reported
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| === Symptoms ===
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| Symptoms reported by patients vary in frequency and severity. Symptoms associated with Inappropriate sinus tachycardia include:
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| *[[Blurred vision]]
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| *Frequent [[palpitations]]
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| *[[Dyspnea]] ([[shortness of breath]]) and [[palpitations]] on exertion
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| *[[Pre-syncope]] (feeling as if about to [[faint]])
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| *[[Fatigue]]
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| *[[Dizziness]]
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| *[[Exercise intolerance]]
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| *Occasional [[paresthesia]] and [[cramping]]
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| *Symptoms associated with [[autonomic nervous system]] disturbance, including GI disturbance
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| *[[Orthostatic hypotension]] with a [[drop in blood pressure on standing]]
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| == Treatment == | | == Treatment == |
| Treatments in the form of [[pharmacological]] therapy or [[catheter ablation]] are available, although it is currently difficult to treat successfully.
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| ===Beta-blockers===
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| In so far as the pathophysiology of IST involves abnormal sensitivity to [[adrenaline]], [[betaa-blockers]] can be helpful.
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| ===Calcium Channel Blockers===
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| Although [[calcium channel blockers]] slow conduction through the [[AV node]], they have been marginally effective in the treatment of IST.
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| ===Ivabradine===
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| A new selective sinus node inhibitor [[Ivabradine]] is also being used to treat IST.
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| ===Treatments Related to Dysautonomia and POTS===
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| In so far as the underlying pathophysiology may involve a [[dysautonomia]] and features of [[Postural orthostatic tachycardia syndrome]] ([[POTS]]), some therapies more commonly used to treat these disorders have been tried:
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| ====[[Fludrocortisone]] ([[Florinef]])====
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| [[POTS]] and [[dysautonomia]] have been associated with decreases in blood volume, and this drug promotes sodium retention.
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| ====[[Midodrine]]====
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| Midodrine increases vasoconstriction, and prevents falls in blood pressure.
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| ====[[Serotonin-reuptake inhibitors]] ([[SSRI]]s)====
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| SSRIs have proven effective in treating some patients with [[dysautonomia]].
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| ===Catheter Ablation===
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| Invasive treatments include forms of [[Catheter ablation]] has gained favor among electrophysiologists in the treatment of IST.
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| ====Sinus Node Modification====
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| This procedure involves selective ablation of the Sinus Node
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| ====Complete Sinus Node Ablation====
| | [[Inappropriate sinus tachycardia treatment guidelines|ACC/AHA/ESC Treatment Guidelines]] | [[Inappropriate sinus tachycardia medical therapy|Medical Therapy]] | [[Inappropriate sinus tachycardia surgery|Surgery]] |
| This procedure requires implantation of a Permanent [[Artificial pacemaker]])
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| ====AV Node Ablation==== | | ==Case Studies== |
| In cases resistant to sinus node ablation, AV node ablation with creation of an [[iatrogenic]] [[complete heart block]], may be neccessary. This procedure requires implantation of a permanent [[artificial pacemaker]]).
| | [[Inappropriate sinus tachycardia case study one|Case #1]] |
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| == See also == | | ==Related Chapters== |
| *[[Supraventricular tachycardia]] | | *[[Supraventricular tachycardia]] |
| *[[Sinus tachycardia]] | | *[[Sinus tachycardia]] |
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| *[[Dysautonomia]] | | *[[Dysautonomia]] |
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| ==References==
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| {{Reflist|2}}
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| == Sources ==
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| Sato T, Mitamura H, Murata M, Shinagawa K, Miyoshi S, Kanki H,
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| Takatsuki S, Soejima K, Miyazaki T, Ogawa S. Electrophysiologic findings of a patient with inappropriate sinus
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| tachycardia cured by selective radiofrequency catheter ablation. J Electrocardiol. 2000 Oct;33(4):381-6. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11099363&dopt=Abstract Medline Abstract]
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| Lee RJ. Kalman JM. Fitzpatrick AP. Epstein LM. Fisher WG. Olgin JE.
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| Lesh MD. Scheinman MM. Radiofrequency catheter modification of the sinus node
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| for "inappropriate" sinus tachycardia. Circulation. 92(10):2919-28, 1995. [http://circ.ahajournals.org/cgi/content/abstract/92/10/2919?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Radiofrequency+catheter+modification+of+the+sinus+node+for+%22inappropriate%22+sinus&searchid=1048593786710_3685&stored_search=&FIRSTINDEX=0&search_url=http%3A%2F%2Fcirc.ahajournals.org%2Fcgi%2Fsearch&journalcode=circulationaha Circulation Abstract]
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| Yusuf S, Camm AJ. Deciphering the sinus tachycardias. Clin Cardiol. 2005 Jun;28(6):267-76. Review. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16028460&query_hl=6&itool=pubmed_docsum Medline Abstract]
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| AM Still, P Raatikainen, A Ylitalo, H Kauma, M Ikaheimo, Y Antero Kesaniemi, and HV Huikuri. Prevalence, characteristics and natural course of inappropriate sinus tachycardia. Europace, March 1, 2005; 7(2): 104-12. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15763524&query_hl=1&itool=pubmed_docsum Medline Abstract]
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| Leon H, Guzman JC, Kuusela T, Dillenburg R, Kamath M, Morillo CA. Impaired baroreflex gain in patients with inappropriate sinus tachycardia. J Cardiovasc Electrophysiol. 2005 Jan;16(1):64-8. Erratum in: J Cardiovasc Electrophysiol. 2005 Feb;16(2):109. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15673390&query_hl=4&itool=pubmed_docsum Medline Abstract]
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| Sanchez-Quintana D, Cabrera JA, Farre J, Climent V, Anderson RH, Ho SY. Sinus node revisited in the era of electroanatomical mapping and catheter ablation. Heart. 2005 Feb;91(2):189-94. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15657230&query_hl=4&itool=pubmed_docsum Medline Abstract]
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| Cruz Filho FE, Maia IG, Fagundes ML, Boghossian S, Ribeiro JC.
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| Arq Bras Cardiol. Sinus node modification by catheter using radiofrequency current in a patient with inappropriate sinus tachycardia. Evaluation of early and late results. 1998 Mar;70(3):173-6. Portuguese. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9674178&dopt=Abstract Medline Abstract]
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| Shih-Huang Lee1, Jun-Jack Cheng1, Peiliang Kuan1, Chi-Ren Hung. Radiofrequency Catheter Modification of Sinus Node for Inappropriate Sinus Tachycardia: A Case Report. Chin Med J (Taipei) ;60:117-23. 1997. [http://www.vghtpe.gov.tw/~cmj/6002/600210.htm Full Text Article]
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| {{Electrocardiography}} | | {{Electrocardiography}} |