Inappropriate sinus tachycardia 3625909 164485501 2007-10-14T12:35:07Z FRANHORNE 755787 /* Treatment */ '''Inappropriate sinus tachycardia''' ('''IST''') is an uncommon type of [[cardiac arrhythmia]], within the category of [[supraventricular tachycardia]] ('''SVT'''). The mechanism and primary [[etiology]] of Inappropriate sinus tachycardia has not been fully elucidated. The mechanism of the arrhythmia primarily involves the [[Sinus Node]] and peri-nodal tissue{{fn|1}} and does not require the AV Node ([[Atrioventricular node]]) for maintenance. Treatments in the form of [[pharmacological]] therapy or [[Catheter ablation]] are available, although it is currently difficult to treat successfully. == Symptoms == Symptoms reported by patients vary in frequency and severity. Symptoms associated with Inappropriate sinus tachycardia include: *Frequent [[Palpitations]] *[[Dyspnea]] (Shortness of Breath) and [[Palpitations]] on exertion *Pre-[[Syncope]] (feeling as if about to faint) *[[Fatigue (physical)]] *[[Dizziness]] *Exercise intolerance *Occasional [[Paresthesia]] and cramping *Symptoms associated with [[Autonomic nervous system]] disturbance, including GI disturbance == Diagnosis == No formal diagnostic criteria exist. A diagnosis of Inappropriate sinus tachycardia is primarily one of exclusion and the following may be observed: *Exclusion of all other causes of [[Sinus tachycardia]] *Common forms of [[Supraventricular tachycardia]] (SVT) must be excluded *Normal P wave morphology *A resting [[Sinus tachycardia]] is usually (but not always) present *Nocturnal dip in [[Heart rate]] *Inappropriate [[Heart rate]] response on exertion *Mean [[Heart rate]] in 24hrs >95bpm *Symptoms are documented to be due to [[tachycardia]] *Hypotension is occasionally observed *[[Syncope]] ([[fainting]]) is occasionally reported == Treatment == IST has been treated both pharmacologically and invasively, with varying degrees of success. Some types of medication tried by cardiologists and other physicians include: [[Beta blocker]]s, [[Calcium channel blocker]]s and [[Antiarrhythmic agent]]s. Some [[SSRI]] drugs are also occasionally tried and also treatments more commonly used to treat [[Postural orthostatic tachycardia syndrome]] such as [[Fludrocortisone]]. This approach is very much "trial-and-error". Patients with IST are often intolerant to [[Beta blocker]]s. A new selective sinus node inhibitor [[Ivabradine]] is also being used to treat IST. Invasive treatments include forms of [[Catheter ablation]] such as '''Sinus Node Modification'''{{fn|2}} (selective ablation of the Sinus Node), '''Complete Sinus Node Ablation''' (with associated implantation of a Permanent [[Artificial pacemaker]]) and '''AV Node Ablation''' in very resistant cases (creation of [[iatrogenic]] [[complete heart block]], necessitating implantation of a Permanent [[Artificial pacemaker]]). == External links == *[http://heartdisease.about.com/cs/arrhythmias/a/IST.htm Inappropriate sinus tachycardia] by Dr Rich Fogoros *[http://www.geocities.com/inappropriatesinustachy/ Inappropriate Sinus Tachycardia - Info & Support] *[http://www.arrhythmiaalliance.org.uk/ Arrhythmia Alliance] *[http://www.supportdysautonomia.org/ Dysautonomia Support Network] == See also == *[[supraventricular tachycardia]] *[[Sinus tachycardia]] *[[Postural orthostatic tachycardia syndrome]] *[[Dysautonomia]] == References == {{fnb|1}} Sato T, Mitamura H, Murata M, Shinagawa K, Miyoshi S, Kanki H, Takatsuki S, Soejima K, Miyazaki T, Ogawa S. Electrophysiologic findings of a patient with inappropriate sinus 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] {{fnb|2}}Lee RJ. Kalman JM. Fitzpatrick AP. Epstein LM. Fisher WG. Olgin JE. Lesh MD. Scheinman MM. Radiofrequency catheter modification of the sinus node 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] 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] 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] 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] 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] Cruz Filho FE, Maia IG, Fagundes ML, Boghossian S, Ribeiro JC. 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] 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] [[Category:Cardiac electrophysiology]]