Inappropriate Sinus Tachycardia (IST) is a rare type of cardiac arrhythmia, within the category of supraventricular tachycardia (SVT), although doctors believe it stems from dysautonomia, a disturbance and/or failure of the autonomic nervous system.
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[1] and does not require the AV node for maintenance. Treatments in the form of pharmacological therapy or catheter ablation are available, although it is currently difficult to treat successfully.
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Symptoms reported by patients vary in frequency and severity.
Symptoms associated with IST include:
No formal diagnostic criteria exist. A diagnosis of Inappropriate sinus tachycardia is primarily one of exclusion and the following may be observed:
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 blockers, selective sinus node If channel inhibitors (ivabradine)[2], calcium channel blockers and antiarrhythmic agents. 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 blockers. 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[3] (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).
Yusuf S, Camm AJ (June 2005). "Deciphering the sinus tachycardias". Clin Cardiol 28 (6): 267–76. doi:10.1002/clc.4960280603. PMID 16028460.
Still AM, Raatikainen P, Ylitalo A, et al. (March 2005). "Prevalence, characteristics and natural course of inappropriate sinus tachycardia". Europace 7 (2): 104–12. doi:10.1016/j.eupc.2004.12.007. PMID 15763524. http://europace.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=15763524.
Leon H, Guzman JC, Kuusela T, Dillenburg R, Kamath M, Morillo CA (January 2005). "Impaired baroreflex gain in patients with inappropriate sinus tachycardia". J. Cardiovasc. Electrophysiol. 16 (1): 64–8. doi:10.1046/j.1540-8167.2005.04441.x. PMID 15673390. http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1045-3873&date=2005&volume=16&issue=1&spage=64.
Sánchez-Quintana D, Cabrera JA, Farré J, Climent V, Anderson RH, Ho SY (February 2005). "Sinus node revisited in the era of electroanatomical mapping and catheter ablation". Heart 91 (2): 189–94. doi:10.1136/hrt.2003.031542. PMC 1768731. PMID 15657230. http://heart.bmj.com/cgi/pmidlookup?view=long&pmid=15657230.
Cruz Filho FE, Maia IG, Fagundes ML, Boghossian S, Ribeiro JC (March 1998). "[Sinus node modification by catheter using radiofrequency current in a patient with inappropriate sinus tachycardia. Evaluation of early and late results]" (in Portuguese). Arq. Bras. Cardiol. 70 (3): 173–6. PMID 9674178.
Lee SH, Cheng JJ, Kuan P, Hung CR (1997). "Radiofrequency Catheter Modification of Sinus Node for Inappropriate Sinus Tachycardia: A Case Report". Chin Med J (Taipei) 60: 117–23. http://www.vghtpe.gov.tw/~cmj/6002/600210.htm.
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