Inappropriate sinus tachycardia: Difference between revisions
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*Normal [[P wave]] morphology | *Normal [[P wave]] morphology | ||
*A resting [[sinus tachycardia]] is usually (but not always) present | *A resting [[sinus tachycardia]] is usually (but not always) present | ||
*A nocturnal reduction in [[heart rate]] | *A nocturnal reduction in [[heart rate]] from over 100 beats per minute to 80 - 90 beats per minute | ||
*There is an inappropriate [[heart rate]] response on exertion | *There is an inappropriate [[heart rate]] response on exertion so that the heart rate accelerates to 140 - 150 beats per minute with minimal exertion. | ||
*The mean [[heart rate]] during 24 hrs of monitoring is > 95 bpm | *The mean [[heart rate]] during 24 hrs of monitoring is > 95 bpm | ||
*Symptoms are documented to be due to [[tachycardia]] | *Symptoms are documented to be due to [[tachycardia]] | ||
Revision as of 00:41, 10 September 2012
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords: IST; chronic nonparoxysmal sinus tachycardia
Overview
Inappropriate sinus tachycardia is an uncommon form of supraventricular tachycardia (SVT).
Pathophysiology
The mechanism of the arrhythmia primarily involves the sinus node and peri-nodal tissue[1] and does not require the 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.[2][3]
Epidemiology and Demographics
The disorder is uncommon.
Sex
More common in women.
Age
Most patients are in their late 20s to early 30s.
Diagnosis
No formal diagnostic criteria exist. A diagnosis of Inappropriate sinus tachycardia is primarily a diagnosis of exclusion and the following must 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
- A nocturnal reduction in heart rate from over 100 beats per minute to 80 - 90 beats per minute
- There is an inappropriate heart rate response on exertion so that the heart rate accelerates to 140 - 150 beats per minute with minimal exertion.
- The mean heart rate during 24 hrs of monitoring is > 95 bpm
- Symptoms are documented to be due to tachycardia
- Hypotension may occasionally be observed
- Syncope (fainting) is occasionally reported
Symptoms
Symptoms reported by patients vary in frequency and severity. Symptoms associated with Inappropriate sinus tachycardia include:
- Blurred vision
- Frequent palpitations
- Dyspnea (shortness of breath) and palpitations on exertion
- Pre-syncope (feeling as if about to faint)
- Fatigue
- Dizziness
- Exercise intolerance
- Occasional paresthesia and cramping
- Symptoms associated with autonomic nervous system disturbance, including GI disturbance
- Orthostatic hypotension with a drop in blood pressure on standing
Treatment
Treatments in the form of pharmacological therapy or catheter ablation are available, although it is currently difficult to treat successfully. 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, 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 (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).
See also
- Supraventricular tachycardia
- Sinus tachycardia
- Postural orthostatic tachycardia syndrome
- Dysautonomia
References
- ↑ Sato, Toshiaki; Mitamura, Hideo; Murata, Mitsushige; Shinagawa, Kaori; Miyoshi, Shunichiro; Kanki, Hideaki; Takatsuki, Seiji; Soejima, Kyoko; Miyazaki, Toshihisa (2000). "Electrophysiologic findings of a patient with inappropriate sinus tachycardia cured by selective radiofrequency catheter ablation". Journal of Electrocardiology. 33 (4): 381–6. doi:10.1054/jelc.2000.9648. PMID 11099363.
- ↑ Chiale, Pablo A.; Garro, Hugo A.; Schmidberg, Jorge; Sánchez, Rubén A.; Acunzo, Rafael S.; Lago, Manuel; Levy, Gabriela; Levin, Mariano (2006). "Inappropriate sinus tachycardia may be related to an immunologic disorder involving cardiac β andrenergic receptors". Heart Rhythm. 3 (10): 1182–6. doi:10.1016/j.hrthm.2006.06.011. PMID 17018348.
- ↑ Nattel, Stanley (2006). "Inappropriate sinus tachycardia and beta-receptor autoantibodies: A mechanistic breakthrough?". Heart Rhythm. 3 (10): 1187–8. doi:10.1016/j.hrthm.2006.07.019. PMID 17018349.
Sources
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. Medline Abstract
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. Circulation Abstract
Yusuf S, Camm AJ. Deciphering the sinus tachycardias. Clin Cardiol. 2005 Jun;28(6):267-76. Review. 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. 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. 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. 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. 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. Full Text Article