Chronic Inappropriate Sinus Tachycardia in Elderly Females

Background: The vast majority of reports of inappropriate sinus tachycardia (IST) had included predominantly young females with ages ranging between 15 and 46 years. In contrast, the present study presents the findings in four elderly females (aged 61–71 years) with long‐standing symptoms of palpitations, more than 15 years, in whom IST was diagnosed in their 6^th or 7^th decade. Methods: Clinical and laboratory examinations including electrocardiograms, echocardiograms, and heart rate variability studies were retrospectively reviewed in four of the nine elderly female patients with long‐standing cardiac symptoms. Indices of heart rate variability were compared to four age‐matched asymptomatic elderly females with no structural heart disease. Results: The resting electrocardiograms were normal but one had voltage criteria for left ventricular hypertrophy. All traditional time‐ and frequency‐domain indices were significantly decreased in the symptomatic elderly females as compared to the controls. Echocardiograms showed normal ejection fraction, and in three patients evidence of diastolic dysfunction and mild left ventricular hypertrophy. Blood pressures were elevated, with systolic blood pressure ranging from 170 to 190 and diastolic blood pressure ranging from 94 to 106. Anxiety disorders were diagnosed in all patients. Conclusions: This study demonstrates that IST can be present in a wide spectrum of patient populations, including elderly populations. It seems that some cases of IST can become chronic if not treated adequately. Apparently, earlier identification and treatment could have improved the quality of life of the patients. Traditional HRV indices may not be valuable to support either a sympathetic or parasympathetic mechanism. Therefore, further studies should consider the potential usefulness of the nonlinear method such as, for example, approximate entropy and detrended fluctuation analysis.     

Inappropriate Sinus Tachycardia: Evaluation and Therapy

Inappropriate Sinus Tachycardia. Inappropriate sinus tachycardia is an ill-defined clinical syndrome characterized by an increased resting heart rate accompanied by an exaggerated response to exercise or stress. It is not associated with underlying structural heart disease. The mechanism may involve a primary abnormality of the sinus node demonstrating enhanced automaticity or, alternatively, a primary autonomic disturbance with increase sympathetic activity and enhanced sinus node β-adrenergic sensitivity. The diagnosis of inappropriate sinus tachycardia is one of exclusion. It is most common in young females, with a disproportionate number employed in the health care field. Autonomic and electrophysiologic testing may be required in selected individuals to clarify the mechanism and rule out sinus node reentry or right atrial tachycardia. Therapy of inappropriate sinus tachycardia is empiric. Pharmacologic approaches include beta blockers or verapamil. Radiofrequency catheter ablation of the superior portion of the sinus node shows promise as a useful alternative in patients with refractory symptoms.     

窦房结改良术治疗不适当的窦性心动过速(附一例报告)

报告１例不适当的窦性心动过速采用导管射频消融部分窦房结——窦房结改良术而成功治愈的病例。患者女性、６３岁。心动过速史３０余年。平时心率９０ｂｐｍ以上,交感兴奋时高达２１０ｂｐｍ。心电图示窦性Ｐ波。心内电生理检查为起源于窦房结区的自律性增高的心动过速。用温控大头电极在最早兴奋的窦房结区上部放电,每次放电后略调整大头电极位置,使消融面积增大。自第６次放电１０ｓ后Ａ波频率降低,但停止放电后又增快;直至第１６次放电停止后,Ａ波频率不再增快。观察３０ｍｉｎ,窦性心率从放电前２１０ｂｐｍ降至８２ｂｐｍ。术后停用一切药物,随访两个月,窦性心律７３～１２２ｂｐｍ,证实窦房结改良术成功。     

Inappropriate Sinus Tachycardia After Radiofrequency Ablation of Para-Hisian Accessory Pathways

Inappropriate Sinus Tachycardia After Catheter Ablation. Introduction : Inappropriate sinus tachycardia (IST) has been observed following radiofrequency ablation (RFA) of the AV nodal fast pathway. This study was aimed to prospectively analyze the incidence and clinical significance of IST following RFA of para-Hisian accessory pathways (APs).
Methods and Results : Twenty-eight patients (pts) with para-Hisian APs underwent RFA. An AP was defined as para-Hisian whenever its atrial and ventricular insertions were associated with a His-bundle potential ≥ 0.1 mV. RF current was always delivered at the atrial aspect of the tricuspid annulus. to a site where the His-bundle potential was < 0.15 mV. Time- and frequency-domain analysis of heart rate variability was performed in 22 patients, before and after RFA. Abolition of AP conduction was obtained in all pts, and no AV conduction alteration occurred. Six pts (21.4%) presented with IST 45 to 240 minutes after the ablation procedure. In 5 of them, IST disappeared spontaneously within 72 hours, whereas in 1 pt β-blockers were required for 2 months. The atrial potential amplitude (1.217 ± 0.264 mV vs 0.882 ± 0.173 mV, P = 0.009) and A/V potential amplitude ratio (2.633 vs 1.686, P = 0.05) were significantly higher in pts who developed IST than in those who did not. A marked decrease in heart rate variability was observed only in pts who developed IST.
Conclusion : IST is a relatively frequent complication after RFA of para-Hisian APs: it is generally short-lasting and usually does not require any treatment. IST after catheter ablation is likely to depend upon transient parasympathetic denervation of the sinus node.     

Experimental Model of Inappropriate Sinus Tachycardia: Initiation and Ablation

Objective: The purpose of the present study was to develop an experimental model of inappropriate sinus tachycardia (IST) by injecting a catecholamine into a fat pad containing autonomic ganglia (AG) innervating the sinus node (SN).Methods: Initial protocols in 3 groups of pentobarbital anesthetized dogs consisted of (1) slowing the heart rate (HR) by electrical stimulation of AG in the fat pad; (2) the effect of intravenous injection of epinephrine (0.1–0.3 mg) on the HR and systolic blood pressure (BP); (3) the response of SN rate to intravenously injected isoproterenol (1 μgm/kg). These studies established a reference for the response to epinephrine injection (mean dose 0.2 ± 0.9 mg, n = 14) into the fat pad at the base of the right superior pulmonary vein (RSPV). ECG leads, right atrial and His bundle electrograms, BP and core body temperature were continuously monitored.Results: Epinephrine, injected into the fat pad, caused a significant increase in heart rate (HR, average: 211 ± 11/min, p < 0.05 compared to control) but little change in systolic BP, 149 ± 10 mmHg, p = NS (Group I, N = 8). The tachycardia lasted >30 minutes. Ice mapping and P wave morphology showed the tachycardia origin in the SN in 6/8 and in the crista terminalis (CT) in 2. Injection of 0.4 cc of formaldehyde into the FP restored HR (159 ± 16) toward baseline (154 ± 18). In Group II (N = 6), the same regimen induced a significant increase in both HR and systolic BP (194 ± 17/min and 230 ± 24 mmHg, respectively) compared to control values (143 ± 23/min, 162 ± 24 mmHg) which lasted for > 30 minutes. Ice mapping and P wave morphology showed that the pacemaker was in the SN (1), overlying the CT (2), or atrioventricular junction (2). Formaldehyde (0.4 cc) injected into the FP restored both HR and systolic BP toward baseline values (148 ± 29/min and 152 ± 24 mmHg, p = NS) and prevented, slowing of the HR by electrical stimulation of the AG; moreover, the same dose of epinephrine injected intravenously increased HR and SBP but only for 2–5 minutes; Isoproterenol (1 μ g/kg) injected intravenously induced essentially the same increase in sinus rate after AG ablation as in the control state (194 ± 15/min vs 193 ± 23/min, p = NS).Conclusion: Experimental IST is mainly localized in the SN or CT. Ablation of the AG terminates IST without impairing the SN response to an adrenergic challenge.Supported by grants from the Helen and Wil Webster Arrhythmia Research Fund of the University of Oklahoma Foundation, Norman, Oklahoma and Roger and B. Ann Cole, Edmond, Oklahoma.Helen Webster Professor of Cardiac Arrhythmias, 1200 Everett Drive, Room TUH6E103, Oklahoma City, OK 73104.     

Radiofrequency Catheter Ablation Using Non-Contact Mapping for Inappropriate Sinus Tachycardia

INTRODUCTION: In this report we describe our experience using non-contact mapping for radiofrequency ablation in patients with inappropriate sinus tachycardia. METHODS AND RESULTS: Two female patients with persistent complaints of palpitations and documented inappropriate sinus tachycardia with failed medical management underwent radiofrequency ablation using non-contact mapping. Non-contact mapping provided a continuous determination of the site of earliest breakthrough, facilitating the delivery and the assessment of the results of each radiofrequency application. CONCLUSION: Non-contact mapping is an effective mapping modality in the interventional treatment of inappropriate sinus tachycardia.     

CARTO标测指导射频消融治疗不适当的窦性心动过速

一例 34岁女性患者心悸、胸闷 2年半。Holter示最大心率 176次 /分 ,平均心率 12 7次 /分 ,固有心率 12 6次 /分。在基础窦性心律、静脉滴注 (简称静滴 )异丙肾上腺素后及射频消融术后分别行CARTO标测。静滴异丙肾上腺素后 ,心率从 14 5次 /分增至 170次 /分 ,最早激动点沿界嵴向上移动 3mm。消融靶点 (静滴异丙肾上腺素后的最早心房激动点 )由CARTO标测定位。在释放 2 1次射频电流进行射频消融后 ,未静滴异丙肾上腺素的心率从术前的14 5次 /分降至 98次 /分 ,静滴异丙肾上腺素后的心率从术前的 170次 /分降至 14 0次 /分。Ⅱ、Ⅲ、aVF导联上的P波形态从明显直立变为低平。术后第 3天Holter示最大心率和平均心率分别为 12 5次 /分和 95次 /分 ;固有心率为94次 /分。结论 :CARTO标测有助于精确地定位不适当的窦性心动过速的消融靶点 ,减少射频消融的放电次数 ,提高成功率。     

Efficacy of Ivabradine in a Case of Inappropriate Sinus Tachycardia and Ventricular Dysfunction

Ivabradine in IST . We present a case of a 49‐year‐old man with inappropriate sinus tachycardia and ventricular dysfunction. The conventional treatment (ace‐inhibitor and beta‐blockers) was not well tolerated by the patient, so Ivabradine, a specific inhibitor of If current in the sinus node, was started. After 3 months of using this medication, we observed an improvement of ejection fraction and quality of life. (J Cardiovasc Electrophysiol, Vol. pp. 815‐817, July 2010)     

Changes in Autonomic Activity Preceding Onset of Nonsustained Ventricular Tachycardia

Background: The triggering role of the autonomic nervous system in the initiation of ventricular tachycardia has not been established. To investigate the relationship between changes in autonomic activity and the occurrence of nonsustained ventricular tachycardia (NSVT) we examined heart rate variability (HRV) during the 2-hour period preceding spontaneous episodes of NSVT. Twenty-four subjects were identified retrospectively as having had one episode of NSVT during 24-hour Holter ECG recording. Methods: We measured the mean interval between normal beats (meanRR), the standard deviation of the intervals between beats (SD), the percentage of counts of sequential intervals between normal beats with a change of >50 ms (%RR50), the logarithms of low- and high-frequency spectral components (InLF, InHF) of HRV for sequential 10-minute segments preceding NSVT. The correlation dimension (CDim) of HRV was calculated similarly for sequential 20-minute segments. We assessed the significance of the time-course change of each marker over the 120-minute period prior to NSVT onset. Results: MeanRR (P < 0.05), InLF (P < 0.0001), InHF (P < 0.0001), the natural logarithm of the ratio of LF to HF (ln[LF/HF]; P < 0.05), and CDim (P < 0.05) showed significant time-course changes during that period, while SD and %RR50 did not. MeanRR, InLF, InHF, and CDim all decreased prior to the onset of NSVT, whereas ln(LF/HF) increased. We divided the subjects into two groups: one consisting of 12 patients with coronary artery disease; and the second group of 12 patients without known coronary artery disease. Both groups showed significant changes (P < 0.05) of CDim, InLF, and InHF preceding the episodes of NSVT. Conclusions: Changes in the pattern of HRV prior to the onset of episodes of NSVT suggest that changes in autonomic activity may commonly play a role in the triggering of spontaneous episodes of NSVT in susceptible patients. The measured changes suggest a reduction in parasympathetic activity, perhaps in conjunction with an increase in sympathetic activity, may trigger NSVT.     

Cardiovascular Autonomic Dysfunction in Patients with Cancer

Purpose of Review

Elucidating the mechanisms that contribute to adverse cardiovascular (CV) outcomes and reduce quality of life among patients with cancer is paramount. Cancer, certain cancer drugs, radiation therapy, cancer-associated lifestyle disturbances, and cancer-independent comorbidities combine to predispose oncology patients to autonomic dysfunction (AD). This review will explore the assessment, etiology, and clinical implications of AD in cancer patients and will speculate on therapeutic and research opportunities.

Recent Findings

AD is particularly prevalent among patients with advanced cancer, but studies suggest increased prevalence across the entire continuum of cancer survivors compared to cancer-free controls. Data on cancer therapy-induced injury to the autonomic nervous system are limited to small studies. AD has been reported after cranial, neck, and mediastinal radiation therapy. Although AD has been shown to confer increased risk of adverse CV outcomes in cancer-free patients, the prognostic relevance of AD in oncology patients is less well investigated. Markers of AD including elevated resting heart rate (HR), reduced HR variability, and abnormal HR recovery have been associated with shorter survival times in various cancer cohorts. Furthermore, AD has been implicated in the etiology of cancer-related fatigue and exercise limitation.

Summary

Multiple risk factors predispose oncology patients to AD, which is associated with adverse outcomes, including increased mortality, exercise limitation, and fatigue among this cohort. The contribution of AD to overall morbidity and mortality in cancer survivors has largely been overlooked to date. Further investigation is necessary to better understand cancer-treatment specific autonomic injury and to evaluate the role of various pharmacological and non-pharmacological interventions with potential to tackle the sympathovagal imbalance observed in cancer survivors.