Increased heterogenity of ventricular repolarization in obese nonhypertensive children.

OBJECTIVE: Obese children, without arterial hypertension, may be a unique clinical opportunity to evaluate the effect of obesity, per se, on ventricular repolarization, excluding the influence of possible comorbidities. The QTc dispersion (QTc-d), JTc dispersion (JTc-d), and transmural dispersion of repolarization (TDR) have been suggested to be electrocardiographic indexes reflecting the physiological variability of regional ventricular repolarization. The aim of our study is to define the effects of obesity on the ventricular repolarization in obese children who have no other clinically appreciable cause of heart disease. METHODS: The study involved 70 subjects (48 male, 22 female), with a mean age (± standard deviation) of 13 ± 2 years. A total of 35 individuals were obese (Group A: 24 male, 11 female, mean body mass index [BMI] of 38.2 ± 5.8 kg/m(2) ), and 35 participants were healthy lean children (Group C: 24 male, 11 female, mean BMI of 22.3 ± 0.3 kg/m(2) ). Heart rate; QRS duration; maximum and minimum QT interval; and QTc-d, JTc-d, and TDR measurement were performed. RESULTS: Compared with the healthy control group, obese children presented increased values of the QTc-d, JTc-d, and TDR (31.1 ± 10.6 vs 46.2 ± 15.3 ms, P < 0.003; 29.8 ± 8.5 vs 40.1 ± 10.3 ms, P < 0.04; 83.2 ± 13.5 vs 100.7 ± 16.3 ms, P < 0.05). A statistically significant correlation was found between the values of QTc-d, insulin serum concentration (r = 0.46, P = 0.04), and homeostasis model assessment of insulin resistance (r = 0.34, P = 0.03). CONCLUSIONS: Our data suggest that obese nonhypertensive children have an increased ventricular repolarization heterogeneity in relation to controls.

Superselective cannulation of coronary sinus branch with telescopic system during left ventricular lead placement.

We present a case of a 55-year-old man with idiopathic dilated cardiomyopathy, ejection fraction (EF) of 27%, left bundle branch block with QRS duration of 160 ms, NYHA class III, and optimal medical therapy for at least 6 months who was referred to our division for cardiac resynchronization therapy (CRT) using a biventricular pacing device. During the operation, the coronary sinus branch cannulation failed using classical angioplasty guide wire techniques. The pacing lead was successfully implanted into the posterior target vein using a telescopic dual-catheter system.

Severe obesity and P-wave dispersion: the effect of surgically induced weight loss.

BACKGROUND: Recent data have shown that obesity is an important potential risk factor for atrial fibrillation (AF). The mechanism of development of AF in obesity patients is still unclear and may be related to atrial refractoriness heterogeneity. The aim of our study was to determine the influence of bariatric surgery with a consequent substantial weight loss on P-wave dispersion in morbidly obese population. METHODS: We enrolled in this study 40 severe obese patients, and 40 age-matched non-obese healthy subjects were also recruited as controls. All subjects underwent conventional 12-lead electrocardiography for the analysis of P-wave dispersion. All subjects underwent bariatric surgery and were resubmitted to electrocardiography, biochemical, and anthropometric examination within 12 months after intervention. RESULTS: Severe obese patients had greater values in P-wave duration and dispersion than the normal weight controls. Bariatric surgery reduced significantly P-wave dispersion. There was a significant correlation between decrease of atrial refractoriness heterogeneity and bariatric-surgery-induced weight loss. CONCLUSIONS: In severe obese patients, surgically induced weight loss reduction is associated with significant decreased in P-wave dispersion. The reduction of the atrial refractoriness heterogeneity may be of clinical significance by reducing the risk of atrial fibrillation in morbidly obese subjects.

Sympathovagal balance analysis in idiopathic postural orthostatic tachycardia syndrome.

The idiopathic postural tachycardia syndrome (POTS) is a complex disorder characterized by chronic orthostatic symptoms and an increase in heart rate within 10 minutes of standing on upright posture, without significant orthostatic hypotension. We describe a case of a 36 year-old patient with POTS, diagnosed by head-up tilt testing. Power spectral analysis of heart rate variability (HRV), performed during the tilt test, revealed the ratio of low and high frequency powers (LF/HF) that increased with the onset of orthostatic intolerance. The increase in LF/HF power ratio may represent sympathetic beta-receptors hyperactivity. Atenolol alleviated his clinical symptoms.

Effect of weight loss following bariatric surgery on myocardial dispersion of repolarization in morbidly obese patients.

BACKGROUND: Weight-stable obese subjects have an increased risk of arrhythmias and sudden death, even in the absence of cardiac dysfunction, and the risk of sudden cardiac death (SCD) with increasing weight is seen in both genders. The mechanism of unexplained deaths in obese patients is still unclear and may be related to ventricular repolarization abnormalities. The aim of this study is to determine the effect of severe obesity on spatial and transmural ventricular repolarization and to clarify the influence of bariatric surgery with a consequent substantial weight loss on arrhythmogenic substrate in the morbidly obese population. METHODS: For the study, we enrolled 100 severely obese patients; 50 age-matched non-obese healthy subjects were also recruited as controls. All subjects underwent conventional 12-lead electrocardiography for analysis of spatial and transmural ventricular repolarization assessed by corrected QT dispersion (QTc-d), corrected JT dispersion (JTc-d) and transmural dispersion of repolarization, (TDR). All subjects underwent bariatric surgery and were resubmitted to electrocardiographic, biochemical and anthropometric examination 12 months postoperatively. RESULTS: Severely obese patients had greater values in QTc-d, JTc-d and TDR than the normal-weight controls. Bariatric surgery reduced significantly the QTc-d value, JTc-d value and TDR value. There was a significant correlation between decrease of heterogeneity of repolarization indexes (QTd, JTd and TDR) and bariatric surgery-induced weight loss. CONCLUSIONS: In severely obese patients, surgically-induced weight loss is associated with significant decrease in the heterogeneity of ventricular repolarization. The reduction of spatial (QTc-d, JTc-d) and transmural dispersion of repolarization (TDR) may be of clinical significance, by reducing the risk of potentially fatal arrhythmias in morbidly obese subjects.

Coronary sinus spasm during left ventricular lead implantation for biventricular pacing.

The authors present a case of coronary sinus spasm during left ventricular lead implantation for biventricular pacing relieved by direct infusion of nitroglycerin.

Heart rate variability analysis in postural orthostatic tachycardia syndrome: a case report.

The authors present a case of 36 year old male patient with idiopathic postural orthostatic tachycardia syndrome (POTS) diagnosed during head-up tilt testing. Power spectral analysis of heart rate variability (HRV) during the tilt test revealed that the ratio of low and high frequency powers (LF/HF) increased with the onset of orthostatic intolerance. This analysis confirmed in our patient a strong activation in sympathetic tone.