Csaba Kun

The effect of sleep apnea on QT interval, QT dispersion, and arrhythmias.

QT interval (QT) and QT dispersion (QTd) are electrocardiograph (ECG) parameters for the evaluation of myocardial repolarization. The inhomogeneity of ventricular repolarization is associated with ventricular arrhythmias. An increased QT, QTd, and increased incidence of nocturnal cardiac rhythm disturbances have been described in patients with obstructive sleep apnea (OSA), while other investigators did not find a relationship between ventricular arrhythmias and OSA.

Adenosine-Dependent Concealed Accessory Pathway

Adenosine is routinely used during ventricular pacing to exclude the persistence of retrograde accessory pathways conduction after radiofrequency (RF) ablation procedures by blocking conduction over the atrioventricular node. This is the first report of an adenosine‐dependent concealed accessory pathway demonstrating transient conduction only after adenosine administration. Our findings may have potential clinical implications in reducing recurrence after accessory pathway ablation. Furthermore, it may add relevant information regarding the ability of adenosine to elicit dormant conduction after RF ablation, a phenomenon that has acquired considerable interest in the era of pulmonary vein isolation. PACE 2012; 35:e91–e93)

Long-term arrhythmia variability after monomorphic ventricular tachycardia in patients with an implantable cardioverter defibrillator.

Background:  Arrhythmia burden in patients receiving an implantable cardioverter defibrillator (ICD) after monomorphic ventricular tachycardia (mVT) is higher than in patients with other indications. We investigated the long‐term arrhythmia profile in this subset of patients.

Cryoballon isolation of the pulmonary veins in atrial fibrillation: Mid-term results after the first 55 patients

UNLABELLED Several transcatheter techniques based on radiofrequency energy were elaborated for the treatment of atrial fibrillation through the last decade. Recently, similar success rates with a better safety profile concerning life threatening complications were reported with the novel methode of cryoballon isolation of the pulmonary veins. This paper summarizes our initial experience with cryoballon ablation after the first 55 patients. METHOD [corrected] Symptomatic patients refractory to aniarrhythmic medication mostly with paroxysmal atrial fibrillation without significant structural heart disease were enrolled. Cannulation and isolation of all pulmonary veins were attempted using a 28 mm double-wall cryoballon inflated at the ostium of the vein and abolishing eletrical activity of atrial tissue around its perimeter by freezing to -70 C. Intravenous heparin during and oral anticoagulant after the procedure was administered. Conventional ECGs, Holter ECGs and transtelephonic ECG recordings were used through 6 months follow-up for rhythm monitoring. RESULTS In 55 patients enrolled (18 female; age: 56 + or - 33,64 years) 165 out ot 192 (86%) pulmonary veins were successfully isolated. All pulmonary veins were isolated in 37 patients (67%). Procedure time was 155.67 + or - 100.66 min, while fluoroscopy time was 34.04 + or - 31.89 min. In 34 patients with 6 months follow-up 24 (70%) either remained free of arrhythmia (17 patients) or had a significant decrease in arrhythmia burden (7 patients). CONCLUSION Based on our initial experience, cryoballon isolation of pulmonary veins appears to be a more simple procedure with similar efficacy to radiofrequency ablation in the treatment of atrial fibrillation.

Arrhythmias in patients with obstructive sleep apnea

The authors summarize the current knowledge on the types, prevalence, reasons, diagnosis and current therapy of arrhythmias occurring in patients with obstructive sleep apnea. Most of the patients with obstructive sleep apnea have nocturnal bradycardia (5-50%), paroxysmal tachyarrhythmia (atrial 35%; ventricular 0-15%), or both. The frequency of rhythm disturbances associated with the severity of the sleeping disorder. It is important to recognize the factors predisposing to arrhythmias and the early appropriate therapy of patients is essential, in order to protect patients from life threatening arrhythmias which may worsen the clinical outcome.