Near doubling of heart rate after intravenous verapamil for treatment of atrial fibrillation without preexcitation.

Initial treatment of atrial fibrillation often involves pharmacological therapy to control ventricular response. While verapamil is usually safe and effective when used for this purpose, we report a proarrhythmic response. In this report a 30-year-old female presented with palpitations associated with atrial fibrillation and a ventricular response of 145 beats/min. Soon after she was given 5 mg of intravenous verapamil her ECG documented a regular wide QRS tachycardia at 290 beats/min. After 7 seconds the rhythm returned to an irregularly irregular narrow QRS tachycardia at 125-150 beats/min. At a later electrophysiology study there was neither evidence of preexcitation nor inducible supraventricular or ventricular tachycardia. These data suggest that verapamil may have been associated with acceleration of the heart rate. The mechanism of proarrhythmia may be related to an alteration in the atrial rhythm from atrial fibrillation to atrial flutter, with additional factors as well.

Clinical assessment of adrenergic tone and responsiveness to beta-blocker therapy in patients with symptomatic ventricular tachycardia and no apparent structural heart disease.

To further define the relation between changing adrenergic tone, beta-blocker therapy, and clinical ventricular tachycardia (VT), we evaluated these factors in 35 patients with VT unrelated to coronary artery disease or ventricular dysfunction. Testing included Holter monitoring (91% had VT), exercise test (69% had VT), Adrenergic responsiveness of VT was graded according to diurnal variation, response to exercise, isoproterenol infusion, and response to beta-blockers. beta-Blockers were effective and well tolerated in this population. There was also a predictable relation between changing adrenergic tone and the arrhythmia response to beta-blocker therapy.

Is the time domain signal-averaged electrocardiogram helpful in patients with ventricular tachycardia without apparent structural heart disease?

The signal-average electrocardiogram (SAECG) has been a screening method for identifying patients at risk for ventricular tachycardia (VT) in the setting of coronary artery disease (CAD). Its significance in patients with VT unrelated to CAD or left ventricular dysfunction is undetermined. In order to define the value of SAECG in this patient population further, we compared the time domain SAECG at 25, 40, and 80 Hz filters in 35 patients with clinically symptomatic VT in the absence of structural heart disease was compared with 10 normal controls and 10 patients with CAD and inducible VT. SAECG data in patients without structural heart disease were intermediate between normal controls and patients with CAD. No single or combined SAECG criterion helped to differentiate between patients with inducible and noninducible VT. There was no concordance to other arrhythmia testing. It was concluded that signal-averaged electrocardiography may have little screening value in VT unrelated to CAD or left ventricular dysfunction.

Spectrum of right heart involvement in patients with ventricular tachycardia unrelated to coronary artery disease or left ventricular dysfunction.

We studied 41 patients with clinically symptomatic ventricular tachycardia in the absence of coronary artery disease or left ventricular dysfunction to define the extent of right and left heart derangement and their relation to electrophysiologic and clinical data. Individual echocardiographic measurements as well as global assessment scores of the right and left heart demonstrated a wide spectrum of right heart echocardiographic abnormalities. There was much less variation in the left heart, with the majority of patients being close to normal. There was an association between the right heart score, the clinical presentation of arrhythmia, the response to programmed electrical stimulation, and the recurrence of arrhythmia (p < 0.05). Thus echocardiographic findings demonstrate the whole spectrum of right heart involvement in patients with apparent idiopathic ventricular tachycardia and can give insight into clinical history, arrhythmia inducibility, and prognosis.