Case summary A 49-year-old man experienced syncope while he crossed a street, and he was transferred to our hospital. An electrocardiogram (ECG) showed a second-degree 2:1 atrioventricular block with narrow QRS complexes (Figure 1A). Curiously, the RR intervals were not constant while the PP intervals remained steady during the 2:1 AV block (Figure 1B). The echocardiogram revealed a normal left...

Concealed (C) His bundle ectopic systoles (H') have been shown in man to give rise to first and second degree atrioventricular (A-V) block and to simulate nonconducted atrial premature beats (P'). This report outlines a hitherto undescribed electrophysiologic consequence of H' in a 69-year-old man with arteriosclerotic heart disease and a Wenckebach type second degree A-V block in the His-Purki...

The induction of ventricular tachycardia by ventricular stimulation was investigated in 46 patients with isolated Wolff-Parkinson-White syndrome (10 concealed) and 36 control patients with normal electrocardiograms and conduction systems. None of those studied had spontaneous ventricular arrhythmias or myocardial or valve disease. Single and double ventricular extrastimuli were delivered at 3 c...

AIMS The concealed phase of arrhythmogenic right ventricular cardiomyopathy (ARVC) may initially manifest electrophysiologically. No studies have examined dynamic conduction/repolarization kinetics to distinguish benign right ventricular outflow tract ectopy (RVOT ectopy) from ARVC's early phase. We investigated dynamic endocardial electrophysiological changes that differentiate early ARVC dise...

A 45-year-old woman diagnosed with Wolff-Parkinson-White syndrome preferred treatment with propafenone rather than catheter ablation. A 12-lead electrocardiogram (Fig. 1) after the drug administration showed sinus arrhythmia; alternating ventricular preexcitation; and alternating T wave inversion in the inferior leads during normal AV conduction. Ventricular preexcitation may disappear because ...

OBJECTIVE The aim of the present study was to assess the prevalence of subtle morphologic substrates, clinically unrecognizable, underlying sudden cardiac death (SCD) in young people with apparently normal heart. METHODS In the time interval 1979--1998, 273 consecutive cases of SCD in young people (< or =35 years) which occurred in the Veneto Region of Italy were prospectively studied. Follow...

The presence of a single atrioventricular (AV) node and accessory pathway associated with tachycardia is common. However, tachycardia with alternating QRS morphology and cycle length is uncommon, and may indicate the presence of a double loop. We reported the case of a 45-year-old man with tachycardia and continually alternating QRS morphology and cycle length. The man with intermittent palpita...

Catheter ablation of 215 accessory pathways (APs) using radiofrequency current (RF) was attempted in 204 consecutive patients. Two hundred twelve of the 215 (99%) APs were successfully ablated. After a minimum of follow-up period of 1 month (mean 8.5 +/- 5.4 months), AP conduction had returned in 17 patients (8%). Recurrence of AP conduction was manifest by atrioventricular (AV) reentrant tachy...

Paroxysmal atrioventricular (AV) block is an unusual phenomenon that has been previously described. We report the case of a 78-year-old man who presented after an episode of syncope while seated in church. On presentation to the hospital, the initial electrocardiogram showed sinus rhythm with a normal PR interval, QRS duration, and corrected QT interval. During telemetry monitoring, several epi...