Bursts of ventricular pacing at cycle lengths of 350-260 ms were introduced during atrial fibrillation in nine patients, and the post-pacing R-R intervals were compared to the R-R intervals of spontaneous QRS complexes. In eight of nine patients, the mean post-pacing R-R interval was 126-199 ms longer than the mean spontaneous R-R interval (p less than 0.005). Spontaneous runs of aberrantly con...

BACKGROUND Syncope in patients with supraventricular tachycardia has been suggested to be an ominous finding, predictive of rapid rates during tachycardia. METHODS AND RESULTS To explore the mechanism of syncope during supraventricular tachycardia, tachycardia was induced in the supine position and after passive head-up tilting to 60 degrees in 13 patients with atrioventricular (AV) node reen...

Arrhythmias in children are the enemy of any medical emergency. Different mechanisms should be very dangerous in particular for its adaptation mechanisms. Tachyarrhythmias (extrasistols, supraventricular tachycardia SVT, permanent junctional reciprocating tachycardia, atrial flutter, supraventricular tachycardias, ventricular tachycardias). Bradyarrhythmias (atrioventricular blocks) and channel...

Major spontaneous variation in cycle length during supraventricular tachycardia is quite an uncommon phenomenon, which sometimes can mislead a correct diagnosis. We describe a patient who developed spontaneous variation in cycle length during electrophysiologic study in whom the coronary sinus cannulation was extremely difficult. In this situation, careful inspection of the mechanisms associate...

A41-year-old man was referred for electrophysiological evaluation after recurrent syncope that occurred frequently during vigorous exercise. The patient had a complete, normal cardiological work up, including a resting ECG, an exercise stress test, and an echocardiogram. He reported that just before loss of consciousness, his heart was beating very fast. An electrophysiological study was perfor...

BACKGROUND Dermatomyositis is an idiopathic inflammatory myopathy, often associated with an underlying malignancy. Its prevalence rate is approximately one per 100,000 in the general population, and is even rarer without evidence of a cancer. Dermatomyositis rarely involves myocardial muscle fibers, but has shown to be associated with cardiac arrhythmias. CASE PRESENTATION We present a case o...