UNLABELLED We reported a 60-year-old male patient who had a paroxysmal supraventricular tachycardia with QRS duration alternans (alternation between narrow QRS and wide QRS beats) and electrical alternans, but without any cycle length alternans. In the laboratory, slow-fast atrioventricular nodal reentrant tachycardia was easily induced by an atrial extrastimulus, and the arterial pressure reco...

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...

CONTEXT A shortening of the atrial refractory period has been considered as the main mechanism for the increased risk of atrial fibrillation in hyperthyroidism. However, other important factors may be involved. OBJECTIVE Our objective was to determine the activity of abnormal supraventricular electrical depolarizations in response to elevated thyroid hormones in patients without structural he...

Electrophysiological effects of 2 to 2.5 mg/kg iv disopyramide were studied in 10 patients with dual nodal pathways who used a slow pathway for anterograde and a fast pathway for retrograde conduction during paroxysmal supraventricular tachycardia (mean cycle length 308.5 +/- 37 ms; range 260-370 ms). Disopyramide terminated the tachycardia in six cases by production of ventriculoatrial block i...