Five cases of atrial ectopic activity associated with sinus bradyeardia are reported. The ectopic activity was abolished in all cases when the sinus rate was increased spontaneously or by atropine. The report demonstrated that the incidence of ectopic activity increases in the atrium at the slower basic rates as it does in the ventricle. It was emphasized that atrial ectopic activity associated...

Automaticity (postpacing impulse recovery time) of the sinus node or subsidiary pacemakers (or both) was determined by intracardiac recordings and atrial overdrive pacing in three patients with disease of the sinus node. Their electrocardiographic manifestations included sinus bradycardia, sinoatrial block, sinus arrest, afrioventricular junctional rhythm, and atrioventricular dissociation. One...

Two patients with mild aortic insufficiency inhaled amyl nitrite during routine echocardiographic examinations. One developed sinus arrest and syncope and the other had pronounced sinus bradycardia. The mechanism of this paradoxical response is unclear. Caution should be exercised when amyl nitrite is administered for diagnostic purposes.

We describe the successful endovascular repair of an intracranial aneurysm causing subarachnoid hemorrhage in a 62-year-old man, who was initially diagnosed and treated as a case of symptomatic sinus bradycardia. The aim of this report and following discussion is to discuss the subtle warning signs of intracranial aneurysm that may masquerade as sinus node dysfunction.

We found that sinus bradycardia in members of a large family was associated with a mutation in the gene coding for the pacemaker HCN4 ion channel. Pacemaker channels of the sinoatrial node generate spontaneous activity and mediate cyclic AMP (cAMP)-dependent autonomic modulation of the heart rate. The mutation associated with bradycardia is located near the cAMP-binding site; functional analysi...

OBJECTIVES We hypothesized that neonatal long QT syndrome (LQTS) with 2:1 atrioventricular block (AVB) could be related to HERG mutations. BACKGROUND Early onset of LQTS is rare but carries a high risk of life-threatening events such as ventricular arrhythmias and conduction disorders. There are no data on possible gene specificity. METHODS We analyzed the characteristics and outcomes of 23 neo...

Bradycardia is common in critical care units. It may be transient, asymptomatic and of little consequence, or life-threatening. Bradycardia may result from abnormalities of the sinus node, atrioventricular node, or the His-Purkinje system. It may also be precipitated by drug effects or enhanced vagal tone. Proper diagnosis is pivotal to determining prognosis and management. Temporary and perman...

安孫子 保 The work was supported by a grant from the Ministry of Education in Japan. In spite of numerous reports on bradycardia produced by cardiac glycosides hitherto , the mechanism is not completely clarified. Ackermann (1) reported that early digitalis bradycardia was prevented by vagal severance or by administration of atropine. This observation has generally been ac cepted. Heymans and Heyma...

A patient with a sinus bradycardia and angina is described who was unable to increase his heart rate on vigorous exercise by more than a few beats. His severe angina was attributed to the bradycardia. Atrial pacing of his heart abolished his angina and increased his exercise tolerance. Circulatory changes at rest, on exertion, and with atrial pacing are described. The cause of angina in this pa...