Thoracic Key

Ectopic Rhythms and Premature Depolarizations Ectopic depolarizations can arise from many areas of the heart, but the surface ECG is markedly limited in its ability to precisely define the origin…

Atrioventricular Conduction The usefulness of intracardiac recording and stimulation techniques in humans was first realized during its application to patients with disorders of atrioventricular (A-V) conduction. Electrophysiologic study allowed confirmation…

Miscellaneous Phenomena Related to Atrioventricular Conduction Concealed conduction, the gap phenomenon, and supernormality are physiologic events that may be considered to be variants of the normal response. These phenomena are…

Electrophysiologic Investigation: General Concepts The electrophysiologic study should consist of a systematic analysis of dysrhythmias by recording and measuring a variety of electrophysiologic events with the patient in the basal…

Sinus Node Function Disorders of sinus node function are an important cause of cardiac syncope. Approximately 50% of permanent pacemakers implanted at our own and other institutions are for the…

Electrophysiologic Investigation: Technical Aspects Personnel The most important aspects for the performance of safe and valuable electrophysiologic studies are the presence and participation of dedicated personnel. The minimum personnel requirements…