Saah electrocardiography: An insight toward microwaveform of atrioventricular node and His bundle potentials

ECG studies on the atrioventricular (AV) node and His bundle potential using surface electrodes are scarce. Although electrogram is a well-established technique for studying the AV node and His bundle potentials (1), it is not a routinely used method due to its invasive examination. Microelectrode techniques have also been utilized to ascertain the differential responses of the cells of the AV node and His bundle to various physiological and pharmacological interventions (2). The PR segment is usually a flat and isoelectric line and represents the duration of the conduction from the AV node to His bundle. Although abnormalities of the PR segment are not very common, they can indicate certain cardiac disease states. On the other hand, depression or reciprocal elevation of PR segment relative to the P-wave onset is often regarded as being due to the presence of atrial repolarization wave (3–6), pericarditis, or atrial infarction