[Recent progress in analysis of arrhythmias using electrocardiography].
Recently, various novel techniques have been used in clinic to analyze arrhythmias. These include vectorcardiography, body surface ECG mapping, signal-averaged ECG, intracardiac electrogram and monophasic action potentials, and 24-hour ECG recordings. We examined 24-hour ECG recordings in patients with frequent ventricular premature contractions (VPCs), to identify VPCs possibly due to delayed afterdepolarizations (DADs). We evaluated :1) the relationship between VPC frequency and heart rate (HR); 2) the time course of changes in VPC frequency following an abrupt and sustained increase in HR; and 3) the effects of oral diltiazem on VPCs. Patients could be divided into 2 groups according to whether VPCs increased with an increase in HRs (positive correlation or P group) or not (non-positive correlation or NP group). In the P group, changes in VPCs after an abrupt and sustained increase showed 2 types: 1) delayed-ascent type, in which VPCs increased as the duration of HR increase was prolonged; and 2) non-delayed-ascent type. Diltiazem suppressed almost only the VPCs of delayed-ascent type. The VPCs of delayed-ascent type had several important feature characteristic of DADs, suggesting these VPCs may be due to DADs.
Fujino
T
T
Department of Laboratory Medicine, Oita Medical University.
Ishida
S
S
Takahashi
N
N
Nakagawa
M
M
Ito
M
M
Saikawa
T
T
D001145:Arrhythmias, Cardiac / Q000175:diagnosis*; D005117:Cardiac Complexes, Premature / Q000175:diagnosis; D004562:Electrocardiography / Q000379:methods*; D015716:Electrocardiography, Ambulatory; D006801:Humans; D012815:Signal Processing, Computer-Assisted