The effects of intravenous mexiletine on spectra of the signal-averaged ECG.
This study examined the effects of intravenous mexiletine on the time-domain and spectrotemporal signal-averaged ECG (SAECG). SAECGs were recorded in 60 postmyocardial infarction (MI) patients with more than 100 premature ventricular beats per hour, before and after a constant infusion of mexiletine, 7 mg/kg, given over 1 hour. Spectrotemporal analysis was done on a fixed analyzed signal duration of QRS complex and ST segment of X, Y, and Z leads using a temporal window of rectangular type, measuring the signal content between 10-120 Hz. Intravenous mexiletine produced no significant change in the mean values of any of the time-domain variables. However, mexiletine either increased or decreased the power density spectrum (PDS) and PDS ratio (40-120 Hz/25-120 Hz) of the SAECG, and in rare cases only did it not alter the spectra of the SAECG. When PDS ratio in lead Z decreased after mexiletine, it was usually higher at baseline in comparison with that when the PDS ratio increased, or vice versa. When the treatment with mexiletine was effective, PDS increased in comparison with that when the drug was ineffective, or vice versa. Not all ranges (10-120 Hz) of spectra of the SAECG, but only certain frequency bands (25-40 Hz in lead Z, P = 0.0253; 40-55 Hz in lead Y, P = 0.0096; 55-70 Hz in X lead, P = 0.0018; and in lead Z, P = 0.0002; 70-85 Hz in lead X, P = 0.0025; and in lead Z, P = 0.0075, 85-100 Hz in lead X, P = 0.0033) were associated with mexiletine efficacy.(ABSTRACT TRUNCATED AT 250 WORDS)
Zaliunas
R
R
Department of Cardiology, Kaunas Medical Academy, Lithuania.
Zabiela
P
P
Slapikas
R
R
Vainoras
A
A
Pentiokiniene
D
D
Levisauskiene
R
R
Bechtold
H
H
Meyer
U
U
D004562:Electrocardiography / Q000187:drug effects*; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D008801:Mexiletine / Q000008:administration & dosage* / Q000627:therapeutic use; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy / Q000503:physiopathology*; D012815:Signal Processing, Computer-Assisted
D008801:Mexiletine