Open AccessThe acute electrophysiological effects of intravenous metoprolol
Author(s) -
Camm A. J.,
Whitmarsh V. B.,
Ward D. E.
Publication year - 1982
Publication title -
clinical cardiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.263
H-Index - 72
eISSN - 1932-8737
pISSN - 0160-9289
DOI - 10.1002/clc.4960050503
Subject(s) - medicine , metoprolol , refractory period , palpitations , electrophysiology , cardiology , anesthesia , atrioventricular node , intracardiac injection , tachycardia
Summary: The cardiac electrophysiological effects of metoprolol were studied in ten patients (pts) aged 22–51 years undergoing intracardiac stimulation studies for paroxysmal palpitations. The following measurements were made: (1) basic sinus cycle length (SCL); (2) sinus node recovery time (SRT) following overdrive pacing; (3) atrio‐His (A‐H) and His‐ventricular (H‐V) conduction intervals during regular atrial pacing; (4) effective refractory periods of the atria (AERP), A‐V node (AVERP) and ventricular myocardium (VERP); and (5) A‐V nodal functional refractory period (AVFRP). All measurements were repeated 10–20 min after a slow bolus intravenous injection of metoprolol (0.2 mg/kg body weight). Results were analyzed by the Wilcoxon Signed Rank test. Highly significant increases in: SRT (932±166 to 1107±225 ms, p<0.001) and A‐H (72±14 to 103± 14 ms, p<0.001) were observed. There were also small increases of lesser significance in SCL (794± 160 to 898±190 ms, p<0.01), AVERP (308±46 to 341±66 ms, p<0.02), and AVFRP (376±43 to 416±59 ms, p<0.01). Metoprolol did not affect the H‐V interval, the AERP, or the VERP. These results are similar to those of other beta blockers.