Frequency and Variability of Ventricular Premature Contractions—The Influence of Heart Rate and Circadian Rhythms

Abstract

STEINBACH, K. ET AL; Frequency and variability of ventricular premature contractions-the influence of heart rate and circadian rhythms. Present knowledge about arrhythmias is still too Jimited to prevent sudden cardiac death Long-term ambuJatory ECG monitoring should be the method of choice in further investigating and evaluating the possible relationships between the frequency of arrhythmias and heart rate [MR], circadian patterns, and effects of drugs Using a computer-supported, semiautomatic anaiysis system, 77 patients with a mean premature ventricuiar contraction fPVCJ-rate of over 1% were monitored for 24 hours (group A). Ten other patients with PVC's of over 1% were monitored for up to 96 hrs each, continuousiy, to demonstrate the reproducibility of possible circadian PVC's and HR patterns [group B] Another group of 44 patients (group C] underwent long-term ECG monitoring of 24 hrs before and during drug therapy with disopyramide (n = 15 pts, 200 mg t i d ], mexiJetine (n = 13 pts, 200 mg t.i d J, acebutoioJ (n = 9 pts, 200 mg b i d J and propafenon [n = 7 pts, 300 mg t i.d J to judge the drug effects in relation to their specific chronotropic properties. In group A patients there was a significant correlation (r = -0 602} between mean PVC frequency and respective PVC variabilities The latter increase with a reduction of the PVC rate and vice versa A circadian pattern of HR and PVC's can be demonstrated in the majority of group A and B patients. By using Scheffe's test to determine the required PVC reduction, the statistical PVC reduction curve lp<0 05} does not conform to the PVC-aboiition curve (PVCbeiowI%J in group B patients If patients without circadian PVC/HR patterns are under antiarrhythmic therapy, they need a much higher mean PVC-reduotion rate to reach the statistical significance level than patients without such a PVC and HR behavior. Drugs administered in Group C patients had different chronotropic effects Heart rate spectra were demonstrated for each antiarrhythmic drug used The distribution of arrhythmias, their variability, HR. circadian rhythm and the activity of antiarrhythmic drugs should be taken into account to narrow the gap between current antiarrhythmic treatment and the prevention of sudden cardiac death (PACE, Vol 5, January-February. 1982] antiarrhythmic therapy, circadian rhythm, premature ventricular contractions, longterm ambulatory ECG monitoring Since the establishment of Coronary Care recognize, qualify and treat arrhythmias before Units, the connection between sudden cardiac dangerous cardiac disturbances occur. The use death and life-threatening arrhythmias has been of new antiarrhythmic agents^-' and the applicawell known.'Today the physician's strategy is to • ,

Dependency of Premature Ventricular Contractions on Heart Rate and Circadian Rhythms during Childhood

“…That rhythm is similar to the rhythm which has been described previously in adult patients [1, 2, 3, 4, 5, 6, 7, 8]. The factors responsible for the circadian distribution of PVC remain speculative.…”

“…It has also been pointed out that heart rate itself, and more accurately the length of the cardiac cycle preceding the PVC, plays an important role in the genesis of some types of ventricular arrhythmias by enhancing certain electrogenic mechanisms. Rate dependence of PVC is a well-known phenomenon in adults [7, 8, 13]. It is characterized by the existence of a window of heart rate above and below which PVC disappear.…”

“…Studies in adults have described a circadian variation in ventricular arrhythmias [1, 2, 3, 4, 5, 6, 7, 8]and their dependency on heart rate [9, 10, 11]. However, no data are available in children.…”

Chronic Hemodialysis: High Risk Patients for Arrhythmias?

“…The PVC frequency in this patient group corresponds to that of healthy persons [12]. These results were clearly reprodu cible within two complete HD periods: the ECG moni toring duration of 96 h continuously did not only exclude the influence of the circadian variability but reduced also the influence of the spontaneous variability of infrequent arrhythmias [10,11], In contradiction to our findings, previously published studies [13][14][15][16] detected ventricular ectopics in nearly 100% of the patients -if any single PVC was taken into account and in 39-66% if complex ventricular arrhyth mias (L >11) were included (table IV). These obvious differences between the studies are difficult to explain particularly because of the lack of data (e.g.…”

“…The heart rate behavior did not deviate from well-known features [11]: It increased during HD in 13 patients ( fig. 3).…”