Reproducibility in circadian rhythm of ventricular premature complexes.

To evaluate the existence and reproducibility of a circadian rhythm of ventricular premature complexes (VPCs), 38 patients (mean age 57 +/- 17 years) with greater than or equal to VPCs/hour were studied with 24-hour electrocardiogram Holter monitoring. Nineteen patients had coronary artery disease and 19 had structurally normal hearts. A second Holter electrocardiogram was recorded in all patients from 2 to 47 days (mean 11) after the first. Chronobiologic analysis was made by single and mean cosinor methods. A significant and similar circadian rhythm of VPCs was found in the total sample both on the first (mesor 399, acrophase at 15:08, p less than 0.01) and the second day (mesor 306, acrophase at 14:47, p less than 0.05), with 2 main peaks, the first in the late morning and the second in the afternoon. However, only 18 patients (47%, group A) had a significant individual circadian rhythm of VPCs on both days, whereas 20 (53%, group B) did not have a significant rhythm in greater than or equal to 1 day. A high reproducibility of the circadian rhythm of VPCs was found in group A patients, with a difference of 2.1 +/- 1.8 hours between the acrophases of the 2 days, whereas the difference was 4.4 +/- 3.3 hours in group B patients (p less than 0.01). Among group A patients, 14 (78%) had a VPC rhythm with acrophase occurring during waking hours, whereas the acrophase of 4 (22%) occurred during the night. The reproducibility of the circadian rhythm of VPCs was not influenced by gender, presence of coronary disease, medical therapy, basal VPC number, or day-to-day variability of VPCs, although group A patients were older than group B patients (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Accuracy in clinical arrhythmia detection of a real-time Holter system (Oxford Medilog 4500).

The accuracy of a real-time analysis Holter system (Oxford Medilog 4500) in detecting ventricular and supraventricular arrhythmias was evaluated. Hand-counted data from randomly selected hours of 152 ECG monitorings of 152 patients were used as the control standard. Accuracy of the system was evaluated on 606 hours for premature ventricular complexes (PVC), PVC couplets and supraventricular extrasystoles (SVE), and on 1,789 hours for ventricular tachycardia (VT), accelerated idioventricular rhythm (AIVR), and supraventricular tachycardia (SVT). Sensitivity and positive predictive accuracy for the Oxford system were (1) 92.9% and 94.9% for PVC; (2) 90.1% and 87.8% for PVC couplets; (3) 98.1% and 56% for AIVR; (4) 80% and 82.3% for VT; (5) 88.6% and 56.5% for SVE, and (6) 43.7% and 60.2% for SVT. Furthermore, negative predictive accuracy, the ability to predict the total absence of an arrhythmic event in an hour, was determined. It was 91.7% for PVC, 99.5% for PVC couplets, 99.9% for AIVR, 99.7% for VT, 95% for SVE, and 98% for SVT. ventricular arrhythmias, whereas significant inaccuracies appear to exist in the analysis of supraventricular arrhythmias.

[Characteristics of non-sustained ventricular tachycardia found during dynamic ECG in patients with recent myocardial infarction]. / Caratteristiche delle tachicardie ventricolari non sostenute riscontrate all'ECG dinamico in pazienti con infarto miocardico recente.

The characteristics of ventricular tachycardia found during Holter ECG monitoring before discharge in patients hospitalized because of acute myocardial infarction were analyzed. One or more ventricular tachycardia episodes were found in 29 of 251 patients (11.5%). On the whole, there were 233 episodes of ventricular tachycardia: 18 patients (62%) had only one episode of ventricular tachycardia, 9 (31%) 2-5 episodes and 2, respectively, 68 and 118 episodes. Episodes of ventricular tachycardia were more numerous in patients with frequent or polymorphic premature ventricular complexes than in patients with sporadic or monomorphic premature ventricular complexes. Fifty-seven ventricular tachycardia episodes were analyzed: 30 of 3 beats, 25 of 4-9 beats and 2 of 15 beats. Forty-seven episodes were monomorphic and 10 (17.5%) were polymorphic. The ventricular tachycardia rate was 136.4 +/- 25 b/m' (range 104-200). The RR'/QT ratio (where RR' = coupling interval of the first beat of ventricular tachycardia) was 1.67 +/- 0.42 and was not correlated either with the rate or the number of beats of ventricular tachycardia. Heart rate at the moment of ventricular tachycardia was 82 +/- 15 b/m' and QT interval 0.36 +/- 0.05 sec; there was no difference when compared to their values of 1 and 5 minutes before ventricular tachycardia. Furthermore, the heart rate showed no difference when compared to the mean value of the hours in which ventricular tachycardia episodes occurred. In addition, heart rate was not correlated with ventricular tachycardia rate, whereas a good correlation was found between the last RR interval preceding ventricular tachycardia and RR' interval (r = 0.61, P less than 0.01).

Circadian variation of ventricular tachycardia in acute myocardial infarction.

Circadian rhythms have been described both for acute myocardial infarction (AMI) and sudden death. In this study the diurnal distribution of ventricular tachycardia (VT) in patients with AMI was analyzed. Ninety-four AMI patients with greater than or equal to 1 VT on Holter electrocardiographic monitoring who were not taking antiarrhythmic drugs were studied. Forty-seven patients had a recent AMI (group A) and 47 an old AMI (group B). Chronobiologic analysis was made by single cosinor method. There were 157 VTs (mean 1.67 VTs/patient, range 1 to 10) in the 94 patients: 70 in group A and 87 in group B. A significant circadian rhythm of VT was found in the total population with acrophase at 2:29 P.M. The hourly distribution of VT showed a tendency to bimodality, which seemed due to a different time of peak VT occurrence in group A (significant rhythm with acrophase at 4:40 P.M.) and group B (significant rhythm with acrophase at 12:39 P.M.). Thus, the hourly VT frequency in patients with AMI has a significant circadian variation with the highest occurrence in the awake hours, similar to the rhythms described for AMI and sudden death.