Related Experiment Videos
A chronobiologic study on some cardiovascular parameters
Insights
This study reveals circadian rhythms in heart rate, QT interval, and wave voltages. It also found rhythms in arrhythmias and blood pressure, suggesting potential for optimized drug timing.
Area of Science:
- Cardiovascular Physiology
- Chronobiology
- Internal Medicine
Background:
- Understanding the daily biological rhythms (circadian) of cardiovascular parameters is crucial for managing conditions like hypertension and coronary artery disease.
- Previous research has indicated potential chronobiological patterns in cardiac function, but comprehensive studies across various cardiovascular metrics and subject groups are limited.
Purpose of the Study:
- To investigate the chronobiologic patterns of heart rate, electrocardiogram (ECG) parameters (R and T wave voltage, QT interval, ST segment displacement), premature heartbeats, and arterial blood pressure in a diverse group of untreated individuals.
- To explore potential influences of lifestyle factors like smoking and sleeping on these rhythms.
- To compare chronobiologic patterns between healthy individuals and those with cardiovascular risk factors or disease.
Main Methods:
- Dynamic electrocardiography and autometric arterial blood pressure measurements were employed in 131 untreated subjects.
- Subjects included individuals with hypertension, coronary artery disease risk factors, diagnosed coronary artery disease, healthy controls, and shift workers.
- Statistical analysis was used to identify circadian, ultradian, and circaseptan rhythms and assess the influence of smoking and sleep.
Main Results:
- Circadian rhythms were confirmed for heart rate, QT interval duration, and R and T wave voltages.
- Circadian and ultradian rhythms were observed in premature atrial and ventricular beats.
- Circadian and circaseptan rhythms were identified in arterial blood pressure.
- Smoking appeared to influence the timing (acrophase) of R wave voltage rhythm, while sleep showed a relationship with ST segment displacement but not R and T wave voltages.
- Minimal differences in chronobiologic patterns were noted between coronary artery disease patients and healthy subjects, contrasting with some prior findings.
Conclusions:
- The study confirms the presence of significant circadian and other biological rhythms in various cardiovascular parameters and arrhythmias.
- Findings suggest that lifestyle factors like smoking may modulate these rhythms.
- While differences between patient groups were subtle, the identified rhythms highlight the potential for chronotherapy in managing cardiovascular conditions, warranting further investigation for optimized drug administration timing.
Abstract:
We studied the chronobiologic pattern of heart rate, R and T wave voltage, QT interval, and ST segment displacement. Premature atrial and ventricular beats obtained by dynamic electrocardiography, as well as arterial blood pressure measurements obtained by autometry, have also been studied in 131 untreated subjects (25 with hypertension, 28 with major risk factors for coronary artery disease, 9 with coronary artery disease, 37 presumably healthy and 11 shift workers). Our results show the existence of circadian rhythms in heart rate, in the duration of the QT interval and also in the voltage of R and T waves. Our data for R and T wave voltages do not completely agree with those from other authors. We demonstrated also that smoking may influence the circadian acrophase of the rhythm in R wave voltage while sleeping does not show any relationship with R and T wave voltages although it seems related to the displacement of the ST segment. We could point out only small differences in the chronobiologic behavior of patients with coronary disease and that of normal subjects, unlike the results previously reported by other authors. Our study demonstrated the existence of circadian and ultradian rhythms in premature atrial and ventricular beats as well as circadian and circaseptan rhythms in arterial blood pressure. Further studies are needed to improve our chronobiologic knowledge in order to optimize dosage and time of administration of the drugs used in the long term management of arrhythmias and hypertension.