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Mesor-hypertension: hints by chronobiologists
Insights
Circadian rhythms in cardiovascular parameters persist even with beta-blocker use. Continuous monitoring reveals that penbutolol does not eliminate these vital physiological variations, maintaining healthy blood pressure patterns.
Area of Science:
- Cardiology
- Chronobiology
- Physiology
Background:
- Circadian and ultradian rhythms are crucial in cardiovascular pathophysiology.
- Key cardiovascular parameters like heart rate and blood pressure exhibit daily patterns.
- Accurate blood pressure assessment requires prolonged monitoring, not single measurements.
Purpose of the Study:
- To investigate the effect of the beta-blocker penbutolol on circadian rhythms of cardiovascular parameters.
- To determine if penbutolol administration eliminates physiological circadian variations in blood pressure and heart rate.
- To assess the impact of penbutolol on cardiovascular rhythms using continuous monitoring.
Main Methods:
- Utilized automatic and continuous monitoring of cardiovascular parameters over extended periods (at least 48 hours).
- Analyzed circadian and ultradian rhythms in heart rate, arterial pressure, and other relevant metrics.
- Quantified cardiovascular parameter variations and identified potential phase shifts or amplitude changes.
Main Results:
- Penbutolol administration did not eliminate the physiological circadian variations in cardiovascular parameters.
- Continuous monitoring showed prominent amplitudes in cardiovascular rhythms during penbutolol treatment.
- A significant phase shift (approx. 100 degrees delay) in heart rate was observed in one patient.
Conclusions:
- The beta-blocker penbutolol preserves normal circadian variations in cardiovascular function.
- Continuous monitoring is essential for understanding the impact of medications on cardiovascular rhythms.
- Elimination of circadian rhythms is not observed with penbutolol, suggesting preserved physiological regulation.
Abstract:
Circadian systems are intermodulated by networks of specialized neural, hormonal and cellular functions, with time structures that are interdependent. In cardiovascular pathophysiology, circadian and ultradian rhythms of clinical interest have been demonstrated. Cardiac output, heart rate, arterial pressure and blood volume are the best known. Systolic and diastolic blood pressure and heart rate have circadian patterns in health and therefore arterial pressure cannot be evaluated by a single measurement during a 24-h span. With correct monitoring for at least 48-h it is possible to detect the mesor-hypertension and the possible amplitude-hypertension that precedes the mesor-hypertension. Prolonged elevation of blood pressure can cause irreparable harm to sensitive tissues. To quantify the damage, the concept of hyperbaric impact has been introduced. This is a measure of the excess load exerted upon the arterial walls. Studies of the beta-blocker penbutolol with correct automatic monitoring have shown the persistence of the physiological circadian variation in the cardiovascular parameters during penbutolol administration. The so-called elimination of the circadian rhythm in blood pressure, which would not really be desirable, was not seen in any of our patients, whose cardiovascular parameters were monitored continuously, day and night, while taking penbutolol. The amplitudes of the rhythms were always prominent. A phase shift, a delay of about 100 degrees, was demonstrated in the heart rate of one 63-year-old mesor-normotensive woman.