[Relations between stress in daily life and hypertensive cardiovascular accidents].

Hypertensive patients with cardiovascular disorders can encounter dangerous stress even during ordinary daily activities. Numerous cardiovascular accidents(ischemic heart attacks and strokes) occur during the morning hours, which are, therefore, from this perspective, the most dangerous part of the 24-hour day. During the morning, both blood pressure and heart rate rise suddenly. Total peripheral resistance(TPR) also increases, whereas baroreceptor sensitivity(BRS) decreases in patients with essential hypertension. The following haemodynamics factors may contribute to these phenomena. During sleep, no food or drink is ingested; consequently, plasma volume decreases(hematocrit therefore increases), and the autonomic nervous system becomes unbalanced(the LF/HF ratio in heart rate variability increases); and BI[= Pd x RR/ (Pd0 x RR0)-1] decreases (Pd = diastolic blood pressure, RR = pulse interval, Pd0 = base Pd during sleeping hours, RR0 = base RR during sleeping hours) in the morning. These haemodynamics changes during the morning hours may diminish coronary blood flow.