Hypertensive patients with coronary artery disease and an abnormal pattern of heart rate variability

Heart rate variability (HRV) was investigated in 17 normotensive (N) and 8 hypertensive (H) patients with stable CAD and good ventricular function. Recordings were made on the evening before and after induction of anesthesia for CABG surgery each in supine and repeated in head-up tilt position. HRV was determined by autoregressive analysis as total (TO) and high frequency power in absolute (HF) and in relative units (PA), representing vagal activity. While in both groups anesthesia induces a marked decrease in TO and HF (p<0.01), PA, initially higher in group N (n.s), increases (p<0.01). The reaction to tilting was significantly different (p<0.01) in the awake patients, with N showing a decrease in vagal influence, compared to a paradoxical increase in H. This reaction is attenuated but similar under anesthesia, possibly explaining frequent blood pressure instabilities in H by impaired autonomic regulation.<>