ABSTRACT
OBJECTIVE: Congestive heart failure (CHF) is characterized by sympathetic overactivity but reduced variability of heart interval and sympathetic nerve activity; little information exists, however, about the alterations in blood pressure variability in this syndrome, especially during excitatory manoeuvres such as tilting or exercise. DESIGN AND METHODS: Nine patients with CHF (age 62+/-1 years, NYHA class II-III, ejection fraction 33+/-1%, peak VO2 14.1+/-3.2 ml/min per kg body weight [mean +/- SEM]) and eight healthy control subjects (age 58+/-1 years) with normal left ventricular function were studied. Blood pressure (Finapres), R-R interval (ECG) and respiration (nasal thermistor) were recorded during 15-min periods of supine rest, 70 degree head-up tilting, submaximal bicycling exercise and post-exercise recovery. Total variance and the power of the spectral components of blood pressure (HF, respiratory-related; LF, 0.03-0.14 Hz; and VLF, 0.02-0.003 Hz) were measured. RESULTS: Compared with control subjects, CHF patients have, first, a normal overall blood pressure variability during supine rest but a failure to increase this variability in response to head-up tilt and exercise; second, a suppressed LF spectral component of blood pressure at rest and in response to head-up tilt and exercise; and third, reappearance of LF blood pressure power during postexercise recovery. CONCLUSIONS: In CHF patients, overall blood pressure variability and its LF spectral component are altered at rest and during sympathoexcitatory manoeuvres. Somewhat paradoxically, however, the depressed LF blood pressure power is partially restored during a 15-min recovery period, indicating that at least part of the CHF-related alterations of blood pressure variability have the potential to revert back towards normal under appropriate physiological circumstances.
