DIURNAL-VARIATION IN BLOOD-PRESSURE IN PATIENTS WITH BIVENTRICULAR ASSIST DEVICES AND RETAINED, NONPUMPING NATIVE HEARTS

Background Studies indicate that centrally mediated rhythms in sympath etic tone play a prominent role in diurnal cardiovascular variability. Recent evidence from heart transplant recipients, in whom blood press ure does not decline during sleep despite normal variability in plasma norepinephrine, however, suggests that afferent cardiac nervous traff ic is necessary for the generation of diurnal variability. This implie s that in the presence of an innervated heart excluded from the system ic circulation, blood pressure would still decrease during sleep. To a ssess this hypothesis, we studied 24-hour blood pressure, heart rate, and neuroendocrine variability in patients with biventricular assist d evices in whom the retained native hearts had ceased to pump. Methods and Results Eight patients were free of medication and were studied ev ery 3 hours. Pump rates and output were kept constant throughout the s tudy. Blood pressure showed a significant decline during sleep, as did norepinephrine and epinephrine (all P<.05). Atrial natriuretic factor showed a significant increase around midnight (P<.01). Significantly elevated levels were found for all hormones studied except for aldoste rone and endothelin. Conclusions Our results suggest that diurnal vari ations in cardiac function or in catecholamine levels (indicative of s ympathetic activity) as found in cardiac transplant recipients alone a re not responsible or sufficient for producing a nocturnal drop in blo od pressure. The presence of an innervated heart appears crucial in th is respect. This could be of importance for the understanding of circa dian cardiovascular pathophysiology.