Left ventricular response to isometric exercise in patients with denervated and innervated hearts

Patients with cardiac denervation resulting from allograft transplantation have been observed to increase their diastolic and systolic blood pressure during isometric exercise without concomitant cardioacceleration. To determine the mechanism for the blood pressure increase, heart rate, blood pressure, and ventricular volumes (measured using fluoroscopy of tantalum midwall myocardial markers) were recorded before and after a 50% maximal voluntary contraction. Seven cardiac transplant recipients (denervated heart) and seven nontransplant patients (innervated heart) were studied. Innervated and denervated heart patients increased systolic blood pressure by 16% and 21% and total peripheral resistance by 20% and 12%, respectively. The percentage responses were not significantly different between groups, except for heart rate, which increased 17% in innervated heart patients and 2% in denervated heart patients (p less than 0.05). Neither group had enhanced contractility or increases in cardiac output, suggesting that the blood pressure increases resulted in both groups from increased peripheral resistance.