Alterations of systemic haemodynamics in experimental renovascular hypertension in dogs of different ages.

Renovascular hypertension [bilateral simultaneous stenosis of renal arteries] was produced in 35 dogs of different ages [18--22 days, 2--3 months, 3--5 years]. On days 3 and 14 of renal ischaemia, the alterations were investigated that had occurred in the arterial pressure, cardiac output, stroke volume, total peripheral vascular resistance [TPVR], left ventricular work, and other haemodynamic indicators. It was found that the more marked elevation of arterial pressure in puppies was connected not only with increased TPVR, but also with enhanced cardiac output and stroke volume, whereas in mature animals at increased TPVR the cardiac output and stroke volume were reduced. The authors ascribe the differences in haemodynamic changes to age-dependent differences in intracardiac compensation, autonomous regulation of heart function, and the functional state of the renin-angiotensin system.