LEFT-VENTRICULAR FUNCTION IN DOGS 1 YEAR AFTER COARCTECTOMY

Juxtaductal aortic coarctation was surgically created in beagle puppies at the age of 2 months and resected at the age of 10 months, after the development of good collateral circulation. Control dogs undergoing sham operations on each occasion were studied in the same environment. Cardiac catheterization was performed 1 year after the coarctectomy to evaluate the recovery of the heart. Cardiac output, heart rate, end-diastolic pressure, and V(max) were similar in both groups of seven dogs, but the systolic pressure gradient (SPG) over the operated area during isoproterenol infusion was significantly higher in the coarctectomized group, with a mean of 8.9 +/- 6.3 (SD) vs. 0.1 +/- 0.3 mmHg (p < 0.05). The preejection period [PEP, 58 +/- 8 vs. 47 +/- 5 ms (p < 0.01)], electromechanical delay [EMD, 18 +/- 3 vs. 13 +/- 3 ms (p < 0.05)], and isometric contraction time [ICT, 39 +/- 7 vs. 32 +/- 4 ms (p < 0.05)], were all significantly longer in the coarctation group after isoproterenol infusion. The results demonstrate that, even though cardiac output increased adequately during loading and mechanical pumping efficiency was preserved, excitation-contraction coupling was still prolonged. Thus, an anatomical successful coarctectomy, even at the age of 10 months, does not fully restore left ventricular function in dogs after chronic experimental coarctation.