Nitroglycerin to unmask reversible asynergy. Correlation with post coronary bypass ventriculography.

The value of nitroglycerin in determining the potential reversibility of asynergy was examined in 35 patients with coronary heart disease. Ventriculograms performed at rest and after sublingual nitroglycerin were analyzed for (1) location of asynergy relative to distribution of the 3 major coronary arteries and (2) severity of asynergy. Of the 41 hypokinetic zones, 30 (73%) improved following nitroglycerin. Of 28 akinetic zones, 16 (57%) improved (7 of the 16 segments becoming normal) following nitroglycerin. None of 7 dyskinetic zones showed change following nitroglycerin. Twelve patients were restudied following coronary bypass surgerv. There was an excellent over-all correlation between the segments that responded to nitroglycerin and bypass surgery in those segments with open grafts. Eighteen segments which improved following nitroglycerin had patent postoperative grafts, and in 15 segments there was a corresponding improvement following bypass surgery. Two segments which were unresponsive to nitroglycerin preoperatively had patent postoperative bypass grafts. Neither segment improved despite graft patency. In summary, sublingual nitroglycerin is useful in unmasking residual contractile ability in asynergic zones. A positive response to nitroglycerin appears to be predictive of corresponding beneficial effect from a coronary bypass graft. The data strongly suggest that the use of nitroglycerin to determine residual contractile abilitv mav be of considerable value in better defining the potential risks and benefits of coronary bypass surgery.