Intraoperative evaluation of myocardial viability by nitroglycerin-induced improvement in regional left ventricular...

The aim of this study was to assess whether intraoperative transesophageal echocardiography with nitroglycerin infusion could identify viable myocardium. Twenty-eight patients with coronary artery disease with regional dysfunction underwent transesophageal echocardiography during bypass surgery. A transgastric left ventricular cross-sectional image at the midpapillary level was obtained and divided into four segments for wall motion analysis. Forty-four segments were graded as asynergic. Nitroglycerin was then given intravenously with an initial infusion rate of 1 microgram/kg/min, followed by an increase in dose up to 3 micrograms/kg/mini. Functional improvement with nitroglycerin was observed in 33 or 44 asynergic segments, while 11 remained unchanged. Follow-up transthoracic echocardiography was performed at 15.9 +/- 5.5 days after surgery. A segment was defined as viable when wall motion was better than or equal to severe hypokinesis at baseline or follow-up. Forty-three of 44 asynergic segments at baseline were defined as viable; these were the same segments demonstrating wall thickening with nitroglycerin. In particular, four of 5 akinetic segments at baseline demonstrated viability at follow-up, which had been predicted with nitroglycerin. Transesophageal echocardiography with nitroglycerin correctly identified viability (p < 0.05). No adverse hemodynamic effect was observed. Intraoperative transesophageal echocardiography with nitroglycerin appears to be a safe, noninvasive, feasible, and widely available method to identify myocardial viability under the condition supported by cardiopulmonary bypass.