TRANSIENT ISCHEMIA DOES NOT LIMIT SUBSEQUENT ISCHEMIC REGIONAL DYSFUNCTION IN HUMANS - A TRANSESOPHAGEAL ECHOCARDIOGRAPHIC STUDY DURING MINIMALLY INVASIVE CORONARY-ARTERY BYPASS-SURGERY

Objectives. This study sought to assess the effects of sequential coro nary artery occlusion during minimally invasive coronary artery bypass graft surgery (CABG) on hemodynamic variables and left ventricular sy stolic function by means of transesophageal echocardiography (TEE). Ba ckground. Clinical and experimental studies suggest a protective effec t of ischemic preconditioning in patients with acute coronary syndrome s. However, the effect of repetitive myocardial ischemia on myocardial mechanical function in humans is not completely understood. Methods. Seventeen patients with left anterior descending coronary artery (LAD) stenosis greater than or equal to 70% and normal rest left ventricula r systolic function referred for minimally invasive CABG underwent int raoperative TEE for assessment of regional left ventricular wall motio n and measurement of hemodynamic variables at baseline (baseline 1), d uring a 5-min coronary occlusion (occlusion 1), after a 5-min reperfus ion period (baseline 2) and a during a second coronary occlusion durin g bypass anastomosis (occlusion 2). Results. Left ventricular wall mot ion score (LVWMS) increased significantly from baseline (16.0) to occl usion 1 (21.4 +/- 3.1 [mean+/-SD], p < 0.05) and occlusion 2 (21.8 +/- 3.1, p < 0.05). No difference in LVWMS was noted between occlusions 1 and 2. Pulmonary artery systolic pressure increased significantly fro m baseline (25 +/- 6 mm Hg) to occlusion 1 (32 +/- 7 mm Hg, p < 0.05) and occlusion 2 (33 +/- 6 mm Hg, p < 0.05). Pulmonary artery diastolic pressure also increased significantly from baseline (12 +/- 4 mm Hg) to occlusion 1 (16 +/- 4 mm Hg, p < 0.05) and occlusion 2 (16 +/- 1 mm Hg, p < 0.05). No significant differences in pulmonary artery pressur es were noted between occlusions 1 and 2. Conclusions. Ischemic dysfun ction was precipitated by the 5-min LAD occlusion, as shown by the inc rease in LVWMS and pulmonary artery pressure. However, a 5-min coronar y occlusion and the resulting ischemia do not alter regional left vent ricular systolic function during subsequent ischemia in humans. (C)199 8 by the American College of Cardiology.