IDENTIFYING THE CAUSE OF LEFT-VENTRICULAR SYSTOLIC DYSFUNCTION AFTER CORONARY-ARTERY BYPASS-SURGERY - THE ROLE OF MYOCARDIAL CONTRAST ECHOCARDIOGRAPHY

Objective: Intraoperative myocardial contrast echocardiography was use d to determine whether the identification of regional myocardial flow patterns during revascularization could predict myocardial contractile function immediately after separation from cardiopulmonary bypass (CP B) and at 1 month after coronary artery bypass grafting (CABG) surgery . Design: A prospective, open-labeled, longitudinal analysis. Setting: Two independent university hospitals. Participants: Twenty patients, during and up to 1 month after CABG. Interventions: The contrast agent Albunex (Mallenckrodt Medical, Inc, St Louis, MO) was injected into t he aortic root during CPB. Measurements and Main Results: Myocardial c ontrast echocardiography opacification of flow was graded from intraop erative transesophageal echocardiographic images of the left ventricle in the short-axis, midpapillary view. The same myocardial images were also evaluated for regional wall motion abnormalities at 15, 30, and 60 minutes, 24 hours, 5 to 8 days, and 1 month after CPB. Logistic reg ression analysis was used to analyze the flow scores and regional func tion data from identical segments. Regional flow represented by contra st enhancement was assessed in 70% of the myocardial regions (55 of 80 possible segments; 95% confidence interval [CI], 61 to 76). Flow was more easily evaluated in the posterior region (95%) than in the anteri or (70%) or septal regions (60%), and least likely evaluated in the la teral regions (50%). Regional wall motion was scored in 84% of the myo cardial regions (469 of 560 possible regions). Function (segmental wal l motion) was assessed in all regions with equal success. Segmental fu nction and flow scores were matched to the same regions 66% of the tim e (53 of 80 possible series; 95% CI, 55 to 76). Regional myocardial co ntrast flow patterns did not predict myocardial function at 15, 30, or 60 minutes after separation from CPB. However, contrast opacification of flow did predict regional myocardial function at 1 week (p less th an or equal to 0.05) and at 1 month (p less than or equal to 0.01) aft er CABG surgery. The probability that myocardial function would be nor mal at 1 month was 0.62 when intraoperative flow opacification was abn ormal and 0.98 when flow opacification was normal. For patients with n ormal flow, the estimated odds of having normal myocardial function we re 3.33 times those of patients with abnormal flow at 1 week (odds rat io, 3.33; 95% CI, 1.09 to 10.19) and 18.5 times those of patients with abnormal flow at 1 month (95% CI, 2.44 to 140.48). Conclusion: Intrao perative application of myocardial contrast echocardiography to determ ine regional flow patterns after revascularization may help differenti ate conditions of left ventricular systolic dysfunction immediately af ter separation from CPB for CABG surgery and appear to predict myocard ial function at 1 month. Copyright (C) 1998 by W.B. Saunders Company.