Safety and efficacy of sonicated albumin microspheres in perfusion and vein graft patency assessments

Abstract

This study was designed to identify a concentration of sonicated albumin microspheres that is safe, useful in determining graft patency, and provides an estimate of regional myocardial perfusion. The study included 8 patients between 50 and 72 years of age who were undergoing coronary artery bypass grafting. All patients were hemodynamically stable with left ventricular ejection fractions ≥ 0.35. None had congestive heart failure or myocardial infarction with in 4 months prior to the study. All had normal baseline neurologic and renal functions, and none had experienced allergic reactions to blood products or contrast dyes. A standard median sternotomy was performed for exposure of the heart at surgery, and saphenous veins were harvested and used for grafting. Intraoperative epicardial echocardiography (EE), always in the left ventricle short‐axis at midpapillary level, was performed before and after grafting to determine regional myocardial wall motion. Sonicated albumin microspheres were prepared and injected into a single vein graft using an 18‐gauge needle; 20 3 106, 100 3 106, and 200 3 106 microspheres were injected into the first graft sequentially. All other vein grafts were injected once with the dose that gave optimal contrast enhancement in the initial graft studied. In each patient, a minimum of 3 and maximum of 5 injections were performed, and graft perfusion was studied using EE. Graft flow, blood pressure, and electrocardiographic (ECG) measurements were continuously monitored, with a final EE performed after weaning the patient off cardiopulmonary bypass to assess wall motion. Preliminary results showed that no patient had adverse effects during or after the study and all remained hemodynamically stable. No significant arrhythmias or ECG changes were recorded up to 72 hours postoperatively. Although hyperemia occurred immediately after 13 injections, in all cases it was mild and graft flow returned rapidly to baseline. Graft pressure and wall motion remained unchanged. The best contrast perfusion images, as measured by time—intensity curves, were obtained with injecting 1 ml of the 100 3 106 microspheres/ml solution. We conclude that sonicated albumin microspheres are a safe and effective contrast agent to assess regional myocardial perfusion and vein graft patency using EE. Copyright © 1991 Wiley Periodicals, Inc.