MYOCARDIAL CONTRAST ENHANCEMENT AFTER IV OPTISON[trade mark sign] FOR INTRAOPERATIVE ECHOCARDIOGRAPHY DURING CARDIAC SURGERY

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Introduction. Since 1998, Optison[trade mark sign], a venous ultrasound contrast agent of albumin micro-spheres filled with octafluoropropane, has been available to improve left ventricular (LV) endocardial border delineation. Optison[trade mark sign] was used to show myocardial perfusion in dogs. Contrast agents injected arterially have been used in humans to show myocardial perfusion. The noninvasive demonstration of myocardial perfusion during cardiac surgery with transesophageal echocardiography (TEE) would be helpful in distinguishing stunned but perfused from ischemic myocardium. Methods. 23 patients (pts) undergoing valvular surgery with normal coronary anatomy were studied. Two different echo systems equipped for on-line measurement of reflected ultrasound energy in a user defined region of interest (ROI) [Acuson Aspen[trade mark sign] (AA) and Hewlett Packard Sono 5500[trade mark sign] (HP)] were used to measure contrast intensity. In a transgastric shortaxis view of the LV, the ROI was placed in the inferior wall, and a bolus of 0.3 ml of Optison[trade mark sign] was injected into a central vein while contrast intensity was measured and recorded. Imaging was triggered by electrocardiography and ventilation interrupted to eliminate motion artifacts during image acquisition. Results. In 2 of 30 injections in 11 pts imaged with the AA system, increases in myocardial contrast intensity were seen in 2 pts. In 12 of 42 injections in 12 pts imaged with the HP system, increases in myocardial contrast intensity were seen in 5 pts, with the most dramatic response shown (Figure 1). In 3 of these pts, effects were repeatable in multiple injections, while one patient showed increased myocardial contrast intensity only during a dobutamine infusion. 16 pts (9 imaged with AA, 5 with HP) showed no contrast effect on multiple contrast injections.Figure 1Discussion. We inconsistently detected increased myocardial contrast intensity in the LV inferior wall after IV injection of Optison[trade mark sign]. This effect was not repeatable in all pts and was never seen in others. Some of the differences seen might be due to the methods used by the echo systems to measure and process reflected ultrasound energy into data. Also, in 6 of 11 pts imaged with the AA system we triggered at every heart beat, which might have caused accelerated destruction of microspheres, thereby unabling us to measure contrast effect. All other studies were triggered at every 4th heart beat. More study and technical advances are needed to make myocardial contrast echocardiography a reliable, reproducible technique for the intraoperative setting.