A new technique facilitating intraoperative, high-frequency echocardiography of coronary bypass graft anastomoses

Abstract

FIGURE 1. Three-dimensional image of the second-generation prototype of the Echoclip device for visualization of the AP (left) and LR planes (right). The Echoclip device consists of 2 skin supports, 2 and 3,which stabilize the imaging area. Between the skin supports, a cavity, 4, is provided. The cavity may accommodate a bypass graft, an anastomosis, or a coronary vessel. Inasmuch as bypass grafts may vary in size, the distance between the skin supports may vary. Also, the height of bypass grafts may vary. To obtain a good imaging contact between the graft and the transducer, the height of the inner sides of the skin supports may vary. In addition, the cavity allows the transducer to obtain imaging. The device also comprises an aperture for receiving the transducer used together with the device. The device comprises fixing elements to ensure that the transducer is properly secured in the aperture, 1. For obtaining longitudinal and transversal sectional images, the cavity is positioned longitudinally and transThe technical quality of anastomoses during coronary artery bypass grafting is often evaluated by measuring flow rate in grafts using transit time flowmetry. Unfortunately, flow rate and flow waveform are poor indicators of the anatomy of anastomoses. Up to 9% of the anastomoses may have a stenosis of more than 50% not detected by flowmeasuring techniques. A better way to evaluate the anatomy of an anastomosis is 3-dimensional imaging. High-frequency epicardial echocardiography has the spatial and temporal resolution to produce a clear image of the anastomoses, detect intramural vessels, and ensure the optimal place for grafting. (phantom resolution of 6.5–15 MHz transducers is reported in the range of 0.1 to 0.25 mm, with approximately 4-cm penetration depth). On the basis of ex vivo porcine and human hearts, epicardial high-frequency echocardiography has a high sensitivity (0.98) and specificity (1.0) for detection of anastomotic construction errors. Three problems must be overcome in performing epicardial echocardiography on the beating heart: