No abstract

Over the past decades, echocardiography has undergone a continuous evolution in technology that has promoted its clinical application and acceptance throughout perioperative medicine. These technological advances include improvements in transducer development that permit superior imaging quality and a wider selection of probes for epicardial, epiaortic, and surface echocardiography which can also be used in conjunction with multiplane transesophageal echocardiography. Moreover, the addition of Doppler technology and digital acquisition has secured the role of echocardiography as a valuable and relatively noninvasive diagnostic tool for the assessment of cardiovascular disease and hemodynamic monitoring throughout the perioperative period. Therefore, it has become increasingly important for perioperative physicians to understand the basic principles and underlying fundamental concepts pertaining to the technology and physics of echocardiography, as well as its inherent limitations. The current review outlines the modes and applications of different echocardiographic techniques used in perioperative echocardiography including M-mode, two-dimensional echocardiography, and Doppler assessment of blood flow. In addition, the limitations of these techniques and typical artifacts associated with the perioperative use of echocardiography are described.

Epicardial echocardiography has been available since the early 1970s as an intraoperative diagnostic modality to assess ventricular and valvular function. With this technique, an ultrasonic transducer is placed directly on the epicardial surface of the heart, following sternotomy and pericardiotomy. Under the guidance of the cardiac anesthesiologist, the surgeon places the transducer so that the desired views of cardiac structures and great vessels can be obtained. The anesthesiologist performs the acquisition, analysis and interpretation of the echocardiographic images. Despite the feasibility of epicardial echocardiography, transesophageal echocardiography (TEE) has emerged over the last two decades as the main form of intraoperative echocardiography. Although TEE allows continuous monitoring of cardiac and valvular function without interruption of the surgical procedure, placement of a TEE probe may be difficult or contraindicated in some patients. In such cases, epicardial echocardiography may be the optimal ultrasonographic imaging modality to assess ventricular and valvular function during cardiac surgery. We describe the use of epicardial echocardiography for intraoperative assessment of valvular function in two patients where TEE was either contraindicated or probe placement could not be performed safely. The first patient underwent surgical repair of the mitral valve for severe mitral regurgitation. After weaning the patient from cardiopulmonary bypass (CPB), epicardial echocardiography was used to confirm successful reconstruction of the valve and to exclude residual mitral regurgitation. The second patient was scheduled for coronary artery bypass grafting (CABG). Prior to the initiation of CPB, the presence of moderate aortic stenosis was confirmed using Doppler echocardiography via an epicardial approach.