Despite its overwhelming popularity and favorable influence on perioperative clinical decision making and outcome, the transesophageal echocardiographic (TEE) approach to a comprehensive echocardiographic examination may be limited by impaired imaging of the distal ascending aorta and aortic arch, difficulty in advancing the probe within the esophagus in some patients, and contraindications for probe placement in those with gastroesophageal pathology. Furthermore, TEE may be rarely associated with perioperative morbidity from oropharyngeal and gastroesophageal injury.1,2 In recognition of these potential limitations, the Society of Cardiovascular Anesthesiologists (SCA), American Society of Anesthesiologists (ASA), and American Society of Echocardiography (ASE) currently recommend that advanced intraoperative ultrasonographers also become familiar with epicardial echocardiography and epiaortic ultrasound in addition to TEE.3,4 The ASE and SCA have subsequently published guidelines specifically focused on acquisition techniques and indications for both epicardial echocardiography and epiaortic ultrasonography.5,6 Thus, while TEE remains the most frequently used intraoperative tool for imaging cardiac and intrathoracic vascular structures, it is imperative for an experienced intraoperative ultrasonogapher to also be familiar with other imaging modalities including epicardial echocardiographic and epiaortic ultrasound techniques in order to conduct a comprehensive perioperative echocardiographic examination.
Epicardial and epiaortic imaging are performed by placing the ultrasound transducer on the surface of the heart or aorta, respectively, to acquire two-dimensional (2D), and color-flow and spectral Doppler images in multiple planes. Due to the proximity of the probe to the heart, these techniques typically use higher frequency probes (5 to 12 MHz). Epicardial and epiaortic imaging require adherence to strict sterile technique while manipulating the probe within the operative field. Consequently, these images may only be obtained by an operator who is wearing a sterile gown and gloves. The probe is placed in a sterile sheath along with sterile acoustic gel or saline in order to optimize acoustic transmission. Warm sterile saline can be poured into the mediastinal cavity to further enhance acoustic transmission from the probe to the cardiac or aortic surface. Additional manipulation of depth, transmit focus, gain, and transducer frequency may be required to optimize the image.
The ASE/SCA guidelines currently recommend that the following seven epicardial echocardiographic imaging planes be obtained to perform a comprehensive 2D and Doppler echocardiographic evaluation.5 However, the guidelines also recognize that individual patient characteristics, anatomic variations, or time constraints may limit the ability to obtain every component of the recommended comprehensive epicardial echocardiographic examination. Furthermore, modification of the recommended views may be required to obtain a more detailed interrogation of specific anatomy or pathology.
Epicardial Aortic Valve Short-Axis View
The ultrasound transducer is placed on the aortic root above the aortic valve (AV) annulus, with the ultrasound beam directed towards the AV in a short-axis (SAX) orientation to obtain the epicardial AV SAX view (Figure 20–1). Appropriate transducer alignment requires up to 30° of clockwise rotation with the orientation marker (indentation) on the transducer directed toward the patient's ...