Multiple studies have shown the ability of emergency phy-sicians to accurately evaluate cardiac function and ejection fraction.^3,⁴ When compared with cardiologists, emergency physicians were found to have a correlation coefficient of 0.86 with cardiologists when assessing ejection fraction. Cardiologists had a similar coefficient of 0.84 among themselves.

Diagnosis of Pericardial Effusion

Emergency physicians have proved to be accurate in the diagnosis of pericardial effusion. Previous research has shown that emergency physicians have a sensitivity of 96%⁵ to 100%⁶ as compared with formal overreading by trained echocardiographers.

How to Scan/Scanning Protocols

Probe Selection

Classic echocardiography requires the use of a phased-array probe, sometimes referred to as the thoracic probe. These probes have a small footprint and are ideal for achieving visualization with a small acoustic window between ribs.

Acoustic Windows

Bedside cardiac ultrasound is typically taught with the use of three separate acoustic windows and multiple orthogonal views within the windows. These acoustic windows include the parasternal, apical, and subcostal. Each window is then broken down into orthogonal views, including the parasternal long-axis, parasternal short-axis, apical four-chamber, apical two-chamber, apical long-axis, subcostal four-chamber, and subcostal long-axis views.

Probe Orientation

Echocardiography places the probe marker on the right side of the ultrasound screen so that when the ultrasound machine is in the cardiac mode, the right-hand side of the screen indicates the side of the probe with the marker on it (this is opposite any other scanning mode).

The parasternal long-axis view seen in Figure 5.1 is obtained by placing the probe in the third to fourth intercostal space with the probe marker pointed toward the patient’s right shoulder (Figs. 5.2 and 5.3). The long axis of the heart should be horizontal on the screen with the apex pointed to the left. If the apex is pointed up, the probe is too low and should be moved up an interspace. This view allows visualization of the left ventricle, mitral valve, left atrium, right ventricular outflow tract, aortic valve, and aorta. The descending thoracic aorta is often visualized posterior to the left ventricle in transection.

Fig. 5.1 Parasternal long-axis view of a normal-appearing heart.

Fig. 5.2 Parasternal long-axis diagram.

Ao, Aorta; LA, left atrium; LV, left ventricle; RVOT, right ventricular outflow tract.

Fig. 5.3 Probe orientation for the parasternal long-axis view.

Parasternal Short Axis

The parasternal short-axis view is obtained by rotating the probe 90 degrees from the parasternal long-axis position so that the probe marker is pointed to the patient’s left shoulder (Figs. 5.4 and 5.5). The ultrasound beam is now transecting the heart in its short axis. If the physician tilts the probe so that it is pointing to the base of the heart, the aortic valve is visualized along with the “inflow and outflow” of the right heart. This view includes the right atrium, right ventricular outflow tract, and pulmonic valve. As the probe is tilted more apically, the aortic valve is lost and a cross-sectional view of the mitral valve is obtained (Fig. 5.6). At this point the right ventricle becomes more apparent and takes a position as a crescentic ventricle to the left and superficial to the mitral valve and left ventricle. Finally, as the probe is tilted more toward the apex, the mitral valve is lost and the muscular portion of the left ventricle is visualized. The posterior medial and anterior papillary muscles are visualized at this point, and the circular nature of the left ventricle can be appreciated (Fig. 5.7).