Ultrasound of the heart, or echocardiography (echo), is among the most challenging sonographic examinations to master. However, with goal-directed training clinicians can quickly and accurately answer some of the most critical questions using point-of-care echo:
- Is the heart pumping (and how well?)
- Is there significant fluid around the heart (pericardial effusion)?
Beyond these basic questions there is a wealth of information that echo can provide in critical care and emergency patients. The challenge is defining what can reliably be diagnosed based on the sonographer's experience. Understanding limitations and obtaining consultant-performed echo when available and appropriate is essential.
Echo should be used liberally in patients in whom a pericardial effusion is suspected. This includes patients presenting with chest pain, shortness of breath, tachycardia, hypotension, or syncope. Echo can expedite life-saving care in penetrating chest trauma. In a code or near-code situation, echo can rapidly identify some of the reversible causes of pulseless electrical activity (PEA). The finding of an enlarged heart on chest x-ray is an excellent indication for point-of-care echo, as this tends to be heart failure or pericardial effusion—both of which are readily diagnosed with echo but can be difficult to differentiate by physical exam and respond to very different treatments.
Echo may be easily integrated into algorithms for point-of-care sonography that include multiple goal-directed examinations, each designed to answer specific binary questions that can directly affect patient management. The extended focused assessment by sonography for trauma (FAST) exam includes goal-directed examinations of the peritoneum, pelvis, pleural cavities, as well as echo. Other indications where point-of-care echo should be incorporated into a diagnostic algorithm include unexplained hypotension (Chap. 25) and unexplained dyspnea (Chap. 26).
This section focuses on transthoracic echo (TTE). TTE is readily performed as a point-of-care examination at the bedside. While the anatomy and pathology remain the same, transesophageal echo (TEE) may provide superior images and diagnostic sensitivity, although it is more invasive, more technically challenging, and requires special equipment, sedation, and attention to airway management. Point-of-care TEE may be very helpful in a critically ill patient who is already endotracheally intubated.
The heart is best thought of as a cone, with a base and apex (Figs. 6-1 and 6-2a and b). The base, which contains the valves and atria, is positioned posteriorly and toward the right shoulder. The apex, where the ventricles come to a point, is directed obliquely and anteriorly toward the left hip. Thus, the "long axis" of the heart is a line or plane directed from the right shoulder to the left hip. The "short axis" is perpendicular to the long axis, a line or a plane directed from the left shoulder to the right hip. Recalling geometry, when an ultrasound plane cuts through a cone along its axis a triangle results (long-axis view) (Fig. 6-3a), while when a plane cuts through a ...