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Cardiac ultrasound (US) or basic echocardiography has been proven to be an invaluable tool for identifying critical pathology and directing decision making in the Emergency Department (ED).1 Cardiac US is a key element in the evaluation of the trauma patient, the cardiac arrest patient, and the patient with undifferentiated hypotension.2-6 Even though cardiac ultrasonography can be challenging, an Emergency Physician (EP) can become competent in basic cardiac ultrasonography with practice. The EP must have a keen grasp of the spatial anatomy of the heart to properly perform and interpret the US examination. Cardiac US can help EPs to risk-stratify patients and guide resuscitative efforts. Pericardial tamponade is a difficult diagnosis to make without cardiac US. A quick bedside US can assess a patient’s cardiac activity, global cardiac function, presence or absence of an effusion, and volume status. This chapter will cover basic cardiac anatomy, the indications for emergency echocardiography, techniques, and image interpretation.
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ANATOMY AND PATHOPHYSIOLOGY
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GENERAL ANATOMY AND PHYSIOLOGY
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It is essential to know the anatomy of the heart before performing any US examination (Figure 37-1). The heart is a three-dimensional organ that lies obliquely in the middle of the chest. It consists of four chambers: the left atrium, the right atrium, the left ventricle, and the right ventricle. The atria are thin-walled muscular structures. The ventricles are more voluminous and muscular, with the left ventricle having the thickest wall. The base of the heart is the superior portion. It is formed by the left atrium and, to a lesser extent, the right atrium. The apex of the heart consists of the inferolateral portion of the left ventricle. The anterior surface of the heart abuts the chest wall and is mainly formed by the right ventricle. The left ventricle forms the majority of the inferior surface, with the inferior portion of the right ventricle making a minor contribution. The heart has two axes, and both are used extensively in ultrasonography. The long axis extends from the base to the apex, roughly along a line from the right shoulder to the left hip. The short axis slices the heart transversely and perpendicular to the long axis, roughly along a line from the left shoulder to the right hip.
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The right heart delivers blood to the lungs to be oxygenated, and the left heart distributes it to the rest of the body. The right atrium receives deoxygenated blood from the body via the superior and inferior vena cava (IVC). Blood flows from the right atrium through the tricuspid valve and into ...