Pericardial tamponade is arguably the most dramatic ultrasound (US) finding for the Emergency Physician (EP). The diagnosis is difficult to make without cardiac US, and acute intervention can be lifesaving. Cardiac US has proven to be an invaluable tool for identifying critical pathology and directing decision making in the Emergency Department (ED).1 A quick bedside US can assess a patient's cardiac activity, global cardiac function, presence or absence of effusion, and volume status. Cardiac US is an essential part of the evaluation of the trauma patient,2 the cardiac arrest patient,3,4 and the patient with undifferentiated hypotension.5,6
Cardiac ultrasonography can be one of the most challenging areas of emergency US. The EP must have a keen grasp of the spatial anatomy of the heart to properly perform and interpret the US examination. An EP can become competent in basic cardiac ultrasonography with practice. This tool can be utilized to gain great insight into the body's most vital organ. This chapter will cover basic cardiac anatomy, the indications for emergency echocardiography, techniques, and image interpretation.
General Anatomy and Physiology
It is essential to know the anatomy of the heart before performing any US examination (Figure 29-1). The heart 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; 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.
The cardiac anatomy. The long axis of the heart (long arrow) extends from the base to the apex. The short axis (short arrow) is a transverse slice perpendicular to the long axis.
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. Blood flows from ...