The jugular veins provide an important index of right heart pressures and cardiac function. Jugular venous pressure ( JVP) reflects right atrial pressure, which in turn equals central venous pressure and right ventricular end-diastolic pressure. The JVP is best estimated from the right internal jugular vein, which has the most direct channel into the right atrium. Some affirm that the right external jugular vein can also be used.30 Because the jugular veins lie deep to the sternocleidomastoid (SCM) muscles, learn to identify the pulsations they transmit to the surface of the neck, briefly described below, and measure their highest point of oscillation.
Changing pressures in the right atrium during diastole and systole produce oscillations of filling and emptying in the jugular veins, or jugular venous pulsations (Fig. 1). Atrial contraction produces an a wave in the jugular veins just before S1 and systole, followed by the x descent of atrial relaxation. As right atrial pressure begins to rise with inflow from the vena cava during right ventricular systole, there is a second elevation, the v wave, followed by the y descent as blood passively empties into the RV during early and middiastole.
FIGURE 1. Jugular venous pulsations.
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