The Jugular Venous Pressure and Pulse Contour

Information that can be derived from an assessment of the jugular venous pulse includes determination of the mean venous pressure, venous pulse contour, and presence and type of cardiac dysrhythmias. The jugular venous pressure is usually assessed by observing the right side of the patient's neck. The mean jugular venous pressure, determined as the vertical distance above the midpoint of the right atrium, is 6 to 8 cm HO. Deviations from this normal range reflect either hypovolemia (i.e., mean venous pressure less than 5 cm HO) or impaired cardiac filling (i.e., mean venous pressure greater than 9 cm HO). The normal jugular venous pulse contains three positive waves. By convention these are labeled "a," "c", and "v" (Figure 19.1). These positive deflections occur, respectively, before the carotid upstroke and just after the P wave of the ECG (a wave); simultaneous with the upstroke of the carotid pulse (c wave); and during ventricular systole until the tricuspid valve opens (v wave). The a wave is generated by atrial contraction, which actively fills the right ventricle in end-diastole. The c wave is caused either by transmission of the carotid arterial impulse through the external and internal jugular veins by the bulging of the tricuspid valve into the right atrium in early systole. The v wave reflects the passive increase in pressure and volume of the right atrium as it fills in late systole and early diastole. Normally the crests of the a and v waves are approximately equal in amplitude. The descents or troughs (Figure 19.1) of the jugular venous pulse occur between the "a" and "c" wave ("x" descent), between the "c" and "v" wave ("x" descent), and between the "v" and "a" wave ("y" descent). The x and x′ descents reflect movement of the lower portion of the right atrium toward the right ventricle during the final phases of ventricular systole. The y descent represents the abrupt termination of the downstroke of the v wave during early diastole after the tricuspid valve opens and the right ventricle begins to fill passively. Normally the y descent is neither as brisk nor as deep as the x descent. in the jugular venous pulse may be reflected in either the mean pressure, amplitude, or configuration of the positive waves or negative troughs, or in the sequence or absence of the positive waves. In this chapter emphasis is placed on measurement of the jugular venous pressure, use of the venous pulse to determine cardiac rhythm, and the more common cardiac problems of pulmonary hypertension, tricuspid regurgitation, and constrictive pericarditis.