The Venous Pulse

An accurate assessment of the venous pulse is an integral part of the physical examination because it provides information concerning both the mean right atrial pressure and the hemodynamic events in the right atrium.165 Factors influencing the right atrial and central venous pressure (CVP) include the total blood volume, thedistribution of blood volume, and the strength of right atrial contraction.

Venous blood returning from the systemic capillaries is nonpulsatile. Changes in volume flow created by skeletal muscles and the respiratory pump are nonsynchronous with the pulsatile activity of the heart. Changes in flow and pressure caused by right atrial and ventricular filling, however, produce pulsations in the central veins that are transmitted toward the peripheral veins, opposite to the direction of blood flow. With the possible exception of the c wave, which is the combined result of carotid arterial impact and an upward movement of the tricuspid valve, the pulsations observed in the neck are produced by right atrial and ventricular activity.195

Examination of the Jugular Venous Pulse

The two main objectives of the bedside examination of the neck veins are estimation of the CVP and inspection of the waveform.197 Usually, the right internal jugular vein is superior for both purposes. In most normal subjects, the maximum pulsation of the internal jugular vein is observed when the trunk is inclined by less than 30°. In patients with an elevated venous pressure, it may be necessary to elevate the trunk further, sometimes to as much as 90°. When the neck muscles are relaxed, shining a beam of light tangentially across the skin overlying the internal jugular vein often exposes its pulsations. Simultaneous palpation of the left carotid artery aids the examiner in deciding which pulsations are venous.

Measurements of Venous Pressure

The difference between venous distention and venous pressure elevation must be considered. Veins may be markedly dilated with minimal increase in pressure or may not be visibly distended despite a very high venous pressure.196 Venous pressure may be estimated by examining the veins on the dorsum of the hand. With the patient sitting or lying at a 30° elevation or greater, the arm is slowly and passively raised from a dependent position. When the venous pressure is normal, the veins collapse when the dorsum of the hand reaches the level of the sternal angle of Louis. Unfortunately, local venous obstruction or augmented peripheral venous constriction may diminish the accuracy of estimating CVP by this method.

The external or internal jugular veins also may be used to estimate venous pressure.196 Because of its more direct route to the right atrium, the internal jugular vein is superior for the estimation of venous pressure and assessment of the venous waveform. The patient is examined at the optimal degree of trunk elevation for visualization of venous pulsations. The vertical distance from the top of the oscillating venous column to the level of the sternal angle is generally less than 3 cm. Greatly elevated venous pressure may be missed by failing to elevate the patient's head adequately. It may be necessary to actually have the patient sit upright. If the "pulsating meniscus" is very high, pulsations may not be apparent in the lower neck. When venous engorgement is marked, the patient's earlobe may pulsate, and even the veins on the top of the head may be distended.

In patients suspected of RV failure but having a normal resting venous pressure, the abdominojugular test is useful.196 With the patient breathing normally, firm pressure is applied with the palm of the hand to the upper right quadrant of the abdomen for 10 s or more. The patient should be instructed to continue to breathe normally during the test. In most subjects, the jugular venous pressure is not altered significantly. In some normal patients there is a transient increase in jugular venous pressure with a rapid return to or near baseline in less than 10 s. The dysfunctioning right ventricle, however, is unable to accept the increment in blood volume due to enhanced venous return without a marked increase in its filling pressure, which is transmitted to the neck veins. In patients with RV failure, which often results from left-sided heart failure, the venous pressure either rises rapidly and then partially declines slowly during continued abdominal compression or remains elevated by 4 cm of blood or more until the abdominal pressure is released (&H0; Fig. 10-44). Ducas et al.i98 also studied the abdominojugular test and confirmed its clinical value.

Analysis of Venous Waveforms

Again, the patient's trunk should be inclined to whatever elevation is necessary to reveal the top of the oscillating venous column.!" Slow, deep inspiration will increase the amplitude of the presystolic a wave while decreasing the mean right atrial pressure. This is a useful technique for identifying the site at which the pulsations will be best visualized. Simultaneous palpation of the left carotid artery and cardiac auscultation aid the examiner in relating the venous pulsations to the timing of the cardiac cycle.

Normal Venous Pulse

The normal jugular venous pulse (JVP) reflects phasic pressure changes in the right atrium and consists of three positive waves and two negatives troughs (B-H0i Fig. 10-45). It is useful to refer to the events of the cardiac cycle (Plate 2). The positive presystolic a wave is produced by right atrial (RA) contraction and is the dominant wave in the JVP, particularly during inspiration. During atrial relaxation, the venous pulse descends from the summit of the a wave. Depending on the PR interval, this descent may continue until a plateau (z point) is reached just prior to RV systole. More often, the descent is interrupted by a second positive venous wave, the c wave, that is produced by bulging of the tricuspid valve into the right atrium during RV isovolumic systole and by the impact of the carotid artery adjacent to the jugular vein.200 Following the summit of the c wave, the JVP contour declines, forming the normal negative systolic wave, the x wave. The x descent is due to a combination of atrial relaxation, the downward displacement of the tricuspid valve during RV systole, and the ejection of blood from both ventricles (see Chap. 3).

The positive, later systolic v wave in the JVP results from the increase in blood volume in the venae cavae and right atrium during ventricular systole when the tricuspid valve is closed. After the peak of the v wave is reached, the RA pressure decreases because of the diminished bulging of the tricuspid valve into the right atrium and the decline in RV pressure that follows tricuspid valve opening. In the JVP, the latter occurs at the peak of the v wave. Following the summit of the v wave, there is a negative descending limb, referred to as the y descent or diastolic collapse, which is due to the tricuspid valve opening and the rapid inflow of blood into the right ventricle. The initial y descent corresponds to the RV rapid-filling phase. The trough of the y wave occurs in early diastole and is followed by the ascending limb of the y wave, which is produced by the continued diastolic inflow of blood into the right side of the heart. The velocity of this ascending pressure curve depends on the rate of venous return and the distensibility of the chambers of the right side of the heart. When diastole is long, the ascending limb of the y wave is often followed by a small, brief, positive wave, the h wave, that occurs just prior to the next a wave. At times, there is a plateau phase rather than a distinct h wave. With increasing heart rate, the y trough and y ascent are followed immediately by the next a wave.

Usually, there are three visible major positive waves (a, c, and v) and two negative waves (x and y) when the pulse rate is below 90 beats per minute and the PR interval is normal. With faster heart rates, there is often fusion of some of the pulse waves, and an accurate analysis of the waveform is more difficult.

Abnormal Venous Pulse

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