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venous pulse

The evaluation of the venous pulse is an integral part of the physical examination since it it reflects both the mean right atrial pressure and the hemodynamic events in the right atrium. Factors influencing the right atrial and central venous pressure (CVP) includes to total blood volume, the distribution of blood volume, and right atrial contraction . Venous blood returning from the systemic capillaries is nonpulsatile.Changes in flow and pressure caused by skeletal muscles and respiratory pump are nonsynchronous with the pulsatile activity of the heart. Changes in flow and pressure caused by right atrial and ventricular fillingl, 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 upward movement of the tricuspid valve, the pulsations observed in the neck are produced by right atria and ventricular activity.

Examination of the Jugular Venous Pulse

The two main objectives of the bedside examination of the neck veins are the estimation of the CVP and the inspection of the waveform. 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 elevated venous pressure, it may be necessary to elevate the trunk further, sometimes as much as 90. W hen the neck muscles are relaxed, shining a beam of light tangently across the skin overlying the internal jugular vein exposes its pulsations Simultaneous palpation of the left carotid artery aids the examiner in deciding which pulsations are venous.

Measurement 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 visible distended despite a very high venous pressure. Venous pressure maybe estimated by examining the veins in the dorsum of the hand. With a patient lying or sitting in 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 angle of Louis. Unfortunately, a local venous obstruction or augmented peripheral venous constriction may diminish the accuracy of estimating CVP by this method.

The external or internal jugular vein may also be used to estimate venous pressure. 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 venous waveform. The patient is examined at the optimum 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.(3cm+5 cm)=8cm). Greatly elevated venous pressure may be missed by failing to elevate adequately the patient's head. It may be necessary to actually have the patient sit upright. If the "pulsating meniscus" is very high, pulsations may be inappropriate 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 maybe be distended. In patients suspected of right ventricular failure but having normal resting venous pressure, the abdominojugular( also known as the hepatojugular) test is useful. With the patient breathing normally, firm pressure is applied with the palm of the hand to the right upper quadrant of the abdomen for 10 or more s.The patient should be instructed to continue breathing normally during the test. In most subjects the venous pressure is not altered significantly. In some normal patients there is a transient increase in jugular venous pressure with the "rapid return" to or near baseline in less than 10 s. The dysfunctioning right ventricle, however, is unable to accept the increment of blood volume due to enhanced venous without of marked increase in its filling pressure, which is transmitted to the neck veins. In patients with right ventricular failure, which often results from left- sided heart failure, the venous pressure either rises rapidly and declined slowly during abdominal compression or remains elevated by 4 or more centimeters of blood until pressures released (figure 203-a). Ducas et al. studied the abdominal jugular test and attested to the accuracy of the test results.

Figure 203-a: Elevation in right atrial (RA) pressure observed during abdominal pressure in patient with mild congestive heart failure. (From GA Ewy: The abdominojugular test:Technique and hemodynamics correlates. Ann Intern Med 109:456,1989.

 

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. Having the patient take a 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 aids the examiner in relating the venous pulsations to the timing of the cardiac cycle.

Normal Venous Pulse

The normal venous pulse (JVP) reflects phasic pressure changes in the right atrium and consists of three positive waves and to negative troughs ( figure 203-b).In considering this pulse it is useful to refer to the events of the cardiac cycle. The positive presystolic "a" wave is produced by right atrial 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" way Depending on the PR interval, this descent may continue until a plateau ("z" point) is reached just prior to right ventricular systole. More often the descent is interrupted by a second positive venous wave, "c" wave, which is produced by a bulging of the tricuspid valve into the right atrium during right ventricular isovolumic systole and by the impact of the crowded artery adjacent to the jugular vein. Following the summit of the "c" wave, the JV P 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 right ventricular systole, and the ejection of blood from both the ventricles.

Figure 203-b: Schematic representation of the normal jugular venous pulse (JVP), four types of abnormal JVPs, and the JVPs in three arrhythmias. See text for definition of H,Z,C,X, V, and Y.

The positive, late systolic "v" wave in the JVP results from the increase in blood volume in the venae cavae and the right atrium during ventricular systole when the tricuspid valve is closed. After the peak of the "v" wave is reached, the right atrial pressure decreases because of the diminished bulging of the tricuspid valve into the right atrium and the decline in right ventricular pressure which follow tricuspid valve opening The latter occurs at the peak of the "v" wave in the JVP. 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 of opening in the rapid and flow of blood into the right ventricle. The initial "y" descent corresponds to the right ventricular 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 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 descending limb of the "y" wave is often followed by a small, brief, positive wave, the "h" wave, which occurs just prior to the next "a" wave. At times, there is a plateau phase rather than a distinct "h" wave. With increasing pulse rate the "y" trough and the "y" ascent are followed immediately by the next "a "wave.( see plate 204. ) Usually, there three visible major positive waves ("a", "c", "v") and two negative wave ("x", "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 the some of the pulse waves and an accurate analysis of the waveform is more difficult.

Plate 204: Diagram of the cardiac cycle, showing the pressure curves of the great vessels and cardiac chambers, valvular events and heart sounds, left ventricular volume curve, jugular pulse wave, apex cardiogram, and the electrocardiogram. For ilustrative purposes, the time intervals between the valvular events have been modified and the "Z" point has been prolonged. Valve motion: MC= mitral component of the first sound; MO= mitral valve opening: TC=tricuspid component of the first heart sound;TO=tricuspid valve opening: AC=aortic component of the second heart sound:AO=aortic valve opening; PC= pulmonic valve component of the second heart sound; PO= pulmonic valve; OS= opening snap of atrioventricular valves. Apex cardiogram:IC=isovolumic or isovolumetric relaxation wave; O= opening of mitral valve; RFW = rapid- filling wave; SFW=slow filling wave.

 

Abnormal Venous Pulse

Elevated Venous Pressure

The most common cause of elevated jugular venous as pressure is an increase right ventricular pressure such as occurs in patients with pulmonary stenosis , pulmonary hypertension, or right ventricular failure secondary to right ventricular infarction. The venous pressure also is elevated when obstruction to right ventricular inflow occurs,such as with tricuspid stenosis or right atrial myxoma, or when constructive pericardial disease impedes right ventricular inflow. It may also result from vena caval obstruction and, at times an increase blood volume. Patients with obstructive pulmonary disease may have an elevated venous pressure only during expiration.

Kussmal's Sign

Normally there is an increase in the "a" wave of the JVP but a decrease in the mean jugular venous pressure during inspiration as result of the increase filling of the right side chambers associated with the decline in intrathoracic pressure.An inspiratory increase in venous pressure may occur in patients with severe constrictive pericarditis when the heart is unable to accept the increase in right ventricular volume without a marked increase in the filling pressure. Although Kussmaul's sign was first described in patients with constructive pericarditis , its most common cause is severe right-sided heart failure, regardless of etiology. The presence of Kussmaul's sign is also useful in the diagnosis of right ventricular infarction.

Abnormalities of the "a" Wave

The "a" wave in theJVP is absent when there is no effective atrial contraction, such as in atrial fibrillation( figure 203-e ). In certain other conditions, the "a" wave may not be apparent. In sinus tachycardia the "a" wave may fuse with the preceding "v" wave, particularly if the PR interval is prolonged. In some patients with sinus tachycardia, the "a"wave may occur during the "v" or "y" descent and may be small or absent. In the presence of first-degree AV block, a discreet "a" wave with ascending and descending limbs is often completed prior to the first heart sound and the ac interval is prolonged( figure 203-f).

Large "a" waves are of considerable diagnostic value (figure 203-b ). When giant "a" waves are present with each beat,the right atrium is contracting against an increased resistance. This may result from obstruction at the tricuspid valve( tricuspid stenosis or atresia,right atrial myxoma or conditions associated with increased resistance to right ventricular filling. A giant "a" wave is more likely to occur in patients with pulmonary stenosis or pulmonary hypertension in whom both the atrial and right ventricular septa are intact. Cannon "a" waves occur when the right atrium contracts while the tricuspid valve is closed during right ventricular systole. Cannon waves may occur either regularly or irregularly and are most common in the presence of arrhythmias (figure 203-g ).

Abnormalities of the "x" Wave

The most important alteration of the normally negative systolic collapse("x" wave) of the JCP is its obliteration or even replacement by a positive wave. This is usually due to tricuspid regurgitation. Although atrial relaxation may contribute to the normal "x"descent ,the development of atrial fibrillation does not obliterate the "x" wave except in the presence of tricuspid regurgitation. Accordingly, the occurrence of a positive wave the JVP during ventricular systole is strong evidence of tricuspid regurgitation (figures 203-a and 204). mild tricuspid regurgitation lessens and shortens the downward "x" wave as the regurgitation of blood into the right atrium produces a positive wave that diminishes the usual systolic fall in venous pressure. In some patients with moderate tricuspid regurgitation, there is a fairly distinct positive wave during the ventricular systole between the "c" and "v" waves. This abnormal systolic waveform is usually referred to as a "v" or "cv" wave, although it has also been referred to as "r "(regurgitant) or an "s"(systolic) wave. In patients with constricted pericarditis the "x" descent wave during systole is often more prominent than the early diastolic "y" a wave (figure203-c ).

Figure 204: Right ventricular (RV) and right atrial (RA) pressure curves and simultaneous ECG form a patient with severe tricuspid regurgitation. Note vdntricularization of the RA pressure curve.


Abnormalities of the "v" Wave

The positive, late systolic "v" wave results from the increasing right atrial blood volume during ventricular systole when the tricuspid valve normally is closed. With mild tricuspid regurgitation, the "v" wave becomes more prominent, and when tricuspid regurgitation becomes severe, the prominent "v" wave and the obliteration of the "x" descent results in a single, large positive systolic wave (ventricularization) ( figures203-a and 204 ). Normally the "v" wave is lower in amplitude than the "a" wave in the JVP. In patients with an atrial septal defect, however, the higher left atrial pressure is transmitted to the right atrium and the "a" and "v" waves are often equal in the right atrium and the JVP (figure 203-d). In patients with constrictive pericarditis and sinus rhythm the right atrial "a" and "v" waves may also be equal, but the venous pressure is increased, which is unusual with isolated atrial septal defect. In patients with constrictive pericarditis who are in atrila fibrillation, the "cv" wave is prominent and the "y"descent rapid .

Abormalities of the "y" Trough

The "y" descent , or diastolic collapse, is usually is produced mainly by the tricuspid valve opening and the rapid inflow of blood into the right ventricle. A rapid deep "y" descent in in early diastole occurs with severe tricuspid regurgitation (figure 203-a blank).A venous pulse characterized by a sharp "y" trough, and a rapid ascent to the baseline is seen in patients with constrictive pericarditis or with severe right -sided heart failure. A slow "y" descent in the JVP suggests an obstruction to right ventricular filling and may be the only abnormal finding in patients with tricuspid stenosis or right atrial myxoma (figure203-b). In both constrictive pericarditis and severe right-sided heart failure, the venous pressure is elevated with a sharp "y "dip in the JPD. The presence of a large positive systolic venous wave favors the diagnosis of severe heart failure.

Effects of Arrhythmias of the Venous Pulse

The large "a" waves in the JVP during arrhythmias are present when the P wave (atrial contraction) occurs between the onset of the QRS complex and determination of the T wave (figure 203-g ). Such cannon "a" waves may occur regularly in junctional rhythm. More commonly, they occur irregularly when AV dissociation accompanies premature ventricular contractions, ventricular tachycardia, or complete heart block. The "a" wave is absent in patients with atrial fibrillation, and flutter "a" waves at a regular rate of 250 to 300 per minute frequently are observed in patients with atrial flutter and varying degrees of AV block. Patients with multifocal atrial tachycardia often have prominent and somewhat variable "a" waves in the JCP. In these patients, many of whom have pulmonary hypertension secondary to lung disease, the "a" waves are often very large.

Reference:O'Rourke,R.A.and Others,General Examination of the Patient,Hurst's, The Heart,Eighth Edition,Pp.238-242.