Chapter 4 / Jugular Venous Pulse 67 4 Jugular Venous Pulse CONTENTS NORMAL RIGHT ATRIAL PRESSURE PULSE CONTOURS JUGULAR VENOUS INFLOW VELOCITY PATTERNS AND THE RELATIONSHIP TO THE RIGHT ATRIAL PRESSURE PULSE JUGULAR VENOUS FLOW EVENTS AND THEIR RELATIONSHIP TO JUGULAR VENOUS PULSE CONTOURS NORMAL JUGULAR VENOUS PULSE CONTOUR AND ITS RECOGNITION AT THE BEDSIDE INDIVIDUAL COMPONENTS OF THE RIGHT ATRIAL PRESSURE PULSE, THEIR DETERMINANTS, AND THEIR RECOGNITION IN THE JUGULARS ABNORMAL JUGULAR VENOUS PULSE CONTOURS AS RELATED TO ABNORMAL JUGULAR VENOUS FLOW VELOCITY PATTERNS ABNORMAL JUGULAR CONTOURS ASSESSMENT OF JUGULAR VENOUS PRESSURE CLINICAL ASSESSMENT OF THE JUGULAR VENOUS PULSE REFERENCES The physiology of the normal jugular venous pulse contours and the pathophysiology of their alterations will be discussed in this chapter. Mechanisms of venous return and right heart filling have been of clinical interest from the days of Harvey and Purkinje (1,2). Long before Chauveau and Marey published their recordings of the venous pulse, Lancisi had described “the systolic fluctuation of the external jugular vein” in a patient with tricuspid regurgitation (3,4). Potain demonstrated the presystolic timing of the dominant wave of the normal venous pulse by simultaneous recording of the venous and the carotid artery pulses (5). In the early part of the last century, the detailed studies of the venous pulse by Mackenzie helped define the waveforms, their terminology, and their origins. He called the main waves “a,” “c,” and “v” to denote the first letters of what he thought were their anatomical sites of origins, namely the right atrium, the carotid artery, and the right ventricle. He distinguished the “ventricular type venous pulse” of tricuspid regurgitation from the “auricular type” and associated it with atrial fibrillation, demonstrating also the progression of the former from the latter over time (6,7). Since the days of Mackenzie, clinicians have studied the venous pressure and the pulse contour in different clinical conditions (8–33) The advent of cardiac catheterization, the record- ing of intracardiac pressures, and the development of techniques to study blood flow velocity all contributed substantially to our understanding of the mechanisms of venous return, right heart filling and function (10,11,13,18,20,21,24,28,30,34–46). 67 68 Cardiac Physical Examination Since right atrial pressure pulse and the venous inflow into the right heart affect the jugular contours, a good understanding of the basics of their relationship both in the normals as well as in the abnormals is very meaningful and important. The discussion will be sequential under the following headings: 1. Normal right atrial pressure pulse contours 2. Jugular venous inflow velocity patterns and the relationship to the right atrial pressure pulse 3. Jugular venous flow events and their relationship to jugular venous pulse contours 4. Normal jugular venous pulse contour and its recognition at the bedside 5. Individual components of the right atrial pressure pulse, their determinants and their recognition in the jugulars 6. Abnormal jugular venous pulse contours as related to abnormal jugular venous flow velocity patterns 7. Mechanism of abnormal jugular venous flow velocity patterns and contours in pulmo- nary hypertension 8. Mechanism of abnormal jugular venous flow patterns and contours in post-cardiac- surgery patients 9. Mechanism of abnormal jugular venous flow patterns and contours in restriction to ventricular filling 10. Abnormal jugular contours 11. Assessment of jugular venous pressure 12. Clinical assessment of the jugular venous pulse NORMAL RIGHT ATRIAL PRESSURE PULSE CONTOURS The sequential changes in right atrial (RA) pressure during the cardiac cycle can be considered starting with the beginning of diastole. In diastole when the tricuspid valve opens, the atrium begins to empty into the right ventricle (RV). The diastolic filling of the ventricle consists of three consecutive phases: 1. Early rapid filling phase when the ventricular pressure, which has fallen quite low, com- pared to that in the atrium (often close to 0 mmHg) begins to rise with the rapid tricuspid inflow. 2. The slow filling phase follows the early rapid filling phase when the inflow velocity begins to slow down. During this phase the ventricular pressure actually begins to equalize with that of the atrium. The pressure where this equalization occurs is deter- mined by the compliance of the RV and the surrounding pericardium and thorax. In normal subjects the pressure during this phase is usually less than 5 mmHg. It can also be termed the pre-a wave pressure since this phase is immediately followed by atrial contraction. The pre-a wave pressure is also the baseline filling pressure over which pressure wave buildup can occur in the atrium at other periods of the cardiac cycle. 3. The last phase of ventricular filling occurs at the end of diastole during the atrial con- traction, which raises the pressure in the atrium. The ventricular pressure follows the atrial pressure because the tricuspid valve is still open. The level to which the pressure might rise during atrial contraction (a wave pressure, named after atrial systole) would depend on the strength of the atrial contraction as well as the baseline pre-a wave pressure and the right ventricular distensibility (compliance). Atrial contraction is followed not only by atrial relaxation but also by ventricular contraction. Both events follow each other in succession during normal atrioventricular (A-V) electrical conduction (during normal PR relationship). Both events lead to a fall Chapter 4 / Jugular Venous Pulse 69 in atrial pressure. The fall caused by atrial relaxation completes the a wave and is termed the x descent. During ventricular contraction, which follows atrial contraction, the ventricular pres- sure rises, and once it exceeds the pressure in the atrium, the tricuspid valve becomes closed. As ventricular systole continues, RV pressure rises, and once it exceeds the pulmonary diastolic pressure, the pulmonary valve opens and ejection of blood into the pulmonary artery occurs. During this phase of ventricular systole, however, the atrial pressure continues to fall. This fall in atrial pressure is termed the x′ descent. This should be distinguished from the x descent caused by atrial relaxation (26). The x′ descent, on the other hand, is caused by the descent of the base of the ventricle. The contracting RV actually pulls the closed tricuspid valve and the tricuspid ring, which together form the floor of the atrium (34,37,39,46). This movement of the base can be easily observed when one views a cine-angiogram of the right coronary artery. The right coronary artery runs along the right A-V groove, and it can be seen to move down with each ventricular systole. Similar motion of the descent of the base can also be seen on the left side in relationship to the circumflex coronary artery, which runs along the left ventricular (LV) side of the A-V groove. The descent of the base of the ventricles can be also appreciated during ventricular systole in the four chamber views of the two-dimensional echocardio- grams. The representation on the image display screen however, is usually such that the apex of the heart is at the top. Careful observation will clearly show that the A-V ring with the closed tricuspid and mitral valves moves during systole towards the ventricular side, actually causing an expansion of the atrial area and dimension. The descent of the base is particularly important for the RV for its ejection, since the interventricular sep- tum actually moves with the left ventricle during systole, as will be readily observed in the two-dimensional echo image of the left ventricle in the long axis view as well as the short axis view (see Normal Subject image file in Jugular Venous Pulse, Normal on the Companion CD). The drop in atrial pressure during ventricular systole may be facilitated by the fall in pericardial pressures that occurs when the volume of the heart decreases during systole (27). The preservation of the x′ descent in atrial standstill and atrial fibrillation further supports the concept that the x′ descent is unrelated to atrial relaxation (28,40,47). The x′ descent, on the other hand, requires not only normal RV contraction but also an intact tricuspid valve. Towards the later phase of systole when the ventricle has completed most of its ejection, the pull on the closed tricuspid valve and ring decreases. The venous inflow into RA from the vena cavae now is able to overcome the fall in atrial pressure caused by the descent of the base. This helps to build up the atrial pressure to a peak of the next wave, termed the v wave. The v wave is therefore the venous filling wave in the atrium (named originally after ventricular systole). It occurs during a later phase of ventricular systole. The level to which the v wave pressure can be built up in the presence of an intact tricuspid valve depends not only on the right atrial distensibility or compliance, but also on the baseline filling pressure, which is the pre- a-wave pressure. Occasionally one can recognize a break point on the atrial pressure curve between the x and the x′ descent. This point may sometimes be termed the c point because it roughly corresponds in timing to the tricuspid valve closure. Reference to the so-called c waves is made occasionally in relation to humps seen between the a and the v waves in the 70 Cardiac Physical Examination Fig. 1. Simultaneous recordings of electrocardiogram (ECG), jugular venous flow (JVF) velocity recording, right atrial (RA), and right ventricular (RV) pressures in a subject with normal right heart hemodynamics. The RA pressure curve shows the a and the v waves with x′ descent > y descent.