Introduction

Running along the sternocleidomastoid muscle, the internal jugular vein (IJV) provides deoxygenated blood directly to the right atrium. Although there is a functional valve bordering the superior vena cava (SVC) and right atrium, this valve does not appear to hinder the phasic flow of blood to the right atrium. Therefore, the pulsations that can be observed at the level of the IJV can provide valuable insight into the hemodynamics of blood at the right atrium level.[1] The relationship between the IJV and the right atrium is important because it provides healthcare professionals with an invaluable physical examination tool. The bedside jugular venous pulse (JVP) examination can determine the central venous pressure (CVP), venous pulse contour, and many cardiac pathologies.[2]

Issues of Concern

The examination of the JVP is a frequently overlooked physical examination technique due to the plethora of advancing technologies.[3] However, healthcare practitioners must understand this examination because it is not only resourceful but also diagnostically valuable and can be easily repeatable.[3]

Function

The JVP tracing measures the right atrial pressure (RAP) that can provide a patient’s intravascular volume status. The JVP tracing can be obtained by inserting a central line into the superior vena cava or, less invasively, can be observed from the bedside.[4] At the bedside, the JVP is often observed at the right side of the patient’s neck, more specifically it can be seen passing diagonally over the top of the sternocleidomastoid muscle. Next, once the patient is in a comfortable reclined position, a penlight can be pointed at a 45-degree angle toward the midline of the neck. The examiner should now be able to observe and measure the venous pulsations. The height of the JVP can be measured by intersecting 2 rulers perpendicularly, 1 ruler extending horizontally from the observed JVP, and the other ruler extending vertically from the sternal angle of Louis.[5][6] The distance from the sternal angle to the intersection is then measured. Finally, the height of JVP is calculated by adding the distance measured plus the constant distance from the midpoint of the right atrium to the sternal angle (5 cm HO).[7][8] The midpoint of the right atrium is added because the JVP is defined as the vertical distance above this point. Normally, the JVP is between 6 to 8 cm H₂O.

Mechanism

The tracings of the jugular venous pulse wave, which can be observed using cardiac catheterization, are said to be biphasic due to the presence of alternating peaks and troughs.[1][9] The tracing begins with an "A" wave peak that corresponds to the contracting right atrium (atrial systole), next there is a "C" wave peak that represents the contracting right ventricle (ventricular systole) causing the tricuspid valve to bulge towards the right atrium during RV isovolumetric contraction. Following the “C” wave there is an "X" (X prime) descent result of the right ventricle pulling the tricuspid valve downward during ventricular systole.[10] Additionally, there is also an “X” descent that follows the "A" wave which represents atrial relaxation and the resulting rapid atrial filling that ensues (atrial systole).[11] The "V" wave represents venous filling when the tricuspid valve is closed and venous pressure increases from venous return. Finally, as the tricuspid valve opens and the blood in the right atrium empties into the right ventricle (ventricular diastole), this is the final trough, known as the “Y descent” on the pressure tracing.[11]

Pathophysiology

The first peak observed in a normal jugular venous pulse wave tracing, the "A" wave, represents the contraction of the atria (atrial systole). Therefore, in patients with atrial fibrillation, the "A" wave is often attenuated due to the absence of atrial contraction.[10][11][12] Furthermore, the absence of contraction in atrial fibrillation additionally means atrial relaxation must also not be occurring, causing an attenuation of the "X" descent.[12] On the contrary, the "A" wave can be more pronounced, and the "Y" descent can be slightly attenuated when there is an increased resistance of blood flow traveling through the right atrium. Increased resistance across the tricuspid valve is often seen in patients with pulmonary hypertension, tricuspid stenosis, and pulmonic stenosis.[13][14][15][16][17]

The chronological sequence of the atria contracting before the ventricles is important for the shuttling of blood through the circulatory system. When this sequence becomes asynchronous, such as what is seen with third-degree atrioventricular heart block, this can cause the atria and ventricles to contract at the same time.[18][19][1] This can, unfortunately, prevent the shuttling of blood through the tricuspid valve due to the force of ventricular contraction. As a result, the easily discernible "Cannon A wave" can be seen on the jugular venous pulse wave tracing and even on physical exam.[20][21]

Tricuspid regurgitation occurs during systole, as a portion of blood is inadvertently sent back to the atrium through an incompetent tricuspid valve, rather than through the pulmonary arteries.[22] This is also quite noticeable in pulse tracings, as there can be a very prominent attenuation of the "X" descent or even the formation of a "CV" wave. A "CV" wave, which occurs when the "X" descent diminishes, can be observed in severe cases of tricuspid regurgitation.[20][23]

The "Y" descent can also be significantly attenuated because of the inability of the right atrium to relax during ventricular diastole.[24] The fixed perimeter of the fluid-filled pericardial sac results in increased pressure on the right atrium during its emptying of blood into the right ventricle. Although there is blood leaving the atrium potentially relieving pressure on the atrium, this relief is immediately negated by the pressure from the upward shift of fluid within the pericardial sac as a result of the expansion of the right ventricle.[25][26][27] This phenomenon is known as cardiac tamponade. Cardiac tamponade can be characterized on a JVP tracing as a severely attenuated or absent "Y" descent. On the contrary, one can observe a very prominent "Y descent' (Friedreich's sign) with constrictive pericarditis due to the limited ability of the right ventricle to expand during ventricular diastole.[28][29]

Clinical Significance

A critical bedside examination of the JVP provides invaluable information relating to disease processes and medication management. Using the method above to examine the height of the JVP, clinicians are able to interpret the volume status of patients. Simply stated, an elevated JVP of greater than 9 cm H₂O (venous hypertension) along with other symptoms can help distinguish between left and right heart failure, suggest pericardial disease, and suggest some specific types of arrhythmias.[4] Conversely, a low JVP of less than 5 cm H₂O can reflect either hypovolemia or the use of diuretics. The JVP assessment used alongside other diagnostic cardiac testing can help the clinician to make the proper diagnosis and guide treatment decisions.[4]