Introduction
The jugular venous pressure (JVP) refers to the pressure in the internal jugular veins. The height of the JVP reflects right heart pressure and function.
Practicalities of interpretation
Patients should be positioned at 45° to the horizontal when measuring the JVP. The JVP is easiest to observe along the sternocleidomastoid muscle.
Filling of the internal jugular 3 cm or higher above the angle Louis (sternal angle) is considered as elevated JVP.
Differences from carotid pulse
The JVP can be confused with the carotid pulse. Clinical features of the JVP include:
- Non-palpable
- Readily occludable – pressing on the vessel should stop the JVP. It can be observed that the vein fills from above
- Multiphasic – the JVP has 2 peaks for every heartbeat
- Decreases with respiration – inspiration decreases thoracic pressure, leading to increased venous return to the right heart and the pulmonary circulation
JVP waveforms
The waveforms of the JVP can be observed in invasive central venous pressure (CVP) monitoring. Changes in JVP waveforms may suggest pathology. Normal waveforms include:
a wave: atrial contraction
c wave: ventricular contraction
x descent: atrial relaxation
v wave: atrial venous filling (against close tricuspid valve)
y descent: tricuspid valve opening
Abnormal JVP waveforms
Absent a waves
Cause: Atrial fibrillation
Cannon a waves
Cannon a waves occur when the atria and ventricle contract simultaneously, producing a greatly elevated a wave.
Causes:
- Complete heart block
- Ventricular tachycardias
Large a wave
Causes:
- Tricuspid stenosis
- Pulmonary stenosis
- Pulmonary hypertension
Constrictive pericarditis vs Tamponade
The main method of differentiating tamponade from constrictive pericarditis on JVP is by observing the x and y descent. Tamponades produce sharp x descent only, whilst constrictive pericarditis produces sharp x and y descent.
Constrictive pericarditis
JVP features:
- Sharp x and y descent
- Large v wave
Tamponade
JVP features:
- Sharp x descent only
- Large v wave
Abnormal JVP height
Elevated JVP with normal waves
Causes:
- Fluid overload
- Heart failure
Elevated JVP with no waves present
Cause: Superior vena cava obstruction
Absent JVP
Cause: Hypovolaemia
Kussmaul’s sign
Normally, the JVP should go down with inspiration as a result of the drop in intrathoracic pressure. Kussmaul’s sign is an abnormal finding that refers to the JVP paradoxically rising with inspiration. It is seen in conditions affecting right heart function. During inspiration in right heart dysfunction, there is an increase in venous return but the heart cannot effectively pump it through the pulmonary circulation, leading to JVP elevation.
Causes:
- Tamponade
- Constrictive pericarditis
- Right heart failure
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