Jugular Venous Pulse Waveform
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Direct answer
The jugular venous pulse waveform reflects right atrial pressure transmitted to the internal jugular vein, and it is read as a, c and v waves with x and y descents. The a wave is atrial contraction, the v wave is venous filling against a closed tricuspid valve, and the descents mark atrial relaxation and rapid ventricular filling. Cannon a waves, large v waves with an absent x descent, and an absent y descent identify complete heart block, tricuspid regurgitation and tamponade respectively.
What you must remember
- Measurement: the JVP is the vertical height above the sternal angle, normally no more than about 3 cm with the patient at 45 degrees.
- a wave: atrial contraction; giant a waves occur in tricuspid stenosis, pulmonary hypertension and hypertrophic cardiomyopathy, and a waves are absent in atrial fibrillation.
- Cannon a waves: atrial contraction against a closed tricuspid valve, seen in complete heart block, ventricular ectopy and junctional rhythm.
- c and v waves: the c wave reflects tricuspid valve closure and is rarely seen; the v wave is systolic filling and is giant in tricuspid regurgitation.
- x descent: atrial relaxation with downward tricuspid movement during systole; prominent in tamponade and constriction, absent in tricuspid regurgitation.
- y descent: rapid early ventricular filling; slow in tricuspid stenosis, steep in constriction and absent in tamponade.
- Kussmaul sign: a paradoxical rise of the JVP on inspiration, seen in constriction, restrictive cardiomyopathy and right ventricular infarction.
- Hepatojugular reflux: a sustained rise of the JVP on pressure over the liver suggests raised right-sided filling pressure.
Reading the neck before the chest
A 48-year-old woman with rheumatic heart disease presents with leg swelling. At the bedside her neck veins are visible at a raised angle, the pulse shows large a waves, and the y descent is slow and shallow.
- Set up the technique: The internal jugular is used, the patient sits at about 45 degrees, and the height above the sternal angle is measured.
- Time the a wave: The a wave is identified by its timing just before the first heart sound, and the carotid upstroke helps confirm the phase.
- Read the a and y waves: Large a waves suggest raised right ventricular pressure or obstructed right atrial emptying. A slow y descent indicates restricted tricuspid filling, which together point toward tricuspid stenosis.
- Check for atrial fibrillation: If atrial fibrillation were present, the a waves would be absent, and that would be a useful check.
- Look for cannon waves: A cannon a wave, large and irregular with a varying first heart sound, suggests atrioventricular dissociation.
- Separate constriction from tamponade: A prominent x descent with a steep y suggests constriction, while a prominent x descent with an absent y suggests tamponade.
- Link to auscultation: The waveform is then linked to auscultation. Tricuspid stenosis gives a mid-diastolic rumble with an opening snap, and the waveform and murmur together confirm the diagnosis before echocardiography is ordered.
Where the examiner tests the wave
The pulse is tested by timing it against the carotid pulse, and four traps recur in examiner questions.
- Trap: confusing the a and v waves Correct: the a wave falls just before the carotid upstroke and the v wave arrives near the end of systole, so timing separates them.
- Trap: misreading the cannon wave Correct: cannon a waves come from atrial contraction against a closed tricuspid valve, and the stem usually describes a varying first heart sound, which signals atrioventricular dissociation as in complete heart block.
- Trap: confusing tamponade with constriction Correct: a prominent x with an absent y in a hypotensive patient suggests tamponade, whereas prominent x and y descents with a Kussmaul sign suggest constriction, and the blood pressure or echo clue usually separates them.
- Trap: missing right heart failure in a fluid-overloaded patient Correct: a high JVP and a pulsatile liver should prompt questions about tricuspid regurgitation and right heart failure.
Frequently asked questions
What do cannon a waves indicate?
Cannon a waves occur when the atrium contracts against a closed tricuspid valve. They are most often seen in complete heart block, junctional rhythm or ventricular ectopy, and they reflect atrioventricular dissociation.
What distinguishes constrictive pericarditis from tamponade on the jugular pulse?
Constrictive pericarditis shows prominent x and y descents along with a Kussmaul sign. Tamponade shows a prominent x descent with an absent y descent, reflecting impaired right atrial filling.
What is the significance of giant a waves?
Giant a waves indicate raised right ventricular end-diastolic pressure or obstruction to right atrial emptying. They are seen in tricuspid stenosis, pulmonary hypertension and hypertrophic cardiomyopathy.
What does an absent a wave suggest?
An absent a wave is typical of atrial fibrillation, because the atria do not contract effectively. A cannon a wave should not be confused with a normal a wave when reading the pulse.
What is the hepatojugular reflux test?
Hepatojugular reflux is a sustained rise in jugular venous pressure on firm pressure over the liver. It suggests raised right-sided filling pressure, as in right heart failure.