# Jugular Venous Pulse Waveform > Jugular venous pulse waveform for NEET-PG Medicine covering a, c and v waves, x and y descents, cannon a waves and the Kussmaul sign at the bedside. - Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/jugular-venous-pulse-waveform - Exam / course: NEET-PG · Subject: Medicine - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-08 - Last updated: 2026-10-08 - Reference basis: Bates' Guide to Physical Examination and History-Taking; Talley and O'Connor's Clinical Examination; Hutchison's Clinical Methods - How to cite: "Jugular Venous Pulse Waveform", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/jugular-venous-pulse-waveform ## 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. 1. **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. 2. **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. 3. **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. 4. **Check for atrial fibrillation:** If atrial fibrillation were present, the a waves would be absent, and that would be a useful check. 5. **Look for cannon waves:** A cannon a wave, large and irregular with a varying first heart sound, suggests atrioventricular dissociation. 6. **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. 7. **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.