Understanding JVP Waves: Absent A Wave in Atrial Fibrillation Neet PG/FMGE

Jugular Venous Pulse (JVP) reflects the pressure changes occurring in the right atrium during the cardiac cycle.

Understanding JVP waveforms is essential for diagnosing rhythm disorders like atrial fibrillation.

Question
An alcoholic patient presents with:
• Palpitations
• Dizziness
• Syncopal attacks
On examination, an irregularly irregular pulse is noted.
What will be seen on JVP?

Options:
• Absent a wave
• Large a wave
• Cannon a wave
• Steep y descent

Correct Option: Absent a wave

Explanation
The irregularly irregular pulse suggests atrial fibrillation.

In atrial fibrillation:

• There is no coordinated atrial systole

• Atrial muscle fibers contract chaotically
• As a result, effective atrial contraction is lost

Since the a wave of JVP corresponds to atrial contraction, the absence of organized atrial contraction leads to absence of a wave in JVP.
Jugular Venous Pulse (JVP) Waves
JVP reflects right atrial pressure changes during the cardiac cycle.

JVP Waveform Diagram

Positive waves in JVP

• a wave – atrial contraction (late rapid filling phase)
• c wave – tricuspid valve bulging toward atrium
• v wave – venous return

Negative waves in JVP

• x descent – atrial relaxation
• x′ descent – downward displacement of tricuspid valve during ventricular systole
• y descent – opening of tricuspid valve

JVP Findings and Causes

JVP FindingCauseAbsent a waveAtrial fibrillationLarge a waveTricuspid stenosis, pulmonary hypertensionCannon a waveComplete heart block, ventricular tachycardiaSteep y descentConstrictive pericarditis

Why A Wave Is Absent in Atrial Fibrillation

• A wave is produced by atrial contraction
• In atrial fibrillation, atria do not contract in a coordinated manner
• Hence, a wave disappears from JVP
ECG Findings in Atrial Fibrillation
• Irregularly irregular RR intervals
• Absent P waves
• Fibrillatory baseline

Causes of Atrial Fibrillation

• Hypertension
• Valvular heart disease (especially mitral)
• Alcohol (holiday heart syndrome)
• Thyrotoxicosis

Complications of Atrial Fibrillation

• Stroke
• Heart failure
• Tachycardia-induced cardiomyopathy

Management of Atrial Fibrillation

• Rate control (β-blockers, calcium channel blockers)
• Rhythm control (amiodarone, cardioversion)
• Anticoagulation based on CHA₂DS₂-VASc score.

Conclusion
In atrial fibrillation, the loss of organized atrial contraction leads to absence of a wave in JVP.
This finding directly reflects the underlying pathophysiology of the arrhythmia.