Jugular Venous Pulse

A, C and V waves of JVP occur secondary to pressure changes in the atria which are transmitted to the great veins.

The c wave is the transmitted manifestation of the rise in atrial pressure produced by the bulging of the tricuspid valve into the atria during isovolumetric ventricular contraction.

Ref: Ganong’s Review of Medical Physiology, 23rd Edition, Chapter 31

B i.e. Prominent X descent with absent ‘Y’ descent

Answer is A (Cannon waves in complete heart block)

Cannon a waves are large ‘a’ waves that may be seen in complete heart block.

• Cannon waves are large ‘a’ waves. They may be seen in complete heart block.
• Slow v-y descent in the JVP suggests an obstruction to right ventricular filling, as occurs with Tricuspid Stenosis or Right Atrial Myxoma.
• Tricuspid Regurgitation causes the v-waves to be prominent, when TR becomes severe, the combination of a prominent v-wave and obliteration of x-descent results in a single large positive systolic wave.
• Tricuspid stenosis is associated with large/giant ‘a’ waves and not large/giant c waves.  Tricuspid stenosis- Positive presystolic a-wave is enlarged when the right atrium is contracting against an increased resistance.
• SVC obstruction causes raised JVP with absent pulsation 

Answer is C (Tricuspid Regurgitation)

Tricuspid stenosis (not Tricuspid regurgitation) is associated with large or ‘a’ giant waves.

`a’ waves in JVP:

Are positive waves, due to distension produced by Right atrial contraction. Large ‘a’ waves indicate atrium is contracting against increased resistance.

Large ‘a’ waves :

• Tricuspid stenosis 
• Pulmonary stenosis 
• Pulmonary hypertension

Cannon ‘a’ waves :

• Regularly

– During junctional rhythm 

• Irregularly

– Atrioventricular dissociation with ventricular tachycardia

– Complete heart block 

Absent `a’ waves :

Atrial fibrillation 

Answer is A (Absent Y descent)

Cardiac tamponade is charachterized by jugular venous distension (1^‘ ed JVP) with a prominent X descent but an, absent Y descent – Harrisons 

Ans. B: Atrial contraction

Waves

* a – presystolic; produced by right atrial contraction

* c – bulging of tricuspid valve into the right atrium during ventricular systole (isovolumic phase)

* v – occurs in late ventricular systole; increased blood in right atrium from venous return

Descents

*  x – combination of atrial relaxation, downward movement of the tricuspid valve and ventricular systole

* y – tricuspid valve opens and blood flows in to the right ventricle 

Abnormal waveform causes

Dominant a wave

* Pulmonary stenosis

* Pulmonary hypertension

* Tricuspid stenosis

Cannon a wave

* Complete heart block

* Paroxysmal nodal tachycardia

Ventricular tachycardia

* Dominant v wave

* Tricuspid regurgitation

 * Absent x descent

* Atrial fibrillation

* Exaggerated x descent

* Cardiac tamponade

* Constrictive pericarditis

* Sharp y descent

* Constrictive pericarditis

* Tricuspid regurgitation

* Slow y descent

* Right atrial myxoma

Ans. is A

The first elevation (a wave) corresponds to the slight rise in atrial pressure resulting from atrial contraction.

The first descent (x descent) reflects a fall in atrial pressure that starts with atrial relaxation.

The second elevation (v wave) corresponds to ventricular systole when blood is entering the right atrium from the vena cavae while the tricuspid valve is closed.

Finally, the second descent (y descent) reflects falling right atrial pressure as the tricuspid valve opens and blood drains from the atrium into the ventricle.