V wave is one of two positive upstrokes seen in JVP. Physiological “v” wave is due to atrial filling and reaches the peak at late systole , while pathological ” v” waves are often due to tricuspid regurgitation . It is a mid systolic wave .It is a fusion of “c”and “v” waves .
Here is a patient with dilated cardiomyopathy with severe tricuspid regurgitation who presented with prominent neck veins.
there is no difficulty in identifying the v wave . Careful acuity will reveal a sharp “a” wave as well !
JVP pressure wave form of tricuspid regurgitation showing classical systolic cv waves
How to measure the amplitude of v waves ?
In JVP, there is a baseline oscillating column . Individual wave spikes occur over and above this baseline . Hence technically there should be two measurements , but we take only the top most part of the oscillating column.
What is the indirect evidence for tall v waves ?
Physiologically “y” descend is integral part of v wave (In fact , “y” descend can be referred to as down stroke of “v” wave ) .For every tall “v” wave there must be a prominent “y”descent . (Probably constrictive pericarditis is an important exception ! )
If “y” descend is not rapid but shallow one can suspect two conditions
- Tricuspid stenosis
- Significant RV dysfunction
How to differentiate v waves from a waves ?
“V” wave is a passive filling wave hence it raises slowly , has relatively shallow summit and occurs in mid or late-systole . “A”waves are due to active contraction of atria . It is a sharp pre-systolic wave . One practical way to recognise “a” wave is , it never stays in the eye , it just flickers. If your eye sees a sustained wave for more than a fraction of moment it can not be “a” wave ! Another point that may be useful is “a” is taller than “v” in right atrium .
Reference
Click below to hear the murmur of TR (Courtesy of Texas heart institute )
http://www.texasheart.org/Education/CME/explore/events/upload/HSPS13_TricuspidInsuff.mp3
Dr.S.Venkatesan MD 
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