<prompt> A wave in JVP is absent in:Atrial fibrillationHeart blockTricuspid regurgitationComplete heart block  <response>: Ans. a Atrial fibrillationRef: Harrison 19th ed. 1443-1444 A wave in JVP is due to atrial contraction. In atrial fibrillation, since the atria are twitching, the power of atria is reduced to a level that a wave would be absent. Heart block will have large a waves. Tricuspid Regurgitation has absent x and large v waves. Constrictive Pericarditis has a large y descent. 