<prompt> In JVP, a- wave is due to:Atrial relaxationAtrial fillingAtrial contractionVentricular relaxation  <response>: Ans. C Atrial contractionRef: Harrisons Internal Medicine, 17th ed. Chapter 220, PE of CVS.NORMAL JVP WAVEFORM Classically three upward deflections and two downward deflections have been described. The a wave corresponds to right Atrial contraction and ends synchronously with the carotid artery pulse. The peak of the a wave demarcates the end of atrial systole. The c wave corresponds to right ventricular contractioncausing the tricuspid valve to bulge towards the right atrium. The x descent follows the a wave and corresponds to atrial relaxation and rapid atrial filling due to low pressure. The x x prime descent follows the c wave and occurs as a result of the right ventricle pulling the tricuspid valve downward during ventricular systole. The v wave corresponds to venous filling when the tricuspid valve is closed and venous pressure increases from venous return - this occurs during and following the carotid pulse. The y descent corresponds to the rapid emptying of the atrium into the ventricle following the opening of the tricuspid valve.Extra MileAbout JVPRaised JVP, Normal waveformRaised JVP, absent pulsation:Large a wave increased atrial contraction pressureBradycardia Fluid overload Heart FailureSuperior vena cava syndrome Cardiac TamponadeTricuspid stenosis Right heart failure Pulmonary hypertensionCannon a wave atria contracting against closed tricuspid valveAbsent a wave no unifocal atrialdepolarizationParadoxical JVP Kussmauls sign: JVP rises with inspiration, drops with expirationAtrial flutter Premature atrial rhythm or tachycardiaThird degree heart blockVentricular ectopicsVentriculartachycardiaAtrial fibrillationPericardialeffusionConstrictivepericarditisPericardialtamponade Large v wave c-v wave: Tricuspid regurgitation Slow y descent: Tricuspid stenosis 