In JVP, "a- wave" is due to:

Ans. C Atrial contractionRef: Harrison's 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 pressure)Bradycardia Fluid overload Heart FailureSuperior vena cava syndrome Cardiac TamponadeTricuspid stenosis Right heart failure Pulmonary hypertensionCannon 'a' wave (atria contracting against closed tricuspid valve)Absent 'a' wave (no unifocal atrialdepolarization)Paradoxical JVP (Kussmaul's sign: JVP rises with inspiration, drops with expiration)Atrial flutter Premature atrial rhythm (or tachycardia)Third degree heart blockVentricular ectopicsVentriculartachycardiaAtrial fibrillationPericardialeffusionConstrictivepericarditisPericardialtamponade* Large 'v' wave (c-v wave): Tricuspid regurgitation* Slow 'y' descent: Tricuspid stenosis