<prompt> In JVP, a wave is due to?Atrial fillingAtrial relaxationAtrial contractionVentricular relaxation  <response>: Atrial contraction REF: Harrisons Internal Medicine 17th edition Chapter 220 Physical Examination of the Cardiovascular System, venous_pressure JVP WAVEFORM: Classically three upward deflections and two downward deflections have been described. 1. The a wave corresponds to right Atrial contraction and ends synchronously with the carotid aery pulse. The peak of the a wave demarcates the end of atrial systole. 2. The c wave corresponds to right ventricular Contraction causing the triCuspid valve to bulge towards the right atrium. 3. The x descent follows the a wave and corresponds to atrial relaXation and rapid atrial filling due to low pressure. 4. 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 x x prime descent can be used as a measure of right ventricle contractility. 5. 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. 6. The y descent corresponds to the rapid emptYing of the atrium into the ventricle following the opening of the tricuspid valve. ABNORMAL JVP: 1. Raised JVP, normal waveform Bradycardia Fluid overload Hea Failure 2. Raised JVP, absent pulsation Superior vena cava syndrome 3. Large a wave increased atrial contraction pressure Tricuspid stenosis Right hea failure Pulmonary hypeension 4. Cannon a wave atria contracting against closed tricuspid valve Atrial flutter Premature atrial rhythm or tachycardia Third degree hea block Ventricular ectopics Ventricular tachycardia 5. Absent a wave no unifocal atrial depolarisation Atrial fibrillation 6. Large wave c-v wave Tricuspid regurgitation 7. Slow y descent Tricuspid stenosis 8. Parodoxical JVP Kussmauls sign: JVP rises with inspiration, drops with expiration Pericardial effusion Constrictive pericarditis Pericardial tamponade 