'Y' descent of the IVP is due to:

(Opening of the tricuspid valve): Ref: 1306-H, 569-G (1384-HI7th) (512- Ganong 23rd)Jugular venous pulse: (JVP)* Positive presystole 'a wave' is produced by venous distension due to right atrial contraction and is the dominant wave in the JVP.* Large 'a wave' indicates that the right atrium is contracting against an increased resistance (Tricuspid stenosis, pulmonary hypertension or PS)* Large 'a-wave' also occurs during arrhythmias whenever the right atrium contracts while the tricuspid valve is closed by right ventricular systole.* C-wave - produced by the bulging of the tricuspid valve into the right atrium during right ventricular isovolumetric systole and by the impact of the carotid artery adjacent to the jugular vein* "X-descent" is due to both to atrial relaxation and to the downward displacement of the tricuspid valve during ventricular systole* "V wave" results from the increasing volume of blood in the right atrium during ventricular systole when the tricuspid valve is closed.* "Y descent" produced mainly by the opening of the tricuspid valve and the subsequent rapid inflow of blood in the right ventricles. (Tricuspid regurgitation)