• The "a" wave is due to atrial contraction
• The "c" wave is thought to be due to transmitted pulsation from the carotid arteries or to the bulging of the tricuspid valve into the right atrium. during beginning of right ventricular isovolumic systole.
• The "x" descent is due to a combination of atrial relaxation, the downward displacement of the tricuspid valve during right ventricular systole, and the ejection of blood from both the ventricles
• The "v" wave is due to the rise in atrial pressure before tricuspid opening
• The "y" descent is due to atrial emptying as blood enters the ventricle.

Also

• In atrial fibrillation no "a" wave is seen
• In tricuspid stenosis, ventricular hypertrophy (pulmonary hypertension etc >

  poorly compliant right ventricle)

  and complete heart block the "a" wave is enlarged
• In tricuspid regurgitation the "v" wave is enlarged.
• x is short and steep in cardiac tamponade