Q. Explain Atrial Pressure?

The RA pressure wave form has three positive deflections - "a", "c", and "v" waves. The "a" wave is due to atrial systole and follows the P-wave on surface ECG. The "x" descent follows the "a" wave and represents atrial relaxation and downward pulling of the tricuspid annulus by RV contraction. The "x" descent is interrupted by the "c" wave, which is a small positive deflection caused by protrusion of the closed tricuspid valve into the RA. The pressure in the RA rises after the "x" descent due to passive atrial filling. The atrial pressure then peaks as the "v" which represents ventricular systole.

The LA pressure waveform is similar to that of the RA although normal LA pressure is higher representing the high pressure system of the left side of the heart. In LA pressures, unlike RA pressures, the "v" wave is generally higher than the "a" wave.