Left atrial and right atrial pressure in MR

A transseptal catheter is in the left atrium (LA) and the pressure tracing shows large "v" waves as a result of mitral regurgitation (MR). The "v" wave of 40 mmHg is twice the mean LA pressure which is 20 mmHg. The asterisk shows where the catheter is pulled back to the right atrium (RA); since the pressure tracing is continuous, it accurately reflects the pressure gradient between the LA and RA. The RA pressure is lower, and the a and v waves are diminutive relative to the left side.