Echocardiographic vs Invasive Measurement of the Direct Flow Transcatheter Aortic Heart Valve Mean Gradient: Contradictory or Complementary?

In this case report, we explain the reason behind observed differences in echocardiographic and invasively measured mean aortic valve gradient after transcatheter aortic valve implantation. A 25-mm Direct Flow valve (Direct Flow Medical Inc, Santa Rosa, CA) was successfully implanted in a patient with severe aortic stenosis via the transfemoral route. The discrepancy between invasive and echocardiographic measurements could be explained by the combination of a non-flat velocity profile inside the tubular structure of the Direct Flow valve, which can cause local low pressure fields that result in true high gradients detected using Doppler, and pressure recovery.