Noninvasive assessment of mitral inertness: clinical results with numerical model validation

Inertial forces (Mdv/dt) are a significant component of transmitral flow, but cannot be measured with Doppler echo. We validated a method of estimating Mdv/dt. Ten patients had a dual-sensor transmitral (TM) catheter placed during cardiac surgery. Doppler and 2D echo measurements were performed while acquiring left-atrial (LA) and left-ventricular (LV) pressures. Mdv/dt was determined from the Bernoulli equation using Doppler velocities and TM gradients. The results were compared with numerical modeling. The TM gradients (range: 1.04-14.24 mmHg) consisted of 74.0±11.0% inertial forcers (range: 0.6-12.9 mmHg). Multivariate analysis predicted Mdv/dt = -4.171(S/D) + 0.063(LA_VOLUME-MAX) + 5, where S/D is the systolic/diastolic ratio. Using this equation, a strong relationship was obtained between the clinical data set (y = 0.98x - 0.045, r=0.90) and the results of the numerical modeling (y = 0.96x - 0.16, r=0.84). TM gradients are mainly inertial and, as validated by modeling, can be estimated with echocardiography