Estimation of pulmonary capillary wedge pressure in heart transplants-A new application for Doppler tissue imaging

To date, right heart catheterization (RHC) is the only available method for measuring left ventricular filling pressures in heart transplants, given the unreliable results obtained thus far with the current Doppler methods. Doppler tissue imaging (DTI) is a new technique that permits the evaluation of myocardial relaxation, thus allowing correction for the influence of relaxation on peak early mitral flow velocity (E) Accordingly, we prospectively evaluated 22 patients (20 males) with simultaneous RHC and Doppler echocardiography. Their mean age was 53±17 and their left ventricular ejection fraction was 55±12.6 (23% to 67%). The transmitral flow and isovolumetric relaxation time (IVRT) were combined with recordings of early (Em) and late (Am) myocardial relaxation velocities obtained at the lateral border of the mitral annulus by DTI. Measurements were averaged over 5 cycles. Mean pulmonary capillary wedge pressure (PCWP) ranged between 5 and 26 mm Hg (14±6.5) Weak but significant correlations were observed between PCWP and mitral inflow variables (-0.5 for A to 0.6 for E/A) and IVRT (-0.45). No significant correlations were seen between PCWP and Em or Am. The ratio E/Em related strongly with PCWP (r=0.75, p<0.0001) and provided a good estimate of the pressure (PCWP=2.25+1.5[E/Em)). The mean difference between Doppler and catheter PCWP was 0.4±4.1 mm Hg. We conclude that PCWP can be accurately estimated in cardiac transplants using the ratio of transmitral E velocity to early myocardial relaxation velocity acquired by Doppler tissue imaging.