Effect of respiration on Doppler parameters of normal tricuspid porcine bioprosthetic valves

Abstract

The Doppler indexes of tricuspid porcine bioprosthetic valves were evaluated in twelve patients without clinical and two-dimensional echocardiographic evidence of valve dysfunction. Peak and mean pressure gradients across the prostheses were measured using the simplified Bernoulli equation. All the Doppler measurements were compared during inspiration and expiration. During inspiration peak velocity, peak gradient and mean gradient (1.52 ± 0.28 m/s; 9.7 ± 3.05 mmHg; 4.07 ± 1.16 mmHg) were significantly higher than during expiration (1.28 ± 0.8 m/s; 6.58 ± 2.7 mmHg; 2.98 ± 1.13 mmHg; p < 0.01) but pressure half time was not significantly different (122 ± 62 ms versus 134 ± 75 ms; p > 0.05). Inspiratory range of peak velocities, peak gradients, mean gradients and pressure half times were respectively 0.8–2.04 m/s; 4.9–16.6 mmHg; 1.2–7.2 mmHg; 42–340 ms while expiratory range of values was 0.8–1.93 m/s; 2.6–15 mmHg; 1.1–5.7 mmHg; 46–345 ms. These data suggest that even very long pressure half times do not indicate valve dysfunction. This study demonstrates that large variation of Doppler parameters are present during respiration and could produce inaccuracy in the assessment of bioprostheses in tricuspid position if they are not taken in consideration.