PHT serve para estimar a área valvar após reparo cirúrgico? - by Fábio Soares

A complacência ventricular (idosos, HAS grave, EAo grave), taquicardia, insuficiência aórtica (maior que leve), valvotomia percutânea ou cirúrgia e valvoplastia cirúrgica influenciam diretamente a medida da área valvar por PHT. Mesmo em próteses valvares este método apresenta limitações.

 - Chambers J, Jackson G, Jewitt D. Limitations of Doppler ultrasound in the assessment of the function of prosthetic mitral valves. Heart 1990;63:189–94.

- A inadequação do PHT provavelmente é devido ao fato de que este método é mais dependente de outras variáveis que a própria área valvar (assim como ocorre com as próteses valvares, é provável que o mesmo se aplique às valvas submetidas a plastia)

 - Chambers J, McLoughlin N, Rapson A, Jackson G. Effect of changes in heart rate on pressure half-time in normally functioning mitral valve prostheses. Br Heart J 1988;60:502–6.

Aims Pressure half-time is an inaccurate measure of mitral valve area in many clinical situations. The utility of the pressure half-time method to calculate mitral valve area after mitral valve repair is not well defined.

Methods and results Forty-two patients with a repaired mitral valve were identified. Mitral valve area was calculated by both the pressure half-time method and the continuity equation. The two mitral valve areas were then directly compared and also correlated with mean gradient. The two mitral valve areas were significantly different from one another with a mean of 1.81+0.53 cm2 by continuity equation and 2.65+0.69 cm2 by pressure half-time. The continuity equation correlated well with mean gradient (r ¼ 20.63), whereas the correlation for pressure half-time was weak (r ¼ 20.08).

Conclusion A non-linear, inverse correlation was found between mitral valve area by the continuity equation and mean gradient. No correlation was found between the pressure half-time method for mitral valve area and mean gradient. The continuity equation likely provides a better estimate of mitral valve area in repaired mitral valves.