Normal Mitral Prostheses Research Articles

987-102 Proximal Flow Convergence Calculation of Forward Flow and Valve Area of Normal Mitral Prostheses: An Intraoperative Validation

We have previously shown in vitro that the proximal flow convergence method (FC) can be used to calculate flow through larger orifices such as normal prosthetic heart valves. To validate FC clinically, we performed intraoperative transesophageal echocardiography on 22 patients (mean age 63 ± 8 yrs, 64% female) undergoing mitral valve replacement with St Jude valve (n = 17) or Carpentier-Edwards valve (n = 5). For St Jude prostheses, peak velocities and velocity integrals through the center (V c and TVI c , respectively) and side (V s and TVI s ) orifices were interrogated separately with CW Doppler. As our in vitro model suggested about 80% of flow occurred through the side orifices, the corrected peak Velocity (V o ) is given by V o = 0.8V s + 0.2V c and the corrected velocity integral (TVI o ) by TVI o = 0.8TVI s + 0.2 TVI c . The flow rate (Q) was calculated by Q = 2 π r 2 V a where Va is the aliasing velocity. Q was multiplied by V o /(V o -V a ), a previously validated factor, to account for flattening of isotachs near the prosthetic orifice. Cardiac output (CO) calculated by (Q c * TVIo/V o ) * HR showed good correlation with thermodilution CO (Range 3.3–8.1 I/min, y = 0.87x + 0.67, r = 0.9, p < 0.001, ΔCO = -0.02 ± 0.5 I/min). Effective prosthetic orifice area (EOA) of St Jude valves, given by Q c /V o , correlated well with geometric orifice area (GOA) from the manufacturers (r = 0.7, p = 0.002, y = 1.42x + 1.47). However, calculated EOA is significantly smaller than the GOA (ΔMVA = -2.23 ± 0.49 cm 2 , p < 0.01) The proximal flow convergence method can give reliable in vivo estimates of 1) forward flow through normal mitral prostheses and 2) EOA of St Jude valves. The EOA of St Jude valve in vivo is significantly smaller than its GOA.

Evaluation of functional regurgitation flow in patients with clinically normal mitral prosthesis by transesophageal echocardiography

Evaluation of functional regurgitation flow in patients with clinically normal mitral prosthesis by transesophageal echocardiography

Assessment of normal and abnormal prosthetic mitral valves by Doppler echocardiography

Pulsed, continuous-wave, and color Doppler were performed in 165 normal mitral prostheses and 58 patients with prosthetic dysfunction (46 regurgitant and 12 obstructive valves) proved by catheterization and/or surgery. Mean mitral gradient (MG) and pressure half-time (PHT) were determined in all cases. Among normal prostheses, a wide range of both MG and PHT was observed in each type of valve and a considerable overlap between valves of different size. St-Jude's valve had the most optimal hemodynamics. Mild mitral insufficiency was detected in 14% of tissue and 24% of mechanical mitral valves. Repeat studies were performed in 30 patients over a 2.4 years period. Nine patients developed Doppler evidence of new prosthetic dysfunction, while Doppler parameters remained unchanged in 21 patients during the follow-up period. Among malfunctioning valves, Doppler correctly identified all cases of prosthetic obstruction (n = 12), and 42 of 46 regurgitant valves. We conclude that Doppler echocardiography is a very useful technique in both non-invasive assessment and follow-up of normal prosthetic valves in the mitral position and in detecting prosthetic dysfunction, especially when prosthetic obstruction is present.

Red Cell Survival in Patients with Mitral Valvular Disease and Mitral Valve Prostheses

Red cell survival times were measured in patients with mitral valvular disease, mitral ball-valve prostheses, and multiple valve prostheses. Red cell survival was shortened in patients with mitral valvular disease but not in patients who had insertion of a normally functioning mitral prosthesis or after mitral commissurotomy. Mean red cell survival was also reduced in patients who had normal mitral prostheses associated with aortic valvular disease and in patients with a leak around the mitral prosthesis. Mean red cell survival was the same in patients with multiple prostheses and in patients with a single aortic prosthesis. If a leak developed around the mitral prosthesis in patients with multiple prostheses, hemolytic anemia could develop. Renal excretion of iron and iron deficiency were demonstrated in two patients with traumatic hemolytic anemia. The urinary iron loss apparently exceeds the capacity for intestinal absorption, and parenteral iron would seem to be indicated for replacement.