[Hemodynamic difference accounted for the orientation of a Björk-Shiley mitral prosthesis: a color Doppler echocardiographic study].
To determine whether the orientation of the major orifice of a mitral tilting disc prosthesis affects hemodynamics, intracavitary blood flow patterns were studied in 45 patients with well-functioning Björk-Shiley mitral prosthesis using color Doppler flow imaging. The major orifice was oriented towards the septum in 23 patients (12 men, 11 women, age 58 +/- 11 years; group S), and towards the posterior wall in 22 patients (8 men, 14 women, age 55 +/- 9 years; group P). 1) The left ventricular end-diastolic dimensions (S: 4.8 +/- 0.9 cm, P: 5.2 +/- 1.0 cm), end-systolic dimensions (S: 3.6 +/- 0.9 cm, P: 3.8 +/- 1.2 cm), and left atrial dimensions (S: 5.0 +/- 1.0 cm, P: 4.7 +/- 0.9 cm) did not differ significantly between the 2 groups. 2) The peak mitral flow velocities (S: 1.43 +/- 0.38 m/sec, P: 1.43 +/- 0.27 m/sec), pressure gradients (S: 8.5 +/- 4.0 mmHg, P: 8.4 +/- 3.1 mmHg), and pressure half-times (S: 94.0 +/- 19.0 msec, P: 86.5 +/- 21.7 msec) did not differ significantly between the 2 groups. 3) Although mitral regurgitation was detected in 8 patients (35%) in the S group and in 2 patients (9%) in the P group, hemodynamically significant regurgitation was detected in only 4 patients in the S group (3 mild, one moderate). 4) The patients in the S group had reversed intracavitary blood flow; mitral flow was first directed towards the left ventricular outflow tract during diastole, while the outflow pattern was displaced into the left ventricular inflow tract.(ABSTRACT TRUNCATED AT 250 WORDS)