Rest and exercise hemodynamics before and after valve replacement - A combined Doppler/catheter study

Background: Hemodynamic improvement is a common finding following valve rep lacement. However, despite a normally functioning prosthesis and normal lef t ventricular ejection fraction, some patients may show an abnormal hemodyn amic response to exercise. Methods: In a combined catheter/Doppler study, rest and exercise hemodynami cs were evaluated in 23 patients following aortic (n = 12) (Group 1) or mit ral valve (n = 11) (Group 2) replacement and compared with preoperative fin dings. Patient selection was based on absence of coronary artery disease an d left ventricular failure as shown by preoperative angiography. Cardiac ou tput, pulmonary artery pressure, pulmonary capillary pressure, and pulmonar y resistance were measured by right heart catheterization, whereas the grad ient across the valve prosthesis was determined by Doppler echocardiography . Postoperative evaluation was done at rest and during exercise. The mean f ollow-up was 8.2+/-2.2 years in Group 1 and 4.2+/-1 years in Group 2. Results: With exercise, there was a significant rise in cardiac output in b oth groups. In Group 1, mean pulmonary pressure/capillary pressure decrease d from 24 +/- 9 / 18 +/- 9 mmHg preoperatively to 18 +/- 2 / 12 +/- 4 mmHg postoperatively (p < 0.05), and increased to 43 +/- 12 / 30 +/- 8 mmHg with exercise (p < 0.05). The corresponding values for Group 2 were 36 +/- 12 / 24 +/- 6 mmHg preoperatively, 24 +/- 7 /17 +/- 6 mmHg postoperatively (p < 0.05), and 51 +/- 2 / 38 +/- 4 mmHg with exercise (p < 0.05). Pulmonary va scular resistance was 109 +/- 56 dyne.s.cm(-5) preoperatively, 70 +/- 39 dy ne.s.cm(-5) postoperatively (p < 0.05), and 70 +/- 36 dyne.s.cm(-5) with ex ercise in Group 1. The corresponding values for Group 2 were 241 +/- 155 dy ne.s.cm(-5), 116 +/- 39 dyne.s.cm(-5) (p < 0.05), and 104 +/- 47 dyne.s.cm( -5). There was a significant increase in the gradients across the valve pro sthesis in both groups, showing a significant correlation between the gradi ent at rest and exercise. No correlation was found between valve prosthesis gradient and pulmonary pressures. Conclusion: Exercise-induced pulmonary hypertension and abnormal left ventr icular filling pressures seem to be a frequent finding following aortic or mitral valve replacement. Both hemodynamic abnormalities seem not to be det ermined by obstruction to flow across the valve prosthesis and may be conce aled, showing nearly normal values at rest but a pathologic response to phy sical stress.