New insights into the hemodynamics of pulmonary homograft patients under stress echocardiography: The contribution of pressure recovery.

BACKGROUND: The importance of pulmonary artery pressure recovery (PR) in patients with Ross procedures in whom a homograft substitutes the resected pulmonary valve, is unknown. The aim of the study was to evaluate the occurrence and extent of PR in the pulmonary artery in 65 asymptomatic patients with pulmonary homograft after Ross surgery during rest and exercise. METHODS: Stress echocardiography was performed in 65 pulmonary homograft patients and 31 controls with native pulmonary valves up to 75 W. Right ventricular systolic pressure (RVSP), transvalvular flow, mean pressure gradient (Pmean ), valve resistance, and RV stroke work were determined in the exercise (max. 75 W) and recovery phases in increments of 25 W each. RESULTS: Pulmonary homografts demonstrated significantly elevated Pmean compared to controls at all stages. When considering pressure recovery (absolute and relative PR at rest 3.8 ± 1.8 mm Hg, 42.6 ± 7.2%, respectively) and transvalvular energy loss (EL; at rest 4.5 ± 4.3 mm Hg) the homograft hemodynamics reached the level of controls. In a subgroup of patients with tricuspid regurgitation, resting RVSP was the same in homograft patients and controls (21.3 ± 6.1 vs. 20.4 ± 6.3, p = .62), despite significant different Pmax values. CONCLUSIONS: Ross patients with pulmonary homograft showed systematically increased hemodynamic parameters compared to normal pulmonary valves. These differences were abolished when PR was considered for homograft patients. The equality of RVSP values at rest in both groups shows non-invasive evidence for PR in the pulmonary system after homograft implantation. Therefore, PR appears to be an important measure in calculating the actual hemodynamics in pulmonary homografts.

Functional interaction of aortic valve and ascending aorta in patients after valve-sparing procedures.

Pressure recovery (PR) is essential part of the post stenotic fluid mechanics and depends on the ratio of EOA/AA, the effective aortic valve orifice area (EOA) and aortic cross-sectional area (AA). In patients with advanced ascending aortic aneurysm and mildly diseased aortic valves, the effect of AA on pressure recovery and corresponding functional aortic valve opening area (ELCO) was evaluated before and after valve-sparing surgery (Dacron graft implantation). 66 Patients with ascending aortic aneurysm (mean aortic diameter 57 +/- 10 mm) and aortic valve-sparing surgery (32 reimplantation technique (David), 34 remodeling technique (Yacoub)) were routinely investigated by Doppler echocardiography. Dacron graft with a diameter between 26 and 34 mm were implanted. EOA was significantly declined after surgery (3.4 +/- 0.8 vs. 2.6 +/- 0.9cm2; p < 0.001). Insertion of Dacron prosthesis resulted in a significant reduction of AA (26.7 +/- 10.2 vs. 6.8 +/- 1.1cm2; p < 0.001) with increased ratio of EOA/AA (0.14 +/- 0.05 vs. 0.40 +/- 0.1; p < 0.001) and pressure recovery index (PRI; 0.24 +/- 0.08 vs. 0.44 +/- 0.06; p < 0.0001). Despite reduction of EOA, ELCO (= EOA corrected for PR) increased from 4.0 +/- 1.1 to 5.0 +/- 3.1cm2 (p < 0.01) with reduction in transvalvular LV stroke work (1005 +/- 814 to 351 +/- 407 mmHg × ml, p < 0.001) after surgery. These effects were significantly better in patients with Yacoub technique than with the David operation. The hemodynamic findings demonstrate a valve-vessel interaction almost entirely caused by a marked reduction in the ascending AA with significant PR gain. The greater hemodynamic benefit of the Yacoub technique due to higher EOA values compared to the David technique was evident and may be of clinical relevance.

Impact of pressure recovery on the assessment of pulmonary homograft function using Doppler ultrasound.

Relevant pressure recovery (PR) has been shown to increase functional stenotic aortic valve orifice area and reduce left ventricular load. However, little is known about the relevance of PR in the pulmonary artery. The study examined the impact of PR using 2D-echocardiography in the pulmonary artery distal to the degenerated homograft in patients after Ross surgery. Ninety-two patients with pulmonary homograft were investigated by Doppler echocardiography (mean time interval after surgery 31 ± 26 months). PR was measured as a function of pulmonary artery diameter determined by computed tomography angiography. Homograft orifice area, valve resistance, and transvalvular stroke work were calculated with and without considering PR. PR decreased as the pulmonary artery diameter increased (r = -0.69, p < 0.001). Mean PR was 41.5 ± 7.1% of the Doppler-derived pressure gradient (Pmax ), which resulted in a markedly increased homograft orifice area (energy loss coefficient index [ELCOI] vs. effective orifice area index [EOAI], 1.3 ± 0.4 cm2 /m2 vs. 0.9 ± 0.4 cm2 /m2 , p < 0.001). PR significantly reduced homograft resistance and transvalvular stroke work (822 ± 433 vs. 349 ± 220 mmHg × ml, p < 0.0001). When PR was considered, the correlations of the parameters used were significantly better, and 11 of 18 patients (61%) in the group with severe homograft stenosis (EOAI <0.6 cm2 /m2 ) could be reclassified as moderate stenosis. Our results showed that the Doppler measurements overestimated the degree of homograft stenosis and thus the right ventricular load, when PR was neglected in the pulmonary artery. Therefore, Doppler measurements that ignore PR can misclassify homograft stenosis and may lead to premature surgery.