OBJECTIVES Previous work suggests that aortic root and valve prostheses alter blood flow patterns in the ascending aorta, creating aberrant haemodynamics compared with those of healthy volunteers. Various valve designs have been proposed to better restore physiological haemodynamics. In this study, magnetic resonance imaging (MRI) was used to non-invasively assess three-dimensional (3D) ascending aortic haemodynamics after aortic root replacement (ARR) with a mechanical valved conduit postulated to create less turbulent blood flow. METHODS Ten patients (40 ± 9 years) underwent transthoracic echocardiography and contrast-enhanced multidimensional four-dimensional (4D) flow MRI at 1.5 T after ARR with an On-X mechanical valved conduit. Preoperative 4D flow MRI was available in 7 patients. Ten age- and gender-matched healthy volunteers (42 ± 13 years) were also analysed to characterize physiological flow. The presence of vortex/helix formation was graded by two blinded observers. Peak transvalvular pressure gradients were computed using the simplified Bernoulli equation. Patients' postoperative pressure gradients and helicity/vorticity grades were compared with preoperative gradients and those from healthy volunteers. RESULTS Intra- and interobserver ratings showed good agreement (κ = 0.93, P < 0.01 and κ = 0.84, P < 0.01, respectively). Highly helical and/or vortical flow was observed in all patients preoperatively, which was significantly reduced postoperatively (P < 0.01 and <0.01, respectively), restoring similar flow patterns similar to those seen in volunteers (P = 0.56 and 0.56). Peak transvalvular pressure gradients (ΔP) were also significantly reduced [43 ± 21 vs 12 ± 7 mmHg, P < 0.05 (Echo); 48 ± 22 vs 16 ± 9 mmHg, P < 0.05 (MRI)], but remained significantly higher than those of volunteers (6 ± 1 mmHg, P < 0.01). CONCLUSIONS Preliminary evidence suggests that ARR with an On-X mechanical valve significantly reduces aberrant aortic haemodynamics, producing flow patterns that resemble those in healthy volunteers.
- Aortic valve replacement
- Magnetic resonance imaging
- Mechanical heart valve prosthesis
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Cardiology and Cardiovascular Medicine