Post-surgical hemodynamics in aortic valve bypass (AVB) patients evaluated with phase contrast magnetic resonance (PCMR)
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Post-surgical hemodynamics in aortic valve bypass (AVB) patients evaluated with phase contrast magnetic resonance (PCMR) Adrian Lam1*, Stephanie Clement-Guinaudeau2, Muralidhar Padala2, Vinod Thourani2, John N Oshinski1,2 From 15th Annual SCMR Scientific Sessions Orlando, FL, USA. 2-5 February 2012 Background Many high-risk patients with severe aortic stenosis cannot undergo valve replacement surgery due to calcification of the ascending aorta. Aortic valve bypass (AVB) surgery uses a conduit and prosthetic valve placed transapically into the left ventricle to divert flow from the apex of the heart through the conduit and prosthetic valve to the descending thoracic aorta to improve cardiac output, Fig 1. The hemodynamics resulting from AVB are not well understood. Specifically, there appears to be significant patient-to-patient variability in the amount of retrograde blood flow in the descending thoracic aorta (location 3, flow from conduit to arch vessels). The objective of this study is to use phase contrast magnetic resonance (PCMR) to examine the hemodynamics in AVB patients and determine the relationship between pre-surgery native aortic valve pressure gradient and post-surgery retrograde blood flow in the thoracic aorta.
phasic retrograde flow over the cardiac cycle in the descending thoracic aorta (10/20), 2) patients with monophasic antegrade flow over the cardiac cycle in the descending thoracic aorta (5/20) and 3) patients with multi-phasic (mixed antegrade and retrograde) flow (5/ 20). The amount of retrograde flow in the descending thoracic aorta (location 3) was inversely correlated to blood flow from the native aorta (location 1), Fig 2a. This indicates that despite variations in the direction or source of the flow, the volume of blood flow to the arch vessels remains relatively constant among patients. Additionally, patients were divided into two groups: those with pre-surgery ΔP40mmHg, Fig 2b. Patients with ΔP40 mmHg (p
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