Clement-Guinaudeau, Stephanie

Lam, Adrian

Oshinski, John N

Padala, Muralidhar

Thourani, Vinod

English

PubMed

Adrian Lam

Stephanie Clement-Guinaudeau

Muralidhar Padala

Vinod Thourani

John N Oshinski

Springer - Publisher Connector

Post-surgical hemodynamics in aortic valve bypass (AVB) patients evaluated with phase contrast magnetic resonance (PCMR)

POSTER PRESENTATION Open Access
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 can-
not undergo valve replacement surgery due to calcifica-
tion of the ascending aorta. Aortic valve bypass (AVB)
surgery uses a conduit and prosthetic valve placed trans-
apically 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 car-
diac 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 thor-
acic aorta (location 3, flow from conduit to arch vessels).
The objective of this study is to use phase contrast mag-
netic 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.
Methods
20 patients were included in this study. Mean pressure
gradient across the aortic valve pre-surgery (ΔP) was
determined with Doppler ultrasound using the modified
Bernoulli equation. Patients underwent an MRI post-
surgery, and PCMR images were acquired along the
aorta and in the graft conduit at 5 locations, Fig 1.
Results
Flow curves generated from PCMR showed large
patient-to-patient variations in the flow patterns at the
descending thoracic aorta (location 3). Patients were
categorized into three groups: 1) patients with mono-
phasic retrograde flow over the cardiac cycle in the des-
cending thoracic aorta (10/20), 2) patients with mono-
phasic antegrade flow over the cardiac cycle in the des-
cending 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 ΔP<40 mmHg or those with
ΔP>40mmHg, Fig 2b. Patients with ΔP<40 had signifi-
cantly less retrograde flow than those with ΔP>40
mmHg (p<0.05) and flow in those patients was not sig-
nificantly different from zero (p<0.05).
Conclusions
While much patient-to-patient variability exists in the
flow patterns post AVB surgery, retrograde blood flow
in the descending thoracic aorta is related to pre-surgery
aortic valve gradient. This relationship may help with
future patient selection, as patients with pre-surgery
native aortic valve pressure gradient >40 mmHg will
most likely have retrograde flow supplying the arch
vessels.
Funding
This project was funded by the NIH T32 Training
Grant.
Author details
1Georgia Institute of Technology, Atlanta, GA, USA. 2Emory University,
Atlanta, GA, USA.
1Georgia Institute of Technology, Atlanta, GA, USA
Full list of author information is available at the end of the article
Lam et al. Journal of Cardiovascular Magnetic Resonance 2012, 14(Suppl 1):P95
http://www.jcmr-online.com/content/14/S1/P95
© 2012 Lam et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
Published: 1 February 2012
doi:10.1186/1532-429X-14-S1-P95
Cite this article as: Lam et al.: Post-surgical hemodynamics in aortic
valve bypass (AVB) patients evaluated with phase contrast magnetic
resonance (PCMR). Journal of Cardiovascular Magnetic Resonance 2012 14
(Suppl 1):P95.
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Figure 1 Aortic valve bypass surgery. Lines indicate PCMR image
acquisition locations.
Figure 2 A) Retrograde systolic aortic blood flow in the descending aorta is inversely correlated to systolic native aortic flow. B) Patients with
pre-surgery aortic valve pressure gradients greater than 40 mmHg will likely have retrograde aortic blood flow.
Lam et al. Journal of Cardiovascular Magnetic Resonance 2012, 14(Suppl 1):P95
http://www.jcmr-online.com/content/14/S1/P95
Page 2 of 2


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Journal of Cardiovascular Magnetic Resonance

Lam Adrian

Clement-Guinaudeau Stephanie

Padala Muralidhar

Thourani Vinod

Oshinski John N

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Post-surgical hemodynamics in aortic valve bypass (AVB) patients evaluated with phase contrast magnetic resonance (PCMR)

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