poor aortic distensibility following norwoodaz9194.vo.msecnd.net/pdfs/120401/27.01.pdf · 2012. 5....
TRANSCRIPT
Poor aortic distensibility following Norwood
procedure is associated with reduced
ventricular function
Alessandro Giardini, Giovanni Biglino, Silvia Schievano,
Jennifer Steeden, Catriona Baker, Martin Kostolny,
Victor Tsang, Tain-Yen Hsia, Andrew Taylor
Great Ormond Street Hospital for Children
London - UK
Background
• ? long-term function of the systemic right ventricle in
Fontan circulation
• ⬆ afterload � premature ventricular dysfunction
• Aortic coarctation
⬆ ⬆⬆
⬆
⬆
•
• Norwood procedure:
•⬇ distensibility of the reconstructed aorta
•⬆ afterload ?
Aortic coarctation
⬆ aortic impedance ⬆⬆Afterload
⬆ wave reflection
Study aims
• Assess mechanical properties of the ascending
aorta in single ventricle patients
• Study effect on ventricular function and
vascular-arterial coupling
Methods
• 21 children (age 4.0±1.4 y) with MRI before Fontan
completion
10 HLHS (aortic arch reconstruction with
homograft)
• Standard MRI sequences
• Blood pressure measured non-invasively
11 controls (other forms of single ventricle
with no aortic reconstruction)
Methods - Aortic wave speed and distensibility
• Wave speed (c) from
ascending aortic MR flow
data
Mean flow velocity (m/sec)
Ln area
• Aortic distensibility (D)
• Circumferential stress (σ) and strain (ε)
ε = ∆d/ddiastσ =Pd
2h
Mean flow velocity (m/sec)
Methods - Wave intensity analysis
FCW = forward compression
wave (ventricular contraction)
FEW = forward expansion
wave (ventricular
relaxation)relaxation)
Normal subjects:⇨⇨⇨⇨ FCW peak ~ invasive dP/dt
⇨⇨⇨⇨ FEW peak ~ ventricular relaxation time constant (ττττ)
Var iable HLHS Control p va lue
Age (years) 3.4 ± 1.0 4.6 ± 1.5 0.02
Weight (Kg) 14.5 ± 2.5 15.9 ± 4.2 0.19
Body s urface area (m2) 0.61 ± 0.06 0.65 ± 0.11 0.15
Heart rate (bpm) 107 ± 17 102 ± 12 0.21
Ventricular EF (%) 52 ± 6 61 ± 6 0.003
Results - Baseline characteristics
Ventricular EF (%) 52 ± 6 61 ± 6 0.003
Stroke volume (mL) 29.9 ± 5.0 40.9 ± 18.1 0.04
Ventricle type (n)
R ight
Left
10
0
2
9
0.0002
Aort ic press ure pulse (mmHg) 39 50 0.12
Re-coarctat ion 0 - -
Results – Aortic distensibilityp=0.004
HLHS Control
Results - Ascending aorta diameterp<0.0001
HLHS Control
Results - Distensibility and diameter
Results – Aortic wall strain
p=0.0001
HLHS Control
Results – Effect of the patch
σσσσ
εεεε
ControlHLHS
Results – Effect of the patch
σσσσσ =
Pd
2h
εεεε
Control
HLHS
Results - Forward compression wave (FCW)p=0.0002
HLHS Control
Results - Forward expansion wave (FEW)
p=0.001
HLHS Control
Conclusions
Arch Reconstruction
⬇ ascending aorta distensibility
⬇ systolic (FCW) and diastolic (FEW) function⬇
Ventricular-arterial coupling highly unfavorable
? aging and hypertension
? smaller patches or different materials