Upload
others
View
6
Download
0
Embed Size (px)
Citation preview
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