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

Alessandro.giardini@gosh.nhs.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