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Pathophysiology of the Systemic Right Ventricle in Hypoplastic Left Heart Syndrome

Student thesis: Doctoral ThesisDoctor of Medicine

Background: Hypoplastic left heart syndrome (HLHS) describes a spectrum of
underdevelopment of the left heart, rendering it incapable of supporting the
systemic circulation. Improved results from Norwood palliation mean more
children are surviving into later childhood. The assessment of right ventricular
(RV) function is an important prognostic factor, but is complicated by wide
heterogeneity and complex geometry. Novel MRI and echocardiographic
techniques are non-invasive and may offer insight into the pathophysiology of
the systemic RV.

Methods: Current methods for assessing the RV were reviewed. MRI and
echocardiography were used and compared prospectively in HLHS patients to
investigate RV performance and changes in ventricular volumetry across the
palliative stages. The novel approach of pre-Fontan assessment using MRI
and central venous pressure (CVP) measurement alone was compared to the
current literature.

Results: Echocardiographic subjective assessment of RV function in HLHS had
little concordance with MRI ejection fraction, showing the limitation of using this
method alone. MRI demonstrated significant RV volume unloading after hemi-
Fontan, with a shift of the Starling curve suggesting improved contractility. The
novel pre-Fontan assessment showed no difference in outcomes from the
published literature. Tissue Doppler time intervals were significantly different in
HLHS patients compared to normal hearts. Differences were also seen in tissue Doppler indices and speckle tracking derived strain between those with a significant residual left ventricle and those without

Conclusions: Novel MRI and echocardiographic techniques give unique and
reproducible insights into the morphologic and functional development of the
systemic RV across the stages of surgical palliation. Important differences
between the morphological subtypes were also noted. Based on this MD
thesis, reliable, easy to use, reproducible and non-invasive screening tools
have been established, validated and used for longitudinal follow-up. These
techniques may also lead to improved follow-up: predicting, or possibly
preventing systemic RV failure.
Original languageEnglish
Awarding Institution
Supervisors/Advisors
Award date2013

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