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Introduction
The palliation for single-ventricle patients generally involves three stages of surgery culminating in the total cavopulmonary connection (TCPC) with, most commonly, either an extracardiac (EC) or intra-atrial (IA) connection. While there have been advancements in clinical management, these patients may develop significant complications in the long term including decreased exercise tolerance, pulmonary arteriovenous malformations, heart failure or protein-losing enteropathy. 1-3
The complex physiology makes it difficult to predict postoperative haemodynamic performance during rest or exercise conditions. 4-6 The haemodynamics is significantly different from the biventricular circulation; the single ventricle is forced to perform the work of two ventricles. Several studies have modelled and characterised TCPC haemodynamic parameters such as energy dissipation, wall shear stress or flow resistance. 7-11 It has been suggested that patient outcome may be related to TCPC haemodynamic parameters such as power loss (PL) 8 ; however, it is unclear to what extent the haemodynamics of the surgically constructed TCPC impacts the ability of the patient to exercise. Understanding these dynamics might have critical implications for the management of these patients; it could identify specific markers that control outcomes, can potentially elucidate mechanisms of Fontan failure and may be used for the development of optimal surgical and/or clinical management strategies 12 that may allow for these children to exercise better and improve their ability to keep up with their peers, ultimately improving their quality of life.
The goal of this study was to use patient-specific data to investigate the association between haemodynamic energy dissipation within the TCPC and metabolic exercise test performance.
Methods
A total of 30 single-ventricle patients who underwent TCPC were included. Consecutive patients were taken from Georgia Tech-Children's Hospital of Philadelphia (CHOP) Fontan database that had completed standard graded metabolic exercise testing as well as resting and exercise cardiac MR (CMR) at CHOP using a 1.5 T Avanto Whole Body system (Siemens Medical Solutions, Malvern, Pennsylvania, USA). Patient data are summarised in table 1 . Informed consent was obtained from all patients and all the study protocols complied with the Institutional Review Boards of CHOP and the Georgia Institute of Technology.
Table 1
Mean±SD | |
Age | 19.4±6.2 years |
Body surface area | 1.7±0.2 m2 |
Gender (M/F) | 16/14 |
IVC connection type (intra-atrial/extra-cardiac) | 21/9 |
Systemic venous return at rest (at VAT) |