Circulatory Response to Rapid Volume Expansion and Cardiorespiratory Fitness in Fontan Circulation

Thomas Möller,Elisabeth Edvardsen,Guro Grindheim,Simone Diab,Assami Rösner,Erik Thaulow,Vibeke Klungerbo,Alvaro Köhn-Luque,Henrik Holmstrøm,Gaute Døhlen,Henrik Brun

doi:10.1007/s00246-021-02802-y

Abstract

The role of dysfunction of the single ventricle in Fontan failure is incompletely understood. We aimed to evaluate hemodynamic responses to preload increase in Fontan circulation, to determine whether circulatory limitations in different locations identified by experimental preload increase are associated with cardiorespiratory fitness (CRF), and to assess the impact of left versus right ventricular morphology. In 38 consecutive patients (median age = 16.6 years, 16 females), heart catheterization was supplemented with a rapid 5-mL/kg body weight volume expansion. Central venous pressure (CVP), ventricular end-diastolic pressure (VEDP), and peak systolic pressure were averaged for 15‒30 s, 45‒120 s, and 4‒6 min (steady state), respectively. CRF was assessed by peak oxygen consumption (VO2peak) and ventilatory threshold (VT). Median CVP increased from 13 mmHg at baseline to 14.5 mmHg (p < 0.001) at steady state. CVP increased by more than 20% in eight patients. Median VEDP increased from 10 mmHg at baseline to 11.5 mmHg (p < 0.001). Ten patients had elevated VEDP at steady state, and in 21, VEDP increased more than 20%. The transpulmonary pressure difference (CVP‒VEDP) and CVP were consistently higher in patients with right ventricular morphology across repeated measurements. CVP at any stage was associated with VO2peak and VT. VEDP after volume expansion was associated with VT. Preload challenge demonstrates the limitations beyond baseline measurements. Elevation of both CVP and VEDP are associated with impaired CRF. Transpulmonary flow limitation was more pronounced in right ventricular morphology. Ventricular dysfunction may contribute to functional impairment after Fontan operation in young adulthood.ClinicalTrials.govidentifier NCT02378857

Highlights

Palliative operations for univentricular congenital heart defects are among the most frequently performed procedures in pediatric open-heart surgery
While pulmonary vascular resistance has been the focus of non-invasive interventions, our data suggest the equal importance of impaired ventricular function for long-term function of Fontan circulation
It will be of interest if the pressure rise in the preload-stressed Fontan circulation corresponds with the directly measurable limitations of myocardial contractile reserve

Summary

Introduction

Palliative operations for univentricular congenital heart defects are among the most frequently performed procedures in pediatric open-heart surgery. Fontan-type palliation has saved many lives during the last four to five decades [1]. With few exceptions, patients live with major limitations in cardiorespiratory fitness (CRF) [2], and the ability to improve performance and predict the post-Fontan clinical course is disappointingly poor. Long-term failure of the low-energy/low-flow Fontan circulation is inevitable [3]. During diagnostic right heart catheterization, elevation of the central venous pressure (CVP), often called Fontan pressure, is the most informative functional variable. Chronically elevated pulmonary vascular resistance has been considered the key to

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