Does Maintenance of Pulmonary Blood Flow Pulsatility at the Time of the Fontan Operation Improve Hemodynamic Outcome in Functionally Univentricular Hearts?

Abstract

It is unclear whether residual anterograde pulmonary blood flow (APBF) at the time of Fontan is beneficial. Pulsatile pulmonary flow may be important in maintaining a compliant and healthy vascular circuit. We, therefore, wished to ascertain whether there was hemodynamic evidence that residual pulsatile flow at time of Fontan promotes clinical benefit. 106 consecutive children with Fontan completion (1999-2018) were included. Pulmonary artery pulsatility index (PI, (systolic pressure-diastolic pressure)/mean pressure)) was calculated from preoperative cardiac catheterization. Spectral analysis charted PI as a continuum against clinical outcome. The population was subsequently divided into three pulsatility subgroups to facilitate further comparison. Median PI prior to Fontan was 0.236 (range 0-1). 39 had APBF, in whom PI was significantly greater (median: 0.364 vs. 0.177, Mann-Whitney p < 0.0001). There were four early hospital deaths (3.77%), and PI in these patients ranged from 0.214 to 0.423. There was no correlation between PI and standard cardiac surgical outcomes or systemic oxygen saturation at discharge. Median follow-up time was 4.33 years (range 0.0273-19.6), with no late deaths. Increased pulsatility was associated with higher oxygen saturations in the long term, but there was no difference in reported exercise tolerance (Ross), ventricular function, or atrioventricular valve regurgitation at follow-up. PI in those with Fontan-associated complications or the requiring pulmonary vasodilators aligned with the overall population median. Maintenance of pulmonary flow pulsatility did not alter short-term outcomes or long-term prognosis following Fontan although it tended to increase postoperative oxygen saturations, which may be beneficial in later life.

Keywords: Congenital heart surgery; Fontan; Pulmonary vascular resistance.

Fig. 1

Analysis of standard surgical outcome measures as a function of pulsatility. Results from subgroup analysis are shown, with Kruskal–Wallis p values; a Ventilation time, b Chest drainage duration, c PICU stay, d Total hospital stay, e SaO₂ at discharge. Abbreviations—PI pulsatility index; PICU pediatric intensive care unit; SaO₂ systemic arterial oxygen saturation

Fig. 2

Long-term oxygenation status at 1-year and last follow-up. Spectral analysis is presented on the left-hand side, at a 1-year and c last follow-up, with calculation of Pearson r and associated p value. Light gray represents data points from the ‘low PI,’ medium gray from the ‘medium PI,’ and dark gray from the ‘high PI’ group. On the right, results from subgroup analysis are shown, at b 1-year and d last follow-up, with Kruskal–Wallis p values

Fig. 3

PI and adverse long-term outcomes. Distribution of Pulsatility Index (PI) in Patients with Fontan-associated complications, and those requiring pulmonary vasodilator or diuretic therapy at last follow-up. Median and interquartile range (IQR) are plotted. Abbreviations—FAD Fontan-associated disease or complications; PI pulsatility index