Progressive ventricular remodelling in children with repaired tetralogy of Fallot may or may not result in the need for pulmonary valve replacement. We aimed to model and compare the rates of right and left ventricular adaptation over time, as assessed by cardiac MRI after surgical repair of tetralogy of Fallot, in children who did or did not require pulmonary valve replacement later in adolescence.

Single-centre, retrospective cohort study from 2000 to 2020 including patients with tetralogy of Fallot who had complete surgical repair before 24 months.

From 214 patients included in this analysis, 142 (66.3%) had pulmonary valve replacement at a median age of 12 years (interquartile range 9–15.5) during follow-up. Assessing 323 cardiac MRI studies from 201 patients commencing from a median age of 9.4 years (interquartile range 5.9–12.3), the group that required pulmonary valve replacement later during the follow-up had a steeper time-related right ventricular dilation trajectory than non-pulmonary valve replacement patients: the increment in right ventricular end-diastolic volume index was 19.4 versus 2.8 ml/m2/log2year, P < 0.001; also, right ventricular end-systolic volume index incremented more quickly, at 11.9 versus 0.8 ml/m2/log2year, P < 0.001. Left ventricular end-diastolic volume index increased more quickly in patients who eventually had pulmonary valve replacement, at 7.2 versus 1.5 ml/m2/log2year, P = 0.005; the same occurred for indexed left ventricular end-systolic volume at 3.2 versus –0.4 ml/m2/log2year, P = 0.001.

Early right and left ventricular dilation over time are identifiable by cardiac MRI in patients destined to require pulmonary valve replacement following tetralogy of Fallot repair.

To evaluate the effect of a continuous infusion of basic fibroblast growth factor on the adaptive potential of the right ventricular myocardium after 30 days of mechanically induced overload in rats.

We banded the pulmonary trunk, so as to increase the systolic workload of the right ventricle, in six Lewis/HanHsd rats at the age of 11 weeks, using six adult rats as controls. The six adult rats were also banded and received an additional continuous infusion of basic fibroblastic growth factor, using six rats with a continuous infusion of basic fibroblastic growth factor only as controls. We analysed the functional adaptation and structural changes of the right ventricular myocardium, blood vessels, and interstitial tissue 30 days after the increased afterload.

The pulmonary artery banding induced an increase in the right ventricular free wall thickness of banded rats when compared with controls, which was mainly justified by an increase in cardiomyocyte area and in the percentage of extracellular fibrosis. The infusion of basic fibroblastic growth factor promotes a more extensive capillary network in banded rats (p < 0.001), which modulates the compensatory response of the right ventricle, promoting the hypertrophy of contractile elements and limiting the areas in which fibrosis develops (p < 0.001).

The subcutaneous infusion with osmotic pumps was a valid and reproducible method of delivering basic fibroblast growth factor to heart tissue. This infusion contributed to better preserve the right ventricular capillary network, hampering the development of interstitial fibrosis.