Abstract Body (Do not enter title and authors here): Introductions: Pulmonary regurgitation is a diastolic phenomenon but little is known of the impact of RV-PA conduit interventions on RV diastolic function. We measured the acute effects of PPVI or stent implantation on RV diastolic relaxation with high-fidelity pressure catheters.
Methods: Right and left heart pressure measurements with Millar Mikro-Cath pressure catheters in children undergoing RV-PA conduit intervention, who had also had an MRI. The relaxation time constant (RV-tau) was calculated as the time constant of the monoexponential pressure decay in the interval between the pressure at dP/dt_min (P₀) to when the pressure fell to 10% of P₀.
Result: The age for PPVI (n=29) or stent (n=21) implantations were (mean ± sd): 14 ± 2.8 and 11.8 ± 4.2 years, respectively. RV-tau decreased 33% in the PPVI group and increased 11% in the Stent group (Table 1). The absolute value of RV dP/dt_min decreased 9% in the Stent but not the PPVI group. The absolute value of LV dP/dt_min increased 12% in the PPVI but not the Stent group. There was a small increase in peak VO₂ at the last follow-up (median 1.04 years, range 0.15-4.69 years) in the PPVI but not the Stent group compared to baseline (from 27.1 to 31.6 ml/kg/min, p = 0.01). The Δpeak VO₂ correlated with ΔRV-tau (r = 0.75, p = 0.01, n = 10) but not with ΔRV-PA gradient or pre pulmonary regurgitation fraction.
Conclusions: PPVI results in faster RV diastolic relaxation. This may contribute to post-procedure enhanced exercise capacity more than either RV pressure and volume unloading alone.