Abstract 1932: The Effects of Respiration and Ventricular Diastolic Function on the Fontan Circulation: An Analysis of Pulmonary Artery Pressure Waves
Background: In Fontan circulation, pulmonary blood flow is thought to be continuous and be “sucked” into a single ventricle. However, pulmonary arterial pressure waves demonstrate complex fluctuations with respiration and heart beat. (Fig A⇓) We inspected the effects of respiration and ventricular diastolic function for Fontan circulation.
Methods: Pulmonary artery pressure waves of 9 patients for 10 cardiac cycle lengths were analyzed by discrete Fourier transform. Frequency peaks at respiratory rate and at integral multiples of pulse rate (Fig B⇓). These peaks were filtered through low- and high-pass filter, and divided into respiratory and pulsatile wave components by inverse Fourier transform (Fig C, D⇓). Diastolic function of the single ventricle was estimated by max -dp/dt, time constant tau of ventricular pressure in diastolic phase, and ventricular end-diastolic pressure (EDP) from cardiac cathter data.
Results: Respiratory fluctuation decreased in 2 patients with phrenic nerve paralysis. (2.1 and 3.5 mmHg compared with non-paralysis, 4.1±1.0 mmHg). Pulsatile waves of 6 patients without atrioventricular valve regurgitation had 2 peaks in each cardiac cycle, corresponding to atrium and ventricle contractions (Fig D⇓). The amplitude of palsatile waves had strong inverse correlation with the ventricular diastolic functions (correlation coefficient with max -dp/dt, tau, and EDP were −0.63, 0.72, and 0.85, respectively).
Conclusions: Analyses of pulmonary arterial pressure waves of Fontan patients revealed that respiration was the main driving force and that the increased pulsatile fluctuation refected decreased compliance of the single ventricle.