Flow profile characteristics in Fontan circulation are associated with the single ventricle dilation and function: principal component analysis study

Abstract

The Fontan circulation is characterized as a nonpulsatile flow propagation without a pressure-generating ventricle. However, flow through the Fontan circulation still exhibits oscillatory waves as a result of pressure changes generated by the systemic single ventricle. Identification of discrete flow patterns through the Fontan circuit may be important to understand single ventricle performance. Ninety-seven patients with Fontan circulation underwent phase-contrast MRI of the right pulmonary artery, yielding subject-specific flow waveforms. Principal component (PC) analysis was performed on preprocessed flow waveforms. Principal components were then correlated with standard MRI indices of function, volume, and aortopulmonary collateral flow. The first principal component (PC) described systolic versus diastolic-dominant flow through the Fontan circulation, accounting for 31.3% of the variance in all waveforms. The first PC correlated with end-diastolic volume ( R = 0.34, P = 0.001), and end-systolic volume ( R = 0.30, P = 0.003), cardiac index ( R = 0.51, P < 0.001), and the amount of aortopulmonary collateral flow ( R = 0.25, P = 0.027)—lower ventricular volumes and a smaller volume of collateral flow—were associated with diastolic-dominant cavopulmonary flow. The second PC accounted for 19.5% of variance and described late diastolic acceleration versus deceleration and correlated with ejection fraction—diastolic deceleration was associated with higher ejection fraction. Principal components describing the diastolic flow variations in pulmonary arteries are related to the single ventricle function and volumes. Particularly, diastolic-dominant flow without late acceleration appears to be related to preserved ventricular volume and function, respectively. NEW & NOTEWORTHY The exact physiological significance of flow oscillations of phasic and temporal flow variations in Fontan circulation is unknown. With the use of principal component analysis, we discovered that flow variations in the right pulmonary artery of Fontan patients are related to the single ventricle function and volumes. Particularly, diastolic-dominant flow without late acceleration appears to be related to more ideal ventricular volume and systolic function, respectively.