Division of Cardiology, Heart Institute, Children's Hospital Colorado, University of Colorado Denver, Anschutz Medical Campus, Denver, Colorado.
Department of Radiology, National Jewish Health, Denver, Colorado.
Am J Physiol Heart Circ Physiol. 2020 May 1;318(5):H1032-H1040. doi: 10.1152/ajpheart.00686.2019. Epub 2020 Mar 13.
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 ( = 0.34, = 0.001), and end-systolic volume ( = 0.30, = 0.003), cardiac index ( = 0.51, < 0.001), and the amount of aortopulmonary collateral flow ( = 0.25, = 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. 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.
腔静脉循环的特点是没有产生压力的心室的非脉动血流传播。然而，由于系统性单心室产生的压力变化，腔静脉循环中的血流仍表现出振荡波。通过腔静脉循环识别离散的血流模式对于理解单心室功能可能很重要。97 例腔静脉循环患者接受了右肺动脉相位对比 MRI，产生了特定于个体的血流波形。对预处理后的血流波形进行主成分（PC）分析。然后将主成分与功能、容量和体肺侧支循环流量的标准 MRI 指数相关联。第一主成分（PC）描述了腔静脉循环中的收缩期与舒张期主导的血流，占所有波形方差的 31.3%。第一主成分与舒张末期容积（r=0.34，P=0.001）和收缩末期容积（r=0.30，P=0.003）、心指数（r=0.51，P<0.001）和体肺侧支循环流量（r=0.25，P=0.027）相关——心室容积较小且侧支循环流量较小——与舒张期主导的腔肺血流相关。第二主成分占方差的 19.5%，描述了舒张晚期的加速与减速，与射血分数相关——舒张减速与较高的射血分数相关。描述肺动脉舒张期血流变化的主成分与单心室功能和容量有关。特别是，没有晚期加速的舒张期主导血流似乎分别与心室容积和功能的保留有关。腔静脉循环中相位和时间血流变化的血流振荡的确切生理意义尚不清楚。使用主成分分析，我们发现腔静脉循环患者的右肺动脉血流变化与单心室功能和容量有关。特别是，没有晚期加速的舒张期主导血流似乎分别与更理想的心室容积和收缩功能有关。
