Abstract
BackgroundBranch pulmonary artery (PA) stenosis (PAS) commonly occurs in patients with congenital heart disease (CHD). Prior studies have documented technical success and clinical outcomes of PA stent interventions for PAS but the impact of PA stent interventions on ventricular function is unknown. The objective of this study was to utilize 4D flow cardiovascular magnetic resonance (CMR) to better understand the impact of PAS and PA stenting on ventricular contraction and ventricular flow in a swine model of unilateral branch PA stenosis.Methods18 swine (4 sham, 4 untreated left PAS, 10 PAS stent intervention) underwent right heart catheterization and CMR at 20 weeks age (55 kg). CMR included ventricular strain analysis and 4D flow CMR.Results4D flow CMR measured inefficient right ventricular (RV) and left ventricular (LV) flow patterns in the PAS group (RV non-dimensional (n.d.) vorticity: sham 82 ± 47, PAS 120 ± 47; LV n.d. vorticity: sham 57 ± 5, PAS 78 ± 15 p < 0.01) despite the PAS group having normal heart rate, ejection fraction and end-diastolic volume. The intervention group demonstrated increased ejection fraction that resulted in more efficient ventricular flow compared to untreated PAS (RV n.d. vorticity: 59 ± 12 p < 0.01; LV n.d. vorticity: 41 ± 7 p < 0.001).ConclusionThese results describe previously unknown consequences of PAS on ventricular function in an animal model of unilateral PA stenosis and show that PA stent interventions improve ventricular flow efficiency. This study also highlights the sensitivity of 4D flow CMR biomarkers to detect earlier ventricular dysfunction assisting in identification of patients who may benefit from PAS interventions.
Highlights
Branch pulmonary artery (PA) stenosis (PAS) commonly occurs in patients with complex congenital heart disease (CHD)
left PA (LPA) diameters at the second, more distal, measurement location were similar between sham and stent interventions
We identified significantly inefficient right ventricular (RV) and left ventricle (LV) flow associated with unilateral branch pulmonary artery stenosis (PAS), even in the setting of normal heart rate, ejection fraction (EF) and End-diastolic volume (EDV) index
Summary
Branch pulmonary artery (PA) stenosis (PAS) commonly occurs in patients with complex congenital heart disease (CHD). Measurement of time-varying velocity of blood flow with 4D flow CMR can precisely define ventricular flow patterns and permit calculation of biomarkers of mechanical efficiency including kinetic energy and vorticity [15, 16]. Changes in these ventricular flow biomarkers are believed to represent early signs of cardiac dysfunction [17] as momentum lost through inefficient ventricular flow increases ventricular energy demand and contributes to adverse ventricular remodeling [18, 19]. The objective of this study was to utilize 4D flow cardiovascular magnetic resonance (CMR) to better understand the impact of PAS and PA stenting on ventricular contraction and ventricular flow in a swine model of unilateral branch PA stenosis
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