Abstract Background/Introduction In pulmonary vein stenosis (PVS), serial echocardiograms are the mainstay in assessment of pulmonary vein disease. Development of gradients in stenotic pulmonary veins indicate progression of disease and influences timing of intervention. However, pulmonary vein gradients should be interpreted in the context of relative branch pulmonary artery (PA) flows to avoid misinterpretation of worsening PVS. To date, the comparison of branch PA flows derived from echocardiography compared to gold-standard from MRI has not been described. Purpose To determine if branch PA flows calculated using velocity time integral (VTI) correlate with MRI. Methods Single-center retrospective assessment of cardiac MRIs and echocardiograms in pediatric patients with pulmonary vein stenosis between February 2019 to May 2022. Cardiac MRIs and echocardiograms obtained within a 6-month period were compared. All causes and severity of PVS were included. Patients were excluded if echocardiographic assessment did not adequately visualize either branch PA or pulse wave Dopplers in the PAs were not performed. 20 patients with a mean age of 7.72 ± 5.93 years were included. Branch PA flows were derived using PA diameter in systole from the high parasternal view from which cross-sectional area (CSA) was calculated using CSA = pi(radius)^2. Using pulse wave Doppler in the branch PAs, VTI was measured as an averaged area under the curves over 3 beats. Relative branch PA flows were calculated using a product of CSA and VTI. We present branch PA flows indexed to body surface area. Results Mean RPA flows by VTI and MRI were 2.18 ± 1.36L/min/m2 and 2.34 ± 1.29L/min/m2, respectively. Mean LPA flows by VTI and MRI were 1.64±0.77L/min/m2 and 1.94±1.13L/min/m2, respectively. There were statistically significant correlations in branch PA flows comparing VTI to MRI (RPA correlation coefficient 0.549, p=0.02, LPA correlation coefficient 0.621, p=0.01). Conclusion Relative branch PA flows calculated using VTI correlate significantly with gold-standard from MRI. Lower correlation in the RPA may be due to Doppler angle. This is a feasible, complementary tool easily integrated as part of the standard echocardiographic assessment of PVS, that allows early detection of disease progression while decreasing the frequency of general anesthesia required for MRIs in young children. Expansion to a larger cohort is necessary to strengthen demonstrated correlations. Future work includes integration of branch PA flows in addition to pulmonary vein gradients to develop a PVS severity score in pediatrics to guide management.
Read full abstract