Pulmonary vein stenosis

There has been increasing recognition of acquired pulmonary vein stenosis (PVS) in extremely premature newborns. This entity seems to be developing at variable age, but as late as 6 months of corrected age. The entity may be related to inflammatory fibrosis and seems to be markedly affecting the osteum of the pulmonary veins. This may lead to post-capillary pulmonary hypertension, although many of these infants may also have a contribution of pulmonary arterial hypertension (pre-capillary) superimposed on the phenotype. These infants may have significant pulmonary hypertension and right ventricular failure. There has been some reports associating this entity with other inflammatory or vascular diseases of the newborn, such as necrotizing enterocolitis or retinopathy of prematurity. Pulmonary vein stenosis is often suspected by echcocardiography when there is a monophasic Doppler flow profile with a mean gradient of more than 4 mmHg. Echocardiography has many limitations. PVS may not be detected because of poor acoustic windows (often these infants have severe pulmonary phenotype rendering the scanning quite challenging). Further, some infants have also concomitant tracheostomy (or other apparatus for respiratory support), making it challenging to obtain a crab view. Infants with complete osteum atresia may be missed, since PVS is often detected when there is residual accelerated flow through the narrowed osteum. Echocardiography may not appreciate the extent of the pulmonary venous disease, since there may be long-segment involvement. The presence of pulmonary venous disease at the osteum may only be the hallmark of a more profound proximal venous disease. Acceleration of flow may also be "flow-driven", but the loss of the biphasic or triphasic venous pattern may be a clue indicating that there is a stenosis. Echocardiography is practical since it allows for concomitant evaluation of the right ventricular function and presence of shunt. Nonetheless, one should always pay attention to the pulmonary veins when evaluating extremely premature newborns, even if their normal connection has been objectified in the past. Especially when suspecting high pulmonary pressures, there should be an exhaustive evaluation of the pulmonary veins and the left sided structures (mitral valve, aortic valve, left ventricular performance and pulmonary venous drainage). Some centres advocate for computed tomography, magnetic resonance imaging and/or cardiac catheterization angiography in these infants. The management is controversial and many strategies have been described: pulmonary vasodilators to redistribute the blood flow to unaltered areas of pulmonary venous drainage, cath-based procedures (balloon, stent), surgical suture-less repair, immunomodulation, lung transplant. These cases should be managed by an experienced pulmonary hypertension team. Some interesting references are provided below. Here are clips that exemplify pulmonary venous stenosis in the context of prematurity. 

From this article: Lin Y, Amin EK, Keller RL, Teitel DF, Nawaytou HM. Doppler Echocardiographic Features of Pulmonary Vein Stenosis in Ex-Preterm Children. J Am Soc Echocardiogr. 2022 Apr;35(4):435-442. doi: 10.1016/j.echo.2021.12.015. Epub 2022 Jan 2. PMID: 34986343.

"To assess individual veins with concern for stenosis, angiograms were extracted for all catheterizations with pulmonary vein mean pressure gradients > 3 mm Hg and those from patients with PVS noted in their medical records. Veins from these latter patients were reviewed to allow consideration of veins that were completely occluded or those with low blood flow resulting in a mean pressure gradient ≤ 3 mm Hg. ... In an attempt to quantify phasic flow in the pulmonary veins, we calculated the absolute difference between the peak systolic velocity and the peak diastolic velocity as well as the pulsatility index. The pulsatility index was calculated as (peak systolic velocity − peak diastolic velocity)/mean velocity during the cardiac cycle. Return of Doppler velocity to baseline was defined as a decrease of velocity to <0.20 m/sec at any time during the cardiac cycle. The echocardiograms were also evaluated for the presence of pulmonary hypertension and right ventricular dysfunction. Pulmonary hypertension was considered present if the velocity of the peak tricuspid regurgitation jet was ≥3 m/sec or the peak velocity of the flow across a ventricular septal defect or a patent ductus arteriosus suggested a systolic right ventricular pressure > 35 mm Hg or the eccentricity index was ≥1.15."

"Peak systolic and diastolic velocities had areas under the receiver operating characteristic curve of 0.89 (95% CI, 0.79-0.99) and 0.93 (95% CI, 0.85-0.99) for PVS, respectively, and a threshold velocity of 0.7 m/sec had sensitivity of 80% and 84% and specificity of 94%. There was no correlation between Doppler-derived pulmonary vein mean gradient and measured pulmonary vein mean gradient during cardiac catheterization in stenosed pulmonary veins."

Cut-off for peak "s" wave was 0.71 m/sec, or peak "d" wave of 0.68 m/s. 

Pulmonary vein stenosis in the context of BPD presentation by Alexandra Breton-Piette and Carolina Michel Macias

B-mode / Colour-Profile of the pulmonary veins and Doppler in pulmonary vein stenosis

PDA profile indicating some bidirectional shunt, mostly right to left - suprasystemic pulmonary pressures

A4C showing RV hypertrophy but preserved RV function (TDI showcasing systolic velocities)

TR jet with incomplete curve outlining that the sPAP is estimated at (at least) 117 mmHg

PSAX with a sweep outlining some bowing of the septum in systole