Intraluminal Pulmonary Vein Stenosis in Children: A “New” Lesion.
This article discusses intraluminal pulmonary vein stenosis (PVS) in children, a rare disorder that leads to progressive narrowing of the extrapulmonary veins and is associated with a high mortality of up to 50%. PVS is a neuroproliferative process with fibroblast and myofibroblast proliferation and matrix deposition within the pulmonary vein walls producing a thickened intima. It has relentless progression. The causes are 3-fold:
- Primary or congenital, native or isolated and is seen in children with normally connected pulmonary veins and no intracardiac defects
- PVS associated with congenital heart disease (HLHS, conotruncal abnormalities and anomalous pulmonary vein connections). It is most commonly seen following TAPVC repairs and increased flow through the pulmonary veins may potentiate the risk.
- PVS associated with prematurity especially those less than 26 weeks gestation, with bronchopulmonary dysplasia, NEC, and retinopathy of prematurity. These babies may have L to R shunts (ASD or PDA). They may also have required mechanical ventilation where its need and duration increase the risk.
It is associated with Smith-Lemli-Opitz (autosomal recessive disorder of cholesterol metabolism) and Down syndromes where the progression of PVS and pulmonary hypertension is more aggressive.
Cardiac catheterisation and pulmonary vein angiography remain the gold standard for diagnosis. Other imaging modalities include transesophageal and transthoracic echocardiography, MRI, CT angiography and radionuclide lung scans.
Mortality predictors include involvement of 3 or more pulmonary veins, bilateral pulmonary vein involvement, onset of PVS in infancy, increased pulmonary artery pressure, RV dysfunction, restenosis after surgery, distal/upstream disease and the progression to veins not initially involved.
Treatments include medical and surgical therapies. Drug therapies including imatinib mesylate and bevacizumab which target cell surface proteins of platelet derived growth factor and the vascular endothelial growth factor receptor have been used. These have been better tolerated than the older drug treatments of vinblastine and methotrexate. These newer treatments have been used in conjunction with catheter and surgical interventions. Patients are more likely to experience PONV if on imatinib and bevacizumab. The use of losartan is currently being explored. Cardiac catheterization assesses both hemodynamics and anatomy and allows balloon and cutting balloon angioplasty, cryoballoon angioplasty and stent implantations. These are high risk procedures with a 7.6% incidence of post procedure stroke. Surgery is also used, ideally with suture less repairs.
Anaesthesia is challenging in these patients. The anaesthesia management for these high-risk procedures is downplayed. The authors recommend knowing RV and tricuspid valve function and pulmonary artery pressures. They recommend aggressive blood pressure maintenance to support RV coronary perfusion and avoiding bradycardia. They recommend considering the use of all inotropes, recognising the ideal combination of agents has not been determined and all have been used successfully. For the group of patients responsive to nitric oxide, this can be started at induction. They suggest avoiding an increase in PVR due to hypoxia, hypercarbia, acidosis, increased sympathetic tone, vasoconstrictor agents, pain and cold. They suggest using premedication (ketamine and midazolam), IV insertion, low dose volatile, fentanyl and muscle relaxation. They commence dopamine at induction. After instrumenting and occluding the pulmonary veins, pulmonary edema development is not uncommon and pulmonary hemorrhage may occur requiring postoperative ventilation. Edema can be treated with diuretics and PEEP. In the event of cardiovascular collapse during catheter procedures, this centre has not utilised ECMO.
Reviewed by: Fiona Macfarlaine