Bilateral Lung Transplant Aids Children With Severe PAH and Heart Failure
Bilateral lung transplant rapidly and effectively normalizes right ventricular function of the heart in children with severe pulmonary arterial hypertension (PAH) and heart failure, a study reports.
These benefits in the 15 children evaluated were also independent of a child’s age, weight, and right ventricular (RV) impairment before the transplant.
Given the observed recovery in heart function within two months of the surgery, these findings support bilateral lung transplant as a “preferred” option to the more complex and harder-to-obtain heart-lung transplant, even in children with end-stage PAH, the researchers noted.
PAH’s hallmark pulmonary artery narrowing restricts blood flow across the lungs, raising blood pressure (hypertension) and making the right ventricle of the heart work harder to pump blood. Continuous strain on the right ventricle can cause thickening of the RV walls, ultimately leading to heart failure.
As such, and despite recent improvements in treatments and patient survival, “bilateral lung transplantation (LuTx) or combined heart-lung-Tx (HLTx) remains the only established treatment option for patients with end-stage PAH,” the researchers wrote.
Whether and how quickly RV function recovers after bilateral lung transplant in children with severe PAH and heart failure, however, remains largely unclear.
A team of researchers in Germany evaluated RV-related parameters in 15 children (12 girls and three boys) with severe PAH and RV failure who received a bilateral lung transplant.
Patients, with ages ranging from 1.9 to 17.6 years, underwent the surgery at Hannover Medical School between December 2013 and January 2021. Nine (60%) were younger than 12 years old at the time of surgery.
Their heart health was assessed with advanced echocardiography (Echo) and heart MRI before surgery and about six weeks (1.5 months) after it. Heart MRI could not be performed in nine children, due to the need for general anesthesia or poor health.
At up to seven years of follow-up, all the children were alive. They all showed a “rapid and full recovery” of RV systolic (contractile) function and a significant reduction in RV wall thickening.
These benefits were observed regardless of age, weight, and severity of RV dysfunction before surgery.
Particularly, RV ejection fraction — the amount of blood that is pumped out with each contraction — rose significantly from 30% to 63%, reflecting a complete normalization of RV systolic function following the lung transplant.
The children also showed significant improvements in right ventricle/left ventricle (RV/LV) end-systolic diameter ratios, a measure of RV abnormal enlargement, and RV longitudinal contractility, as assessed with both Echo and MRI.
However, right ventricle thickening persisted beyond two months, as assessed by non-invasive imaging and electrogardiogram.
Notably, both Echo- and MRI-based RV/LV end-systolic diameter ratios were found to be excellent diagnostic tools to assess RV dysfunction, being superior to tricuspid annular plane systolic excursion (TAPSE). TAPSE is an Echo measure commonly used to assess right ventricular systolic function.
These findings highlighted that “RV volumes and systolic RV function completely normalize” six weeks after bilateral lung transplant, “even in children with severe RV failure,” the researchers wrote.
Given the shortage of heart-lung block organs in North America and Europe, the greater surgical complexity of heart-lung transplant, and the rapid recovery of RV function observed in this study, bilateral lung transplant “should be preferred over heart-lung transplantation,” even in “end-stage pediatric PAH with poor RV function and low cardiac output,” the team added.
Moreover, “easily obtainable RV/LV end-systolic ratios and echocardiographic 2D RV longitudinal strain can likely track clinical improvement in pediatric PAH and may provide valuable prognostic information beyond LuTx, for example, the response to add-on PAH-targeted pharmacotherapy,” the researchers concluded.