In Children, Double Lung Transplant Can Normalize Heart Function

Patricia Inacio, PhD avatar

by Patricia Inacio, PhD |

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A bilateral or double lung transplant can rescue heart function in children and adolescents with pulmonary hypertension (PH), a U.S. single-center study reports.

Specifically, a transplant was found to effectively normalize right ventricular (RV) function of the heart in PH patients up to age 21. Additionally, RV dysfunction prior to the transplant was not associated with worse outcomes among these children and teens.

These findings support double lung transplant for pediatric PH patients, according to researchers.

The study, “Recovery of right ventricular function after bilateral lung transplantation for pediatric pulmonary hypertension,” was published in the journal Pediatric Transplantation.

Although improved therapies over the last decades have greatly enhanced the survival of children with PH, in a subset of patients the disease continues to progress despite treatment. As a result of high blood pressure (hypertension) in the pulmonary arteries — a disease hallmark — the heart’s RV needs to work harder to pump blood. Continuous strain on the RV can cause thickening of the RV walls, and an increased risk of heart failure.

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Bilateral Lung Transplant Aids Children With Severe PAH and Heart Failure

A double lung transplant remains an important treatment option for patients with hard-to-treat PH and with significant RV dysfunction. In adults, several studies found that RV function was back to normal after patients received a lung transplant.

However, a similar outcome in children with PH has not been well characterized, according to the scientists. Also, how the level of RV dysfunction prior to the transplant may impact outcomes in pediatric patients requires further investigation.

To learn more, a team of researchers at Boston Children’s Hospital, in Massachusetts, reviewed the clinical data and outcomes of 23 patients PH with ages up to 21 who received a bilateral lung transplant between 2000 and 2020.

Patients were divided into two groups, those who showed RV dysfunction — a total of 14 patients, with a median age at surgery of 16.5 — and those with normal RV function before the transplant. That group comprised nine patients with a median age of 13.9 years at the time of surgery.

RV function was evaluated using the RV fractional area change (RVFAC), an ic (heart imaging) measurement that is used to identify pulmonary conditions. An RVFAC above 35% indicates normal RV function.

The left ventricular eccentricity index (LVEI), also analyzed with echocardiography, is a marker of RV pressure overload. Similar to RVFAC, it was assessed before and at regular periods — one, three, six and 12 months — after transplant.

The majority of patients with RV dysfunction had WHO Group 1 PH (11 of 14; 78%), while all of those with normal RV prior to the transplant had WHO Group 3 PH, with lung disease as the primary indication for a lung transplant. Group 1 includes PH tied to a narrowing of the small blood vessels in the lungs while Group 3 usually results from lung diseases or a shortage of oxygen in the body.

In the RV dysfunction group, pulmonary blood vessel widening treatments — ones using a vasodilator — before the transplant included parenteral (through a vein) prostacyclin (86%), phosphodiesterase 5 inhibitor (57%), and an endothelin receptor antagonist (14%).

The analysis revealed that RV function normalized within one year in all patients with RV dysfunction prior to lung transplant.

One year after the double lung transplant, the RVFAC was significantly higher, increasing from a mean of 24% before surgery to 43% post-transplant. Also, normalization of RV function was achieved in 70% of patients in the first three months after the transplant, and in all by 12 months, or one year. Results of LVEI also showed improvements after one year.

Those with normal RV function before the transplant retained it after one year.

Comparison of heart MRI scans before and after the transplant (available for six patients with RV dysfunction) confirmed the improvement in RV function. Data from five patients showed that RV ejection fraction — a measurement of how much blood is being pumped out of the heart — increased from a median of 31% to 64% after the transplant.

The median duration of ventilation, intensive care, and hospitalization showed no association with pre-transplant RV function.

After the transplant, no differences were seen between those with normal RV function and the group with RV dysfunction before surgery regarding parameters such as duration of ventilation and the need for mechanical circulatory support — a device that helps the heart pump out blood.

At one year of follow-up, 86% (12 of 14) of the RV dysfunction patients were alive. Six were alive two years later. Four patients eventually required a second lung transplant — these were done from 1.6 years to 9.8 years after the first transplant. All had normal RV function at the time of the second surgery.

Among the nine patients with normal RV function at the study start, six were alive at one year and five were alive at three years. One of these patients underwent a second lung transplant 1.7 years after the first transplant.

Respiratory failure was the cause of death in three patients — two in the RV dysfunction group and one with normal RV — and infections in the other three cases, also from both groups.

Overall, these results show that children and adolescents with PH and RV dysfunction were able to normalize their RV function after a double lung transplant.

Also, “pre-operative RV dysfunction was not associated with short-term clinical outcomes,” supporting the therapeutic potential of lung transplants in pediatric PH associated with RV dysfunction.