Heart transplant given to children in cardiac failure may resolve PH

Pulmonary hypertension common in young patients with heart failure

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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A heart transplant may resolve the pulmonary hypertension (PH) often found in children with heart failure — the organ’s inability to pump enough blood to meet the body’s needs, a small study found.

After the transplant, however, it took longer for blood pressure to normalize in children with congenital heart disease, which is present from birth, than in those with cardiomyopathy, a disease of the heart muscle.

Understanding how quickly PH resolves can help doctors in determining how well a child will do after a heart transplant, including a likely need for breathing support or other treatments.

The study, “Pulmonary hemodynamics before and after pediatric heart transplantation,” was published in the journal Clinical Transplantation by a team of researchers in Switzerland.

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Pulmonary hypertension found in majority of study’s 23 children

Chronic, or long lasting, heart failure can increase pressure in the pulmonary (lung) blood vessels due to the heart being unable to efficiently carry blood from the lungs and to the rest of the body.

Over time, abnormal blood vessel remodeling — changes in the vessels’ structure — can cause them to become thick and resistant to blood flow, resulting in fixed high blood pressure that “may limit the outcome of pediatric heart transplantation.”

A review of the medical records of 23 children (15 girls, eight boys), given or prepared for a heart transplant at University Children’s Hospital Zurich from 2005 to 2019, showed a mean pulmonary arterial pressure (PAP) before surgery of 26 millimeters of mercury (mm Hg). The range was 18.5 to 30 mm Hg.

Thirteen of the children (56.5%) met the criterion for PH, defined as a mean PAP higher than 20 mmHg in children older than 3 months, and 11 had a mean PAP higher than 25 mm Hg.

Their median age at surgery was 3.9 years, ranging from nearly 11 months to 8.2 years. The most common indication for a heart transplant was cardiomyopathy (73.9%), followed by congenital heart disease (21.7%). One child had a tumor in the heart.

Decline in pulmonary hypertension quicker in children with cardiomyopathy

Two weeks after surgery, their mean PAP decreased to 20.5 mmHg. Pulmonary capillary wedge pressure, an indirect measure of pressure in the heart’s left top chamber, which receives oxygen-rich blood from the lungs, also dropped significantly from 19 to 14.5 mm Hg.

At a median of 4.2 years after surgery, their mean PAP had decreased to 19.5 mm Hg and pulmonary capillary wedge pressure to 12.8 mmHg. Pulmonary vascular resistance also dropped from 2.65 to 1.58 Wood units per square meter.

A gradual decline in mean PAP values after a transplant was seen in children with cardiomyopathy. Their mean PAP before surgery was 25.1 mm Hg, and 18.3 mm Hg at the last follow-up.

In contrast, children with congenital heart disease experienced an initial increase in mean PAP, from 21.4 to 31.6 mm Hg two weeks after surgery. It then decreased gradually to 22.6 mm Hg at the last follow-up.

Elevated mean PAP after surgery was linked to prolonged  intensive care stays, and children with congenital heart disease were placed on a ventilator to help with breathing for a mean 10 days longer than children with cardiomyopathy (12 vs. two days).

Three children died, 21 days to 7.8 years after the heart transplant, and PH was not considered the cause of these deaths.

“While PH before pHTx [pediatric heart transplant] is frequent, after pHTx the normalization of PH starts immediately in [cardiomyopathy] patients but is delayed in [congenital heart disease] patients,” the researchers concluded.

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