The pulmonary valve regulates the blood flow of deoxygenated blood in the small circulatory system from the right ventricle into the pulmonary artery. In case of a malfunctioning pulmonary valve, there is strain on the right ventricle and the pulmonary circulation, which can be life-threatening in the long-term.

One in 100 children is born with a congenital heart defect. In one child out of ten, the pulmonary valve is either narrowed, leaking, or absent. Those valve abnormalities are often associated with other congenital malformations of the heart such as tetralogy of Fallot, ventricular septal defect, or transposition of the great arteries (TGA). Treatment of a non-functioning pulmonary valve may involve either cardiac catheterization with cardiovascular intervention or cardiac surgery.

However, because there is still no replacement valve that grows with the body, a new pulmonary valve must be replaced more frequently in children. How often do new interventions and operations occur, depending on the implant, timing, and type of intervention? The results of a first long-term study provide interesting answers to this question.

4,385 Cardiovascular Interventions and Cardiac Surgeries

For this purpose, researchers evaluated data from 1,000 participants of the National Registry who were treated in German pediatric cardiac centers between 1957 and 2018. Over a follow-up period averaging 24 years per patient, they were able to track the outcomes of 4,385 cardiovascular interventions and cardiac surgeries, as well as the use of nearly 2,000 pulmonary valve prostheses.

Timing and Type of Surgery are Crucial

The timing of the procedure plays a crucial role in the frequency of valve replacement. For example, the time interval to the next necessary pulmonary valve replacement was twice as long in patients who had their first valve replacement between the ages of one and ten, on average ten years, compared to those who had their first implantation during infancy.

In addition to age, the type of surgery also significantly influences the outcome: "Interestingly, the lengthening effect for pulmonary valves implanted by catheter was increased in all age groups that received their first valve replacement after the age of one," notes Dietmar Böthig, Senior Physician Clinical Research at the Department of Pediatric Cardiology and Pediatric Intensive Care Medicine at Hannover Medical School.

Age and Heart Defect Appropriate Valve Replacement

Each heart defect is unique and requires different pulmonary valve prostheses. In terms of durability, however, there are differences between the implants. The results of the study also indicate that not all of them are equally suitable for every age group.

In Infants

"When a valveless conduit or mechanical valve was used in infants, it took about five years to replace the valve in half of the patients. With a homograft, i.e. a human donor valve, on the other hand, it is eight years," explains Alexander Horke, head of the Department of Surgery of Congenital Heart Defects at the Clinic for Pediatric Cardiology and Pediatric Intensive Care Medicine at Hannover Medical School.

For Toddlers and Children

The picture was slightly different in toddlers and children between one and ten years of age: Here, in addition to homografts and Hancock valves with an average lifespan of twelve years and; mechanical valves with an average lifespan of 15 years were shown to be significantly more durable than Labcor, Carpentier-Edwards, and Matrix-P conduits in half of the patients. The latter required further valve replacement in half of the patients within five years.

In Ten- to 40-Plus-Year-olds

Homografts and mechanical valves were also clearly implanted the longest in ten- to 40-year-olds, while Labcor, Carpentier-Edwards, and Matrix-P having the shortest lifespans.

In patients past 40, Matrix-P conduits stood out with median durability of less than four years. After implantation of Contegra and Carpentier-Edwards conduits and homografts, the time to next valve replacement increased to 13 years in 80 percent of this age group.

For some valve types, however, the number of cases was small, Alexander Horke points out: "On the one hand, this limits the significance. On the other hand, this speaks for a good selection by the implanters. Basically, we were able to determine that Contegra conduits are more suitable for younger patients, while Hancock prostheses are more suitable for older patients."