Medicine and Healthcare
New Pulmonary Valve
Which procedures and implants achieve the best results?
Scientific name of the study
Pulmonary valve prostheses: patient's lifetime procedure load and durability. Evaluation of the German National Register for Congenital Heart Defects
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.
Good to Know
The Large and the Small Circulatory System
The Large and the Small Circulatory System
In the large circulatory system (systemic circulation), the oxygenated blood collects in the left atrium. From here it is carried through the mitral valve into the left heart chamber. The chamber then pumps the blood through the aortic valve into the main artery (aorta). The aorta itself transports the blood through arteries, arterioles, and capillaries - blood vessels leading away from the heart – to the body and each somatic cell receives oxygen. During this phase of the circulatory system, the blood releases oxygen to the somatic cells of different organ and picks up carbon dioxide produced by all organs. The “used” deoxygenated blood is then taken to the right atrium of the heart by the venules, smaller and larger veins. In diastole the blood flows from the right atrium to the right heart chamber.
This is where the small circulatory system (pulmonary circulation) begins. During systole, the right heart chamber pumps the deoxygenated blood to the pulmonary artery. This happens simultaneously to the left heart chamber pumping the oxygenated blood to the aorta. The pulmonary artery branches out into smaller arteries and arterioles and, eventually, into capillaries. The capillaries cover the pulmonary alveoli like a delicate net. Within the pulmonary alveoli, gas exchange happens: The blood drops off carbon dioxide and picks up oxygen. The oxygenated blood flows through the pulmonary veins and into the left atrium. From here, the two blood circulations start anew.collapse
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.
Frequent Reoperations and Follow-up Operations Already in Adolescence
According to the study, the vast majority of those affected by pulmonary valve defects (90 percent) received their first valve prosthesis before the age of 27, 28 percent of whom received it during infancy. Reflecting the frequency of congenital heart defects by gender, the proportion of female patients was 45 percent.
In 46 percent of patients, only one valve replacement was performed. One third of the patients, in figures 332, needed a second and slightly more than one fifth of them, in figures 217, needed at least a third heart valve.
Valve Replacement after Five Years
After the first implantation in the first year of life, the first valve replacement takes place in half of the patients after about five years. Similarly, if the first valve is implanted between one and ten years of age, the next valve replacement takes place after ten years, and in the ten to 40-year-olds after 18 years. In the over-40s, who have a shorter follow-up time than the younger age groups, three quarters of the valves had not been replaced after twelve years. This also applies to pulmonary valves implanted by catheter intervention.
Three or More Heart Defect-Related Interventions
About 62 percent of patients also required three or more heart defect-related interventions. Seventeen percent of patients (166) experienced more than six and six percent of patients (58) even more than nine surgeries and interventions. On average, additional interventions were required every five to six years. This also showed that half of the patients required more than two surgeries or catheter interventions by the age of 15.
By the age of 30, half of the patients had already undergone cardiac surgery or interventions at least five times.collapse
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.
"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."
Scientific Details of the Study
Learn more about the study design, material and methods, as well as the background of the study:
Pulmonary valve prostheses: patient's lifetime procedure load and durability. Evaluation of the German National Register for Congenital Heart Defects.
Boethig D, Avsar M, Bauer UMM, Sarikouch S, Beerbaum P, Berger F, Cesnjevar R, Dähnert I, Dittrich S, Ewert P, Haverich A, Hörer J, Kostelka M, Photiadis J, Sandica E, Schubert S, Urban A, Bobylev D, Horke A, National Register For Congenital Heart Defects Investigators ,
Interactive cardiovascular and thoracic surgery 34, 2, 297-306, (2022). Show this publication on PubMed.