Biomechanical Properties of Coronary Arteries Neonates: Preliminary Results

One of the most important issues in pediatric cardiac surgery is myocardial protection when a cardioplegic solution mixed with oxygenated blood is injected into coronary arteries with a pump. In this case, it is necessary to establish the right pressure of the cardioplegic solution in coronary arteries taking into account their biomechanical properties. Biomechanical properties of eight specimens of coronary arteries from neonates 12.3 ± 13.7 days old and weight 4.1 ± 0.9 kg were investigated and compared with adult arteries. Specimens were pressurized from 0 to 200 mmHg in steps of 20 mmHg while maintaining the length of the sample in situ. We observed that the relationship between stress and strain in neonates was non-linear. There was a rapid increase of strain until the inner pressure reaches 80–100 mmHg and not as rapid regarding to the stress in the arterial wall. When the internal pressure exceeds 100 mmHg the strain of the arterial wall increases much slower but at the same time the wall stress and modulus of elasticity begin to increase rapidly. It means that the structural elements of the arterial wall have been straightened and possible damage in the wall of coronary arteries of neonates may appear. These results were compared with biomechanical properties of arterial walls of adults and differences had been found. Our first experimental results show that the pressure of the cardioplegic solution in neonatal coronary arteries should not exceed 100 mmHg to decrease the risk of structural damage of the vascular wall.