Clinical, Echocardiographic and Biomechanical Aspects of Coarctation of the Aorta in Infants in Latvia. Summary of the Doctoral Thesis

Abstract

The prevalence of congenital heart disease-coarctation of the aorta in neonates and small infants as well as the factors connected with morbidity and mortality of these patients in Lavia within years 2000-2010 were analyzed. The analysis of the echocardiographic findings prior to surgical correction of the coarctation and during medium term follow-up 70.7±33 months (minimum 20, maximum 131 months) was carried out. The results from the end of the study period were compared to the age matched control group. There were biomechanical experiments in vitro performed to investigate biomechanical properties of the native infantile aorta and surgically corrected infantile aorta with the use of such surgical techniques as anastomosis end-to-end, extended anastomosis end-to-end and left subclavian flap aortoplasty in the biomechanical part of the research. The prevalence of coarctation of the aorta in neonates in Latvia between 2000-2010 was 3.4±1.3 per 10.000 live births. Isolated coarctation was diagnosed more often on a later stage than aortic coarctation in combination with concomitant intra cardiac pathologies (p=0.029) that influenced patient`s preoperative condition. The survival for patients with isolated coarctation significantly exceeded the survival of the patients with concomitant intracardiac pathologies (p=0.001). There were more cases of prenatal diagnosis among the lethal cases that was connected with concomitant intracardiac pathology (p=0.01) as well as the patients with hypoplastic aortic arch (p=0.0001). Aortic recoarctation occurred in 25% of patients with no statistically significant differences dependent on the method of primary surgical correction (p=0.67). The patients with recoarctation of the aorta had left ventricle hypertrophy and decreased PWD doppler systolic/diastolic ratio in abdominal aorta normalizing after angioplasty. The biomechanical experiments showed a non-linear relationship between stress and strain in the infantile aorta, the modulus of elasticity of the aortic wall increased with increase of an inner pressure. Subclavian flap aortoplasty and elongated anastomosis end-to-end showed elastic properties closer to the native aorta but in cases of anastomosis end-to-end the stiffness did not change with the changes in inner pressure. The coarctation of the aorta should be looked on as a complicated cardio-vascular syndrome with a need for life-long follow-up due to the possibility of multiple modifiable complications in long term (recoarctation, arterial hypertension, formation of aneurysm). From the biomechanical point of view the subclacian flap aortoplasty has the biomechanical properties closer to the native aorta followed by extended anastomosis end-to-end, but anatomosis end-to-end significantly increases stiffness of the aortic wall. The surgical correction of the aortic coarctation remains gold standard for neonates and small infants with extended anastomosis end-to-end as the method of choice, but subclavian flap aortoplasty is still applicable in cases where the reconstruction of the aortic arch is otherwise impossible. The doctoral thesis is written in Latvian language. It consists of chapters: introduction, importance and novelty of the study, objective and the tasks of the study, review of literature, materials and methods, results, discussion, conclusions, practical recommendations, references, list of publications. The illustrative and statistical material is demonstrated in 27 figures and 22 tables, references include 169 publications of different authors.