Experimental myocardial hypertrophy induced by a minimally invasive ascending aorta coarctation

Abstract

Ascending aorta coarctation was produced by a minimally invasive technique in rabbits. Animal mortality was 5%. Morphometric and hemodynamic parameters were evaluated. A parabiotically isolated heart model was used to assess the hemodynamic parameters. Left ventricular weight/body weight ratio and muscle area showed clear evidence of hypertrophy when compared to control. The hemodynamic changes in the isolated heart model suggested decreased diastolic and systolic function in the coarcted group. The present model produced hypertrophy with low mortality rates as a result of its less invasive nature. Key wordsExperimental models producing myocardial hypertrophy and ventricular dysfunction are of interest in heart research. These models permit the evaluation of drug effects, of myocardial protection methods, and of stunned myocardium recovery methods, among other possibilities. Several models have been proposed and different animals have been used. Several authors have described cardiac hypertrophy induced by drugs, coarctation of aorta or coarctation of the pulmonary artery (1-6). Aorta coarctation is frequently used in either the ascending or descending position. Ascending aorta coarctation is more similar to clinical conditions such as supravalvar congenital aortic stenosis. This technique, however, requires full sternotomy which is associated with up to 20% animal mortality (7,8). Minimally invasive methods are those which use small incisions by the endovascular technique or assisted video, and allow complex procedures to be carried out with less trauma (9). Our objective was to standardize a minimally invasive technique for ascending aorta coarctation in order to induce left ventricular anatomic and functional changes in rabbit hearts, with low surgical mortality.For the proposed technique, after sodium pentobarbital anesthesia, a small transverse cervical incision is made above the sternal bone. After retrosternal dissection, the ascending aorta and its branches are identified and, under pericardiotomy, aorta coarctation is carried out according to the classic technique of Bregagnollo et al. (4). This technique was applied to 10 animals and the results were compared with those for agematched, sham-operated rabbits (N = 10). After 5 weeks, the animals were euthanized

Proteção miocárdica ao coração hipertrofiado: o eterno desafio

“…From the histological standpoint, the alteration of the myocardial architecture involves hypertrophy and loss of myocytes, fibroblasts hyperplasia, and collagen deposition [20].…”

Efeitos das cardioplegias sangüínea e cristalóide no miocárdio hipertrófico de coelho: avaliação estrutural e ultra-estrutural

“…The aortic artery was identified, pericardiotomy was performed and the ascending aorta was isolated and coarctation was provoked using the technique described by Martins et al [16]. After 5 months with hypertrophic hearts (Figure 1), the animals were euthanized.…”

Experimental Cardiac Hypertrophy Induced by Oral Administration of Mineralocorticoid and Saline in Rats

“…8,9 Additionally, considering the multifactorial nature of hypertension and the heterogeneity of the experimental animals, each genetic hypertensive rat strain corresponds to specific variants. 10 Invasive-even the minimally invasive-techniques 11 of hypertrophy induction are frequently associated with high animal mortality, up to 20%.…”