Evaluation of experimental model of isolated chronic right ventricle failure / Avaliação de modelo experimental de falência crônica isolada do ventrículo direito

AUTOR(ES)

Petrônio Generoso Thomaz

DATA DE PUBLICAÇÃO

2007

RESUMO

Isolated chronic right ventricle (RV) dysfunction is difficult to achieve in experimental models, and sometimes very expensive. Some models require complex surgical procedures, with a high mortality rate and low reproducibility. In order to simulate the clinical status of RV failure, we have developed an experimental model of chronic RV failure by injecting local intramyocardial ethanol 96%. A severe RV dysfunction was induced in 13 mongrel dogs by means of multiple intramyocardial injections of ethanol 96% (total dose of 1ml/kg), in the inlet and trabecular portions of the RV. The hemodynamics, metabolic and ecocardiografic parameters were evaluated at baseline condition and after RV failure. The animals were followed for a 14-day period. After that, they were reoperated for pressure measurements, taken from femoral artery, left atrium (LA), right atrium (RA), RV and main pulmonary artery (PA). Blood flow was measured in the aorta (AO) and PA. Metabolic parameters were assessed simultaneously to pressure measurements, with arterial and venous blood samples withdrawn for gas and lactate analysis, and then, they were killed for morphological evaluation of the heart. All the animals were submitted to echocardiographic evaluation before the first operation, on sixth and on de 13th postoperative day. The mortality rate was 15,4% (2/13). There was a significant decrease in the pulmonary blood flow after RV failure induction (p=0,0018), as well as in the reoperation (p=0,002), as compared to baseline. This decrease in RV performance caused an increase in the venous lactate level, when baseline values are compared with pos infarction values (p=0,001) and reoperation (p=0003). The echocardiografic findings revealed an increased RV diastolic volume on the 6th (p=0,0001) and 13th postoperative day (p=0,0084), as compared to baseline values. Conversely, there was a significant decrease in the RV ejection fraction on the 6th and 13th postoperative day, when compared with baseline values (p=0,0001). Microscopic evaluation of RV samples showed transmural infarctions with histological characteristics aged of two weeks. Intra myocardial ethanol injection has allowed the creation of a simple, inexpensive and reproducible model of chronic RV failure. The hemodynamic, metabolic and echocardiographic parameters assessed in different moments of the protocol are compatible with severe RV failure. It may be useful for RV physiology studies of isolated right sided heart failure, as well as in the assessment of ventricular assist devices.

ASSUNTO(S)

ventricular dysfunction right heart failure congestive isquemia miocárdica / induzida quimicamente modelos animais. insuficiência cardíaca congestiva model animal. myocardial ischemia/chemically induced disfunção ventricular direita

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