RENATO SAMY ASSAD
Projetos de Pesquisa
Unidades Organizacionais
Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina - Médico
LIM/11 - Laboratório de Cirurgia Cardiovascular e Fisiopatologia da Circulação, Hospital das Clínicas, Faculdade de Medicina
LIM/11 - Laboratório de Cirurgia Cardiovascular e Fisiopatologia da Circulação, Hospital das Clínicas, Faculdade de Medicina
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- Reversible pulmonary trunk banding: VII. Stress echocardiographic assessment of rapid ventricular hypertrophy in young goats(2013) FAVARO, Gustavo A. G.; ASSAD, Renato S.; ABDUCH, Maria C. D.; SILVA, Gustavo J. J.; GOMES, Guilherme S.; ANDRADE, Jose L.; KRIEGER, Jose E.; MOREIRA, Luiz Felipe P.Background: Ventricle retraining with abrupt systolic overload can cause myocardial edema and necrosis, followed by late ventricular failure. Intermittent systolic overload could minimize the inadequacy of conventional pulmonary artery banding. The present study compared ventricle function under dobutamine stress in 2 protocols of systolic overload in young goats. Methods: Nineteen young goats were divided into 3 groups: sham (n = 7; no systolic pressure overload), continuous (n = 6; systolic overload maintained for 96 hours), and intermittent (n = 6; 4 periods of 12-hour systolic overload, paired with a 12-hour resting period). Echocardiographic and hemodynamic evaluations were performed daily. The myocardial performance index and ejection fraction were evaluated at rest and during dobutamine stress. The goats were then killed for morphologic evaluation. Results: The intermittent group underwent less systolic overload than the continuous group (P <. 05). Nevertheless, both groups had increased right ventricular and septal masses compared with the sham group (P <. 0002). Echocardiography revealed a major increase in right ventricular wall thickness in the intermittent group (+64.8% +/- 23.37%) compared with the continuous group (+43.9% +/- 19.26%; P = .015). Only the continuous group remained with significant right ventricular dilation throughout the protocol (P <. 001). The intermittent group had a significantly better myocardial performance index at the end of the protocol, under resting and dobutamine infusion, compared with the continuous group (P <. 012). Conclusions: Both systolic overload protocols have induced rapid right ventricular hypertrophy. However, only the intermittent group had better preservation of right ventricular function at the end of the protocol, both at rest and during dobutamine infusion. (J Thorac Cardiovasc Surg 2013; 145:1345-51)
- Reversible pulmonary trunk banding. VI: Glucose-6-phosphate dehydrogenase activity in rapid ventricular hypertrophy in young goats(2011) ASSAD, Renato S.; ATIK, Fernando A.; OLIVEIRA, Fernanda S.; FONSECA-ALANIZ, Miriam H.; ABDUCH, Maria C. D.; SILVA, Gustavo J. J.; FAVARO, Gustavo G.; KRIEGER, Jose E.; STOLF, Noedir A. G.Objective: Increased myocardial glucose-6-phosphate dehydrogenase (G6PD) activity occurs in heart failure. This study compared G6PD activity in 2 protocols of right ventricle (RV) systolic overload in young goats. Methods: Twenty-seven goats were separated into 3 groups: sham (no overload), continuous (continuous systolic overload), and intermittent (four 12-hour periods of systolic overload paired with a 12-hour resting period). During a 96-hour protocol, systolic overload was adjusted to achieve a 0.7 RV/aortic pressure ratio. Echocardiographic and hemodynamic evaluations were performed before and after systolic overload every day postoperatively. After the study period, the animals were humanely killed for morphologic and G6PD tissue activity assessment. Results: A 92.1% and 46.5% increase occurred in RV and septal mass, respectively, in the intermittent group compared with the sham group; continuous systolic overload resulted in a 37.2% increase in septal mass. A worsening RV myocardial performance index occurred in the continuous group at 72 hours and 96 hours, compared with the sham (P <.039) and intermittent groups at the end of the protocol (P <.001). Compared with the sham group, RV G6PD activity was elevated 130.1% in the continuous group (P = .012) and 39.8% in the intermittent group (P = .764). Conclusions: Continuous systolic overload for ventricle retraining causes RV dysfunction and upregulation of myocardial G6PD activity, which can elevate levels of free radicals by NADPH oxidase, an important mechanism in the pathophysiology of heart failure. Intermittent systolic overload promotes a more efficient RV hypertrophy, with better preservation of myocardial performance and and less exposure to hypertrophic triggers. (J Thorac Cardiovasc Surg 2011;142:1108-13)
- Reversible pulmonary trunk banding. IX. G6PD activity of adult goat myocardium submitted to ventricular retraining(2013) ASSAD, Renato Samy; MIANA, Leonardo Augusto; FONSECA-ALANIZ, Miriam Helena; ABDUCH, Maria Cristina Donadio; SILVA, Gustavo Jose Justo da; OLIVEIRA, Fernanda Santos de; MOREIRA, Luiz Felipe Pinho; KRIEGER, Jose EduardoObjective: Increased glucose 6-phosphate dehydrogenase activity has been demonstrated in heart failure. This study sought to assess myocardial glucose 6-phosphate dehydrogenase activity in retraining of the subpulmonary ventricle of adult goats. Methods: Eighteen adult goats were divided into three groups: traditional (fixed banding), sham, and intermittent (adjustable banding, daily 12-hour systolic overload). Systolic overload (70% of systemic pressure) was maintained during a 4-week period. Right ventricle, pulmonary artery and aortic pressures were measured throughout the study. All animals were submitted to echocardiographic and hemodynamic evaluations throughout the protocol. After the study period, the animals were killed for morphological and glucose 6-phosphate dehydrogenase activity assessment. Results: A 55.7% and 36.7% increase occurred in the intermittent and traditional right ventricle masses, respectively, when compared with the sham group (P<0.05), despite less exposure of intermittent group to systolic overload. No significant changes were observed in myocardial water content in the 3 groups (P=0.27). A 37.2% increase was found in right ventricle wall thickness of intermittent group, compared to sham and traditional groups (P<0.05). Right ventricle glucose 6-phosphate dehydrogenase activity was elevated in the traditional group, when compared to sham and intermittent groups (P=0.05). Conclusion: Both study groups have developed similar right ventricle hypertrophy, regardless less systolic overload exposure of intermittent group. Traditional systolic overload for adult subpulmonary ventricle retraining causes upregulation of myocardial glucose 6-phosphate dehydrogenase activity. It may suggest that the undesirable ""pathologic systolic overload"" is influenced by activation of penthose pathway and cytosolic Nicotinamide adenine dinucleotide phosphate availability. This altered energy substrate metabolism can elevate levels of free radicals by Nicotinamide adenine dinucleotide phosphate oxidase, an important mechanism in the pathophysiology of heart failure.