Realce tardio e perfusão miocárdica em cardiomiopatia hipertrófica (comparação entre grupos)

Abstract

SummaryBackground: The magnetic resonance imaging (MRI) is an effective method to study hypertrophic cardiomyopathy (HCM).Objective: To evaluate, using MRI, the parameters of systolic function, perfusion and myocardial viability in patients with HCM, comparing the groups with and without obstruction of the left ventricular outflow tract.Methods: Twenty-one patients with a diagnosis of HCM underwent the assessment of myocardial function, viability and perfusion under stress and at rest through MRI.Results: The ventricular segments most severely impaired by hypertrophy were those of the septal region. The obstructive group presented segmental myocardial thickening distribution similar to the non-obstructive group, but with higher means than the first group. The mean ejection fraction of the patients in the obstructive group was higher than in the non-obstructive group, whereas the means of the end systolic and diastolic volumes were lower in the obstructive group. There was a positive correlation between the ventricular segmental thickening and the late enhancement segmental mass. The stress induction resulted in an increase in the number of segments with perfusion alterations and this alteration was more evident in the obstructive group. Conclusion

Association between Functional Variables and Heart Failure after Myocardial Infarction in Rats

“…Finally, it is already well-established that the major determinant of ventricular function, of the remodeling process and, consequently, of heart failure onset in this model, is the size of the infarction. 4 , 26 , 28 , 29 In our study, however the difference in infarction size among animals with and without heart failure, although significant, was low (43 ± 7% vs. 40 ± 8%, respectively). Therefore, we conclude that other factors rather than the infarction size, are important determinants of heart failure onset in this model.…”

“…The diagnosis of heart failure was made by thrombus detection in the left atrium, pleural effusion, ascites, and right ventricular hypertrophy, characterized by the ratio of the right ventricle weight adjusted for body weight > 0.8 mg/g, as previously described. 4 , 26 , 27 …”

“…The most important factor, however, refers to the similarity with the physiopathological changes that occur after an infarction in humans. 4 …”

Quantitation of Acute Necrosis After Experimental Myocardial Infarction

“…The extent of necrosis after MI is linked to the duration of ischemia and also to the size of the area at risk (AAR), which is the region of tissue that relies on perfusion downstream of the arterial blockage. Location of blockage affects infarct size; in rodents, ligation of the left anterior descending (LAD) artery proximal to its origin can create an infarction consisting of >65 % of the left ventricle with a mortality rate of 100 % [2]. In humans, proximal LAD occlusions are associated with a greater extent of necrosis and a less favorable prognosis [3].…”

“…Experimental mice are naturally less susceptible to both atherosclerosis and MI, and therefore genetic and surgical means have been devised to, in a controlled fashion, model the physiology, histology, and cell biology of human MI [2]. In patients, MI often manifests at the left ventricle and/or ventricular septum, with isolated right ventricle infarcts occurring in the minority of cases [6].…”