Remodelamento cardíaco: análise seriada e índices de detecção precoce de disfunção ventricular

Abstract

Background: Supravalvar aortic stenosis (SVAS) is used to study overload-induced cardiac remodeling (CR). In this model, neither CR behavior since beginning stage nor the best parameters to identify ventricular dysfunction are clearly stated.Objective: ) Characterizing, early and evolutively, morphological and functional modifications during CR in rats with SVAS and ) identifying the most sensitive index for detecting the moment when the diastolic and systolic dysfunction first appeared in the left ventricle (LV). Methods IntroductionCardiac remodeling (CR) refers to an alteration in gene expression in response to an aggression, resulting in molecular changes, cellular changes and myocardial interstitial alterations, expressed in variations of the heart size, shape and function 1 . This is also a mechanism in adaptation to hemodynamic overload, allowing the heart to keep its functions in view of load increase 2-4 . This is deemed as a risk factor for development of ventricular dysfunction and heart failure (HF) 5 .Several experimental models have been proposed for the study of CR due to pressure overload, such as supravalvar aortic stenosis (SVAS) in rats [6][7][8] . When young animals are subject to aortic constriction, pressure overload is low at the beginning, being increased proportionally with their growth. SVAS advantages are: gradual development of CR, associated in short term to the improvement of systolic function; absence of severe lesions in myocardial anatomy; and low maintenance cost 9 . Around the 20 th week of SVAS, deterioration of systolic performance and HF [10][11][12][13] begin. This model is partially similar to SVAS in men 11 .Experiments in our lab with rats with SVAS assessed morphological and functional cardiac aspects, by means of echocardiogram (ECHO), in different periods of CR, finding out supranormal systolic function in 6 th or 8 th week 4,9,12 , diastolic dysfunction as of the 12nd week 9 and deterioration of systolic performance in the 21 st week. This last group of animals also had signs of heart failure 9 . Some authors, using hemodynamic evaluation, verified increase in left ventricular end-diastolic pressure after the 6 th week -in contrast, evaluation of diastolic function by means of ECHO has been found inaltered 13 . Litwin et al 8 assessed rats with SVAS by means of ECHO during 6 th , 12 th and 18 th weeks, and observed diastolic dysfunction as of the 6 th week and deterioration of systolic performance in the 18 th week.Analysis of mentioned studies has shows controversial results and absence of evaluation in an earlier post-induction of SVAS. The study aimed at characterizing, early and evolutively, Original ArticleArq Bras Cardiol 2010; 94(1) : 59-66

Paradoxical Sleep Deprivation Causes Cardiac Dysfunction and the Impairment Is Attenuated by Resistance Training

“…These results are similar to those observed in animals with supravalvular aortic stenosis [58]. The increase in the A wave probably culminates in a higher velocity of transmitral flow during the end diastole.…”

Importance of SERCA2a on early isolated diastolic dysfunction induced by supravalvular aortic stenosis in rats

“…The supravalvular AoS model is well established in scientific literature as a left ventricle (LV) hypertrophy promoter (3,4,19–24). It is defined by an initial light overload followed by a slow progression, proportional to the animal's growth.…”

“…All rats were submitted to echocardiographic evaluation 6 weeks after surgery, since previous studies have shown a diastolic dysfunction and improved systolic function progression from 2 to 6 weeks (3). A commercially available echocardiograph (General Electric Medical Systems, Vivid S6, Israel) equipped with a 5-11.5 MHz multi-frequency probe, was employed as previously described (26 –29).…”

“…Cardiac remodeling (CR) can be defined as changes in genetic expression, reflected in alterations in molecular, structural and functional characteristics, as a response to specific aggressions, such as ischemia, inflammation, genetic mutations and volumetric or pressure overload (1 –3). CR is time-dependent and in the long term it may be a threat, constituting an important risk factor for the development of ventricular dysfunction and heart failure (HF) (4).…”

Multivariate Analysis for Animal Selection in Experimental Research

“…Aortic stenosis was induced according to a previously described method 4 - 7 . The three- to four-week-old animals, weighing 70-90 g, underwent anesthesia with the association of ketamine chloride (60 mg/kg) and xylidine chloride (10 mg/kg), by intraperitoneal (ip) route.…”