The pathophysiology of diastolic heart failure

Unfavorable left ventricular remodeling due to experience of chronic sleep restriction after myocardial infarction: The role of matrix metalloproteinases & oxidative stress

Disturbed sleep or sleep loss due to vocational or lifestyle changes following MI is a common problem that may affect many physiological processes involved in left ventricle (LV) remodeling. Herein, we proposed that experience of sleep disruption and/or restriction after myocardial infarction (MI) may aggravate cardiac extracellular matrix remodeling and induce apoptosis in the cardiomyocytes. MI was induced in adult male rats by permanent ligation of the left anterior descending coronary artery. Twenty-four hours after surgery, some animals experienced chronic sleep restriction (CSR) for 6 days. Serum levels of CK-MB, PAB, and TNF-α were evaluated at days 1, 8, and 21 postsurgery. Twenty-one days after surgery, hemodynamic parameters and expression of MMP-2, MMP-9, TIMP-1, and TNF-α, as well as myocardial fibrosis and apoptosis in the noninfarcted area of the LV were assessed. Our results showed a clear decrease in serum concentrations of CK-MB, PAB and TNF-α at day 21 postsurgery in the MI group as compared to MI+SR animals in which these markers remained at high levels. CSR following MI deteriorated LV hemodynamic indexes and also impaired the balance between MMPs and TIMP-1. Further, it yielded an increase in oxidant and inflammatory state which caused deleterious fibrotic and apoptotic effects on cardiomycytes. Our data suggest post-MI sleep loss may cause adverse LV remodeling due to increased inflammatory reactions as well as oxidative burden and/or anti-oxidative insufficiency that in turn impede the balance between MMPs and their inhibitors.

Pyruvate dehydrogenase as a therapeutic target for obesity cardiomyopathy

INTRODUCTION

Obesity cardiomyopathy is a major public health problem with few specific therapeutic options. Abnormal cardiac substrate metabolism with reduced pyruvate dehydrogenase (PDH) activity is associated with energetic and functional cardiac impairment and may be a therapeutic target.

AREAS COVERED

This review summarizes the changes to cardiac substrate and high energy phosphorus metabolism that occur in obesity and describes the links between abnormal metabolism and impairment of cardiac function. The available evidence for the currently available pharmacological options for selective metabolic therapy in obesity cardiomyopathy is reviewed.

EXPERT OPINION

Pharmacological restoration of PDH activity is in general associated with favourable effects upon cardiac substrate metabolism and function in both animal models and small scale human studies, supporting a potential role as a therapeutic target.

Proximal aortic compliance and diastolic function assessed by speckle tracking imaging

PURPOSE

Speckle tracking imaging (STI) is a recent technique that evaluates an echocardiographic image throughout the cardiac cycle and provides dynamic variables such as tissue velocities and strain rates. The objective of our study was to determine 1) if STI can be used to quantify proximal aortic compliance and 2) if decreased aortic compliance determined by STI will reproduce the previously reported correlation with diastolic function.

METHODS

This was a retrospective observational case series using previously obtained intraoperative transesophageal images. Diastolic performance was quantified by STI-based longitudinal velocities of the basal-septal and basal-lateral walls of the left ventricle in early diastole (LV E'). Change in proximal aortic volume was calculated using STI to measure peak longitudinal and radial velocities in early diastole. After normalizing for mean arterial pressure, compliance was calculated and then compared with basal-septal and basal-lateral LV E' using single regression analysis.

RESULTS

Twenty patients were included in our analysis. Linear regression of basal-septal LV E' and basal-lateral LV E' vs proximal aortic compliance during diastole each resulted in an R(2) value of 0.26 (P < 0.05).

CONCLUSION

Speckle tracking can be used to describe the physical motion of the aortic wall and to calculate its compliance. We confirm that variation in diastolic function can be attributed, in part, to aortic compliance. Our novel approach of measuring compliance throughout the cardiac cycle, isolating radial and longitudinal contributions, and evaluating previously obtained images retrospectively provides advantages over previously reported measures of aortic compliance. Speckle tracking promises new insights into ventricular function, aortic mechanics, and the interaction between these structures.