Neurohormonal Activation, Oxygen Free Radicals, and Apoptosis in the Pathogenesis of Congestive Heart Failure:

An Overview of the Mechanism behind Excessive Volume of Pericardial Fat in Heart Failure

Heart failure (HF) is a clinical syndrome characterized by myocardial dysfunction leading to inefficient blood filling or ejection. Regardless of the etiology, various mechanisms, including adipokine hypersecretion, proinflammatory cytokines, stem cell proliferation, oxidative stress, hyperglycemic toxicity, and autonomic nervous system dysregulation in the pericardial fat (PCF), contribute to the development of HF. PCF has been directly associated with cardiovascular disease, and an increased PCF volume is associated with HF. The PCF acts as neuroendocrine tissue that is closely linked to myocardial function and acts as an energy reservoir. This review aims to summarize each mechanism associated with PCF in HF.

beta-blockade prevents sustained metalloproteinase activation and diastolic stiffening induced by angiotensin II combined with evolving cardiac dysfunction

Angiotensin II (Ang II)-mediated sympathostimulation may worsen the progression of cardiac failure, although the nature and mechanisms of such interactions are largely unknown. We previously demonstrated that Ang II combined with evolving cardiodepression (48-hour tachycardia pacing, 48hP) induces marked chamber stiffening and increases metalloproteinases (MMPs). Here, we test the hypothesis that both abnormalities stem from sympathostimulatory effects of Ang II. Forty-eight dogs were instrumented to serially assess conscious ventricular mechanics, MMP abundance and activity, and myocardial histopathology. 48hP combined with 5 days of Ang II (15+/-5 ng. kg(-1). min(-1) IV) more than doubled chamber stiffness (end-diastolic pressure >25 mm Hg, P<0.001), whereas stiffness was unchanged by Ang II or 48hP alone. In vitro and in situ zymography revealed increased MMP abundance and activity (principally 92-kDa gelatinase) from Ang II+48hP. Both stiffening and MMP changes were prevented by cotreatment with high-dose atenolol (which nearly fully inhibited isoproterenol-induced inotropy) but not partial beta-blockade. Myocellular damage with fibroblast/neutrophil infiltration from Ang II+48hP was also inhibited by high- but not low-dose atenolol, whereas collagen content was not elevated with either dose. These data support a role of sympathostimulation by Ang II in modulating myocardial MMP abundance and activity and diastolic stiffening in evolving heart failure and suggest a novel mechanism by which beta-blockade may limit chamber remodeling and diastolic dysfunction.