The growth hormone (GH)/insulin-like growth factor 1 (IGF-1) axis regulates cardiac growth, stimulates myocardial contractility and influences the vascular system. The GH/IGF-1 axis controls intrinsic cardiac contractility by enhancing the intracellular calcium availability and regulating expression of contractile proteins; stimulates cardiac growth, by increasing protein synthesis; modifies systemic vascular resistance, by activating the nitric oxide system and regulating non-endothelial-dependent actions. The relationship between the GH/IGF-1 axis and the cardiovascular system has been extensively demonstrated in numerous experimental studies and confirmed by the cardiac derangements secondary to both GH excess and deficiency. Several years ago, a clinical non-blinded study showed, in seven patients with idiopathic dilated cardiomyopathy and chronic heart failure (CHF), a significant improvement in cardiac function and structure after three months of treatment with recombinant GH plus standard therapy for heart failure. More recent studies, including a small double-blind placebo-controlled study on GH effects on exercise tolerance and cardiopulmonary performance, have shown that GH benefits patients with CHF secondary to both ischemic and idiopathic dilated cardiomyopathy. However, conflicting results emerge from other placebo-controlled trials. These discordant findings may be explained by the degree of CHF-associated GH resistance. In conclusion, we believe that more clinical and experimental studies are necessary to exactly understand the mechanisms that determine the variable sensitivity to GH and its positive effects in the failing heart.

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Myocarditis is an inflammatory heart muscle disease, resulting from various etiologies, both noninfectious and infectious, which may be associated or not with cardiac dysfunction. Its course is unpredictable: it may spontaneously resolve or evolve into dilated cardiomyopathy and heart failure. A possible connection between myocarditis and dilated cardiomyopathy has long been postulated, but the intimate mechanisms linking these two conditions are still poorly understood. Viral myocarditis could induce a dilated cardiomyopathy through viral persistence and/or by triggering an autoimmune process. Understanding the mechanisms underlying the relationship between myocarditis and dilated cardiomyopathy will help in identifying an effective strategy of treatment aimed to stop and prevent cardiac damage. Specifically, we need to (a) evaluate the potential role of autoantibodies in disease prevention and progression, and understand their importance as markers of disease progression; (b) clarify the role of immunoregulation in exacerbating the disease.

NT-proBNP is useful in the assessment of the cardiac functional damage secondary to mitral and aortic regurgitation.

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