Is Smad3 the Key to Inflammation and Fibrosis in Hypertensive Heart Disease?

Abstract

Hypertensive heart disease (HHD) is characterized by myocardial remodeling not only in the left ventricle but also the left atrium and right ventricle. Clinically it is characterized by intact systolic function and diastolic dysfunction, which make up the major cause of congestive heart failure in the elderly, also termed “heart failure with preserved ejection fraction.” Hypertension is the major determinant for developing heart failure with preserved ejection fraction.1 As reviewed recently by Diez and Frohlich,2 most findings in hypertensive animals and patients demonstrate that HHD also results from pathological structural remodeling of the myocardium in response to a number of hemodynamic and nonhemodynamic factors altered in hypertension. HHD is histologically characterized by left ventricular hypertrophy, cardiac inflammation, and fibrosis. The histological characteristics of inflammation and fibrosis extend from the perivascular space into the intermuscular interstitium. The mismatch of excessive myocyte hypertrophy and disproportionate myocardial fibrosis leads to increased myocardial stiffness and impaired diastolic function in patients with chronic hypertension and heart failure with preserved ejection fraction. The activation of the renin-angiotensin (Ang) system (RAS) plays an important pathophysiological role in HHD and the development of myocardial inflammation and fibrosis. This is supported by the findings that blockade of the RAS, either with Ang-converting enzyme inhibitors or its type 1 receptor blockers, significantly improves cardiac function and regresses cardiac remodeling in patients with hypertension. …