The role of the renin-angiotensin-aldosterone system in heart failure.

Activity of the renin-angiotensin-aldosterone system (RAAS) is increased in patients with heart failure, and its maladaptive mechanisms may lead to adverse effects such as cardiac remodelling and sympathetic activation. Elevated renin activity has been demonstrated in patients with dilated cardiomyopathy. (Third- generation synthetic non-peptide renin inhibitors, with more favourable properties than earlier renin inhibitors, lower ambulatory blood pressure and may have a role to play in other cardiovascular disease.) Chymase, a protease inhibitor stored in mast cells that generates angiotensin II (Ang II) (in addition to angiotensin-converting enzyme [ACE]), has been linked to extracellular matrix remodelling in heart failure. Again, chymase inhibitors have been developed to investigate its functions in vitro and in vivo . Bradykinin is thought to contribute to the cardioprotective effect of ACE inhibition through modification of nitric oxide release, calcium handling and collagen accumulation. Ang II is believed to influence a number of molecular and structural changes in the heart, mostly mediated through the AT1-receptor. The importance of the RAAS in heart failure is shown by the survival benefit conferred by treatment with ACE inhibitors.