Aging causes decreased elasticity and compliance of the aorta and great arteries arterial stiffness. This results in higher systolic arterial pressures and increased impedance of the propagation of blood from the left ventricle through the arterial system and the delivery of blood to organs and tissues. Mild left ventricular hypertrophy also occurs.

Histological Changes

These changes in the heart muscle include decreased mitochondria and altered mitochondrial membranes. Increased collagen degeneration and interstitial fibrosis with increased lipid and amyloid deposition causes the left ventricular muscle mass to become stiffer. Because of this stiffness, after the systolic contraction of the ventricle it takes longer for the ventricular mass to relax in diastole. This defect in relaxation and an abnormal dispensability causes the ventricle to fail. Thus insufficient blood to meet the demands of the tissues is propelled into the arterial system and heart failure ensues. This condition is referred to as diastolic heart failure. The exact underlying causes for diastolic heart failure require further study. More knowledge will improve today’s unsatisfactory therapy for this condition.

Heart failure is commonly caused by systolic dysfunction of the ventricle. The ventricular muscle mass is weakened by scarring from heart attacks and other cardiac diseases. Failure of the muscle pump causes insufficient blood to be expelled from the ventricle into the arteries. Treatment for systolic heart failure has improved considerably since 2000.

Biochemical Changes

These changes include decreased protein elasticity, changes in enzyme content that affect metabolic pathways, decreased catecholamine synthesis, and diminished responsiveness to beta-adrenergic stimulation.

Electrical Conduction System

Substantial loss of pacemaker cells in the sinus node cause a fall in heart rate and finally failure. This condition is called sick sinus syndrome and is the most common reason for implanting an electronic pacemaker. Increased fibrosis and calcification of the conduction system and loss of specialized cells in the His bundle and bundle branches can result in failure of the electrical impulse to reach the ventricles. This condition is called heart block and requires a pacemaker.

Valvular Changes

These changes include fibrosis, thickening and calcification of heart valves which leads to degenerative valvular disease. Calcified aortic stenosis may require valve surgery but the statins, cholesterol-lowering agents, have been shown to decrease the rate of stenosis and may delay surgical intervention. Mitral annular calcification occurs commonly and occasionally causes mitral regurgitation, atrial arrhythmia, heart block, and infective endocurditis. Fibroproliferative lesions producing mitral regurgitation has occured in elderly patients treated with antiparkinsonian dopamine receptor agonist pergolide.