II. EFFECTS OF AGING ON THE HEART AND VASCULAR SYSTEM
A. Gross Anatomy
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.
B. 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 knowl¬edge will improve today’s unsatisfactory therapy for this condition.