Table.

Age-Associated Changes in the Heart

Functional changes Cardiac changes Diastolic dysfunction (decreased left ventricular diastolic compliance, impaired relaxation, reduced early diastolic filling, increased late diastolic filling) Increased left ventricular wall thickness Impaired left ventricular ejection and heart rate reserve capacity Altered heart rhythm (decreased heart rate variability, increased cardiac arrhythmias) Deficits in sympathetic modulation of heart rate and left ventricular contractility Prolongation of cardiac action potential Vascular changes Increased arterial stiffness Increased systolic arterial pressure, increased pulse pressure Endothelial dysfunction Histological and cellular changes Decrease in total number of cardiomyocytes (increased apoptosis and necrosis) Increased myocyte size (myocyte hypertrophy) Increased collagen content in the connective tissue of the heart Increased cardiac fibrosis Decreased No. of pacemaker cells Prolongation of cardiac action potential Reduced regenerative capacity and decline in number of cardiac stem cells Aortic wall thickness and arterial intimal thickening Molecular changes Blunted cardiac β-adrenergic response Decreased cardiac β receptors, decreased G-protein signaling Impaired calcium handling Impaired calcium pumping by SERCA2 Reduced expression and activity of SERCA2 Impaired mitochondrial function Accumulated mutations and deletions within mitochondrial DNA Increased accumulation of oxidative damage Mitochondrial loss Alterations in cardiac metabolism Decrease in myocardial fat utilization and oxidation TCA compromised, increased glycolysis Renin-angiotensin-aldosterone system activation Increased cardiac angiotensin II concentrations Reduced insulin/IGF signaling