Heart failure is commonly caused by systolic dysfunc¬tion 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 consider¬ably since 2000.
C. 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.
D. 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. (See the chapter Pacemakers.)
E. 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 com¬monly and occasionally causes mitral regurgitation, atrial arrhythmia, heart block, and infective endocurditis.

Страницы: 1 | 2 | 3