Heart failure

By: Jesse Howe

Physiology of Heart FailureHeart function including entropy, the contractility of cardiac muscle, involves several molecular signal transduction pathways. A decrease in calcium released from the sarcoplasmic reticulum directly decreases entropy of the heart by impairing excitation contraction coupling, which is the contraction of a cardiomyocyte induced by an action potential from the senatorial node. Heart failure is characterized by a decrease in ejection fraction (the amount of blood pumped out of a ventricle for one beat of the heart) which is caused by a decrease in entropy. Changes in entropy result in significant transformations in the rate of force and pressure development within heart ventricles thereby altering the rate of ejection (Klabunde). The heart ventricles are visible in Figure 1 (below).The signal transduction pathways that innervate entropy are regulated by Ca2+. An increase in calcium increases entropy by sensitizing troponin-C to Ca2+ and a decrease in calcium decreases entropy resulting in heart failure.Troponin-C is one component of the troponin complex bound to tropomyocin bound to acting filaments in muscle (Klabunde).

Systolic Heart FailureDuring systolic heart failure there are two pathways by

which a loss of calcium may occur. One way includes poor signal transduction, affecting the amount of calcium initially released into the cell through the (long-lasting) L-type calcium channels. This consequently results in a decrease of Ca2+ released by the sarcoplasmic reticulum. The second pathway is caused by a loss of affinity of Troponin-C for Ca2+ resulting in poor muscle contraction (Klabunde). Diastolic Heart Failure

Diastolic Heart Failure

pressure overload caused by chronic high blood pressure or aortic valve problems

infiltrative cardiomyopathies, also called restrictive cardiomyopathy

pericarditis - inflammation of the sac around the outside of the heart normal aging can cause some DHF

chemotherapy for diseases like cancer genetic causes

ischemia - can be caused by CAD or by a chronic too-fast heart rate. Ischemia prevents the heart muscle from fully relaxing and increases heart stiffness. Chronic ischemia results in remodelling

-Obesity

-A diet high in saturated fats and cholesterol

-High blood pressure -Diabetes -Smoking

-Physical inactivity

Treatment for heartfailure;

What causes heart failure?A 19 year study of 13000 healthy adults in the United States (the National Health and Nutrition Examination Survey (NHANES I) found the following causes ranked by Population Attributable Risk score:

Ischemic Heart Disease 62%

Cigarette Smoking 16%

Hypertension(high blood pressure)10%

Obesity 8%

Diabetes 3%

Valvular Heart Disease 2% (much higher in older populations)

By; Jesse Howe