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Cardiac Failure BS 4th Semester Arsalan Yousuf Heart Failure or Congestive Heart Failure Failure of the heart to pump enough blood to satisfy the needs of the body. CAUSES • Decreased contractility of the myocardium resulting from diminished coronary blood flow. • Damaged heart valves, • External pressure around the heart, • Vitamin B deficiency, • Primary cardiac muscle disease etc. Congestive heart failure is a syndrome that can be caused by multiple underlying diseases such as: • • • • • • • • • • • • Congenital heart disease Atherosclerosis Rheumatic fever Cardiomyopathy Valve disorders Ventricular failure Left or right-sided failure Hypertension Prolonged alcohol or drug addiction Previous heart attack Diabetes Chronic rapid heartbeats Common Terminologies Cardiac Arrest (cardiopulmonary arrest) is the cessation of normal circulation of the blood due to failure of the heart to contract effectively. Heart Attack (myocardial infarction) results from the interruption of blood supply to a part of the heart, causing heart cells to die. Cardiomyopathy (heart muscle disease) is the measurable deterioration of the function of the cardiomyocyte and myocardium for any reason. Acute Effects of Cardiac Failure As a result of any damaged condition two main effects occur: •Reduced cardiac output •Damming of blood in the veins, resulting in increased venous pressure. Compensation for Acute Cardiac Failure by Sympathetic and Parasympathetic Nervous System Parasympathetic Nerves Releases acetylcholine Decreases heart rhythm and excitability. Excitatory signals are no longer transmitted into the ventricles. Increased permeability of the fiber membranes to potassium ions Sympathetic Nerves Releases norepinephrine at sympathetic endings. Increases the rate of sinus nodal discharge. Increases the overall heart activity. Increases the permeability of Na+ and Ca2+ ions. Fluid Retention Helps to Compensate Cardiac Output After few minutes of an acute heart attack, a prolonged semi-chronic state begins, characterized mainly by two events: (1) retention of fluid by the kidneys. (2) varying degrees of recovery of the heart itself. Helps to increases the pressure gradient for causing venous flow of blood toward the heart. Decompensated Heart Failure Main cause of decompensated heart failure is failure of the heart to pump sufficient blood to make the kidneys excrete daily the necessary amounts of fluid. Heart condition continues to worsen. EDEMA Abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling. Treatment of Decompensation. • Strengthening the heart by administration of a cardiotonic drug, such as digitalis • Administering diuretic drugs to increase kidney excretion while at the same time reducing water and salt intake. Unilateral Left Heart Failure In patients with early acute failure, leftsided failure predominates over rightsided failure • Blood continues to be pumped into the lungs with usual right heart vigor. • Not pumped adequately out of the lungs by the left heart into the systemic circulation. • The mean pulmonary filling pressure rises because of shift of large volumes of blood from the systemic circulation into the pulmonary circulation. • Fluid begins to filter out of the capillaries into the lung interstitial spaces and alveoli, resulting in PULMONARY EDEMA. Peripheral Edema Left or right heart failure is very slow to cause peripheral edema. When a healthy heart acutely fails as a pump, the aortic pressure falls and the right atrial pressure rises. Severe acute cardiac failure often causes a fall in peripheral capillary pressure rather than a rise. Fluid Retention by the Kidneys – As a result of Peripheral Edema Peripheral edema begin to occur because of fluid retention by the kidneys. • This elevates the right atrial pressure to a still higher value and returns the arterial pressure back toward normal. • The capillary pressure now also rises markedly, thus causing loss of fluid into the tissues and development of severe edema. • Decreased glomerular filtration • Activation of the renin-angiotensin system • Increased aldosterone secretion. Cardiogenic Shock Circulatory shock syndrome caused by inadequate cardiac pumping is called cardiogenic shock or simply cardiac shock. • The survival rate is often less than 15 percent. • Vicious circle of cardiac deterioration. • Immediate administration of digitalis is often used for strengthening the heart. Cardiac Reserve The maximum percentage that the cardiac output can increase above normal is called the cardiac reserve.