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Heart Failure

Heart Failure. Dr. Meg- angela Christi M. Amores. The term "cardiac failure" means simply failure of the heart to pump enough blood to satisfy the needs of the body. Heart Failure. can result from any heart condition that reduces the ability of the heart to pump blood

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Heart Failure

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  1. Heart Failure Dr. Meg-angela Christi M. Amores

  2. The term "cardiac failure" means simply failure of the heart to pump enough blood to satisfy the needs of the body

  3. Heart Failure • can result from any heart condition that reduces the ability of the heart to pump blood • Usually due to: decreased contractility of the myocardium resulting from diminished coronary blood flow • Also caused by: damaged heart valves, external pressure around the heart, vitamin B deficiency, primary cardiac muscle disease

  4. Dynamics of the Circulation in Cardiac Failure • Acute Effects of Moderate Cardiac Failure • If heart is severely damaged, pumping ability of the heart is immediately depressed • 2 main effects: • Reduced cardiac output • damming of blood in the veins, resulting in increased venous pressure

  5. progressive changes in heart pumping effectiveness after MI • Top curve: normal Cardiac output • Point A is normal operating point • After heart is damaged, cardiac output curve immediately lowered • After seconds, new circulatory state is established (point B) • Only sustain for a few hours • Associated with fainting

  6. Compensation by Nervous Reflexes • When cardiac output falls precariously low, many circulatory reflexes become activated • Best known: BARORECEPTOR reflex • activated by diminished arterial pressure • Other reflexes: chemoreceptor reflex, the central nervous system ischemic response, and even reflexes that originate in the damaged heart • the heart, one way or another, becomes a stronger pump

  7. progressive changes in heart pumping effectiveness after MI • new circulatory state is depicted by point C • Showing a cardiac output of 4.2 L/min and a right atrial pressure of 5 mm Hg • With compensation

  8. Compensation by Nervous Reflexes • sympathetic reflexes become maximally developed in about 30 seconds

  9. Compensation by Fluid Retention • After the first few minutes of an acute heart attack, prolonged semi-chronic state begins: • retention of fluid by the kidneys • Varying degrees of recovery of the heart itself over a period of weeks to months • Renal Retention: no URINE output, until the cardiac output and arterial pressure rise • Thought to be detrimental

  10. Compensation by Fluid Retention • moderate increase in body fluid and blood volume is an important factor in helping to compensate • increases the mean systemic filling pressure • increases the pressure gradient for causing venous flow of blood toward the heart • it distends the veins • reduces the venous resistance • Excess fluid retention – no longer beneficial

  11. Detrimental Effects of severe fluid retention • (1) overstretching of the heart, thus weakening the heart still more • (2) filtration of fluid into the lungs, causing pulmonary edema and consequent deoxygenation of the blood • (3) development of extensive edema in most parts of the body

  12. progressive changes in heart pumping effectiveness after MI • After partial recovery, considerable fluid has been retained • state of the circulation is now changed from point C to point D • normal cardiac output of 5 L/min but right atrial pressure increased to 6 mm Hg

  13. SUMMARY • “Compensated Heart Failure” • (1) the instantaneous effect of the cardiac damage • (2) compensation by the sympathetic nervous system, which occurs mainly within the first 30 seconds to 1 minute • (3) chronic compensations resulting from partial heart recovery and renal retention of fluid

  14. Compensated Heart Failure • maximum pumping ability of the partly recovered heart is still half (LIME GREEN LINE) • increase in right atrial pressure can maintain the cardiac output at a normal level • Thus many people, especially older people, have normal resting cardiac outputs but ELEVATED BP

  15. Decompensated Heart Failure • heart becomes severely damaged • no amount of compensation, either by sympathetic nervous reflexes or by fluid retention can make the excessively weakened heart pump a normal cardiac output • Treated by: 1) strengthening the heart , (2) administering diuretic drugs to increase kidney excretion

  16. Unilateral Left Heart Failure • left side of the heart fails, blood continues to be pumped into the lungs , whereas it is not pumped adequately out of the lungs by the left heart • pulmonary vascular congestion and pulmonary edema • can cause death by suffocation in 20 to 30 minutes

  17. Cardiogenic shock • heart becomes incapable of contracting with sufficient force to pump enough blood into the peripheral arterial tree • always occurs when more than 40 per cent of the left ventricle is infarcted • death occurs in about 85 per cent of patients

  18. Edema in Heart Failure • Acute Heart failure does not cause EDEMA • Long-term Fluid retention by kidneys cause peripheral edema • 3 causes: • Decreased glomerular filtration • Activatin of renin-angiotensin system and increased reabsorption of water and salt • Increased aldosterone secretion

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