Cardiac failure

cardiac (heart) physiology

1. Cardiac Failure Prof. Dr. Rashid Mahmood

2. Lesson Contents Dynamics of the Circulation in Cardiac Failure Unilateral Left Heart Failure Low-Output Cardiac Failure-Cardiogenic Shock Edema in Patients with Cardiac Failure Cardiac Reserve

3. Definition: The term cardiac failure means that the heart is unable to pump sufficient blood to satisfy the metabolic demands. That results in under-perfusion which causes fluid retention and increased blood volume

4. Types (Classifications of Cardiac Failure) Based on stage/severity/ compensation Compensated Decompensated Based on side of heart involved Left heart failure Right heart failure Bilateral heart failure Based on cardiac output Low-output cardiac failure High-output cardiac failure Based on duration Acute heart failure Chronic heart failure Based on type of function affected Systolic heart failure Diastolic heart failure

5. Acute Effects of Moderate Cardiac Failure Cardiac Failure ↓ cardiac output damming of blood in the veins ↑ increased venous pressure

6. Compensation tone of blood vessels ↑ mean systemic filling pressure  

7. Chronic Stage of Failure Fluid Retention Moderate Fluid Retention Excess Fluid Retention Beneficial Detrimental Effects overstretching of heart pulmonary edema edema

8. Q.1 Name any two compensatory mechanisms for low cardiac output

9. 1. Cardiac Failure based on stage/severity/ compensation Compensated Decompensated

10. Compensated Heart Failure 1 2 3

11. Compensated heart failure: shift of Frank-Starling Curve downwards and to the right in a failing heart

12. Progressive changes in cardiac output after acute myocardial infarction ( Compensated Heart Failure)

13. Decompensated Heart Failure 2 3 4 5 1

14. Decompensated heart disease showing progressive shift of the venous return curve to the right as a result of continued fluid retention

15. Greatly depressed cardiac output that indicates decompensated heart disease

16. Effect of digitalis in elevating cardiac output curve leading to increased urine output and progressive shift of venous return curve to left

17. Q.2 How does sympathetic stimulation compensate low cardiac output ?

18. 2. Cardiac Failure based on side of heart involved Left heart failure Right heart failure Bilateral heart failure

19. Unilateral heart failure ↑ Mean pulmonary filling pressure Pulmonary edema (Rapid) ↑ Mean systemic filling pressure Peripheral edema (Congestive Cardiac Failure) (Slow) Left heart failure Right heart failure

20. Mechanism of Slow Peripheral edema in Cardiac Failure S evere acute cardiac failure often causes a fall in peripheral capillary pressure rather than a rise

21.   C auses of reduced renal output of urine in heart failure ( Long-Term Fluid Retention ) Decreased glomerular filtration Activation of the renin-angiotensin system and increased reabsorption of water and salt by the renal tubules Increased aldosterone secretion Stimulation of ADH Activation of sympathetic nervous system Decreased glomerular filtration rate Increased reabsorption of salt and water Stimulation of renin release and angiotensin II formation Stimulation of ADH

22. Cardiac Reserve The maximum percentage that the cardiac output can increase above normal 300 to 400 percent In athletically trained person 500 to 600 percent or more It decreases with all type of heart failure

23. Cardiac Reserve in different conditions

24. Q.3 Define cardiac reserve.

25. 3. Cardiac Failure based on cardiac output Low-output cardiac failure Ischemic heart disease Cardiomyopathies High-output cardiac failure

26. Low-Output Cardiac Failure-Cardiogenic Shock Vicious Circle of Cardiac Deterioration in Cardiogenic Shock

27. High Cardiac output conditions

28. 4. Cardiac Failure based on duration Acute heart failure Left heart failure Myocardial infraction Chronic heart failure Congestive heart failure

29. 5. Cardiac Failure based on type of Function affected Systolic heart failure Weak ventricular contraction ↓ stroke volume ↓ ejection fraction Diastolic heart failure ↓ elasticity of myocardium ↓ filling during diastole Ejection fraction initially maintain Heart failure with preserved ejection fraction

30. Q.4 How much is normal ejection fraction? In which type of heart failure it is relatively normal?

31. Take Home points (1/3) Inability of the heart to pump sufficient blood to satisfy the metabolic demands is called cardiac failure (Heart Failure) There are diffident Types of Classifications of Cardiac Failure Cardiac Failure leads to ↑ increased venous pressure and Fluid Retention Body Compensatory mechanisms may bring back cardiac output to normal resting value ( Compensated Heart Failure ), in mild to moderate heart failure

32. Take Home points (2/3 ) Chronic Stage of Failure results in pulmonary edema , peripheral edema, cardiac insufficiency . In Decompensated Heart Failure , h omeostatic mechanisms of the body are unable to bring back the cardiac output to minimum normal value, and the condition of the patients deteriorates, ending in death , if not treated. Left heart failure leads to Pulmonary edema , that may develop Rapidly . Right heart failure leads to Peripheral edema , that develops Slowly . Right heart failure is commonly called Congestive Cardiac Failure

33. Take Home points(3/3 ) Long-Term Fluid Retention due to compensatory mechanisms are the major cause increased preload . Cardiac Reserve , i.e. the maximum percentage that the cardiac output can increase above normal, decreases in cardiac failure High- cardiac output conditions may ultimately lead to cardiac failure Vicious Circle of Cardiac Deterioration results in Cardiogenic Shock In Systolic heart failure there is ↓ ejection fraction In Diastolic Heart failure ejection fraction remains preserved initially