Heart Failure Flashcards
Heart failure
inability of the heart to pump blood at the required rates for normal metabolic activity
inability of the heart to only pump bloods at an elevated filling pressure
Mechanisms of cardiac dysfunction
Pump failure obstruction to flow regurgitant flow conduction defects compromised ventricular filling obligatory high output states Loss of continuation of the circulatory system Any severe cardiac disease
Pump failure
damaged muscle (IHD)
Intrinsic contractile failure is ( dilated cardiomyopathy)
Obstruction to flow
Overwork of the chamber proximal to the obstruction ( HPT, Aortic mitral stenosis ..)
Regurgitant flow
Volume overload (mitral and aortic incompetence)
Conduction defects
Uncoordinated generation or blockage of cardiac impulses
non-uniform and inefficient contraction of the myocardium ( heart block, v. Fibrillation)
Obligatory high output states
Increased work of the heart ( anemia…)
Loss of continuation of the circulatory system
Allows escape of blood (rupture of myocardium aneurysm)
Factors affecting features of cardiac failure
Age
Speed of onset
presence of other systemic disease
Types of cardiac failure
Acute failure chronic failure low output failure High output failure forwards failure backward failure systolic failure Diastolic failure
Acute failure
Due to sudden loss of contractility ( MI) or sudden overload (regurgitation due to valve rupture )
Chronic failure
Over a period of years (HPT..)
After an episode of acute failure
Low output failure
failure of the heart to pump normally
Cardiac output fails to increase or decline during exercise , or decline during rest
High output failure
Cardiac failure even if cardiac output is normal or elevated
Due to either blood volume increase, increased venous return , decreased peripheral resistance
come with tachycardia and Gallop rhythm
Forward failure
Diminished CO
Backwards failure
Damming back of blood in venous system
Systolic failure
Systolic ventricular dysfunction
Loss of contractility
dilated ventricles which fails to contract normally
low systolic ejection and cardiac output
Diastolic failure
Impaired myocardial relaxation
Ventricular wall stiffness decreased ventricular compliance impaired diastolic filling low cardiac output Systolic normal Damming back of blood in the venous system
Two phases of genesis of cardiac failure
Compensatory phase
progression to failure phase
Compensatory phase
Changes in the heart and peripheral vascular system to maintain:
CO
Arterial pressure
Peripheral perfusion
Do it by :
raised ventricular filling pressure
Myocardial structural changes
activation of neuro hormonal systems
Raised ventricular filling pressure
Increased preload -> stretching of walls -> increased contractility -> increased CO
Myocardial structural changes
Ventricular hypertrophy To increase capacity for Ventricular work and maintain cardiac performance
Activation of neuro hormonal systems
Increased Noradrenaline-> increase cardiac contraction and HR
Activation of RAAS -> sodium and water retention -> increased blood volume -> increased preload -> increased CO
Increased natriuretic peptide level when right atrial pressure high -> reduces preload, and afterload
Progression to failure
Cardiac hypertrophy leading to high demand for O2 but decreased capillary density and fibrous tissue deposition
Increased protein synthesis for formation of embryonic Fetal isoforms of contractile proteins with lower ATPase activity
Activation of fœtal proteins
Alteration in calcium handling and subendocardial ischemia impair contraction and relaxation
Reduced catecholamines
B1 receptor density reduced
Sensitivity of myocardium to b Adrenergic stimulation depressed
RAAS activation causing vasoconstriction with increased afterload and increased preload so more cardiac work
Plasma arginine vasopressin causing water retention and lead to hyponatremia
