CHF in Children (Sison) Flashcards
Compensatory mechanisms for congestive heart failure
- increase preload
- increase cardiac rate
- increase afterload
- myocardial hypertrophy and/or LV remodeling
Discuss increase preload as one of the compensatory mechanisms for congestive heart failure
Increase in venous return stretches cardiac muscle cells –> better contractility & larger SV
Salt and water retention (via aldosterone and AVP upon actiation of JG cells in kidney to produce renin)
Sympathetic stimulation (via B1 receptors)
Discuss increase cardiac rate as one of the compensatory mechanisms for congestive heart failure
Increase cardiac output –> increase tissue perfusion
Sympathetic stimulation - increase inotropy (contractility), heart rate (chronotropy), conduction velocity (dromotropy)
B1 - tachycardia, arrhythmia, salt and water retention (via JG cells)
Discuss increase afterload as one of the compensatory mechanisms for congestive heart failure
Increase peripheral vascular resistance
Sympathetic stimulation
a1 receptor activation = peripheral vasoconstriction (increases BOTH afterload and preload; constriction of veins, reduced compliance, reduced blood pooling, improved venous return)
angiotensin II
AVP/ADH
Discuss myocardial hypertrophy and/or LV remodeling as one of the compensatory mechanisms for congestive heart failure
Initially: results in a larger capacity to do work
Long term: associated with apoptosis, fibrosis, reduced overall contractility
Increased levels of ….. lead to increased hypertrophy
-catecholamines, angio II, aldosterone
Increased levels of ….. lead to increased hypertrophy
catecholamines, angio II, aldosterone
When do the clinical manifestations of heart failure arise?
Adaptive compensatory mechanisms cause degeneration of myocardium –> cannot meet increased cardiac demands
What are the direct effects of cardiac disease in terms of PBF, LVEDP, and systemically?
increased pulmonary blood flow –> arterial congestion
increased LVEDP and left arterial pressure (LAP) –> pulmonary venous congestion
systemic congestion –> hepatomegaly, neck distension, edema
What are the effects of maladaptive compensatory mechanisms in congestive heart failure?
effects in increased preload, afterload, sympathetic stimulation
What are the effects of increased preload as one of the compensatory mechanisms in congestive heart failure?
Preload: amount of blood that will stretch LV in preparation for contraction
too much preload –> heart dilation –> decreased efficiency
pulmonary congestion - tachypnea, dyspnea, orthopnea (lying down, more venous return to heart by gravity, more drowning effect)
systemic congestion - hepatomegaly (chronic passive congestion), bipedal edema
pallor - due to hemodilution and vasoconstriction from increased salt and water retention
What are the effects of increased sympathetic stimulation as one of the compensatory mechanisms in congestive heart failure?
tachycardia
diaphoresis (excessive sweating)
arrhythmia (B1 agonists usual side effect)
What are the effects of increased afterload as one of the compensatory mechanisms in congestive heart failure?
vasoconstriction
cold extremities
pallor
(usually involve extremities - peripheral)
What are the hallmarks of heart failure?
decreased oxygen delivery
easy fatigability –> shock –> death
Manifestations of easy fatigability as one of the hallmarks of heart failure
intermittency in feeding
gets tired easily
Manifestations of shock as one of the hallmarks of heart failure
blood supply not enough to support basic activities of the body
- altered sensorium (irritability, low brain oxygen supply)
- decreased urine output (blood flow from kidneys moved towards priority organs: brain, heart, adrenal glands)
- tachycardia
- cold extremities
- hypotension
