Heart Failure Flashcards
heart failure (HF)
inability of heart to pump sufficiently
HF may result from what?
loss of ability to contract
impairment to outflow
excess work demands
what does HF result to?
↓output (forward effect)
congestion (backup effect)
what does ↑workload of ventricles result to?
hypertrophy and eventually failure
which ventricles does HF involve?
initially involve left or right ventricle
once one ventricle fails, other will eventually fail as well
HF can result from two kinds of dysfunction or both
systolic & diastolic dysfunction
systolic dysfunction
heart fails to generate enough force to adequately pump blood => ↓contractiliy and stroke volume
diastolic dysfunction
reduced ability of ventricle to fill d/t failure of myocardium to relax or ↑stiffness of ventricle or valvular stenosis
what effect does systolic dysfunction lead to
“foward” manifestations of HF - ie. ↓CO
what effect does diastolic dysfunction lead to
“backup” effects of HF - ie. congestion
HF etiology, all of which lead to ↓CO
- MI
- tricuspid, aortic valve incompetence
- pulmonary, mitral, aortic valve stenosis
- respiratory disease
- pericardial disease
- hypertension
- hyperthyroidism
- myocarditis
result of respiratory disease in HF
↑pulmonary resistance - damage of lung capillaries => ↑workload for right ventricle
result of MI in HF
↓muscle/contractile mass
result of tricuspid valve incompetence in HF
↓left ventricle preload
result of pulmonary valve stenosis in HF
↓left ventricle preload
↑right ventricle afterload
result of mitral valve stenosis in HF
↓left ventricle preload
↑right ventricle afterload
result of aortic valve stenosis in HF
↑left ventricle afterload
result of aortic valve incompetence in HF
volume overload
result of hypertension in HF
↑afterload
↑left ventricle workload
result of hyperthyroidism in HF
↑metabolic rate
↑SNS => ↑BP, tachycardia, HF
result of pericardial disease in HF
restricts filling of heart
result of myocarditis in HF
bacterial or viral infection => loss of contractility
congestive heart failure (CHF)
HF accompanied by congestion of body tissues w/ blood
impaired heart function symptoms
initially asymptomatic - period of compensatory mechanisms (compensated HF)
eventually measures fail and/or aggravate failure => decompensated failure w/ symptoms
CHF compensations
- frank-starling mechanism
- ↑SNS
- renin-angiotensin mechanism
- ↑endothelin
- myocardial hypertrophy
frank-starling mechanism compensation of CHF
↑preload (ventricular end-diastolic volume) => ↑stretch, contraction force
however,
over-stretching => ↓contraction force, ischemia - ↑O2 demand => impaired function
↑SNS compensation of CHF
baroreceptor reflex => ↑HR, ↑total peripheral resistance, ↑contractility
however,
↑HR => ↓ventricular filling, arrhythmias and ↑total peripheral resistance => ↑afterload
renin-angiotensin mechanism compensation of CHF
activated by ↓blood flow to kidneys
however,
↑total peripheral resistance => ↑afterload and angiotensin contributes to hypertrophy
↑endothelin compensation of CHF
released from blood vessel endothelial cells
strong vasoconstrictor
however,
↑total peripheral resistance => ↑afterload and endothelin contributes to hypertrophy
myocardial hypertrophy compensation of CHF
response to ↑workload
↑number of contractile elements
however,
↑O2 demand => ischemia, fibrosis, impaired function
remodeling of ventricle => ↓chamber size
left-sided CHF etiology
- volume overload
- pressure overload
- loss of muscle mass
- loss of contractility
- restricted filling
volume overload in left-sided CHF occurs
occurs w/ regurgitant mitral or aortic valves and high output states such as anemia or hyperthyroidism
pressure overload in left-sided CHF occurs
occurs w/ hypertension and aortic stenosis
loss of muscle mass in left-sided CHF examples
examples:
left ventricular MI
inflammatory disease like lupus
loss of contractility in left-sided CHF occurs
can occur as a result of bacterial or viral infection (ie. myocarditis) or from certain poisons and toxins
examples of restricted filling in left-sided CHF
example:
mitral stenosis
pericardial disease
left-sided CHF manifestations
- forward effect: ↓CO
- backup effect: pulmonary congestion
how is forward effect manifested in left-sided CHF
fatigue, weakness, dyspnea, exercise & cold intolerance, cyanosis
compensatory manifestations of forward effect in left-sided CHF
tachycardia, pallor, daytime oliguria, nocturia, polycythemia
uncompensated manifestations of forward effect in left-sided CHF
cyanosis, anorexia, cachexia
what does backup effect lead to in left-sided CHF
↑capillary pressure and edema - fluid forced into alveoli
interferes w/ gas exchange => hypoxemia and predisposes to pneumonia
how is backup effect manifested in left-sided CHF
orthopnea, cough, dyspnea, hemorrhage in lungs (blood in sputum)
right-sided CHF
often follows left-sided CHF as pulmonary congestion impairs flow into lungs from right ventricle
right-sided CHF causes
- left ventricular failure
- loss of muscle mass
- cor pulmonale
- tricuspid valve incompetence
- pulmonary valve stenosis
- congenital defects
left ventricular failure in right-sided CHF
pulmonary edema increases afterload on right ventricle
ie. hypoxic vasoconstriction
loss of muscle mass in right-sided CHF
right ventricular or inferior MI
cor pulmonale in right-sided CHF
right ventricle failure occuring secondary to pulmonary disease
impaired ventilation in cor pulmonale
=> pulmonary vasoconstriction that increased afterload and often results in failure
what can cause cor pulmonale
pulmonary embolism
congenital defects in right-sided CHF
pulmonary obtructions or shunts can increased workload on right ventricle causing it eventually fail
right-sided CHF manifestations
- forward effect: ↓CO
- backup effect: congestion in systemic circulation => peripheral edema
forward effect in right-sided CHF
same as left-sided CHF
manifestation in backup effect in right-sided CHF
- generalized edema, ascites or dependant edema
- hepatomegaly and splenomegaly
- ↑jugular venous pressure
ascites
collection of fluid in peritoneal space
dependent edema
swelling of feet and legs
hepatomegaly and splenomegaly in right-sided CHF
fluid accumulation in liver or spleen => distention and upper quadrant pain
↑jugular venous pressure in right-sided CHF
congestion into cranium can create CNS symptoms: headache, visual disturbance and flushed face
most common cause of CHF in children
congenital heart defects
s/s of CHF in children
same as adults:
- tachycardia
- fatigue
- effort intolerance
- irritability
- cough
- anorexia
- abdominal pain
- oliguria
- hepatomegaly
differences of CHF in children and adult
- dependent edema and ascites are rare
- jugular distention is hard to detect
- excessive sweating
why is jugular distenstion hard to detect in children w/ CHF
children have short, chubby necks
most common difference of CHF in children
interstitial edema in lungs is more common than alveolar pulmonary edema -> impairs ability of lungs to expand (ie. ↓compliance) and ↑work of breathing
what does interstitial edema lead to in CHF in children
tachypnea
↑respiratory effort
two kinds of drug therapies for HF
drugs that reduce mortality
drugs that reduce symptoms
how do drugs that reduce mortality work for treating HF?
↓workload of heart
drugs that reduce mortality
- ACE inhibitors
- beta blockers
- aldosterone antagonists
- coronary vasodilators
ACE inhibitors in HF treatment
ex: Altase, Coversil
↓angiotensin activation blocks systemic vasoconstriction effect
beta blockers in HF treatment
block beta adrenergic receptors => ↓epinephrine effect
beta-1 blockers can ↓renin release and ↓cardiac muscle contraction
aldosterone antagonists in HF treatment
block effects of aldosterone => ↓absoprtion of Na+ and water => ↓BV => ↓BP
coronary vasodilators in HF treatment
ex. nitroglycerine
cause coronary arteries to dilate and ↑blood flow to myocardium
drugs that reduce symptoms
- digitalis
- vasodilators
- diuretics
digitalis in HF treatment
alkaloid derived from foxglove
↑vagal tone => ↑contractility => ↓HR => ↓workload
vasodilators in HF treatment
ex. ACE inhibitors, nitrates, CCBs, alpha-1 blockers
cause ↓systemic vasodilation => ↓afterload
diuretics in HF treatment
ex. lasix
↑urine output => prevent fluid overload
BV does not increase => ↓risk of edema, dyspnea
