Block 3: clinical aspects of CHF
Terms
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- CHF is a syndrome comprising abnormal left ventricular function and neurohormomal regulation accompanied by which three things
-
effort intolerance
fluid retention
decreased longevity - what are the four stages of treatment of CHF
-
1. prevention of heart failure
2. treatment to prolong life
3. treatment to reduce sx
4. end-stage considerations - what are the two major consequences of LV dysfunction
-
decreased CO
venous congestion - the decreased CO resulting in reduced delivery of oxygenated blood to the vital organs and skeletal muscle is often called...
- forward failure
- what are the manifestations of forward failure
-
DEC EXERCISE TOLERANCE
inc fatigue
dec renal perfusion w/ azotemia
cachexia
hypotension - less blood being pumped out of the ventricle resulting in more left behind in the atrium, resulting in increased venous pressure and congestion is called...
- backward failure
- what else contributes to backward failure
- compensatory neurohumoral response- it causes Na/fluid retention
- what are manifestations of backward failure
-
atrial enlargement (-> cause a-fib)
thromboembolism (venous stasis)
edema
dyspnea
hypoxemia
hypoxia - what four independent factors determine left ventricular performance
-
preload
afterload
contractility
heart rate and rhythm - what is preload
- the tension in the ventricle at end diastole
- what does excess preload cause
- venous congestion- diuretics, nitrates, morphine, Na restriction, water restriction are all effective
- What is the traditional mainstay of therapy for those with intractable fluid overload and was shown by the RALES trial to also reduce mortality
-
loop diuretics like furosemide are traditional
potassium sparing diuretics like spironolactone are also good - what type of drug can reduce excess preload indirectly by improving forward flow through the ventricle
-
ACEI
or
DIGOXIN - what can excessive diuretic use cause
- dehydration -> inadequate preload and forward failure
- what is afterload
- the wall stress during systole, largely determined by systolic blood pressure
- what is the vicious cycle of afterload?
- severe hypertension -> chronic excess afterload -> reduced CO -> compensatory neurohumoral response -> increased afterload -> worsened systolic heart function -> reduced CO ...
- what can break the vicious afterload cycle by reducing the neurohumoral response and lowering afterload, causing improved cardiac function and less venous congestion
- ACEI
- what is contractility
- the squeezing strength of the pump
- what is systolic dysfunction
- ejection fraction <45%
- What are the most common causes of reduced contractility
- MI and idiopathic dilated cardiomyopathy
- Name four classes/drugs that directly improve systolic function
-
DIGOXIN
beta agonists (DA, dobutamine)
phophodiseterase inhibitors
vesnarinone - Why is digoxin the only drug used to directly improve systolic function
- the others INC mortality in clinical trials despite improving symptoms
- What is the short term and long term effect of beta blockers on contractility
-
short term reduction
chronic response is INCREASED ejection fraction - What do calcium channel blockers do to contractility
- (except amlodipine) they reduce contractility, leading to increased mortality in patients with systolic dysfunction
- can abnormally increased contractility cause heart failure
- yes- concentric LV hypertrophy; hypertrophic cardiomyopathy
- how many CHF patients have a defect in diastolic function
- 1/3
- what is diastolic dysfunction often called
- little old lady's heart
- What is frequently presribed for diastolic dysfunction
- negative inotropes like beta blockers and verapamil
- what is the term when excessive afterload reduction causes a situation where the ventricle completely empties at end-systole -> precipitating syncope due to reflex bradycardia (Bezold-Jarisch response) or pulmonary edema due to extreme tachycardia
- cavity obliteration
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Systolic dysfuction:
dPdT
Ejection fraction
chamber volumes
LV diastolic pressure
etiologies -
dPdT- dec dec
Ejection fraction- dec dec
chamber volumes- inc inc
Lv diastolic pressure- inc
etiologies- ischemia, hypertension, idoipathic, toxin (EtOH), infection (chagas) -
diastolic dysfunction:
dPdT
Ejection fraction
chamber volumes
LV diastolic pressure
etiologies -
dPdT- inc
ejection fraction- inc inc
chamber volumes- dec
LV diastolic pressure- inc
etiologies- hypertension, HOCM -
Systolic dysfunction:
ACE inhibitors
CCB
beta blockers
diuretics
digoxin -
ACE inhibitors- YES- 1ST LINE
CCB- CONTRAINDICATED (except amlodipine)
beta blockers- ok
diuretics- spironolactone
DIGOXIN- yep -
diastolic dysfunction:
ACE inhibitors
CCB
beta blockers
diuretics
digoxin -
ACEI- if BP elevated
CCB- verapamil
beta blockers- YES,esp w/ angina
diuretics- beware hypotension
digoxin- CONTRAINDICATED - What do you do for chronic symptomatic bradycardia
- pacemaker- there is no drug therapy
- What do you do for acute bradycardia
-
atropine if excess vagal tone is the problem
or
beta agonist- dobutamine, epi - chronic tachycardia reduces cardiac output by limiting __ filling and can eventually cause severe __ dysfunction
-
diastolic
systolic - what is an underecognizaed cause of CHF
- a-fib
- what is the drug of choice for maintaining sinus rhythm in heart failure
- amiodarone
- what can control ventricular rate in a-fib
- digoxin
- what do you do for patietns with tachycardia that can't be controlled with drugs
- surgical ablation of the AV node