Block 3: CHF- LV fxn, improving LVF
Terms
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- CHF Definition
- Syndrome comprising left. ventricular fxn and neuronhormonal regulation...accompanied by effort intolerance, fluid retention, and decreased longevity.
- CHF trends
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500 K new pts. in US/year
100-300K deaths/yr. - 4 Stages of treatment
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Prevention
Treatment aimed at prolonging life
Treatment aimed at reducing symptoms
End-stage considerations - Two major consequences of CHF
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decreased CO
decreased venous congestion - Decreased CO consequences
- Decreased delivery of O2 blood leading to forward failure
- Characteristics of forward failure
- Decrease exercise tolerance, increased fatigue, decreased renal perfusion, azotemia, cachexia, hypotension
- Venous congestion consequences
- More blood left behind in atrium-- Backward failure
- Characteristics of backward failure
- Increase venous pressure leads to neurohormonal response causing Na/fluid retention
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Manifestations of backward failure
6 things -
Atrial enlargement (A-fib)
Thromboembolism (venous stasis)
Pulmonary edema (lft. HF)
Peripheral edema (rt. HF)
Hypoxia/Hypoxemia
Dyspnea - What causes venous congestion in most CHF pts? Define the cause.
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Excess preload
Tension in the ventricle at end diastole - Kinds of treatment for xs preload
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Diuretics
Nitrates
Morphine
Na restriction
H2O restriction - Mainstay for xs preload treatment
- Furosemide (loop diuretic)
- What did the Rales Study find?
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27% decrease in total mortality w/addition of K+ sparing diuretics in pts. with severe HF
Also drugs that improve forward fxn indirectly help - Example of K+ sparing diuretic
- Spironolactone
- Example of drugs that improve forward fxn.
- ACEi : digoxin
- Why do you need to avoid xs diuretic use?
- Causes dehydration--inadequate preload--forward failure
- Afterload
- Wall stress during systole
- What can cause increase afterload.
- Decrease CO and the ensuing neurohormonal response.
- What drugs break the viscious cycle of increase afterload?
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ACEi
Angiotensin receptor blockers - Contractility
- Squeezing of the pump
- Definition of systolic dysfunction
- Ejection fraction <45%
- Causes of systolic dysfxn.
- MI, idiopathic dilated cardiomyopathy, HTN, ischemia, toxin (EtOH, adriamycin), infection (Chagas), viral myocarditis, tachycardia
- Drugs that directly improve systolic fxn.
- Digoxin, B-adrenergic agonists (DOPA, dobutamine, epi), phosphodiesterase inhibitors and vesnarinone
- Which drug is routinely used to treat sys dysfxn? Why?
- Digoxin, the others have increase risk of mortality
- Why should we use caution with using B-blockers early on in the treatment of systolic dysfxn?
- Reduce contractility in the short term, can make it worse.
- The result of chronic B-blocker use in sys. dysfxn.
- significant increase in ejection fraction
- What did the CIBIS II and Carvedilol trials find?
- Addition of B-1 or non-selective B-blockers to an ACEi reduces tot. mortality in HF over ACEi alone
- Should you use Ca blockers to treat sys. dysfxn.
- No they reduce contractility leading to increased mortality.
- Diastolic dysfxn.
- Abnormally increased contractility
- Who gets diastolic dysfxn
-
Left ventricular hypertrophy
HOCM
HTN* most common
**LVH and HOCM may have supranormal dP/dT - Why would pts. w/LVH or HOCM get diastolic dysfxn
- Impaired cardiac filling leads to need to increase diastolic pressure (preload) to achieve adequate CO
- How many pts w/CHF have diastolic dysfxn?
- 1/3
- What eventually happens to stroke volume in diastolic dysfxn (DD)? What is the consequence?
- Decreased SV --- decreased CO with increased EF
- Ideal therapy for DD?
- We don't know
- DD aka
- "Little old lady's heart"
- Why should we use caution when using diuretics to treat DD.
- Hypotension and low preload can result
- What is the reflex bradicardia causing syncope in cavity obliteration called?
- Bezold-Jarisch response
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Just remeber....
CO = SV * HR - :)
- Compare sys dysfxn and diastolic dysfxn with dP/dT
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Sys: ↓↓
Dias: ↑ - Compare sys vs. diastolic dysfxn for EF
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Sys: ↓↓
Dias:↑↑ - Compare sys vs. diastolic dysfxn for chamber volumes
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Sys:↑↑
Dias:↓ - Compare sys vs. diastolic dysfxn fo LV diastolic pressure
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Sys: ↑
Dias: ↑ - Name the associated use for the drug listed in sys dysfxn
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ACEi...+++ (first line Rx)
Ca blockers..CONTRAINDICATED
B-blockers..++
Diuretics..+ (spironolactone)
Digoxin..++ (symptomatic use) - Name the associated use for the drug listed in diastolic dysfxn.
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ACEi + (esp. in BP is increase)
Ca blockers ++ (verpamil)
B-blockers +++ (esp if angina)
Diuretics +/- (beware hypotension)
Digoxin CONTRAINDICATED - Treatment for acute bradycardia
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Atropine
B stimulants (dobutamine, epi) - How does chronic tachycardia decreased CO
- Limits diastolic filling and can lead to sys. dysfxn
- What is an unrecognized cause of CHF?
- A-fib w/rapid ventricular response
- What is the drug of choice for maintaining sinus rhythm in HF?
- Amiodarone
- What drug is most often used to control ventricular rate in HF pts?
- Digoxin
- Last line treatment for those w/uncontrollable tachycardia
- AV ablation
- Four factors of ventricular performance
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Preload
Afterload
Contractility
Heart rate and rhythm