CV IV - CHF Flashcards

1
Q

What is congestive heart failure?

A

A condition where the heart is so weak it cannot pump enough blood to meet the needs of the body

CHF is generally progressive and has a very high mortality rate

CHF results from damage to the heart, lowering its ability to contract. Reduced contractility decreases cardiac output, which triggers mechanisms to improve CO.

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2
Q

List 5 causes of CHF

A
  • Coronary artery disease
  • Hypertension
  • Cardiomyopathies
  • Arrhythmias
  • Other
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3
Q

Give the broad steps for the pathophysiology of congestive heart failure.

A

Increased preload takes a bad situation and makes it worse by signalling mechanisms to improve cardiac output.

β1 receptors signal to the brain to increase SNS activity.

  • Vasoconstriction
  • β1R in kidney: Renin angiotensin system (causing aldosterone secretion and vasoconstriction)

Elevated water and sodium retention from aldosterone leads to an every higher preload.

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4
Q

True or false? Heart failure can be left, right or bilateral.

A

True

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5
Q

What happens with left heart failure?

A

Pulmonary congestion (fluid in lungs)

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6
Q

What happens with right heart failure?

A

Systemic congestion (systemic fluid accumulation)

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7
Q

What are four general signs and symptoms of CHF?

A
  • Fatigue
  • Shortness of breath
  • Increased HR
  • Hypertrophy of surviving heart cells/tissue
  • Heart remodeling (dilation, more connective tissue, apoptosis, increase in cells with fetal characteristics) leads to high mortality!
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8
Q

What are the three main strategies in treating CHF?

A
  • Unload the heart
  • Increase strength of contraction of the heart
  • Block effects of the SNS and RAS (which increase preload)
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9
Q

Give the 4 drugs which are used to treat CHF

A
  • Diuretics
  • ACE inhibitors and angiotensin receptor blockers
  • Cardiac glycosides (eg. digoxin)
  • β blockers
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10
Q

How do ACE inhibitors and angiotensin receptor blockers treat CHF? (4)

A
  • Reduce peripheral resistance and unloads heart (decreased afterload in arteries and decreased preload in veins)
  • Decrease aldosterone secretion from adrenal glands, also unloading the heart.
  • Decreases long term remodeling of ventricles caused by CHF (reducing mortality)
  • Decrease bradykinin breakdown (hence, elevating bradykinin, a vasodilator!)
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11
Q

How do diuretics treat CHF? (4)

A

Often loop diuretics

  • Reduce preload
  • Reduce edema (fluid congestion), which unloads heart
  • Reduces hypertrophy (less fluid filled cells)

K sparing diuretics are aldosterone antagonists and decrease mortality in heart failure by decreasing fibrosis in heart

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12
Q

How do cardiac glycosides treat CHF and what are they?

A
  • Found in purple foxglove (digoxin) and used to treat ‘dropsy’
  • Increases contractility of a failing heart
  • Also used as n anti-arrhythmic drug by mimicing the effects of the PNS on the heart (slows conduction of action potentials through AV node)

Increased cardiac output does:

  • Reduces RAS activity
  • Decreases BP
  • Reduces HR
  • Decreases Na and water retention
  • Reduces preload
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13
Q

Describe the cellular mechanism of action of digoxin

A
  • Inhibiting the Na/k-pump on heart cells, effectively causing sodium to accumulate outside and calcium to come in through an exchanger (due to higher gradient), leading to stronger contraction (good for CHF)
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14
Q

List the toxic effects of digoxin

Why are these especially worrisome in elderly?

A
  • AV-node block and cardiac arrest
  • Increased calcium in cells can cause arrhythmia
  • Narrow therapeutic index

Elderly
- Digoxin eliminated by kidneys, renal function declines with age

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15
Q

How can β blockers treat CHF?

A

They decrease high SNS activity

  • β1 block: lowers HR, lowers renin, lowers contractility
  • β2 block: not useful and can cause asthma problems (bronchoconstriction)
  • α1 block: vasodilation lowers afterload
  • Reduces signs and symptoms of CHF
  • Slows CHF progression
  • Decreases mortality and reduces remodeling
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