Congestive Heart Failure - Howlett 3 Flashcards Preview

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Flashcards in Congestive Heart Failure - Howlett 3 Deck (18)
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1

CHF

Heart is so weak it cannot pump enough blood to meet the needs of the body
Progressive
Very high mortality rate
Decrease CO, which triggers mechanisms to improve CO, which worsens the situation
Treatment is to dampen down reflex actions trying to compensate

2

Causes of CHF

Coronary artery disease
Hypertension
Cardiomyopathies
Arrhythmias

3

Pathology of CHF

Increased Na and water retention by increasing aldosterone to increase preload
Increased vasoconstriction to increase afterload
This further reduces CO as heart damage cannot keep up

4

Left heart failure

Pulmonary congestion and fluid build up

5

Right heart failure

Systemic congestion and systemic fluid build up

6

Symptoms of CHF

Fatigue
Shortness of breath
Increase HR
Hypertrophy
Remodelling

7

Strategies in treating CHF

Unload the heart
Increase the strength of contraction of the heart
Block the effect of the SNS and RAS (compensatory responses)

8

Drugs used to treat CHF

1. Diuretics
2. Drugs that inhibit RAS
3. Cardiac glycosides
4. Beta blockers

9

Diuretics

Decrease salt and water retention
Decrease preload (decrease circulating volume)
Decrease afterload
Decrease edema
1. Loop diuretics
2. Aldosterone receptor antagonists

10

Loop diuretics

Loop of hence
Very powerful
Chance secretion of K into urine

11

Aldosterone receptor antagonists

K-sparing diuretics
Mild diuresis
Increased heart function
Aldosterone contributes to fibrosis

12

Drugs that inhibit the RAS

ACE inhibitors, A2 receptor blockers, renin inhibitors
Reduce total peripheral resistance, decrease aldosterone secretion, decreases long term remodelling of ventricles

13

ACE inhibitors

Decrease bradykinin breakdown

14

Bradykinin

Vasodilator peptide that is broken down by ACE

15

Cardiac glycosides

Found in purple foxglove
Modernly introduced to treat dropsy
Digoxin clinically
Increases contractility

16

Digoxin

Clinically used cardiac glycoside
Increases contractility of heart
Anti-arrhythmic drug
Mimics effects of PNS on heart
Slows conduction of AP throughout AV node
Inhibits Na/K ATPase
Less Ca removed due to decreased Na gradient (Na/Ca exchanger) which increases contraction
CO goes up which reduces compensatory actions in SNS

17

Toxic effects of digoxin

1. AV node: can cause AV blockage and cardiac arrest by stopping impulses from travelling from atria to ventricles
2. Ventricles: narrow therapeutic index, increases Ca which may trigger arrhythmia
Can be particularly bad in elderly as their kidneys are slower

18

Beta-blockers

Decrease SNS activity
Metoprolol, carvedilol
Highly secretive
B1: decrease HR, renin
B2: not useful, in airway
A1L decreases afterload
Reduces signs and symptoms of CHF
Slows progression of CHF
Decreases mortality
Reduces remodelling