Congestive Heart Failure - Howlett 3

Question 1

CHF

Answer 1

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

Question 2

Causes of CHF

Answer 2

Coronary artery disease
Hypertension
Cardiomyopathies
Arrhythmias

Question 3

Pathology of CHF

Answer 3

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

Question 4

Left heart failure

Answer 4

Pulmonary congestion and fluid build up

Question 5

Right heart failure

Answer 5

Systemic congestion and systemic fluid build up

Question 6

Symptoms of CHF

Answer 6

Fatigue
Shortness of breath 
Increase HR
Hypertrophy
Remodelling

Question 7

Strategies in treating CHF

Answer 7

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

Question 8

Drugs used to treat CHF

Answer 8

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

Question 9

Diuretics

Answer 9

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

Question 10

Loop diuretics

Answer 10

Loop of hence
Very powerful
Chance secretion of K into urine

Question 11

Aldosterone receptor antagonists

Answer 11

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

Question 12

Drugs that inhibit the RAS

Answer 12

ACE inhibitors, A2 receptor blockers, renin inhibitors

Reduce total peripheral resistance, decrease aldosterone secretion, decreases long term remodelling of ventricles

Question 13

ACE inhibitors

Answer 13

Decrease bradykinin breakdown

Question 14

Bradykinin

Answer 14

Vasodilator peptide that is broken down by ACE

Question 15

Cardiac glycosides

Answer 15

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

Question 16

Digoxin

Answer 16

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

Question 17

Toxic effects of digoxin

Answer 17

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

Question 18

Beta-blockers

Answer 18

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