Drugs used in management of heart failure and cardiac arrhythmias

Question 1

Mechanism of action of inotropes?

Answer 1

Increase force of contraction of heart

Question 2

Mechanism of action of diuretics?

Answer 2

Increase in passage of urine - excrete Na and water

Question 3

Mechanism of action of beta blockers?

Answer 3

Stabilise heart rhythm by inhibiting action of adrenaline

Question 4

Effect of ACE inhibitors and angiotensin receptor blockers?

Answer 4

Dilation of BV and reduce work of contraction of the heart

Question 5

Name 2 types of inotropes and its effect?

Answer 5

Adrenoreceptor agonist
Mimic effects of adrenaline
+ve inotropic effects = increase contractility of heart

Cardiac glycosides
antiarrythmic and inotrpic effects

Question 6

Why do adrenoreceptor agonists (inotropes) have to be given by continuous iv drip?

Answer 6

Very short half life (30 secs)

Question 7

Consequences of adrenoreceptor agonists?

Answer 7

Arrythmias and increase myocardial oxygen demand

Question 8

Action of cardiac glycosides?

Answer 8

Antiarrythmic = vagolytic effects = reduce rate and conduction in sinus and AV node
Inotropic = increase intracellular Ca+

Question 9

Indications for cardiac glycosides

Answer 9

Supraventricular arrythmias
Chronic atrial fibrillation
Heart failure (improve symptoms)

Question 10

Describe pharmacology of cardiac glycosides?

a) elimination
b) effect of this on certain patients
c) therapeutic index
d) when plasma concentrations should be monitored?

Answer 10

a) hepatic
b) impaired renal function = lower doses
c) narrow TI = easily toxic
d) monitor when possible toxic symptoms showing or lack of efficacy of drug

Question 11

How do cardiac glycosides cause inotropic effects?

Answer 11

Inhibti Na K pump - so Sodium accumulates in the cell
This prevents Na Ca exchanger which normally pumps Na in and Ca out
So Ca accumulates int he cell = inotropic

Question 12

Possible effect of increased Na in the cell due to to cardiac glycoside treatment?

Answer 12

Arrhythmias

Question 13

Adverse effects of cardiac glycosides?

Answer 13

Cardiac = heart block, supra-ventricular and ventricular arrhythmias
Non-cardiac = nausea, vomiting, constipation, confusion, visual disturbances

Question 14

How can diuretics be catergarised?

Answer 14

Causing potassium loss (K+ loosing)

Causing potassium retention (K+ sparing)

Question 15

Effect of K+ loosing and K+ sparing diuretics?

Answer 15

K+ lost with water

K= retention despite loss of water

Question 16

Adverse effects of loop diuretics result from …

Answer 16

Profound diuresis

Question 17

Why do loop diuretics cause profound diuresis?

Answer 17

Stronger diuretics

Question 18

What kind of adverse effects are caused by thiazide diuretics?

Answer 18

Metabolic effects e.g. impaired glucose intolerance

Question 19

Generally what are common adverse effects of K+ loosing diuretics like loop and thiazide diuretics?

Answer 19

Hypokalaemia
Gout
Pancreatits

Question 20

How do K+ sparing diuretics like spirolactone work?

Answer 20

Inhibit aldosterone

Question 21

Adverse effects of spironolactone (K+ sparing diuretic)

Answer 21

Gynaecomastia
Hyperkalaemia
GI disturbances

Question 22

Effect of ACE inhbitors?

Answer 22

Vasodilation, reduce aldosterone secretion, decrease Bp, reduced sympathetic NS activity

Question 23

Adverse effects of ACE inhbitors?

Answer 23

Renal failure
Cough
Hyperkalamia
Angioedema

Question 24

Effects of angiotensin receptor blockers?

Answer 24

Vasodilation, redcued SNS activity

Question 25

Benefits of angiotensin receptor blockers vs ace inhibitor?

Answer 25

No cough

Question 26

Describe cardiac action potential?

Answer 26

Fast sodium entry inactivation of sodium channels Slow calcium influx Efflux of K+ = repolarisation Spontaneous diastolic drift towards threshold potential

Question 27

What is atropine?

Answer 27

Antimuscarinic anticholinergic drug | Blocks vagal inhibition of sinus and AV node

Question 28

adverse effects of atropine?

Answer 28

Dry mouth Postural hypotension Anticholingeric

Question 29

What is heart block?

Answer 29

Bradycardia due to impulses not being conducted through AV node or to ventricles

Question 30

What is atropine used for?

Answer 30

Treat heart block

Question 31

Adverse effects of atropine and reason for these?

Answer 31

Dry mouth Postural hypotension Due to it being an anticholinergic drug

Question 32

Name another drug aside from atropine that can be used to treat bradycardia arrythymias?

Answer 32

Isoproterenol

Question 33

Describe isoproterenol mechanism of action?

Answer 33

B1 and B2 adrenoreceptor agonist = positive chronotropic effect on the sinus node = increase heart rate

Question 34

Adverse effects of isoproterenol?

Answer 34

tachycardia and arrythmias due to it being sympathomimetic

Question 35

Name the 2 categories of tachyarrhthymias?

Answer 35

Supraventricular tachycardia - somewhere above the bundle of His (sinus node, atria) Ventricular tachycardia = bundle of His or ventricular tissue

Question 36

What type of tachyarrhythmias are more serious?

Answer 36

Ventricualr tachycardias are more life threatening than supraventricular tachycardia

Question 37

``` What is the mechanism of action of these antiarrhythmic drugs: class I Class II Class III Class IV ```

Answer 37

Class I = inhibit phase 0 depolarisation = block fast entry of Na = sodium channel blockers Class II = antisympathetic drugs (beta blockers) = inhibit phase 4 diastolic drift = slow HR Class III = potassium channel blockers = inhibit phase III depolarisation = prolong refractory period Class IV = inhibit Ca-dependent depolarisation = calcium channel blockers = block AV node

Question 38

Generally how do anti-arrhythmic drugs prevent arrhythmias?

Answer 38

Altering conduction velocity - interfering with re-entry Reduce intrinsic pace maker rate Prolong effective refractory period

Question 39

What are the general adverse effects of antiarrhythmic drugs?

Answer 39

Can precipitate arrhythmias | Negative inotropic effects = hypotension and heart failure

Question 40

Lidocaine is a class I drug. Describe its action

Answer 40

Blocks fast sodium channels and slows phase 0 depolarisation = shortens action potential duration

Question 41

When is lidocaine prescribed for arrhythmias?

Answer 41

Ventricular arrhythmias

Question 42

Adverse effects of lidocaine as an antiarrhythmic drug?

Answer 42

Hypotension, heart block, neurotoxicity = fits

Question 43

Amiodarone is a class III antiarrhythmic drug, describe its action.

Answer 43

Prolongs action potential duration and refractory period = lengthened QT interval

Question 44

Indications of class III drugs?

Answer 44

Ventricular and supra-ventricular arrhythmias

Question 45

Amiodarone (class III) adverse effects?

Answer 45

``` Thyroid disturbances Pulmonary fibrosis Pro-arrhythmia Hepatitis Blue/grey skin discolouration ```

Question 46

Verapamil is a class IV drug. Describe its action?

Answer 46

Calcium channel blocker - reduces rate and conduction in sinus and AV node

Question 47

Indications for class IV drugs?

Answer 47

Supraventricular arrhythmias

Question 48

Adverse effects of class IV drugs?

Answer 48

Heart failure, hypotension, constipation, vasodilation, oedema