Drugs to treat arrhythmia and congestive heart failure

Question 1

What are some characteristics of HF?

Answer 1

Progressive cardiac dysfunction
Raised CVP
Tiredness
Breathlessness
Oedema
Sudden cardiac death

Question 2

What are some physiological compensation methods for heart failure?

Answer 2

Heart failure = decreased CO.

Decreased CO means increased TPR to increase BP, as BP = CO x TPR. Increase TPR by increased sympathetic tone to arterioles.

Also increase activation of the renin angiotensin aldosterone system in order to raise blood pressure and filling pressures.

Question 3

How does increased RAP (right atrial pressure) lead to dilatation of the heart?

Answer 3

Increased filling pressure means increased volume in the right atrium.

Would mean that there is a increased CO due to length tension relationship in myocardium of ventricle however due to weak heart, cant pump all blood out so some is left in the ventricle.

Ventricle fills up again and puts more stress on the heart walls and they dilate further which leads to even less contraction strength and more blood in the ventricle at the end of systole.

Question 4

What are some causes of heart failure

Answer 4

Volume overload - valve regurgitation

Pressure overload - Systemic hypertension

Loss of muscle (post MI, chronic ischaemia)

Restricted filling (pericardial disease)

Chronic heart failure

Question 5

What drugs are usually used in order to improve symptoms of heart failure?

Answer 5

Diuretics
ACE inhibitors or ATI antagnists
Digoxin

Question 6

What drugs are usually used in order to improve survival of heart failure?

Answer 6

ACE inhibitor or ATI inhibitor
B blockers
Spironolactone

Question 7

Name two ACE inhibitors?

Answer 7

Captopril

Enalapril

Question 8

What is the function of ACE inhibitors?

Answer 8

Inhibit production of AIi

Inhibit aldosterone production

Vasodilation

Question 9

What are ACE inhibitors useful for?

Answer 9

Controlling K+ loss

Hypertension

Question 10

What are some side effects of ACE inhibitors?

Answer 10

hyperkaleamia

Hypotension

Cough (inhibition of bradykinin breakdown).

Question 11

What is an example of an ATII receptor blocker?

Answer 11

Losartan

Question 12

Why use ATII over ACE inhibitor?

Answer 12

No cough , better tolerated.

Question 13

What are some side effects ofATII inhibitors?

Answer 13

birth defects

Question 14

Give an example of a loop agent

Answer 14

Furosemide

Question 15

Where do loop agents act in the nephron?

Answer 15

Act at thick ascending limb of loop of henle Na/K/2CL transporter.

Question 16

What are the side effects of furosemide?

Answer 16

Hypokaleamia
Hypovolaemia
Hypomagnesia
Ototoxicity

Question 17

How much of filtered NA+ are furosemide responsible for?

Answer 17

30%

Question 18

Where do thiazides act

Answer 18

distal convoluted tubule Na/Cl transporter

Question 19

What is another effect that thiazides have?

Answer 19

Vasodilators of smooth muscle.

Question 20

What are some side effects of thiazides?

Answer 20

K loss, hypotension

Question 21

Where does Spironolactone act

Answer 21

Convoluted tubule

Question 22

What is the method of action of spironolactone

Answer 22

It is an aldosterone antagonist.

Question 23

What is spironlactone useful for

Answer 23

Controlling K+ loss

Question 24

What are some potential side effects of spironolactone?

Answer 24

hyperkalaemia.

Question 25

What are the actions of cardiotonic steroids

Answer 25

F orce increae E xcitability increase A a-v conduction decrease R rate decrease

Question 26

Name two cardiotonic steroids

Answer 26

Digitoxin, Digoxin

Question 27

What are the properties of digitoxin

Answer 27

Long duration Slow onset - half life 5-7 days High affinity for serum proteins with strong binding

Question 28

What are the properties of Digoxin

Answer 28

Rapid onset Low oral activity Low affinity for serum proteins

Question 29

What is the mechanism of action of cardiotonic steroids?

Answer 29

Cardiotonic steroids inhibit the Na/k atpase Increasing intracellular Na+ Meaning more Activity for the Na+/Ca2+ antiporter Increasing intracellular Ca2+ Increasing Ca2+ released from sarcoplasmic reticulum Increased contraction strength.

Question 30

What are side effects of cardiotonic steroids

Answer 30

Arrhythmias Gastrointestinal Narrow theraputic range. - risk of toxicity

Question 31

What is the use of digitalis?

Answer 31

To treat heart failure in old sedentary patients.

Question 32

How can nitrates be used to treat congestive heart failure?

Answer 32

GTN (glycerol trinitrate ) spray can be administered to release NO which is a vaso dilator. It therefore reduces the amount of preload and afterload

Question 33

How can GTN be administered?

Answer 33

Sublingual or injection

Question 34

When is GTN spray mostly used in heart failure?

Answer 34

Acute HF collapse due to tolerance

Question 35

What are some side effects of nitrates?

Answer 35

Headache Dizziness

Question 36

Give an example of a sympathomimetic inotrope

Answer 36

Milrinone, Dopamine (IV)

Question 37

When are sympathomimetic ionotropes usually used for HF?

Answer 37

Reversible heart failure

Question 38

What does the first class of antiarrhythmatic drugs target?

Answer 38

Na channel blockade | Reduce phase 0 slope & AP peak

Question 39

What does the second class of antiarrhythmatic drugs target?

Answer 39

B-blockers | Block sympathetic drive, reduce rate, conduction & excitability

Question 40

What does the third class of antiarrythmatic drugs target?

Answer 40

K+ channel blockers | Delay repolarisation

Question 41

What does the fourth class of antiarryhthmatic drugs target?

Answer 41

Ca 2+ blockers | Reduce rate & conduction

Question 42

Give an example of a class 1a antiarrythmatic drug?

Answer 42

Quinidine

Question 43

What is the mechanism of action of Quinidine

Answer 43

Prolong AP durating and reduce upstroke Decrease sodium entry into cell

Question 44

What is quinidine used for?

Answer 44

Ventricular arrhythmias

Question 45

What is an example of a class 1b antiarrhythmatic drug?

Answer 45

Lignocaine | Lidocaine

Question 46

What is the mechanism of action of lignocaine?

Answer 46

Decrease AP duration and reduce upstroke Prolong refractory period by binding to inactivated Na+ channels so they cant be opened again. Decrease Na+ influx

Question 47

What is lignocaine used for

Answer 47

Treatment during and immediately after myocardial infarction.

Question 48

What is an example of a class 1c anti arrythmatic drug

Answer 48

Flecainide

Question 49

What is the mechanism of action of flecainide?

Answer 49

No change in APD. Blocks sodium entry Supress Automaticity Increases refractory period

Question 50

Give an example of a class II anti arythmatic drug

Answer 50

atenolol

Question 51

How does atenolol work to treat anti arrhythmias

Answer 51

B blocker Reduces the effect of sympathetic drive Lengthens action potential duration Prolong refractory period Decrease conduction + excitability + rate

Question 52

When is atenolol used?

Answer 52

superventricular tachycardia

Question 53

Give an example of a class III anti arrhythmic drug?

Answer 53

amiodarone

Question 54

How does amiodarone work?

Answer 54

K+ channel blocker Prolong APD Prolong ERP

Question 55

What is amiodarone used to treat?

Answer 55

V tachycardia Atrial fibrillation

Question 56

Give an example of a Ca2+ channel blockers which is used to treat arrhythmias

Answer 56

Diltiazem

Question 57

How does Dilitiazem work?

Answer 57

Selectivity for cardiac muscle (verapamil & diltiazem) Block AV node ( good for supraventricular trachyarrythmia)

Question 58

What are the uses of dilitiazem?

Answer 58

Supraventricular tachycardia Reduce ventricular rate in patients with atrial fibrillation.

Question 59

Give an example of a class V anti arrythmatic drug?

Answer 59

Dixogin

Question 60

How does Digoxin work to treat arrythmias?

Answer 60

Decreases A-V conduction Decreases ventricular contraction rate.

Question 61

What is digoxin mainly used for?

Answer 61

Supraventricular tachyarrhythmias

Question 62

What drug can be used to turn atrial flutter to atrial fibrillation?

Answer 62

Digoxin - As decreases A-V conduction and rate of heart. Need to be careful to control clotting via the use of warfarin/heparin.

Question 63

What is the role of magnesium in the control of arrhythmias?

Answer 63

Decreases calcium entry into the sarcolemma, therefore less calcium released from sarcoplasmic reticulum. Regulates metabolic processes in intracellular space by binding to ATP Valuable in ventricular arrythmias in ischeamic cells especially if there is hypomegnesemia.