Drugs modifying cardiac rate and force

Question 1

Blocker of HCN channels?

Answer 1

Ivabradine

Question 2

Vagal tone on the heart

Answer 2

Vagal tone slows the intrinsic heart rate from ~100bpm to ~70bpm

Question 3

Nerve supply to the SA and AV node

Answer 3

vagus nerve

Question 4

Nerve supply to SA node, AV node and myocardium

Answer 4

Sympathetic

Question 5

Lead I

Answer 5

RA to LA

Question 6

Lead 2

Answer 6

RA - LL

Question 7

Lead 3

Answer 7

LA - LL

Question 8

P

Answer 8

Atrial depolarisation

Question 9

QRS

Answer 9

Ventricular depolarisation

Question 10

T

Answer 10

Ventricular repolarisation

Question 11

PR interval

Answer 11

AV node delay

Question 12

ST segment

Answer 12

Ventricular systole

Question 13

TP interval

Answer 13

diastole

Question 14

Dobutamine, selective?

Answer 14

Yes, beta 1 adrenoceptors

Question 15

Metoprolol
Atenolol
Propanolol
Which are selective?

Answer 15

Metoprolol + atenolol are beta-1 antagonists

Propanolol is non selective

Question 16

Adverse effects of beta blockers?

Answer 16

Bronchospasm
Aggravation of cardiac failure
Bradycardia
Hypoglycemia
Fatigue
Cold extremities

Question 17

Clinical uses of atropine (increases heart rate)

Answer 17

To reverse bradycardia following myocardial infarction (in which vagal tone is elevated)
As an adjunct to anaesthesia
In anticholinesterase poisoning (to reduce excessive parasympathetic activity)

Question 18

Which transporter does digoxin block?

Answer 18

Blocks the NA+/K+ATPase

Question 19

Binds to troponin C in cardiac muscle sensitising it to the action of Ca2+

Answer 19

Levosimendan (calcium sensitiser)