Block 13- Week 3

Question 1

Verapamil

Answer 1

Class IV anti arrhythmic agent
Inhibits voltage dependent L type Ca channels causing a reduction in Inotropy and chronotropy reducing HR and BP
Only given via IV

Dilitazem more commonly used but not IV given

Question 2

Dilitazem

Answer 2

Calcium channel inhibitor

Used alone or with an ACE inhibitor

Treat hypertension , chronic stable angina pectoris prinzmetals variant angina

Question 3

Atenolol

Answer 3

B-1 selective antagonist

Bisoprolol used more often now

Competes with catecholamines for binding at the receptor in heart and vascular smooth muscle resulting in a reduction in HR , CO , BP

Question 4

Atropine

Answer 4

Antimuscurinic agent

Inhibits M2 receptor

Stops bradycardia or asystole

Also used in partial heart block when bagel activity is an aerological factor

Question 5

Glyceryl trinitrate (GTN)

Answer 5

Vasodilator

Treats angina pectoris and peri operative HTN

Converted to NO which activates guanylate Cyclase stimulating cGMP which activates protein kinase G leading to dephosphorylation of myosin light chain of smooth muscle fibres and decr Ca leading to relaxation of smooth muscle cells and vasodilation

Question 6

Amiodarone

Answer 6

Antianginal and anti arrhythmic agent

Class III anti arrhythmic agent

Blocks K channels and non comp a and B adrenergic inhibitor

Question 7

Adenosine

Answer 7

Endogenous nucleoside

Distinguish between VT and SVT - it helps in SVT but not in VT

Activated A1 and A2 adenosine receptors and slows ca influx hence relaxes smooth muscle

Slow conduction time thru AV node so interrupt re entry pathways thru AVN restoring normal sinus rhythm in Pts with SVT .

Question 8

Lidocaine

Answer 8

Anaesthetic agent

Class Ib drug

Blocks voltage sensitive Na channels during phase 0 of cardiac AP slowing and depressing impulse conduction

Used to treat VT associated with MI , depresses V excitability and incr stimulation threshold of V during diastole , SAN unaffected