Cardiology

Question 1

Adenosine MOA

Answer 1

Block angiotensin converting enzyme (ACE) preventing conversion of angiotensin I to angiotensin II.

Transient heart block in the AV node

Agonist of the A1 receptor in AVN → inhibiting adenylyl cyclase → reduced cAMP → hyperpolarisation by increasing potassium efflux

Short t ½ of 8-10 seconds.

Question 2

Uses of adenosine

Answer 2

Terminate SVT

Question 3

S/E Adenosine

Answer 3

Chest pain - typically transient and resolves without intervention.

Bronchospasm

Transient flushing / warmth

Enhance conduction down accessory pathways resulting in WPW syndrome and inc ventricular rate.

Question 4

C/I Adenosine

Answer 4

Enhanced by dipyridamole (antiplatelet agent)

Blocked by theophyllines

Asthmatics - can cause bronchospasm.

Question 5

Amiodarone MOA

Answer 5

a class III antiarrhythmic agent

Blocking potassium channels inhibiting repolarisation and prolonging action potential.

T ½ is 20-100 days - hence higher loading dose.

Question 6

Use of amiodarone

Answer 6

Atrial Tachycardia
Nodal Tachycardia
Ventricular Tachycardia

Question 7

S/E Amiodarone

Answer 7

Central veins only as it will cause thrombophlebitis.
Prolongation of QT interval
Bradycardia

Other:
Thyroid dysfunction
Corneal deposits and photosensitivity
Pulmonary fibrosis or liver fibrosis
Slate grey appearance

Question 8

C/I Amiodarone

Answer 8

Decreases metabolism of warfarin
Interacts with drugs used p450 inhibitors.

Question 9

Monitoring Amiodarone

Answer 9

TFT, LFT, U+E + Cxr prior to treatment
TFT, LFT every 6 months.