Arrhythmias

Question 1

Describe the negative inotropic effects of anti-arrhythmic drugs. What extra care is needed due to this feature?

Answer 1

They tend to be additive. Care is needed when using two or more, especially if myocardial function is impaired.

Question 2

Define inotrope.

Answer 2

An agent which alters the force or energy of muscle contractions.

Question 3

Describe the difference between positive and negative inotropes.

Answer 3

Positive inotropes increase the strength of muscular contractions whilst negative inotropes decrease the force of muscular contractions.

Question 4

Which electrolyte imbalance can affect the pro-arrhythmic nature of many drugs?

Answer 4

Hypokalaemia.

Question 5

What treatment should be used for life-threatening, new-onset atrial fibrillation?

Answer 5

Emergency electrical cardioversion.

Question 6

Define electrical cardioversion.

Answer 6

The use of electricity to return the heart to a regular rhythm.

Question 7

If new-onset atrial fibrillation is not life-threatening, what should be used to return the heart rhythm to normal?

Answer 7

Pharmacological or electrical cardioversion.

Question 8

What can be used as monotherapy to control ventricular rate?

Answer 8

A standard beta-blocker or a rate limiting calcium-channel blocker (e.g. diltiazem or verapamil).

Question 9

Which beta-blocker should not be used for the control of ventricular rate?

Answer 9

Sotalol.

Question 10

If monotherapy for ventricular rate control does not achieve the desired result, what can be used as dual therapy?

Answer 10

A beta-blocker, digoxin or diltiazem.

Question 11

Define sinus rhythm.

Answer 11

Cardiac rhythm with depolarisation beginning at the sinoatrial node.

Question 12

How can sinus rhythm be maintained post-cardioversion?

Answer 12

With a standard beta-blocker.

Question 13

If a standard beta-blocker can’t be use to maintain sinus rhythm after cardioversion, what alternatives can be used?

Answer 13

Sotalol, flecainide, propafenone or amiodarone.

Question 14

Verapamil should be avoided in patient’s on beta-blockers. Why?

Answer 14

Increased risk of severe hypertension and asystole.

Question 15

What length of time should atrial fibrillation be present for before electrical cardioversion is preferred?

Answer 15

48 hours +.

Question 16

How long should a patient be fully anticoagulated for before and after electrical cardioversion?

Answer 16

At least 3 weeks before and 4 weeks after.

Question 17

What should all patients with atrial fibrillation be assessed for?

Answer 17

Their stroke risk and their need for thromboprophylaxis.

Question 18

What does an AF patient’s risk of stroke and need for thromboprophylaxis need balancing with?

Answer 18

Their bleeding risks.

Question 19

What score is used to determine the stroke risk of a patient with AF?

Answer 19

CHADSVASC.

Question 20

What score is used to determine a patient’s risk of bleeding?

Answer 20

HASBLED.

Question 21

What are the risk factors used to determine a patient’s CHADSVASC score?

Answer 21

Congestive heart failure, hypertension, age greater than 75 years, age between 65-74, diabetes mellitus, vascular disease, stroke/TIA/thromboembolism, gender (female).

Question 22

What are the risk factors used to determine a patient’s HASBLED score?

Answer 22

Hypertension, abnormal liver function, abnormal renal function, alcohol intake over 8u/wk, history of stroke, history of haemorrhage, labile INRs, age over 65 years, drug use (antiplatelets or NSAIDs).

Question 23

What CHADSVASC score constitutes a low risk of stroke, not requiring an antithrombotic for stroke prevention?

Answer 23

0 for men and 1 for women.

Question 24

What is amiodarone used for?

Answer 24

Used to alter sinus rhythm to restore a normal heart beat.

Question 25

What are some important side effects one should be aware of with amiodarone use?

Answer 25

Reversible corneal microdeposits, impaired vision, thyroid function, hepatotoxicity, pulmonary toxicity, neurological effects, phototoxic skin reactions.

Question 26

What monitoring is required before and during amiodarone use?

Answer 26

Thyroid function (before and every 6 months), liver function (before and every 6 months), serum potassium (before), chest x-ray (before), ECG with IV use.

Question 27

Why should amiodarone be avoided in pregnancy, unless no alternative is available?

Answer 27

Risk of neonatal goitre.

Question 28

Should amiodarone be used in breastfeeding mothers?

Answer 28

No, present in milk in significant amounts. Theoretical risk of neonatal hypothyroidism from release of iodine.

Question 29

When may drug interactions with amiodarone be seen and why?

Answer 29

Several weeks after treatment cessation due to long half-life.

Question 30

Severe bradycardia and heart block may be seen with the use of amiodarone and which drugs?

Answer 30

Sofosbuvir, daclatasvir, ledipasvir and simeprevir.

Question 31

When used with amiodarone, which drugs show an increased plasma concentration?

Answer 31

Coumarins, dabigatran, digoxin, flecainide, phenindione, phenytoin.

Question 32

When used with amiodarone, which drugs increase the risk of ventricular arrhythmias?

Answer 32

Amisulpride, atomoxetine, chloroquine, citalopram, disopyramide, escitalopram, haloperidol, hydroxychloroquine, levofloxacin, lithium, mizolastine, mefloquine, moxifloxacin, phenothiazines, pimozide, quinine, sulpiride, telithromycin, tolterodine, tricyclics.

Question 33

When given with amiodarone, which drugs increase the risk of bradycardia, AV block and myocardial depression?

Answer 33

Beta-blockers, diltiazem, verapamil.

Question 34

When given with amiodarone, what drug increases the risk of myopathy?

Answer 34

Simvastatin.

Question 35

What is sotalol used for?

Answer 35

To reduce heart rates in arrhythmias.

Question 36

What important safety information should be taken into account when using sotalol?

Answer 36

Can prolong the QT interval, occasionally leading to life threatening arrhythmias.

Question 37

What monitoring is required with sotalol use?

Answer 37

ECG, corrected QT interval, serum electrolytes (K, Mg, Ca). Correct electrolyte disturbances before use.