Arrhythmias Flashcards
Describe the negative inotropic effects of anti-arrhythmic drugs. What extra care is needed due to this feature?
They tend to be additive. Care is needed when using two or more, especially if myocardial function is impaired.
Define inotrope.
An agent which alters the force or energy of muscle contractions.
Describe the difference between positive and negative inotropes.
Positive inotropes increase the strength of muscular contractions whilst negative inotropes decrease the force of muscular contractions.
Which electrolyte imbalance can affect the pro-arrhythmic nature of many drugs?
Hypokalaemia.
What treatment should be used for life-threatening, new-onset atrial fibrillation?
Emergency electrical cardioversion.
Define electrical cardioversion.
The use of electricity to return the heart to a regular rhythm.
If new-onset atrial fibrillation is not life-threatening, what should be used to return the heart rhythm to normal?
Pharmacological or electrical cardioversion.
What can be used as monotherapy to control ventricular rate?
A standard beta-blocker or a rate limiting calcium-channel blocker (e.g. diltiazem or verapamil).
Which beta-blocker should not be used for the control of ventricular rate?
Sotalol.
If monotherapy for ventricular rate control does not achieve the desired result, what can be used as dual therapy?
A beta-blocker, digoxin or diltiazem.
Define sinus rhythm.
Cardiac rhythm with depolarisation beginning at the sinoatrial node.
How can sinus rhythm be maintained post-cardioversion?
With a standard beta-blocker.
If a standard beta-blocker can’t be use to maintain sinus rhythm after cardioversion, what alternatives can be used?
Sotalol, flecainide, propafenone or amiodarone.
Verapamil should be avoided in patient’s on beta-blockers. Why?
Increased risk of severe hypertension and asystole.
What length of time should atrial fibrillation be present for before electrical cardioversion is preferred?
48 hours +.
How long should a patient be fully anticoagulated for before and after electrical cardioversion?
At least 3 weeks before and 4 weeks after.
What should all patients with atrial fibrillation be assessed for?
Their stroke risk and their need for thromboprophylaxis.
What does an AF patient’s risk of stroke and need for thromboprophylaxis need balancing with?
Their bleeding risks.
What score is used to determine the stroke risk of a patient with AF?
CHADSVASC.
What score is used to determine a patient’s risk of bleeding?
HASBLED.
What are the risk factors used to determine a patient’s CHADSVASC score?
Congestive heart failure, hypertension, age greater than 75 years, age between 65-74, diabetes mellitus, vascular disease, stroke/TIA/thromboembolism, gender (female).
What are the risk factors used to determine a patient’s HASBLED score?
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).
What CHADSVASC score constitutes a low risk of stroke, not requiring an antithrombotic for stroke prevention?
0 for men and 1 for women.
What is amiodarone used for?
Used to alter sinus rhythm to restore a normal heart beat.
What are some important side effects one should be aware of with amiodarone use?
Reversible corneal microdeposits, impaired vision, thyroid function, hepatotoxicity, pulmonary toxicity, neurological effects, phototoxic skin reactions.
What monitoring is required before and during amiodarone use?
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.
Why should amiodarone be avoided in pregnancy, unless no alternative is available?
Risk of neonatal goitre.
Should amiodarone be used in breastfeeding mothers?
No, present in milk in significant amounts. Theoretical risk of neonatal hypothyroidism from release of iodine.
When may drug interactions with amiodarone be seen and why?
Several weeks after treatment cessation due to long half-life.
Severe bradycardia and heart block may be seen with the use of amiodarone and which drugs?
Sofosbuvir, daclatasvir, ledipasvir and simeprevir.
When used with amiodarone, which drugs show an increased plasma concentration?
Coumarins, dabigatran, digoxin, flecainide, phenindione, phenytoin.
When used with amiodarone, which drugs increase the risk of ventricular arrhythmias?
Amisulpride, atomoxetine, chloroquine, citalopram, disopyramide, escitalopram, haloperidol, hydroxychloroquine, levofloxacin, lithium, mizolastine, mefloquine, moxifloxacin, phenothiazines, pimozide, quinine, sulpiride, telithromycin, tolterodine, tricyclics.
When given with amiodarone, which drugs increase the risk of bradycardia, AV block and myocardial depression?
Beta-blockers, diltiazem, verapamil.
When given with amiodarone, what drug increases the risk of myopathy?
Simvastatin.
What is sotalol used for?
To reduce heart rates in arrhythmias.
What important safety information should be taken into account when using sotalol?
Can prolong the QT interval, occasionally leading to life threatening arrhythmias.
What monitoring is required with sotalol use?
ECG, corrected QT interval, serum electrolytes (K, Mg, Ca). Correct electrolyte disturbances before use.
