Flashcards in Anti-arrhythmics Deck (26)
A 50 year old woman presents with palpitations and dizziness. She has a Hx of HTN and DM. Her BP is 120/80.
ECG shows AF.
1. DC shock
2. medical cardioversion
3. medical cardioversion + heparin
4. anticoagulation + rate control
4. Patient is stable and there is no precipitating acute illness.
Consider anticoagulation, rate control and or maintenance of sinus rhythm if AF is paroxysmal.
Which of the following is the MOST important risk associated with AF?
2. Left arterial thrombus
4. Chest pain
Left arterial thrombus
5% annual risk of thromboembolic event in persistent / permanent AF
7% risk of thromboembolic event following cardioversion
Thromboembolic risk - CHADS2-VASC score
Congestive heart failure -1
HTN - 1
Age >75 - 1
DM - 1
Stroke / TIA - 2
Vascular disease - 1
Age 65-74 - 1
Sex (female = 1)
Score 0-1 : aspirin
Score 2: oral anticoagulation with either warfarin (INR 2-3) or NOAC e.g. damigatran
How do you calculate bleeding risk?
Hypertension - 1
Age - 1
Abnormal LFTs, renal function 1,1
Stroke / TIA 1
Bleeding risk -1
Labile INRs 1
Score of 3 or more indicates increased 1 year risk of bleed on warfarin sufficient to justify caution or more regular review
Give examples of some new oral anticoagulants
What are the advantages of NOACS?
No monitoring required
What are the disadvantages of the NOACs?
Unable to monitor
Unable to reverse
A 50 yr old woman presents with palpitations and dizziness. She has hypertension and diabetes. Her blood pressure is 120/80.
What is her CHADS2 score and what should we do?
Should prescribe warfarin or NOAC
She is stable so no need to cardiovert. Should rate control - e.g. with beta blocker or CCB
A patient is in acute AF without HF. What drug would you prescribe for rate control?
Beta blocker or CCB (Not both - risk of decreasing HR too much)
2nd line is to add digoxin
A patient is in acute AF with HF. What drug would you prescribe for rate control
2nd line - amiodarone IV
Patient is in paroxysmal AF. what drug would you prescribe for rate control
Beta blocker or CCB
2nd line - add digoxin
DIGOXIN. What is MOA? What is it used for?
Increases vagal tone.
Slows AV nodal conduction
Used for rate control in AF (not PAF) with LVF
Usually well tolerated
Long Half life - 36hrs so need loading dose.
Toxicity with low K+ and high Ca+
Beta blockers - what vaughan-Williams class? What MOA?
Vaughan-williams class II
I SODIUM CHANNEL BLOCKADE
Reduce phase 0 slope and peak of action potential
II BETA BLOCKADE
Block sympathetic activity; reduce rate and conduction
III POTASSIUM CHANNEL BLOCKADE
Delay repolarization (phase 3) and thereby increase action potential duration and effective refractory period
IV CALCIUM CHANNEL BLOCKADE
Block L-type calcium-channels; most effective at SA and AV nodes; reduce rate and conduction
Block B1 and B2 adrenergic receptors
Slow AV conduction
Used in AF rate control and sinus rhythm maintenance. Also used in HTN, IHD etc.
SEs of Beta blockers
Non-dihydropyridine CCBs. Examples? MOA?
Slow AV nodal conduction
Used in AF for rate control and sinus rhythm maintenance. Also used in HTN and IHD
SEs of CCBs such as verapamil and diltiazem
Bradycardia, negative inotrope.
CI - WPW
Drugs for acute cardioversion
Flecainide (rarely used) and sotalol - used for acute cardioversion of a normal heart
Amiodarone - for cardioversion of a structural abnormality
30 yr old patient with no other medical hx presents with palpitations. ECG shows SVT
What drug would you give her?
To terminate the SVT:
1. Carotid sinus massage. Adenosine
2nd line. Beta blocker or CCB
To prevent SVT: Beta blocker or CCB.
or RF ablation
Adenosine. What is it? What is it used for? SEs:
It is a purine agonist with a short half life (10-30s) - causes profound AV block.
Terminated tachycardias involving an AV re-entry circuit (AVNRT or AVRT (WPW))
It is given in fast iv bolus in increasing doses until AV block occurs.
SEs: bronchospasm, flushingg and heaviness in chest
It will terminate AVNRT or AVRT. If patient is in AF or atrial flutter it will reveal the underlying atrial rhythm. If pnt is in VT - it will have no effect.
30 yr old has palpitations. 4 episodes in 1 yr. Each time the ECG shows SVT. What drug would you give her to maintain sinus rhythm
Flecainide or sotalol
Vaughan-Williams - 1c
It blocks Na channels and increases the depolarisation threshold. It is used to cardiovert and maintain sinus rhythm in patients with AF and normal hearts.
SEs = arrythmias.
Class II& III
It is a beta blocker. Blocks cardiac K+ rectifier channel and so slows AV nodal conduction by prolonging the refractory period.
It is used to maintain sinus rhythm in AF with normal hearts. SEs: bradycardia, bronchospasm, negative inotrope + increases QT interval so risk of torsades
55 yr old with previous CABG presents with chest pain and palpitations. BP 70/40 mmHg. ECG shows VT
GCS = 9/15
What would you do?
If pulseless = CARDIAC ARREST - follow ACLS protocol.
If severe compromise - DC shock
If moderate compromise - DC shock or can consider amiodarone IV or Mg IV
In all cases correct reversible causes such as low oxygen and low potassium.
Long term prophylaxis with ICD +/- amiodarone
Amiodarone. What is MOA? What is it used for? SEs?
Vaughan- Williams Class III
Blocks cardiac Na and K channels
Prolongs refractory period
It is used to cardiovert and maintain sinus rhythm in AF, acute VT, VF
Used for VT prophylaxis.
SEs: lung and hepatic fibrosis, hypo/hyperthyroidism, photosensitivity, corneal deposits.
It has a very long half life and therefore needs a loading regimen.
NOTE: it potentiates warfarin
40 yr old woman given IV drug to treat narrow complex tachycardia and felt flushed. Which drug was she given
A 70 year old woman presented with palpitations and shortness of breath. She has acute heart failure: her JVP is raised by 4 cm and she has bilateral crepitations in her chest. An ECG shows AF with a rate of 140 bpm. What drug should be prescribed?
A 50 year old woman presents with irregular heart beat. Her ECG shows AF. She has a history of asthma. On examination she has a normal blood pressure and no signs of cardiac failure. What drug should be prescribed?