Arrhythmias Flashcards
1
Q
Normal Conduction Pathway
A
- Impulse begins in SA node
- Travels from SA node to left/right atria, contraction
- Reach AV node which slows down the conduction
- Continues into Bundle of His and into ventricles
- Bundle of His divides into right/left bundle branches for the right/left ventricles
- Spreads through ventricles via Purkinje fibers, contraction
2
Q
Phases of Action Potential
A
- Phase 0: rapid ventricular depolarization via influx of Na+, ventricular contraction (Class I mainly works here)
- Phase 1: early rapid repolarization (Na channels close)
- Phase 2: plateau in response to Ca+ influx and K+ outflux
- Phase 3: rapid ventricular repolarization from K+ efflux, ventricular relaxation (Class III works here)
- Phase 4: Resting membrane potential established, atrial depolarization occurs
3
Q
Classes of QT Prolonging Medications
A
- Antiarrhythmics: Class I (Ia) and III
- Antibiotics: quinolones and macrolides
- Azoles (minus isavuconazonium)
- Antidepressants: TCAs, SSRIs, SNRIs
- Antiemetics: 5HT3 antagonists, droperidol, phenothiazines
- Antipsychotics (most of them)
- Other: Donepezil, fingolimod, methadone, tacrolimus
4
Q
Double Quarter Pounder, Lettuce, Mayo, Fries, Please! Because Dieting During Stress Is Always Difficult
A
- Class I: a) Disopyramide, Quinidine, Procainamide; b) Lidocaine, Mexiletine; c) Flecainide, Propafenone
- Class II: B-Blockers
- Class III: Dronedarone, Dofetilide, Sotalol, Ibutilide, Amiodarone
- Class IV: Verapamil, Diltiazem
5
Q
Class I MOA
A
- Na-channel blockers
- Proarhythmic (higher risk of arrhythmia)
- Caution in patient with underlying cardiac disease
6
Q
Class II MOA
A
- B-blockers
- Blocks sympathetic nerve activity that can trigger arrhythmia
- Mainly used to slow ventricular rate in Afib
7
Q
Class III MOA
A
- K-channel blockers
- Amiodarone and dronedarone also block Ca and Na channels and alpha/beta receptors
- Amiodarone useful for many arrhythmias, including Afib
- Amiodarone and dofetilide are preferred for Afib patient with HF
8
Q
Class IV MOA
A
- Ca-channel blockers, non-DHP CCB
- Slow ventricular rate in Afib
- Don’t use in patients with HFrEF
9
Q
Digoxin MOA
A
- Na-K-ATPase blocker
- Decreases heart rate by increasing vagal tone
- Positive inotrope (force of contraction)
10
Q
Adenosine MOA
A
- Activates adenosine receptors to reduce AV node conduction
- Used for PSVTs (paroxysmal supraventricular tachyarrhythmias)
11
Q
Nexterone
A
- Amiodarone, LONG half life
- Box Warnings: pulmonary tox, hepatotox, proarrhythmic (life-threatening)
- CI: iodine hypersensitivity
- Warnings: hypo/hyperthyroid, optic neuropathy, pale slate blue skin, neuropathy
- Non-PVC container needed (this brand is in one)
- 0.22 micron filter needed, central line preferred
12
Q
Non-DHP CCBs
A
- Diltiazem (Cardizem, Tiazac) and Verapamil (Calan SR)
- Don’t use in HF patients, may worsen sxs
- SE: Edema, arrhythmia, constipation (verapamil more so), gingival hyperplasia
- Don’t use DHP CCBs for arrhythmias
13
Q
Digoxin
A
- Typical dose: 0.125-0.25 mg PO QD
- Decrease dose 25-50% PO to IV
- Decrease dose or frequency when CrCl < 50
- Therapeutic range for Afib: 0.8-2
- Initial toxicity: N/V, loss of appetite, bradycardia
- Severe toxicity: blurred/double vision, green/yellow halos
- Antidote: DigiFab
- Hypokalemia/magnesemia and HYPERcalcemia increase tox risk
14
Q
Disopyramide
A
- Class Ia drug
- Anticholinergic effects
- Proarrhythmic
15
Q
Quinidine
A
- Class Ia drug
- Take with food or milk
- DILE and hemolysis risk (G6PD deficiency)
- SE: diarrhea, stomach cramping, cinchonism (overdose) - hearing/vision loss, HA
16
Q
Procainamide
A
- Injection
- Active metabolite = NAPA (antiarrhythmic) and is renally cleared
- Box warning: agranulocytosis, DILE risk
- Slow acetylators are at risk for toxicity/accumulation
17
Q
Lidocaine
A
- Class Ib
- Injection
- Used for refractory VT/cardiac arrest
18
Q
Flecainide
A
- Class Ic
- Proarrhythmic
- CI: HF and MI
19
Q
Propafenone
A
- Class Ic
- Proarrhythmic
- CI: HF and MI
- SE: Metallic taste disturbance
20
Q
Dronedarone
A
- Class III
- Box Warning: increased risk of death/stroke/HF in patients with decompensated HF (class IV) or permanent AFib
- CI: CYP3A4 inhibitors or QT prolonging drugs
- Warning: Hepatic failure, pulmonary disease/fibrosis
- No iodine contained
- SE: QT prolongation
21
Q
Betapace
A
- Sotalol (can’t interchange with Betapace AF)
- Class III
- Non-selective B-blocker
- Decrease frequency at CrCl < 60
- QT prolongation directly related to [sotalol]
22
Q
Ibutilide
A
- Class III
- Injection
- Correct hypokalemia/magnesemia before use and during treatment
23
Q
Dofetilide
A
- Class III
- Box warning: must be used with continuous ECG monitoring and assessment of CrCl for at least 3 days
- Proarrhythmic!!
- Drug of choice in HF
24
Q
Adenosine
A
- Injection
- Half life of <10 sec
- Used in PSVTs
25
Q
Afib Rate Control Options
A
- B-blockers
- Non-DHP CCBs (CI: HF)
- ADD-on: Digoxin
26
Q
Converting Rhythm Control Options
A
- Amiodarone
- Dofetilide
- Flecainide
- Ibutilide
- Propafenone
27
Q
Afib Maintaining Rhythm Options
A
- Dofetilide
- Dronedarone
- Flecainide
- Propafenone
- Sotalol
28
Q
Amiodarone DDI
A
- Decrease warfarin by 30-50%
- Decrease digoxin by 50%
- Don’t exceed 20 mg simvastatin
- Don’t exceed 40 mg lovastatin
- Sofosbuvir - bradycardia risk (CI)
- *MANY DDI - inhibits many CYPs/Pgp**
