Arrhythmias Flashcards
What tool is used to diagnose arrhythmias
ECG (underlined)
What is heart rate? Whats a normal resting heart rate?
Frequency of depolarization of the ventricles
Normal resting HR is 60-100 bpm
True or false: all patients experience symptoms of arrhythmias
False
What symptoms can occur w arrhythmias
Dizziness, lightheadedness, shortness of breath, chest pain, fatigue
Describe the 6 phases of ventricular action potential
Phase 0: Na channels open; rapid ventricular depolarization, initiates the heartbeat due to an influx of Na; causes ventricular contraction (QRS complex)
Phase 1: early rapid repolarization, Na channels close
Phase 2: Plateau in response to influx of Ca and efflux of K (calcium in, potassium out)
Phase 3: Efflux of K only (potassium out); rapid ventricular repolarization (T wave)
Phase 4: resting membrane potential, atrial depolarization ocurs (P wave)
Where do class Ia, Ib, and Ic agents work? What agents are in these classes?
In phase 0 where sodium influx occurs
These are sodium channel blockers
Ia: Procainamide, quinidine, dispyramide
Ib: Lidocaine, mexiletine
Ic: flecainide, propafenone
What are class II antiarrhythmics? How do they work?
Beta blockers
Rate control, slow ventricular rate
Also indirectly block calcium channels in the SA and AV node reducing automaticity and conduction velocity
What are class III antiarrhythmics? How do they work?
Potassium channel blockers
Amiodarone
Dronedarone
Sotalol
Define ventricular tachycardia
A series of premature ventricular contractions (PVCs) in a row resulting in a heart rate of greater than 100 bpm, if untreated can progress into ventricular fibrillation which is a medical emergency
What is Torsade de Pointes?
A lethal ventricular tachyarrhythmia which is commonly associated with medications and can result in sudden cardiac death
Prolongation of the QT interval (> 440 milliseconds) is a risk factor for torsades
Whats that stupid mnemonic for the drugs and their drug class
Double Quarter Pounder Lettuce Mayo Fries Please! Because Dieting During Stress Is Always Very Difficult
Ia: Disopyramide, quinidine, procainamide
Ib: Lidocaine, mexiletine
Ic: Flecainide, propafenone
II: Beta blockers
III: Dronedarone, dofetilide, sotalol, ibutilide, amiodarone
IV: Verapamil, diltiazem
Goal HR for patients with symptomatic Afib
< 80 bpm
Lenient strategy of <110 for patients who are asymptomatic and have preserved left ventricular function
Preferred agents for controlling ventricular rate in patients with afib?
Beta blockers (pref’d) and non-DHP calcium channel blockers (verapamil, diltiazem)
Do not use non-DHP calcium channel blockers in pts with HFrEF
What is paroxysmal afib?
Afib that terminates spontaneously or with intervention within 7 days of onset
What is persistent afib?
Continuous afib that is sustained > 7 days
What is long-standing persistent afib?
Continuous afib > 12 months duration
What are class I antiarrhythmics? How do they work?
Sodium channel blockers
Negative inotropic effects
Boxed warning due to increased mortality compared to placebo
Drugs include flecainide, propafenone, lidocaine, mexiletine, procainamide, quinidine, and disopyramide
Class Ia antiarrhythmics: agents, warnings/concerns
Disopyramide (Norpace), quinidine, and procainamide
Disopyramide = Known for strong anticholinergic effects
Quinidine = diarrhea (35%), stomach cramping (22%), cincochism, risk for drug induced lupus, anticholinergic
Procainamide = fatal blood dyscrasias, agranulocytosis, drug induced lupus, hypotension, rash
(ACTIVE metabolite is n-acetyl-procainamide, reduce dose when CrCL < 50 mL/min bc active metabolite is renally cleared (underlined)) - has therapeutic drug monitoring
Class Ib antiarrhythmics: agents, warnings/concerns
Lidocaine
Mexiletine
Only useful for ventricular arrhythmias
Cross the BBB, can cause CNS adverse effects (lightheadedness, dizziness, hallucinations, disorientation)
Which agents are only useful for ventricular arrhythmias?
Class Ib
Lidocaine, mexiletine
Class Ic antiarrhythmics: agents, warnings/concerns
Flecainide, propafenone
Absolutely contraindicated in HF, significant left ventricular hypertrophy, or recent MI (negative inotropic, proarrhythmic properties)
Flecainide: dizziness, visual disturbances
Propafenone: taste disturbances, dizziness, visual disturbances
Class III antiarrhythmics: agents only
Potassium channel blockers
Amiodarone (Pacerone, Nexterone)
Dronedarone (Multaq)
Sotalol (Betapace) - nonselective
Amiodarone boxed warnings, warnings, side effects, notes
Boxed warnings: pulmonary and hepatotoxicity
Warnings: Hyper and hypothyroidism (hypo more common), amiodarone partially inhibits conversion of T4 to T3; optic neuropathy, photosensitivity (slate blue skin discoloration)
Side effects: hypotension, bradycardia, corneal microdeposits, dizziness, ataxia, N/V, constipation, tremor
Notes: Infusions longer than 2 hours must be in a non-polyvinyl chloride (PVC) container such as polyolefin or glass; premixed Nexterone comes in non-PVC containers;
Slow infusion rate of hypotension or bradycardia occur
Half-life: 40-60 days
Antiarrhythmic of choice in heart failure
Amiodarone
