Arrythmias Flashcards
Sinus bradycardia
ONLY TREAT IF SYMPTOMATIC
HR < 60
Impulses in the SA node
Decrease automaticity in the SA node
Hypotension, dizziness, fainting
Atropine 0.5-1 mg every 5 minutes, max of 3 mg if symptomatic
SE of atropine: tachycardia, constipation, dry mouth, blurred vision, urinary retention
OR: dopamine, epinephrine, isoproterenol
PACEMAKER if unwilling for pacemaker then theophylline
Atrial fibrillation
chest pains, palpitations, dizziness, light headedness, SOB, hypotension, angina, fatigue, HF exacerbation
Goal #1 is to prevent thrombosis leading to a stroke: anticoagulants
Goal #2 is to control ventricular rate: Non-DHP CCB, BB, Digoxin, Amiodarone
Goal #3 convert to NSR: ibutilite, amiodarone, procainamide, flecainide, propafenone, DCC
Goal #4 is to maintain NSR and to prevent recurrent episodes: dronedarone, dofetilide, flecainide, propafenone , amiodarone, sotalol
Ventricular rate: 120-180 bpm
Supraventricular tachycardia (SVT)
Types: paroxysmal SVT
Features: regular rhythm
HR: 110-250 bpm
Narrow QRS complexes
Single re-entry circuit in the AV node moving in a circular motion depolarizing ventricles but travelling back up to repolarize atria
Can also occur in the AV pathway, atria, and SA node
Neck pounding, palpitations, dizziness, lightheadedness, polyuria, syncope
Goal #1 Terminate SVT
Adenosine: 6-12-12
Diltiazem
Verapamil
BB
Premature ventricular complexes (PVC)
Widened QRS complex
NSR with occasional abnormal beats
Types:
Simple: isolated single PVC
Frequent: at least 1 PVC on a 12-lead ECG or > 30 PVCs/hour
Risk factors: ischemic heart disease, MI, anemia, hypoxia, cardiac surgery
Usually asymptomatic, palpitations, dizziness, lightheadedness
Treatment:
asymptomatic PVC should not be treated
BB, verapamil, diltiazem, cardiac ablation
Ventricular tachycardia
MONOMORPHIC TACHYCARDIA
Regular Rhythm
Wide QRS complex
HR: 100-250
Series of > 3 consecutive PVC’s at a rate > 100 bpm
Types: non-sustained, sustained, sustained + no structural heart disease
Mechanism: increase automaticity, re-entry within the ventricles
Risk factors: MI, CAD, HFrEF, electrolyte imbalance, drugs such as flecainide, propafenone, digoxin
Symptoms: asymptomatic (nonsustained VT), palpitations, dizziness, lightheadedness, angina, syncope, hypotension
Goal 1: Terminate VT, restore NSR
DCC is preferred, then procainamide, then IV Amiodarone or sotalol
verapamil and BB is for no structural heart disease
Goal 2: prevent recurrence and sudden cardiac death
- Implantable cardiac defibrillator (ICD)
outflow tract VT: BB
Ventricular fibrillation
Irregular, disorganized, chaotic electrical activity
No recognizable QRS complexes
Risk factors: MI, HFrEF, CAD
Symptoms: syndrome of sudden cardiac death
Goal: Terminate VF, restore NSR
The only effective treatment is defibrillation
Drugs are used to facilitate defibrillation
Drugs alone with not terminate VF
Defibrillation, Epinephrine, Amiodarone, Lidocaine
Defibrillation, CPR, DRUG–> repeat
How to read an ECG
P wave: atrial depolarization
QRS complex: ventricular depolarization, atrial repolarization is buried
T wave: ventricular reploarization
PR interval: conduction time of AV node
QT interval: repolarization
How to determine NSR
Is there a p wave in front of every QRS complex?
Is there a QRS complex after every p wave?
Is the interval between the R waves equal?
Is there HR between 60-100 bpm?
Normal ECG values
PR interval: 0.12-0.20 seconds (120-200 ms)
QRS duration: 0.08-0.12 seconds (80-120 ms)
QT interval: 0.38-0.46 seconds (380-460 ms)
QTc interval: 0.36-0.45 seconds (360-450 ms) – Men
QTc interval: 0.36-0.46 seconds (360-460 ms) - Women
Torsades de pointes
POLYMORPHIC TACHYCARDIA
When QTc > 0.5 seconds–> increased risk of drug-induced arrhythmia
What does QTc interval mean?
Corrected QT interval for HR
Slower HR: Longer QTc
Fater HR: slower QTc
Medications that can cause TdP
Antiarrhythmics
Macrolides, fluoroquinolones
Antidepressants, antipsychotics
Amiodarone
MOA: all 4 antiarrhythmic mechanisms
Both BB and CCB activity
AE: Hypotension, bradycardia, pulmonary fibrosis, blue/grey skin discoloration, corneal deposits, hepatotoxicity, hypothyroidism, photosensitivity
Drug interactions:
Inhibits Pgp: digoxin
Inhibits CYP: warfarin, statins
Monitoring: Dermatologic, corneal deposits, pulmonary fibrosis, QTC prolongation, hepatotoxicity, hypo,hyperthyroidism
Goal HR < 100-110 bpm and asymptomatic
Hemodynamically unstable criteria
SBP < 90
HR > or equal to 150 bpm
Loss of consciousness
Chest pain
ALWAYS USE DCC
Ibutilide
Class 3 antiarrhythmic blocking Ikr channel
AE: TdP
DO NOT USE IN HF
NEGATIVE INOTROPE
Procainamide
Class 1A blocking both sodium and potassium channels
AE: QTc prolongation, hypotension TdP, HF exacerbation, Agranulocytosis, Neutropenia
Drug interactions: inhibited by cimetidine, ranitidine, trimethoprim
DO NOT GIVE IN HFREF
NEGATIVE INOTROPE
Flecainide
Class 1C blocking sodium channel
AE: dizziness, blurred vision, HF exacerbation
DO NOT GIVE IN HFREF
NEGATIVE INOTROPES
Propafenone
class 1C blocking sodium channel
dizziness, blurred vision, HF exacerbation
DO NOT GIVE IN HFREF
NEGATIVE INOTROPES
Dronedarone
Maintain NSR
Class 3 blocking Ikr channel
T1/2 is 18 hours: remove iodine atoms reducing toxicity, no interaction with warfarin, amiodarone is more effective
AE: bradycardia, nausea, diarrhea, asthma, rash
Drug interactions:
Inhibits elimination of: simvastatin, digoxin, verapamil, diltiazem, dabigatran
inhibited by: ketoconazole, itraconazole, ribavirin, grapefruit juice
Dofetilide
Must be initiated in hospital for 3 days to undergo ECG monitoring for risk of QT prolongation and TdP
MOA: Class 3 blocking Ikr channel
AE: TdP
Drug interactions: cimetidine, thiazides, trimethoprim, verapamil, ketoconazole
Sotalol
Must be initiated in hospital for 3 days to undergo ECG monitoring for risk of QT prolongation and TdP
Class 2 and 3
AE: QTc prolongation, TdP, hypotension, bradycardia
Catheter ablation
Indication: used for patients who did not respond to antiarrhythmic drugs, contraindicated, not tolerated or preferred.
Can be 1st line therapy in younger patients with fewer comorbidities who are experiencing paroxysmal atrial fibrillation
Mapping
Ablation
AE: pulmonary vein stenosis
BB
Direct AV node inhibitor
Sinus bradycardia, SA/AV node block, sinus arrest, HF exacerbation (low EF)
Diltiazem
Direct AV node inhibitor
AE: hypotension, lightheadedness, dizziness, bradycardia, SA/AV node block, HF exacerbation
Inhibits CYP3A4: cyclosporine, statins
Verapamil
Direct AV node inhibitor
AE: hypotension, lightheadedness, dizziness, bradycardia, SA/AV node block, HF exacerbation, constipation
Inhibits CYP3A4: cyclosporine, statins
Inhibits Pgp: digoxin, dofetilide
Dofetilide dose
Proceed only if QTc < or equal to 440
CrCl > 60: 500 mcg po BID
CrCl 40-60: 250 mcg po BID
CrCl 20-39: 125 mcg po BID
CrCl < 20: contraindicated
Sotalol dose
Proceed only if QTc < or equal to 450
CrCl > 60: 80 mg po BID
CrCl 40-60: 80 mg po daily
