Tachyarrhythmias Flashcards
PAC characteristics
- Early atrial depolarization
- Bigeminal or trigeminal
- P wave morphology may be different
SVT characteristics
- Narrow QRS complex at 140-240 bpm
- Abrupt onset/offset
- P wave buried in QRS
What causes SVT?
An accessory pathway
What terminates SVT?
Adenosine
AV re-entry tachycardia: Normal conduction/sinus steps
- Conduction occurs normally through atrium
2. Accessory pathway conducts to ventricles & AV node
AV re-entry tachycardia: Tachycardia activation steps
- Premature beat arrives while accessory is still refractory
- Slowly activates AV node
- By the time the signal reaches the ventricle, accessory pathway has recovered & is able to transmit signal to atria
- Atria reactivates ventricle via AV node
Concealed pathway
SVT via an accessory pathway, but has normal EKG
WPW characteristics
- SVT via accessory pathway & has delta wave on resting/sinus EKG
- Pre-excitation of ventricle in the location of accessory pathway, while conducting through AV node
- Narrow PR interval
WPW definition
Must have SVT, sx, & delta wave on EKG
AVNRT: Dual AV nodal physiology
- Slow pathway (fast recovery)
- Fast pathway (slow recovery)
AVNRT: Initiation of tachycardia
- Normal impulse conducted
- PAC occurs (conducted via slow pathway bc fast pathway is refractory)
- PAC reaches end of slow pathway –> fast pathway is recovered –> transmits signal to atria
Atrial tachycardia characteristics
- Originates within atria, but outside sinus node
- Bc rate is faster than sinus rate, it takes over as main pacemaker
- Rate of 140-220, rarely sustained for long periods
- P wave often buried within T wave
- Not terminated by adenosine
- May require meds if symptomatic
Multifocal atrial tachycardia
- Multiple ectopic foci in atria firing –> multiple p wave morphology
- HR: 100-150
- Transitional arrhythmia from AT to AF
What is the most common cause of COPD?
MAT
AF characteristics
- Ventricular rates are usually fast, over 100
- No discernable p waves
What is the most common chronic arrhythmia?
AF
How do you tx AF?
- Rate control
- Stroke prevention
- DCCV
- Anti-arrhythmics
AF carries a risk of what?
CVA (evaluate w/ CHADS score)
Atrial flutter characteristics
- “Saw tooth” in inferior leads (II,III, & aVF)
- Short re-entrant circuit within RA (conducting at 300bpm)
- Usually regular ventricular response (150bpm)
Atypical atrial flutter
re-entrant circuit in the atria from any other location in the atria
Atrial flutter carries a risk of what?
CVA (anticoagulation = prevention)
How do you tx atrial flutter?
- Anticoagulation
- Ablation
- Anti-arrhythmics
PVC characteristics
- Wide QRS w/out preceding P wave
- Bigeminal or trigeminal
What can PVCs cause?
Palpitations
How do you treat PVCs?
- Beta blocker
- Calcium channel blocker
- Ablation if sx/cardiomyopathy
VT characteristics
- 3 or more consecutive PVCs (160-200bpm)
- Nonsustained: more than 3 beats but less than 30 seconds before terminating spontaneously
- Sustained: over 30 seconds &/or requiring DCCV
How do you tx VT?
Based on hemodynamic stability
- Stable: IE beta blockers, anti-arrhythmics
- Unstable: cardiovert emergently
Monomorphic VT
Due to re-entrant circuit within ventricle (caused by MI scar)
Polymorphic VT
- Omnious, indicating more electrically unstable/irritable ventricle
- See Review 8a
Wide complex tachycardia
- VT or aberrantly conducted SVT
- Dx via cardiology/EP
How do you tx wide complex tachycardia?
Tx as VT until proven otherwise
- If unstable, tx w/ DCCV
Torsades de Pointes characteristics
- Polymorphic VT (long QT interval)
- Twisting of QRS complex along isoelectric baseline
- Also occurs in complete heart block
How do you tx Torsades de Pointes ?
- Emergent defibrillation
- Leads to sudden cardiac death
- Magnesium after defibrillation
VF characteristics
- No discernable ventricular activity (200-300bpm)
- Pulseless
How do you tx VF?
- Causes death unless quickly resuscitated (next step = asystole)
- Requires defibrillation ASAP
Indications for ICD
- EF less than 35%
- Previous cardiac arrest in absence of reversible cause