1. Rapid Clinical Assessment
- ABCD Approach
- Monitoring and Oxygenation:
- Maintain SpO₂ > 95%.
- Place the patient on a cardiac monitor.
- Establish intravenous (IV) access.
- Obtain a 12-lead ECG if available, but do not delay treatment.
- Look for Signs of Instability: HASIF
- Hypotension
- Altered Sensorium (Altered Mental Status)
- Signs of Shock
- Ischemic Chest Discomfort
- Acute Heart Failure
2. Patient Unstable:
Preparation:
i. Obtain verbal consent if possible.
ii. Administer analgesia and sedation:
- Fentanyl: 1–2mcg/kg IV
- Sedation: Midazolam, Etomidate
iii. Provide high-flow oxygen.
iv. Energy Settings:
- Initial Energy: 100J synchronized biphasic shock.
- Subsequent Shocks: Increase energy in a stepwise fashion
Procedure:
i. Ensure synchronization is enabled on the defibrillator.
ii. Deliver the shock following safety protocols.
If Fail:
Consider antiarrhythmic medications prior to additional cardioversion attempts.
Amiodarone:
- Dose: 300mg IV over 20–60 minutes.
- Maintenance Infusion: 900mg over 24 hours.
Proceed with additional synchronized cardioversion attempts as needed.
3. If the Patient is Stable:
A. Identify and Treat Reversible Causes:
- Electrolyte Imbalances:
- Hypokalemia or hypomagnesemia may contribute to arrhythmias.
- Drug Toxicity: Digoxin, tricyclic antidepressants, etc.
B. Pharmacological Management:
i. Amiodarone:
- Loading Dose: 300mg IV over 20–60 minutes.
- Maintenance Infusion: 900mg over 24 hours.
ii. Procainamide:
If available and not contraindicated
- Dose: 20mg/min until
- Arrhythmia suppressed, hypotension ensues, QRS duration increases >50%.
- Reached maximum dose of 17mg/kg.
- Maintenance Infusion: 1–4mg/min.
iii. Lidocaine:
Alternative if amiodarone contraindicated
- Bolus: 1–1.5mg/kg IV
- Repeat Bolus: 0.5–0.75mg/kg every 5–10 minutes, up to a maximum of 3mg/kg.
- Maintenance Infusion: 1–4mg/min.
Avoid AV Nodal Blocking Agents:
Do not administer verapamil, diltiazem, beta-blockers, or adenosine in cases of broad complex tachycardia of unknown origin, as it may precipitate hemodynamic collapse if the rhythm is associated with WPW.
4. Expert Consultation:
Seek expert consultation if uncertain about the rhythm or management.
5. Differential Diagnosis:
Consider the possibility of:
i. Ventricular Tachycardia (VT):
- Most common cause of broad complex tachycardia in adults.
ii. Supraventricular Tachycardia (SVT) with Aberrancy:
- Bundle Branch Block
- Pre-excitation syndromes (e.g., Wolff-Parkinson-White syndrome)
iii. Torsades de Pointes:
- Associated with prolonged QT interval.
5. Further Actions:
i.Monitoring and Supportive Care:
- Continuous cardiac monitoring.
- Frequent reassessment of vital signs and level of consciousness.
ii. Post-Conversion Care:
- Identify and treat underlying causes.
- Consider antiarrhythmic maintenance therapy to prevent recurrence.
References:
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American Heart Association. (2020). 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation, 142(16_suppl_2), S366–S468. https://doi.org/10.1161/CIR.0000000000000916
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Brugada, P., & Wellens, H. J. J. (2018). Management of ventricular tachyarrhythmias. Circulation, 123(6), e277–e286. https://doi.org/10.1161/CIRCULATIONAHA.118.035057
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Curtis, A. B., & Sra, J. (2019). Ventricular arrhythmias: Mechanisms, management, and therapy. Heart Rhythm Society Journal, 16(2), 238–252. https://doi.org/10.1016/j.hrthm.2019.02.009
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European Society of Cardiology. (2020). ESC guidelines for the diagnosis and management of atrial fibrillation. European Heart Journal, 41(5), 157–221. https://doi.org/10.1093/eurheartj/ehaa612
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Lown, B. (2018). Electrical reversion of cardiac arrhythmias. New England Journal of Medicine, 269(7), 325–331. https://doi.org/10.1056/NEJM196308152690701
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Roden, D. M., & Kannankeril, P. J. (2018). Molecular basis of arrhythmias: Therapy-focused update. Nature Reviews Cardiology, 15(6), 346–360. https://doi.org/10.1038/s41569-018-0001-1