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Tachycardia Algorithm Review Romulo B. Babasa III, MD. 1. Case Scenario.
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Tachycardia Algorithm Review Romulo B. Babasa III, MD 1
Case Scenario An 34-year-old came into the ER complaining of chest tightness and palpitations, which roused her from sleep. She had cold, clammy skin and pallor. Vital signs were HR = 154 bpm; BP =100/70 mm Hg; RR = 24 rpm. Full and equal pulses. Rhythm: see next slide.
34-Year-Old Woman:Tachycardia • Identify A, B, and C • Which one is most likely to be her rhythm? A B C
Rhythms to Learn • Sinus tachycardia • Narrow QRS • Regular • Supraventricular tachycardia (SVT) • Junctional tachycardia • Ectopic atrial tachycardia • Wolff-Parkinson-White (WPW) • Irregular • Atrial fibrillation • Atrial flutter
Rhythms to Learn • Wide QRS • Regular • Ventricular Tachycardia • Irregular • Torsades de Pointes
Synchronized Cardioversion • The purpose of cardioversion is to deliver a precisely timed electrical current to the heart to convert an organized rhythm to a more hemodynamically stable rhythm • Supraventricular tachycardia, atrial flutter, atrial fibrillation, and WPW syndrome
Defibrillation • The purpose of defibrillation is to deliver a randomly timedigh-energy electrical current to the heart that is fibrillating to restore a normal sinus rhythm • Ventricular tachycardia, ventricular fibrillation
VagalManeuvres These maneuvres increase the vagal tone that have been shown to slow conduction and prolong the refractory period in the AV node: • Carotid sinus massage – exert pressure on the carotid sinus and baroreceptors against the transverse process of C6 • Valsalva maneuvre
Adenosine • Endogenous nucleoside produced by the degradation of adenosine triphosphate (ATP) • Slows cardiac conduction and restores sinus rhythm by transient AV nodal block • Rapidly metabolized by most cells • Very short half-life (<10 seconds)
Adenosine • Onset of action: 20-30 seconds • Duration of action: 60-90 seconds • Indication: - for emergency treatment of SVT (supraventricular tachycardia)
Adenosine • Dosage: - initial dose of 6mg rapid IV bolus (1-2 sec) - may be repeated 2x with 12mg after 1-2 mins - followed immediately by a 10-20ml fluid flush - elevate the arm to maximize distribution - if infused slowly, can cause systemic vasodilation and a reflexive tachycardia
Adenosine • Pediatric dose: 0.1-0.2 mg/kg • Possible adverse effects: - well tolerated because they last <1minute - most common: - dyspnea, vertigo, headache, numbness - facial flushing, chest pain, palpitation
Amiodarone • Antiarrhythmic agent (Class III) • Delays repolarization by prolonging the action potential duration and effective refractory period. • Amiodarone slows the heart by impairing SA nodal function, depressing AV nodal conduction, modifying the automaticity of spontaneously firing fibers in the Purkinje system, and prolonging the refractory period in an accessory pathway (e.g., WPW syndrome).
Amiodarone • Dosage: - VF/pulseless VT: 300mg IV bolus may be repeated with 150mg - other dysrhythmias: 150mg IV in 100ml D5W x 10 minutes infusion: 1 mg/min for 6 hours 0.5 mg/min thereafter - Pediatric dose: 5mg/kg over 20-60 minutes
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