Arrhythmias Flashcard 3

D. Rationale: The PALS guidelines recommend giving an initial energy dose of 0.5 to 1 joule per kg body weight to cardiovert supraventricular tachyarrhythmia or ventricular tachycardia with a pulse. If this dose fails, then it may be increased to 2 joules per kg bodyweight. The succeeding dose may be increased by an experienced provider.

D. Rationale: An initial energy dose of 0.5 to 1 J/kg of bodyweight is recommended for pediatric cardioversion. If this dose fails, then the dose may be increased to 2 J/kg. An experienced provider may increase the succeeding dose.

B. Rationale: The PALS guideline recommends giving an IV bolus of atropine at a dose of 0.02 mg/kg to be repeated after 5 minutes (with a maximum single dose of 0.5 mg) for patients suffering from second-degree AV block, third-degree AV block, complete AV block, cholinergic drug overdose, or increased vagal tone. Atropine is a competitive inhibitor of postganglionic acetylcholine receptors with a direct vagolytic effect. This leads to an increased parasympathetic inhibition, which allows for preexisting sympathetic stimulation to predominate, resulting in accelerated sinus and atrial pacemakers, increased atrioventricular conduction, and increased heart rate.

D. Rationale: Atropine is used for persistent bradyarrhythmia’s to improve vagal tone or primary atrioventricular block. Atropine should be considered if the patient has not improved after performing CPR for 2 minutes and if the cause of bradycardia is due to second-degree or third-degree AV block, an increase in vagal tone, or cholinergic drug overdose.

C. Rationale: Vagal maneuvers increase the vagal tone and thus lower the heart rate. For infants and children who cannot follow instructions, placing an ice-cold bag to the child’s face for 15–30 seconds at a time should cause efferent stimulation of the vagus nerve, slowing the conduction rate at the AV node. For children who can follow instructions, they can bear down (Valsalva maneuver), or blow through an occluded straw. For older children, carotid massage may be done to stimulate the vasovagal response.

C. Rationale: Magnesium sulfate decreases automaticity and suppresses ventricular arrhythmias, which are primarily seen in patients with hypomagnesemia and torsade’s de pointes. Torsade’s de pointes is a type of polymorphic ventricular tachycardia with a varying amplitude that seems to twist along the isoelectric line. Left untreated, it may spontaneously convert to sinus rhythm or a cardiac arrest rhythm such as ventricular fibrillation and lead to asystole.

C. Rationale: The treatment of choice for unstable tachyarrhythmias with a pulse is synchronized cardioversion. Adenosine is the treatment of choice for stable supraventricular tachycardia

A. Rationale: Atropine is used for the treatment of bradycardia secondary to increased vagal tone, cholinergic drug toxicity, or complete atrioventricular block.

A. Rationale: Atrioventricular blocks are bradyarrhythmia’s that may be due to conduction defects brought about by congenital heart diseases, electrolyte imbalances, or the result of hypoxia, hypotension, and shock. Conduction defects may also be iatrogenic in nature, e.g., after cardiac surgery.

D. Rationale: Torsade’s de Pointes is a polymorphic ventricular tachycardia which is treated with magnesium sulfate. It has the propensity to deteriorate into ventricular fibrillation. Defibrillation is not indicated for Torsade’s de Pointes unless it converts to ventricular fibrillation. Asystole and pulseless electrical activity are non shockable rhythms.