Arrhythmias Flashcard 2

D. Rationale: There is a high likelihood of cardiac arrest in a symptomatic child with persistent bradycardia. According to the PALS guidelines for bradycardia, the intervention for poor perfusion and heart rate < 60 beats per minute, despite oxygenation and ventilation, is to give high-quality CPR. When initiated immediately and performed correctly, CPR can double the patient’s chance of survival.

C. Rationale: Part of the training in this PALS course is the decision-making related to defibrillators and their proper use. The rescuer must know when to provide synchronized cardioversion in a patient. Synchronized cardioversion can be performed in unstable patients with supraventricular tachycardia and ventricular tachycardias with a pulse.

B. Rationale: Atropine is indicated for second-degree, third-degree, and complete AV block; cholinergic drug overdose; and increased vagal tone. It is an antimuscarinic and an anticholinergic drug. As a competitive inhibitor of postganglionic acetylcholine receptors, atropine works as a direct vagolytic entity. This leads to increased parasympathetic inhibition that allows for preexisting sympathetic stimulation to predominate, resulting in accelerated sinus and atrial pacemakers, increased atrioventricular conduction, and increased heart rate.

B. Rationale: Adenosine is the drug of choice for SVT. It slows the conduction of the heart in the AV node, thus slowing down the heart rate. It also interrupts the reentry pathway through the AV node, converting SVT back to sinus rhythm. Since the half-life of adenosine is short, it is given in a rapid IV bolus.

Atropine is an anticholinergic agent given to patients presenting with persistent bradycardia with second-degree or third-degree AV block. Amiodarone is the treatment of choice for the pediatric patient with a wide QRS complex tachycardia, such as a probable ventricular tachycardia. It is an antiarrhythmic drug that prolongs the repolarization phase of the cardiac action potential, decreasing calcium permeability and increasing potassium permeability. These actions reduce the automaticity of the SA node, resulting in a reduced heart rate. Epinephrine is given to patients with AV block with persistent and symptomatic bradycardia and those with pulseless arrest (both shockable and non shockable rhythms) despite adequate oxygenation, ventilation, and cardiopulmonary resuscitation.

A. Rationale: Congestive heart failure in infants following a tachyarrhythmia frequently results from SVT. These infants are usually asymptomatic until they present with signs and symptoms of congestive heart failure. They tend to have a history of poor feeding with changes in sleep patterns such as increased sleepiness. On physical examination, they will present tachycardic and in respiratory distress. They will be irritable and are typically pale, mottled, or cyanotic. The result of an untreated SVT is cardiovascular collapse.

B. Rationale: The term bradycardia denotes a slow heart rate when compared with the normal range for a child’s age, level of activity and clinical condition. A neonate has a normal heart range of 100 to 205 beats per minute.

C. Rationale: Transcutaneous or transvenous pacing is a temporary life-saving procedure for patients that are unresponsive to atropine, patients with a third-degree (complete) AV block, and Mobitz type II AV block that is hemodynamically unstable. It is also given to patients with contraindications to atropine, such as those suspected to have myocardial ischemia. Transcutaneous or transvenous pacing is also indicated for patients developing symptomatic AV block after surgical correction of congenital heart disease.

A. Rationale: The initial dose of adenosine is 0.1 mg/kg, with a maximum dose of 6 mg. The second dose can be increased to 0.2 mg/kg, with a maximum dose of 12 mg, if the first dose is ineffective. Successful cardioversion to sinus rhythm after adenosine administration should occur in 30 seconds following a brief period of bradycardia, complete AV block, or even asystole. Because of its relatively short half-life, adenosine needs to be given in a rapid IV bolus. A common cause of cardioversion failure from adenosine is from providing the bolus too slow. Adenosine slows down the conduction time in the AV node, and interrupts reentrant circuit or any other accessory pathway in the AV node, reverting supraventricular tachyarrhythmia to sinus rhythm. Adenosine has limited use in atrial flutter, atrial fibrillation, or any other tachyarrhythmia with no AV node reentry.

A. Rationale: Congestive heart failure in infants frequently results from supraventricular tachycardia. Infants with SVT are usually asymptomatic until congestive heart failure ensues. These patients are irritable and are pale, mottled or cyanotic. They have a history of poor feeding, with changes in sleep patterns such as increased sleepiness. On physical examination, they have tachycardia, and are in respiratory distress. The result of an untreated supraventricular tachyarrhythmia is cardiovascular collapse.

A. Rationale: The PALS guidelines recommend giving adenosine at a dose of 0.1 mg/kg followed by a second dose of 0.2 mg/kg if the first dose is ineffective; with a maximum single dose of 6 mg on the first dose and 12 mg on the second. Successful cardioversion to sinus rhythm should occur within 30 seconds following a brief period of bradycardia, complete AV block, or even asystole. Because of its relatively short half-life, adenosine needs to be given as a rapid IV bolus. A common cause of cardioversion failure from adenosine is from administering the bolus too slowly. Adenosine slows down AV node conduction time and interrupts the reentrant circuit or any other accessory pathway in the AV node, reverting SVT to sinus rhythm. Adenosine has limited use in atrial flutter, atrial fibrillation, and any other tachyarrhythmia with no AV nodal reentry.