Ventricular fibrillation and defibrillation

Significance of automated external defibrillator in identifying lethal ventricular arrhythmias

Automated electrical defibrillator (AED) is critical in saving children who develop unexpected cardiac arrest (CA), but its diagnostic capacity is not fully acknowledged. Retrospective cohort study of patients with aborted sudden cardiac death (SCD) was performed. Twenty-five patients (14 males) aged 1.3 to 17.5 years who presented with CA survived with prompt cardiopulmonary resuscitation. Eighteen patients had no prior cardiac diagnosis. Cardiac arrest occurred in 10 patients with more than moderate exercise, in 7 with light exercise, and in 8 at rest (including one during sleep). Twenty-two patients were resuscitated with AED, all of which were recognized as a shockable cardiac rhythm. Thorough investigations revealed 6 ion channelopathies (4 catecholaminergic polymorphic ventricular tachycardia, one long QT syndrome, and one Brugada syndrome), 5 congenital heart disease (including 2 with coronary artery obstruction), 6 cardiomyopathies, 2 myocarditis, and 2 miscellaneous. Four patients had no identifiable heart disease. In 5 patients, the downloaded AED-recorded rhythm strip delineated the underlying arrhythmias and their responses to electrical shocks. Four patients who presented with generalized seizure at rest were initially managed for seizure disorder until AED recording identified lethal ventricular arrhythmias.Conclusions: AED reliably identifies the underlying lethal ventricular arrhythmias in addition to aborting SCD. What is Known: • Although infrequent in children, sudden cardiac death (SCD) is often an unexpected and tragic event. The etiology is diverse and sometimes remains unknown despite extensive investigations. • Automated external defibrillator (AED) is both therapeutic in aborting SCD and diagnostic in identifying the underlying lethal ventricular arrhythmias. However, the diagnostic aspect of AED is under-acknowledged by most medical providers. What is New: • Four of 25 patients (16%) were initially managed for possible seizure disorders until AED recording identified lethal ventricular arrhythmia. • The AED recording of the lethal arrhythmia during cardiopulmonary resuscitation (CPR) should always be obtained as it plays a crucial role in the decision-making process before ICD implantation. All medical providers should become familiar with downloading cardiac rhythm strips from AED when requested.

[National evaluation of knowledge and practice of cardiopulmonary resuscitation of children and infants in the field]

INTRODUCTION

After the publication of new recommendations for cardiopulmonary resuscitation (2005 guidelines and 2006 French recommendations), we conducted a study amongst EMS teams concerning their approach with children and infants, nationwide. The objective was to measure the level of knowledge of guidelines and practice.

METHODS

The online questionnaire was offered to emergency physicians belonging to the French emergency database, between November 1st and December 15th 2007. Incomplete questionnaires were excluded from the study. We recorded: profile of personnel, knowledge of guidelines, basic CPR and advanced CPR parameters.

RESULTS

Four hundred and thirty-nine questionnaires were analyzed. Personnel was aged under 40 in 50.2 %, with 2-5 years experience in prehospital emergency care (57.6 %); 51,3 % declared having had training in pediatric CPR. A minority of subjects declared knowing the 2005 Guidelines (35 %), more the French 2006 recommendations (62.5 %). Basic CPR: transition age child/adult known in 30.3 %. Compression/ventilation ratio: 30/2 for one rescuer in 50.2 % (child), 46.5 % (infant); 15/2 for two or more rescuers in 57.6 % (child), 48 % (infant). AED age for use (1 year old) known in 59.8 %. Advanced CPR: epinephrine dose known in 89.3 % (intravenous) and 34.3 % (tracheal). External shock known in 57.2 %.

CONCLUSION

This study emphasizes the lack of knowledge, especially with regard to first aid. Formations will be developed.

Elevated impedance during cardioversion in neonates with atrial flutter

Direct-current cardioversion is a common treatment modality for acute termination of atrial flutter in neonates. Studies in children have demonstrated that cardioversion is often successful with as little as 0.25-0.5 J/kg with the current biphasic devices. We hypothesize that during cardioversion of atrial flutter in neonates, however, the impedance may be high and more energy may be required for successful cardioversion. A retrospective chart review of our institutional experience from 2005 through 2008 was performed. Neonates with atrial flutter requiring cardioversion who had strips available for review were included. Six patients met the inclusion criteria. The median age at the time of cardioversion was 2.6 h (range, 1.3-336 h) and the mean weight was 3.22 +/- 0.4 kg (SD). The mean electrical impedance of the successful shocks was elevated, at 234 +/- 136 Omega. The mean energy delivered for successful cardioversion was 0.9 +/- 0.3 J/kg, and the current was 1 A in all patients. In conclusion, the shock impedance was elevated in the neonates studied during cardioversion of atrial flutter. Low current was sufficient for successful cardioversion. Further studies are needed in this specific population.