|Wide complex tachycardia of unknown etiology.|
A 12-Lead was obtained and interpreted as presumed ventricular tachycardia:
|Wide complex tachycardia, interpreted as presumed ventricular tachycardia.|
Given the presence of a WCT with hemodynamic instability the patient was prepped for synchronized cardioversion. Combo-pads were placed anterio-laterally, the Sync button was pressed, and sync markers were noted with each QRS complex.
The patient was then synchronized cardioverted at 100J biphasic:
|100J synchronized cardioversion.|
|Ventricular fibrillation post cardioversion.|
|200J defibrillation of ventricular fibrillation.|
In this case the paramedic did not appreciate that oversensing was present from the cardiac monitor's display. It was not until after the summary printed that the ineffective synchronization was discovered.
|Oversensing during synchronized cardioversion--highlighted in red--resulting in therapy delivery during the vulnerable period.|
|Illustration of the vulnerable period of ventricular repolarization. Adapted from Reilly et al. 1998 pp 188 Fig 5.19.|
|A prolonged QT interval and an "R-on-T" PVC resulting in Torsades de Pointes. Used with permission from Dr. Ken Grauer's ECG Web Brain.|
|Oversensing of atrial fibrillation. Adapted from Resuscitation 82 (2011):135-136,Fig.1.|
- Reilly J. Patrick. Applied Bioelectricity: From Electrical Stimulation to Electropathology. Springer-Verlag: New York (1998); pp 188.
- Dr. Ken Grauer's ECG Web Brain. Accessed online 26 July 2012. [https://www.kg-ekgpress.com/]
- Sodeck GH, Huber J, Stollberger C. Letter to the Editor: Electrical cardioversion - Misinterpretation of the R-wave. Resuscitation 82 (2011): 135-136. [PubMed]