Should we activate the lab? A simple but important lesson

Written by Pendell MeyersA man in his 60s called EMS for sudden chest pain and shortness of breath. He was found in moderate respiratory distress, hypertensive, diaphoretic, and hypoxemic. He was given aspirin, nitroglycerin, and placed on noninvasive positive pressure ventilation during transport. Medics recorded a 12-lead and transmitted it to the provider, asking if they wanted to activate the cath lab.Here is the ECG:What do you think?Sinus rhythm. In this EMS ECG, as is true for many EMS ECGs, the machine cuts off the S wave voltage at 10 mm. You can see this visually by the subtle but noticeable squared-off waveform of the S wave in leads V2-V3.In lead aVL, you can see that the machine does not limit the R waves to 10 mm. So as far as I can tell, this machine only limits negative QRS voltage to 10 mm. In limiting the S wave to 10 mm, this feature of the EMS 12-lead ECG significantly changes the visual proportionality of the ST segments and T waves in the affected leads. If this QRS were only 10 mm or less in amplitude, then these STEs and relatively large T waves in leads V1-V4 could be worrisome for anterior OMI.But after falling for this trick once, you probably will not make this mistake again. You will see easily that this QRS shows significant voltage and morphology of LVH.So the provider said no, no prehospital cath lab activation for now and we will evaluate the patient immediately on arrival.The patient arrived and was already much improved from the paramed...
Source: Dr. Smith's ECG Blog - Category: Cardiology Authors: Source Type: blogs