ECG in a prone patient

A case report in Prehospital Emergency Care describes an obese (>200 kg) chest pain patient who refused to lie supine because of severe back pain. A 12 lead ECG was done with all the leads placed posteriorly, and the resultant electrocardiograph showed characteristic ST elevation in II, III and AVF with ST depression in AVL. The inferior MI was confirmed in hospital on repeat ECG, biomarker rise, and a thrombus in his right coronary artery at angiography.

Abstract A prehospital 12-lead electrocardiogram (ECG) is commonly used for patients with suspected ST-segment elevation myocardial infarction (STEMI). This case report describes how paramedics diagnosed inferior STEMI with all ECG leads positioned on a patient’s back (i.e., “all-posterior” positioning). The patient was hemodynamically stable but morbidly obese and markedly diaphoretic. Owing to severe back pain, he refused to lie in the supine position for assessment or transport. At the emergency department, a 12-lead ECG with the patient in lateral recumbency confirmed the diagnosis of inferior STEMI. This case shows that an all-posterior 12-lead ECG can be used to identify STEMI when optimal patient positioning is not possible.

Prehospital Diagnosis of ST-segment Elevation Myocardial Infarction Using an “All-Posterior” 12-Lead Electrocardiogram
Prehosp Emerg Care. 2011 Jul-Sep;15(3):410-3

4 thoughts on “ECG in a prone patient”

  1. Very sharp thinking on their part! This is why it is important to know not only what you’re looking at on an ECG, but what it really means. Moving electrodes is just another set of eyes on the problem.

  2. I would love to see an ECG. Doing a posterior ECG could show posterior wall involvement which is usually associated with an Inferior MI. Did they make there diagnosis off of a posterior MI and assumed that an IWMI was associated with it?

  3. Nicely done. The ST segment vector during RCA occlusion is known to be oriented essentially along the craniocaudal axis. Body surface potential maps recorded over the entire torso clearly show its dipole nature with the negative potential encircling the upper thorax and positive potential encircling the waist, but parallel shifted slightly toward the sternum so anterior potentials are larger than those on the back. Since the vector lies almost strictly in the frontal plane, precordial and posterior leads are normal and irrelevant, provided it is an inferior STEMI. Limb leads are identical either way. The ECG should be the same regardless of front or back for an inferior MI, which this case report confirmed. BSPM studies during coronary occlusion have also shown that LAD and LCx ischemia each have their voltage peaks (negative and positive respectively) at roughly the same left infrascapular region used here, but of opposite sign to the precordium. Therefore totally reasonable alternative to use the posterior lead set.

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