When an Inferior Wall MI is identified (ST segment elevation in II, III, aVF) perform a right-sided 12 lead EKG. To do this, move V4 to the right side (same anatomical position as normal 12 lead, just on the right side of the sternum) and obtain another 12 lead.
When the new 12 lead prints, look specifically in lead V4 for any ST segment elevation of greater than 1mm. If there is elevation, this is indicative of a Right Ventricular Infarction (RVI). Then, take a pen (yes, you need to carry a pen) and put a giant "R" next to the V4 on the new, right-sided 12 lead EKG - this will help you and the receiving facility know which 12 lead print out was is the "normal" 12 lead and which is the right-sided 12 lead.
So, why do we do this? Well, it’s because of the coronary artery anatomy…let’s take a look!
Look at the picture above, the Right Coronary Artery ultimately supplies the Posterior Descending Artery and the Right Marginal Artery.
The Posterior Descending Artery supplies the inferior wall.
The Right Marginal Artery supplies the right ventricle.
When an Inferior Wall MI is identified, a right-sided 12 lead occurs in an attempt to identify if the occlusion is happening in the posterior descending artery alone (point A) or if it is happening in the proximal RCA (point B) – which would cause infarctions of both the inferior wall and the right ventricle.
When the right ventricle is involved, we are concerned with preload and nitroglycerin administration.
When a RVI is found, use caution with nitroglycerin. Instead, consider a fluid bolus to support preload (Starling’s Law), aspirin, and oxygen.
-Pass with PASS