Continuing with our theme of using  series of ECGs for teaching, we present the case of an 83-year-old woman with weakness, chest pain, and near-syncope.  The first ECG, taken by paramedics at her home, shows a sinus rhythm with a slightly wide QRS complex.  At this point, it is unclear whether this represents left bundle branch block or a non-specific interventricular conduction delay. There is the most subtle ST elevation in Leads III and aVF. In LBBB without acute M.I., we would expect the ST segments to be discordant, or opposite, the QRS complexes.   Even more informative is the reciprocal ST depression in Leads I and aVL (and a little in V2).  This can be a sign of inferior wall injury that shows up earlier than ST elevation in the inferior leads.

ECG number 2 was taken during transport to the hospital.  The chest pain continues, and now the ST elevation in the inferior leads is pronounced, and the reciprocal depression in I, aVL, and V2 has also become much more obvious.  V1 would also normally show this depression - a sign of the injury traveling up the back of the inferior wall (posterior).  But if the right ventricle is injured, V1 will have ST elevation.    V1 in this case is probably reflecting the depression from the posterior wall AND the elevation from the right ventricle.  The ST elevation is now prominent enough that the paramedics notified the hospital of a "STEMI Alert".  The QRS remains widened at .13 sec., but the ST elevations and depressions are not opposite the QRS direction, which would be typical for LBBB without an M.I.  Therefore, even if LBBB is present, these ST elevations and depressions would be considered a sign of STEMI.  The rate is slowing in this ECG.

ECG number 3 was taken in the Emergency Department.  The patient's symptoms continued.  The bradycardia is still present, as is the QRS widening.  Now, something new has shown up:  prominent U waves in the precordial leads.  There appears to be T-U fusion.  We do not know the patient's medications or lab results, so the most likely cause for the prominent U waves is the bradycardia.  She does not have other ECG signs of hypokalemia, which is one of the many causes of U waves. 

Continuing our teaching series of ECGs donated by Jenda Enis Štros, ECG 4 of 6 shows a new occurance of huge T wave inversions in the precordial leads.  Since this is the area that was stented (left anterior descending artery, anterior wall of the LV), we immediately should think of re-occlusion of the artery.  In a newly-placed stent, the danger is thrombosis (blood clot).  The patient had no chest pain at this time.

Here are links to all six of the ECGs in this series:

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-1-6-acute-anterior-wall-mi

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-2-6-acute-anterior-wall-mi

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-3-6-acute-anterior-wall-mi

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-4-6-acute-anterior-wall-mi

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-5-6-acute-anterior-wall-mi 

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-6-6-acute-anterior-wall-mi

To continue the series donated by Jenda Enis Štros, ECG 2 shows spontaneous resolution of the ST elevation, coinciding with relief of the patient's chest pain.  Spontaneous reperfusion can occur when the artery diameter is increased, the offending clot shifts position to allow blood flow, or other reasons.  This does not mean, however, that the lesion has disappeared.

Here are the links to all six of the ECGs in this series:

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-1-6-acute-anterior-wall-mi

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-2-6-acute-anterior-wall-mi

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-3-6-acute-anterior-wall-mi

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-4-6-acute-anterior-wall-mi

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-5-6-acute-anterior-wall-mi

http://www.ecgguru.com/ecg/teaching-series-1113-ecg-6-6-acute-anterior-wall-mi

This week's ECG for your collection was kindly donated by Dr. Stasinos Theodorou, interventional cardiologist with the Limassol Cardiology Practice in Cyprus. It offers a wonderful teaching opportunity, and illustrates how valuable an ECG can be in locating a lesion during an M.I.   Dr. Theodorou previously posted this ECG and the angiograms from the same patient on FaceBook, and he has offered them to the users of the ECG Guru website  free of copyright.

Dr. Theodorou reports that the culprit lesion in this M.I. was initially very difficult to find on angiogram.  In this case the culprit was an ostially occluded second diagonal artery which, due to the anatomy, was almost impossible to spot from the initial diagnostic images.  There was no "stump" because the occlusion was in the ostium - the beginning of the artery.  The patient also had a significant right coronary artery lesion, but it was not the cause of the M.I. because the RCA perfuses the right ventricle and inferior/posterior wall of the left ventricle.  The ST elevation in this ECG is in I and aVL - the area of the high lateral wall.  Because the  ECG appeared to be inconsistent with the angiogram, Dr. Theodorou obtained further projections, allowing him to identify and treat the offending lesion.  This illustrates the importance of the ECG in locating coronary artery lesions, even in this age of high technology and cath labs.  The interventional cardiologist's proficiency in ECG interpretation enabled him to find this "invisible" lesion.

We are grateful to Dr. Theodorou for sharing this valuable learning experience with us.  You can find more from Dr. Theodorou on his website, FaceBook page, and here, on our "Ask the Expert" page.