STEMI-44

Published: February 27th, 2016

Category: STEMI

Emergency Department ECG:

STEMI1

Right-Side ECG:

STEMI2

* Patient has history of CABG.  Right side ECG shows ST elevation in V4R indicating possible R ventricular involvement

Cardiac Cath Report:

LMCA:  Patent, gives rise to the LAD and LCX.

LAD: 100% mid occlusion.  Diagonal with long 80% stenosis.  Distal AD fed by LIMA and is patent to the apex.  No competitive flow noted to any graft.

LCX: Proximal 80% stenosis, large OM1 with 85% stenosis, ongoing LCX is small and occluded.  No competitive flow noted to any graft.

RCA: Large, dominant, 95% mid stenosis with thrombus, TIMI 2.5 flow, distal RCA with 50% lesion beyond site of plaque rupture, patent right PDA.

PLAN: Successful stent placement in mid RCA

Teaching:

  • Right side MI
    • Complicates 40% of inferior MIs
    • Right ventricle is preload dependent which may lead to hypotension if Nitroglycerin is administered.  Treat with IV fluids and rapid transport.
  • Right side ECG
    • A complete set of right-sided leads is obtained by placing leads V1-6 in a mirror-image position on the right side of the chest (see diagram, below).
    • It may be simpler to leave V1 and V2 in their usual positions and just transfer leads V3-6 to the right side of the chest (i.e. V3R to V6R).
    • The most useful lead is V4R, which is obtained by placing the V4 electrode in the 5th right intercostal space in the midclavicular line. ST elevation in V4R has a sensitivity of 88%, specificity of 78% and diagnostic accuracy of 83% in the diagnosis of RV MI
  • Inferior MI
    • 40-50% of all myocardial infarctions.
    • more favorable prognosis than anterior myocardial infarction
    • Up to 40% of patients with an inferior STEMI will have a concomitant right ventricular infarction. These patients may develop severe hypotension in response to nitrates and generally have a worse prognosis.
      • Confirmed with Right sided ECG, Elevation in V4R
    • Up to 20% of patients with inferior STEMI will develop significant bradycardia due to second- or third-degree AV block. These patients have an increased in-hospital mortality (>20%).
  • ECG findings
    • ST elevation in leads II, III and aVF
    • Reciprocal ST depression in aVL (± lead I)
    • RCA (80%): Elevation in III > II, Reciprocal depression in I
    • LCx (20%): Elevation in III = II, No reciprocal depression in I

Right Side ECG:

right-ventricular-leads.gif