STEMI

Question 1

Where to measure ST segment elevation

Answer 1

-from isoelectric line to J point
-count how many little squares there are (in mm) between isoelectric line and J point

Question 2

Coronary artery structure

Answer 2

-2 main coronary arteries= right and left coronary artery
-left divides into left anterior descending artery (LAD) (supplies front of heart) and left circumflex artery (wraps around the back supplying the left ventricle
-RCA divides into posterior descending artery supply R atria and ventricle and wraps around the back of the heart supplying the posterior

Question 3

Diagnostic criteria (pathway 1)

Answer 3

-ST elevation (2mm in chest leads, 1mm in limb leads) in 2 or more leads that look at same view of the heart
-ST depression in V1-3 with ST elevation in V7-9
-left coronary mainstem- greater than 1mm depression in 6 leads and ST elevation in aVR

Question 4

What part of the heart ECG leads look at and reciprocal changes

Answer 4

Lateral leads
- I, aVL, V5, V6 - reciprocal= II,III, aVF
Inferior leads
- II,III, aVF - reciprocal= I, aVL
Septal leads
- V1-V2 - reciprocal= V7-V9
Anterior leads
- V3-V4 - reciprocal= V7-V9

Question 5

Posterior electrode placement

Answer 5

-V7- left posterior axillary line, same horizontal plane as V6
-V8- tip of left scapula
-V9-paraspinal region left, same horizontal line
ONLY USED TO DIAGNOSE POSTERIOR STEMI, IF NO ST ELEVATION BUT ST DEPRESSION IN 1,2,3

Question 6

Right ventricular infarction in patients with inferior STEMI
What ECG changes we’d expect

Answer 6

-ST elevation in V1
-ST elevation in V1 and ST depression in V2
-isoelectric ST segment in V1 with marked depression in V2
-ST elevation higher in lead 3 when compared to lead 2
-diagnosis confirmed with ST elevation in V4R (move V4 to right of chest)

Question 7

Why its important to identify right ventricular infarct in inferior STEMI

Answer 7

-pre load sensitive due to poor RV contractility
-cause severe hypotension due to GTN or morphine
-therefore if inferior STEMI be careful when administering GTN or morphine

Question 8

Left coronary mainstem diagnosis criteria

Answer 8

-greater than 1mm depression in 6 leads
-and ST elevation in aVR and/or V1
-not actually a full occlusion as otherwise pt would be dead