Cardiology

Question 1

When and how to do RV ECG leads (when considering RV infarct)?
What is the significance?

Answer 1

Inferior wall ischaemia: ST elevation in II, III, aVF
(especially if STe in III > II)

STe in V1 (esp if STe in V1 > in V2)
or
Isoelectric or STe V1, but STd in V2

These changes are seen with left- or right-sided lead placement.

(R)-sided leads: Place leads on (R) side of chest (in mirror image).
V4R most useful: 5th ICS, MCL. STe in V4R highly suggestive of RVi.

RV infarct –> pre-load sensitive (poor RV function)
Nitrates contraindicated as they reduce preload –> hypotension
Fluid loading is indicated for hypotension

Question 2

When to suspect Posterior Infarct. Lead placement. Significance?

Answer 2

Inferolateral STEMI
Posterior extension (ie. LARGE infarction) suggested by changes in V1-V3:
- ST depression (horizontal / down sloping)
- Tall, broad R waves (>30ms)
- R:S >1 in V2
- upright T waves
(i.e. opposite to usual STEMI signs, as viewing from anterior position).

Posterior leads V7-V9:
All same plane as V6
V7 = (L) posterior axillary line
V8 = below (L) scapula tip
V9 = (L) paraspinal

Note: only need 0.5mm STe in posterior leads to Dx posterior STEMI!