ECGs by diagnosis

ST depression in 2,3 avf is usually due to high lateral ST elevation (I, aVL) (although the STE may not be seen clearly, esp in aVF (QRS vector is perpendicular to aVF) , just ischemia

Commonly held belief that you can localize where ischemia is when its ST depression is NOT true.... be more concerned that you're seeing reciprocal changes

ST segment elevation is relative to QRS size!

Early repol vs STEMI - STEMI has longer QT interval, less R wave amplitude, and more ST elevation - single best differentiator is R wave amplitude -one of hallmarks of early repol is well formed R wave in V2-V4 -- if have QS wave + ST elevation must consider: Old MI vent aneurysm subacute aneurysm 12hr old and R wave has disappeared Cardiomyopathy LVH

you can get qR waves immediately after MI - this does not mean that infarction has occurred and there's no point in reperfusion (that's what a QS wave means)

avL is the clue to whether the inf leads ST elevation represent inf MI or don't (ST depression OR TWI) ..... if you think this pt has an inf wall MI but there's nothing in aVL you're probably wrong

QRS > 200 think hyperK

Arrythmias

See Cards: Arrythmias (DDX)

MI

1. T wave usu tracks w/ the QRS, thus if QRS primarily negative, twi is not necessarily abnl (nl twi in V1).
2. ST elevation non-specific, also w/ LVH & strain, LBBB, CA spasm, pericarditis, "early repol", hyperK, dig/TCA's, CVA, Vent. aneurysm, hypothermia.
3. Non-transmural: ST dep at least 1.0mm, twi.
4. II, II, AVF for inf. MI
5. V1-3 for anteroseptal inf.
6. I, AVL, V4-6 for lat. wall inf.
7. V1 or V2-6 anterolat.
8. Large R and ST depression in V1-V2= POST. INFARCT! Post MI usu seen w/ inf MI b/c RCA supplies both in 90% of pts!
9. Pts w/ inf. infarction +/or post wall mi often also have RV mi, need R sided leads!!
10. STE >/= 1mm in V3R or V4R suggest RV MI!
11. STE > 2wks= poss vent aneurysm!
12. STE in avR and avL = LMA stenosis
13. STE in avR and V1 = LAD or LMA stenosis
14. if STE > 1.5 mm in avR pt has 75% mortality from AMI --> activate cath lab (unless pt is in SVT, then STE is allowed)

Infarct notes

1. inf wall: recip. In 1 and AVl. Downward sloping ST in AVl is often first sign.
2. Any ST depression in V1 to V3 in a LBBB is pathological and suggestive of a post. Wall MI.
3. Poor r waves progression-no r's by V4
4. persistent t-wave elevation 6 wks post mi-vent. Anyeursm.anteroseptal with biphasic/inverted t wave

Pericarditis

See Pericarditis#ECG

Electrolyte Disorders

HyperK

1. 5.5-6.6 -> tall peaked T, deep S in I and V6, QRS nml
2. 7.0-8.0 -> QRS widens, slurred initial and term QRS, ST elevation, low wide P's, AV blocks, SA arrest, bradycardia.
3. >8.0 -> widened QRS, Vfib, asystole.

HypoK

1. 3.0-3.5 no change or flat T' sand U's in V2-3, QT interval and QRS nml.
2. 2.7-3.0 U taller, T smaller, esp. V2-3
3. <2.6 ECG change includes tall U's, QT and QRS wnl.

HyperCa

1. Increased QRS duration (slight)
2. ST short or absent
3. Short corrected QT.
4. PR long

HypoCa

1. slight decrease in QRS.
2. ST and corrected QT long
3. PR short.
4. T's flat to inverted.

CNS

1. SAH, IC bleed, stroke, can see diffuse wide deep, blunted inverted T's. and QT prolonged

Pacemakers

1. Should be in the apex of R vent.
2. ECG should mimic LBBB, w/ L axis.

PE

1. S1Q3T3
   1. (good specificity, poor sensitiviy)

Source

DONALDSON 17/09 (Adapted from Niemann/Lampe)