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Dr. Ajith Kumar J MD
Dept. of Emergency Medicne
KIMS, Kollam
India
editor@emmedonline.com

ACS & ECG

DIAGNOSIS

ECG

		CHARACTERISTICS
STEMI	ST elevation	ST elevation in 2 or more contiguous leads. J point elevation greater than 2mm in V2,V3* & 1mm or more other leads. *: males <40 yrs 2.5 mm ; females 1.5mm
High risk UA/NSTEMI	ST depression or dynamic T-wave inversion	ST segment depression ≥0.5mm or dynamic T- wave inversion with pain or discomfort. Non persistent or transient ST elevation for <20 min .
Intermediate or low risk UA	Normal or non diagnostic ECG	Non specific ST/T changes

Q waves and Territory Involved

Anteroseptal	QS deflections in V1,V2,V3 & possibly V4
Anterior	rS deflection in v1 with Q waves in V2-V4 or decrease in amplitude of initial R wave in V1-V4.
Anterolateral	Q waves in V4-V6,I & aVL
Lateral	Q waves in I & aVL
Inferior	Q waves in II,III, aVF
Inferolateral	Q waves in II,III,aVF ,V5,V6
True posterior	Tall R waves in V1 & V2; R/S ratio ≥1 with ST depression
Right ventricular	Q waves in II,III & aVF & ST elevation in right side V4.

Lateral Wall MI : ECG shows ST segment elevation of Lead I, aVL and reciprocal change ST segment depression in III, aVF.

Anteroseptal MI :ECG shows ST elevation in V1 - V4.

ST elevation in II, III, avF with ST depression in I,aVL and RBBB

In inferior wall MI always take a right side chest leads so as to look for an right ventricluar infraction. This is because autopsy studies on patients with an inferiopposterior infract found that one out of four cases had involenement of right ventricles.

POINTS TO REMEMBER

Loss of normal R wave progression in the chest leads is suggestive of anterior wall infraction.
QS pattern in V1,V2 is suggestive of anteroseptal infraction enerally occurring from occlusion of left anterior descending coronary artery.
QS or QR pattern in V2, V3 is suggestive of anterior infract generally occurring from occlusion of left anterior descending coronary artery.
QS or QR pattern in V5, V6 is is suggestive or anterolateral or anteroapical infraction due to occlusion of left circumflex coronary artery.

qs in v1,v2,v3 suggestive old anterior wall ischemia; with t wave inversion in v5,v6, left axis deviation

POINTS TO REMEMBER

The right coronary artery supplies both the inferior portion of heart and right ventricles.
Left anterior descending coronary artery supplies the ventricular septum and a large part of the left ventricular free wall.
Left circumflex coronary artery, supplies the lateral wall of the left ventricle.

What is J point ?

It is the junction of QRS complex and ST segment.

ST SEGMENT DEPRESSION

ST segment depression usually represents subendocardial ischemia.
A horizontal or downward ST depression of at least 1mm or more lasting 0.08 sec as a positive result.
ST segment depression with a rapid upward sloping of st segment are considered negative.

POINTS TO REMEMBER

The anterior and inferior leads tends to show inverse patterns.
Thus in anterior infraction with ST segment elevations in two or more of V1 to V6 , I, and aVL, ST segment depression is seen in lead II, III , aVF.
It is seen conversely in inferior wall infraction.

A : Planar ST is usually indicative of myocardial ischemia B: Down Sloping depression is also indicative of myocardial ischemia C: Upsloping depression may be a normal finding.

Updated on 24/8/13

Reference :

Goldberger
ECG Made Easy by John Hampton
Tintinalli

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emmedonline
Dr. Ajith Kumar J MD
Dept. of Emergency Medicne
KIMS, Kollam
India
editor@emmedonline.com

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ACS & ECG

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