ECG

Dr. Amal Al MaqadmaTeaching assistant

IUG

MIWhen myocardial blood supply is abruptly reduced toa region of the heart, a sequence of injurious eventsoccur:

Ischemia ( subendocardial or transmural)

Injury Necrosis, and eventual fibrosis

(scarring) if the blood supply isn't restored in an appropriate period of time

Hyperacute T wave is the earliest sign of acute myocardial infarction

Precordial Septal Leads

V1 – V2

– Look at the Septum of the heart

– The septal branch of the

LAD

Precordial Anterior Leads

V3 – V4

–anterior wall of the left ventricle

– The LAD diagonal branch )

Anterior-Septal Terminology

Lateral Precordial Leads

I,AVL,V5 – V6

lateral of the left ventricle

The left circumflex

Inferior border leads

II, III and aVF the Inferior wall

of the RV Posterior

Descending Branch of the RCA.

Posterior MI No leads look at the posterior wall.

usually associated with inferior and/or lateral wall MI. The changes of posterior myocardial infarction are seen

indirectly in the anterior precordial leads. Leads V1 to V3 face the endocardial surface of the posterior wall of the left ventricle. As these leads record from the opposite side of the heart instead of directly over the infarct, the changes of posterior infarction are reversed in these leads. The R waves increase in size, becoming broader and dominant, and are associated with ST depression and upright T waves. This contrasts with the Q waves, ST segment elevation, and T wave inversion seen in acute anterior myocardial infarction.

ST depression is considered reciprocal ECG changes in what should be ST elevation for acute posterior wall injury.

ECG Leads - Views of the Heart

leadborderArterial supply

V3 & V4anterior Right Ventricle

RCA

V1 & V2SeptumLAD

a VL,V5 & V6Lateral Left Ventricle

LCX

II+III+AVFinferior borderof right ventricle

RCA

Principles of ECG recording

Explain the indication and the procedure for the patient. (assurance )

Ask the patient to take off any metals he/she wears.

Expose the wanted sites. Cleaning of skin and shaving if necessary. Place the electrodes in the correct positions . Instruct the patient to remain still (should not

talk during the test ) and relax their shoulders and legs while the recording takes place (1 min)

See video

How to comment on ECG

Name.Age ,Date and time. Calibration and Speed of paper RAWIHI :

RAWIHI

R: rate, regularity,rhythm(sinus or asinus),

A: axis. W:waves. I :intervals. H: hypertrophy. I: ischemia

Normal Sinus Rhythm Rate = 60-100 beat / minute. The rhythm is regular All intervals are within normal limits There is a P for every QRS and a QRS for

every P. P : QRS ratio = 1 : 1. The P waves all look the same Presence of P, QRS, T in each cycle. Normal shape, time of waves, segments

and intervals

Interfering factors Inaccurate placement of the electrodes Electrolyte imbalances Poor contact between the skin and the electrodes Movement or muscle twitching during the test

Drugs that can affect results include digitalis, quinidine, and barbiturates