Cario Elective: Ecg Skills Enhancement

ECG Basics

Guide in Reading ECG • • • • • • • • • •

Standardization & technique Rhythm Rate: atrial & ventricular P wave morphology & duration P-R interval QRS complex morphology & duration ST segment T-wave U wave Q-T interval

Normal Intervals Heart rate bradycardia tachycardia PR interval QRS QRS axis QTc

60 - 100 beats/min < 60 > 100 0.12 – 0.20 sec < 0.12 sec - 30º to + 110º < 0.45 sec

ECG Graph paper

Determination of Heart Rate

Heart rate assessment by “rule of 300”

Measurement of Rate • Formula 1:

300 # big squares between R-R

• Formula 2: 1500 # small squares between R-R

Standard Locations of Chest Leads

Determination of Axis

Hexaxial System

QRS axis

P wave morphology

QRS Complex

T wave morphology

Atrial Enlargement

Atrial Enlargement B

V1

II

V1

ATRIAL ENLARGEMENT II

V1

Ventricular Enlargement

RIGHT VENTRICULAR HYPERTROPHY Sokolow-Lyon Criteria: R in V1 + S in V5-V6 > 11 mm R in V1 > 7mm R : S in V1 > 1 RAD > +90 degrees

Additional Criteria: QR in V1 S1 Q3 pattern S1 S2 S3 pattern p pulmonale

Interactive Session

Criteria for Diagnosis of Complete Left Bundle Branch Block • QRS ≥120 msecs • Broad, notched R with prolonged, intrinsicoid deflection in V5, V6 (and I, aVl) • Small initial r waves in V1, V2 followed by deep S waves • Absent septal q waves in left-sided leads

Criteria for Diagnosis of Complete Right Bundle Branch Block • QRS ≥ 120 msecs • Broad, notched R (rsr’, rSR’ pattern) in V1, V2 • Wide and deep S waves in V5, V6 • ST displacement and T waves opposite in direction to the terminal deflection of the QRS complex

Myocardial ischemia and infarction

Myocardial Injury Criteria: 1. Elevation of the origin of ST segment at its junction (J point) with the QRS of: a. >1.0 mm (0.10 mV) in >2 limb leads lasting at least 80 msecs or b. >2.0 mm (0.20 mV) in >2 precordial leads

2. Depression of the origin of ST segment at the J point >1.0 mm (0.20 mV) in at least 2 leads

*ST segment deviation typically either horizontal or slope toward the direction of T waves

Myocardial Infarction Criteria: 1. Development of new Q waves on areas overlying the infarct which is: a. >0.04. secs duration b. >25% of the height of associated R wave

Significant Q wave