Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Gail Walraven

Basic ArrhythmiasSeventh Edition

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Appendix C12-Lead Electrocardiography

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Rule of Electrical Flow

• Current flowing toward a positive electrode creates an upright deflection.

• Current flowing toward a negative electrode creates a downward deflection.

• When the lead is at right angles to the current, the line is isoelectric (neither upright nor downward).

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Lead

• A combination of electrodes that reflects flow of electricity between two points on opposing sides of the heart.

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Leads

• Bipolar leads have one positive and one negative electrode.

• Unipolar leads have a positive electrode, but the opposing electrode is created by combining other electrodes into a central terminal, an electrically neutral point situated to reference the center of the heart.

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Electrode Placement for MCL1

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Frontal and Horizontal Planes

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Electrode Placement – Frontal Plane

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Standard Lead Lines

• Lead I: right arm to left arm

• Lead II: right arm to left leg

• Lead III: left arm to left leg

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Standard Limb Leads

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Augmented Leads

• aVR:central terminal to right arm

• aVL: central terminal to left arm

• aVF: central terminal to left leg

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Augmented Limb Leads

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Frontal Plane Leads

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Frontal Plane Leads

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Horizontal Plane Leads

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Electrode PlacementPrecordial Leads

• V1: right sterna border, fourth intercostals space

• V2: left sterna border, fourth intercostals space

• V3: midway between V2 and V4

• V4: midclavicular line, fifth intercostal space

• V5: anterior axillary line, fifth intercostal space

• V6: midaxillary line, fifth intercostal space

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Vector

• The arrow used to indicate direction and magnitude of electrical flow.

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Lead Axis

• An imaginary line from the positive electrode to the negative electrode for each lead, depicted by an arrow (vector).

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Mean QRS Axis

• The axis of the heart as a whole; the aggregate of all the electrical vectors in the heart.

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Lead Axis vs.Mean QRS Axis

• When the two are parallel, the deflections are either positive or negative.

• When the two are perpendicular, the complexes are biphasic.

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

EKG Deflections

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Wave Definitions

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Frontal Plane Vectors

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Horizontal Plane Vectors

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Mean QRS Axis

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Estimating QRS Axis

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Standard Layout of 12-Lead EKG

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Features of a Normal 12-Lead EKG

• All waves upright (except aVR)

• Small Q waves in lateral leads (I, aVL, V6)

• T waves in V1-V6 should be smooth, gradual

• T wave: positive, negative, or biphasic in V1; positive in V2–V6

• QRS transition from V1 (small R, large S) to V6 (small Q, large R), roughly equiphasic in V3(V4)

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Normal 12-Lead Wave Forms (Example 1)

Gail Walraven, Basic Arrhythmias, Seventh Edition©2011 by Pearson Education, Inc., Upper Saddle River, NJ

Normal 12-Lead Wave Forms (Example 2)