Appendix C 12-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 Placement Precordial 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) Gail Walraven, Basic Arrhythmias, Seventh Edition ©2011 by Pearson Education, Inc., Upper Saddle River, NJ