Chapter 23. Electrocardiography

• Screening for congenital or acquired heart disease.

• Follow-up of established cardiac disorders:

• • Progression of chamber enlargement.

  • Hypertrophy.

  • Conduction disorders.

  • Ischemic changes.

• Evaluation of apparent life-threatening event, syncope, chest pain, or new-onset seizure.

• Arrhythmia detection and evaluation.

• Evaluation of conduction disorder.

• Monitoring cardiac effects of medication.

• Evaluation for appropriate pacemaker or defibrillator function.

• Evaluation of cardiac effects of electrolyte or metabolic abnormalities.

• Disorders that limit access to skin of chest wall, such as thoracic wound.

• Extensive bandages over chest.

• Third-degree skin burns.

• ECG machine, leads.

• Electrode stickers; pediatric patches are best.

• Alcohol pads to clean skin.

• Improper electrical grounding may deliver electrical shock; extremely rare.

• Improper lead positioning is a major source of abnormal tracings.

• • Results in repeat ECGs or unnecessary further testing.

  • As many as 15–20% of pediatric ECGs performed in emergency departments or intensive care units show improper lead placement.

• The most common recording error is limb lead reversal.

• • White electrode should be on right arm.

  • Black electrode should be on left arm.

• Automated ECG interpretations that read “left atrial rhythm” usually reflect limb lead reversal.

• Negative P, QRS, and T waves in leads I and aVL are another indicator of lead reversal.

• Make sure the initial recording is at the appropriate speed: 25 mm per second, and appropriate gain: 10 mm per mV.

• Eliminating as much patient movement as possible is essential; blowing bubbles over young children often allows time for recording without movement.

• Clean the area with alcohol swab.

• Skin must be clean and dry.

• Leads cannot be placed over bandages: either reposition bandage or omit lead.

• Supine position is essential.

• Some patients have T wave changes in upright positions, and decubitus positioning may slightly alter the location of the heart relative to the ECG leads.

• Lead placement is important and must be consistent.

• Inappropriate placement of limb or precordial leads results in interpretation errors, including hypertrophy or infarct patterns.

• Figure 23–1 shows placement of leads.

• • RA: Right forearm, distal to insertion of deltoid muscle.

  • LA: Left forearm, distal to insertion of deltoid muscle.

  • RL: Right leg.

  • LL: Left leg.

  • V1: Fourth intercostal space, right sternal edge.

  • V2: Fourth intercostal space, left sternal edge.

  • V3: Halfway between V2 and V4.

  • V4: Fifth intercostal space, midclavicular line.

  • V5: Same level as V4 on anterior axillary line.

  • V6: Same level as V4 on midaxillary line.

• Place electrode stickers appropriately.

• Attach the leads, with careful attention to limb lead placement.

• Enter the patient data into the ECG machine. ECGs without name, age, and ...