ECG The Basics And Beyond Anita Ralstin MS, FNP-BC

I have no conflicts of interest.

Pearls Treat the patient not the paper. Electrical activity triggers mechanical activity. No electrical activity = no mechanical activity But electrical activity does not guarantee mechanical activity. The more cells involved the larger the deflection on the ECG. If the wave of electrical activity is moving toward the electrode, the wave will be positive (above the baseline); if the wave is moving away from the electrode the wave will be negative (below the baseline).

Cardiac Conduction System normal ECG One small box = .04 seconds One large box = .20 seconds Conduction picture courtesy of New Mexico Heart Institute

Anatomy and the ECG The P wave = atrial activation (SA node to AV node). The PR interval = onset of atrial activation to onset of ventricular activation. The QRS complex = electrical ventricular activation. The ST-T segment = ventricular repolarization. The QT interval = the duration of ventricular activation and recovery.

Calculation Of Heart Rate Method 1: Count the number of large (0.2-second) time boxes between two successive R waves, and divide the constant 300 by this number OR divide the constant 1500 by the number of small (0.04-second) time boxes between two successive R waves. Method 2 best for irregular rhythms: Count the number of cardiac cycles that occur every 6 seconds, and multiply this number by 10.

The Rule Of 300 It may be easiest to memorize the following table: # of big boxes Rate 1 300 2 150 3 100 4 75 5 60 6 50

Calculation Of Heart Rate

Question Calculate the heart rate

Definition of Normal Sinus Rhythm Heart rate 60-100 Adult 80-160 Infant 80-130 Toddler 75-115 6 year old Regular rhythm P waves round, same shape and before each QRS Normal PR interval (0.12-0.20 sec or 3-5 small boxes) Normal QRS interval (< 0.12 sec or < 3 small boxes) QRS positive in leads I, II, aVF, V3-V6

Cardiac Conduction System normal ECG Conduction picture courtesy of New Mexico Heart Institute

Where Does The Impulse Come From? Electrical Impulse Formation Initiation Point Rate Regularity Onset SA Node, Atrial, Junction, Ventricles Normal, Tachycardic, Bradycardic Regular, Irregular, Irregularly irregular Passive escape, active

Where/How Does The Impulse Travel? I, II, III RBBB Electrical Impulse Conduction Sinus Node Atria AV Junction Ventricular SA Block Intra Atrial Block LBBB LAH, LPH Complete, Incomplete

Combined Flow Sheet Initiation Point Formation Rate Regularity Onset I, II, III RBBB Conduction Sinus Node Atria AV Junction Ventricular SA Block Intra Atrial Block LBBB LAH, LPH Complete, Incomplete Electrical Impulse Formation Initiation Point Rate Regularity Onset SA Node, Atrial, Junction, Ventricles Normal, Tachycardic, Bradycardic Regular, Irregular, Irregularly irregular Passive escape, active

Sinus Rhythm The P wave is upright in leads I and II Each P wave is usually followed by a Q The heart rate is 60­-100 beats/min

When Is The Rhythm Unstable Four main signs Signs of low cardiac output – systolic hypotension < 90 mmHg, altered mental status Excessive rates: <40/min or >150/min Chest pain Heart failure If unstable, electrical therapy: cardioversion for tachyarrhythmia, pacing for bradyarrhythmia

Review Of Common Rhythms 1. Normal Sinus Rhythm 2.

Review Of Common Rhythms 3. 4. Supraventricular Tachycardia

Review Of Common Rhythms 4. 6. Atrial Flutter 5.

Review Of Common Rhythms 6. 8. 2nd Degree AV Block Type 1 (Wenckebach)

Cardiac Conduction System normal ECG Conduction picture courtesy of New Mexico Heart Institute

Review Of Common Rhythms 7. 10. 8.

Cardiac Conduction System normal ECG Conduction picture courtesy of New Mexico Heart Institute

Review Of Common Rhythms 9.

Review Of Common Rhythms 10.

Review Of Common Rhythms 11. 12.

Cardiac Conduction System normal ECG Conduction picture courtesy of New Mexico Heart Institute

Thank you Questions?