Basic Rhythm Recognition Lecture Notes

Introduction to Cardiac Rhythms

• Primary Pacemakers: Cells with automaticity, able to spontaneously depolarize.
  • Sinus Node: Primary pacemaker, fires at 60-100 bpm.
  • AV Junction: Fires at 40-60 bpm.
  • Ventricular (Purkinje Fibers): Fires at less than 40 bpm.

ECG Components

• P Wave: Atrial depolarization.
• PR Interval: 0.12-0.20 seconds (beginning of P to onset of QRS).
• QRS Complex: Ventricular depolarization, normal interval < 0.10 seconds.

Systematic Approach to Rhythm Analysis

• Rate: Determine fast vs slow.
• Rhythm: Regular vs irregular.
• P Waves: Presence and consistency.
• PR Interval: Consistency and duration.
• QRS Correlation: Check P to QRS relationship.

Common Arrhythmias

• Sinus Tachycardia: P wave before each QRS, rate > 100 bpm.
• Paroxysmal Supraventricular Tachycardia (PSVT): Rapid rate, P waves buried in T waves.
• Atrial Fibrillation (A-Fib): No distinct P waves, chaotic rhythm, potential for thrombi.
• Atrial Flutter: Sawtooth P waves, atrial rate 200-300 bpm, risk of thrombi.
• Ventricular Tachycardia (VT): Wide QRS, rate > 120 bpm, often pulseless.
• Ventricular Fibrillation (V-Fib): Chaotic, no effective cardiac output, cardiac arrest.
• Sinus Bradycardia: Rate < 60 bpm, regular rhythm.
• Junctional Rhythms: P wave may be abnormal or absent, rate 40-60 bpm.

AV Blocks

• First Degree Block: PR interval > 0.20 seconds, regular rhythm.
• Second Degree Block Type I (Wenckebach): Progressive PR lengthening until QRS drops.
• Second Degree Block Type II: Constant PR interval, but QRS may be dropped, prepare to pace.
• Third Degree Block: Complete block, dissociated atrial and ventricular rhythms, prepare for pacing.

Premature Beats

• PAC (Premature Atrial Contraction): Feels like a skipped beat.
• PVC (Premature Ventricular Contraction): Wide, bizarre QRS, can be multi-focal.

Pulseless Electrical Activity (PEA)

• Definition: Electrical activity without palpable pulse.
• Causes (6 Hs and 6 Ts): Hypovolemia, Hypoxia, Acidosis, Electrolyte imbalances, Hypothermia, Hypoglycemia; Tablets/Toxins, Tamponade, Tension Pneumothorax, Thrombosis (cardiac & pulmonary), Trauma.

Asystole

• No electrical activity, very poor prognosis, cardiac arrest scenario.

These notes summarize the key points on rhythm recognition as discussed in the lecture. Remember to apply a systematic approach for rhythm analysis and be aware of different arrhythmias and their characteristics.