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AMCA ETC: Rhythm Recognition and Basic EKG Interpretation

AMCA ETC · Work through your exam, one topic at a time.

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Rhythm Recognition and Basic EKG Interpretation

Systematic interpretation prevents missed findings. Use a consistent sequence: rate, rhythm, P waves, PR interval, QRS width, and relationship between P and QRS.

Rate and rhythm

Count QRS complexes in a 6-second strip and multiply by 10 (or use the 300-150-100 method for regular rhythms). Normal sinus rhythm: 60–100 bpm, regular, upright P before every QRS, PR 0.12–0.20 s, QRS <0.12 s.

Key rhythms

  • Sinus bradycardia: <60 bpm, normal P-QRS. **Sinus tachycardia:** >100 bpm.
  • Atrial fibrillation: irregularly irregular, no distinct P waves, fibrillatory baseline.
  • Atrial flutter: sawtooth flutter waves, often 2:1 conduction.
  • SVT: fast, regular, narrow QRS, P waves often hidden.
  • PVC: wide, bizarre, premature, no preceding P, often followed by a compensatory pause.
  • Ventricular tachycardia: wide, regular, fast-treat as emergency.
  • Ventricular fibrillation: chaotic, no identifiable complexes-pulseless, start CPR.
  • Asystole: flat line-confirm leads, then CPR.
  • Heart blocks: first-degree = prolonged PR; second-degree type I = progressively lengthening PR; type II = dropped beats with constant PR; third-degree = no relationship between P and QRS.

Traps

Atrial fibrillation vs. multifocal atrial tachycardia (both irregular, but MAT has distinct P morphologies). PVC vs. aberrant conduction. Do not call artifact a rhythm.

Rule of thumb: Wide and fast = think ventricular until proven otherwise. Narrow and irregular = think atrial fibrillation.

Cardiac Testing, Monitoring, and Emergency Response

The technician supports multiple cardiac tests and is often the first to recognize a deterioration.

Testing modalities

  • Holter monitor: continuous recording over 24–48 hours for intermittent symptoms; teach the patient to log symptoms and activities.
  • Event monitor: worn longer, activated when symptoms occur.
  • Stress testing: records EKG during exercise; know that the technician prepares the patient, monitors vitals, and recognizes warning signs; stop testing for chest pain, severe dyspnea, or dangerous arrhythmias.
  • Telemetry monitoring: continuous observation; recognize alarm fatigue and verify leads before reacting.

Emergency response

Recognize the signs of a cardiac emergency: chest pain, diaphoresis, dyspnea, syncope, and a changing rhythm. For a pulseless patient, activate emergency response, start CPR, and retrieve the AED. Defibrillation is indicated for V-fib and pulseless V-tach; it is not for asystole or a pulseless electrical activity. Know the chain of survival: recognition, early CPR, rapid defibrillation, advanced care, post-resuscitation care.

Traps

Questions ask whether to defibrillate: shock V-fib and pulseless V-tach only. Another trap is the first action in an emergency-always patient safety and calling for help before documentation. Also know that a stress test is stopped for symptoms, not continued for "more data."

Worked example: A telemetry strip shows a chaotic, irregular waveform with no discernible QRS. You check the patient-unresponsive, no pulse. Action: call for help, start CPR, apply AED. You do not adjust leads first.

Rule of thumb: Shock V-fib and pulseless V-tach; never shock asystole.