Understanding Different ECG Rhythms

Introduction

Electrocardiography (ECG) is a crucial tool for diagnosing heart conditions. It records the electrical activity of the heart and helps detect various heart rhythms. Understanding different ECG rhythms is essential for diagnosing arrhythmias, ischemia, and other cardiac conditions.

Normal Sinus Rhythm

• The normal heart rhythm originates in the sinoatrial (SA) node.
• It has a regular rate of 60-100 beats per minute (bpm).
• The P wave precedes each QRS complex, indicating proper atrial and ventricular conduction.

Common Abnormal Rhythms

1. Sinus Bradycardia

• A heart rate below 60 bpm.
• Can be normal in athletes but may indicate a problem if symptomatic (e.g., dizziness, fatigue).
• Causes: Medications (beta-blockers), hypothyroidism, sick sinus syndrome.

2. Sinus Tachycardia

• A heart rate above 100 bpm.
• Causes: Fever, anxiety, dehydration, anemia, heart failure.

3. Atrial Fibrillation (AFib)

• Irregularly irregular rhythm with no distinct P waves.
• Increases the risk of stroke.
• Requires anticoagulation therapy and rate/rhythm control.

4. Atrial Flutter

• Rapid, regular atrial contractions (saw-tooth appearance on ECG).
• May cause palpitations and dizziness.

5. Supraventricular Tachycardia (SVT)

• Rapid heart rate originating above the ventricles.
• Often occurs in younger patients and may require vagal maneuvers or medications for termination.

6. Ventricular Tachycardia (VT)

• Life-threatening rhythm originating in the ventricles.
• May lead to cardiac arrest if not treated promptly.
• Requires defibrillation in emergency situations.

7. Ventricular Fibrillation (VFib)

• Chaotic, disorganized electrical activity leading to no effective heartbeat.
• Immediate CPR and defibrillation are required.

8. Heart Blocks

• Delays or interruptions in electrical conduction between the atria and ventricles.
• Types:
  • First-degree AV block: Prolonged PR interval (>200 ms), usually benign.
  • Second-degree AV block:
    • Mobitz Type I (Wenckebach): Progressive PR interval prolongation before a dropped beat.
    • Mobitz Type II: Sudden dropped beats without PR prolongation, more serious.
  • Third-degree AV block: Complete dissociation between P waves and QRS complexes, requiring a pacemaker.

Conclusion

ECG is a valuable diagnostic tool for identifying different heart rhythms. Early detection and proper management of arrhythmias can prevent complications like stroke or sudden cardiac arrest. If you have concerns about your ECG or heart rhythm, consult a cardiologist.

Source recommendations

1. American Heart Association Guidelines for ECG Interpretation

1. https://www.heart.org/en/health-topics/heart-attack/diagnosing-a-heart-attack/electrocardiogram-ecg-or-ekg
2. https://www.ahajournals.org/doi/10.1161/circulationaha.108.191095
3. https://www.heart.org/-/media/files/affiliates/mwa/kansas-city/kc-cardiac-and-stroke-symposium/2020-event-documents/cardiac-presentations/2-ecg-hockstad.pdf?la=en
4. https://www.ahajournals.org/doi/10.1161/circulationaha.108.191098
5. https://pubmed.ncbi.nlm.nih.gov/19281932/

2. European Society of Cardiology Guidelines on Cardiac Arrhythmias

1. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Ventricular-Arrhythmias-and-the-Prevention-of-Sudden-Cardiac-Death
2. https://academic.oup.com/eurheartj/article/43/40/3997/6675633
3. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Supraventricular-Tachycardia
4. https://pubmed.ncbi.nlm.nih.gov/36017572/
5. https://www.ahajournals.org/doi/10.1161/01.cir.0000091380.04100.84