ECG Rhythm Types

Introduction

Electrocardiography (ECG) is a crucial tool in cardiology used to assess the heart’s electrical activity. The ECG tracing provides information on different heart rhythms, which can be classified into normal and abnormal (arrhythmic) patterns. Understanding these rhythm types is essential for diagnosing and managing various cardiovascular conditions.

Normal Sinus Rhythm (NSR)

This is the normal rhythm of a healthy heart, originating from the sinoatrial (SA) node. Key characteristics: - Regular rhythm - Heart rate between 60-100 beats per minute (bpm) - Normal P wave before every QRS complex - Normal PR and QT intervals

Sinus Arrhythmias

• Sinus Bradycardia: Heart rate < 60 bpm, can be normal in athletes or occur due to vagal stimulation.
• Sinus Tachycardia: Heart rate > 100 bpm, common with exercise, stress, or fever.
• Sinus Arrest/Pause: The SA node temporarily stops firing, causing a delay in the next heartbeat.

Atrial Rhythms

• Atrial Fibrillation (AFib): Irregular, rapid rhythm with no distinct P waves.
• Atrial Flutter: Regular but rapid atrial activity, often with a characteristic “sawtooth” pattern.
• Supraventricular Tachycardia (SVT): Rapid heart rhythm originating above the ventricles, often sudden onset and termination.

Ventricular Rhythms

• Ventricular Tachycardia (VT): A fast, wide-QRS rhythm originating in the ventricles, potentially life-threatening.
• Ventricular Fibrillation (VFib): Disorganised electrical activity leading to cardiac arrest if untreated.
• Premature Ventricular Contractions (PVCs): Extra, abnormal beats originating in the ventricles.

Heart Blocks (Conduction Abnormalities)

• First-Degree AV Block: Prolonged PR interval but regular conduction.
• Second-Degree AV Block:
  • Mobitz Type I (Wenckebach): Progressive PR prolongation until a beat is dropped.
  • Mobitz Type II: Sudden, unpredictable dropped beats without progressive PR prolongation.
• Third-Degree AV Block (Complete Heart Block): No electrical communication between atria and ventricles, requiring a pacemaker.

Conclusion

Recognizing different ECG rhythms is essential for early diagnosis and treatment of cardiac conditions. If you experience symptoms like palpitations, dizziness, or fainting, seek medical attention immediately.

Source recommendations

1. American Heart Association Guidelines on 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 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