Understanding Sinus Rhythm

Introduction

Sinus rhythm refers to the normal rhythm of the heart that originates from the sinus node, the heart’s natural pacemaker. This means that each heartbeat is initiated by electrical impulses from the sinus node, ensuring a steady and coordinated contraction of the heart muscles.

How Does It Work?

The sinus node, located in the right atrium, generates electrical impulses at a normal rate of 60–100 beats per minute in a resting adult. These impulses travel through the atria, causing them to contract and push blood into the ventricles. Then, the signal reaches the atrioventricular (AV) node and spreads through the ventricles, ensuring an effective heartbeat.

Characteristics of Sinus Rhythm

A normal sinus rhythm has the following features: - The heart rate is within the normal range (60–100 bpm at rest). - Each P wave (representing atrial contraction) is followed by a QRS complex on an ECG. - The P waves have a consistent shape and appear before each QRS complex. - The RR intervals are regular, meaning the heart beats at a steady pace.

Why Is Sinus Rhythm Important?

A proper sinus rhythm ensures efficient blood circulation, delivering oxygen to all organs. Abnormal heart rhythms (arrhythmias) can lead to serious conditions such as dizziness, fainting, stroke, or even cardiac arrest.

When Is Sinus Rhythm Abnormal?

  • Sinus tachycardia (heart rate above 100 bpm) can be caused by stress, fever, anemia, or hyperthyroidism.
  • Sinus bradycardia (heart rate below 60 bpm) could be seen in athletes, during sleep, or due to heart disease.
  • Irregular sinus rhythm may result from breathing variations (sinus arrhythmia) or underlying heart conditions.

Conclusion

Maintaining a normal sinus rhythm is crucial for heart health. If you experience palpitations, dizziness, or chest pain, consult a doctor. An ECG is an effective tool to diagnose rhythm disturbances.


Source recommendations

1. American Heart Association Guidelines on Arrhythmias

  1. https://www.heart.org/en/health-topics/arrhythmia
  2. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001193
  3. https://www.heart.org/en/health-topics/arrhythmia/about-arrhythmia
  4. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000549
  5. https://pubmed.ncbi.nlm.nih.gov/29084733/

2. European Society of Cardiology Guidelines on Cardiac Electrophysiology

  1. https://www.escardio.org/
  2. https://pubmed.ncbi.nlm.nih.gov/11583910/
  3. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines
  4. https://academic.oup.com/eurheartj/article/34/29/2281/401445
  5. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Ventricular-Arrhythmias-and-the-Prevention-of-Sudden-Cardiac-Death

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