Sinus rhythm

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Phases of the sinus rhythm

Sinus rhythm describes the normofrequency, regular heartbeat of humans. It arises in the sinus node in the right atrium . The excitation of the heart and subsequently the myocardial contraction spreads from there first through the atria to the AV node and then on to the ventricles . Based on this anatomical position and electrophysiological stimulus transmission, the electrical heart axis must point to the bottom left , in contrast to the ectopic atrial rhythm. H. a positive P-wave can be seen in the limb lead II in addition to the normal criteria in the ECG for a rhythmic heart action.

Criteria in the EKG

  • Regular P waves
  • Normally configured P-waves with normal atrial vector
  • Constant PP intervals
  • Each P-wave is answered by a QRS complex


Depending on age and gender, a frequency of 60 to 100 beats per minute is considered normal. If the normal heartbeat becomes too slow (e.g. when sleeping), this is called sinus bradycardia , and if the heartbeat is too fast (e.g. during exertion) it is called sinus tachycardia . Irregular sinus rhythms, i.e. irregular beat sequences of the heart that proceed from irregular stimulation of the sinus node, are called sinus arrhythmia .
Pathological deviations in the development (irritation disorder ) or transmission of the cardiac excitation (conduction disorder ) are referred to as cardiac arrhythmias and, in the case of their origin in the sinus node, also summarized under the term sick sinus syndrome .

See also



  1. ^ Herbert Reindell , Helmut Klepzig: Diseases of the heart and the vessels. In: Ludwig Heilmeyer (ed.): Textbook of internal medicine. Springer-Verlag, Berlin / Göttingen / Heidelberg 1955; 2nd edition, ibid. 1961, pp. 450-598, here: p. 561 ( Die Sinusbradykardie ).