Heart Rhythm is a peer-reviewed medical journal that covers the study and management of cardiac arrhythmia. It is the official journal of the Heart Rhythm Society and the Cardiac Electrophysiology Society. Its major focus is research and therapy of heart rhythm disorders, including mechanisms and electrophysiology, clinical and experimental, genetics, ablation, devices, drugs, and surgery. Other sections include contemporary and historical reviews, unique case reports, viewpoints, cell to bedside, hands on, featured arrhythmias, images with videos viewable on the internet, pacing/icd problems, creative concepts, humanism in medicine, EP news, editorial commentaries, basic/clinical implications, historical vignettes, current controversies, and ten questions for allied professionals.

Sinus rhythm refers to any cardiac rhythm where depolarisation of the cardiac muscle begins at the sinus node. It is characterised by the presence of correctly-oriented P waves on the  electrocardiogram (ECG). Sinus rhythm is necessary, but not sufficient, for normal electrical activity within the heart.