Sinus rhythm (a.k.a. normal sinus rhythm) refers to the normal heart beat originating from the sinoatrial node. This is manifested as an upright P wave in lead II of the ECG. Sinus bradycardia ...

Severe sinus bradycardia Sinus pauses/sinus arrest Sinoatrial nodal exit block Chronotropic incompetence (failure of heart rate to increase during exercise) Clinical symptoms depend on the mechanism.

That troublesome headache might not be a migraine or brought on by tension. It could be caused by sinus trouble, said doctors at Baylor College of Medicine. “Our sinuses are air-filled spaces in our ...