Definition of Rhythm, sinus
Rhythm, sinus: The normal regular rhythm of the heart set by the natural pacemaker of the heart called the sinoatrial (or sinus) node. It is located in the wall of the right atrium (the right upper chamber of the heart). Normal cardiac impulses start there and are transmitted to the atria and down to the ventricles (the lower chambers of the heart).
Sinus arrhythmia refers to the normal increase in heart rate that occurs during inspiration (when you breathe in). This is a normal response and is more accentuated in children than adults.
Sinus tachycardia refers to a fast heartbeat (tachycardia) because of rapid firing of the sinoatrial (sinus) node. This occurs in response to exercise, exertion, excitement, pain, fever, excessive thyroid hormone, low blood oxygen (hypoxia), stimulant drugs (such as caffeine), etc.
The lack of normal sinus rhythm is an arrhythmia, an abnormal heart rhythm.
Last Editorial Review: 6/14/2012
Back to MedTerms online medical dictionary A-Z List
Need help identifying pills and medications?
- Allergic Skin Disorders
- Bacterial Skin Diseases
- Bites and Infestations
- Diseases of Pigment
- Fungal Skin Diseases
- Medical Anatomy and Illustrations
- Noncancerous, Precancerous & Cancerous Tumors
- Oral Health Conditions
- Papules, Scales, Plaques and Eruptions
- Scalp, Hair and Nails
- Sexually Transmitted Diseases (STDs)
- Vascular, Lymphatic and Systemic Conditions
- Viral Skin Diseases
- Additional Skin Conditions