Sinoatrial node

Looks like

A small strip of specialised heart muscle, about 1–2 cm long, in the wall of the right atrium where the superior vena cava enters.

What it does

The heart's natural pacemaker: fires by itself and sets the rate of every beat.

Keeping it well

It slows with age and with some drugs such as beta-blockers; a pulse that stays very slow with dizziness or fainting is 'sick sinus syndrome' and is fixed with a pacemaker.

Related conditions

• 22q11.2 deletion syndrome (DiGeorge)
• Amyloidosis (AL and ATTR)
• Aortic stenosis
• Atrial fibrillation
• Atrial flutter
• Botulism
• Brugada syndrome
• Cardiomyopathy (dilated, restrictive, arrhythmogenic)
• Chagas disease
• Chickenpox (varicella)
• Chronic neuropathic pain
• Chronic pain syndrome
• Congenital heart defects
• Coronary artery disease
• Diphtheria
• Down syndrome (trisomy 21)
• Eating disorders
• Extra heartbeats (ectopics and palpitations)
• Fainting (syncope)
• Fibromyalgia
• Friedreich's ataxia
• Guillain-Barré syndrome
• Heart block & bradycardia
• Heart failure
• Hypertrophic cardiomyopathy
• Hypothermia & frostbite
• Kawasaki disease
• Long QT syndrome
• Lyme disease
• Myasthenia gravis
• Myocarditis
• Orthostatic hypotension & POTS
• Panic disorder
• Pericardial effusion & tamponade
• Pericarditis
• Peripheral neuropathy
• Rabies
• Restless legs syndrome
• Shingles (herpes zoster)
• Shock (circulatory failure)
• Sudden cardiac arrest
• Sudden infant death syndrome
• Supraventricular tachycardia
• Takotsubo (stress) cardiomyopathy
• Tetanus
• Tuberous sclerosis complex
• Ventricular tachycardia
• Vitamin B1, C and other deficiencies
• Wolff–Parkinson–White syndrome