microvascular dysfunction
Impaired function of small coronary arteries causing angina symptoms despite normal large vessel coronary arteries.
Full Definition
Microvascular dysfunction, also known as cardiac syndrome X, refers to abnormal function of the coronary microvasculature (vessels <500 micrometers in diameter) that results in impaired coronary flow reserve and myocardial ischemia. Patients typically present with chest pain and objective evidence of myocardial ischemia on stress testing, but have angiographically normal epicardial coronary arteries. The condition is more common in women and may be associated with endothelial dysfunction, increased coronary resistance, or abnormal pain perception. Diagnosis often requires specialized testing such as coronary flow reserve measurement or acetylcholine provocation.
Usage
Usage note: Often underdiagnosed condition; requires high index of suspicion in patients with typical angina but normal angiograms.
In Context
- "Despite normal coronary angiography, the patient's symptoms were attributed to microvascular dysfunction based on abnormal coronary flow reserve." — Cardiology consultation note
- "Women with chest pain and normal coronaries should be evaluated for microvascular dysfunction using specialized testing." — Clinical guideline