Myocardial vessel vasospasm Myocardial vessel vasospasm, also known as coronary artery vasospasm or variant angina, is a condition characterized by sudden, temporary narrowing or constriction of the coronary arteries, which supply blood to the heart muscle (myocardium). This transient narrowing restricts blood flow to the heart, leading to chest pain or angina. Etiology and Pathophysiology The exact cause of myocardial vessel vasospasm is not fully understood, but several factors contribute to its development:    Smooth muscle dysfunction: Abnormal function of the smooth muscle cells in the arterial walls, which regulate vascular tone and diameter. Endothelial dysfunction: Impaired function of the endothelial cells lining the blood vessels, leading to abnormal responses to various stimuli. Autonomic nervous system: Dysregulation of the autonomic nervous system, which controls blood vessel tone and can trigger vasospasm.  Hypersensitivity to vasoconstrictors: Increased sensitivity of coronary arteries to vasoconstrictive substances such as serotonin, histamine, or endothelin. Clinical Features Myocardial vessel vasospasm typically presents with episodes of chest pain or discomfort, often described as angina. Key clinical features include:     Episodic nature: Chest pain episodes occur spontaneously and often at rest, typically during early morning hours or periods of emotional stress. Duration: Episodes of angina due to vasospasm are usually brief, lasting from a few seconds to several minutes. Response to nitroglycerin: Unlike typical angina, which is relieved by rest or nitroglycerin, vasospastic angina may initially worsen with nitroglycerin before improving. Variability: The frequency and severity of episodes can vary widely between individuals, ranging from occasional mild episodes to frequent and severe attacks. Diagnostic Evaluation Diagnosing myocardial vessel vasospasm involves a combination of clinical evaluation, diagnostic tests, and exclusion of other causes of chest pain. Key diagnostic approaches include:    Electrocardiogram (ECG): ECG during episodes of chest pain may show transient ST-segment elevation, which resolves spontaneously. Coronary angiography: Typically performed during an episode of chest pain to visualize coronary arteries. Angiography may show transient narrowing of coronary arteries, but often arteries appear normal between episodes. Provocative testing: Ergonovine or acetylcholine provocation tests may be used to induce coronary artery spasm during cardiac catheterization, confirming the diagnosis. Management and Treatment Management of myocardial vessel vasospasm aims to relieve symptoms, prevent complications, and reduce the frequency of episodes. Treatment strategies include:    Calcium channel blockers: First-line medications such as verapamil or diltiazem are effective in preventing coronary artery spasm by relaxing smooth muscle cells. Nitroglycerin: Sublingual nitroglycerin is used to relieve acute episodes of chest pain by dilating coronary arteries and improving blood flow. Long-acting nitrates: Nitroglycerin patches or long-acting oral nitrates may be prescribed to prevent recurrent episodes.