Smooth Muscle Hypercontractility
At a cellular level, pathways that lead to enhanced myosin light chain phosphorylation promote vasoconstriction. Increased activity of Rho-kinase leading to enhanced myosin light chain phosphorylation has been implicated in the pathogenesis of coronary vasospasm. Diagnosis
There are no set criteria to diagnose coronary vasospasm. Thorough history taking by a clinician can assist in the diagnosis of coronary vasospasm. In cases where symptoms of chest pain are present, identifying features that distinguish episodes of vasospastic angina from traditional angina can aid in the diagnosis. Features such as chest pain at rest, a diurnal variation in tolerance for exercise with a reduction in tolerance for exercise in the morning, and responsiveness of chest pain to calcium channel blockers as opposed to beta blockers can be important clues.EKG can occasionally be used to diagnose episodes of coronary vasospasm. However, relying on EKG is not always possible due to the transient nature of coronary vasospasm episodes. Due to the challenge of capturing episodes of coronary vasospasm spontaneously, provocative testing to induce coronary vasospasm during coronary catheterization can be used to make the diagnosis. Provocative testing relies upon the use of pharmacological agents that promote or trigger episodes of vasospasm. Agents commonly administered include ergonovine and acetylcholine. Both pharmacological agents have vasoconstrictive effects on coronary arteries. However, in the clinical setting, provocative testing is not routinely performed. The reason for this is due to the adverse effects of these pharmacological agents.
EKG findings
When coronary vasospasm causes an artery to undergo complete occlusion, an EKG might show evidence of ST-segment elevation in the leads indicative of that arterys territory. Transient ST-segment depression can also occur, usually in the setting of sub-total occlusion of an artery.Additional EKG findings in coronary vasospasm include evidence of arrhythmias that might be induced by ischemia: ventricular premature contractions, ventricular tachycardia, ventricular fibrillation, and more. History
Chest pain due to coronary vasospasm was described in the medical literature by Prinzmetal et al. in 1959. This discovery led to this type of angina being referred to in the literature as Prinzmetal angina. A following study further distinguished this angina from classical angina pectoris due to the fact that the results showed that the patients with chest pain due to coronary vasospasm lacked evidence of atherosclerosis on cardiac catheterization. Angina due to coronary vasospasm is also known as variant angina. References
Further reading


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