The influence of hyperthyroidism on pharmacologically induced contractions of isolated resistance arteries

A Rare Encounter: Unstable Vasospastic Angina Induced by Thyrotoxicosis

Coronary artery vasospasm plays a crucial role in the prevalence of unstable angina. Despite common misdiagnosis, there is limited evidence on this topic. Here, we present a rare case of unstable vasospastic angina in a female with severe thyrotoxicosis. Case Report: A 62-year-old female patient was admitted to the cardiac intensive care unit due to crushing chest pain at rest. The patient exhibited ischemic changes on the ECG with a normal troponin I level. Recurrent chest pain prompted urgent coronary angiography, revealing generalized vasospasm of all coronary artery branches including the left main coronary artery. Intracoronary nitroglycerin injection partially alleviated the vasospasm; however, there was a persistent stenosis in the left main artery. Subsequent intravascular ultrasound demonstrated an anatomically normal left main artery. Post-procedure, laboratory tests revealed undetectable levels of thyroid-stimulating hormone and thyroid hormones above the detectable level. The patient was initiated on methimazole and discharged symptom-free, expecting a good prognosis under conservative management. Conclusions: Clinically significant coronary vasospasm triggered by thyrotoxicosis remains a rarity in clinical practice, often posing diagnostic challenges. This case emphasizes the significance of intracoronary nitroglycerin and intravascular ultrasound in discerning the etiology of coronary lesions seen on angiography. We advocate for these techniques to optimize invasive coronary artery diagnostics, enabling the selection of the appropriate treatment strategies and improving long-term prognosis.

Serotonin and blood pressure regulation

5-Hydroxytryptamine (5-HT; serotonin) was discovered more than 60 years ago as a substance isolated from blood. The neural effects of 5-HT have been well investigated and understood, thanks in part to the pharmacological tools available to dissect the serotonergic system and the development of the frequently prescribed selective serotonin-reuptake inhibitors. By contrast, our understanding of the role of 5-HT in the control and modification of blood pressure pales in comparison. Here we focus on the role of 5-HT in systemic blood pressure control. This review provides an in-depth study of the function and pharmacology of 5-HT in those tissues that can modify blood pressure (blood, vasculature, heart, adrenal gland, kidney, brain), with a focus on the autonomic nervous system that includes mechanisms of action and pharmacology of 5-HT within each system. We compare the change in blood pressure produced in different species by short- and long-term administration of 5-HT or selective serotonin receptor agonists. To further our understanding of the mechanisms through which 5-HT modifies blood pressure, we also describe the blood pressure effects of commonly used drugs that modify the actions of 5-HT. The pharmacology and physiological actions of 5-HT in modifying blood pressure are important, given its involvement in circulatory shock, orthostatic hypotension, serotonin syndrome and hypertension.

Thyrotoxicosis with coronary spasm that required coronary artery bypass surgery

We describe a 47-year-old woman with severe coronary vasospasm induced by hyperthyroidism. The patient complained of anginal chest pain without specific characteristics of thyrotoxicosis. Coronary arteriography was performed and revealed 90% stenosis of both the left and right coronary os. She was treated with emergent coronary artery bypass graft surgery. Postoperatively, she exhibited a comatose mentality. Severe thyrotoxicosis was indicated on thyroid function tests and thyrotoxic storm was diagnosed. Nineteen days after the surgery and following the initiation of propylthiouracil treatment, coronary arteriography revealed entirely normal coronary arteries.

Severe coronary artery spasm can be associated with hyperthyroidism

BACKGROUND

Coronary artery spasm is not infrequently seen in Korea. Most of the patients with coronary spasm show a focal spasm in coronary angiography. However, the cause of the disease is not well known. There have been a few anecdotal case reports of coronary artery spasm associated with hyperthyroidism, but there has not been a report concerning a large series of such patients. Over a period of 5 years and 8 months, we experienced eight patients having the diffuse or severe type of coronary artery spasm in association with hyperthyroidism.

METHODS

We investigated the characteristics of the patients with coronary artery spasm, which was diagnosed by coronary angiography or by provocation with an intracoronary injection of acetylcholine or ergonovine. The demographic data, coronary angiographic findings, thyroid function test results, and the follow-up clinical data of the eight patients having coronary artery spasm associated with hyperthyroidism were analyzed.

RESULTS

All eight patients had Graves' disease. In six patients, the coronary arterial vasoconstriction developed during the coronary angiography without an injection of ergonovine. In three patients, the left main stem coronary artery was involved in the spasm. Among these eight patients, five were female, and all of these female patients were < or = 51 years old. All of the patients were treated with anti-thyroid medications, calcium channel blockers, and long-acting nitroglycerines; they all remained free of chest pain during the median follow-up period of 5 years.

CONCLUSIONS

A severe form of coronary artery spasm could be associated with hyperthyroidism. A high level of suspicion and the thyroid function study should be mandatory for patients with coronary artery spasm, especially for the young female patients.