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Silent Myocardial Ischemia: What Are the Hidden Dangers of Coronary Spasm?
Coronary artery spasm is a sudden, temporary blockage of a coronary artery, either partially or completely. In 1959, Prinzmetal et al. first described a type of chest pain caused by coronary artery spasm, which they called variant angina. Subsequent studies have shown that this type of angina is different from traditional angina, which usually shows atherosclerotic plaques during cardiac catheterization, while the coronary arteries of these patients appear normal. When coronary artery spasm occurs, temporary blockage causes ischemia, which may cause a variety of symptoms, ranging from asymptomatic myocardial ischemia to myocardial infarction and sudden cardiac death.
Symptoms and symptoms
Coronary artery spasm typically causes chest pain at rest, also known as variant angina. This chest pain is often more common during certain times, especially late at night and into the early morning. These episodes may be accompanied by symptoms of nausea, vomiting, cold sweats, and even fainting. In addition to chest pain, symptoms of fatigue, shortness of breath, and palpitations may also occur. In some cases, coronary artery spasm may even occur without any obvious symptoms, resulting in asymptomatic or painless myocardial ischemia.
Complications
Depending on how long the blockage lasts, different syndromes of myocardial ischemia may occur. Transient obstruction can result in silent myocardial ischemia, which may also be accompanied by arrhythmias. Longer occlusion times increase the risk of stable or unstable angina, myocardial infarction, and sudden cardiac death.
Risk Factors
Unlike traditional angina, coronary artery spasm is not significantly affected by common cardiovascular risk factors. Only smoking is considered a modifiable risk factor and is known to be associated with variant angina. There are many factors that may trigger coronary artery spasm, some of which work by affecting the autonomic nervous system. For example, stress, high-intensity exercise, cold weather, and psychological stress can increase the activity of the sympathetic nervous system, thereby triggering vascular spasm. shrink.
PathophysiologyAlthough the exact pathophysiology of coronary artery spasm has not been fully elucidated, multiple factors are thought to contribute to the reactive cardiac arterial abnormalities. During this process, spasm may occur when a certain area of the artery overreacts to the vasoconstrictive stimulus. When a coronary artery spasms, the myocardial tissue will become ischemic due to the blockage in blood flow, causing corresponding symptoms. Some factors that may contribute to coronary artery spasm include:
Endothelial dysfunction: In some cases, endothelial effects on blood flow regulation may lead to coronary artery spasm.
Chronic inflammation: Chronic inflammation associated with smoking is thought to impair endothelial cell function.
Diagnosis
There are no clear diagnostic criteria for coronary artery spasm. A thorough medical history collected by a physician can assist in the diagnosis, especially when chest pain symptoms are present. It is important to distinguish the different characteristics of variant angina from traditional angina. An electrocardiogram (ECG) is sometimes used to diagnose coronary artery spasm, but because of its transient nature, ECG alone is not always a viable option. Because of the difficulty in capturing coronary artery spasm, provocative testing is often used to induce coronary artery spasm during cardiac catheterization.
Provocation testing relies on drugs that stimulate the coronary arteries, such as ergotamine and acetylcholine, which can trigger spasms.
ECG Results
When a coronary artery spasm causes complete blockage of an artery, an EKG may show ST segment elevation in the area supplied by that artery. In contrast, a temporary depression of the ST segment is usually seen in cases of partial obstruction. Coronary artery spasm may also cause ECG changes including arrhythmias caused by ischemia.
History Review
In medical literature, chest pain due to coronary artery spasm was first described by Prinzmetal in 1959. This discovery led to this type of angina being called Prinzmetal's angina, and subsequent studies further indicated that this type of angina was not related to atherosclerosis. In the 1970s and 1980s, research by Dr. Robert A. Chahine provided insights into the role of coronary artery spasm in Prinzmetal's angina, leading to its effective identification and treatment.
The insidious nature of coronary artery spasm makes it an important topic in cardiovascular disease management. In the face of these potential risk factors, should we pay more attention to early detection and health prevention measures to reduce the incidence of coronary artery spasm?
