Symptomatic myocardial bridges: overview of ischemic mechanisms and current diagnostic and treatment strategies

Abstract

This review article focuses on the morphological and functional alterations that characterize patients with myocardial bridges (MB) as well as the currently available diagnostic and treatment strategies. Because of incomplete understanding of the pathophysiology of MB, their clinical significance has been the subject of debate for the last quarter century. Investigational tools now available in the cardiac catheterization laboratory have helped clarify why symptoms and signs of ischemia can occur in such patients, especially when the only angiographic finding appears to be systolic compression or milking effect of a coronary vessel. Quantitative coronary angiography and intravascular ultrasound (IVUS) clearly demonstrate that the phasic systolic vessel compression visualized on the angiogram is coupled with a persistent diastolic diameter reduction. Intracoronary Doppler reveals increased flow velocities, retrograde systolic flow, and reduced coronary flow reserve. The clinical diagnosis can be established by significant percent lumen diameter and area narrowing, increased flow velocity, and by characteristic patterns such as the "half moon" phenomenon on IVUS and the early diastolic "finger tip" phenomenon on intracoronary Doppler. Successful medical, interventional, or surgical therapy leads not only to marked improvement or normalization of these alterations but also relief of angina and ischemia.

Myocardial bridges are free from atherosclerosis: Overview of the underlying mechanisms

“…Overall, the frequency of myocardial bridges in adults varies substantially, with higher prevalence (15% to 80%) reported in histopathology studies than in angiographic studies (0.5% to 2.5%) (1,3,4). The length of bridges varies from 4 mm to 40 mm, and the depth from 1 mm to 10 mm (1,3). Although bridges are usually clinically silent, some, such as the longer and deeper ones, manifest with myocardial ischemia, rhythm conduction disturbances, acute coronary syndromes or even sudden cardiac death (3).…”

“…The length of bridges varies from 4 mm to 40 mm, and the depth from 1 mm to 10 mm (1,3). Although bridges are usually clinically silent, some, such as the longer and deeper ones, manifest with myocardial ischemia, rhythm conduction disturbances, acute coronary syndromes or even sudden cardiac death (3). Usually, bridges are incidentally identified during diagnostic angiography or autopsy studies.…”

“…However, in some cases, the myocardial bridges lead to an acute coronary syndrome, possibly due to an exaggerated coronary constriction at systole, and subsequent intermittent flow cessation. In fact, myocardial bridging has been reported as a potential cause of acute myocardial infarction in the absence of atherothrombosis, especially in young, healthy individuals (3,29). Despite the ischemic aspect of bridges, their freedom from atherosclerosis constitutes an interesting observation that it is worth studying in animal models.…”

Increased TIMI frame count of coronary arteries in patients with myocardial bridging

“…Those signs and symptoms may develop due to either systolic compression of the coronary artery that can be detected on angiography or various hemodynamic abnormalities of coronary flow which can be documented on intracoronary Doppler assessment [1].…”

Ponte miocárdica multiarterial: apresentações clínica e anatômica incomuns

“…(2) Although ultrasound and intracoronary Doppler techniques have enhanced the knowledge of ischemia mechanisms, these have not yet been completely explained. (3) We intend to report the case of a myocardial bridge with uncommon clinical and anatomical presentations.…”