Myocardial Bridge and Atherosclerosis, an Intimal Relationship.

PURPOSE OF REVIEW: This review investigates the relationship between myocardial bridges (MBs), intimal thickening in coronary arteries, and Atherosclerotic cardiovascular disease. It focuses on the role of mechanical forces, such as circumferential strain, in arterial wall remodeling and aims to clarify how MBs affect coronary artery pathology. REVIEW FINDINGS: MBs have been identified as influential in modulating coronary artery intimal thickness, demonstrating a protective effect against thickening within the MB segment and an increase in thickness proximal to the MB. This is attributed to changes in mechanical stress and hemodynamics. Research involving arterial hypertension models and vein graft disease has underscored the importance of circumferential strain in vascular remodeling and intimal hyperplasia. Understanding the complex dynamics between MBs, mechanical strain, and vascular remodeling is crucial for advancing our knowledge of coronary artery disease mechanisms. This could lead to improved management strategies for cardiovascular diseases, highlighting the need for further research into MB-related vascular changes.

Association of Coronary Computed Tomography-Defined Myocardial Bridge With Pre- and Post-Procedural Fractional Flow Reserve in Patients Undergoing Elective Percutaneous Coronary Intervention.

BACKGROUND: Myocardial bridge (MB) is a common coronary anomaly characterized by a tunneled course through the myocardium. Coronary computed tomography angiography (CCTA) can identify MB. The impact of MB detected by CCTA on coronary physiological parameters before and after percutaneous coronary intervention (PCI) is unknown. METHODS AND RESULTS: We investigated 141 consecutive patients who underwent pre-PCI CCTA and fractional flow reserve (FFR)-guided elective PCI for de novo single proximal lesions in the left anterior descending artery (LAD). We compared clinical demographics and physiological parameters between patients with and without CCTA-defined MB. MB was identified in 46 (32.6%) patients using pre-PCI CCTA. The prevalence of diabetes was higher among patients with MB. Median post-PCI FFR values were significantly lower among patients with than without MB (0.82 [interquartile range 0.79-0.85] vs. 0.85 [interquartile range 0.82-0.89]; P=0.003), whereas pre-PCI FFR values were similar between the 2 groups. Multivariable linear regression analysis revealed that the presence of MB and greater left ventricular mass volume in the LAD territory were independently associated with lower post-PCI FFR values. Multivariable logistic regression analysis also revealed that the presence of MB and lower pre-PCI FFR values were independent predictors of post-PCI FFR values ≤0.80. CONCLUSIONS: CCTA-defined MB independently predicted both lower post-PCI FFR as a continuous variable and ischemic FFR as a categorical variable in patients undergoing elective PCI for LAD.

A framework of myocardial bridge detection with x-ray angiography sequence.

BACKGROUND: Myocardial bridges are congenital anatomical abnormalities in which myocardium covers a segment of coronary arteries, leading to stenocardia, myocardial ischemia, and sudden cardiac death in severe cases. However, automatic diagnosis of myocardial bridge presents significant challenges. METHOD: A novel framework of myocardial bridge detection with x-ray angiography sequence is proposed, which can realize automatic detection of vessel stenosis and myocardial bridge. Firstly, we employ a novel neural network model for coronary vessel segmentation, which consists of both CNNs and transformer structures to effectively extract both local and global information of the vessels. Secondly, we describe the vessel segment information, establish the vessel tree in the image, and fuse the vessel tree information between sequences. Finally, based on vessel stenosis detection, we realize automatic detection of the myocardial bridge by querying the blood vessels between the image sequence information. RESULTS: In experiment, we evaluate the segmentation results using two metrics, Dice and ASD, and achieve scores of 0.917 and 1.39, respectively. In the stenosis detection, we achieve an average accuracy rate of 92.7% in stenosis detection among 262 stenoses. In multi-frame image processing, vessels in different frames can be well-matched, and the accuracy of myocardial bridge detection achieves 75%. CONCLUSIONS: Our experimental results demonstrate that the algorithm can automatically detect stenosis and myocardial bridge, providing a new idea for subsequent automatic diagnosis of coronary vessels.

Prognostic impact of nitrate therapy in patients with myocardial bridge and coexisting coronary artery spasm.

The aim of this study was to investigate the prognostic impact of nitrate therapy in patients with myocardial bridge (MB) and coexisting coronary artery spasm (CAS). MB often accompanies CAS. Nitrates have been widely used as anti-ischemic drugs in CAS patients, while it is not recommended in MB patients. Thus, we investigated the long-term impact of nitrate on clinical outcomes in patients with both CAS and MB. A retrospective observational study was performed using propensity score matching (PSM) in a total of 757 consecutive MB patients with positive acetylcholine (Ach) provocation test. Patients were divided into two groups according to the regular administration of nitrates (nitrate group: n = 504, No nitrate group; n = 253). The PSM was used to adjust for selection bias and potential confounding factors, and major clinical outcomes were compared between the two groups up to 5 years. Baseline characteristics were well-matched between the two groups following PSM (n = 211 for both groups). There was no significant difference in the incidence of death, myocardial infarction, and major adverse cardiovascular events (MACEs) between the two groups. However, the nitrate group showed a significantly higher rate of recurrent angina which subsequently needed re-evaluation of coronary arteries by follow-up angiography (15.7 vs. 5.7%, Log-rank p = 0.012) compared to the non-nitrate group. Long-term nitrate administration in patients with MB and coexisting CAS did not show benefit in reducing MACE, rather it was associated with a higher incidence of recurrent angina requiring follow-up angiography.

Impact of myocardial bridge on non-culprit vessel lumen changes in patients with acute coronary syndrome.

This study aims to clarify the impact of myocardial bridge (MB) on the presence and progression of atherosclerosis in left descending coronary artery (LAD) in patients with acute coronary syndrome (ACS). Ninety-eight patients who underwent percutaneous coronary intervention with the diagnosis of ACS and follow-up coronary angiography but had no significant stenosis in the LAD were included. MB was defined based on coronary angiography. Quantitative coronary angiography was performed to determine the segments where MB was present and proximal to the MB (proximal segment) in patients with MB. In patients without MB, a corresponding region was quantitatively analyzed. The primary endpoint was changes in minimum lumen diameter (MLD) and percentage of diameter stenosis (%DS) in the proximal segment from baseline to follow-up angiography, namely ΔMLD and Δ%DS. MB was identified in 29 (29.6%) patients. Patients with MB had larger MLD and smaller %DS in the proximal segment than their counterpart. During the mean follow-up period of 12.9 ± 5.7 months, MLD and %DS in the proximal segment did not change significantly from baseline to follow-up in patients with and without MB. No significant between-group differences were observed in ΔMLD and Δ%DS. Baseline MLD was identified as the only factor associated with ΔMLD in the proximal segment. ACS patients who had MB but no significant stenosis in the LAD had larger MLD and smaller %DS at the segment proximal to MB compared to those without. In this selected population, serial lumen changes assessed by ΔMLD were not associated with the presence of MB in the LAD.

Myocardial bridge in a patient with castration-resistant metastatic prostate cancer treated with enzalutamide.

INTRODUCTION: Myocardial bridge is a morphological anomaly of the heart characterised by the presence of a myocardial segment above a coronary artery, which results in a higher risk of cardiovascular events. In patients with prostate cancer treated with androgen receptor-targeted agents, a higher risk of cardiotoxicity was observed. CASE REPORT: An 88 years old man with metastatic castration-resistant prostate cancer in treatment with enzalutamide, denosumab, and triptorelin presented to our attention complaining dyspnoea and angina pectoris. MANAGEMENT AND OUTCOME: Blood examinations revealed normal Troponin I levels. Transthoracic echocardiography revealed no signs of acute myocardial ischaemia. The treadmill stress test revealed S-T tract under levelling in V4-V6 with a very slow resolution. Coronary angiography identified a myocardial bridge in the medium tract of the interventricular anterior artery. Due to these findings, ranolazine and simvastatin were started and, after multidisciplinary assessment, we decided to continue the treatment with enzalutamide. At the first follow-up visit echocardiography found out the cardiological reports stability and no therapy changes were performed. During follow-up visit cardiological revaluation showed reports stability and no therapy changes were performed. DISCUSSION: Due to the high prevalence of prostate cancer in elderly patients at high cardiovascular risk and the increasing use of androgen receptor-targeted agent, a multidisciplinary approach is highly recommended to weigh survival benefits on toxicities. This case report may support the use of androgen receptor-targeted agent in elderly patients with controlled cardiovascular diseases, a population that is often excluded from randomised trials.

Myocardial bridge in a child with cardiac arrest and ventricular fibrillation: a bridge over troubled water?

Resuscitated cardiac arrest in a child triggers a comprehensive workup to identify an aetiology and direct management. The presence of a myocardial bridge does not automatically imply causation. Careful determination of the haemodynamic significance of the myocardial bridge is critical to avoid an unnecessary sternotomy and to provide appropriate treatment.

Influence of myocardial bridge on atherosclerotic plaque distribution and characteristics evaluated by near-infrared spectroscopy intravascular ultrasound.

BACKGROUND: This study aims to clarify whether myocardial bridge (MB) could influence atherosclerotic plaque characteristics assessed using near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) imaging. METHODS: One hundred and sixteen patients who underwent percutaneous coronary intervention (PCI) using NIRS-IVUS imaging were included. MB was defined as an echo-lucent band surrounding left anterior descending artery (LAD). In MB patients, LAD was divided into three segments: proximal, MB, and distal segments. In non-MB patients, corresponding three segments were defined based on the average length of the above segments. Segmental maximum plaque burden and lipid content derived from NIRS-IVUS imaging in the section of maximum plaque burden were evaluated in each segment. Lipid content of atherosclerotic plaque was evaluated as lipid core burden index (LCBI) and maxLCBI4mm. LCBI is the fraction of pixels indicating lipid within a region multiplied by 1000, and the maximum LCBI in any 4-mm region was defined as maxLCBI4mm. RESULTS: MB was identified in 42 patients. MB was not associated with maximum plaque burden in proximal segment. LCBI and maxLCBI4mm were significantly lower in patients with MB than those without in proximal segment. Multivariable analysis demonstrated both MB and maximum plaque burden in proximal segment to be independent predictors of LCBI in proximal segment. CONCLUSIONS: Lipid content of atherosclerotic plaque assessed by NIRS-IVUS imaging was significantly smaller in patients with MB than those without. MB could be considered as a predictor of lipid content of atherosclerotic plaque when assessed by NIRS-IVUS imaging.

Myocardial Bridge or Something Else?

In this E-Challenge, the authors report on a patient with symptoms of exertional dyspnea and angina, scheduled to have surgical unroofing of an identified myocardial bridge (MB). An MB is very common in patients with hypertrophic cardiomyopathy (HCM). Intraoperative transesophageal echocardiography with provocative maneuvers revealed the patient had a systolic anterior motion of the mitral valve with septal contact and resulting outflow tract obstruction despite the notable absence of significant basal septal hypertrophy. HCM has many phenotypic variants that can make the identification of patients with latent left ventricular outflow tract obstruction difficult in the absence of a high index of suspicion. In this report, the authors discuss the association between MBs and HCM and the importance of recognizing phenotypic variants of HCM.

Myocardial bridge evaluation towards personalized medicine: study design and preliminary results of the RIALTO registry.

Myocardial bridge (MB) is the most frequent inborn coronary artery variant in which a portion of the myocardium overlies an epicardial coronary artery segment. Although MB has long been considered a benign entity, a growing body of evidence has suggested its association with angina and adverse cardiac events. However, to date, no data on long-term prognosis are available, nor on therapies improving cardiovascular outcomes. We are currently conducting an ambispective, observational, multicentre, study in which we enrol patients with a clinical indication to undergo coronary angiography (CA) and evidence of MB, aiming to describe the incidence of symptoms and cardiovascular events at baseline and at long-term follow-up (FUP). The role of invasive full-physiology assessment in modifying the discharge therapy and eventually the perceived quality of life and the incidence of major cardiovascular events will be analysed. Basal clinical-instrumental data of eligible and consenting patients have been acquired after CA; FUP was performed 6, 12, and 24 months after the angiographic diagnosis of MB. The primary endpoint of the study is the incidence of major adverse cardiovascular events (MACE), defined as the composite of cardiac death, myocardial infarction, cardiac hospitalization, and target vessel revascularization; the secondary endpoints are the rate of patients with Seattle Angina Questionnaire (SAQ) summary score <70 and the incidence of MACE in patients undergoing invasive intracoronary assessment. Among patients undergone FUP visits, we recorded 31 MACE at 6 months (11.6%), 16 MACE at 12 months (6.5%), and 26 MACE at 24 months (13.5%). The rate of patients with SAQ <70 is 18.8% at 6 months, 20.6% at 12 months, and 21.8% at 24 months. To evaluate the prognostic role of invasive intracoronary assessment, we compared MB patients who underwent only angiographic evaluation (Angio group) to those who underwent acetylcholine (ACH) provocative test with indication to calcium-channel blockers (CCBs) at discharge (Angio + ACH + CCBs group) and those who underwent functional assessment with fractional flow reserve (FFR) with indication to beta-blockers (BBs) at discharge (Angio + FFR + BBs group). After 2 years of FUP, the rate of MACE was significantly reduced in both Angio + ACH + CCBs group (6 vs. 25%, P = 0.029) and Angio + FFR + BBs group (3 vs. 25%, P = 0.005) compared with Angio group. The preliminary results of our study showed that MB may be a cause of angina and adverse cardiac events in patients referred to CA for suspected coronary artery disease (CAD). Full-physiology assessment unmasking MB-related ischaemia mechanisms, allowed to guide the treatment, personalizing the clinical management, improving the quality of life, and cardiovascular outcomes in patients with MB.

The myocardial bridge: incidence, diagnosis, and prognosis of a pathology of uncertain clinical significance.

The myocardial bridge (MB) is a common anomaly of the coronary tree, very often clinically silent. The artery typically involved is the left anterior descending in its proximal and/or middle portion. MB can cause ischaemia with various mechanisms, directly proportional to the degree of compression of the intra-myocardial tract, which impairs the coronary flow. It is a dynamic phenomenon that is affected by the adrenergic tone and is therefore often brought by physical exercise. MB, when symptomatic, often begins with angina from exertion; some patients have more severe conditions such as unstable angina or myocardial infarction. Coronary vasospasm related to MB-induced endothelial dysfunction can explain a number of cases that come to observation even with catastrophic pictures such as ventricular fibrillation caused by ischaemia. The diagnostic workup includes the non-invasive study using computed tomography angiography and the invasive study of the haemodynamic impact using pressure and Doppler guides. In symptomatic cases, drug therapy with a beta-blocker is enough to manage angina. When it fails, there is the option of coronary angioplasty or surgical treatment techniques.

Rebound sign: a case report and review of literature.

We reviewed previously reported imaging features of coronary air embolism. We also reported an unusual image 'rebound sign' of proximal coronary artery air embolism for the first time, that is, with the regular contraction and relaxation of the heart, the contrast medium near the embolus rebounds regularly, and the smooth gas-liquid boundary is alternately clear and blurred. We conclude that myocardial bridge plays a role in the formation of 'rebound sign.'Abbreviations: CAE: Coronary Air Embolism; CAG: Coronary Angiography; RCA: Right Coronary Artery; LCA: Left Coronary Artery; LAD: Left Anterior Descending Coronary Artery; LCX: Left Circumflex Artery; MB: Myocardial Bridge; STEMI: ST Segment Elevation Myocardial Infarction; TOE: Transesophageal Echocardiography.

Severe myocardial bridge presenting as paroxysmal atrioventricular block.

Chest pain complicated with electrocardiographic changes is not an uncommon scenario in emergency departments, which should be examined cautiously. We describe a 51-years-old man with a myocardial bridge of coronary artery presenting with simultaneous Mobitz type I atrioventricular block on electrocardiography. Echocardiography excluded valvular abnormality and systolic/diastolic dysfunction. Coronary angiography confirmed the diagnosis of a myocardial bridge at the middle segment of the left anterior descending artery, involving the most dominant septal perforator branch with marked systolic compression. The patient underwent coronary artery bypass grafting surgery and was followed up uneventfully at the outpatient department with medical treatment of diltiazem and clopidogrel. The present case is being reported to highlight that clinicians should be alert to such a congenital abnormality as a potential cause of repeated myocardial infarction and conduction abnormality.

Anomalous Coronary Arteries: When to Follow-up, Risk Stratify, and Plan Intervention.

PURPOSE OF REVIEW: Coronary artery anomalies are a diverse group of entities, ranging from benign variations of normal anatomy to life-threatening conditions. There is, however, no universal consensus in their classification, risk stratification, and management. The aim of this review is to develop a straightforward clinical approach for the assessment and care of patients with anomalous coronary arteries. RECENT FINDINGS: Autopsy series and population screening studies have recently provided useful clinical data on the prevalence and outcomes of coronary anomalies. Also, findings on coronary computed tomography angiography, magnetic resonance imaging, and invasive angiography, enriched with fractional flow reserve and intravascular ultrasound, have allowed identification of several high-risk features associated with specific coronary anomalies. Management of patients with anomalous coronary arteries requires an individualized approach based on clinical, physiological, and anatomic features. High-quality studies are paramount for further development of this fascinating field.

Angiographic evidence of backward compression wave: systolic compression of septal perforators in a child with hypertrophic cardiomyopathy.

Intracoronary wave intensity analysis in hypertrophic cardiomyopathy has shown a large backward compression wave due to compressive deformation of the intramyocardial coronary arteries in systole. The authors describe the angiographic evidence of this backward compression wave, which has not been described in this physiological context and can be a marker of poor prognosis.

Recurrent attack of acute myocardial infarction complicated with ventricular fibrillation due to coronary vasospasm within a myocardial bridge: a case report.

BACKGROUND: Myocardial bridge (MB) often an inoffensive condition that goes in one or more of the coronary arteries through the heart muscle instead of lying on its surface. MBs sometimes leads to myocardial ischemic symptoms such as chest pain, even an occurrence of myocardial infarction. However, reports of severe and recurrent cardiac adverse events related to the MBs are rare. CASE PRESENTATION: A 44-year-old male patient who suffered from a four-hour crushing chest pain ten years ago, was diagnosed as acute anterior ST-elevation myocardial infarction (STEMI). The initial findings of coronary angiography (CAG) showed MB was located in the middle part of the left anterior descending coronary artery (LAD). The patient was managed medically. Another re-attack of similar previous chest pain characteristics occured just after 3 days of discharge. Supra-arterial myotomy and CABG were the next adopted management. Postoperative progression was uneventful. However, 32 months after surgical treatment, the patient experienced an abrupt onset of chest pain accompanied by loss of consciousness. The ECG showed ventricular fibrillation (VF). After electrical cardioversion, an immediate CAG followed by CTA was performed which excluded thrombus or acute occlusion in the native coronary artery and an occlusion was observed at the end of the left internal mammary artery. An implantable cardioverter-defibrillator (ICD) was successfully performed for prevention of malignant arrhythmia. During ten years of follow-up, no complications have been identified. CONCLUSIONS: Although MB is mostly benign, it may lead to significant cardiovascular consequences. Supra-arterial myotomy is an appropriate treatment option for this patient who failed to optimal medical therapy. Furthermore, ICD implantation must be considered in order to prevent malignant ventricular arrhythmia caused by continuous spasm resulting in ischemia. Further investigations are required to confirm the clinical effectiveness of these procedures.

Surgical treatment of symptomatic left anterior descending myocardial bridges: myotomy vs. bypass surgery.

PURPOSE: To compare the effects of myotomy and bypass surgery for treating myocardial bridges (MBs) over the left anterior descending artery (LAD) in a single-center observation study. METHODS: Fifty-four eligible patients (34 males, median age of 60 years old) with symptomatic LAD-MBs who underwent myotomy (31 patients) or bypass surgery (23 patients) were included in this study. The primary endpoints were the occurrence of major adverse cardiac events (MACEs) and angiographic demonstration of adverse angiographic results. RESULTS: No surgical death was observed. During a median follow-up of 26 months, 11 patients developed MACEs (7.4% for myotomy vs. 40.9% for bypass surgery, p = 0.007). Surgical strategy (bypass surgery vs. myotomy) was an independent risk factor for MACEs (odds ratio = 3.681, 95% confidence interval 1.814-8.685, p = 0.011). Myotomy compared with bypass surgery had a significantly lower incidence of adverse angiographic results (3.7% of residual compression vs. 40.9% of LIMA graft failure, p = 0.003). Among ten patients suffering from LAD-MBs with concomitant proximal coronary stenosis who underwent bypass surgery, only one reported transient recurrent exertional chest pain, and all LIMA grafts were patent. CONCLUSIONS: Myotomy of symptomatic LAD-MBs may be associated with encouraging midterm results. Bypass surgery may be recommended for treating symptomatic LAD-MBs with concomitant proximal coronary stenosis.

[Correlation between Coronary Artery Tortuosity and Stenosis in Patients with Myocardial Bridge].

Objective To analyze the correlation between tortuosity and stenosis in patients with myocardial bridge(MB)on the left anterior descending artery(LAD). Methods Data of patients with MB on the LAD,which was discovered by coronary computed tomography angiography(CCTA),in the Affiliated Hospital of North China University of Science and Technology from October 2015 to December 2018 were retrospectively analyzed.Among them 278 patients with tortuosity on LAD and 278 patients without tortuosity were selected.The clinical charateristics(age,gender,hypertension,hyperlipidemia,diabetes,smoking history,and family history)as well as the incidence and severity of stenosis of LAD were recorded and compared. Results The incidence of coronary artery stenosis in the non-tortuosity group(57.6%)was significantly lower than that in the tortuosity group(71.9%)($\bar{χ}$=12.608,P<0.001).It was also significantly higher in mild tortuosity group(78.5%)than in non-tortuosity group(57.6%)($\bar{χ}$=20.462,P<0.001)and moderate tortuosity group(61.5%)($\bar{χ}$=7.872,P=0.005).The degree of coronary artery stenosis was significantly different between tortuosity group and non-tortuosity group,and the tortuosity group was more likely to have more severe stenosis than the non-tortuosity group(Z=-3.292,P=0.001).The stenosis degree of the patients with no,mild,moderate and severe tortuosity was significantly different(H=17.787,P<0.001),and the differences had a rank correlation(rs=0.169,P=0.000).However,the incidence of stenosis was not significantly different among the none,moderate,and severe tortuosity groups(all P>0.05).There was no significant difference among the incidence of stenosis among the mild,moderate,and severe coronary artery tortuosity group(all P>0.05). Conclusions Patients with coronary artery tortuosity are more likely to have coronary artery stenosis than those without tortuosity.The stenosis rate in patients with mild tortuosity is higher than in patients without tornuosity or with moderate tortuosity.Patients with mild tortuosity are more likely to experience more severe stenosis,while those without tortuosity are more likely to have milder stenosis.

[Correlation of Transluminal Attenuation Gradientdistal with Corrected Contrast Opacification with Anterior Coronary Atherosclerosis].

Objective To explore the correlation between the transluminal attenuation gradient with corrected contrast opacification(TAG-CCO)and the severity of atherosclerotic stenosis in the anterior segment of myocrardial bridge(MB). Methods The imaging data of 200 patients diagnosed with left anterior descending branch(LAD)single MB and coronary atherosclerosis in the anterior segment of MB were retrospectively analyzed.According to MB types,the patients were divided into two groups:incomplete and complete.There were some significant differences in TAG-CCO between patients with the same degree of coronary atherosclerosis(mild,moderate,and severe stenosis)in two groups.The relationships among groups with different degrees(mild,moderate,and severe stenosis)of the same type of MB were further compared. Results Among 84 patients with complete MB,36,30,and 18 patients had mild,moderate,or severe coronary atherosclerosis in the anterior segment of MB;among 116 patients with incomplete MB,45,42,and 29 patients had mild,moderate,or severe coronary atherosclerosis in the anterior segment of MB.In the complete MB group,the TAG-CCO in the anterior segment of MB subgroups were(-0.0086±0.0014)/10 mm,(-0.0170±0.0180)/10 mm,and(-0.0230±0.0026)/10 mm,respectively,in mild,moderate,and severe subgroups(F = 404.728, P<0.001).In the incomplete MB group,the TAG-CCO of patients with mild,moderate and severe coronary stenosis in the anterior segment of MB were(-0.0039±0.0011)/10 mm,(-0.0100±0.0140)/10 mm,and(-0.0160±0.0020)/10 mm,respectively,and the difference among the different stenosis groups was statistically significant(F = 17.756, P < 0.001);the TAG-CCO of patients with mild(t = 16.519, P < 0.001),moderate(t = 2.570, P = 0.012)and severe anterior segment coronary stenosis(t = 10.714, P < 0.001)were significantly lower in the complete MB group than in the incomplete MB group. Conclusions TAG-CCO is correlated with the MB type and the degree of anterior coronary artery stenosis.Thus,TAG-CCO can be used as a predictive indicator for the degree of atheroscleratic stenosis in the anterior segment of MB.

Simulated coronary arterial hemodynamics of myocardial bridging.

The objective of this study was to explore the effects of myocardial bridge compression on blood flow, normal stress, circumferential stress and shear stress in mural coronary artery. An original mural coronary artery simulative device has been greatly improved and its measured hemodynamic parameters have been expanded from a single stress (normal stress) to multiple stresses to more fully and accurately simulate the true hemodynamic environment under normal stress, circumferential stress and shear stress. This device was used to more fully explore the relationship between hemodynamics and mural coronary atherosclerosis under the combined effects of multiple stresses. Results obtained from the mural coronary artery simulator showed stress abnormality to be mainly located in the proximal mural coronary artery where myocardial bridge compression was intensified and average and fluctuation values (maximum minus minimum) of proximal stress were significantly increased by 27.8% and 139%, respectively. It is concluded that myocardial bridge compression causes abnormalities in the proximal hemodynamics of the mural coronary artery. This is of great significance for understanding the hemodynamic mechanism of coronary atherosclerosis and has potential clinical value for the pathological effect and treatment of myocardial bridge.