Series: Vascular Pathology (1) Coronary Events Caused by Myocardial Bridge

Challenges in Evaluation and Management of Children with Myocardial Bridging

Myocardial bridging (MB) is a congenital anomaly where a coronary artery branch or group of branches extends inside a tunnel consisting of myocardium. Although it is mostly considered "benign," it is reported that MB may lead to significant cardiac problems and sudden cardiac deaths. While it is a congenital anomaly, its symptoms usually arise at further ages rather than childhood. The literature on MB in children is in the form of case reports or small case series. This is why pediatric cases are assessed in the light of information obtained from adults. This review compiled the literature on MB in adults and children and compared it, as well as discussing questions arising regarding the clinic, diagnosis, and treatment of MB.

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.

Coronary artery perforation in a patient with STEMI and a myocardial bridge: an increased risk for coronary artery perforation?

We present the case of a patient with ST-elevation myocardial infarction (STEMI) due to subtotal occlusion of the left anterior descending coronary artery caused by an atherosclerotic lesion and a myocardial bridge (MB). Stenting of the MB caused coronary artery perforation resulting in a fistula to the right ventricle that was closed by implantation of a PTFE-covered stent. Follow-up coronary angiography showed persistent shunting, which was sealed by inflation of a high-pressure balloon over the site of extravasation guided by intravascular ultrasound. Additionally, we provide a short review of cases with coronary artery perforation after stenting of an MB.

Myocardial bridge as a structure of "double-edged sword" for the coronary artery

Myocardial bridge (MB) is a chance anatomical structure, comprised of the myocardial tissue, with which the coronary artery running in epicardial adipose tissue is partly covered. It is predominantly present in the left anterior descending artery (LAD) and recognizable through imaging techniques as changes in blood flow within the LAD that arises from MB contraction at cardiac systole. Such changes in blood flow influence the pathophysiology of coronary circulation and atherosclerosis development, thus generating controversy as to whether MB predisposes individual to myocardial infarction (MI). However, recent histomorphometric studies have shown that the individual anatomic properties of MB, such as location, length and thickness, consistently play a critical role in the occurrence of MI. This review article comprehensively addresses the pathophysiological mechanisms of MI occurrence together with the benign suppressive effect of coronary atherosclerosis by MB.