Impending acute myocardial infarction during severe exercise associated with a myocardial bridge

Prevalence of myocardial bridges in the Mexican population: A morphometric and histological analysis

BACKGROUND

Myocardial bridge (MB) is described as an abnormal band of myocardium covering a variable portion of any coronary artery.

METHODS

The current study explores the presence of MB throughout the coronary arterial system and provides a morphometric description through instrumented dissection of a sample of 100 human hearts. The study shows a higher prevalence of MB in the Mexican population than in previous reports.

RESULTS

In the total sample (n=100), MB was identified in 96% of it. A total of 421 MBs were observed, with a mean of 4.38mm (±0.28) per dissected heart. The most frequently affected vessel is the anterior interventricular artery where a total of 52 MBs were found, of the total sample studied.

DISCUSSION

The high prevalence of MB among Mexican patients could be the result of a genetic association for this population or the neoformation of MB after birth due to lifestyle-associated factors. Further studies are required to better understand the high prevalence of MB among Mexican subjects.

The electrocardiogram as an adjunct in diagnosing congenital coronary arterial anomalies

Congenital coronary arterial abnormalities as isolated lesions are exceedingly rare. The electrocardiogram, while a reasonable adjunct in the diagnosis of coronary arterial abnormalities, should not supplant a good history and physical examination. Careful attention must be devoted to any signs or symptoms of ischaemic pain in the chest or syncope, which must not be overlooked. Exertional pain in the chest and exertional syncope should prompt an extensive evaluation by both the echocardiographer and the electrophysiologist. Clearance for participation in sports should be curtailed until a complete evaluation has ruled out the presence of any of the following disorders: a channelopathic mutation, a cardiomyopathy, or a congenital coronary arterial anomaly. Major abnormalities in the coronary arteries may present in the first few months of life or remain dormant until the exertional demands of adolescence unmask symptoms of myocardial ischaemia. Congenital coronary arterial anomalies may be analysed in the following major diagnostic groups: anomalous origin of the left coronary artery from the pulmonary artery, anomalous aortic origin of a coronary artery from the wrong aortic sinus of Valsalva, atresia of the left main coronary artery, myocardial bridges, and coronary arterial fistulas. The advent of state-of-the-art modalities of imaging seems, at times, to have supplanted the electrocardiogram in making the diagnosis of potentially serious coronary artery abnormalities, especially in asymptomatic patients. However, as is also the case for a detailed history and physical examination, the electrocardiogram provides a potentially insightful look at the coronary arteries. Furthermore, the past decade has witnessed an increase in the use of the electrocardiogram as a screening tool in the assessment of the risk of sudden cardiac death in athletes in high school.

A case of muscular bridge resulting in myocardial infraction following heavy effort: a case report

Muscular bridge (MB) is transient systolic coronary blockage occurring due to exposure of a portion of epicardial coronary arteries to compression during systole as a result of tunneling into the myocardium. Although rare, these patients may develop angina pectoris, severe arrhythmia and myocardial infraction (MI). A 30-year-old male patient presented to the emergency with severe pain with an onset at the front part of the chest followed by spreading to the back and arms, during a football match. The investigations performed revealed anterior wall infraction and thus thrombolytic treatment was administered. Patient's history was normal except for smoking. The patient was detected to play football occasionally since his childhood; however, we learnt that he had started playing without warm-up exercises at the last football match. Coronary angiography detected a lesion with an onset in the left anterior descending artery following the 1st diagonal and extending to the 2nd diagonal and exhibiting a significant contraction during systole. The patient was considered to have myocardial infraction secondary to myocardial bridge. Sudden deaths frequently occur in competitive sports requiring heavy effort.

Systolic Compression of Anomalous Large Septal Branch: an Unusual Cause of Myocardial Ischemia

Intramural course of coronary arteries is a well known phenomenon on autopsy. On angiography, however, it is usually seen in relation to the left anterior descending artery. Clinically, this entity may be associated with myocardial ischemia, infarction or sudden cardiac death. In this case, we report an unusual angiographic finding of first septal branch of left anterior descending artery. We present the case of a 43-year-old man with clinical and exercise ECG evidence of ischemia, whose primary abnormality is systolic compression of a long segment of anomalous large first septal branch.

The investigation of perivasculary space under the myocardial bridge in different species

Our purpose in this study was to investigate the perivasculary space under the myocardial bridges (MB) in dog, sheep, goat and human hearts. A total of 160 hearts were studied, and perivasculary space under the myocardial bridges was examined under microscope. The specimens belonged to 25 dogs, 100 sheep, 25 goats and 10 humans. Special attention was paid to evaluate the distance between the MB and coronary arteries (CA), CA and underlying myocardium (UM) and to find the relation of concomitant vein number accompanying the CA and MB. 219 myocardial bridges were found in total of hearts, and specimens from these bridges were examined under microscope. There were large variations in distance between the MB and CA (0-714 microm) and distance between CA and UM (0-309 microm). The myocardial bridges were classified into three groups in terms of the number of veins accompanying CA, the bridges with no concomitant veins with one concomitant vein and with two concomitant veins. This suggests that the distance between the MB and CA is crucial to determine how much force is on the CA. The environment surrounding the CA may be a crucial factor in determining whether the MB influences the induction of heart disorders or not.

Angiographic restenosis after myocardial bridge stenting

Data on restenosis after stent implantation in myocardial bridges (MB) are very limited. Six-month angiographic results for 12 symptomatic patients who underwent stent implantation for myocardial bridges were compared retrospectively with those of 39 patients who underwent direct stent implantation for de novo atherosclerotic lesions in the left anterior descending artery. Diameter stenosis decreased from 69 +/- 8% to 4 +/- 5% in the MB group and from 79 +/- 8% to 7 +/- 6% in the control group after stent deployment. Systolic narrowing was abolished in all patients with MB. In follow-up, quantitative angiography revealed late loss of 1.8 +/- 1.3 mm in the MB group and 0.9 +/- 0.9 mm in the control group (P = 0.025). The in-stent restenosis rate was also higher in the MB group compared to the control group (67% versus 28%; P = 0.037). Despite favorable immediate results, stent implantation in MBs may not be promising because of the higher in-stent restenosis rate compared to stenting in de novo atherosclerotic lesions.

Abnormal 201Tl myocardial single photon emission computed tomography in energetic male patients with myocardial bridge

Myocardial bridge is a relatively benign condition where a major coronary artery is bridged by a band of muscle and narrows during systole, particularly during rapid heart rates. Its clinical presentation and electrocardiogram (ECG) changes overlap with that of coronary artery disease. 201Tl myocardial perfusion imaging is thus frequently prescribed for further evaluation. This retrospective study was carried out to determine the 201Tl image patterns in patients with myocardial bridge. A total of 17 male patients (aged from 30 to 63 years) who had a positive exercise ECG and angiographic evidence of myocardial bridge in the mid-third of the left anterior descending coronary artery were recruited. Most of them were robust and received routine physical check-ups. They had no known heart disease or medication that affected cardiac function. The patients' clinical presentations, echocardiograph and exercise ECG findings were analysed. 201Tl single photon emission computed tomography (SPECT) was performed by intravenous injection of 201Tl (111 MBq) immediately following stress (treadmill or dipyridamole induced) and 4 h after stress, using a fixed, right angle camera equipped with a low energy, general purpose collimator. The images were interpreted independently by two experienced nuclear medicine physicians. Nine of the 17 patients had anterior chest pain during exercise. All patients had an abnormal ECG during exercise, including ST-T wave depression in leads II, III and aVF, and v4-6. Except for eight patients revealing reversible perfusion defect (R), 16 of the 17 patients also exhibited a partial reversible perfusion defect (PR) or a significant reverse redistribution (RR) scan pattern in the anterior or inferior walls of the left ventricle. Myocardial bridge should be taken into consideration in energetic male patients who had abnormal exercise ECGs and the corresponding patterns of Tl SPECT abnormalities including R, PR and RR.