Clinical and Angiographic Characteristics of Myocardial Bridges: a Descriptive Report of 19 Cases and Follow-up Outcomes

Background: Muscle fibers overlying the intramyocardial segment of an epicardial coronary artery are termed myocardial bridge (MB). The aim of this study was to analyze the mid-term outcome of MB and to examine its possible association with angiographic findings and concomitant cardiac pathologies such as hypertrophic cardiomyopathy (HCM). Methods: From a total of 3218 patients admitted for coronary angiography during 9 consecutive months, 28 (0.9%) were diagnosed with MBs with stenoses >=50%. Of these, 19 referred for follow-up with a median duration of 18 months. Results: HCM was present in 5 patients (26.3%), of whom 4 had MB as the sole finding in angiography. Of the 19 patients, 14 had diastolic dysfunction. In follow-up, 2 patients were treated with revascularization strategies due to the concomitant coronary artery disease and in 2, syncope occurred. For two patients, an intra-cardiac device and a permanent pacemaker were implanted. Three patients with MB as the sole finding in angiography were readmitted because of chest pain. Conclusion: Diastolic dysfunction may contribute to the presentation of symptoms of muscle bridging. Also, myocardial bridging as the only finding in coronary angiography is highly associated with hypertrophic cardiomyopathy and may help to detect this group of patients. The mid-term outcome of myocardial bridges is favorable

An Ovine Model of Dilated Cardiomyopathy Induced by Doxorubicin

Background: Dilated cardiomyopathy is associated with a progressive deterioration in cardiac function and eventually death. Initial interest in this hypothesis was to create another large animal model for dilated cardiomyopathy in addition to pigs and dogs.Methods: After the induction of anesthesia to 10 female sheep, a carotid-jugular shunt was created in all the animals via a 1-cm fistula between the carotid artery and jugular vein. Six sheep out of the total of 10, were given intravenous Doxorubicin. Echocardiographic studies were performed before surgery and 3 months after that. The 4 animals not injected with Doxorubicin were evaluated for echocardiographic parameters after one year. Results: There was no abnormality in echo parameters in the 4 sheep that had not received Doxorubicin; in addition, their valves and cardiac output were normal. As regards the six sheep injected with Doxorubicin, 4 received a dose of 2 mg/kg weekly and expired after the second injection due to the toxicity of the drug, 1 was given Doxorubicin 1 mg/kg and died after one week, and 1 had Doxorubicin 0.5 mg/kg but showed no abnormality in terms of dilated cardiomyopathy. Conclusion: We conclude that the sheep is sensitive to Doxorubicin and that the dosage that is enough for creating dilated cardiomyopathy in dogs is very toxic for the sheep