Eur J Cardiothorac Surg 2008;34:682-684. doi:10.1016/j.ejcts.2008.03.073
Copyright © 2008, European Association for Cardio-thoracic Surgery. Published by Elsevier. All rights reserved.
Off-pump supra-arterial myotomy for myocardial bridging
Alejandro Crespo,
José I. Aramendi*,
Gadah Hamzeh,
Roberto Voces
Division of Cardiac Surgery, Hospital de Cruces, Plaza de Cruces, Barakaldo 48903, Spain
Received 10 February 2008;
accepted 31 March 2008.
* Corresponding author. Tel.: +34 946006339. (Email: ji.aramendi{at}terra.es).
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Abstract
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We report the results of surgery and midterm outcome in two patients with symptomatic myocardial bridging who underwent off-pump supra-arterial myotomy. Both patients were operated upon through a median sternotomy. The anterior wall of the heart was exposed in the same manner as in off-pump CABG. The left anterior descending coronary artery is unroofed from its myocardial bridge with the aid of a heart stabilizer and a blower. Neither heparin nor blood transfusion was required. Both patients survived the operation and are asymptomatic. Postoperative coronary angiogram showed good resolution of the muscle bridge in one patient. We conclude that in symptomatic patients with myocardial bridging despite medical therapy, surgical myotomy can be considered an adequate therapy. It can be safely done off-pump.
Key Words: Coronary artery disease • Ischemia • Off-pump • Revascularization
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1. Introduction
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We report the results of surgery and midterm outcome in two patients with symptomatic myocardial bridging who underwent off-pump supra-arterial myotomy.
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2. Case report
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2.1 Patient 1
A 54-year-old man with effort induced angina for 2 years was admitted because of continuing chest pain despite therapy. In 2000 a selective coronary angiography showed a myocardial bridging in the proximal left anterior descending (LAD) artery about 2 cm in length (Fig. 1
); Exercise tolerance test was positive despite having β-blockers. The patient underwent an operation in October 2001. Under off-pump surgery the LAD was completely unroofed of its myocardial bridge. The postoperative course was uneventful and he was asymptomatic and discharged on calcium blockers therapy. One year after surgery, his exercise test was negative for ischemia.
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Fig. 1. Coronary angiography. (A) Preoperative angiogram, case 1. Arrow shows a 2 cm long systolic milking of the LAD. (B) Case 2. Arrow shows a 7 cm long systolic milking. (C) Case 2. Diastolic opening of LAD. (D) Postoperative angiogram of case 2: complete relief of milking.
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2.2 Patient 2
A 64-year-old woman with history of angina both at rest and on effort was admitted for cardiac examination. She had no identifiable risk factors for atherosclerosis. Physical examination, chest radiography and laboratory tests were normal. EKG showed negative T-wave in leads V1 to V2. On echocardiography, left ventricular ejection fraction was 75% with normal regional wall motion. Selective coronary angiography showed a 7 cm long segment of medial and distal LAD with severe obliteration during systole characteristic of tight myocardial bridging (milking effect) (Fig. 1).
All the other coronary vessels appeared normal. During hospitalization the patient continued to have severe episodes of chest pain despite therapy. The patient underwent an operation on June 2007. Off-pump unroofing of the myocardial bridge was performed through median sternotomy. During the postoperative period the patient continued having chest discomfort with normal EKG. A postoperative catheterization was performed: no systolic narrowing of the LAD could be visualized (Fig. 1). She was discharged on β-blockers.
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3. Surgical technique
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Under general anesthesia a median sternotomy is performed. The anterior wall of the heart is exposed in the same manner as in off-pump coronary artery bypass graft (CABG). The distal LAD is easily identified as it emerges from the myocardial bridge in the epicardial fat. A Chase Medical (Richardson, Texas) coronary stabilizer is applied on the most distal part of the muscle bridge. This stabilizer has a broad base and two rotating arms that open the trench that is created in the epicardial fat and myocardium facilitating the exposure of the coronary artery (Fig. 2
, Video 1). Sharp dissection is performed with a Beaver scalpel until the anterior wall of the LAD is completely exposed. Venous bleeding is flushed away with a CO2 and saline blower, Research Medical (Edwards Lifesciences, Irvine, California). As the distal part of the LAD is freed the stabilizer is moved cephalad until the whole length of the intramyocardial artery is liberated (Video 2). Generally, a 5–7 cm length and 5 mm deep trench is created. Usually, no hemostatic sutures are required and blood loss is minimal. Neither heparin nor blood transfusion is required. The sternotomy is closed in the usual manner.
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Fig. 2. (A) Rotating pads of the Chase stabilizer open the muscle trench. (B) Surgical view: the LAD is completely exposed.
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4. Discussion
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Myocardial bridging is defined as a segment of a major epicardial coronary artery that runs intramurally through the myocardium [1]. It was Reyman in 1737 who was first to mention and call the running coronary artery segment within the myocardium as tunnelled artery [2,1]. The LAD is the most affected coronary artery. The incidence of this anomaly changes according to the type of study used, from 15% to 85% at autopsy and 0.5% to 2.5% at angiography [1]. Its typical angiographic presentation is the systolic milking effect due to transient compression of the vessel by the myocardium [3]. A high prevalence has been reported in heart transplant recipients and in patients with hypertrophic cardiomyopathy [2].
Although myocardial bridging is usually associated with a benign prognosis it may lead to myocardial ischemia and infarction, left ventricular systolic dysfunction, conduction disturbances, exercise-induced ventricular tachycardia, and sudden death.
It has been thought that systolic compression is not the only cause of ischemia because myocardial perfusion is achieved mainly during diastole. Endothelial cell damage, continuous mechanical stress that predisposes the tunnelled segment of a coronary artery to vasospasm, and premature atherosclerosis on the coronary artery proximal to the myocardial bridging segment may contribute to ischemia [2].
Beta adrenergic blockers are the first choice for relieving angina on symptomatic myocardial bridging [3]. In patients with refractory angina despite medical therapy, coronary stenting, myotomy, or coronary bypass can be considered as an alternative treatment.
- (1) Stent implantation. In 1995 Stables et al. [4] first reported coronary stenting as an interventional approach to severe myocardial bridging refractory to medication. Approximately 50% of these patients developed restenosis and major periprocedural complications. This approach is not generally recommended in symptomatic patients [5].
- (2) CABG, either on-pump or off-pump, has been used to treat myocardial bridging [6]. Although it may alleviate angina, it does not cure the disease. It leaves a proximal muscle bridge that may trigger coronary and internal mammary artery spasm. Besides, competitive blood flow may occur in diastole since there is not a fixed stenosis.
- (3) Surgical myotomy. In patients with angina refractory to medication, surgical myotomy, first reported by Binet et al. [7], abolishes clinical symptoms and is associated with reversal of local myocardial ischemia and an increase in coronary blood flow [8]. Supra-arterial decompressive myotomy not only treats the physiologic abnormality of myocardial bridging, but corrects the congenital anatomic defect [9,10]. Until now, this unroofing technique has been done using cardiopulmonary bypass and cardiac arrest. In the beginning of OPCAB the presence of an intramyocardial course of a coronary branch was considered a major contraindication of the technique. With growing experience, off-pump revascularization is achieved in the presence of a myocardial bridge. To our best knowledge, this is the first report of off-pump unroofing of a myocardial bridge. With the aid of a heart stabilizer it is safe and reproducible. It eliminates the morbidity associated with the cardiopulmonary bypass and the need for transfusion.
We conclude that in symptomatic patients with myocardial bridging despite medical therapy, myotomy can be considered an adequate therapy. It can be safely done off-pump.
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Appendix A
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Supplementary data
Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.ejcts.2008.03.073.
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References
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Abstract
1. Introduction
