Myocardial bridge, surgery or stenting
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《血管的通路杂志》
a Department of Cardiovascular Surgery, Cardiovascular Institute, Fu Wai Hospital, Chinese Academy of Medical Science, Peking Union Medical College, 167 Bei Li Shi Road, Fuchengmenwai, Beijing, China
b Department of Cardiovascular Surgery, Cardiovascular Institute, The First Affiliated Hospital of Tsinghua University, Beijing, China
Abstract
This report reviews the clinical experience of surgical treatment and stent implantation for myocardial bridge over the past 7 years at Fu Wai Hospital. Operations were performed on 15 patients for myocardial bridge. There were 10 male and 5 female patients aged from 35 to 67 years (mean age, 49.2 years). Nine of them were associated with other cardiac diseases and the remaining six were MB only. Another 4 patients accepted stent implantation. There were 3 male patients and 1 female patient with a mean age of 57.6 years ranging from 46 to 66 years. All of them were for MB only. In the surgical group 8 patients underwent coronary artery bypass grafting by using the other internal mammary artery and the 7 underwent myotomy on myocardial bridge. All patients survived the operation and recovered uneventfully. Follow-up showed no late death, readmission, or angina complaint. The patients in the stenting group got excellent angiography results after intervention. Follow-up showed that two patients had typical angina within 3 months and 7 months, respectively, after stenting and readmission. The post-angiography showed that moderate intimal proliferation and systolic compression still existed in these patients. Excellent early and late surgical results were obtained in all patients. Compared with stenting, surgical treatment may be a better choice.
Key Words: Myocardial bridge; Surgical treatment; Stent implantation
1. Introduction
Myocardial bridge (MB) has generally been viewed as a congenital anomaly of the coronary arteries and has been characterized by systolic compression of part of an epicardial vessel by a segment of overlying myocardium [1]. The reported prevalence of MB at autopsy varies from 5.4% to 85.7% and 0.5% to 16% on angiography [2]. MB is usually a benign condition with an excellent long-term survival but has been implicated in causing myocardial ischemia [3], myocardial infarction [4], exercise-induced tachycardia [5], paroxysmal AV blockade [6], and sudden cardiac death [7]. Negative inotropic and/or negative chronotropic agent [8, 9], coronary artery bypass grafting [10], excision of the overlying muscle band [11], and stenting [12] have been used to treat patients with myocardial ischemia attributed to a muscle bridge. Most reports about MB are based on scattered cases. This report reviews our clinical experience with stenting and surgical treatment on MB at Fu Wai Hospital over the past 7 years.
2. Patients and methods
There were 109 patients who were diagnosed with MB by coronary angiography in Fu Wai Hospital from 1997 to November 2004. Nine of them were asymptomatic and no treatments were performed. Eighty-one patients were responsible for medication. The remaining 19 patients were refractory to medication. Fifteen patients underwent operation and 4 patients accepted stent implantation. All patients signed an informed consent for having these procedures and was approved by the Ethics Committee of Fu Wai hospital. Data were obtained from medical records. All these patients were symptomatic and had a reversible perfusion detected in LAD territory in a Tc-99 m sestamibi SPECT test performed before coronary angiography to confirm ischemia. In addition, 11 patients had a positive exercise ECG test with 1 mm horizontal or downsloping ST segment depression in at least two contiguous leads. Thirteen patients accepted ergonovine provoking during angiography and no spasm was induced. Survivors were contacted by letter and telephone. Follow-up of all patients ranged from 6 months to 75 months (mean follow-up, 23.5 months) and the follow-up angiography was also documented.
3. Results
3.1. Surgical treatment group
There were 10 male patients and 5 female patients with a mean age of 49.2 years ranging from 35 to 67 years. Six patients were MB only; 2 patients were MB with hypertrophic obstructive cardiomyopathy (HOCM); 2 patients were MB with coronary heart disease and the remainder were associated with valve diseases. Twelve of them had a history of stable angina and more frequent paroxysm several months later. Eight patients underwent coronary artery bypass grafting (CABG) and 7 patients underwent myotomy according to surgeon preference. The procedure of cardiopulmonary bypass (CPB) was adopted in 11 patients and the off-pump technique was adopted in another four. The mean CPB time was 93 min (from 40 min to 139 min). The mean crossclamp time was 68 min (from 8 min to 113 min). There was no hospital death. Complete recovery was achieved in the postoperative period in all patients. Follow-up of all patients ranged from 6 months to 75 months (mean follow-up, 22.5 months) and showed no complaint of angina and readmission. Postoperative angiography was performed in 12 patients from 11 months follow-up to 24 months follow-up. Nothing abnormal was found. The detailed pre- and postoperative angiographic findings and operative maneuver are shown in Table 1 (Figs. 1 and 2).
3.2. Stenting group
There were 3 male patients and 1 female patient with a mean age of 57.6 years ranging from 46 to 66 years. All of them were MB only. They all had a history of stable angina and more frequent paroxysm several months later and refractory to medication. All of their coronary angiograms revealed an MB in the middle of LAD and also systolic compression 75% (ranging from 75% to 90%). Coronary interventions were performed using an NIR stent with excellent angiographic results. They all remained pain-free in the hospital. Follow-up ranged from 26 to 46 months and showed that only two patients were markedly improved with only occasional pain and no readmission. The other two patients had typical angina within 3 months and 7 months, respectively, after stenting and had to be readmitted. The postangiography showed that moderate intimal proliferation and systolic compression still existed in these two patients. One underwent CABG at a local hospital 14 months after stenting and had no complaint of angina. The other one was treated with medication.
4. Discussion
The first mention of an intramyocardial course of a segment of an epicardial coronary artery was made by Reyman in 1737 [13], although the first angiographic description was not reported until 1960 [14]. Myocardial bridge is a distinctive anatomical entity whose pathophysiological role has brought about much controversy. The standard for diagnosing MB now is coronary angiography with the typical ‘milking effect’ and a ‘step down–step up’ phenomenon induced by systolic compression of the tunneled vessel. The new imaging techniques, such as intravascular ultrasound (IVUS) and intracoronary Doppler ultrasound (ICD), have provided better identification and functional quantitation to establish a link between systolic compression and the clinical presentation.
The LAD is the most clinically important vessel that is affected by MB. Anatomical studies run between the proximal third and middle third of the LAD. Someone reported that MB appeared in multiple sites such as PDA and RCA [15]. In our review, two patients were found with MB at multiple sites including PDA and OM1. Seventeen patients had a single MB at the midportion of the LAD.
In symptomatic patients, three treatment strategies have been explored: (1) medical treatment includes optimal doses of negative inotropic and/or negative chronotropic agents with the objetive of relieving symptoms and/or protecting against the risk of future coronary events [8,9]; (2) coronary stenting in MB [12]; and (3) surgical myotomy and/or CABG [10,11]. Medical treatment is the first choice. Most of the 109 patients with MB can be alleviated by medication. However, long-term follow-up is needed to validate these results. To the patients who were refractory to the medication, at first both of stenting and surgery were recommended in our hospital. Now, according to the follow-up results, we prefer to adopt surgical treatment because stent placement has been complicated by intimal proliferation. Thrombus formation, and restenosis, and stent compression are also matters for concern. Also, we are short of randomized data to demonstrate the efficacy of stenting in the tunneled vessel in the long run.
We consider that the patients who are refractory to medication should undergo the surgical treatment when the compression of LAD is 75%. Obvious myocardial ischemia or myocardial infarction are also a surgical indication. Surgical myotomy was an earlier technique that applied to MB. Although there were some risky reports, including mural aneurysm and scar formation with subsequent recurring vessel compression [11], we consider myotomy is suitable for all MB patients (Figs. 3 and 4). Careful separation and thorough excision of the overlying muscle band are the keys for operation. In our review, one patient suffered a right ventricular perforation that was successfully repaired while we attempted to perform myotomy. CABG was also applied to MB. The LIMA may be the best choice for grafting. We prefer to adopt myotomy because CABG has its shortcomings including restenosis and hemorrhage. When surgery is chosen, the procedure of ‘on or off’ pump should be determined by the surgical expertise of the institution and individual surgeon.
Here we report 9 patients of MB with different types of heart diseases. Because the symptom of ischemia may be covered preoperatively, and it may be aggravated postoperatively, it should be more active to treat with MB when it is associated with another cardiac disease such as CHD heart valve disease. Four of the patients underwent surgical treatment when the compression reached 50%. All patients completely recovered and the postoperative courses were uneventful.
5. Conclusion
Surgical treatment may be a better choice for patients who are refractory to medication. Myotomy should be advocated because of its good results. Finally, we should be more positive in applying an operation to patients with MB who are associated with other heart diseases.
References
Vongpatanasin W, Willard JE, Hillis LD, Lange RA, Landau C. Acquired myocardial bridging. Am Heart J 1997;133:463–465.
Kramer JR, Kitazume H, Proudfit WL, Sones FM Jr. Clinical significance of isolated coronary bridges, benign and frequent condition involving the left anterior descending artery. Am Heart J 1982;103:283–288.
Arnau Vives MA, Martimez Dolz LV, Almenar Bonet L, Lalaguna LA, Ten Morro F, Palencia Perez M. Myocardial bridging as a cause of acute ischemia: description of a case and review of the literature. Rev Exp Cardiol 1999;52:441–444.
Yano K, Yoshino H, Taniuchi M, Kachi E, Shimizu H, Watanuki A. Myocardial bridging of the LAD in acute inferior wall myocardial infarction. Clin Cardiol 2001;24:202–208.
Feld H, Guadanino V, Hollander G, Greengart A, Lichstein E, Shani J. Exercise induced ventricular tachycardia in association with a myocardial bridge. Chest 1991;99:1295–1296.
den Dulk K, Brugada P, Braat S, Heddle B, Wellens HJ. Myocardial bridging as a cause of paroxysmal atrioventricular block. J Am Coll Cardiol 1983;1:965–969.
Cutler D, Wallace JM. Myocardial bridging in a young patient with sudden death. Clin Cardiol 1997;20:581–583.
Nair CK, Dang B, Heintz MH, Sketch MH. Myocardial bridges: effect of propanolol on systolic compression. Can J Cardiol 1986;2:218–221.
Kracoff OH, Ovsyshcher I, Gueron M. Malign course of a benign anomaly: myocardial bridging. Chest 1987;92:1113–1115.
Mardi GM, Michael CK, Valentin F. A stratified approach to the treatment of a symptomatic myocardial bridge. Clin Cardiol 2002;25:484–486.
Parashara DK, Ledley GS, Kotler MN, Yazdanfar S. The combined presence of myocardial bridging and fixed coronary artery stenosis. Am Heart J 1993;125:1170–1172.
Berry JF, von Mering GO, Schmalfuss C, Hill JA, Kerensky RA. Systolic compression of the left anterior descending coronary artery: a case series, review of the literature, and therapeutic options including stenting. Catheter Cardiovasc interven 2002;56:58–63.
Reyman HC. Disertatio de vasis cordis propriis. Sept 7th, 1737;1–32.
Porstnann W, Iwing J. Die intramurale Koronaroerterie im angiogramm. Fortschr Geb Rontgenstr 1960;12:129–132.
Wu WS, Chen ZC, Wang SH, Huang TY. Multiple myocardial bridging in patients with hypertrophic cardiomyopathy: report of two cases. Acta Cardiol Sin 2002;18:197–200.(Li Wan, and Qingyu Wu)
b Department of Cardiovascular Surgery, Cardiovascular Institute, The First Affiliated Hospital of Tsinghua University, Beijing, China
Abstract
This report reviews the clinical experience of surgical treatment and stent implantation for myocardial bridge over the past 7 years at Fu Wai Hospital. Operations were performed on 15 patients for myocardial bridge. There were 10 male and 5 female patients aged from 35 to 67 years (mean age, 49.2 years). Nine of them were associated with other cardiac diseases and the remaining six were MB only. Another 4 patients accepted stent implantation. There were 3 male patients and 1 female patient with a mean age of 57.6 years ranging from 46 to 66 years. All of them were for MB only. In the surgical group 8 patients underwent coronary artery bypass grafting by using the other internal mammary artery and the 7 underwent myotomy on myocardial bridge. All patients survived the operation and recovered uneventfully. Follow-up showed no late death, readmission, or angina complaint. The patients in the stenting group got excellent angiography results after intervention. Follow-up showed that two patients had typical angina within 3 months and 7 months, respectively, after stenting and readmission. The post-angiography showed that moderate intimal proliferation and systolic compression still existed in these patients. Excellent early and late surgical results were obtained in all patients. Compared with stenting, surgical treatment may be a better choice.
Key Words: Myocardial bridge; Surgical treatment; Stent implantation
1. Introduction
Myocardial bridge (MB) has generally been viewed as a congenital anomaly of the coronary arteries and has been characterized by systolic compression of part of an epicardial vessel by a segment of overlying myocardium [1]. The reported prevalence of MB at autopsy varies from 5.4% to 85.7% and 0.5% to 16% on angiography [2]. MB is usually a benign condition with an excellent long-term survival but has been implicated in causing myocardial ischemia [3], myocardial infarction [4], exercise-induced tachycardia [5], paroxysmal AV blockade [6], and sudden cardiac death [7]. Negative inotropic and/or negative chronotropic agent [8, 9], coronary artery bypass grafting [10], excision of the overlying muscle band [11], and stenting [12] have been used to treat patients with myocardial ischemia attributed to a muscle bridge. Most reports about MB are based on scattered cases. This report reviews our clinical experience with stenting and surgical treatment on MB at Fu Wai Hospital over the past 7 years.
2. Patients and methods
There were 109 patients who were diagnosed with MB by coronary angiography in Fu Wai Hospital from 1997 to November 2004. Nine of them were asymptomatic and no treatments were performed. Eighty-one patients were responsible for medication. The remaining 19 patients were refractory to medication. Fifteen patients underwent operation and 4 patients accepted stent implantation. All patients signed an informed consent for having these procedures and was approved by the Ethics Committee of Fu Wai hospital. Data were obtained from medical records. All these patients were symptomatic and had a reversible perfusion detected in LAD territory in a Tc-99 m sestamibi SPECT test performed before coronary angiography to confirm ischemia. In addition, 11 patients had a positive exercise ECG test with 1 mm horizontal or downsloping ST segment depression in at least two contiguous leads. Thirteen patients accepted ergonovine provoking during angiography and no spasm was induced. Survivors were contacted by letter and telephone. Follow-up of all patients ranged from 6 months to 75 months (mean follow-up, 23.5 months) and the follow-up angiography was also documented.
3. Results
3.1. Surgical treatment group
There were 10 male patients and 5 female patients with a mean age of 49.2 years ranging from 35 to 67 years. Six patients were MB only; 2 patients were MB with hypertrophic obstructive cardiomyopathy (HOCM); 2 patients were MB with coronary heart disease and the remainder were associated with valve diseases. Twelve of them had a history of stable angina and more frequent paroxysm several months later. Eight patients underwent coronary artery bypass grafting (CABG) and 7 patients underwent myotomy according to surgeon preference. The procedure of cardiopulmonary bypass (CPB) was adopted in 11 patients and the off-pump technique was adopted in another four. The mean CPB time was 93 min (from 40 min to 139 min). The mean crossclamp time was 68 min (from 8 min to 113 min). There was no hospital death. Complete recovery was achieved in the postoperative period in all patients. Follow-up of all patients ranged from 6 months to 75 months (mean follow-up, 22.5 months) and showed no complaint of angina and readmission. Postoperative angiography was performed in 12 patients from 11 months follow-up to 24 months follow-up. Nothing abnormal was found. The detailed pre- and postoperative angiographic findings and operative maneuver are shown in Table 1 (Figs. 1 and 2).
3.2. Stenting group
There were 3 male patients and 1 female patient with a mean age of 57.6 years ranging from 46 to 66 years. All of them were MB only. They all had a history of stable angina and more frequent paroxysm several months later and refractory to medication. All of their coronary angiograms revealed an MB in the middle of LAD and also systolic compression 75% (ranging from 75% to 90%). Coronary interventions were performed using an NIR stent with excellent angiographic results. They all remained pain-free in the hospital. Follow-up ranged from 26 to 46 months and showed that only two patients were markedly improved with only occasional pain and no readmission. The other two patients had typical angina within 3 months and 7 months, respectively, after stenting and had to be readmitted. The postangiography showed that moderate intimal proliferation and systolic compression still existed in these two patients. One underwent CABG at a local hospital 14 months after stenting and had no complaint of angina. The other one was treated with medication.
4. Discussion
The first mention of an intramyocardial course of a segment of an epicardial coronary artery was made by Reyman in 1737 [13], although the first angiographic description was not reported until 1960 [14]. Myocardial bridge is a distinctive anatomical entity whose pathophysiological role has brought about much controversy. The standard for diagnosing MB now is coronary angiography with the typical ‘milking effect’ and a ‘step down–step up’ phenomenon induced by systolic compression of the tunneled vessel. The new imaging techniques, such as intravascular ultrasound (IVUS) and intracoronary Doppler ultrasound (ICD), have provided better identification and functional quantitation to establish a link between systolic compression and the clinical presentation.
The LAD is the most clinically important vessel that is affected by MB. Anatomical studies run between the proximal third and middle third of the LAD. Someone reported that MB appeared in multiple sites such as PDA and RCA [15]. In our review, two patients were found with MB at multiple sites including PDA and OM1. Seventeen patients had a single MB at the midportion of the LAD.
In symptomatic patients, three treatment strategies have been explored: (1) medical treatment includes optimal doses of negative inotropic and/or negative chronotropic agents with the objetive of relieving symptoms and/or protecting against the risk of future coronary events [8,9]; (2) coronary stenting in MB [12]; and (3) surgical myotomy and/or CABG [10,11]. Medical treatment is the first choice. Most of the 109 patients with MB can be alleviated by medication. However, long-term follow-up is needed to validate these results. To the patients who were refractory to the medication, at first both of stenting and surgery were recommended in our hospital. Now, according to the follow-up results, we prefer to adopt surgical treatment because stent placement has been complicated by intimal proliferation. Thrombus formation, and restenosis, and stent compression are also matters for concern. Also, we are short of randomized data to demonstrate the efficacy of stenting in the tunneled vessel in the long run.
We consider that the patients who are refractory to medication should undergo the surgical treatment when the compression of LAD is 75%. Obvious myocardial ischemia or myocardial infarction are also a surgical indication. Surgical myotomy was an earlier technique that applied to MB. Although there were some risky reports, including mural aneurysm and scar formation with subsequent recurring vessel compression [11], we consider myotomy is suitable for all MB patients (Figs. 3 and 4). Careful separation and thorough excision of the overlying muscle band are the keys for operation. In our review, one patient suffered a right ventricular perforation that was successfully repaired while we attempted to perform myotomy. CABG was also applied to MB. The LIMA may be the best choice for grafting. We prefer to adopt myotomy because CABG has its shortcomings including restenosis and hemorrhage. When surgery is chosen, the procedure of ‘on or off’ pump should be determined by the surgical expertise of the institution and individual surgeon.
Here we report 9 patients of MB with different types of heart diseases. Because the symptom of ischemia may be covered preoperatively, and it may be aggravated postoperatively, it should be more active to treat with MB when it is associated with another cardiac disease such as CHD heart valve disease. Four of the patients underwent surgical treatment when the compression reached 50%. All patients completely recovered and the postoperative courses were uneventful.
5. Conclusion
Surgical treatment may be a better choice for patients who are refractory to medication. Myotomy should be advocated because of its good results. Finally, we should be more positive in applying an operation to patients with MB who are associated with other heart diseases.
References
Vongpatanasin W, Willard JE, Hillis LD, Lange RA, Landau C. Acquired myocardial bridging. Am Heart J 1997;133:463–465.
Kramer JR, Kitazume H, Proudfit WL, Sones FM Jr. Clinical significance of isolated coronary bridges, benign and frequent condition involving the left anterior descending artery. Am Heart J 1982;103:283–288.
Arnau Vives MA, Martimez Dolz LV, Almenar Bonet L, Lalaguna LA, Ten Morro F, Palencia Perez M. Myocardial bridging as a cause of acute ischemia: description of a case and review of the literature. Rev Exp Cardiol 1999;52:441–444.
Yano K, Yoshino H, Taniuchi M, Kachi E, Shimizu H, Watanuki A. Myocardial bridging of the LAD in acute inferior wall myocardial infarction. Clin Cardiol 2001;24:202–208.
Feld H, Guadanino V, Hollander G, Greengart A, Lichstein E, Shani J. Exercise induced ventricular tachycardia in association with a myocardial bridge. Chest 1991;99:1295–1296.
den Dulk K, Brugada P, Braat S, Heddle B, Wellens HJ. Myocardial bridging as a cause of paroxysmal atrioventricular block. J Am Coll Cardiol 1983;1:965–969.
Cutler D, Wallace JM. Myocardial bridging in a young patient with sudden death. Clin Cardiol 1997;20:581–583.
Nair CK, Dang B, Heintz MH, Sketch MH. Myocardial bridges: effect of propanolol on systolic compression. Can J Cardiol 1986;2:218–221.
Kracoff OH, Ovsyshcher I, Gueron M. Malign course of a benign anomaly: myocardial bridging. Chest 1987;92:1113–1115.
Mardi GM, Michael CK, Valentin F. A stratified approach to the treatment of a symptomatic myocardial bridge. Clin Cardiol 2002;25:484–486.
Parashara DK, Ledley GS, Kotler MN, Yazdanfar S. The combined presence of myocardial bridging and fixed coronary artery stenosis. Am Heart J 1993;125:1170–1172.
Berry JF, von Mering GO, Schmalfuss C, Hill JA, Kerensky RA. Systolic compression of the left anterior descending coronary artery: a case series, review of the literature, and therapeutic options including stenting. Catheter Cardiovasc interven 2002;56:58–63.
Reyman HC. Disertatio de vasis cordis propriis. Sept 7th, 1737;1–32.
Porstnann W, Iwing J. Die intramurale Koronaroerterie im angiogramm. Fortschr Geb Rontgenstr 1960;12:129–132.
Wu WS, Chen ZC, Wang SH, Huang TY. Multiple myocardial bridging in patients with hypertrophic cardiomyopathy: report of two cases. Acta Cardiol Sin 2002;18:197–200.(Li Wan, and Qingyu Wu)