Myocardial bridging

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Rim Halaby, M.D. [2]

Synonyms and Keywords: myocardial bridge, coronary bridge, coronary artery bridge, coronary bridging, coronary artery bridging

Overview

A myocardial bridge is defined as a segment of a major coronary epicardial artery that "tunnels" or passes intramurally through the myocardium beneath the muscle bridge during systole.[1][2] Myocardial bridges are generally located in the distribution of the left anterior descending artery (LAD) and its diagonal branches.

Myocardial bridging should be distinguished from intramyocardial course, which is an inborn coronary anomaly defined as a segment of a major epicardial coronary artery running and ending in the myocardium.

Historical Perspective

Angiographically, myocardial bridging was first recognized in the 1960's.[3]

Pathophysiology

Variants

There are two basic morphologic variants:

Extent

Majority of the cases, systolic bridging is usually not severe or extensive and completely reverses during diastole; except in patients with HOCM, wherein severe systolic bridging of the septal perforators may be a predisposing factor to the development of myocardial ischemia.[4][5][6][7][8][9]

Epidemiology and Demographics

The reported frequency varies with different modalities used to identify myocardial bridges. Generally, with coronary angiography, the reported frequent ranges from 0.5-16% [2][1][10][4][11][12][13][14] and with pathological or coronary CT, the frequency is between 5-86%.[2][1][15][16][17][18]

Irrespective of the modality used, the left anterior descending coronary artery is most commonly involved and a higher incidence is observed in patients with hypertrophic coronary artery and cardiac transplants.[2][14] Among the pediatric age group, the occurrence of myocardial bridging is rare but an increased incidence may be observed in association with hypertrophic cardiomyopathy.

Natural History, Complications and Prognosis

Complications

Complications of myocardial bridging include the following:

Prognosis

The combined presence of hypertrophic cardiomyopathy and myocardial bridging is associated with a worse prognosis as compared to hypertrophic cardiomyopathy alone[19].

Diagnosis

Coronary Angiography

Case 1

Shown below is an animated image depicting myocardial bridge.

Myocardial bridging


Shown below are two static images of the same case depicting myocardial bridge. Outlined with yellow in the image on the left is the part of the coronary artery during diastole. This same part of the coronary artery is outlined in yellow in the image on the right during systole; note that this outlined part is narrowed compared to its shape during diastole.

Shape of the coronary artery during diastole The coronary artery is narrowed during systole which is consistent myocardial bridging.


Case 2

Shown below are an animated image and a static image depicting myocardial bridge.

Myocardial bridging Myocardial bridging

Intracoronary ultrasound

Treatment

Medical Treatment

PCI/Stenting

  • Stenting can abolish hemodynamic abnormalities associated with myocardial bridging and may improve clinical symptoms in patients with myocardial bridges.[26][27]
  • Care must be exercised in stent placement to assure that the bridge is not just moved upstream or downstream of the stent.
  • Of note, there have been reports of coronary artery perforation[28][29] and target vessel revascularization[30][31] in patients with myocardial bridging during/following stent placement, respectively.
  • Stents placed in this position may be placed under torsional strain, extrinsic compression, and repeated flexion which may theoretically increase the risk of stent strut fracture.

Surgery

Surgery is limited to patients with symptoms that persist despite medical treatment.

1. CABG

Minimally invasive CABG with placement of a left internal mammary artery to the distal left anterior descending artery is one option.

2. Myectomy

Myectomy can be performed on the myocardium surrounding the coronary artery. The procedure involves surgical division (unroofing) of the coronary artery. Surgical unroofing of the myocardial bridge often results in clinical improvement.[19][32][33][34][35] Potential complications include right ventricular perforation and left ventricular aneurysm which can be avoided with the use of echocardiography to follow the course of the vessel.[36]

Surgery Contraindications

Cardiac surgery is not indicated for hypertrophic cardiomyopathy associated myocardial bridging, and medical therapy may provide adequate anti-ischemic therapy.[37]

References

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  2. 2.0 2.1 2.2 2.3 Möhlenkamp S, Hort W, Ge J, Erbel R (2002). "Update on myocardial bridging". Circulation. 106 (20): 2616–22. PMID 12427660. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  3. Reyman, HC. Disertatis de vasis cordis propiis. Bibl Anat. 1737; 2:366.
  4. 4.0 4.1 Faruqui AM, Maloy WC, Felner JM, Schlant RC, Logan WD, Symbas P (1978). "Symptomatic myocardial bridging of coronary artery". The American Journal of Cardiology. 41 (7): 1305–10. PMID 307341. Unknown parameter |month= ignored (help); |access-date= requires |url= (help)
  5. Morales AR, Romanelli R, Boucek RJ (1980). "The mural left anterior descending coronary artery, strenuous exercise and sudden death". Circulation. 62 (2): 230–7. PMID 7397963. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  6. Ishikawa Y, Akasaka Y, Suzuki K, Fujiwara M, Ogawa T, Yamazaki K, Niino H, Tanaka M, Ogata K, Morinaga S, Ebihara Y, Kawahara Y, Sugiura H, Takimoto T, Komatsu A, Shinagawa T, Taki K, Satoh H, Yamada K, Yanagida-Iida M, Shimokawa R, Shimada K, Nishimura C, Ito K, Ishii T (2009). "Anatomic properties of myocardial bridge predisposing to myocardial infarction". Circulation. 120 (5): 376–83. doi:10.1161/CIRCULATIONAHA.108.820720. PMID 19620504. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  7. Utuk O, Bilge A, Bayturan O, Tikiz H, Tavli T, Tezcan U (2010). "Thrombosis of a coronary artery related to the myocardial bridging". Heart, Lung & Circulation. 19 (8): 481–2. doi:10.1016/j.hlc.2009.08.006. PMID 19914131. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  8. Hostiuc S, Curca GC, Dermengiu D, Dermengiu S, Hostiuc M, Rusu MC (2011). "Morphological changes associated with hemodynamically significant myocardial bridges in sudden cardiac death". The Thoracic and Cardiovascular Surgeon. 59 (7): 393–8. doi:10.1055/s-0030-1270703. PMID 21448858. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  9. Husmann L, Nkoulou R, Wolfrum M, Kaufmann PA (2011). "Myocardial bridging causing infarction and ischaemia". European Heart Journal. 32 (7): 790. doi:10.1093/eurheartj/ehq423. PMID 21123275. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  10. Ge J, Jeremias A, Rupp A, Abels M, Baumgart D, Liu F, Haude M, Görge G, von Birgelen C, Sack S, Erbel R (1999). "New signs characteristic of myocardial bridging demonstrated by intracoronary ultrasound and Doppler". European Heart Journal. 20 (23): 1707–16. doi:10.1053/euhj.1999.1661. PMID 10562478. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  11. Ge J, Erbel R, Rupprecht HJ, Koch L, Kearney P, Görge G, Haude M, Meyer J (1994). "Comparison of intravascular ultrasound and angiography in the assessment of myocardial bridging". Circulation. 89 (4): 1725–32. PMID 8149538. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  12. Angelini P, Velasco JA, Flamm S (2002). "Coronary anomalies: incidence, pathophysiology, and clinical relevance". Circulation. 105 (20): 2449–54. PMID 12021235. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  13. Kramer JR, Kitazume H, Proudfit WL, Sones FM (1982). "Clinical significance of isolated coronary bridges: benign and frequent condition involving the left anterior descending artery". American Heart Journal. 103 (2): 283–8. PMID 7055058. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  14. 14.0 14.1 Sorajja P, Ommen SR, Nishimura RA, Gersh BJ, Tajik AJ, Holmes DR (2003). "Myocardial bridging in adult patients with hypertrophic cardiomyopathy". Journal of the American College of Cardiology. 42 (5): 889–94. PMID 12957438. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  15. Hongo Y, Tada H, Ito K, Yasumura Y, Miyatake K, Yamagishi M (1999). "Augmentation of vessel squeezing at coronary-myocardial bridge by nitroglycerin: study by quantitative coronary angiography and intravascular ultrasound". American Heart Journal. 138 (2 Pt 1): 345–50. PMID 10426850. Unknown parameter |month= ignored (help); |access-date= requires |url= (help)
  16. Iskandrian AE, Nallamothu N, Heo J (1996). "Nonatherosclerotic causes of myocardial ischemia". Journal of Nuclear Cardiology : Official Publication of the American Society of Nuclear Cardiology. 3 (5): 428–35. PMID 8902676. |access-date= requires |url= (help)
  17. La Grutta L, Runza G, Lo Re G, Galia M, Alaimo V, Grassedonio E, Bartolotta TV, Malagò R, Tedeschi C, Cademartiri F, De Maria M, Cardinale AE, Lagalla R, Midiri M (2009). "Prevalence of myocardial bridging and correlation with coronary atherosclerosis studied with 64-slice CT coronary angiography". La Radiologia Medica. 114 (7): 1024–36. doi:10.1007/s11547-009-0446-y. PMID 19697102. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  18. Hwang JH, Ko SM, Roh HG, Song MG, Shin JK, Chee HK, Kim JS (2010). "Myocardial bridging of the left anterior descending coronary artery: depiction rate and morphologic features by dual-source CT coronary angiography". Korean Journal of Radiology : Official Journal of the Korean Radiological Society. 11 (5): 514–21. doi:10.3348/kjr.2010.11.5.514. PMC 2930159. PMID 20808694. Retrieved 2012-07-01.
  19. 19.0 19.1 Yetman AT, McCrindle BW, MacDonald C, Freedom RM, Gow R (1998). "Myocardial bridging in children with hypertrophic cardiomyopathy--a risk factor for sudden death". The New England Journal of Medicine. 339 (17): 1201–9. doi:10.1056/NEJM199810223391704. PMID 9780340. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  20. Möhlenkamp S, Hort W, Ge J, Erbel R. Update on myocardial bridging.Circulation. 2002;106:2616 –2622.
  21. Erbel R, Rupprecht HJ, Ge J, Gerber T, Görge G, Meyer J. Coronary artery shape and flow changes induced by myocardial bridging. Echocardiography. 1993;1:71–77.]
  22. Rouleau JL, Chuck LH, Hollosi G, Kidd P, Sievers RE, Wikman Coffelt J, Parmley WW. Verapamil preserves myocardial contractility in the hereditary cardiomyopathy of the Syrian hamster. Circ Res. 1982;50:405–412.
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  24. Jeremias A, Haude M, Ge J, Görge G, Liu F, Konorza T, Erbel R. Emergency stent implantation in the area of extensive muscle bridging of the anterior interventricular ramus after post-interventional dissection [in German]. Z Kardiol. 1997;86:367–372.
  25. Ge J, Erbel R, Görge G, Haude M, Meyer J. High wall shear stress proximal to myocardial bridging and atherosclerosis: intracoronary ultrasound and pressure measurements. Br Heart J. 1995;73:462– 465.]
  26. Klues HG, Schwarz ER, vom Dahl J, Reffelmann T, Reul H, Potthast K, Schmitz C, Minartz J, Krebs W, Hanrath P (1997). "Disturbed intracoronary hemodynamics in myocardial bridging: early normalization by intracoronary stent placement". Circulation. 96 (9): 2905–13. PMID 9386156. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
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  28. Hering D, Horstkotte D, Schwimmbeck P, Piper C, Bilger J, Schultheiss HP (1997). "[Acute myocardial infarct caused by a muscle bridge of the anterior interventricular ramus: complicated course with vascular perforation after stent implantation]". Zeitschrift Für Kardiologie (in German). 86 (8): 630–8. PMID 9417754. Unknown parameter |month= ignored (help); |access-date= requires |url= (help)
  29. Zhang M, Kang WC, Moon CI, Han SH, Ahn TH, Shin EK (2010). "Coronary artery perforation following implantation of a drug-eluting stent rescued by deployment of a covered stent in symptomatic myocardial bridging". Korean Circulation Journal. 40 (3): 148–51. doi:10.4070/kcj.2010.40.3.148. PMC 2844983. PMID 20339502. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  30. Tsujita K, Maehara A, Mintz GS, Doi H, Kubo T, Castellanos C, Liu J, Yang J, Oviedo C, Franklin-Bond T, Sugirtharaj DD, Dangas GD, Lansky AJ, Stone GW, Moses JW, Leon MB, Mehran R (2009). "Impact of myocardial bridge on clinical outcome after coronary stent placement". The American Journal of Cardiology. 103 (10): 1344–8. doi:10.1016/j.amjcard.2009.01.340. PMID 19427426. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  31. Haager PK, Schwarz ER, vom Dahl J, Klues HG, Reffelmann T, Hanrath P (2000). "Long term angiographic and clinical follow up in patients with stent implantation for symptomatic myocardial bridging". Heart (British Cardiac Society). 84 (4): 403–8. PMC 1729426. PMID 10995410. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)
  32. Katznelson Y, Petchenko P, Knobel B, Cohen AJ, Kishon Y, Schachner A (1996). "Myocardial bridging: surgical technique and operative results". Military Medicine. 161 (4): 248–50. PMID 8935519. Unknown parameter |month= ignored (help); |access-date= requires |url= (help)
  33. Hill RC, Chitwood WR, Bashore TM, Sink JD, Cox JL, Wechsler AS (1981). "Coronary flow and regional function before and after supraarterial myotomy for myocardial bridging". The Annals of Thoracic Surgery. 31 (2): 176–81. PMID 7458489. Unknown parameter |month= ignored (help); |access-date= requires |url= (help)
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  36. Hiratzka LF, McPherson DD, Brandt B 3d, Lamberth WC Jr, Marcus ML, Kerber RE. Intraoperative high-frequency epicardial echocardiography in coronary revascularization: locating deeply embedded coronary arteries. Ann Thorac Surg 1986 Dec;42(6 Suppl):S9-11
  37. Mohiddin SA, Begley D, Shih J, Fananapazir L (2000). "Myocardial bridging does not predict sudden death in children with hypertrophic cardiomyopathy but is associated with more severe cardiac disease". Journal of the American College of Cardiology. 36 (7): 2270–8. PMID 11127472. Retrieved 2012-07-01. Unknown parameter |month= ignored (help)



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