Teaching Case

Section

Cardiovascular

Case Type

Anatomy and Functional Imaging

Authors

Salman Javed Arain¹, Saima Khurshid¹, Ravi Adapala²

1. Department of Medicine, Wrexham Maelor Hospital, United Kingdom LL13 7TD

2. Department of Radiology, Wrexham Maelor Hospital, United Kingdom LL13 7TD

Patient

74 years, male

Categories

Area of Interest Cardiovascular system ; Imaging Technique CT, CT-Angiography ;

No Procedure ; Special Focus Ischaemia / Infarction ;

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Clinical History

A 74-year-old man presented to the A&E with two-hours history of non-radiating chest pain. Electrocardiogram (ECG) showed left bundle branch block and troponin-I was negative. Cardiovascular risk factors include age, gender and smoking. Considering ECG findings and risk factors, an echocardiogram and CT coronary angiogram were performed.

Differential Diagnosis List

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Coronary Artery Disease

GERD

Costochondritis

Myocardial bridging phenomenon involving LAD and RCA.

Imaging Findings

CT Coronary Angiogram:

Left Anterior Descending (LAD) - Soft plaque in the proximal vessel causing mild luminal stenosis. There is some positive remodelling of the vessel. Mixed morphology plaque in the mid vessel is seen causing mild luminal stenosis. Mid segment of LAD over a luminal length of approximately 13mms is seen dipping into the myocardium of the left ventricle giving rise to bridging with no stenosis. The distal vessel exhibits optimal opacification. The vessel wraps around the apex (Fig. 1).

Right Coronary Artery (RCA) - Dominant. Mixed morphology, predominantly calcified plaque in the proximal vessel causing mild luminal stenosis. Further predominantly soft plaque causing mild luminal stenosis just beyond this level. The mid vessel demonstrates an intramyocardial course giving rise to bridging over a luminal length of approximately 3.5 cm. The vessel is not narrowed in its intramyocardial course. Distal vessel demonstrates adequate contrast opacification (Fig. 2).

Discussion

Myocardial bridging phenomenon is one of the congenital cardiac diseases. In this condition, the coronary artery travels inside a tunnel surrounded and bridged by the myocardial muscle fibres [1]. The incidence of this phenomenon in autopsy studies ranges from 5-80% while angiographic incidence ranges from 0.5-12%. The commonest is the LAD bridging while RCA is very rare [2].

During systole, the coronary artery is squeezed by the contracting myocardium resulting in the reduction of blood supply. These hemodynamic changes can present in the form of acute coronary symptoms [3], rhythm disturbance [4,5] or sudden deaths [6].

There is also a high risk of developing atherosclerosis in such coronary arteries because of the constant stress faced by the proximal segment of vessel during each cardiac cycle [7].

This condition was first described during an autopsy in 1737 by Reyman[8] and angiographically by Portsman[9]. In the modern medicine, there are many non-invasive modalities to confirm the diagnosis, for example, CT coronary angiogram[10], Intracoronary Doppler[11], Fractional Flow Reserve[12] and intravascular ultrasound[13].

Despite very good understanding of the disease, the treatment options are very limited. Medical treatment includes beta-blocker and calcium channel blocker[14] while myotomy remains the second line[15]. Coronary Angiogram and stenting is not the treatment of choice and ends up with lethal complications[16].

Myocardial Bridging was an incidental finding in our patient as no significant stenosis was seen in the bridged segments during the cardiac cycles. CTCA has revealed triple vessel disease which was Later confirmed on an elective Angiogram.

This phenomenon is a rare differential that should not be ignored in any case of atypical chest pain.

Written informed patient consent for publication has been obtained.

References

[1] Angelini P, Velasco JA, Flamm S. Coronary anomalies: incidence, pathophysiology, and clinical relevance. Circulation. 2002 May 21;105(20):2449-54.

[2] Nguyen TH, Burnside PR, Dieter RS, Nanjundappa A. Right coronary artery distribution of myocardial bridging: an unusual case presenting with ST-Elevation myocardial infarction. Texas Heart Institute Journal. 2007;34(4):489.

[3] Rossi L, Dander B, Nidasio GP, Arbustini E, Paris B, Vassanelli C, Buonanno C, Poppi A. Myocardial bridges and ischemic heart disease. European heart journal. 1980 Aug 1;1(4):239-45.

[4] Feld H, Guadanino V, Hollander G, Greengart A, Lichstein E, Shani J. Exercise-induced ventricular tachycardia in association with a myocardial bridge. Chest. 1991 May 1;99(5):1295-6.

[5] Den Dulk K, Brugada P, Braat S, Heddle B, Wellens HJ. Myocardial bridging as a cause of paroxysmal atrioventricular block. Journal of the American College of Cardiology. 1983 Mar 1;1(3):965-9.

[6] Cutler D, Wallace JM. Myocardial bridging in a young patient with sudden death. Clinical cardiology. 1997 Jun;20(6):581-3.

[7] Ge J, Jeremias A, Rupp A, Abels M, Baumgart D, Liu F, Haude M, Görge G, Von Birgelen C, Sack S, Erbel R. New signs characteristic of myocardial bridging demonstrated by intracoronary ultrasound and Doppler. European Heart Journal. 1999 Dec 1;20(23):1707-16.

[8] Reyman HC. Dissertatio de vasis cordis propriis. Bibl Anat. 1737;2:359-78.

[9] Porstmann W, Iwig J. Die intramurale koronarie im angiogramm. InRöFo-Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren 1960 Feb (Vol. 92, No. 02, pp. 129-133). © Georg Thieme Verlag KG Stuttgart· New York.

[10] Konen E, Goitein O, Sternik L, Eshet Y, Shemesh J, Di Segni E. The prevalence and anatomical patterns of intramuscular coronary arteries: a coronary computed tomography angiographic study. Journal of the American College of Cardiology. 2007 Feb 6;49(5):587-93.

[11] Schwarz ER, Klues HG, Vom Dahl J, Klein I, Krebs W, Hanrath P. Functional characteristics of myocardial bridging: a combined angiographic and intracoronary Doppler flow study. European heart journal. 1997 Mar 1;18(3):434-42.

[12] Escaned J, Cortés J, Flores A, Goicolea J, Alfonso F, Hernández R, Fernández-Ortiz A, Sabaté M, Bañuelos C, Macaya C. Importance of diastolic fractional flow reserve and dobutamine challenge in physiologic assessment of myocardial bridging. Journal of the American College of Cardiology. 2003 Jul 16;42(2):226-33.

[13] Ge J, Jeremias A, Rupp A, Abels M, Baumgart D, Liu F, Haude M, Görge G, Von Birgelen C, Sack S, Erbel R. New signs characteristic of myocardial bridging demonstrated by intracoronary ultrasound and Doppler. European Heart Journal. 1999 Dec 1;20(23):1707-16.

[14] Möhlenkamp S, Hort W, Ge J, Erbel R. Update on myocardial bridging. Circulation. 2002 Nov 12;106(20):2616-22.

[15] Betriu A, Tubau J, Sanz G, Magriña J, Navarro-Lopez F. Relief of angina by periarterial muscle resection of myocardial bridges. American heart journal. 1980 Aug 1;100(2):223-6.

[16] Li W, Li Y, Sheng L, Gong Y. Myocardial bridge: Is the risk of perforation increased?. Canadian Journal of Cardiology. 2008 Nov 1;24(11):e80-1.

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