Myocardial bridging

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Coronary Angiography


General Principles

Historical Perspective
Appropriate Use Criteria for Revascularization
Film Quality

Anatomy & Projection Angles

Normal Anatomy

Coronary arteries
Right System
Left System
Left Main
Left Anterior Descending
Median Ramus

Anatomic Variants

Separate Ostia
Anomalous Origins
Case Example

Projection Angles

Standard Views
Left Coronary Artery
Right Coronary Artery

Epicardial Flow & Myocardial Perfusion

Epicardial Flow

TIMI Frame Count
TIMI Flow Grade
TIMI Grade 0 Flow
TIMI Grade 1 Flow
TIMI Grade 2 Flow
TIMI Grade 3 Flow
TIMI Grade 4 Flow
Pulsatile Flow

Myocardial Perfusion

TIMI Myocardial Perfusion Grade
TMP Grade 0
TMP Grade 0.5
TMP Grade 1
TMP Grade 2
TMP Grade 3

Lesion Complexity

ACC/AHA Lesion-Specific Classification of the Primary Target Stenosis

Preprocedural Lesion Morphology

Intimal Flap
Sawtooth Pattern
Ostial location
Proximal tortuosity
Degenerated SVG
Total occlusion
Coronary Artery Thrombus
TIMI Thrombus Grade
TIMI Thrombus Grade 0
TIMI Thrombus Grade 1
TIMI Thrombus Grade 2
TIMI Thrombus Grade 3
TIMI Thrombus Grade 4
TIMI Thrombus Grade 5
TIMI Thrombus Grade 6

Lesion Morphology

Quantitative Coronary Angiography
Definitions of Preprocedural Lesion Morphology
Irregular Lesion
Disease Extent
Arterial Foreshortening
Infarct Related Artery
Degenerated SVG

Left ventriculography

Quantification of LV Function
Quantification of Mitral Regurgitation

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


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]



There are two basic morphologic variants:


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 of myocardial bridging include the following:


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


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


Medical Treatment


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


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]


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