Case Author(s): Rusty Roberts, M.D., Henry Royal, M.D., and Robert Gropler, M.D. , . Rating: #D3, #Q3

Diagnosis: Right coronary artery occlusion with masked left coronary and circumflex artery disease

Brief history:

60 year old man with exertional chest pain.


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Coronary angiography. View Angio cine #1 in AVI format. View Angio cine #2 in AVI format.

Full history/Diagnosis is available below

Diagnosis: Right coronary artery occlusion with masked left coronary and circumflex artery disease

Full history:

60 year old man with exertional chest pain. He has cardiac risk factors of diabetes, hypertension, and family history of coronary disease. He has an early R waves on the resting EKG.


2.5 mCi Tl-201 chloride i.v. and 21.3 mCi Tc-99m sestamibi i.v.


Myocardial Perfusion:

There is a large completely reversible perfusion defect of moderate severity in the inferior wall. Gated post-stress images demonstrate normal left ventricular wall thickening. There is mild to moderate left ventricular enlargement, and the left ventricular ejection fraction is 50%.


1. Left main artery: The left main coronary artery has 60 +/- 10% diffuse narrowing in the LAO cranial view, but the narrowing in the LAO caudal view is less than 50%. There is a small ledge near the ostium of the left main coronary artery which prevents the catheter from advancing further into the vessel.

2. Left anterior descending artery: The left anterior descending coronary artery has a 70% narrowing in its proximal portion in the caudal views. There is diffuse 40 +/- 10% narrowing throughout the proximal and mid vessel. Distal to the small second diagonal branch there is a 60% narrowing. The first diagonal branch has 80% proximal narrowing. The moderate sized intermediate coronary artery has diffuse 50-60% proximal narrowing.

3. Circumflex coronary artery: This dominant circumflex coronary artery has 50-60% proximal narrowing, 70-80% narrowing involving the origin of a superior ramus in a large LPL 1 branch. The inferior ramus is large. Distal to this LPL 1 branch there is a 60% narrowing of the circumflex coronary artery which compromises four distal branches. The distal circumflex coronary artery provides collateral blood flow to the right coronary artery.

4. Right coronary artery (not shown): The right coronary artery is occluded proximally before the takeoff of any major branches. This is a non-dominant right coronary artery which is collateralized from the circumflex coronary artery.


The myocardial perfusion exam revealed ischemia in the right coronary artery distribution. No wall motion abnormalities were seen and function was preserved. Upon catheterization severe three vessel disease was found with complete occlusion of the RCA. The circumflex artery reconstituted the RCA. The atherosclerotic disease affecting the left coronary artery and circumflex branch was essentially masked by the severe RCA disease. This caused the myocardial perfusion images to be falsely negative in the distribution of the less affected LCA and circumflex arteries. Of particular note, the left ventricle does not exhibit transient ischemic dilation (TID) by visualization or according to the calculations. TID is a nonspecific sign of multivessel disease.

This type of presentation may also be seen with "balanced" 3 vessel disease causing no significant defects because the entire myocardium is involved relatively equally.


A four vessel coronary artery bypass was performed 3 days after the myocardial perfusion exam and 1 day after the coronary angiography consisting of left internal mammary artery to left anterior descending, radial artery to obtuse marginal-2, saphenous vein graft to first diagonal, and saphenous vein graft to posterior descending artery.

Major teaching point(s):

Myocardial images may not identify all the abnormalities in multivessel disease because, as in this case, only the severest location may be visualized or an image of balanced disease may be seen without defects.

ACR Codes and Keywords:

References and General Discussion of Myocardial Imaging (Anatomic field:Heart and Great Vessels, Category:Organ specific)

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Case number: mi031

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