The following movie illustrates a patient with multiple grafts: a LIMA graft to the LAD, a saphenous vein jump graft to two obtuse marginal arteries, and a saphenous vein graft to the posterior descending artery.
(Click on arrow to start movie)
By-pass grafts, especially saphenous vein grafts, are easier to image and assess by CT angiography than coronary arteries for two reasons: they are less mobile and they are larger.
This has been confirmed by several studies comparing catheterization and CT angiographic data, with values for sensitivity, specificity, positive predictive value, and negative predictive value all ranging from 90-100%, results which are distinctly superior to those for coronary stenoses.
Any patient with new chest pain who is at risk of graft failure is an excellent candidate for CT angiography.
This patient is a 64 year old man with three prior grafts who had undergone catheterization and angiography one year previously because of chest pain and was found to have a patent LIMA/LAD graft and patent SVGs to the diagonal and obtuse marginal arteries. He now presents with recurrent chest pain. A CT angiogram revealed the following images.
This single VRT image shows that all three grafts are patent. Of special note is the size mismatch of the SVG to the diagonal artery which fills primarily retrograde. SImilar findings had been noted at the prior catheterization.
A curvilinear MPR image shows the full course of the LIMA and the excellent anastamosis of the LIMA graft at the LAD with a widely patent distal vessel.
An enlarged curvilinear MPR image shows the SVG-Diagonal anastamosis.
A similar curvilinear MPR image shows the SVG-OM anastamosis.
Other images showed the occluded but collateralized right coronary artery to also be patent. CT coronary angiography saved this patient another catheterization.
The VRT image below is from a patient with post-operative chest pain whose LIMA graft was occluded. The upper thick arrow shows origin of the LIMA from the subclavian artery. The lower thick arrow shows the approximate site of the original LAD anastamosis. The multiple thin arrows show metal clips along the course of the occluded graft.