AbstractIn preparation for coronary bypass surgery, digital subtraction angiography (DSA) was used to assess the caliber of the left and right internal mammary arteries and to exclude stenoses of their feeding arteries. In 100 patients (86 males, mean age 56 ± 9 years) DSA was performed with a Siemens Digitron 2 device. A frontal projection was used in 18 patients, and a 10–20 degree right anterior oblique projection was used in 82 patients. The flow was 10 to 25 ml/sec; 20 ml was injected in 45 patients, 30 ml in 41, 40 ml in 5, 50ml in 8, and 60 ml in 1 patient, Judged on the proximal third, visualization of the left and the right internal mammary artery was good in 80 and 72, fair in 17 and 20, and bad in 3 and 8 arteries, respectively. The diameter (mm) was 2.7 ± 0.4 (range 1.8–3.4) and 2.7 ± 0.3 (range 2.0–3.5), and visible length (cm) was 8 ± 5 (range 1–24) and 9 ± 4 (range 2–22) for the two arteries, respectively. The 10–20 degree right anterior oblique view separated the left internal mammary artery better from the descending aorta than the frontal view. In more pronounced right anterior oblique views the ascending aorta interfered with the right internal mammary artery. The quality was not different with 20 ml or 30 ml injections. The feeding arteries could not be assessed in 4 patients. One left subclavian artery was found occluded at the orifice. Incidentally, 2 distal right subclavian stenoses and 2 carotid stenoses were detected. In conclusion, DSA with 20 ml (10 ml/sec) of contrast medium, injected into the ascending aorta in a 15 degree right anterior oblique view, sufficiently visualizes the internal mammary arteries and their feeding vessels before bypass surgery in most patients. Any catheter inserted for coronary or left ventricular angiogr