Related Experiment Videos
[Evaluation of flow reserve in internal mammary artery in situ bypass]
M Zanchetta1, J Dalle Mule, C Di Mario
1Divisione di Cardiologia, Ospedale Civile, Cittadella, Padova.
Insights
Internal mammary artery grafts provide superior long-term outcomes for coronary artery bypass surgery compared to saphenous vein grafts. Studies show they maintain adequate blood flow during peak myocardial demand, reducing ischemia risk.
Area of Science:
- Cardiovascular Surgery
- Cardiac Surgery
- Vascular Surgery
Background:
- The internal mammary artery (IMA) is preferred for coronary artery bypass grafting (CABG) due to better long-term patency and survival rates than the saphenous vein (SVG).
- Concerns persist regarding potential inadequate IMA flow during peak myocardial demand.
Purpose of the Study:
- To investigate the adequacy of internal mammary artery blood flow during peak myocardial demand in patients undergoing coronary artery bypass surgery.
- To compare the efficacy of IMA grafts versus SVG conduits in preventing myocardial ischemia post-revascularization.
Main Methods:
- Evaluation of 18 patients undergoing left anterior descending artery bypass using IMA grafts.
- Post-operative assessment within 12 months included graded maximal stress testing, cardiac catheterization, and exercise thallium-201 scintigraphy.
Main Results:
- Internal mammary artery grafts demonstrated 100% patency, significantly higher than saphenous vein grafts (85%).
- Patients showed improved work capacity, rate-pressure product, and reduced angina and ECG abnormalities post-IMA grafting.
- Myocardial ischemia was significantly less frequent in IMA-supplied regions (7.4%) compared to SVG-supplied regions (31%) during stress testing.
Conclusions:
- Internal mammary artery grafting ensures adequate coronary blood flow at peak myocardial demand, as evidenced by low rates of ischemia on stress thallium scintigraphy.
- IMA grafts are associated with superior clinical outcomes and reduced ischemic events compared to saphenous vein grafts in coronary artery bypass surgery.
Abstract:
The internal mammary artery, when used as a conduit for coronary artery bypass, offers a better long-term patency and survival rate than the saphenous vein. However, concern exists that the flow through the internal mammary artery may be inadequate during periods of peak myocardial demand. This flow was investigated in 18 consecutive patients who were selected for coronary bypass of the left anterior descending artery using the internal mammary artery. All patients were evaluated post-operatively within 12 months by means of graded maximal stress test, cardiac catheterization and exercise thallium-201 scintigraphy. Significant improvement in work capacity, maximal rate-pressure product, effort angina and ECG abnormalities during exercise stress testing were observed following internal mammary artery myocardial revascularization. The patency rate for internal mammary artery grafts was 100% (vs 85% for vein grafts); during the followup period, occlusion of a saphenous vein bypass or development of a new stenosis in a native coronary artery was noted in five patients, and two patients were classified as having partial revascularization. Ischemia, demonstrated by perfusion deficits at peak stress which disappeared in the 3-hour delayed film, was documented in 7.4% (4/54) of the areas supplied by internal mammary artery grafts, compared to 31% (13/42) of the regions revascularized using saphenous vein conduits. Although this result was not statistically significant, a definite trend is suggested. We conclude that ischemia demonstrated by stress thallium scintigraphy in the post-operative period is uncommon when an internal mammary artery graft has been used. This suggests that adequate coronary flow exists at peak myocardial demand during exercise.