Comparison of coronary hemodynamics in patients with internal mammary artery and saphenous vein coronary artery bypass grafts: A noninvasive approach using combined two-dimensional and Doppler echocardiography

Abstract

Blood flow in bypass grafts and recipient left anterior descending coronary arteries was evaluated with combined two-dimensional and Doppler echocardiography in 15 patients with an internal mammary artery graft and in 24 patients with a saphenous vein graft. Comparative studies of coronary hemodynamics were also performed regarding these two different grafting techniques. The graft vessel was detected in 11 (79%) of 14 patients with an internal mammary artery graft and in 20 (87%) of 23 with a saphenous vein graft. The recipient left anterior descending coronary artery was detected in 10 (67%) of the former group and 17 (71%) of the latter. The blood flow patterns obtained were generally biphasic, consisting of systolic and diastolic phases with higher velocity during diastole. The maximal diastolic flow velocity in internal mammary artery grafts was much higher than that in saphenous vein grafts. In patients with an internal mammary artery graft, the flow pattern characteristics within the recipient coronary artery were quite similar to those within the arterial graft, and flow velocities within the recipient coronary artery and the arterial graft were quantitatively almost identical. This outcome may contribute to the long-term patency seen in internal mammary artery grafts. On the other hand, the flow velocity in saphenous vein grafts was fairly low throughout the cardiac cycle. Flow velocity in the recipient coronary artery in patients with a saphenous vein graft was accelerated only in early diastole. As a result, the recipient coronary artery flow pattern and velocity differed substantially from those in the saphenous vein graft.(ABSTRACT TRUNCATED AT 250 WORDS)

Morphologic and functional evaluation of coronary artery bypass conduits

“…Graft flow velocity was characterized by a biphasic pattern, with one peak in systole and a second peak in diastole. Similar findings have been obtained using invasive Doppler guidewire approaches and transthoracic Doppler echocardiography (7,14). MRI-assessed volume flow of grafts with three sequential anastomoses significantly differed from single grafts.…”

“…Two-dimensional (2D) Doppler echocardiography is restricted to evaluation of grafts placed on the left anterior descending coronary artery (14)(15)(16). A unique feature of MRI is that, in addition to standard imaging of morphology, blood flow can be quantified within the grafts.…”

Long-term Morphofunctional Remodeling of Internal Thoracic Artery Grafts

“…Indeed, in situ LITA is a resistance conduit with a prevalent systolic flow, but after CABG it is attached to a low resistance vascular bed characterized by prevalent diastolic flow. 17 The increased flow 18 leads to higher peak and time-averaged flow velocities 17 and thus to higher shear stress, known to favor NO production. 19 Moreover, a high intrinsic production of NO in the LITA has already been described.…”

Usefulness of High-Frequency Transthoracic Doppler Echocardiography in Noninvasive Diagnosis of the Left Internal Thoracic Artery Graft Stenosis at the Anastomosis

“…Pulsed Doppler echocardiography was first reported in the 1970s as a useful method of assessing the patency of saphenous vein coronary bypass grafts, 18,19 and other reports [1][2][3] demonstrated that LITA graft flow could be detected by transthoracic echocardiography with a parasternal or supraclavicular approach, although the detection rate was unsatisfactory. Recent studies have demonstrated that high-frequency transthoracic echocardiography can detect significant stenosis of the LITA graft by evaluating the ratio of the diastolic-to-systolic velocity or the diastolic fraction of the LITA graft flow; [4][5][6] however, the flow pattern is influenced by other factors, such as the site of measurement within the LITA graft, the persistence of the branches of the LITA, the degree of stenosis in the native coronary artery and the regional wall motion of the left ventricle.…”