Persistence of Mammary Artery Branches and Blood Supply to the Left Anterior Descending Artery

Does a LIMA side branch ever need occlusion? (Why I don't think so)

“…This noncompetitive physiology was demonstrated by measuring flow through a large pectoralis artery branch and the patent IMA at rest and during hyperemia [5]. In further support of the nonsteal phenomenon, Luise et al [6] noted no differences in LIMA blood flow when comparing groups with and without intact side branches. Abhyankar et al [7] also reported that angioplasty balloon occlusion of a large LIMA side branch did not alter measured LIMA flow to the left anterior descending artery.…”

“…This speculation on presumed physiology is not in concert with the measured coronary blood flow responses in the LIMA and its associated chest-wall branches [5][6][7]. From direct evidence, it appears that diversion of flow cannot result from the phasic nature of two systems alone without a pathologic stenosis interposed in the circuit [20].…”

Transthoracic Doppler echocardiography of the left internal mammary artery graft

“…In the study of Madaric et al [26] it was shown that a ratio PSV/PDV< 2 yielded optimal accuracy to detect the absence of LIMA bypass dysfunction with a negative predictive value of 95%. Its positive predictive value was only 52.4%.…”

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

“…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. 6,[11][12][13][14] In addition, the diastolic fraction of the LITA graft flow cannot distinguish mild or intermediate graft stenosis. Measuring flow reserve after drug administration or exercise is a useful method of evaluating the LITA graft stenosis that could not be detected by the LITA graft flow pattern at rest, but measuring the flow reserve may complicate a routine examination.…”