Transcatheter treatment of angina after coronary surgery due to concomitant internal mammary steal and right coronary artery stenosis: a need for staging

Transcatheter occlusion of a large intercostal side-branch of left internal mammary artery bypass with detachable platinum coils

Intercostal branches of the internal mammary artery (IMA) are usually tied off during IMA-bypass surgery. Some side-branches may be missed, however, due to anatomical variants or during minimal invasive procedures with limitation of the surgeon's ability to ligate proximal branches. There are a number of reports in the literature describing interventional closure of side-branches using Gianturco coils. Following embolization or malposition, however, these coils may be extremely difficult to retrieve from coronary arteries. We report about interventional embolization of a IMA side-branch with detachable micro-coils in a patient with symptomatic coronary steal. Detachable coils are safer than Gianturco coils and are an effective method to abolish symptomatic coronary steal due to unligated intercostal branches of the IMA graft.

Fallacy of thoracic side-branch steal from the internal mammary artery: Analysis of left internal mammary artery coronary flow during thoracic side-branch occlusion with pharmacologic and exercise-induced hyperemia

In some patients, myocardial ischemia after coronary artery bypass graft surgery has been attributed to a coronary steal phenomenon through a thoracic side branch originating from the left internal mammary artery (LIMA), even in the absence of subclavian or LIMA stenosis. To demonstrate that coronary flow through the LIMA is unchanged by occlusion of a LIMA side branch, we examined LIMA coronary flow velocity measurements (0.014" Doppler flow wire) in three patients at rest, during adenosine hyperemia, and again during hyperemia induced by left arm exercise before and again after the balloon occlusion of the thoracic side branch. For the three patients, no significant changes in resting or hyperemic flow were noted due to side-branch occlusion. Before side-branch occlusion, pharmacologic intra-arterial (adenosine) coronary flow reserve (hyperemic-to-basal flow velocity ratio) was 2.6, 1.5, and 3.2 and exercise flow reserve was 2.1, 1.3, and 1.2, respectively. After side-branch occlusion, pharmacologic coronary flow reserve was 2.5, 1.8, and 2.7 with exercise flow reserve of 1.8, 1.1, and 1.3, respectively. Under most ordinary circumstances, thoracic side-branch steal does not exist and that side-branch occlusion does not alter LIMA flow at rest or during pharmacologic or exercise-induced hyperemia. These data further suggest that a demonstration of the physiologic value of side-branch occlusion should precede surgical or percutaneous interruption of the thoracic artery in such patients.

Doppler features of occlusion of the internal thoracic artery due to preoperative branch embolization

A 61-year-old male was referred to the surgical ward by cardiologists because of a diagnosis of unstable angina with 3-vessel disease. On preoperative left internal thoracic arteriography, a large first intercostal branch was found at the proximal portion. Selective arterial embolization of the branch of the left internal thoracic artery (LITA) was carried out preoperatively. At 2 days after embolization, the Doppler peak flow velocity and diameter of the LITA were increased and enlarged compared with before the procedure. However, a large reverse wave following after the first systolic peak flow of the LITA was newly detected after embolization. Upon operation, the LITA was found to be occluded at the 2nd intercostal space due to thrombus formation. Therefore, the right internal thoracic artery was anastomosed to the left anterior descending artery and coronary reversed saphenous vein grafts were joined to segment 4PD of the right coronary artery. The postoperative course was uneventful. There has been no previous report of an LITA branch being embolized preoperatively. It was possible to diagnose the graft problem by detecting the altered Doppler wave form of the LITA.

Coronary steal by IMA bypass graft side-branches: a novel therapeutic use of a new detachable embolization coil

Coronary artery steal syndromes following coronary artery bypass grafting (CAB) may occur as a result of the presence of large side-branches arising from the internal mammary artery (IMA). We report the first successful deployment of a new detachable vascular embolization coil device to occlude the IMA side-branches in two patients. Optimal positioning is easily obtained with the unique operator-controlled, safety-release protected mechanism of this device. Complete retraction is possible, with safe and efficient removal of the coil even after deployment. This feature was appreciated during one procedure in which the initially selected coil was found to be oversized, requiring immediate removal. Acute thrombo-occlusion of the IMA side-branches in both patients was observed. We conclude that IMA bypass graft side-branches causing coronary steal can be safely and effectively occluded using this new technique. However, due to observed delayed partial recanalization noted on distant follow-up angiography, we recommend placement of multiple coils at the time of initial embolization.