Combined PTCA and microcoil embolization of a left internal mammary artery graft

Physiologic Functional Evaluation of Left Internal Mammary Artery Graft to Left Anterior Descending Coronary Artery Steal due to Unligated First Thoracic Branch in a Case of Refractory Angina

Unligated side branches of the left internal mammary artery (LIMA) have been described in the literature as a cause of coronary steal resulting in angina. Despite a number of studies reporting successful side branch embolization to relieve symptoms, this phenomenon remains controversial. Hemodynamic evidence of coronary steal using angiographic and intravascular Doppler techniques has been supported by some and rejected by others. In this case study using an intracoronary Doppler wire with adenosine, we demonstrate that a trial occlusion of the LIMA thoracic side branch with selective balloon inflation can confirm physiologic significant steal and whether coil embolization of the side branch is indicated.

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.

Transbrachial Coil Occlusion of the Large Branch of an Internal Mammary Artery Coronary Graft

Percutaneous transbrachial insertion of two complex coils into the intercostal branch of the left internal mammary artery resulted in the relief of severe angina in a 45-year-old man who had coronary artery bypass surgery 2 years before. The diagnosis of coronary artery steal was made clinically. This case illustrates the importance of recognizing coronary steal in patients who redevelop angina after coronary artery surgery with the use of an incompletely prepared left internal mammary artery as a conduit. Brachial or radial artery should be preferred to reach left internal mammary artery (LIMA) for cannulation easily. The preoperative angiographic imaging of LIMA is important to detect the side branches and their sizes. The patient was treated without the need for further surgery.

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.

Functional evaluation of steal by unligated first intercostal branch before transcatheter embolization in recurrent angina after a LIMA-LAD graft

Unligated side branches of the left internal mammary artery (LIMA) have been indicated as a cause of coronary steal resulting in postoperative angina. Although a number of studies have reported successful embolization of the side branches to relieve angina, this phenomenon is still controversial and it has been either emphasized or rejected in studies that attempted to obtain hemodynamic evidence of the steal using angiographic and intravascular Doppler techniques. In this case study, we tried to reproduce physiological decrease in the muscular and coronary beds as it could occur during activity. Our results, using an intracoronary Doppler wire with adenosine combined with forced ventilation, showed that a trial occlusion of the LIMA side branch with a balloon technique can demonstrate whether the flow through the LIMA would increase after embolization of the side branch.

Patent side branches do not affect coronary blood flow in internal thoracic artery-left anterior descending anastomosis: an experimental study

BACKGROUND

It has been reported that large side branches of internal thoracic artery grafts may steal flow from the coronary circulation. Material an.

METHODS

To assess the importance of the side branches, we measured the proximal and distal flow and pressures (mean subclavian artery pressure and mean arterial anastomotic pressure) at baseline and during infusion of adenosine (0.5 mg/kg/min) in 10 Landrace pigs in which an internal thoracic artery-left anterior descending anastomosis was constructed without interruption of the side branches. The difference between proximal and distal flow was considered to represent the blood flow of the internal thoracic artery side branches. Measurements were then repeated after surgical occlusion of all the side branches.

RESULTS

At baseline, blood flow of the side branches represented 18% of the total flow in the proximal internal thoracic artery, and this percentage remained constant under the infusion of adenosine, which caused a 220% increase of the cardiac index and a 368% increase of the proximal flow. The infusion reduced the gradient along the left internal thoracic artery (mean subclavian artery pressure-mean arterial anastomotic pressure) from 15 to 10 mm Hg (P =.02) as the result of a lower mean subclavian artery pressure, although the mean arterial anastomotic pressure remained constant. Interruption of all the side branches resulted in a small and not significant increase in distal flow even after adenosine infusion.

CONCLUSION

These observations suggest that blood flow in the side branches is minimal either at baseline and under combined systemic and coronary vasodilation. Clinically significant flow steal from the coronary circulation to the internal thoracic artery side branches seems then unlikely.

Steal phenomenon from mammary side branches: when does it occur?

BACKGROUND

The hemodynamic significance of patent mammary graft side branches is still controversial. This study was designed to evaluate the potential for flow steal of patent mammary side branches in different hemodynamic conditions.

METHODS

Echo-Doppler measurement of mammary graft flow was performed at rest and after dipyridamole-induced coronary vasodilatation in 10 patients with angiographic demonstration of evident mammary graft side branches (study group) and in 10 matched control patients (control group). Concomitant thallium-201 myocardial scintigraphy was performed to assess the adequacy of mammary flow to the myocardial oxygen demand. Patients of the study group were also submitted to flow evaluation in condition of selective muscular or combined systemic and coronary relaxation.

RESULTS

No difference in mammary flow and adequacy to myocardial oxygen demand was detected between patients of the study and control groups both at rest and after dipyridamole infusion. In patients with patent side branches the systolic-to-diastolic flow ratio was maintained in case of combined coronary and peripheral vasodilatation, whereas selective muscular relaxation led to an increase in the systolic and a reduction in the diastolic flow.

CONCLUSIONS

Flow steal from patent mammary graft side branches is possible only in case of selective muscular vasodilatation. As this situation is unlikely to occur in the clinical setting, the potential for flow steal of mammary side branches in cardiac surgery patients seems to be minimal.

[Refractory angina caused by steal phenomenon in internal mammary artery resolved with embolization]

We report a patient with refractory angina in the postoperative period of a coronary artery bypass grafting. Ischemia was due to a large side branch of the left internal mammary artery causing steal phenomenon that was treated with transcatheter coil embolization.

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.

Novel technique for coil embolization of intercostal branch of internal mammary artery graft

Coronary artery steal resulting from a large unligated intercostal or pericardial side branch of the internal mammary artery graft causing postoperative angina has been previously described. Transcatheter coil occlusion of internal mammary artery side branch has successfully been performed to treat coronary steal syndrome. Unsuccessful deployment of the microcoils can be due to inadequate guiding support in the LIMA or prolapse of the delivery catheter in the side branch. We report a new approach for the precise deployment of coils in the side branch of a LIMA graft, when inadequate guiding support is present.

Transbrachial coil occlusion of the first intercostal branch of an internal mammary artery bypass graft for angina

Percutaneous transbrachial insertion of a metallic coil into the first intercostal branch of the left internal mammary artery resulted in resolution of severe angina in a 60-year-old man who had coronary artery bypass surgery 14 years previously. The diagnosis of coronary artery steal was made clinically. This case illustrates the importance of recognising coronary steal in patients who redevelop angina after coronary artery surgery with the use of an incompletely prepared left internal mammary artery as a conduit. The diagnosis can be made clinically and the condition treated without the need for further surgery.

Repeat embolization of the side branch of the internal mammary artery graft by gelatin sponge particles and micro coils

The internal mammary artery (IMA) is increasingly used as a coronary bypass conduit because of better long-term patency and improved prognosis as compared with venous grafts. Previous investigators have suggested that the "steal" of blood flow of the IMA graft via the subclavian artery or a persistent large side branch of the graft may lead to its thinning. However, only a few reports have described the embolization of a large side branch using a transcatheter procedure. We present a case of repeated embolization of a large lateral costal side branch of the left internal mammary arterial graft applying gelatin sponge particles and micro coils, as well as angioplasty to the graft conduit, with resulting easing of chest pain.

Microcoil embolization of large intercostal branches of internal mammary artery grafts

Coronary artery steal via a large unligated intercoastal side-branch of the internal mammary artery graft has been previously described in two case reports. We report a series of 7 patients with post-operative angina in whom microcoil embolization of such branch was performed. In 5 patients in whom complete occlusion of the branch was achieved, anginal symptoms were relieved; in contrast the 2 patients with persistent flow through the intercostal branch remained symptomatic despite all their grafts being widely patent. We conclude that large unligated intercostal branches of the IMA graft may be related with post-operative angina and their embolization is a simple, safe, and effective procedure.