Bifurcation Balloon for Left Main Shock Syndrome: Facilitating the Simultaneous Percutaneous Reperfusion of the LAD and Circumfl

Acute thrombosis of the unprotected left main coronary artery (LMCA) produces cardiogenic shock (CS), or left main shock syndrome, in the majority of affected patients.^1,2 The prognosis of the subset of patients that have complete (TIMI 0) occlusion is dire, with up to 100% mortality.¹ Treatment needs to be prompt and aggressive, with an emphasis on the rapid restoration of flow in order to optimize cardiac salvage. Bifurcation systems for angioplasty are currently under development and have had reasonable success rates reported in the literature.^3,4 The Avion bifurcation RX2 balloon (Invatec, Srl, Roncadelle, Italy) is an example of such a recently developed, dedicated bifurcation system (Figure 1). We describe a case in which this novel technology was used to treat a completely occluded carina of the LMCA in a patient who had undergone recent percutaneous coronary intervention (PCI) to his proximal left anterior descending (LAD) and proximal circumflex (Cx) arteries. The use of a bifurcation balloon produced simultaneous and rapid restoration of flow in both vessels with a single inflation and successfully provided a bridge to surgery. Case Report. A 56-year-old male was transferred to our catheterization laboratory from another hospital because of cardiogenic shock and widespread ST-elevation. He had received ostial LAD and Cx stents at another institution 2 weeks prior to admission. He had been prescribed daily treatment with aspirin and clopidogrel, but there was no information regarding compliance. Upon arrival to the catheterization suite, his blood pressure was 66/40 mmHg and his pulse rate was 50 beats/minute. His radial arteries were impalpable so he was catheterized via the right femoral artery with a 6 Fr JL 3.5 Zuma guiding catheter (Medtronic, Inc., Minneapolis, Minnesota), revealing a distal LMS (Figure 2) occlusion with stent thrombosis in both stents. Two angioplasty wires (Galeo Hydro, Biotronik, Berlin, Germany) were quickly placed in the distal LAD and Cx. A 3.0/2.5 x 20 mm Avion bifurcation RX2 balloon was successfully inflated at 10 atm at the LMCA carina for 20 seconds (Figure 3A). This restored full TIMI 3 flow in both the LAD and Cx (Figure 3B). The time from visualization of the LMCA occlusion to balloon inflation was no more then 5 minutes. A filling defect suggestive of thrombus was visible in the proximal LAD. Thrombus aspiration with an Export Aspiration Catheter (Medtronic) improved this (Figure 4). An intra-aortic balloon pump (IABP) was inserted. His blood pressure rose to 90/60 mmHg and at this stage, a cardiothoracic surgeon had arrived. As the patient’s hemodynamic status had improved and TIMI 3 flow had been restored, further management was considered. PCI was felt to be technically possible, but there were concerns about possible residual thrombus encouraging thrombogenicity, which might be further exacerbated by more layers, and a greater surface area of stent metal. These factors, together with the lack of history regarding compliance with aspirin and clopidogrel, were felt to threaten the best chance of a good long-term PCI outcome. He proceeded to coronary artery bypass graft surgery (CABG) in which 2 saphenous vein grafts were used, a jump graft to the LAD and then the diagonal, and a graft to the obtuse marginal. Postoperatively, the patient remained hemodynamically stable in the intensive care unit with a low dose of inotropes. His CK-MB peaked at a value of 307 µg/l. Two days later, he was extubated, the IABP was removed and he was transferred to the cardiothoracic ward. Unfortunately, during the early hours of the following day, he rapidly developed acute dyspnea and hypotension without a pathological rhythm or ST shift and, despite the rapid reinstitution of inotropes, he could not be resuscitated. His family did not consent to a post-mortem examination for religious reasons. Discussion Acute thrombosis of the LMCA produces ischemia in a large left ventricular territory. LMCA infarction leads to CS in over 70% of cases,^1,5 and current data from the SHOCK trial⁶ indicate that revascularization is associated with an improved 6-month outcome in cases of CS due to acute myocardial infarction (AMI). This is compatible with the premise that prompt restoration of flow is imperative to achieve as much myocardial salvage as possible. The diagnosis of LMCA involvement is made upon angiography. Despite the use of a variety of reperfusion strategies for LMCA occlusion, patients with CS due to LMCA occlusion continue to have a particularly high mortality rate. In our patient, the use of the bifurcation balloon restored TIMI 3 flow within 5 minutes of visualization. This system consists of a single hypotube that splits distally into two separate shafts, each of which has a balloon (Figure 1). Both balloons have radiopaque end-markers, with the smaller balloon also being equipped with a central marker. As the two balloons are interconnected via a common shaft, preparation before introduction is similar to that of a single balloon. Suction of the system by hand to remove air is followed by attachment of the single hub to a single indeflater filled with 50:50 contrast-water mixture as per normal procedure. Each balloon has a monorail configuration so that anchoring the wires together enables simultaneous passage of both balloons. The system offers a number of advantages when compared with separate balloons. First, advancement and positioning of both balloons occurs simultaneously. This may save time when compared with two independent balloons that need to be advanced and positioned separately, and reduces the chance of one of the balloons being squeezed out of position by the other upon inflation, sometimes known as “lemon-seeding”. Second, passage of a single system is faster than two separate balloons, and the balloons are automatically in an overlap position. This allows the operator to concentrate more carefully on the patient and procedure rather than adjusting wire and balloon positions and contending with two indeflaters. Third, the system dilates both branches of a bifurcation simultaneously, therefore avoiding plaque or thrombus shift, also known as the “snow-plough” effect, into the ostium of the untreated vessel. The avoidance of plaque shift results in fewer balloon inflations and shortens the procedure. Finally, this bifurcation system passes easily through a 6 Fr guiding catheter, thereby facilitating the use of other entry sites such as the radial artery. Bifurcation systems have a number of limitations with regard to deliverability, deployment and sizing. First, it is of paramount importance to avoid entwinement of the wires. Using the kissing balloon technique, an individual balloon may pass a single or limited number of twists within the catheter or in the vessel before reaching the bifurcation, whereas the combined bifurcation system will tend to push any twists to the distal end and prevent delivery of the system. This problem is more frequent when the bifurcation lies distally in the coronary tree and the wires require extensive manipulation to pass into the appropriate branch. However, the carina of the LMCA is the most proximal bifurcation and does not require such extensive manipulation. Second, the simultaneous passage of two balloons, separately or as a single system, increases the stiffness and bulkiness of the system which may result in difficulty or failure when attempting to reach a distal lesion. The carina of the LMCA, therefore, is the ideal target for such a system. Third, the deployment of two balloons of correct size for the vessels may result in over-sizing in the section before the bifurcation. Such a problem is inherent in the use of two balloons and is unchanged with the bifurcation balloon system. Thus the disadvantages of the bifurcation balloon are, for the most part, minimized when the carina of the LMCA is the target. In this case, deployment of the bifurcation balloon system re-established TIMI 3 flow in both major left-sided vessels with a single inflation. No further interruption of re-established flow was necessary. Restoration of flow through the LMCA could potentially be followed by percutaneous stent placement^1,2 or by CABG.^7,8 In light of the patient’s presentation with stent thrombosis, it was decided to proceed to CABG. Conclusion. Left main shock syndrome with complete occlusion has an extremely poor prognosis, with the common occurrence of poor final flow, pump failure and multiorgan failure. The LMCA carina represents the most accessible and largest bifurcation in the coronary tree, and is a location where speedy treatment is advisable. The rapid restoration of flow in under 5 minutes using a bifurcation balloon system represents a new strategy for minimizing procedural complications. Such systems may aid prompt revascularization and act as a bridge to surgery or definitive PCI in similar circumstances. Acknowledgement. The authors are grateful to Joep Maeijer for help with preparation of the images.

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