TEACHING COLLECTION

Stenting in Unusual Settings:
Rotational Atherectomy of a Stent-Jailed Septal Perforator: A Good Verdict for the Prisoner

Deepak Jain, MD, DM, Gert Richardt, MD, Hugo A. Katus, MD
Deepak Jain, MD, DM, Gert Richardt, MD, Hugo A. Katus, MD
Catheter-based techniques for revascularization offer a good solution to the vexing problem of stenosis in septal perforators, which are not accessible to surgical grafting, and which often are erroneously relegated as inconsequential. Stenosis of large septal perforators can cause angina, rhythm and conduction abnormalities, and ventricular septal ischemia.1,2 The latter could be particularly detrimental when there is ventricular dysfunction. Moreover, in situations of right coronary artery (RCA) occlusion, the septal perforators from the left anterior descending (LAD) branch are the principal source of collateral blood supply and vice versa;3 this fact could be important in post-coronary artery bypass grafting (CABG) patients who often have some grafts blocked in the backdrop of severe and complex native coronary artery disease. Vemuri et al. have shown that the angioplasty of large septal perforators is technically feasible and offers satisfactory long-term results. They observed a high primary success rate (95%) with no increase in complications, and good relief of symptoms up to 2 years.2 Stenting of a septal perforator has also been reported.4 The septal perforator ostium is the most common site of lesions and is functionally a branch ostial stenosis. While rotational atherectomy of ostial stenotic lesions has been described,5–7 a small series of 4 cases with successful rotational atherectomy in the septal perforator was recently published.8 We describe percutaneous coronary intervention (PCI) in two septal perforators in a post-CABG patient with a complex medical history. Case Report. A 60-year-old male presented in October 2000 with troponin-negative unstable angina. He was a known case of severe three-vessel with left main coronary artery (LMCA) disease and moderate left ventricular (LV) dysfunction, having undergone CABG in 1981 and a redo-CABG in 1996. In June 1998, he developed symptomatic bradycardia for which a dual chamber pacemaker was implanted. A month later he survived an episode of ventricular fibrillation, after which he was managed on an automatic implantable cardioverter defibrillator (AICD). Anginal symptoms redeveloped in February 1999 and were treated by rotational atherectomy of the LMCA and proximal LAD. About two months after this intervention, restenosis developed and stenting of the LMCA along with the proximal LAD was done. The first septal perforator (S1) was compromised in the 3 x 25 mm Bx Velocity stent (Cordis Corporation, Miami, Florida), but the fact was overlooked. Half a year later he developed in-stent restenosis, which was treated with balloon angioplasty; he continued to be in Canadian Cardiovascular Society (CCS) angina class II-III until he presented to us with unstable angina during the episode in question. The patient’s diagnostic angiogram revealed 25% in-stent restenosis in the LMCA and proximal LAD. The left circumflex (LCX) and RCA were totally occluded. Saphenous vein grafts to the LAD and first diagonal branch were patent and supplying collaterals to the LCX and RCA. The RCA also had significant collateral blood flow from two large septal perforator branches (S1 and S2) arising from the LAD. While S1 was jailed in the stent and had 90% ostial stenosis, the S2 was originating distal to the stent and had a similar high-grade ostial stenosis (Figure 1). Balloon angioplasty with provisional stenting of both S1 and S2 was decided. A 7 French (Fr) Judkins left (JL) 4 guiding catheter was selectively engaged and a 190 cm, 0.014´´ Hi-torque Floppy Extra Support wire (Guidant Corporation, Santa Clara, California) was steered into S1 without any noticeable difficulty. A 1.5 x 20 mm Adante balloon (Boston Scientific/Scimed, Inc., Maple Grove, Minnesota) was taken and passed over the wire. However, the balloon passage halted at the origin of S1 and it could not be delivered across the lesion despite vigorous pushing in conjunction with maneuvers like deep inspiration and coughing. Finding no possibility for balloon dilatation in S1, it was thought expedient to attempt the same in S2 and then exchange the Extra Support guidewire with a Rota Wire (Boston Scientific/Scimed, Inc.) in S1, and try to pass the Adante balloon over it, failing which we could resort to rotational atherectomy. A second Extra Support wire was thus threaded into S2 and the same 1.5 mm Adante balloon was easily passed across the ostial lesion (Figure 2). Two 1 minute inflations were done at 10 atmospheres and the balloon and guidewire were taken out after check pictures demonstrated a good dilatation. A Rota Wire Floppy was then exchanged into S1. The balloon, however, could not be passed over it and the idea of balloon angioplasty was abandoned. Consequently, a 1.25 mm burr was advanced to the platform segment and the platform speed was adjusted to 160,000 rotations per minute (rpm). Under rpm surveillance, avoiding excessive deceleration, slow and careful advancement of the burr was made through the lesion. It took about eight ablation runs (each lasting 15–20 seconds) to allow free and unhindered passage of the burr across the lesion. Thereafter, the burr-drive shaft assembly was taken out and the 1.5 mm Adante balloon was advanced over the guidewire; this was done easily. Two 1 minute inflations at 12 atmospheres were given and the final pictures showed a satisfactory intervention result (Figure 3). The patient fared well after this and there were no adverse in-hospital events. There was no cardiac enzyme release after the procedure. We last saw him in our outpatient department three months after PCI and during that period his symptoms were well controlled. Discussion. Rotational atherectomy as an innovative invasive modality to treat stenotic ostial lesions in sidebranches jailed by prior stent placement has been described anecdotally.9–12 In an interesting report by Morocutti et al., bail-out rotational atherectomy was done to salvage the main vessel jailed after treatment of a bifurcation LAD stenosis with the “trousers” technique.13 The mechanism of rotational ablation in this setting has been elucidated in in vitro experimental models of various stents. The scaffolding structures of the stents were destroyed due to loss and deflection of the struts, and the maximum size of the ablated stent particles differed according to the stent design: smaller in slotted tube stents and larger in coiled stents.14 It is therefore evident that rotational atherectomy has definite potential to ablate the stents when used during intervention for jailed sidebranches. The angioplasty of septal perforators is challenging. The sharp angulated origin and the ostial location of the lesion in the majority of cases make the passage of hardware difficult and the dilatation entails a definite risk to the all important LAD. Besides, the small size and tendency for elastic recoil make the procedure less rewarding. Rotational atherectomy is even more challenging owing to the fact that the Rota Wire may need greater skill during passage because of thin lubricated coating, smaller diameter, and exchange length (this problem can, however, be circumvented by first passing an ordinary guidewire and then exchanging it for a Rota Wire through a suitable transport catheter), and the sharp angulated branch origin predisposes to the risk of perforation. Moreover, there is a possibility of microvascular obstruction with embolization of stent particles when the procedure is performed to treat in-stent restenosis. On the other hand, this technique seems to be well suited for interventions in septal perforators. The principle of orthogonal displacement of friction eases the passage of the burr through the sharp angulations. This fact, coupled with its ability to ablate stents, makes it an enterprising technique for major sized stent-jailed septal perforators. Conclusion. We describe rotational atherectomy in a septal perforator branch jailed by prior stent implantation in the LAD. Two important points emerge from our report. First, the situation of an ostial lesion in a sidebranch jailed by prior stenting is entirely different from a de novo branch ostial lesion. More often than not a routine coronary angioplasty can be done in the latter, while the former might need advanced techniques. Second, rotational atherectomy offers a unique opportunity to treat jailed septal perforators, and should be resorted to in situations where the branch is large and benefit is thought to accrue.
References
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