Fig. 17.1
Double kissing (DK) crush stenting (proximal SB re-crossing) for distal LM bifurcation (distal bifurcation angle of 90°). (a) SB stent deployment. (b) The balloon in the MV was inflated to crush the SB stent. (c) Proximal SB re-crossing. (d) First kissing balloon inflation. (e) MV stent deployment. (f) Proximal-middle SB re-crossing. (g) SB balloon dilation. (h) MV balloon dilation. (i) FKBI. (j) Proximal optimization technique (POT). (k, l) The stent strut of SB ostium was well appositioned without gap formation. (m–o) The electronically cut stents show a clear viewing of the SB ostium. MV main vessel, SB side branch, FKBI Final kissing balloon inflation (Acknowledgement: Reprinted from Jun Jie Zhang [17])
However, things are not easier than you think. As we found from the bench test for classic crush that rewiring SB is necessary to repair distorted SB stent [8]. Operators always need to pay more attention to rewire SB from proximal MV stent cell. As rewiring SB from distal MV stent cell could increase the possibility of wire going between stent and vessel wall, which will leave a gap at the ostium after balloon crushing (Fig. 17.2) [8]. The methods to confirm the exact position of SB wire are as following: visual assessment from fluoroscopy (Orthogonal projections to confirm SB rewiring from the proximal MV stent cell, online video), guidance with intravascular ultrasound (IVUS) or optical coherence tomography (OCT) from MV. Sometimes, it is difficult to advance balloon to SB after wire position in the true lumen of SB stent. One alternative is to inflate a balloon in distal MV to provide extra support (namely, balloon anchoring technique). Otherwise, minimal size balloon (such as, 1.5 mm) can be tried, followed by relative large one. Alternative inflation using non-compliant balloon (with the balloon/stent ratio of 1:1) at ≥16 atm starting from SB is recommended before first kissing and FKBI. Two non-compliant balloons are usually inflated at ≥12 atm during FKBI [10]. Proximal optimization technique (POT) is mandated to achieve well apposition of proximal MV stent unless IVUS or OCT confirms no presence of stent strut malapposition at proximal MB. Flow-limiting dissection at proximal, distal edge of MV, or distal edge of SB entails bailout stent.
Fig. 17.2
Classic crush stenting (distal re-crossing SB) for distal LM bifurcation (distal bifurcation angle of 90°). (a) SB stent deployment. (b) MV stent deployment to crush the SB stent. (c) Gap formation near the carina (arrow). (d) Distal SB re-crossing, wire going between the SB stent and vessel wall. (e) SB balloon dilation. (f) Final kissing balloon inflation. (g, h) Leaving a significant gap near carina (arrow). MV main vessel, SB side branch, FKBI Final kissing balloon inflation (Acknowledgement: Reprinted from Jun Jie Zhang [18], with permission from Europa Digital & Publishing)
Clinical data, comparing DK crush versus either classic crush or other stenting techniques mainly come from the serial randomized DKCRUSH trials. Initially, we reported that FKBI was successfully performed in 100% by DK crush [5], compared to 80% in classic crush. In DKCRUSH-I study, we demonstrated that DK crush was associated with a significant reduction of ST, ISR and major adverse cardiac events (MACE) in treating patients with true bifurcation lesion compared to classic crush [11]. Interestingly, DKCRUSH-II trial [10] for the first time showed a significant low rate of target lesion revascularization (TLR) after DK crush for complex bifurcation lesions at 1-year follow-up, compared to provisional T stenting technique. Recently, the DKCRUSH-III study including patients with distal left main bifurcation lesions showed that 3-year clinical outcomes and 13-month angiographic results were in favor of DK crush when compared with culotte stenting technique [12, 13] in term of TVR, MI, ST and MACE. Furthermore, IVUS analysis confirmed better strut apposition in DK crush stenting group [14]. In addition, clinical results from the studies also supported the priority of DK crush to other stenting techniques for left main bifurcation lesions at long-term follow-up [11, 15]. Taking insight analysis from those DKCRUSH trials, it is too early to admire that DK crush is the best mousetrap for stenting bifurcation lesions. Actually, whether DK crush can achieve favorable outcomes in patients with more frequent morbidities (myocardial infarction, left ventricular dysfunction), longer SB lesion length and more complex lesions (chronic total occlusion, calcified and thrombus containing lesions) has not yet defined. Furthermore, no two bifurcation lesions are identical. It sounds superficial if we consider that all true bifurcation lesions belong to complex lesions. By our DEFINITION study [16] relying on anatomical variables from 3660 patients with Medina 1,1,1 and 0,1,1 bifurcations and SB diameter minimal 2.5-mm, complex bifurcation lesions only account for 30% among all true bifurcation lesions, with 70% classified in simple bifurcation lesions. All two-stent techniques did not show any benefits over one-stent approach for the simple bifurcation lesions. In contrast, two-stent techniques for complex bifurcation lesions were associated with less in-hospital mortality and 1-year MACE than one-stent technique. Apparently, before making final decision of the stenting technique selection, lesions stratification with this novel method is recommended. Of course, the superiority of DK crush over provisional stenting or other complex stenting techniques for the new defined complex lesion needs to be tested in the following randomized studies.
In summary, available clinical data supported the advantages of DK crush over other stenting techniques for more complex coronary bifurcation lesions. This technique consists of stenting SB, balloon crush, first kissing, stenting MV, and FKBI. Carefully rewiring from proximal cell of MV stent and maintaining the wire in the true lumen of SB stent is critical for optimal angiographic results at follow-up. Balloon anchoring from MV, alternative inflation and each kissing inflation using large enough non-compliant balloons at high pressure, and POT technique are mandatory to improve both angiographic and clinical outcomes. Imagining modalities are useful to guide SB rewiring and assessment of procedure quality. Stratification of a given bifurcation lesions is recommended before decision-making.
Fig. 17.3
DK crush stenting through radial approach for distal LM bifurcation lesion case: (a) A 1,1,1 distal LM lesion. 6 Fr GC through left radial approach. (b) SB stent deployment. (c) 3.5 mm balloon in MV inflation to crush SB stent. (d) Rewiring SB from proximal cell. (e) First kissing balloon inflation. (f) MV stent deployment. (g) Non-compliant balloon in SB inflation at 20 atm. (h) Non-compliant balloon in MV inflation at 20 atm. (i) Final kissing balloon inflation. (j) Final result. (k) Thirteen-month angiographic FU
17.2 Part 2: Optimized Provisional Stenting for Treatment of Coronary Bifurcation Lesions
Liang Long Chen4
(4)
Beijing, China
17.2.1 The Procedural Essence
The optimized provisional T-stenting (OPT) distinguished itself from the classic provisional T-stenting (CPT) mainly in adoption of the ostial optimization technique (OOT), which can efficiently solve the dilemma in stent positioning and coverage of the SB ostium as rescue SB stenting is indicated, resulting in seamless connection between the two bifurcated stents.
17.2.2 The Procedural Indications
All CBLs can be treated with OPT on the premise of a reliable SB protection. OOT is able to turn the redundant MB struts over the SB ostium onto its upper ostial rim (struts ectropion), facilitating subsequent stent positioning and implanting if necessary for rescue SB stenting, or achieving “2-stent effect with 1-stent implantation” if not necessary for rescue SB stenting.
17.2.3 The Procedural Steps
OPT can be performed either via radial or femoral approach. 6–7 Fr. Guiding catheters with bigger lumen, open-cell stents with larger cell, and guiding wires with better shaping and recovering memory are preferred for the procedure. The procedural steps are schematically illustrated as follows (Fig. 17.4):
Fig. 17.4
Diagram of OPT procedural steps (Image provided courtesy of Medtronic Inc. © Medtronic Inc. All rights reserved)
17.2.4 The Key Steps: Tricks and Points
- 1.
Pre-imbedded balloon for prevention of SB occlusion or carina shifting
Pre-imbedded balloon in the SB prior to the MB stenting is most effective for preventing its intra-procedural occlusion irrespective of occupying some catheter lumen. If used, the balloon should be stayed aside the MB stent, and then inflated simultaneously with the MB stenting and deflated after deflation of MB balloon, such a maneuver can prevent SB occlusion and/or carina shifting caused by MV/MB stenting, ensure rewiring the SB as closer as possible to the original carina position, thereby leading to a better result of OOT.
- 2.
SiKBD for optimization of ostial SB
As the most crucial step, SiKBD can be achieved by firstly inflating of the SB balloon followed by inflating of the MB balloon such that a better resultant direction of expanding-force can be generated to turn the abundant MB struts over the SB ostium onto its upper ostial margin, resulting in better effect of strut ectropion or better result of OOT.
17.2.5 The Typical Cases of OPT
The following case examples (Figs. 17.5, 17.6, and 17.7) demonstrate that OPT has broad indications for treating various CBLs including different anatomy (Y-/T-angulation and/or great BDD) and lesion locations [left main coronary artery (LM) or non-LM CBL] and also illuminate how to properly complete OPT by addressing the frequent problems and their solutions.
Fig. 17.5
LM bifurcation lesion treated with OPT. This was a male patient, aged at 65 years, admitted due to NSTEMI. Extensive ST depression was noted in leads V1–9, I and aVL with ST elevation in lead aVR. Echocardiography detected left ventricular ejection fraction of 45 % with extensive left ventricular hypokensia. (a–c) CAG shows a true LM CBL with severe stenosis in distal LM, ostial LCX and moderate stenosis at ostial and proximal LAD, and a roughly normal RCA. (d) After pre-dilating LAD and LCX, stent LAD-LM first with a balloon deeply imbedded in LCX for branch protection. (e, f) Stenting LAD leads to severe pinching of ostial LCX but normal TIMI flow. (g–i) U-bend wiring technique for rewiring LCX: Slightly rotate and advance the U-bend wire into LAD deeply or at least over the carina level (g); pull the wire back to the carina level and then steer the wire to LCX direction (h); and finally, rewire LCX at a point as closer as possible to the carina (i). (j) OOT technique: align the proximal markers of the two balloons at POC level and perform siKBD to optimize ostial LCX. (k) Residual stenosis still exists at ostial LCX. (l) Position LCX stent by aligning its proximal marker at the carina level. (m, n) After LCX stenting, there is residual stenosis at ostial LCX due to hard plaque. (o) Perform fKBD with two non-compliance balloons to end the procedure. (p–r) There is no more residual stenosis at ostial LCX and seamless connection between the two stents can be reached without protrusion of the LCX stent into LM. CAG coronary angiography, LM left main coronary artery, LAD left anterior descending artery, LCX left circumflex artery, OOT ostial optimization technique, POC polygon of confluence, siKBD sequential intermediate balloon dilation, fKBD final kissing balloon dilation. Abbreviations are similar in the following cases unless noted otherwise
Fig. 17.6
LAD bifurcation lesion treated with OOT. This was a female patient, aged at 53 years, admitted due to exertional chest pain. ST depression was noted in leads V2–6 and left ventricular ejection fraction was 63 % assessed echocardiographically. (a) CAG shows a true CBL involving LAD and the first diagonal branch (D1). (b) Pre-imbed a balloon in D1 (arrow), and then stent LAD, which severely pinches D1 with TIMI flow <3. (c) Rewire D1 at a point close to the carina, and then perform siKBD. (d) The redundant LAD struts over the D1 ostium are turned onto the upper rim of D1 ostium (arrow). (e) Ostial pinching is lessened with only focally mild residual stenosis. (f) The result is well maintained as shown in angiographic follow up at 12 month
Fig. 17.7
LM bifurcation lesion treated with OOT. This was a male patient, aged at 56 years, admitted due to unstable angina. Extensive ST depression was noted in leads V1–9, I and aVL and left ventricular ejection fraction was 51 % echocardiographically. (a) CAG shows a true LM CBL with severe stenosis involving ostial and proximal LAD and LCX. (b) Stent LAD after predilating LAD and LCX, which jails the balloon still stayed in LCX as shown in left anterior oblique projection (arrow). (c) Rewire LCX at a point as closer as possible to the carina and then withdraw the jailed balloon and wire. (d) OOT technique: advance 2 balloons respectively over LAD and LCX wires with aligning their proximal markers at the POC level, and then perform siKBD. (e, f) Rescue T-stenting is not indicated due to no residual stenosis at ostial LCX
Figure 17.5 illustrates all procedural steps of OPT particularly the key steps (e.g., balloon branch protection, U-bend wiring technique and siKBD) in treatment of a LM-CBL patient with great DBA. Figures 17.6 and 17.7 exhibits OOT is able to achieve “2-stent effect with 1-stent implantation”, thus avoiding rescue SB stenting (OOT only).
17.2.6 Provisional Stenting Family and Clinical Relevance of OPT
The provisional T-stenting offers an option between 1- and 2-stent techniques. If used properly, CPT is an efficacious treatment with reasonable cost [19–25]. However, there are two unresolved issues associated with CPT [24, 25]: (1) the potential risk of SB occlusion, (2) difficulty in stent positioning and coverage of the ostial SB as requiring the rescue T-stenting. The former has been solved by pre-imbedded protecting balloon technique [26, 27], whereas the later has not regardless of lots attempting. As well known, when the rescue T-stent is required for the SB with using CPT, it is difficult to accurately position the stent at ostial SB, particularly in Y-type lesion. If the proximal stent edge is aligned with inferior margin of the SB ostium, then there are no struts covering the superior margin of the SB ostium, thus being prone to develop in-stent restenosis. On the contrary, if the proximal stent edge is aligned with superior margin of the SB ostium, then the SB stent has to protrude into the MV, thereby resulting in suspension of partial stent inside the MV, thereby increasing the potential risk of in-stent thrombosis. Accordingly, several techniques, such as the T and small protrusion stenting (TAP), inner crush stenting, conventional culotte stenting and so on, have been used as alternatives for the rescue SB stenting with expectation of more complete coverage of the bifurcated area and less difficulty in ostial stent positioning. TAP, as used for the rescue SB stent, has been demonstrated to be easier in positioning of the SB stent and more complete in stent covering of the bifurcated lesion with favorable long-term clinical outcomes [28–30]. However, theoretically, all these techniques will introduce new problems due to increasing the metallic or drug burden at the bifurcated area or altering the bifurcated vessel/stent configuration or local hemodynamics, likewise leading to increasing the risks of in-stent restenosis and thrombosis.
The proximal optimization technique (POT) was introduced mainly for improving proximal stent lumen with somehow optimizing the SB ostium [31]. Despite that POT favored rewiring the SB and rewiring it closer to the carina so that the resultant stenting quality may be improved, the optimization afforded by POT alone is imperfect: (1) it is difficult to achieved “2-stent effect with 1-stent implanting” owing to the limited strut ectropion from the MB stent into the ostial SB, thus remaining at risk of acute branch occlusion, residual stenosis and in-stent restenosis, (2) it is still difficult to accurately position ostial SB stent as requiring a rescue T-stent.
Besides POT, we first proposed OOT to optimize the ostial SB after MB stenting. OOT is characterized by siKBD or snuggling balloon dilation. Briefly, for 1-stent or CPT without requirement of a rescue SB stent, a smaller SB balloon (balloon/SB diameter of 0.75 or less), and for CPT with requirement of a rescue SB stent, a bigger SB balloon (balloon/SB diameter of 1.0 or bigger) should be chose to perform siKBD with the MB balloon. After OOT, the redundant MB stent struts over the SB ostium can be overturned into (strut ectropion) and cover the upper margin of the SB ostium, resulting in somehow “2-stent effect with 1-stent implanting” if not necessary for a rescue SB stent, or facilitating subsequent stent positioning and implanting if necessary for a rescue SB stent. Our in vitro study demonstrated that OOT are associated with more benefits as compared to TAP or CPT, for examples, technically easier to perform, more accurately to position the SB stent, better stent coverage of the ostial SB, less metal and/or drug burden in the bifurcated arena, better bifurcated vascular or stent configuration and local hemodynamics, which may be expected to reduce in-stent restenosis and thrombosis. In fact, our initial clinical application also shown that after OOT it was so easy to position a rescue SB stent just by positioning the stent proximal marker at the carina level such that accurate connection between the SB and MB stents could be readily achieved, thereby effectively avoiding stent over-protrusion or incomplete coverage.
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