Guide Catheter Extension for Complex Percutaneous Coronary Interventions: A Necessary Double-Edged Sword

Guide catheter extensions — the GuideLiner (Teleflex) (Figure 1) and the Guidezilla (Boston Scientific) (Figure 2) — are tremendous tools that have been added to the armamentarium of interventional devices often necessary for the success of complex percutaneous coronary interventions (PCI) in difficult coronary anatomy. The use of these devices has been particularly helpful in the coaxial engagement of coronary ostia with unusual takeoffs, which are not easily accessible with traditional guide catheter shapes. They offer a significant advantage in the delivery of interventional devices into significantly tortuous and calcified coronary segments. They also play a major part in complex interventions involving chronic total occlusions and long saphenous vein grafts with difficult angles. Additionally, they offer substantial additional support to guide catheters especially in PCIs involving radial artery access where upsizing guide catheter diameter or using long, supportive sheaths are not possible. Another advantage lies in the careful, low injection rate, and selective coronary branch angiography, which improves visualization and substantially decreases contrast volume. 

On the other hand, one must be absolutely cautious in the use of these very valuable devices, as they can lead to significant complications in coronary anatomies that are already difficult. It is crucial to understand the dynamic interaction of these devices with the guiding catheter, coronary artery wall, balloons, stents, and various coronary interventional devices, in order to avoid related complications. The most important concern is the potential for arterial wall dissection, which can happen in three different situations: 1) Non-centered advancement of guide catheter extensions into tortuous, diseased, and calcified coronary artery branches; 2) Ejection of the non-secured guide catheter extension into a coronary artery branch during a vigorous contrast injection through the guiding catheter with a loose Y-connector valve; 3) Injection of contrast while the child catheter is parked in a non-coaxial position relative to the axis of the intubated coronary artery branch, especially when there is slight dampening of the pressure waveform. Another concern involves prolonged pressure dampening during the intubation of a small to intermediate sized target vessel, which can lead to worsening myocardial ischemia. Finally, a complication that is much less likely to occur with the most recent iterations of the child catheter designs involves longitudinal stent deformation and stent/balloon separation that occurs during the interaction of the stent delivery system with the proximal port of the child catheter within the mother guiding catheter.

In order to exemplify the advantages and disadvantages of guide catheter extensions, we thereby present a case of a complex PCI.

Case Report

A 46-year-old gentleman presented to the outpatient cardiology clinic with lifestyle-limiting, Canadian Cardiology Society (CCS) class III stable angina that was not responding to optimally tolerated, guideline-directed medical therapy (three antianginal agents at maximally tolerated doses).  

Ten months prior to his current presentation, the patient had an inferior myocardial infarction and required an urgent revascularization of an occluded mid right coronary artery and placement of a drug-eluting stent. At that time, his coronary anatomy revealed a severe mid left anterior descending artery focal stenosis that was treated in a staged fashion with a drug-eluting stent. He also had a severe distal left circumflex artery stenosis extending to the proximal subsegment of a small third obtuse marginal branch. Due to the relatively smaller myocardial territory and the difficult angle of takeoff of the left circumflex artery from an already tortuous left main segment, the decision was made to treat this coronary territory medically and monitor the patient’s clinical progression. However, despite progressive up-titration of guideline-directed antianginal therapy, this young patient’s anginal symptoms remained lifestyle limiting. 

His medical history also included a bicuspid aortic valve, hypertension, and mixed hyperlipidemia. Social history included tobacco abuse. Family history revealed premature obstructive coronary artery disease. Physical examination was unremarkable besides a body mass index of 37.5. No cardiac murmurs were noted. A 12-lead electrocardiogram showed sinus rhythm with evidence of an old inferior myocardial infarction. Transthoracic echocardiogram revealed normal overall left ventricular systolic function with an ejection fraction of 55%, stage II diastolic dysfunction, chronic mild hypokinesis of the mid and basal inferior segments, and a bicuspid, mildly calcified aortic valve without hemodynamically significant stenosis or regurgitation.

Given the anticipation for the need of significant support, this case was performed from a right common femoral artery access with a 6 French (Fr) extra backup (XB) 3.5 guiding catheter through a 6 Fr × 45 cm sheath. Figure 3 and Video 1 show a left anterior oblique (LAO) projection of the left coronary artery (LCA) system. The unusual aspect of the LCA anatomy is the tortuous mid left main (LM) segment approaching an 80^° angle, which then gives rise to the left circumflex (LCx) artery at a very steep obtuse angle in the opposite direction. The addition of the two angles of the mid-LM tortuosity and the LCx artery takeoff comes close to 290^°. This interesting anatomy, combined with the distal aspect of the LCx lesion extending to a small size third obtuse marginal branch (OM3), made this case relatively complex.

Figure 4 and Video 2A and Video 2B show the LCx in antero-posterior (AP) caudal and right anterior oblique (RAO) caudal projections. Due to the cumulative 290^° angle between the takeoff of the proximal LM segment and the direction of the LCx artery, it was not possible to advance a wire past the proximal LCx artery segment. Four different wires were used (Sion Blue [Asahi Intecc], Whisper extra support [ES] [Abbott Vascular], Choice Extra Support [Boston Scientific], and Whisper medium support [MS] [Abbott Vascular]) without successfully passing beyond the proximal LCx segment, due to recurrent wire prolapse back into the ramus branch once the wires made the turn into the mid LCx segment. The friction caused by the LCx angulation eliminated the transmission of torque to the tip of the wire despite the use of polymer-jacketed and hydrophilic wires (Figure 5 and Video 3). We did not think that advancing an over-the-wire low-profile balloon or straight microcatheter would help in this situation, because there was not enough wire purchase into the vessel to advance these devices without a recurrent wire prolapse. 

At this point, the device used to wire the vessel successfully was a SuperCross 120^° angulated coronary microcatheter (Teleflex) (Figure 6). In order to effectively wire the angulated LCx without the risk of subintimal wire passage, the SuperCross 120^° was advanced over the wire into the ramus branch, then pulled back to the distal LM at the site of the visualized takeoff of the LCx. The Whisper MS wire was pulled back to the tip of the microcatheter and then advanced into the LCx artery. The OM3 branch was wired with excellent torque transmission to the tip of the wire through the dedicated microcatheter (Figure 7 and Video 4A and Video 4B). The Whisper MS wire was then exchanged for Choice ES wire through the SuperCross 120^°, in order to improve the deliverability of a stent to the distal tight lesion.

A 6 Fr GuideLiner V3 catheter was advanced without any resistance to the ostium of the LCx to overcome its angulation and improve the deliverability of interventional devices. It was not placed in the proximal LCx artery at this point in the case in order to minimize the procedural risk. The injection rate through the GuideLiner was decreased to 2ml/s at 300 psi for a total of 3 ml per injection to minimize the chance of an iatrogenic dissection. A 2.0 mm x 12 mm Trek balloon (Abbott Vascular) was used for angioplasty of the OM3 and mid-LCx lesions twice, due to significant recoil (Figure 8 and Video 5A and Video 5B). 

Because of the difficulty in advancing the balloon to the lesion, the significant recoil, and the distal location of the lesions, a significant challenge was expected in delivering the stent to the treated segments, so we decided to advance the GuideLiner in a centered fashion over the shaft of the balloon into the proximal LCx. There was no resistance during slow, meticulous advancement. A 2.25 mm x 18 mm Xience Alpine drug-eluting stent (Abbott Vascular) was then successfully delivered to the OM3 lesion. Since the stent was brought down to its appropriate destination, and in order to prevent an injection-related proximal LCx dissection, we preferred to pull the GuideLiner back to the distal LM and then perform an angiogram for precise positioning of the stent prior to deployment.

Despite all the efforts to avoid an iatrogenic dissection, the following low injection rate angiography revealed a flow-limiting spiraling dissection extending from the proximal LCx to the OM3 with TIMI-0 flow. The distal LM showed a pseudo-lesion related to wire bias, but there was no dissection proximal to the ostium of the LCx. The stent was deployed using the takeoff of the atrioventricular circumflex branch as a reference, since there was no distal flow to mark adequate distal stent edge positioning (Figure 9 and Video 6). Angiography after distal stent deployment revealed that the stent effectively tacked the distal edge of the spiraling dissection with restoration of TIMI-3 flow (Figure 10 and Video 7).

At this point, the GuideLiner was positioned in the mid LM and a 3.0 mm x 28 mm Xience Alpine drug-eluting stent was meticulously positioned proximally to cover the LCx ostium, which was the proximal site of the dissection, without protruding into the left main and without partially covering the takeoff of the ramus branch (this was possible due to the steep obtuse angle). The proximal stent was overlapping the distal stent by 2 mm (Figure 11 and Video 8). The advancement of the proximal stent was challenging and required a lot of guide catheter support with slow and steady pushing on the stent delivery system.

Following the proximal stent deployment, one of the most important steps required to finalize the treatment of this complex anatomy was to reintroduce the GuideLiner into the stented segments in order to deliver the post-dilation noncompliant balloons, which have larger crossing profiles and are usually less deliverable, especially through the proximal stent struts. The key aspect of this technique is to advance the GuideLiner while the stent balloon is being slowly deflated, in order to keep it centered and to avoid it being stuck at the proximal stent struts due to the steep angle of LCx takeoff (Figure 12 and Video 9).

The OM3 stent was post dilated with a 2.25 mm x 12 mm NC Trek balloon inflated at 12 atmospheres (atm) in the distal subsegment and 16 atm in the proximal subsegment. The proximal to mid LCx stent was post-dilated with a 3.25 mm × 12 mm NC Trek balloon inflated to 12 atm in the distal subsegment and 14 atm in the proximal to mid subsegments.  

Again, it is important to re-advance the GuideLiner into the stent during proximal post-dilation balloon deflation in order to regain access to the vessel, in case further interventional work is required or if there are distal wire-related complications after wire pull. The following angiography revealed an excellent angiographic result with complete resolution of the dissection, TIMI-3 flow, grade 3 blush, and no distal wire-related complications (Figures 13-14 and Video 10 and Video 11).

The patient’s angina completely resolved after the procedure and he has since remained symptom free.

Discussion

Ten technical tips to minimize the risk of guide catheter extension-related complications:

1. Avoid advancing the guide catheter extension against any resistance, especially in the setting of steep angles.
2. Avoid engaging a guide catheter extension in the presence of ostial branch disease.
3. Avoid engaging a 6 Fr guide catheter extension in a vessel smaller than 2.5 mm.
4. Manipulate the mother guide catheter engagement to optimize the direction of entry of the child catheter into the coronary branch.
5. If possible, deliver the guide catheter extension over the shaft of a coronary balloon. Depending on the anatomy and how balloon inflation affects centering of the guide catheter extension in the vessel, one can choose to deliver a guide catheter extension while the balloon is inflated or deflated. It is absolutely crucial to avoid advancement of the guide catheter extension if minimal resistance is encountered. In some anatomical subsets, inflation of a short balloon at a different proximal or distal location within the lesion can be attempted in order to optimize centering of the guide catheter extension in the vessel prior to advancement. 
6. The GuideLiner Navigation catheter is a now-discontinued device made by Teleflex that served as a “dilator” to the GuideLiner and helped in providing safer navigation through tortuous and calcified anatomy (Figure 15). 
7. The injection rate should be dropped to at least half of the usual rate when the guide catheter extension engages the coronary branch.  If dampening of the pressure waveform is encountered, it is absolutely important to pull the guide catheter extension back to a location where this completely resolves prior to selective injection.
8. The Y-connector valve of the guide catheter should be tight and the external guide catheter extension push rod should be manually held during selective injection to avoid it from being ejected into the coronary branch.
9. Hold back pressure on the guide catheter extension external push rod while pulling devices out of the coronary branch in order to avoid it from diving in.
10. If the anatomy is unfavorable for the advancement of post-dilation balloons into stented segments and if the vessel size allows, a guide catheter extension can be advanced through the stent during stent balloon deflation in order to secure access for post dilation. 

Disclosure: Dr. Hady Lichaa and Cooper Santucci, BS, RT(R)(CI) report no conflicts of interest regarding the content herein.​

The authors can be contacted via Dr. Hady Lichaa at hady.lichaa@gmail.com.