Degenerated Saphenous Vein Graft: Down for the Count, But Not Out of the Fight

Coronary chronic total occlusions (CTO) have historically been treated with medical therapy.¹ With the advent of the North American hybrid algorithm, there has been increasing interest in percutaneous coronary intervention (PCI) of CTOs. Success rates for the treatment of CTOs have continued to increase as new catheters and guidewires have allowed for an antegrade or retrograde approach to the CTO vessel.^1,2 The hybrid algorithm recommends antegrade wire escalation, antegrade dissection with re-entry, retrograde wire escalation, and retrograde dissection and reentry. Sometimes the retrograde access to the target vessel may be an occluded or degenerated saphenous vein graft.³ In this case, we discuss the use of a vein graft that was not only degenerated, but also had a contained, ruptured pseudoaneurysm. The case review also addresses the various challenges posed by this conduit and the steps that were taken to overcome these challenges.

Case Report

A 73-year-old male with known coronary artery disease (CAD), status post coronary artery bypass graft (CABG) surgery presented to his cardiologist with worsening angina. He was known to have a left internal mammary artery to the left anterior descending artery and a saphenous vein graft (SVG) to the obtuse marginal-1st branch (OM), and had a known, occluded SVG to the right coronary artery graft. The patient underwent a stress echocardiogram, during which he developed typical angina and dyspnea after approximately 6 minutes of Bruce protocol. His stress electrocardiogram (ECG) showed slight ST elevation inferiorly with lateral ST depressions and T-wave inversions. Stress echo showed anterolateral ischemia. The patient underwent left heart catheterization that showed severe stenosis of the left main coronary artery, a CTO of the mid left circumflex (Figure 1), and a proximal contained, ruptured pseudoaneurysm of the SVG-OM with severe stenosis of the distal vessel (Figure 2, Video 1). Given the new findings in the SVG-OM, it was thought that the patient’s symptoms were likely secondary to his disease of the SVG-OM graft. After discussion with his family, the patient returned for native vessel CTO PCI of his occluded circumflex artery.

Procedural Details

Dual coronary angiogram was performed via bilateral common femoral artery access. The Japanese Chronic Total Occlusion (J-CTO) Score⁴ was determined to be 4 for blunt cap, length >20 mm, tortuosity, and calcification (Box 1). 

Initially, via the microcatheter (Turnpike Spiral, Vascular Solutions), antegrade wire escalation was attempted with a Fielder XT wire (Asahi Intecc) and a Pilot 200 wire (Abbott Vascular). The Pilot 200 wire was placed in the subintimal dissection plane of the circumflex artery. The “scratch and go” technique was performed with Confianza Pro 12 (Asahi Intecc) and Pilot 200 wires. The knuckle was extended to the OM branch, but a CrossBoss (Boston Scientific) could not be passed, despite dilation with a 1.5 x 20 mm compliant balloon. The Stingray LP catheter (Boston Scientific) also would not pass. Antegrade dissection re-entry attempts were abandoned.

Retrograde access was attempted via the degenerated SVG. However, there were several technical issues. First, there was poor guide support despite the use of guide extension and microcatheter use, due to the presence of a large proximal pseudoaneurysm. Second, the patient would become ischemic with diffuse ST segment depressions and chest pain whenever the microcatheter crossed the severe lesion in the distal SVG. Keeping in mind the ischemia issues, a Fielder XT wire was passed into the OM branch and a retrograde knuckle was created in the circumflex artery. Retrograde dissection and reentry technique (Reverse CART) were attempted, but were unsuccessful due to the presence of calcification and vessel tortuosity. The native circumflex could only accommodate a small 1.5 x 20 mm and 2.0 x 15 mm compliant balloons that did not allow for successful reverse CART. The patient was also experiencing chest pain and became restless with associated electrocardiographic changes; therefore, CTO PCI was stopped. The fluoroscopic time by this point was 50 minutes. The SVG lesion was treated with balloon angioplasty (Figure 3) (Boxes 2-3). 

The patient presented again approximately six weeks later for repeat CTO PCI, again via bilateral common femoral artery approach (Figures 4-5). During the procedure, an antegrade knuckle was created with Corsair Pro (Asahi Intecc) and Fielder XT wires. Similar challenges with guide support were encountered at the level of the vein graft, but ischemia did not recur. This was likely a result of the prior balloon angioplasty of the proximal SVG during the index procedure, even though angiographically, the distal SVG lesion appeared to be unchanged. The retrograde wiring of the OM was performed via the Turnpike LP microcatheter (Vascular Solutions) with a Fielder XT wire, followed by a Pilot 200 wire that allowed for the formation of a retrograde knuckle all the way into the proximal circumflex (Figure 6). The previous angioplasty of the native circumflex allowed for a 3 x 20 mm compliant balloon to be advanced, reverse CART was completed, and the retrograde wire (Pilot 200) was passed into the antegrade guide (Figure 7). Next, the Turnpike was taken to the antegrade guide and the Pilot 200 wire was removed. The RG3 (Asahi Intecc) wire was passed into the retrograde gear externalized via the Turnpike LP to the antegrade grade guide. Following wire externalization, the circumflex lesion was treated with a 2.75 x 38 mm Promus drug-eluting stent (DES) (Boston Scientific) immediately above the distal bifurcation to the proximal vessel. A 3.5 x 20 mm Promus DES was placed in the distal left main (Figure 8). Final angiography demonstrated excellent results with TIMI-3 flow of the left main and circumflex stents (Figure 9, Video 2). 

Follow-Up

At 4-week follow-up, the patient reported complete resolution of his angina. He was participating in cardiac rehabilitation without any disruption. Since his exercise capacity had been continually improving, another stress test was not performed, as the patient was doing extremely well clinically. Moreover, he was able to discontinue long-acting nitrates and had not used any sublingual nitroglycerin since his CTO PCI. 

Discussion

Coronary Chronic Total Occlusion

A coronary CTO is defined as 100% atherosclerotic vessel occlusion that has been present for at least 3 months and that results in a complete loss of antegrade blood flow.¹ The prevalence of CTO lesions exhibits marked variability in labs across North America, ranging between 18-59%.¹ One of the leading causes of death across the world is cardiovascular disease; namely, ischemic heart disease. While acute plaque rupture most commonly presents as a life-threatening condition, a large percentage of individuals with coronary artery disease experience a more progressive form of the disease, allowing for the formation of collateral vessels and chronic total occlusions. 

Despite the high prevalence of CTO lesions, only 6-9% are treated with percutaneous interventions in North America.² In some regions of the world, CTO lesions are treated more aggressively, such as in Japan, where 61% of CTOs are managed with percutaneous coronary intervention (PCI).³ It is unclear why there are such regional variations across the globe. CTO lesions may be less aggressively treated in North America due to the perception that revascularization in CTO patients does not alter natural progression of the disease, nor does it confer a benefit in terms of morbidity or mortality. There has been much controversy about the use of PCI to treat CTOs versus using coronary artery bypass graft surgery. The controversy is fueled by multiple factors, such as the vast differences in European and American guidelines for revascularization, along with the poor evidence available.⁵

Yet, for example, Joyal et al have shown a significant reduction in angina after revascularization in patients with CTO lesions over a 6-year period when compared with patients who were not successfully revascularized.⁶ In the TOAST-GISE study, patients who had successful CTO PCI were more likely to be angina-free (89% vs 75%) and were more likely to have a negative stress test (73% vs 47%) at 12 months compared to those with PCI failure.⁷ With the development of the more teachable North American hybrid algorithm for CTO lesions, along with the development of dedicated devices and wires for CTO PCI, success rates for CTO PCI have approached >85% at experienced centers.⁸ CABG patients tend to have more CTOs, possibly secondary to accelerated native vessel disease progression.^9,10 This results in an increase in the rate and complexity of the CTO that ultimately leads to reduced procedural success and an increased risk of complications. Potter et al have commented that treating CTOs with PCI prior to CABG referral may be more optimal for the patient.¹¹

Saphenous Vein Grafts

The use of saphenous venous grafts (SVG) for CABG was first pioneered by Rene Favaloro from Cleveland Clinic, thereby revolutionizing the surgical treatment of coronary artery disease.¹² Since its conceptualization, the utilization of saphenous veins for bypass grafts has long been the gold standard for the treatment of right coronary and circumflex artery lesions, with arterial grafts reserved for the left anterior descending artery. However, approximately ten years post surgery, only 60% of these venous grafts will remain patent.^13,14 Brilakis et al reviewed the post-CABG PCIs that were done in the veterans cohort from 2005 to 2013 and reported a SVG PCI rate of up to 26.6%.¹⁵ Notably, SVG PCI is associated with higher rates of peri-procedural myocardial infarctions and restenosis compared to native vessel PCI.^16-19 In a recent study by Liu et al, it was found that at 37 months post procedure, patients with native vessel PCI had significantly higher revascularization-free survival in comparison to those patients who had PCI of their SVG.²⁰ Brilakis et al also found that patients undergoing bypass graft PCI had higher risk characteristics and significantly higher rates of complications.⁹ 

In our case, the patient had a contained rupture with pseudoaneurysm formation in the SVG that added increased risk. We were faced with the option of treating the distal SVG lesion with a DES and then treating the proximal pseudoaneurysm with a covered stent vs treating the native circumflex artery CTO.

SVG PCI carries multiple risks of complications, such as distal vessel thrombosis, post procedural restenosis, and unconfirmed long-term efficacy.^11-19,21,22 SVG pseudoaneurysms have been treated with covered stents, but they carry very high restenosis rates.^23,24 Multiple studies have shown that native coronary artery PCI has better long-term results than SVG PCI.^15,18,25 Therefore, it was decided to proceed with CTO PCI of the native circumflex artery.

Retrograde Approach

Antegrade revascularization of CTO lesions in patients with prior CABG is often a more complex procedure due to the anatomical distortion of the native vessels that persist post CABG. In our patient, there were no suitable native coronary retrograde channels available. This resulted in initial antegrade attempts, but the calcification and tortuosity were major barriers, causing these attempts to be unsuccessful. Therefore, a retrograde approach was attempted via the SVG-OM. There were multiple procedural challenges that were dealt with during this procedure: 

1. The presence of a proximal pseudoaneurysm and inadequate guide support: the guide extension catheter could not be slowly advanced into the graft, despite the use of balloon dilation, due to the presence of the pseudoaneurysm. 
2. The microcatheter was delivered though the SVG, but the distal vein graft lesion caused ischemia for the patient. Balloon angioplasty of the lesion allowed for completion of PCI without discomfort to the patient. 

To Coil or Not to Coil the SVG

There is very little consensus regarding whether or not the vein graft supplying the native vessel should be coiled after completion of PCI. The two large registries on post-CABG CTO PCI utilizing SVGs as retrograde conduits were done by Dautov et al and Nguyen-Trong et al (Table 1).^20,26 While Dautov et al coiled 15 of 19 SVGs, Nguyen-Trong et al coiled only 2 of 21 SVGs, which were used as a retrograde conduit. In our patient, due to the presence of both a pseudoaneurysm and severe stenosis, it was decided not to coil the SVG.

Conclusion

Despite the frequent use of SVGs as bypass grafts, their long-term patency is frequently inadequate. In some patients with degenerated vein grafts that produce medically refractory angina or myocardial ischemia, native vessel CTO PCI can be performed safely and successfully using a SVG as a retrograde conduit. In our patient, despite the presence of a contained ruptured pseudoaneurysm, the vein graft was still able to be utilized for CTO PCI of the native vessel with good angiographic results and resolution of symptoms. Though CTO PCI can be technically challenging, new devices and specialized advanced training have increased the likelihood of successful CTO PCI. Furthermore, pros and cons should be balanced with careful consideration of the various approaches to CTO revascularization and the appropriate patient selection in order to achieve the maximum benefit.

References

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The authors report no conflicts of interest regarding the content herein.​

The authors can be contacted via Anbukarasi Maran, MD, FSCAI, FACC, at maran@musc.edu.