Very early great saphenous vein graft aneurysm treated by percutaneous coronary intervention under ChromaFlo imaging guidance

Abstract

A 73-year-old man, who had undergone coronary artery bypass grafting (CABG) 10 days prior, presented with a great saphenous vein graft aneurysm (SVGA). CT revealed the increasing size of the aneurysm. Since the SVGA occurred immediately after CABG and there were no other complications, the aneurysm was treated percutaneously. While intravascular ultrasonography (IVUS) and optical coherence tomography failed to detect the entry point, an IVUS catheter with the addition of ChromaFlo imaging clearly revealed the entry point, size and length of the SVGA. To prevent migration and edge restenosis associated with covered stents, the covered stent (3.0×19 mm) was superimposed on a drug-eluting stent (3.0×28 mm) that covered the entry site. A follow-up study demonstrated the absence of flow into the aneurysm.

Background

Saphenous vein graft aneurysms (SVGAs) are a very rare (0.07%) but significant complication after coronary artery bypass grafting (CABG).¹ SVGAs tend to enlarge over time, resulting in aneurysm rupture, fistula formation and myocardial infarction.^2–4 Late aneurysm formation (identified >5 years after CABG) is common, and is thought to be secondary to SVG atherosclerotic degeneration.⁵ In contrast, early aneurysms (identified within 12 months after surgery) are thought to be caused by infection, vulnerability of the venous wall and technical factors relating to conduit harvesting, preparation and grafting.⁶ Herein, we report a case involving a very early SVGA, which was successfully treated percutaneously using ChromaFlo imaging to detect the entry site of the aneurysm.

Case presentation

A 73-year-old man, who had undergone CABG on the right coronary artery 10 days prior, was transferred to our hospital due to a SVGA detected by postoperative coronary angiography (CAG), which was performed to confirm graft patency prior to discharge. He had no fever or symptoms at arrival. His ECG revealed a normal sinus rhythm and no ST segment changes. His echocardiogram showed no pericardial effusion and the left ventricular wall movement was within normal limits. He had a history of hypertension, diabetes mellitus and dyslipidaemia. He had no family history of coronary artery disease.

Investigations

To further elucidate the aetiology, as well as the accurate location and growth of the aneurysm, repeated CT was performed. CT revealed the increasing size of the aneurysm; the maximum short diameter was 13 mm on the 10th day and was 20 mm on the 18th day after surgery (figure 1). CAG revealed a contrast jet flow into the SVGA (figure 2, see online supplementary video 1). Because CT showed communication between the aneurysm and the saphenous vein graft and both were simultaneously contrasted in CAG and CT, a pseudoaneurysm due to graft vessel damage was suspected.

Figure 1.

The arrow indicates SVGA which had enlarged from 13 to 20 mm in the maximum short diameter. SVG, saphenous vein graft; SVGA, SVG aneurysm.

Figure 2.

Coronary angiography shows a contrast jet flow into the saphenous vein graft aneurysm.

Differential diagnosis

Infectious aneurysms of the saphenous graft were deniable as the patient had no fever and inflammation agents, such as C reactive protein, were not elevated. Bacterial and tuberculous cultures were negative.

Treatment

Since the SVGA occurred immediately after CABG and there were no other complications, the aneurysm was treated percutaneously. Intravascular ultrasonography (IVUS) (Eagle Eye, Volcano, San Diego, California, USA) and optical coherence tomography (OCT) assessments (Ilumien, St Jude Medical, Minnesota, USA) failed to clarify the entry point of the SVGA (figure 3A). However, ChromaFlo imaging clearly revealed the entry point, size and length of the SVGA (figure 3B). A covered stent was used to seal the entry site. To prevent migration and edge restenosis associated with covered stents, a drug-eluting stent (DES; 3.0×28 mm) was first deployed to cover the entry site. Subsequently, a covered stent (3.0×19 mm) was deployed, superimposed on the DES.

Figure 3.

(A) The perforated site could not be detected on IVUS or OCT. IVUS, intravascular ultrasonography; OCT, optical coherence tomography. (B) The entry site was clearly detected using ChromaFlo imaging. SVG, saphenous vein graft.

Outcome and follow-up

Follow-up CAG, ChromaFlo imaging and OCT demonstrated adequate stent apposition and the absence of blood flow both around the stent edges and into the aneurysm (figure 4A and see online supplementary video 2; figure 4B; figure 4C). The patient has maintained stable conditions over a 2-year follow-up.

Figure 4.

(A) Coronary angiography showing the absence of flow into the aneurysm. (B) ChromaFlo imaging confirms a complete coverage of the entry site and the absence of flow into the aneurysm. (C) Optical coherence tomography showing a complete coverage of the entry site.

Discussion

To our knowledge, this is the first reported case of a very early SVGA successfully treated with a covered stent under the guidance of ChromaFlo imaging. Mortality rates of SVGAs for reported cases of surgical, percutaneous and conservative management were 13.9%, 6.1% and 23.8%, respectively.⁷ Revascularisation procedure is recommended for patients with symptoms and for patients with SVGAs of diameters exceeding 1 cm or if graft flow is diminished.⁸ A management algorithm for SVGAs has been previously proposed.⁷ Based on this algorithm, surgical treatment is preferable when fistula, rupture or compression of adjacent cardiac or vascular structures exist. In other cases, an intravascular treatment using a covered stent should be initially considered. In the present case, there were two issues requiring resolution¹: the difficulty in detecting the precise entry site of the SVGA and² the disadvantages of a covered stent. Covered stents very easily migrate and have a higher rate of edge restenosis compared with that of non-covered stents.^{9 10}

The resolution to the first issue (detecting the entry site of the SVGA) involved ChromaFlo imaging, which elucidates flow patterns and vessel diameters. ChromaFlo is an imaging modality that reveals the areas of blood flow (shown in red in figure 4B) in real time as the blood moves, which helps to differentiate blood from the static tissues of the vessel wall and stent struts. Thus, ChromaFlo can aid in assessing stent apposition, lumen size, dissection and thrombus identification. This has been validated both in coronary¹¹ and peripheral artery interventions.¹² In the present case, ChromaFlo imaging was very useful in detecting the precise entry point of the aneurysm, even when it could not be detected with greyscale IVUS or OCT.

The resolution to the second issue (the drawbacks of a covered stent) involved first deploying a suitable sized DES over the precise entry point of the SVGA. This built a ‘foundation’ to prevent the migration of the covered stent. Then, we deployed the covered stent superimposed on the DES. The length of the covered stent was shorter compared with that of the DES to prevent edge restenosis of the covered stent. The prevalence of acute and delayed migration of peripheral endovascular stents has been estimated to be approximately 2.5%–5%.^{13 14} The risk of stent migration is reported to be greater in the more dilated venous circuit compared with that in the arteries.¹³ In addition, because a covered stent impairs stent wall apposition to a greater extent compared with that for an uncovered stent,¹⁵ more aggressive stent oversizing is required to reduce the risk of stent migration, which may result in perforation. Predeployment of a DES may prevent stent migration and the need for an oversized covered stent, reducing the risk of perforation and edge restenosis.

Learning points.

• Saphenous vein graft aneurysms can be an acute-phase complication after coronary artery bypass grafting.

• ChromaFlo imaging is a very simple technique for detecting the entry site of an aneurysm.

• Predeployment of a drug-eluting stent can address the drawbacks of a covered stent.