Identifying and Repairing Dissections Using Intravascular Ultrasound: Are We There Yet?

Abstract

We present a case of intravascular ultrasound (IVUS)-based repair of a dissection using the Tack Endovascular System (Intact Vascular) following angioplasty of a superficial femoral artery (SFA) de novo lesion with a drug-coated balloon (DCB). This case illustrates the importance of IVUS in characterizing dissections and brings forward the question of whether IVUS should be used as the primary modality to identify and repair dissections.

VASCULAR DISEASE MANAGEMENT 2019;16(8):E107-E108

Key words: intravascular ultrasound, dissections, femoropopliteal interventions, peripheral arterial disease

Dissections are an inevitable consequence of angioplasty. Angiography, however, is suboptimal in identifying dissections. Intravascular ultrasound (IVUS) has been shown to identify 4 to 6 times more dissections than angiography, using the iDissection classification.^1,2 In this classification system, dissections are graded based on circumference (>180 or ≤180 degrees) and depth of dissection (intima, media, adventitia). Wider dissections are likely to be associated with suboptimal acute results, while deeper dissections involving the media/adventitia are likely to affect long-term outcome.^3,4 Repairing dissections seen on angiography, irrespective of their severity, has yielded positive outcomes even in patients receiving drug-coated balloons (DCBs), as was shown in the TOBA II study.⁵ We present a case of a focal non-flow-limiting National Heart, Lung, and Blood Institute (NHLBI) type B dissection repaired through use of the newly FDA-approved Tack Endovascular System (Intact Vascular), which has a wider circumference on IVUS. The potential benefit of this IVUS-based approach for dissection repair is discussed. 

Case report

A 62-year-old woman presented with severe claudication of her right lower extremity. Left common femoral artery access was obtained using a 6 French sheath under fluoroscopic guidance. Selective contralateral right superficial femoral artery (SFA) angiography with right lower extremity runoff was performed. A 6 French Destination Guiding sheath (Terumo) was placed into the distal right external iliac artery via the contralateral approach. The right common femoral artery was severely calcified, with 70% narrowing. Shockwave lithoplasty (Shockwave Medical) was performed in the contralateral right common femoral artery, followed by the 6 × 40 mm IN.PACT Admiral (Medtronic) DCB. There were no dissections visible on angiography, less than 10% residual narrowing, and good flow down the vessel. We proceeded with the treatment of the right SFA in its proximal segment at an area of focal 90% disease, using a 4 × 40 mm IN.PACT balloon for 3 minutes. A focal NHLBI type B dissection was seen in the treated segment, which was non-flow-limiting (Figure 1). IVUS was performed and revealed a dissection flap within the treated segment that was 180 degrees in circumference, involving the intimal layer. We elected to deploy two Tack implants to the location of this A2 dissection (intimal with 180 degrees circumference). The Tack implants were post dilated with a 6 ×  40 mm Ultraverse balloon (BD). Zero percent residual narrowing and a complete sealing of the dissection were seen on IVUS.  

Discussion 

Dissections are a consequence and a mechanism by which a gain in minimal luminal area occurs following balloon angioplasty. The presence of dissections is almost universal post percutaneous transluminal angioplasty and severe dissections predict poorer outcomes.⁵ Angiography is suboptimal in defining dissections, and IVUS is an important tool to identify their presence, extent, length, and depth.² Data suggest that deeper dissections are likely to lead to restenosis, while larger flaps commonly will compromise the acute results of a procedure. Repair of these dissections is possible with scaffolding, including stents or Tack implants. The latter has the distinct advantage of leaving less metal behind while effectively scaffolding the dissections. Data from TOBA II suggest that angiographic-based dissection repair leads to good outcomes, including improvement in patency and reduced target lesion revascularization, despite the use of DCBs or the severity of the angiographic dissection.⁶ In our case, the larger flap that was seen on IVUS, and which was grossly underappreciated on the angiogram, was the rationale behind repair with the Tack Endovascular System. 

Repairing dissections based on IVUS findings is an appealing concept. However, it is unclear which dissections should be repaired based on IVUS findings and whether repairing these dissections makes a difference in the overall outcome of a patient. Using the iDissection classification, we are more likely to see and treat large flap dissections (180 degree arc or wider) or deeper dissections (iDissection B and C grades). The rationale is based on the fact that acute procedural results may be compromised with larger flaps. Additionally, loss of patency may occur with deeper injury. Whether the long-term diminished effectiveness of DCBs is related to underappreciated significant dissections on angiography remains unclear. This concept awaits further validation. A randomized trial that includes IVUS would be needed to determine the threshold of dissection severity (whether arc and/or depth of injury) for dissection repair.

In conclusion, the presence of dissections is an inevitable consequence of angioplasty. Repairing these dissections appears to be a compelling concept. However, more research is needed to establish that repairing certain dissections seen on IVUS would improve acute and long-term patient outcomes.  

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Shammas receives educational and research grants from Intact Vascular, Phillips, Boston Scientific, VentureMed Group and Bard. John Shammas reports no conflicts of interest regarding the content herein.

Manuscript submitted May 17, 2019; accepted May 24, 2019.

Address for correspondence: Nicolas W. Shammas, MD, MS, EJD, FACC, FSCAI, FSVM, Midwest Cardiovascular Research Foundation, 1622 E. Lombard Street, Davenport, IA 52803. Email: shammas@mchsi.com

REFERENCES

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