Integrating Intravascular Lithotripsy to Overcome Severe Aorto-Iliac Atherosclerosis in Standard Endovascular Aortic Repair: A Case Report

Abstract

Introduction

Endovascular aneurysm repair (EVAR) is a safe and widespread treatment option for abdominal aortic aneurysm (AAA). Unfavourable anatomy, such as hostile neck and aorto-iliac atherosclerosis, can lead to many complications and compromise the long term reliability of the endograft, resulting in a high rate of EVAR failure. Intravascular lithotripsy (IVL) has emerged as an alternative treatment to address severe iliofemoral atherosclerosis, aiding trackability of devices in EVAR. However, the use of IVL to address severe calcification in hostile necks has not yet been described.

Report

A 74 year old man with multiple comorbidities was referred for definitive treatment of an asymptomatic infrarenal AAA with severe aorto-iliac atherosclerosis. Kissing lithotripsy was firstly performed to treat the calcified stenosis of the aortic bifurcation and iliac axes. To prevent infolding and type Ia endoleak (ELIa), IVL was also performed through simultaneous inflation of two IVL balloon catheters and a compliant aortic balloon on a conical shape neck with an eccentric calcified plaque. The procedure was completed with standard EVAR. The three month follow up computed tomography angiography confirmed a successful outcome with shrinkage of the excluded aneurysmal sac, patent iliac axes, and complete disruption of the severe eccentric calcification of the aortic neck with no signs of infolding or endoleak.

Discussion

This case report highlights the potential of IVL to improve the proximal sealing zone, prevent infolding and ELIa, enhance trackability of devices, reduce major complications, and extend the application of standard EVAR in patients with challenging anatomy. However, further studies and long term follow up are needed to define the efficacy and safety of integrating IVL in standard EVAR.

INTRODUCTION

Endovascular aneurysm repair (EVAR) is a widely accepted alternative to open surgical repair (OSR) for abdominal aortic aneurysm (AAA) and is the first line treatment for frail patients with suitable anatomy.¹ Unfavourable anatomy, such as hostile neck and aorto-iliac atherosclerosis, has been documented in 40–60% of AAA cases.² After EVAR, these conditions can lead to complications and compromise the long term reliability of the endograft, resulting in a high rate of failure.³ Although there is no unanimously accepted consensus on the characteristics of a hostile aortic neck, stenotic aortic bifurcation and severely calcified iliac axes are relative contraindications to EVAR and may lead to endograft limb occlusion.^4,5 In diffuse calcified iliac arteries, vessel compliance is very poor, and such stiffness can compromise the trackability of devices and large aortic endografts, exposing the artery to local complications such as rupture, dissections, and or occlusions.⁵ Currently available options to overcome this issue include pre-EVAR angioplasty of the common and external iliac artery stenosis or the paving and cracking technique, where covered stents are placed in the iliac arteries, followed by aggressive dilatation with non-compliant balloons.^5,6 However, this approach carries a high risk of rupture, dissection, and stent fracture within highly calcified arteries.⁵

Instead of conventional angioplasty or atherectomy, intravascular lithotripsy (IVL) has emerged as an alternative treatment option for severely calcified lesions.^4,5 Ultrasonic waves induce microfractures in calcified plaques, acting in both the intimal and medial layers without injuring the vessel and enhancing vessel compliance.^4,5 It has been proven to be effective in treating highly calcified occlusive diseases in both the coronary and peripheral arteries and in facilitating transfemoral trackability of devices in thoracic endovascular aortic repair and EVAR; however, the use of IVL to address severe calcification in hostile necks has not yet been described during EVAR.⁴

CASE REPORT

A 74 year old man was referred to the Department of Vascular Surgery for definitive treatment of an infrarenal AAA followed up for five years. The AAA was discovered incidentally during diagnostic work up for cardiac arrest caused by vasculitic cardiac tamponade, which was promptly treated with pericardiotomy. Computed tomography (CT) of the chest and abdomen demonstrated a fusiform infrarenal AAA with a maximum diameter of 60 mm that extended to the aortic bifurcation (Fig. 1A). The aortic bifurcation and iliac arteries presented with severe calcific stenosis. In particular, the patent lumen of the left common iliac artery was 3.6 mm with 70% stenosis (Fig. 1C). Furthermore, the aortic neck was hostile due to its conical morphology and severe circumferential calcification exceeding 50% (Fig. 1B). General anaesthesia was contraindicated due to the patient's multiple comorbidities: smoking, hypertension, dyslipidaemia, chronic pancreatitis, chronic obstructive pulmonary disease, and significantly reduced cardiac reserve. Therefore, OSR was not deemed feasible, leaving EVAR as the last available option. Given the high risk of inadequate proximal sealing, limb graft occlusion, and compromised trackability of the devices due to widespread atherosclerosis, pre-emptive vessel preparation with IVL was planned.

Figure 1.

Pre-operative images of the infrarenal aortic aneurysm. A. 3D computed tomography reconstruction. B. Hostile aortic neck characterised by a severe eccentric plaque and conical morphology. C. Severe atherosclerosis of the iliac arteries with significant calcific component, resulting in a pre-occlusive state at the aortic bifurcation.

Procedure

Ultrasound guided access of the right common femoral artery (CFA) and surgical access of the left CFA were performed. Two Perclose ProStyle systems (Abbott, Chicago, IL, USA) were pre-implanted on the right side of the groin. Bilaterally, two 8F sheaths were positioned in the CFA. Catheter aortography through the right access confirmed severe calcification of the aortic neck, severe stenosis of the aortic bifurcation and iliac arteries, and occlusion of both hypogastric arteries. Pre-dilatation with 5 mm plain balloon angioplasty was first performed on the left iliac axis, which was the site of major stenosis. Two 8 mm x 60 mm Shockwave M5+ IVL balloon catheters (Shockwave Medical Inc., Santa Clara, CA, USA) were inflated side by side using the kissing balloon angioplasty technique (e.g., kissing lithotripsy). Both balloon catheters were initially inflated at low pressure (4 atm) for three treatment cycles, after which the pressure was increased to nominal (6 atm) for two additional treatment cycles (Fig. 2A). Intravascular lithotripsy was also performed on the aortic neck with five treatment cycles through simultaneous inflation at nominal pressure (6 atm) of two 8 mm x 60 mm Shockwave M5+ IVL balloon catheters and a Reliant Stent Graft Balloon Catheter (Medtronic, Dublin, Ireland) (Fig. 2B). The rationale behind Reliant inflation was to occupy the residual area of the aortic lumen and ensure direct contact between the two IVL balloon catheters and the aortic wall. Post-IVL angiography revealed improved iliac patency. The 8F sheaths were upsized to an 18F sheath on the right access and a 14F sheath on the left one. The endovascular procedure was successfully completed by deployment of a Medtronic Endurant IIs main body (ESBF2814C103EE) and ipsilateral limb (ETLW1610C124EE) from the right sheath and the contralateral limb (ETLW1613C124EE) from the left one; both landing zones were positioned just proximal to the iliac bifurcation (Medtronic). Final angiography revealed an absence of endoleak (EL) (Fig. 2C). The right access was closed using the previously implanted ProStyle sutures. The left CFA was surgically closed after sheath removal.

Figure 2.

Pre-emptive intravascular lithotripsy and standard EVAR. A. Kissing lithotripsy with simultaneous inflation of two 8 mm x 60 mm Shockwave M5+ IVL balloon catheters. B. Pre-emptive intravascular lithotripsy of aortic neck through simultaneous inflation of two 8 mm x 60 mm Shockwave M5+ IVL balloon catheters and a Reliant Stent Graft Balloon Catheter. C. Final control intra-operative angiogram with no signs of endoleaks and patent endograft.

Follow up and outcome

The post-operative course was complicated by lymphorrhoea from the left groin wound. The patient was discharged home on post-operative day 7 with no complaints of claudication, ischaemic rest pain, or abdominal and back discomfort. At one month, aorto-iliac duplex ultrasound (DUS) demonstrated patency of the endograft and the absence of EL. The three month CT angiography (CTA) follow up confirmed the appropriate placement of the endograft and shrinkage of the aneurysm sac (Fig. 3A). The optimal proximal sealing zone was achieved with complete disruption of the severe eccentric calcification of the aortic neck (Fig. 3B and C). The iliac axes were widely patent bilaterally without evidence of aneurysmal dilatation or significant residual stenosis (Fig. 3D). Additionally, there was no evidence of EL.

Figure 3.

Three month follow up computed tomography angiography. A. Post-operative 3D computed tomography angiography reconstruction. B and C. Optimal proximal sealing zone with complete disruption of the severe eccentric calcification in the aortic neck. D. Iliac axes widely patent bilaterally without evidence of aneurysmal dilatation or significant residual stenosis.

DISCUSSION

Although EVAR is generally associated with reduced early morbidity and mortality, the long term durability of implants relies on maintaining endograft patency and ensuring sealing between the endograft, aortic neck, and iliac arteries.^1,2 In a multicentre observational study involving 10 228 patients, only 41% of EVAR were performed within the device's instruction for use, leading to a high rate of failure due to the presence of unfavourable anatomical factors such as aorto-iliac atherosclerosis and hostile neck configurations.1, 3 Despite limited evidence in the literature regarding the definition of a hostile neck and its role in type Ia endoleak (ELIa), re-operation rates and aneurysm related mortality, a recent Delphi Consensus based on 66 studies identified five anatomical parameters (listed in Table 1), that are associated with increased risk of peri-operative and post-operative complications.2, 4 Table 1 provides specific thresholds for the risk of failure of standard EVAR for each criterion, as well as for a combination of at least two criteria.² Given these considerations, this case presented significant challenges. The extensive aorto-iliac atherosclerosis and severely calcified conical aortic neck prompted a multidisciplinary assessment to evaluate the surgical risk of OSR. Due to the patient's compromised respiratory function and significantly reduced cardiac reserve, both general anaesthesia and OSR were contraindicated by the high risk of complications and death, leaving endovascular treatment as the only viable option. According to the latest Delphi consensus, a standard EVAR procedure in such challenging cases has a moderate risk of failure.² Alternative procedures such as Chimney EVAR or a custom fenestrated EVAR were not considered to be viable options due to the high risk of graft infolding and occlusion of the bridging stents.

Table 1.

Aortic neck hostility classification and degree of consensus regarding the risk of technical failure in standard EVAR.²

	Neck length 11–15 mm	Neck length 4–10 mm	Neck width >28 mm	Neck angulation 60–74°	Neck angulation ≥75°	Calcification ≥50%	Conical neck
Neck length 11–15 mm	0	N/A	56	67	67	33	33
Neck length 4–10 mm	N/A	100	100	100	100	100	100
Neck width >28 mm	N/A	N/A	56	78	78	78	67
Neck angulation 60–74°	N/A	N/A	N/A	67	N/A	78	78
Neck angulation ≥75°	N/A	N/A	N/A	N/A	67	78	78
Calcification ≥50%	N/A	N/A	N/A	N/A	N/A	33	67
Conical neck	N/A	N/A	N/A	N/A	N/A	N/A	33

Data are shown as %.

N/A: Not applicable.

Given the team's experience with IVL for iliofemoral occlusive disease, it was decided to use this technique on the aortic neck in order to mitigate the risk of infolding and ELIa. Using software reconstruction on centreline (Aquarius Intuition; TeraRecon), an area assessment of the hostile neck was performed, revealing a patent lumen area of 2.78 cm² and an overall aortic area of 4 cm² (Fig. 2). Since lithotripsy balloon catheters >8 mm are unavailable (the calculated area of the IVL balloon catheter at nominal pressure was 0.5 cm²), an additional compliant balloon was inflated to ensure that the lithotripsy devices made adequate contact with the arterial walls. As the final part of the pre-operative planning, DUS of the femoral access, confirmed by the available CT images, revealed extensive calcification of the left CFA. Due to the high risk of percutaneous closure system failure and potential arterial damage leading to haemorrhage, an elective surgical approach to the left CFA was preferred.

Conclusions

This case report highlights the potential of IVL to improve the proximal sealing zone, prevent infolding and ELIa, and enhance trackability of devices without resulting in rupture, perforation, or dissection of the vessels. Based on the literature review and surgical experience, IVL may be considered a promising and safe solution to address the challenges posed by highly calcified aortic necks and iliac axes, potentially expanding the application of standard EVAR in patients with similar anatomical challenges. However, further studies and long term follow up are warranted to define the efficacy and safety of integrating IVL into standard EVAR.

FUNDING

This research received no grant from any funding agency in the public, commercial or not-for-profit sectors.

CONFLICT OF INTEREST

None.