1Wythenshawe Hospital, Manchester University Hospitals NHS Foundation Trust (MFT), UK
2University of Manchester, UK
3NHS Health Education North West, UK
Received Date: 29/09/2020; Published Date: 02/10/2020
*Corresponding author: Christian Warner, Wythenshawe Hospital, Southmoor Road, Manchester,
Greater Manchester, M23 9LT, UK
We report a case of a 72-year-old female patient who presented with disabling short distance bilateral buttock claudication due to severe calcific stenosis of the infrarenal aorta. A balloon mounted stent graft was deployed to treat the aortic stenosis. During deployment of the stent graft, the balloon burst, and only partial retrieval was achieved via the introducer sheath. Surgical groin exploration was performed in order to remove the retained balloon fragment. Attempts to retrieve the balloon had caused an iliac artery dissection which was treated with a self-expanding stent insertion. The procedure was further complicated by distal embolism into the superficial femoral artery which was manage with surgical embolectomy.
Keywords: Deployment failure; Stent-graft; Angioplasty; Retrieval
Luminal narrowing of the aorta, or aortic stenosis, affecting the abdominal aorta is widely reported within literature despite being uncommon when compared to other aortic morphologies such as abdominal aortic aneurysms (AAA). In adults, abdominal aortic stenosis is often secondary to atherosclerotic disease. Other aetiologies include Takayasu arteritis, aortic dissection and iatrogenic secondary to intervention . Historically, bypass surgery or endarterectomy were the preferred treatment options for these patients. Towards the end of the last century however, percutaneous transluminal angioplasty (PTA) has been shown to be safe and effective [2,3]. Despite those early findings, there is a distinct lack of randomised controlled trials comparing therapeutic management over the last 30 years as a result of the relative rarity of these lesions . Due to their minimally invasive nature, endovascular treatments can be perceived as carrying a low or negligible risk. We would like to highlight a rare and unexpected complication of PTA in this case report which was successfully overcome.
A 72-year-old female presented with bilateral, very short distance, buttock claudication and lower back pain. Patient experienced symptoms on climbing single flight of stairs or walking less than 20 yards within her home. Past medical history included hypertension, hyperlipidaemia, CKD stage 3 and the patient is a non-smoker. Non palpable femoral or more distal pulses bilaterally. Unremarkable abdominal examination. Venous Duplex scan commented widely patent iliac arteries with reduced flow, monophasic signals in both common femoral arteries (CFA), superficial femoral arteries (SFA) and popliteal arteries with resting ABPIs of 0.49 bilaterally. CT Angiogram showed a severe focal stenosis of the infrarenal aorta approximately 3cm below renal arteries due to circumferential calcific atheromatous disease (Figure 1). The aorta was small in calibre, approximately 12mm. Distal to the aorta there were scattered calcifications present in the external iliac arteries with no focal stenosis. Bilaterally femoropopliteal and crural segment arteries were widely patent. A multidisciplinary team (MDT) decision recommended endovascular stenting of the infrarenal aorta using a covered balloon mounted stent graft.
Figure 1: Pre-Procedural CT Angiogram demonstrating severe focal stenosis of the infrarenal aorta approximately 3cm below renal arteries due to circumferential calcific atheromatous disease (left and centre) and three-dimensional rendering of this imaging modality (right).
The procedure was performed via a right common femoral artery approach under local anaesthesia. The infrarenal aortic stenosis was crossed and a 10 French long sheath advanced beyond the level of the stenosis (Figure 2). There was no pre-dilation of the vessel. A Bentley 12x59mm (un-sheathed) balloon mounted stent-graft was successfully deployed at its intended landing position (Figure 3), to protect the accessory renal artery and completion aortogram demonstrates good effect (Figure 4). During deployment of the stent graft, the balloon burst, on first inflation, at 10 atmospheres of pressure, below the rated burst pressure of 13 atmospheres (bar).
Figure 2: A single shot of a fluoroscopy loop acquired during balloon inflation shows the balloon at maximum point of inflation prior to bursting. The balloon has a uniform outline without a ‘kink’ which indicates suitable treatment of the stenosis.
Figure 3: (a): Identifying the level of the aortic stenosis using a hand injection of contrast via a cobra catheter inserted through a right common femoral artery approach.
(b): A 10Fr vascular access sheath has been placed beyond the stenosis. A digital subtraction angiography (DSA) contrast run clearly demonstrates position of renal arteries and tight flow limiting infra-renal aortic stenosis.
Figure 4: Completion aortogram following stent deployment in the infra-renal segment of the abdominal aorta.
It was not possible to retrieve the stent delivery mechanism percutaneously through the vascular access sheath. The balloon had become wedged just outside the sheath. With some traction of the balloon catheter over a stiff Amplatz type wire. The lower portion of the balloon, attached to the outer catheter (silver/clear) of the balloon, was removed. At this point operators realised that the balloon was split into two and one half was still remaining inside the patient over the wire.
Several attempts, including trial of removing the balloon through the right CFA without a sheath, were made to remove the remaining part of the balloon, however these were not successful. Following discussion with the vascular surgeons, a decision was made to retrieve the balloon surgically. The patient was informed, and gave verbal consent to a right groin exposure, exploration and proceed under general anaesthetic. A longitudinal incision was made to the right groin and the femoral vessels exposed. The remaining portion of the balloon and the sheath were removed under direct vision.
Upon analysis of the retrieved delivery system, it was clearly evident that the balloon had burst radially and failed to reduce in axial diameter enough to be fit through the lumen of the sheath (Figure 5 & 6). Following removal of the device and sheath, blood flow was poor. A further 2000 units of IV Heparin were given in addition to the previously administered 3000 units. Surgical embolectomy of the iliac inflow was performed using a size 4 Fogarty catheter, however the inflow remained poor. Angiogram showed dissection of the right external iliac artery. Therefore, percutaneous left CFA access was gained in order to access the true lumen. A wire was snared from the right groin and stenting of the right EIA was performed with a 7 x 60 mm self-expanding bare metal stent with good angiographic result (Figure 7). However imaging of the femoropopliteal segment showed thromboembolism into the superficial femoral (SFA) and profunda femoris (PFA) arteries. Subsequent surgical SFA and PFA embolectomies were performed to establish a good outflow (Figure 8 left and middle).
Figure 5: The tip of the vascular access sheath has been deformed by the ruptured balloon when attempts were made to retrieve the system.
Figure 6: Retrieval of delivery mechanism clearly shows it is in two parts. On the left is the majority of the balloon fragment on a blue delivery system. This had detached and remained within the patient creating the flow limiting dissection within the right external iliac artery. On the right is the lower end of the balloon that detached and was removed via the sheath along with the clear/silver delivery mechanism.
Figure 7: Right EIA dissection pre stenting (left) and post stenting (right).
Figure 8: Angiogram confirming absence of flow within the right SFA due to thromboembolism (left). Repeat angiogram following surgical embolectomy showing patent SFA and PFA (middle). Angiogram of the crural vessels showing patent crural vessels (right).
A right femoral endarterectomy was performed and the arteriotomy was then closed using a VascuGuard bovine pericardial patch with a running 6.0 proline suture. Immediately prior to this, a small flap in the proximal superficial femoral artery was tacked with a 7.0 prolene suture. On clamp removal, the final diagnostic angiogram revealed excellent flow within the right lower limb arteries (Figure 8 right). The patient experienced an uncomplicated recovery on the vascular surgery ward and was discharged home on day 3 post operation. They were started on Apixaban and Aspirin for the initial 6 weeks, then a 6-week regimen of dual antiplatelet therapy (clopidogrel and aspirin) and finally followed by long term clopidogrel only. The patient was followed up 6 weeks post-op and reported walking “unlimited distances”, compared to her previous short distance claudication. On examination the patient had palpable peripheral pulses and on handheld Doppler triphasic pedal signals with normal resting ABPI’s.
Focal infrarenal stenosis of the aorta is relatively uncommon and disproportionately affects women [5-7]. This classically presents with symptoms of bilateral claudication and is often also related to hypoplastic aortoiliac syndrome which can make surgical endarterectomy and bypass a more complex and challenging procedure with greater risks [7,8]. These patients are also typically younger and therefore more likely to require secondary intervention . As a result of the relative rarity of these lesions , there is a lack of randomised controlled trials comparing therapeutic management.
Primary stent placement is preferred over a surgical approach for its lower major complication and mortality rates, along with its shorter recovery period and when making consideration of potential secondary intervention in the future [5,8-10]. It also holds a an advantage over percutaneous transluminal angioplasty (PTA) for aortic disease, which was previously the low risk option for selected cases [8,11], due to the infrequent but associated risk of thrombus formation and restenosis, intimal dissection, acute aneurysm formation and rupture, and distal embolization with PTA alone [4,7-13]. For these reasons and results from several case series compared by Simons et al. demonstrating good patency rates it has been suggested as the first-line management for distal aortic occlusive disease since the early 2000s [5,9]. Stenting without predilation of the aorta reduces the risks of the PTA associated complications9 by preventing the elastic recoil of the vessel and associated stenosis and outward pressure between the intima and media layers .
Both bare and covered stents have been used for treatment of narrowing of the aorta, with each having their own relative drawbacks. Bare stents are reported to have a greater re-stenosis rate, whereas covered stents pose a greater risk of occlusion of the main branches of the abdominal aorta [11,12]. A preference for balloon mounted stents, and their greater radial force, are when calcified lesions are present in the vessel, which can be problematic when placing self-expanding stents and potentially lead to incomplete deployment or create difficulty advancing balloon catheters into the stent after deployment . This is the rationale of using a balloon mounted stent graft in our case. However, a recognised fallibility of balloon mounted stents is their susceptibility to compression and deformation which was observed early in their use . Rupture of the delivery balloon and vascular damage using balloon-mounted stents is suggested due to be to the more rigid nature of the stent itself [11,13] and correlated to the relative lengths of the balloon and stent in use . Self-expanding stents comparatively result in fewer incidences of damage against the vessel wall, however are more difficult to site and prone to “jumping” on deployment [11,12].
Horton et al. present their findings of sharp vascular calcifications causing recurring and reliable balloon rupture with apparent abrasions and focal puncture point during their embolization procedures . Blame has often been ratified on the irregularities of the vessel, be it a calcified or angular lesion or tortuous vessel or technical factors such as over inflation of balloon pressure, or subsequent incomplete deflation, in cases of retention or entrapment of the balloon portion of devices [17-19].
The authors present a case where a balloon mounted stent graft was used to treat a focal infra-renal aortic stenosis. The post procedure results were satisfactory with good clinician and patient reported outcome measures at 6 weeks follow up. Despite following national guidelines, we experienced an expected and potentially severe complication which was rectified with a multidisciplinary approach. At our local hospital, all endovascular aortic work is performed in close collaboration with the interventional radiology, vascular surgery and anaesthetic departments, as well as the manufacturing companies. We believe it is this safety infrastructure that allows for the timely evaluation and action of any potential problems that may arise during the procedure.
Our case was reported to the manufacturer and the summary of their investigation was the severity of the calcification at the point of deployment caused the balloon to burst . Though not a novel finding in itself, it was the mechanism of burst which led to the complications experienced and outlined in this report. A detailed review by the manufacturer (Bentley) follows below. In an overview statement, the company said “[The] product was produced within the defined specifications…The lot passed all in-process controls…as well as the determination of the balloon burst pressure and burst mode… A device malfunction is not assumed but cannot be completely excluded.”
The balloons are designed to burst longitudinally in the event of a burst of up to three atmosphere (ATM) above rated burst pressure (RBP) for this balloon diameter. Above three ATM they can also burst radially. It is not known at which pressure the balloon bursts and what the burst mode looks like, though it appears to be longitudinal and radial (Figure 9). The failure mode occurred most probably due to a damage during use and an interaction with difficult anatomical conditions (heavy calcification). Therefore, the most probably root cause of the burst balloon is the inflation of the balloon in the severe calcified lesion.
As part of a review of the case we identified that the ultimate management was suitable and in following with the literature. The authors acknowledge however, that such invasive methods of retrieval should only be used when absolutely necessary and in future, retrieval using a snare from the top of the balloon or contralateral side would be attempted in the first instance.
Figure 9: BeGraft Aortic balloon catheter fragments. The main part of the balloon is still attached to the inner tubing and a small part to the outer tubing. A statement from Bentley said: “The split of the balloon was found not to be at the tip of the catheter but in the proximal balloon cone…the main balloon part is still attached to the inner tubing (at the catheter tip). The guide wire is stuck in the guide wire lumen of the inner tubing.
PTA has established itself as the preferred method of treatment for focal infrarenal aortic stenosis. Balloon rupture is a potentially dangerous complication that may occur, and endovascular retrieval is not always possible. Clinicians must be aware of the different balloon burst mechanisms, and how to identify and manage them.
Informed consent has been obtained from the patient for publication of the case report and accompanying images.
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
The author(s) received no financial support for the research, authorship, and/or publication of this article.