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Aneurysm sac sealing a new and promising technique in endovascular aortic repair.

Introduction

Abdominal aortic aneurysm (AAA) rupture is a life-threatening medical emergency. From the 1950s, open surgical repair offered the only chance of survival but with it came with significant risk of complications. The evolution of endovascular aneurysmal repair using a transfemoral endoluminal approach and more recently the use of endovascular sealing device, currently undergoing clinical trial, offer new hope for patients with aortic aneurysm dissection or rupture. The development of treatment options is explored along with the role of Medical Imaging Nurses in interventional radiology suites.

An aneurysm is a localised, abnormal and permanent bulging or widening of a weakened segment of a blood vessel (Fournier, 2012). It is usually the normally elastic medial layer of the blood vessel that balloons out and causes an increase in diameter of the vessel to more than one and a half times its usual diameter. The abdominal aorta is one of the most common sites of aneurysm formation due to the constant pressure of blood flow through the abdominal vessel walls. Once an aneurysm starts, it will progressively increase in size and can therefore lead to sudden dissection or rupture. It has been considered as one of the most deadly pathologies with a slim chance of favourable surgical result (Wilton, 2012).

Abdominal aortic aneurysm formation is not always accompanied by symptoms. However, some people may complain of mild to severe pain or tenderness in the abdomen, chest or lower back. On physical examination AAA is described as a pulsating or throbbing mass in the abdomen. Routine physical examinations and diagnostic procedures such as computed tomography (CT) scans paved the way to incidental findings of AAA.

In the United States of America, 200,000 people are diagnosed with aortic aneurysm every year (Fournier, 2012). In New Zealand, 230 people died of AAA disease between 2002-2006. About 94 per cent of these patients are more than 65-years-old, are female and are Maori (Nair, Shaw, Sarfati & Stanley, 2012).

The Evolution of AAA treatment

The treatment of AAA has evolved dramatically over the years. One of the earliest procedures performed dates back in the 7th century (Wilton, 2012). The procedure involved filling the aneurysm sac with incense and spices to encourage formation of pus which was believed to encourage wound healing. In 1831, the lumen of the aneurysm was stuffed with sewing needles to promote thrombosis. In 1923, a procedure called endoaneurysmorraphy was performed by ligation of the aneurysm sac to restore the normal flow in the lumen, thus sparing the blood flow to the lower limbs. This procedure was later modified by using 26 yards of iron wire and eventually passing electric current through the wire, again to encourage thrombosis. This was known as the fili-galvanopuncture.

Wilton (2012) notes that in the 1940s the aneurysm sac was wrapped with cellophane to contain it and induce fibrosis, a procedure used to treat Albert Einstein in 1948. This effectively contained his aneurysm until 1955 when it finally ruptured.

In the 1950s the first AAA resection with restoration of arterial continuity was performed in France where a 51-year-old male patient received the aorta of a young girl. This became the foundation for synthetic aortic grafts. It was also around this decade that the first synthetic graft was inserted into a ruptured AAA. The material used was vinyon-N, the material used in parachutes. Eventually, similar procedures followed using nylon grafts and both the vinyon-N and nylon. In more recent years, the materials used for synthetic grafts include teflon, expanded polytetrafluoroethylene (PTFE), and dacron (Wilton, 2012).

The long and risky open surgical repair is the gold standard and was the only option for AAA treatment before the advent of endovascular aneurysm repair (EVAR) (Tinkham, 2013). It was regarded as a highly invasive procedure which excludes many patients for both medical and anatomical reasons. The procedure also carried a high risk of infection and bleeding. Argentinean Juan Parodi worked to rectify these issues with the aim of providing an alternative for open surgery, especially for vulnerable patients. He performed the first catheter-based arterial approach to AAA in Argentina in September 1990. He delivered a Dacron endograft mounted on a balloon-expandable stent using a transfemoral, endoluminal approach (Donayre et al., 2011). From then on, AAA has been successfully treated with minimally invasive procedures which avoid aortic cross-clamping and major abdominal surgery (Wilton, 2012).

The development of the Zenith Endovascular graft followed which was a key milestone in the development of endovascular aortic stent grafts of modern times. Then the implantation of the first bifurcated graft followed. Stent failures and complications become the basis for technical development of the grafts that followed. The aim of improving the grafts has been for better surgical outcome, prevention of complications, and inclusion of patients with unusual anatomy. Hence, devices with slimmer profiles emerged for access and treatment of tortuous vessels. Fenestrated and branched grafts were also made to cater to aneurysms below the renal artery to prevent complications such as renal failure and mesenteric ischaemia.

Endovascular aneurysm repair is now preferred over open surgical repair because it has significantly reduced operative mortality (Greenhalgh et al., 2010). Reimerink et al., (2013) recommend that EVAR be considered as the first-line treatment for ruptured AAA's due to the superior perioperative survival and decreased morbidity when compared to open repair.

EVAR is mostly performed through a cut-down or percutaneous access of one or both femoral arteries. Because it is less invasive, hospital stay is shorter. However, complications including persistent blood flow within the aneurysm sac (endoleaks) and the movement of the graft from the original deployment site (stent migration) require continued surveillance and re-interventions that prove to be costly (Greenhalgh, 2010).

Aneurysm Sac Sealing

Failure to treat endoleaks and stent migration can lead to return of the pressure on the artery wall and rupture of the aneurysm (Krievens et al., 2011). With the aim to address endoleaks and stent migration, the endovascular sealing (EVAS) concept was formed. The new device is made up of dual balloon-expandable endoframes for each iliac artery with polymer-filled endobags surrounding them (Donayre et al., 2011). The concept of the device is to treat the aneurysm lumen itself through sealing the aneurysm by filling the bags with polymers made of Polyethylene Glycol (PEG) Diacrylate Hydrogel which cures after three to five minutes (Bockler et al., 2014). When the bags are expanded, they provide positional stability and seal the side branch flow, preventing stent migration and endoleaks (Donayre et al., 2011). This device can be used to treat patients with favourable and adverse anatomy, thus accommodating more patients (Krievens et al., 2011).

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Early experience with his device outside of the Instructions for Use (IFU) also showed technical feasibility and promising short-term results (Bockler et al., 2014).

Auckland City Hospital in New Zealand--along with six other clinical centres in Europe--has experienced technical success in the deployment of the EVAS device (Bockler et al., 2015).

Dr Andrew Holden, Associate Professor of Radiology at Auckland City Hospital, is one of the principal investigators and was the first one to enrol a patient in the EVAS FORWARD-Global Registry. The first human deployment of this new device was in October 2013 with the hope of simplifying the procedure, improving end results for the patient and ultimately become the next gold standard for the treatment of AAA (Interventional News, 2013).

Involvement of Radiology Nursing Staff

Endovascular aneurysm repair in Auckland Hospital is performed in the Digital Subtraction Angiography (DSA) Suite. It is performed under general anaesthesia, by an interventional radiologist with a vascular surgeon on hand, should it proceed to an open repair. A radiographer and a medical company representative are also present during the procedure. A theatre nurse acts as a third nurse and two radiology nurses perform the scrub and circulating roles. The procedure may be done by performing a cut down on one or both groins. However, more percutaneous methods have been performed recently. Because of this and with the decreasing need to proceed to an open repair, EVAR procedures are performed more frequently in the DSA suites than in the operating theatre (Tinkham, 2009).

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The third nurse performs check-in as per the operative checklist, checks and confirms the patient position with the operators, inserts a urinary catheter, attaches an electro-surgical grounding pad on the patient and prepares both groins for access. They are also responsible for checking laboratory results, especially the creatinine level and renal function, due to large amounts of contrast injected during the procedure that may potentially result in nephrotoxicity.

The circulating nurse gathers equipment as per the recommended best practice list and prepares bags of heparinised saline for irrigation and flushing of catheters and wires during the procedure. The circulating nurse ensures equipment availability and opens it onto the sterile field as required. Equipment for conversion to open repair are on standby in the DSA suite. The scrub nurse keeps all wires and catheters clot-free by flushing them with heparinised saline and maintains the sterile field throughout the procedure. The scrubbing role had previously been shared between a radiology nurse and an operating room (OR) nurse. The OR nurse scrubbed for the cut-down and closing part of the procedure and the radiology nurse assisted in the radiology part of the procedure. However, in 2008, through collaboration with OR nurse educators, two radiology nurses rotated through the operating theatres for a month and learned to scrub for vascular cases. The aim was to orientate the two radiology nurses to scrubbing for the cut-down and closure part of the procedure. These two nurses in turn orientated their colleagues. Hence, only one nurse from theatre is now required during the procedure and performs the third nurse role.

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Conclusion

The durability of open surgical approach to AAA repair and the long-term results including high survival and minimal complication rate confirms that it is still the gold standard for treatment of patients with AAA (Sun, 2012). However, positive key outcomes from the EVAS FORWARD-Global Registry, which includes 289 patients, are promising including favourable fluoroscopy and procedure times, no device-related mortality, 1.1 per cent overall leak rate after one year follow up and overall device-related reinterventions of 1.1 per cent. These results suggest that the device has the potential to become the next gold standard for AAA repair (Endovascular Today, 2014) especially since enrolled patients included a broad range of aortic anatomies, 34 per cent of which would have been difficult to treat with other endovascular devices. However, long-term durability of this device is yet to be fully established (Holden, 2015).

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References

Bockler, D., Reijnen, M. M., Krievins, D., Peters, A. S., Hayes, P, & De Vries, J. P (2014). Use of the Nellix EVAS system to treat post-EVAR complications and to treat challenging infrarenal necks. The Journal of cardiovascular surgery, 55(5), 601-612.

Bockler, D., Holden, A., Thompson, M., Hayes, R, Krievins, D., de Vries, J. P R, & Reijnen, M. M. (2015). Multicenter Nellix EndoVascular Aneurysm Sealing system experience in aneurysm sac sealing. Journal of vascular surgery. doi: 10.1016/jjvs.2015.03.031

Donayre, C. E., Zarins, C. K., Krievins, D. K., Holden, A., Hill, A., Calderas, C., & White, R. A. (2011). Initial clinical experience with a sac-anchoring endoprosthesis for aortic aneurysm repair. Journal of vascular surgery, 53(3), 574-582. http://dx.doi. org/10.1016/j.jvs.2010.09.009

Endovascular Today. (2014). Endologix's Nellix shows very low endo leak rate in EVAS-FORWARD Global Registry. Retrieved February 23, 2015 from http:// evtoday.com/2014/11/initial-data-presented-from-evas-forward-global-registryfor-endologix-nellix-device

Fournier, M., & Zanoff, J. (2012). Understanding aortic aneurysms. OR Nurse 2014, 6(4), 26-34. Doi: 10.1097/01.0RN.0000415631.40932.14

Greenhalgh, R. M., Brown, L. C., Powell, J. T., Thompson, S. G., Epstein, D., & Sculpher, M. J. (2010). Endovascular versus open repair of abdominal aortic aneurysm. The New England journal of medicine, 362(20), 1863-1871. doi:10.1056/NEJMoa0909305

Holden, A. (2015). Endovascular sac sealing concept: will the Endologix Nellix[TM] device solve the deficiencies?. The Journal of cardiovascular surgery, 56(3), 339-353. Retrieved on February 23, 2015 from http://www.ncbi.nlm.nih.gov/ pubmed/25584735

Interventional News. (2013). First patient enrolled in EVAS Forward Global registry. Retrieved February 23, 2015 from http://www.cxvascular.com/in-latest-news/ interventional-news---latest-news/first-patient-enrolled-in-the-evas-forwardglobal-registry

Krievins, D. K., Holden, A., Savlovskis, J., Calderas, C., Donayre, C. E., Moll, F. L., & Zarins, C. K. (2011). EVAR using the Nellix Sac-anchoring endoprosthesis: treatment of favourable and adverse anatomy. European Journal of Vascular and Endovascular Surgery, 42(1), 38-46. doi: 10.1016/j.ejvs.2011.03.007

Nair, N., Shaw, C., Sarfati, D., & Stanley, J. (2012). Abdominal aortic aneurysm disease in New Zealand: epidemiology and burden between 2002 and 2006. Small, 433(1336), 2700. Retrieved February 23, 2015 from https://www.nzma.org.nz/ journal/read-the-journal/all-issues/2010-2019/2012/vol-125-no-1350/article-nair

Reimerink, J. J., Hoornweg, L. L., Vahl, A. C., Wisselink, W., van den Broek, T. A., Legemate, D. A., & Balm, R. (2013). Endovascular repair versus open repair of ruptured abdominal aortic aneurysms: a multicenter randomized controlled trial. Annals of surgery, 258(2), 248-256. doi: 10.1097/SLA.0b013e31828d4b76

Sun, Z.-H. (2012). Abdominal aortic aneurysm: Treatment options, image visualizations and follow-up procedures. Journal of Geriatric Cardiology: JGC, 9(1), 49-60. doi:10.3724/SP.J.1263.2012.00049

Tinkham, M. (2009). The Endovascular Approach to Abdominal Aortic Aneurysm Repair. AORN Journal, Volume 89, Issue 2, 289-306. http://dx.doi.org/10.1016/j. aorn.2008.11.028

Tinkham, M. (2013). Care of the endovascular aortic repair patient with endoleak. OR Nurse, Volume 7 Number 3, 32-40. Retrieved February 23, 2015 from http:// www.nursingcenter.com/cearticle?an=01271211-201305000-00009

Wilton, A.F. (2012). The history of abdominal aortic repair: from Egypt to EVAR. Australian Medical Student Journal, 3(2), 61-64. Retrieved February 23, 2015 from http://www.amsj.org/archives/2484

Diane Albao Taduran completed a Bachelor of Science in Nursing from Universidad de Sta Isabel in the Philippines in 2002 and her Post Graduate Certificate in Health Sciences: Advanced Nursing Specialisation from the University of Auckland in 2011. Her 13 years of nursing experience include medical-surgical ward and intensive care, clinical instruction, cardiac investigations and radiology. She has worked in the Radiology Department in Auckland Hospital from 2010.
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Title Annotation:medical imaging nursing
Author:Albao-Taduran, Diane
Publication:The Dissector: Journal of the Perioperative Nurses College of the New Zealand Nurses Organisation
Article Type:Report
Date:Sep 1, 2015
Words:2372
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