Zachary M. Arthurs

Functional Outcome after Resuscitative Endovascular Balloon Occlusion of the Aorta of the Proximal and Distal Thoracic Aorta in a Swine Model of Controlled Hemorrhage

BACKGROUNDnNoncompressible torso hemorrhage remains an ongoing problem for both military and civilian trauma. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has been characterized as a potentially life-saving maneuver. The objective of this study was to determine the functional outcomes, paraplegia rates, and survival of 60-min balloon occlusion in the proximal and distal thoracic aorta in a porcine model of controlled hemorrhage.nnnMETHODSnSwine (Sus scrofa, 70-110 kg) were subjected to class IV hemorrhagic shock and underwent 60 min of REBOA. Devices were introduced from the left carotid artery and positioned in the thoracic aorta in either the proximal location (pREBOA [n = 8]; just past takeoff of left subclavian artery) or distal location (dREBOA [n = 8]; just above diaphragm). After REBOA, animals were resuscitated with whole blood, crystalloid, and vasopressors before a 4-day postoperative period. End points included evidence of spinal cord ischemia (clinical examination, Tarlov gait score, bowel and bladder dysfunction, and histopathology), gross ischemia-reperfusion injury (clinical examination and histopathology), and mortality.nnnRESULTSnThe overall mortality was similar between pREBOA and dREBOA groups at 37.5% (n = 3). Spinal cord-related mortality was 12.5% for both pREBOA and dREBOA groups. Spinal cord symptoms without death were present in 12.5% of pREBOA and dREBOA groups. Average gait scores improved throughout the postoperative period.nnnCONCLUSIONSnREBOA placement in the proximal or distal thoracic aorta does not alter mortality or paraplegia rates as compared with controlled hemorrhage alone. Functional recovery improves in the presence or the absence of REBOA, although at a slower rate after REBOA as compared with negative controls. Additional research is required to determine the ideal placement of REBOA in an uncontrolled hemorrhage model to achieve use compatible with survival outcomes and quality of life.

Endovascular Management of a Mobile Thoracic Aortic Thrombus Following Recurrent Distal Thromboembolism: A Case Report and Literature Review

Sources of lower extremity and visceral arterial thromboembolism most commonly include the heart and proximal aneurysmal disease. Infrequently, further workup of “cryptogenic” emboli will reveal a mural atheroma or thrombus of the descending thoracic aorta. Without prospective data, anticoagulation and open surgical thrombectomy with or without aortic replacement have been the standard approach. Presented is a case of a floating mural thrombus in the setting of superior mesenteric and femoral arterial thromboembolism that was effectively treated with endovascular stent graft exclusion.

Mechanism of Stent Failure in a Patient with Fibromuscular Dysplasia following Renal Artery Stenting

Endovascular techniques used in the management of renal artery stenosis (RAS) have unique complications, to include stent facture, thrombosis, aneurysm formation, migration, and in-stent restenosis. Described here is an unusual complication of renal artery obstruction and recurrent hypertension without progressive loss of renal function, secondary to intermittent arterial kinking with respiratory and cardiac motion in a patient with fibromuscular dysplasia. This mechanical complication has implication not only in successful endovascular treatment of RAS, but raises questions regarding the alterations in dynamic motion with the cardio-respiratory cycle in stented visceral arteries in other vascular pathologies requiring renal artery stenting (i.e., juxtarenal or pararenal aortic aneurysms).

A Diagnostic Evolution: Surgical Experience with Popliteal Artery Entrapment Syndrome at a Military Tertiary Referral Center

BACKGROUNDnPopliteal artery entrapment syndrome (PAES) is an increasingly encountered disorder that typically presents as claudication in young and active individuals. However, despite the increased recognition, accurate preoperative diagnosis can be difficult. The objective of this study was to describe the surgical assessment and outcomes of patients treated for PAES.nnnMETHODSnRetrospective case series of all patients managed surgically for a diagnosis of PAES at the San Antonio Military Medical Center from 2005 to 2013.nnnRESULTSnOver 8 years, PAES was surgically treated in 25 consecutive limbs of 15 patients (mean age, 35; range, 21-49) in a military tertiary medical center. Type III was the most common variant (n = 13, 52%), followed by type VI (n = 7, 28%). Most patients presented with class I or II ischemia (88%), with anterolateral symptoms (56%), and were referred by orthopedics (66%). Diagnostic work-up included stress ankle-brachial indices, magnetic resonance imaging (MRI) and provocative angiography. Sixty-three percent of limbs with negative MRI demonstrated findings consistent with either type III or V PAES. Tendon release was used in those with types III and V, whereas liberal myectomy was used in those with types I, II, or VI. Two patients required revascularization. At a median follow-up of 126 days (range, 25 days-7 years), 83% of patients with type III demonstrated partial resolution of symptoms. Only 27% of patients without an identifiable muscle slip had clinical improvement.nnnCONCLUSIONSnDespite modern imaging, open surgical exploration remains the definitive diagnostic modality for PAES. Patients with a muscular or tendinous slip identified intraoperatively have the best clinical outcomes. Those with no identifiable muscle slip (functional entrapment) are less likely to demonstrate clinical improvement. Further evaluation on outcomes in the management in PAES is warranted.

Prosthetic Graft Patency in the Setting of a Polymicrobial Infection in Swine (Sus scrofa)

BACKGROUNDnIn the setting of vascular injury, vein interposition graft is the preferred conduit, but may have limited availability. This study seeks to develop a large animal model assessing the graft performance of polytetrafluoroethylene (PTFE) and Dacron in the setting of a polymicrobial infection.nnnMETHODSnThirty-seven animals were placed into 4 groups for a 21-day survival period. Six-millimeter PTFE or Dacron interposition grafts were placed in the right iliac artery with a standardized bacterial inoculation. Native vessel with and without contamination served as control groups. The inoculant was 1 × 107 of genetically labeled Pseudomonas aeruginosa and Staphylococcus aureus. The primary end points were graft patency (determined by duplex ultrasound and necropsy) and graft infection (culture with molecular analysis). Secondary end points included physiological measurements, blood cultures, laboratory data, and histopathology.nnnRESULTSnPTFE and Dacron had similar infection rates of 85.7% and 75%, respectively. There was no significant difference in infectious organisms between graft materials. PTFE and Dacron exhibited bacterial ingrowth and transmigration to the intraluminal portion of the conduit. Forty-five percent of the Dacron group and 40% of the PTFE group remained patent at postoperative day 21 (Pxa0=xa00.98). Clinical data, including white blood cell count, percent neutrophils, and lactate, did not vary significantly between groups.nnnCONCLUSIONSnPTFE and Dacron perform similarly in terms of infection rates and graft failure as both have a propensity toward bacterial ingrowth and occlusion when compared with controls. This is a valid animal model to assess graft performance in the setting of polymicrobial infection and provides an avenue for studying novel prosthetic conduits.

A technique for endograft relining of a type IV endoleak using a surgeon-modified internal gate.

Type IV endoleaks represent a rare etiology of late endograft failure; however, depending on the location, they can be extremely challenging to repair with endovascular solutions. We present a method of endograft relining that preserves antegrade limb perfusion, avoids extra-anatomic reconstructions, and ensures complete endograft exclusion.

Magnetic resonance imaging: occult popliteal artery entrapment syndrome in a young soldier.

BACKGROUNDnPopliteal artery entrapment syndrome (PAES) is frequently misdiagnosed because of symptom overlap with other conditions and lack of a definitive diagnostic modality. The incidence is widely variable, although it should be considered in all patients under 50 years with symptoms of lower extremity claudication. Long-term sequelae of PAES include critical limb ischemia, arterial occlusion, and aneurysm formation caused by repetitive external compression.nnnMETHODSnWe review the case of a 27-year-old soldier originally treated for exertional compartment syndrome with fasciotomies without relief of symptoms. Magnetic resonance imaging (MRI) failed to demonstrate an aberrant slip of the gastrocnemius muscle, which was ultimately found and released on surgical exploration.nnnRESULTSnSurgical exploration and release of an aberrant band of gastrocnemius muscle through a medial approach resulted in significant relief of symptoms and improvement of walking distance.nnnCONCLUSIONSnHealthy athletes without peripheral vascular disease and symptomatic calf and foot claudication should have an early referral to vascular surgery. The risk of false-negative MRI warrants further investigation into provocative, noninvasive imaging modalities to properly classify PAES. This report reviews the literature to discuss the diagnostic challenges, natural history of disease, and surgical interventions for PAES.

Endovascular Aortoiliac Reconstruction to Allow Excision of an Infected Axillobifemoral Bypass

Axillofemoral graft reconstructions were initially intended to restore lower extremity perfusion in high-risk patients with symptomatic aortoiliac atherosclerotic occlusive disease. However, these reconstructions are now relegated to bailout procedures for infected grafts or high-risk critical limb ischemia patients that fail endovascular therapy. Infection of an extra-anatomic bypass graft is a challenging complication as it occurs in poor operative candidates with limited revascularization options and failure has a high rate of amputation and mortality. Described is a novel approach using endovascular reconstruction to treat symptomatic Trans-Atlantic Inter-Society Consensus-II type D aortoiliac lesions allowing for complete excision of an infected axillobifemoral bypass.

Successful Use of Nellix and Endovascular Aortic Sealing Technology for Treatment of Aortic Rupture in a Porcine Model

BACKGROUNDnEndovascular aortic sealing (EVAS) represents a recent transformation in approach for treatment of aortic aneurysms. Initial reporting has shown that EVAS using the Nellix device is safe with similar complication rates to standard endovascular aortic repair (EVAR). What remains unknown is how EVAS technology will behave in the ruptured setting. The purpose of this report is to discuss how EVAS system and endobag technology behave when deployed in a porcine model of aortic rupture.nnnMETHODSnA controlled left retroperitoneal rupture was created in 20 large swine. Following rupture, an EVAS system was deployed across the rupture site to seal the area. The primary end point was seal from ongoing hemorrhage. Other parameters were examined to include endobag extravasation, aortic wall pressure measurements and device behavior in a live tissue model.nnnRESULTSnOf the EVAS systems used, 15 Nellix (Endologix, Irvine, CA) devices and 5 novel EVAS systems were used. Of the correctly deployed devices, 100% sealed the rupture (nxa0=xa019). One device was deployed above the rupture site, and seal was not achieved secondary to malpositioning. Endobag extravasation was seen with an average protrusion of 7.7xa0mm. No other areas of aortic injury were noted secondary to endobag trauma. Pressure recording from behind the endobag indicates loss of pulsatile flow to the aortic wall with polymer curing.nnnCONCLUSIONSnEndovascular aortic sealing for rupture is feasible and performs well in a porcine model of aortic rupture. Polymer extravasation is seen and may be controllable by the implanter. Once the polymer has cured, pulsatile aortic wall pressure is no longer present. EVAS represents an emerging technology for treatment of aortic rupture.

Ruptured Abdominal Aortic Aneurysms: Aortic Occlusion Balloons

Achieving rapid and effective control of the aorta remains a fundamental concept for salvaging ruptured abdominal aortic aneurysm patients. The degree of hemorrhage and patient comorbidities dictate how long a patient can survive before cardiac collapse. One of the major barriers to treating unstable ruptured aneurysms with endovascular therapy is the ability to achieve hemorrhage control while excluding the aneurysm with a stent graft. Aortic occlusion balloons can be deployed in a simple, rapid, and effective manner to achieve hemodynamic stability. This technique can be utilized for both open and endovascular repair of ruptured abdominal aortic aneurysms.