Martyn Knowles

Volumetric analysis of type B aortic dissections treated with thoracic endovascular aortic repair

BACKGROUND Type B aortic dissections are being successfully treated by thoracic endovascular aortic repair (TEVAR). Postoperative false lumen patency has been associated with aneurysmal dilatation and rupture of the thoracic aorta, necessitating further intervention. This is the first volumetric analysis of type B aortic dissections comparing patients with and without false lumen thrombosis (FLT) after TEVAR. We hypothesized that a greater increase in postoperative true lumen volume will lead to FLT, and without this change, false lumen patency will result. METHODS Preoperative and postoperative computed tomography angiography (CTA) imaging was analyzed using three-dimensional reconstruction to measure the short- and long-axis diameter and cross-sectional area of the true lumen, false lumen, and total aorta. Measurements were taken at 5-cm intervals from the left subclavian artery to the aortic bifurcation. Pre- and postoperative volumetric data were calculated and compared in patients with and without postoperative FLT. RESULTS Between 2006 and 2010, 132 patients underwent thoracic aortic stent grafting. Of these, 31 (23%) had thoracic endografting for type B aortic dissection. Pre- and postoperative CTA images were available for analysis in 23 patients with a mean age of 59 ± 14 years treated for acute, complicated (n = 8, 35%), and chronic (n = 15, 65%) indications. Mean follow-up imaging was 9 months (range, 1-39 months). Thirteen patients (56%) had postoperative FLT and 10 (43%) had persistent false lumen patency. The dissections involved the left subclavian artery (n = 12), visceral arteries (n = 14), renal arteries (n = 16), and iliac arteries (n = 15). The left subclavian artery was intentionally covered in 15 patients (65%). There were no significant differences in age, acute vs chronic dissection, branch vessel involvement, coverage of the left subclavian artery, or distal extent of the endograft between patients with and without postoperative FLT. Patients with postoperative FLT had a significantly smaller preoperative maximum thoracic aortic diameter (5.05 ± 1.0 vs 6.30 ± 1.4 cm; P = .02). Volumetric analysis demonstrated significantly smaller preoperative true lumen volume (141.3 ± 68 vs 230.5 ± 92 cm(3); P = .01) in patients with FLT, but no difference in preoperative false lumen volume. Patients with FLT had a significant increase in the volume percentage of the true lumen from 42.7% to 61.7% (P = .02) after stent graft repair, compared with an increase from 46.7% to 47.7% (P = .75) in patients with persistent false lumen patency. CONCLUSIONS This volumetric study of type B aortic dissection treated with TEVAR suggests that the ability of the endograft to significantly increase the true lumen volume as a percent of the total aorta most accurately predicts postoperative FLT. This is best demonstrated in a nonaneurysmal dissection regardless of timing since dissection.

Ruptured splenic artery aneurysms are exceedingly rare in pregnant women.

OBJECTIVE Pregnancy is cited as the most important risk factor for splenic artery aneurysm (SAA) rupture, but the true rupture rate of SAAs during pregnancy is unknown. Our objective was to evaluate the prevalence of SAAs, based on diagnostic and procedural codes, in an urban population treated in a county hospital with the highest number of births in the United States. We hypothesized that SAA rupture in pregnant women is very low and that SAAs are more likely to be diagnosed in older patients. METHODS Patients diagnosed with a SAA during a recent 5-year period were identified using International Classification of Diseases-Ninth Edition, Clinical Modification, and Current Procedural Terminology (American Medical Association, Chicago, Ill) codes. Demographics, imaging, and risk factors for rupture were reviewed. RESULTS We identified 35 patients with SAA. Patients were a median age of 63 years (interquartile range [IQR], 54-74 years), and 28 (80%) were women who were a median age of 62 years (IQR, 54-74 years). The SAAs in the 35 patients were a median size of 1.3 cm (IQR, 1-1.9 cm), and eight (23%) were >2 cm. Despite the very large number of deliveries recorded during the study period (67,616 births), no women who were pregnant or aged <45 years were identified. However, 89% of women with an SAA had previous pregnancies. Two women and one man (8.6%) experienced rupture, resulting in one death (2.9%). More than one imaging study was available for 19 patients (60%) without intervention for a median of 32 months (IQR, 7-76 months), with no significant change noted. Three patients underwent elective repair due to size criteria. Six patients (17%) had concurrent aneurysms, including three renal artery aneurysms, one aortic aneurysm, and three intracranial aneurysms. No risk factor for enlargement or rupture was particularly prevalent. CONCLUSIONS Ruptured SAAs are exceedingly rare in young women, and no ruptured SAA were identified during pregnancy in this study. SAA are frequently diagnosed as an incidental finding in middle-aged adults and tend to remain stable over time in this population.

Upper Extremity Access for Fenestrated Endovascular Aortic Aneurysm Repair Is not Associated with Increased Morbidity

OBJECTIVE Fenestrated endovascular aortic aneurysm repair (FEVAR) is an alternative to open repair in patients with complex abdominal aortic aneurysms who are neither fit nor suitable for standard open or endovascular repair. Chimney and snorkel grafts are other endovascular alternatives but frequently require bilateral upper extremity access that has been associated with a 3% to 10% risk of stroke. However, upper extremity access is also frequently required for FEVAR because of the caudal orientation of the visceral vessels. The purpose of this study was to assess the use of upper extremity access for FEVAR and the associated morbidity. METHODS During a 5-year period, 148 patients underwent FEVAR, and upper extremity access for FEVAR was used in 98 (66%). Outcomes were compared between those who underwent upper extremity access and those who underwent femoral access alone. The primary end point was a cerebrovascular accident or transient ischemic attack, and the secondary end point was local access site complications. The mean number of fenestrated vessels was 3.07 ± 0.81 (median, 3) for a total of 457 vessels stented. Percutaneous upper extremity access was used in 12 patients (12%) and open access in 86 (88%). All patients who required a sheath size >7F underwent high brachial open access, with the exception of one patient who underwent percutaneous axillary access with a 12F sheath. The mean sheath size was 10.59F ± 2.51F (median, 12F), which was advanced into the descending thoracic aorta, allowing multiple wire and catheter exchanges. RESULTS One hemorrhagic stroke (one of 98 [1%]) occurred in the upper extremity access group, and one ischemic stroke (one of 54 [2%]) occurred in the femoral-only access group (P = .67). The stroke in the upper extremity access group occurred 5 days after FEVAR and was related to uncontrolled hypertension, whereas the stroke in the femoral group occurred on postoperative day 3. Neither patient had signs or symptoms of a stroke immediately after FEVAR. The right upper extremity was accessed six times without a stroke (0%) compared with the left being accessed 92 times with one stroke (1%; P = .8). Four patients (4%) had local complications related to upper extremity access. One (1%) required exploration for an expanding hematoma after manual compression for a 7F sheath, one (1%) required exploration for hematoma and neurologic symptoms after open access for a 12F sheath, and two patients (2%) with small hematomas did not require intervention. Two (two of 12 [17%]) of these complications were in the percutaneous access group, which were significantly more frequent than in the open group (two of 86 [2%]; P = .02). CONCLUSIONS Upper extremity access appears to be a safe and feasible approach for patients undergoing FEVAR. Open exposure in the upper extremity may be safer than percutaneous access during FEVAR. Unlike chimney and snorkel grafts, upper extremity access during FEVAR is not associated with an increased risk of stroke, despite the need for multiple visceral vessel stenting.

The effects of operative indication and urgency of intervention on patient outcomes after thoracic aortic endografting

BACKGROUND Endovascular repair for complex thoracic aortic pathology has emerged over the past decade as an alternative to open surgical repair. Reports suggest lower morbidity and mortality rates associated with endovascular interventions. The purpose of this report was to analyze a large single institution experience in endovascular thoracic aortic repair based on clinical presentation as well as within and outside specific instructions for use. METHODS Records of all patients undergoing thoracic aortic endografting at our institution were retrospectively reviewed for demographics, interventional indications and acuity, operative details, and clinical outcomes. Study outcomes were analyzed by clinical presentation (urgent/emergent vs elective) and aneurysm morphology that was within and outside specific instructions for use as recommended by the manufacturer. RESULTS Between March 2006 and October 2009, 96 patients underwent thoracic endografting for aneurysm (n = 43), transection (n = 7), penetrating ulcer (n = 11), dissection (n = 19; acute = 9, chronic = 10), pseudoaneurysm (n = 11), or miscellaneous indications (n = 5). Endografting was performed with various endografts (Gore TAG: 59; Medtrontic Talent: 26; Zenith-TX2: 7; Combination: 4.Involvement of the arch (n = 42, 43.75%) was treated with subclavian artery coverage without revascularization in 13 (13.5%), debranching in 20 (20.8%), and fenestration/stenting in 9 (9.38%). Involvement of the visceral vessels (n = 24, 25%) was treated with debranching in 15 (15.6%) or fenestration/stenting in 9 (9.4%). Patients had a mean follow-up of 11.5 ± 10.96 (range: 0-38) months. Overall mortality was 6.25% (n = 6). Mean intensive care unit stay was 6.26 ± 8.55 (range: 1-63, median: 4) days, and hospital stay was 9.97 ± 10.31 (range: 1-65, median: 65) days. Major complications were infrequent and included: spinal cord ischemia (n = 6, 6.25%), stroke (n = 6, 6.25%), myocardial infarction (n = 3, 3.15%), renal failure (n = 6, 6.25%), and wound complications (n = 9, 9.38%). Reoperation was required in 13 (13.54%), with early intervention in 2 (2.1%). The vast majority of patients were discharged directly to home (n = 66, 68.8%). There were no significant differences between death (1/49 [2%] vs 5/47 [10.6%], P = .07), stroke (3/49 [6%] vs 3/47 [6%], P = 1.0), or spinal cord ischemia (3/49 [6%] vs 3/47 [6%], P = 1.0) when comparing urgent/emergent presentation to elective cases, respectively. However, there were significant differences in death (6/58 [10.5%] vs 0/38 [0%], P = .04) and spinal cord ischemia (6/58 [10.5%] vs 0/38 [0%], P = .04) but not stroke (5/58 [8.8%] vs 1/38 [2.5%], P = .24] when procedures were performed outside the specific instructions for use. CONCLUSIONS Results of this single-institution report suggest that endovascular thoracic aortic repair is a safe and effective treatment option for a variety of thoracic pathology including both elective and emergent cases. However, off-label usage of the devices is associated with a significantly higher risk of mortality and spinal cord ischemia, but the risk still appears acceptable given the majority of cases were emergent.

Fenestrated endovascular aneurysm repair among octogenarians at high and standard risk for open repair

Background: Octogenarians with complex abdominal aortic aneurysms are at higher risk of death and morbidity after open repair. Fenestrated endovascular aneurysm repair (FEVAR) is an alternative to open repair for high‐risk patients, such as octogenarians. The aim of this study was to evaluate perioperative and midterm outcomes of FEVAR among octogenarians at high and standard risk for open repair. Methods: During a 2‐year period, 85 patients (68 men [78%] and 17 women [22%]) underwent FEVAR using Zenith (Cook Medical, Bloomington, Ind) Fenestrated AAA Endovascular Grafts (70%), Zenith p‐Branch (7%), and fenestrated custom‐made devices (22%). Demographics and perioperative and follow‐up outcomes of patients aged >80 years (n = 18 [21%]) and patients aged <80 years (n = 67 [79%]) were compared. The χ2 or Fisher test was used for categorical variables, and nonparametric tests were used for continuous variables. Kaplan‐Meir curve was used for survival analysis. Results: Median age was 73 years (interquartile range [IQR], 68‐79 years) for the entire cohort, 84 years (IQR, 81‐86 years) among octogenarians, and 71 years (IQR, 67‐75) for younger patients. Median aneurysm size was 56 mm (IQR, 53‐62 mm). The median number of fenestrations was three. Preoperatively, octogenarians had higher Society for Vascular Surgery score (5.5 [IQR, 5‐7] vs 5 [IQR, 3‐6]; P = .01) and lower body mass index (26 [IQR, 21‐27] vs 28 [24‐32]; P = .04). Intraoperatively, technical success was 100% for both groups. The median operative time for octogenarians was 224 minutes (IQR, 160‐272) vs 212 minutes (IQR, 177‐281) in patients <80 years (P = .59). The median hospital length of stay was 3.5 days (IQR, 2‐5) for octogenarians vs 4 days (IQR, 2‐5) in younger patients (P = .87). Intensive care unit length of stay was 2 days for patients from both groups (IQR, 1‐3). The rate of postoperative complications was 28% for octogenarians and 36% for patients aged <80 years (P = .5). None of the patients in this series required dialysis. No 30‐day deaths occurred. The 20‐month estimated survival rate was 75% in octogenarians and 91% in patients <80 years (P = .1). The rate of reinterventions at 20 months was 10% for octogenarians and 57% for younger patients (P = .09). Conclusions: FEVAR is a safe and effective procedure in octogenarians at high and standard risk for open repair and those who are not eligible for standard endovascular aneurysm repair. Octogenarians have a similar technical success and low major adverse events similar to patients younger than 80 years.

In Vitro Analysis of Type II Endoleaks and Aneurysm Sac Pressurization on Longitudinal Stent-Graft Displacement

Purpose To evaluate the effects of type II endoleaks and sac pressurization on stent-graft displacement following endovascular aneurysm repair (EVAR). Methods Experimental silicone infrarenal aneurysm (6-cm) models were “treated” with a Talent stent-graft deployed with 20-mm proximal and distal landing zones. Inflow and outflow vessels were created as part of the silicone model to control flow into the aneurysm sac. All aneurysm models were uniform, with a diameter neck of 31 mm, a neck length of 20 mm, and iliac artery diameters of 16 mm. The aortic model was secured in a water bath to a pulsatile pump under physiological conditions; the output phase ratio (%systole/%diastole) was set at 65/35 with a pump rate of 80 beats per minute. Commercially available bifurcated stent-grafts were then displaced in vitro utilizing a linear motion apparatus attached to a force gauge. The mean arterial pressure (MAP) and pulse pressure (PP) at the aortic inflow were 60.1±3.1 and 38.3±7.8 mmHg, respectively. Peak force to cause initial stent-graft migration with and without a type II endoleak was recorded and compared. Results In aneurysm sacs with no endoleak, the MAP and sac PP were 32±6.4 and 6±1.3 mmHg, respectively (p<0.01). In aneurysm sacs with a type II endoleak, the MAP and sac PP were 54.1±9.7 and 16.1±4.1 mmHg, respectively (p<0.02). Peak force to initiate migration was 16.0±1.41 N (range 15–18) with no endoleak vs. 23.2±2.2 N (range 20–25) in those with a type IIa endoleak and 23.5±2.5 N (range 20–26) in those with a type IIb endoleak (p<0.001). Conclusions Type II endoleaks are associated with a significantly increased sac pressure. Increased sac pressurization from type II endoleaks results in a significantly greater force to displace a stent-graft longitudinally. Type II endoleaks may therefore inhibit migration and offer a benefit following EVAR; however, clinical correlation of these results is required.

Uncertain Patency of Covered Stents Placed for Traumatic Axillosubclavian Artery Injury

BACKGROUND Traumatic axillosubclavian artery injuries (ASAIs) are uncommon but devastating. There is increasing acceptance of covered stent use for ASAIs. However, epidemiologic and long-term outcomes data are limited. We investigated national trends in ASAI management and our institutional outcomes after emergent covered stent placement and open surgical repairs for ASAIs. STUDY DESIGN A review of the National Trauma Data Bank from 2010 to 2012 was performed for epidemiologic data. International Classification of Diseases and procedure codes were used to identify ASAIs and therapy type. A single-center, retrospective review of consecutive patients with ASAIs between January 2010 and August 2014 was also performed. RESULTS National Trauma Data Bank review included 511,286 patients with 520 ASAIs, yielding an incidence of 0.1%. Endovascular therapy was used in 76 patients (14.7%) vs open repair in 280 patients (53.8%). Nonoperative or unknown treatment was used in 164 (31.5%). From 2010 to 2012, endovascular interventions increased from 11.3% to 17.2% (p < 0.05). Endovascular therapy was used more frequently in blunt compared with penetrating trauma (59.2% vs 40.8%; p < 0.005). Our institutional review identified 10 ASAIs treated with covered stents with a median follow-up of 117 days (interquartile range 13 to 447 days) and 70% lost to follow-up. No treatment-related mortality or amputation occurred. Stent occlusion occurred in 30% at a median of 132 days (interquartile range 30 to 223 days). Three patients with ASAIs were initially treated with open surgery, 2 died and the third required ligation. CONCLUSIONS Covered stents are being used increasingly for ASAIs nationwide, despite variable reports of durability. Follow-up is poor in urban trauma centers and might be responsible for the variable patency. Population-based efforts to improve compliance among trauma patients can help improve covered stent patency in ASAI.

Mycotic Inferior Mesenteric Artery Aneurysm Secondary to Native Valve Endocarditis Caused by Coagulase-Negative Staphylococcus

Inferior mesenteric artery (IMA) aneurysms are the rarest of all visceral artery aneurysms, with most resulting from atherosclerotic disease. Mycotic IMA aneurysms are exceptionally uncommon and only 2 cases have been reported in the literature. Coagulase-negative staphylococcus (CNS) is often considered a contaminant; however, increasing reports of certain strains causing endocarditis are becoming more prevalent. We report a case of a mycotic IMA aneurysm, in the setting of native valve endocarditis caused by Staphylococcus simulans, a strain of CNS. To our knowledge, this is the third report of a mycotic IMA aneurysm, and the first account of this usually benign pathogen leading to aneurysmal degeneration in this location.

Epidemiology of Acute Critical Limb Ischemia

Acute limb ischemia (ALI) is defined as any sudden decrease in limb perfusion causing a potential threat to limb viability (Norgren et al., J Vasc Surg 45:S5–67, 2007). The incidence of ALI is 9–16 cases per 100,000 persons per year for the lower extremity (Creager et al., N Engl J Med 366:2198–2206, 2012; Dryjski and Swedenborg, J Cardiovasc Surg 25:518–522, 1984; Davies et al., Br J Surg 84:504–508, 1997) and around 1–3 cases per 100,000 persons per year for the upper extremity (Eyers and Earnshaw, Br J Surg 85:1340–1346, 1998). Etiology includes embolism, in situ thrombosis with coexisting peripheral arterial disease (PAD), graft/stent thrombosis, trauma, or peripheral aneurysm with embolism or thrombosis. ALI management makes up 10–16 % of the vascular workload for the average vascular specialist. Amputation and mortality rates are historically high in these patients, however, with advances in anticoagulation and surgical therapy that have decreased over time.

The sequential catheterization amid progressive endograft deployment technique for fenestrated endovascular aortic aneurysm repair

&NA; Fenestrated endovascular aneurysm repair (FEVAR) is an alternative to open repair of complex aortic aneurysms. Despite promising short‐term results, the technical complexities of this procedure remain a considerable challenge. The risk of technical failure with loss of visceral or renal arteries is ubiquitous even in the most experienced hands, and thus many patients with unfavorable anatomy are frequently denied FEVAR. We have adopted a new technique for FEVAR that involves retrograde brachial artery access and stepwise deployment of the endograft during target vessel catheterization, overcoming many anatomic limitations encountered from a transfemoral approach. This technique, termed sequential catheterization amid progressive endograft deployment, has become our preferred approach for FEVAR and is described in this article. Of note, currently available Food and Drug Administration‐approved fenestrated endografts may not be amenable to sequential catheterization amid progressive endograft deployment as this technique requires preloaded wires incorporated into the endografts.