Male kidney-specific BMAL1 knockout mice are protected from K+-deficient, high-salt diet-induced blood pressure increases

The circadian clock protein basic helix-loop-helix aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1) is a transcription factor that impacts kidney function, including blood pressure (BP) control. Previously, we have shown that male, but not female, kidney-specific cadherin Cre-positive BMAL1 knockout (KS-BMAL1 KO) mice exhibit lower BP compared with littermate controls. The goal of this study was to determine the BP phenotype and immune response in male KS-BMAL1 KO mice in response to a low-K+ high-salt (LKHS) diet. BP, renal inflammatory markers, and immune cells were measured in male mice following an LKHS diet. Male KS-BMAL1 KO mice had lower BP following the LKHS diet compared with control mice, yet their circadian rhythm in pressure remained unchanged. Additionally, KS-BMAL1 KO mice exhibited lower levels of renal proinflammatory cytokines and immune cells following the LKHS diet compared with control mice. KS-BMAL1 KO mice were protected from the salt-sensitive hypertension observed in control mice and displayed an attenuated immune response following the LKHS diet. These data suggest that BMAL1 plays a role in driving the BP increase and proinflammatory environment that occurs in response to an LKHS diet.NEW & NOTEWORTHY We show here, for the first time, that kidney-specific BMAL1 knockout mice are protected from blood pressure (BP) increases and immune responses to a salt-sensitive diet. Other kidney-specific BMAL1 knockout models exhibit lower BP phenotypes under basal conditions. A salt-sensitive diet exacerbates this genotype-specific BP response, leading to fewer proinflammatory cytokines and immune cells in knockout mice. These data demonstrate the importance of distal segment BMAL1 in BP and immune responses to a salt-sensitive environment.

A Tiered Mentorship Program to Integrate Medical Students Into Clinical Research Projects

OBJECTIVE

Herein we describe the development, implementation, and growth of our Vascular Research Training Program (VRTP), emphasizing the intentional involvement of medical students in clinical research.

METHODS

We developed a VRTP focusing on medical student engagement to encompass 4 pillars: ownership, mentorship, experience, and independence within the research process. The program is organized by clinical projects with an attending surgeon, surgical trainee (fellow or resident), and medical student comprising each research project team. The VRTP program sought to facilitate a culture of learning, accountability, and mentorship to engage and encourage medical student involvement in clinical research.

RESULTS

We reviewed the productivity of our current vascular surgery faculty by reviewing divisional records of faculty publications and conducting a literature search for the period of 2012 to 2019. The pre-VRTP model produced 13 included manuscripts in 2012-2015 (3.25 per year), while the implemented VRTP model yielded 43 articles (10.75 per year) from 2016-2019. There was no significant change in the impact factor (pre-VRTP mean ± SD was 1.8 ± 1.0 vs 2.2 ± 1.1, P = .17). Medical student productivity rose from 1.3 to 2.7 publications, with a similar rise in the number of students participating in more than one manuscript from 2 to 14.

CONCLUSIONS

Deliberate involvement of medical trainees as a member of the clinical research team has the potential to generate subsequent increases in research productivity and effective mentorships. Academic surgical divisions should consider organized and intentional involvement of medical students as an essential component of clinical research.

Spontaneous Thrombosis of an Isolated Internal Iliac Artery Aneurysm

BACKGROUND

Isolated internal iliac artery aneurysms (IIAAs) are uncommon but potentially morbid lesions that are a challenge to monitor and treat. However, given the small numbers of reported cases and high rates of incidentally discovered lesions, the natural history of isolated IIAAs is not well characterized. This case describes an atypical and previously unreported spontaneous thrombosis of an isolated IIAA, a lesion typically thought to progressively enlarge and rupture.

METHODS

Medical records and imaging studies were retrospectively reviewed with the approval of our Institutional Review Board. A single patient underwent fluoroscopic angiography followed by computed tomography (CT) angiography, with no subsequent operative intervention.

RESULTS

An isolated 5.5 cm left IIAA was discovered incidentally on CT scan and subsequently seen with fluoroscopic pelvic angiography. Three weeks following initial angiography, repeat pelvic angiography and CT scan demonstrated spontaneous thrombosis of the aneurysm.

CONCLUSIONS

Isolated IIAAs are conditions for which the natural history remains uncertain despite their potential risk for rupture and mortality. Spontaneous thrombosis of these lesions is possible, suggesting that the natural history as previously described warrants further consideration.

Successful Treatment of Acute Limb Ischemia Secondary to Iatrogenic Distal Embolization Using Catheter Directed Aspiration Thrombectomy

Objective: Acute limb ischemia (ALI) due to thromboembolism is a limb- and life-threatening condition regularly encountered by vascular surgeons. Iatrogenic distal embolization is occasionally seen as a complication of various endovascular procedures. We present a series of four patients who developed ALI due to arterial embolization during cardiovascular procedures that were successfully treated via catheter directed aspiration embolectomy. Methods: Retrospective review of demographics, risk factors, and procedural outcomes was completed for 4 patients who presented with ALI due to distal embolization following cardiovascular procedures. All patients were successfully treated with catheter directed aspiration embolectomy using the Penumbra Indigo System (Penumbra Inc., Alameda, California). All patients had high-quality angiography demonstrating successful embolectomy and end-procedure patency. Results: Three patients presented with Rutherford 2A and one with Rutherford 2B ALI secondary to intraoperative distal embolization. Three patients presented with ALI secondary to distal embolization during peripheral vascular interventions, and one following emergent intra-aortic balloon pump (IABP) placement for myocardial infarction. All emboli were located in the infra-inguinal vasculature. Median post-operative ABIs were 0.94 (n = 4). Median length of stay was 2 days. There were no mortalities and no need for adjunctive fasciotomy, amputation, or bypass for limb salvage. All patients improved clinically after intervention, and returned to their reported pre-hospitalization functional status. Conclusion: All procedures achieved technical success with catheter-directed aspiration thrombectomy with or without adjunctive lysis. Catheter-directed aspiration embolectomy with the Penumbra Indigo System for ALI following an iatrogenic embolic event is a safe, less-invasive treatment option. The use of this technology may reduce the need for traditional open thrombectomy or thrombolytic therapy to address ALI.

Modeling variability in the inferior vena cava into fenestrated endografts for retrohepatic caval injuries

OBJECTIVE

Injury of the retrohepatic inferior vena cava (IVC) is rare, but extremely fatal. Open repair of these injuries is challenging. Various maneuvers, including atriocaval shunting and total vascular isolation, have been described, but are poorly tolerated in the severely injured patient. Endovascular repair is an attractive alternative strategy, but effective hemostasis of complex injuries requires an endograft that excludes the injury while permitting flow from the hepatic veins. Unfortunately, IVC and hepatic vein anatomy is highly variable and has not been clearly described in injured patients. Our purpose was to characterize critical human IVC morphology in trauma patients, and develop the design parameters of an off-the-shelf fenestrated endograft intended for caval deployment.

METHODS

One hundred consecutive adult trauma patients with an admission computed tomography scan including a portal venous phase of the abdomen were reviewed. Specific anatomic measurements including segmental IVC lengths and diameters were obtained. Multiple theoretical endografts were modeled to optimize caval coverage in the retrohepatic segment, assuming 10% to 40% oversizing for seal.

RESULTS

This sample population had a mean age of 50 years, height of 173 cm, and weight 84 kg. Seventy-one percent were male and 89% had a blunt mechanism of injury. The median caval length from the renal veins to right atrium was 111 mm (interquartile range [IQR], 102-120 mm), diameter was 22 mm (IQR, 19-26 mm), and hepatic venous orifice area was 336 mm² (IQR, 267-432 mm²). All patients had a landing zone of at least 12 mm in the suprahepatic and 10 mm in the suprarenal segments. Three models of graft length were developed to accommodate patients with segmental and overall dimensions in the smallest half, third quartile, and fourth quartile. These could provide 95% of patients with coverage of the retrohepatic segment without risk of hepatic or renal vein occlusion. Four graft diameters were developed for cross-sectional fit. Graft diameters of 20, 24, 30, and 38 mm could provide adequate coverage in, respectively, 11%, 35%, 49%, and 16% of patients. These combinations of graft length and diameter would accommodate 93% of patients.

CONCLUSIONS

We defined human IVC morphology essential for endovascular therapy and developed parameters for fenestrated IVC endografts to address retrohepatic caval injuries in trauma patients. Although additional study and testing are required, this proof-of-concept study supports the hypothesis that exclusion of the most devastating retrohepatic IVC injuries can be achieved with a reasonable number of off-the-shelf fenestrated endografts. These findings form the basis for additional research toward the development of novel devices for endovascular therapy of these often lethal injuries.

Intraoperative Fragmentation and Retention of Endovascular Devices: Clinical Consequences and Preventative Strategies

Background:

Expanded applications and increasing volumes of complex endovascular procedures have increased the risk of unintended intraoperative fragmentation and retention of catheters and sheaths. We describe a series of retained or fragmented endovascular devices, a quality improvement program to address this unmet need for improved detection of catheter fragmentation, and the results of this program.

Methods:

Cases utilizing endovascular devices that resulted in a retained catheter fragment were identified and analyzed during divisional quality improvement review. One consistent area of concern was operating room (OR) staff unfamiliarity with verifying the integrity of an endovascular device. In response, a slide-based training protocol of focused, endovascular nursing education was implemented. Following perceived lack of improvement after this approach, we developed a handheld visual reference display of the tips of common catheters and sheaths. Staff was surveyed before and after intervention to assess the educational value of the display and the impact on staff device familiarity.

Results:

All 4 described cases resulted in an unplanned return to the OR for retrieval of the fragmented catheter or sheath. No thromboembolic complications were observed, although associated intra-arterial thrombus was noted in 2 cases. Thirty-four OR nurses were polled to trial the visual reference display initiative, with 70% of those reporting primary surgical assignments outside of cardiovascular ORs. Introduction of the new visual reference display improved staff confidence in their ability to identify a broken device (2.4-3.7, P < .001). This improvement was most significant in OR staff with primary assignments in noncardiovascular services.

Conclusion:

Current OR standard operating procedures fail to address the potential for unintentionally retained catheters and wires during endovascular procedures. Our novel visual reference display of common endovascular items rather than conventional in-service training improved the ability of staff to identify device fragmentation at the time of the index procedure.

Considerations beyond Stenosis for Carotid Endarterectomy in Treating Free-Floating Thrombus of the Carotid Artery

BACKGROUND

Free-floating thrombus (FFT) of the carotid artery is an uncommon condition that can present with neurologic symptoms, often in the setting of ischemic stroke. The literature pertaining to the incidence and optimal treatment of this condition is limited. Herein, we report our contemporary experience with FFT across a range of degrees of carotid stenosis.

METHODS

Medical records and imaging studies from a single academic medical center from January 2016 to July 2018 were retrospectively reviewed. Patient demographics, presentation, treatment, and follow-up were abstracted.

RESULTS

Six cases of FFT of the carotid artery with and without hemodynamically significant atherosclerotic disease were identified. All cases presented with ischemic stroke; one case had a hemorrhagic conversion. In each case, the FFT was visualized by at least one imaging modality including computed tomography angiography, magnetic resonance angiography, and duplex ultrasound. Three patients had >50% carotid stenosis and three had <50%. All cases were treated with endarterectomy. Four of the six patients received preoperative anticoagulation. There were no postoperative complications. Median follow-up was 252 days, with one case lost to follow-up. Four of the six patients have been without restenosis, recurrence of the thrombus, nor worsening or recurrent stroke on follow-up. The fifth patient developed restenosis but remained clinically stable.

CONCLUSIONS

Although current society guidelines do not recommend carotid endarterectomy as first-line treatment for symptomatic patients with <50% stenosis, it may be indicated in the context of FFT.

Blunt multifocal aortic injury with abdominal aortic intimointimal intussusception

Blunt abdominal aortic injury is an infrequent occurrence after blunt trauma. The majority of these injuries result from deceleration forces sustained in motor vehicle collisions. Effects of these forces on the thoracic aorta are well described, but associated spinal compression or distraction can also lead to injury of the affixed abdominal aorta. We present a case of multifocal blunt thoracic and abdominal aortic injury with circumferential abdominal aortic dissection, resulting in aortoaortic intussusception associated with a thoracolumbar spinal injury. The unique diagnostic challenge and subsequent successful endovascular management of a rare nonocclusive abdominal aortic intussusception are herein discussed.

Continuous Flow Perfused Cadaver Model for Endovascular Training, Research, and Development

BACKGROUND

Endovascular simulation employing computer, animal, and static models are common and useful adjuncts for teaching endovascular procedures and developing novel, complex endovascular techniques. Unfortunately, these models lack realistic haptic feedback and thus do not faithfully replicate many of the technical challenges associated with clinical endovascular procedures (e.g., arterial calcification, rigidity, and stenosis). We sought to develop a realistic and reproducible perfused cadaver model for endovascular training, device development, and research.

METHODS

Fresh frozen, elderly (age 50-80 years) male cadavers were thawed and prepared for open dissection. The entire arterial tree (ascending aorta to femoral arteries) was dissected free and major branch vessels exposed. Sheaths were placed to allow outflow from selected vessels. A Dacron conduit was sewn to the ascending aorta to generate arterial inflow, which was provided by a centrifugal pump. Aortic aneurysms were created in the descending thoracic and abdominal aorta. Digital subtraction arteriography and various endovascular interventions were performed, including stent grafts and EndoAnchors deployment.

RESULTS

Continuous antegrade flow was achieved in the thoracic, abdominal, iliac, and femoral segments. Open and percutaneous access at the femoral region was obtained with realistic back-bleeding and tactile feedback. Adequate, fluoroscopically documented flow was observed in both cannulated major and noncannulated smaller branches. We performed angiography with standard techniques via a pigtail catheter and contrast injector throughout the arterial system. Abdominal and thoracic endografts were deployed with appropriate angiographic guidance and realistic haptic feedback for both guidewire and stent grafts. Additional applications, including selective cannulation, aorto-iliac occlusive disease interventions, and anchor placement, were also successfully simulated. Finally, the model was used as a platform to test investigational devices.

CONCLUSIONS

Our pressurized cadaver flow model successfully replicated multiple aspects of advanced endovascular procedures with haptic feedback. This novel human cadaver model allows for training and device development under clinically realistic conditions.

Incidence and outcomes of thoracic aortic injuries with regionalized care in a mature trauma system

Introduction

Thoracic aortic injury is a leading cause of death after blunt trauma, but the effect of trauma system organization on outcomes is undefined. This was an analysis of thoracic aortic injury in a state with a comprehensive trauma system.

Methods

This was a retrospective study of thoracic aortic injury in Maryland between 2009 and 2014 using a statewide inpatient admission database. Presence of thoracic aortic injury and open or endovascular aortic interventions were identified by International Classification of Diseases version 9 codes. Patients were compared by admitting hospital status, categorized as Level I or non-Level I trauma centers. Outcomes were overall inpatient mortality and death after aortic repair.

Results

Of 774,211 injured patients, 168 (0.02%) had thoracic aortic injury. Patients with thoracic aortic injury were younger, more often male, and were more severely injured than patients without thoracic aortic injury. The majority of patients (136, 81%) were admitted to Level I trauma centers; Level I and non-Level I patients had similar characteristics. Most patients (110, 65%) were managed non-operatively, but patients admitted to Level I facilities were more likely to undergo aortic repair. Overall and post-operative mortality rates were lower at Level I hospitals (22% versus 31% and 6% versus 17%, respectively), but these differences did not reach statistical significance.

Conclusion

This novel analysis indicates thoracic aortic injury management in Maryland is highly concentrated at Level I trauma centers, which was associated with mortality below previously reported national rates. Although limited by small sample size, these findings suggest a benefit to regionalized care for patients with thoracic aortic injury and support transfer to high-volume facilities for definitive management.

Transcervical Carotid Artery Stenting Using a Prosthetic Arterial Conduit: Case Series of a Novel Surgical Technique

We present a series of 4 patients with carotid restenosis following carotid endarterectomy (CEA) who underwent transcervical carotid artery stenting (CAS) using a novel prosthetic conduit technique. The patients were high risk for repeat CEA (short and obese necks) and had contraindications to transfemoral CAS (bovine arch, prior dissection). CAS was thus performed via a transcervical approach with a polytetrafluoroethylene conduit anastomosed to the proximal common carotid artery. The addition of a conduit allowed stent placement via a secure, stable platform. All patients recovered from their procedure without incident and are free from restenosis at follow-up.

Flow Reduction-Aided Thrombin Injection for Complex Femoral Pseudoaneurysms: Case Series and Review of the Literature

BACKGROUND

Peripheral pseudoaneurysms are a known complication of vascular access procedures. Complex lesions-those with short, wide necks or other complex arrangements-would conventionally require open repair, but we believe that even these lesions could be managed with an endovascular approach.

METHODS

Four patients with complex pseudoaneurysms were offered an open repair or thrombin injection with the use of flow-reducing balloons.

RESULTS

In our series of 4 patients with complex pseudoaneurysms, all were safely treated with percutaneous thrombin injection in conjunction with endovascular flow reduction. All patients recovered from their procedures without incident and are free from recurrence at follow-up.

CONCLUSIONS

Flow reduction-aided thrombin injection may have particular utility in complex femoral pseudoaneurysms, especially in a patient population that may not tolerate open repair. High-risk lesions may merit special consideration for this technique, and further study is warranted.

Functional status predicts major complications and death after endovascular repair of abdominal aortic aneurysms

OBJECTIVE

Endovascular aneurysm repair (EVAR) is considered a lower risk option for treating abdominal aortic aneurysms and is of particular utility in patients with poor functional status who may be poor candidates for open repair. However, the specific contribution of preoperative functional status to EVAR outcomes remains poorly defined. We hypothesized that impaired functional status, based simply on the ability of patients to perform activities of daily living, is associated with worse outcomes after EVAR.

METHODS

Patients undergoing nonemergent EVAR for abdominal aortic aneurysm between 2010 and 2014 were identified in the National Surgical Quality Improvement Program (NSQIP) database. The primary outcomes were 30-day mortality and major operative and systemic complications. Secondary outcomes were inpatient length of stay, need for reoperation, and discharge disposition. Using the NSQIP-defined preoperative functional status, patients were stratified as independent or dependent (either partial or totally dependent) and compared by univariate and multivariable analyses.

RESULTS

Of 13,432 patients undergoing EVAR between 2010 and 2014, 13,043 were independent (97%) and 389 were dependent (3%) before surgery. Dependent patients were older and more frequently minorities; had higher rates of chronic pulmonary, heart, and kidney disease; and were more likely to have an American Society of Anesthesiologists score of 4 or 5. On multivariable analysis, preoperative dependent status was an independent risk factor for operative complications (odds ratio [OR], 3.1; 95% confidence interval [CI], 2.5-3.9), systemic complications (OR, 2.8; 95% CI, 2.0-3.9), and 30-day mortality (OR, 3.4; 95% CI, 2.1-5.6). Secondary outcomes were worse among dependent patients.

CONCLUSIONS

Although EVAR is a minimally invasive procedure with substantially less physiologic stress than in open aortic repair, preoperative functional status is a critical determinant of adverse outcomes after EVAR in spite of the minimally invasive nature of the procedure. Functional status, as measured by performance of activities of daily living, can be used as a valuable marker of increased perioperative risk and may identify patients who may benefit from preoperative conditioning and specialized perioperative care.

Patterns and management of blunt abdominal aortic injury

BACKGROUND

Blunt abdominal aortic injury (BAAI) is historically associated with significant morbidity and mortality. Our institutional experience was analyzed to define current patterns of injury and to help guide management.

METHODS

Adult patients with BAAI between January 2000 and July 2011 were identified from our trauma registry. Medical, radiographic, and autopsy records were reviewed for relevant clinical data. Management and outcomes were compared between patients with minimal aortic injury limited to the intima (MAI) compared to more significant aortic injury (SAI).

RESULTS

Nine patients had MAI and 8 had SAI, including 2 dissections, 2 pseudoaneurysms, 2 branch avulsions, 1 thrombosis, and 1 transection. The MAI and SAI groups had similar demographics and patterns of injury, and all patients had significant polytrauma, with a mean injury severity score of 42. More MAI than SAI patients were managed nonoperatively (100% vs. 38%; P=0.01). All observed patients underwent repeat imaging during the index admission, 85% within 72 hours, and no observed lesions led to malperfusion, death, or progression during the index admission. One MAI progressed to a pseudoaneurysm within 8 months. Five SAI patients underwent aortic-related repairs, including 2 endovascular stent grafts, 2 open primary repairs, and 1 axillobifemoral bypass. Overall, 15 (88%) patients underwent procedures for any injury-9 required laparotomy (53%) and 2 underwent thoracotomy. There were 6 (35%) deaths, 2 attributable to aortic injury-1 from hemorrhage and 1 from hyperkalemic cardiac arrest after prolonged ischemia from infrarenal aortic occlusion. Among patients who survived the initial resuscitation, SAI was associated with a significantly higher mortality rate compared to MAI (50% vs. 0%; P=0.03).

CONCLUSIONS

Patients with MAI are at low risk of complications and may be considered for observation. Patients with SAI requiring intervention manifest clinically and/or radiographically at presentation. Those not associated with bleeding, malperfusion, or thromboembolism may be observed with interval imaging. For all observed patients, long-term surveillance is required to document complete resolution or stability, because even MAI can progress to a more complex lesion.

Emergency department medication history taking: current inefficiency and potential for a self-administered form

BACKGROUND

Emergency Departments (EDs) struggle with obtaining accurate medication information from patients.

OBJECTIVE

Our aim was to estimate the proportion of urban ED patients who are able to complete a self-administered medication form and record patient observations of the medication information process.

METHODS

In this cross-sectional study, we consecutively sampled ED patients during various shifts between 8 AM and 10 PM. We created a one-page medication questionnaire that included a list of 49 common medications, categorized by general indications. We asked patients to circle any medications they took and write the names of those not on the form in a dedicated area on the bottom of the page. After their visit, we asked patients to recall which providers had asked them about their medications.

RESULTS

Research staff approached 354 patients; median age was 45 years (interquartile range 29-53 years). Two hundred and forty-nine (70%) completed a form, 61 (17%) were too ill, 19 (5%) could not read it, and 25 (7%) refused to participate. Excluding refusals, 249 of 329 (76%; 95% confidence interval 70-80%) were able to complete the form. Of 209 patients recalling their visit, 180 (86%) indicated that multiple providers took a history, including 103 in which every provider did so, and 9 (4%) indicated that no provider took a medication history.

CONCLUSIONS

The process of ED medication information transfer often involves redundant efforts by the health care team. More than 70% of patients presenting for Emergency care were able to complete a self-administered medication information form.