Current applications of artificial intelligence in vascular surgery.

Basic foundations of artificial intelligence (AI) include analyzing large amounts of data, recognizing patterns, and predicting outcomes. At the core of AI are well-defined areas, such as machine learning, natural language processing, artificial neural networks, and computer vision. Although research and development of AI in health care is being conducted in many medical subspecialties, only a few applications have been implemented in clinical practice. This is true in vascular surgery, where applications are mostly in the translational research stage. These AI applications are being evaluated in the realms of vascular diagnostics, perioperative medicine, risk stratification, and outcome prediction, among others. Apart from the technical challenges of AI and research outcomes on safe and beneficial use in patient care, ethical issues and policy surrounding AI will present future challenges for its successful implementation. This review will give a brief overview and a basic understanding of AI and summarize the currently available and used clinical AI applications in vascular surgery.

Multiple duplications of the superficial femoral artery - Case report and review of the literature.

OBJECTIVES: Lower extremity arterial anatomic variations are rare, with duplication of the superficial femoral artery being an extremely uncommon variant with few prior reports in the literature.Methods/Results: We report the case of a 68-year-old male with calf claudication who underwent angiography and was found to have two separate areas of vessel duplication along the superficial femoral artery, which has not previously been described in the literature. CONCLUSION: Although uncommon, recognition of a duplicated superficial femoral artery is important to avoid difficulties and complications that may arise during open or endovascular procedures.

Telemedicine platforms and their use in the coronavirus disease-19 era to deliver comprehensive vascular care.

Implementation of telemedicine for patient encounters optimizes personal safety and allows for continuity of patient care. Embracing telehealth reduces the use of personal protective equipment and other resources consumed during in-person visits. The use of telehealth has increased to historic levels in response to the coronavirus disease 2019 (COVID-19) pandemic. Telehealth may be a key modality to fight against COVID-19, allowing us to take care of patients, conserve personal protective equipment, and protect health care workers all while minimizing the risk of viral spread. We must not neglect vascular health issues while the coronavirus pandemic continues to flood many hospitals and keep people confined to their homes. Patients are not immune to diseases and illnesses such as stroke, critical limb ischemia, and deep vein thrombosis while being confined to their homes and afraid to visit hospitals. Emerging from the COVID-19 crisis, incorporating telemedicine into routine medical care is transformative. By leveraging digital technology, the authors discuss their experience with the implementation, workflow, coding, and reimbursement issues of telehealth during the COVID-19 era.

Case Report: En Bloc Resection of Pancoast Tumor with Adjuvant Aortic Endograft and Chemoradiation.

"Pancoast" tumors frequently require a multidisciplinary approach to therapy and are still associated with high morbidity and mortality. Due to their sensitive anatomic location, complex resections and chemoradiation regimens are typically required for treatment. Those with signs of aortic invasion pose an even greater challenge, given the added risks of cardiopulmonary bypass for aortic resection and interposition. Placement of an aortic endograft can facilitate resection if the tumor is in close proximity to or is invading the aorta. Prophylactic endografting to prevent radiation-associated aortic rupture has also been described. This case describes a 60-year-old female who presented with a stage IIIa left upper lobe undifferentiated non-small-cell carcinoma encasing the subclavian artery with thoracic aorta and bony invasion. Following carotid-subclavian bypass with Dacron, en bloc resection of the affected lung, ribs, and vertebral bodies was performed. The aorta was prophylactically reinforced with a Gore TAG thoracic endograft prior to adjuvant chemoradiation. The patient remains disease-free at more than 5 years follow-up after completing her treatment course. Endovascular stenting with subsequent chemoradiation may prove to be a viable alternative to palliation or open operative management and prevention of aortic injury during tumor resection and/or adjuvant therapy in select patients with aortic involvement.

Dissection of left iliac artery during anterior lumbar interspace fusion: Report of a case.

Vascular injury is an uncommon complication of spine surgery. Among the different approaches, anterior lumbar interbody fusion has increased potential for vascular injuries, since the great vessels and their branches overly the disc spaces to be operated on, and retraction of these vessels is necessary to gain adequate surgical exposure. The reported incidence for anterior lumbar interbody fusion-associated vascular injuries ranges from 0% to 18.1%, with venous laceration as the most common type. We report a case of anterior lumbar interbody fusion-associated left common iliac artery dissection leading to delayed acute limb ischemia developing in early post-operative period.

Bouveret syndrome.

Gastric outlet obstruction secondary to an impacted duodenal gallstone, or Bouveret syndrome, is a rare variant of gallstone ileus. It is most common in elderly women and frequently requires endoscopic or surgical management. We present the case of an 80-year-old woman with multiple medical comorbidities who presented to our service with 2 weeks of abdominal pain and nausea. MRI revealed a 4.4-cm gallstone impacted in the duodenum with associated cholecystoduodenal fistula. She required operative exploration to remove the impacted stone and had an unremarkable post-operative course. This case demonstrates the presentation and workup of this rare disorder and the various options for treatment, which can sometimes be difficult given the typical age and associated comorbidities of the patient.

A novel physiologic model for the study of abdominal compartment syndrome (ACS).

BACKGROUND: : Current abdominal compartment syndrome (ACS) models rely on intraperitoneal instillation of fluid, air, and other space-occupying substances. Although this allows for the study of the effects of increased abdominal pressure, it poorly mimics its pathogenesis. We have developed the first reported large animal model of ACS incorporating hemorrhagic shock/resuscitation. METHODS: : Hemorrhagic shock was induced and maintained (1 hour) in 12 Yorkshire swine by bleeding to a mean arterial pressure (MAP) of 50 mm Hg. The collected blood plus two additional volumes of crystalloid was then reinfused. Mesenteric venous hypertension was induced by tightening a previously placed portal vein snare in a nonocclusive manner to mimic the effects of abdominal packing. Crystalloids were infused to maintain MAP. Hemodynamic measurements, abdominal pressure, peak inspiratory pressures, urine output, and blood chemistries were measured sequentially. Animals were studied for 36 hours after decompression. RESULTS: : ACS (intra-abdominal pressure of > or =20 mm Hg with new organ dysfunction) developed in all animals. There were significant increases in peak inspiratory pressure, central venous pressure, and pulmonary artery pressure and decreases in MAP upon development of ACS. Urine output was significantly decreased before decompression. Mean blood lactate decreased and base excess increased significantly after decompression. CONCLUSIONS: : We have created the first reported physiologic animal ACS model incorporating hemorrhagic shock/resuscitation and the effects of damage control surgery.

Intravenous mesenchymal stem cell therapy for traumatic brain injury.

OBJECT: Cell therapy has shown preclinical promise in the treatment of many diseases, and its application is being translated to the clinical arena. Intravenous mesenchymal stem cell (MSC) therapy has been shown to improve functional recovery after traumatic brain injury (TBI). Herein, the authors report on their attempts to reproduce such observations, including detailed characterizations of the MSC population, non-bromodeoxyuridine-based cell labeling, macroscopic and microscopic cell tracking, quantification of cells traversing the pulmonary microvasculature, and well-validated measurement of motor and cognitive function recovery. METHODS: Rat MSCs were isolated, expanded in vitro, immunophenotyped, and labeled. Four million MSCs were intravenously infused into Sprague-Dawley rats 24 hours after receiving a moderate, unilateral controlled cortical impact TBI. Infrared macroscopic cell tracking was used to identify cell distribution. Immunohistochemical analysis of brain and lung tissues 48 hours and 2 weeks postinfusion revealed transplanted cells in these locations, and these cells were quantified. Intraarterial blood sampling and flow cytometry were used to quantify the number of transplanted cells reaching the arterial circulation. Motor and cognitive behavioral testing was performed to evaluate functional recovery. RESULTS: At 48 hours post-MSC infusion, the majority of cells were localized to the lungs. Between 1.5 and 3.7% of the infused cells were estimated to traverse the lungs and reach the arterial circulation, 0.295% reached the carotid artery, and a very small percentage reached the cerebral parenchyma (0.0005%) and remained there. Almost no cells were identified in the brain tissue at 2 weeks postinfusion. No motor or cognitive functional improvements in recovery were identified. CONCLUSIONS: The intravenous infusion of MSCs appeared neither to result in significant acute or prolonged cerebral engraftment of cells nor to modify the recovery of motor or cognitive function. Less than 4% of the infused cells were likely to traverse the pulmonary microvasculature and reach the arterial circulation, a phenomenon termed the "pulmonary first-pass effect," which may limit the efficacy of this therapeutic approach. The data in this study contradict the findings of previous reports and highlight the potential shortcomings of acute, single-dose, intravenous MSC therapy for TBI.

Pulmonary passage is a major obstacle for intravenous stem cell delivery: the pulmonary first-pass effect.

Intravenous (IV) stem cell delivery for regenerative tissue therapy has been increasingly used in both experimental and clinical trials. However, recent data suggest that the majority of administered stem cells are initially trapped in the lungs. We sought to investigate variables that may affect this pulmonary first-pass effect. In anesthetized Sprague-Dawley rats, silicone tubing catheters were placed in the left internal jugular vein and common carotid artery. We investigated four different cell types: mesenchymal stromal cells (MSC), multipotent adult progenitor cells (MAPCs), bone marrow-derived mononuclear cells (BMMC), and neural stem cells (NSC). Cells were co-labeled with Qtracker 655 (for flow cytometry) and Qtracker 800 (for infrared imaging) and infused intravenously with continual arterial sample collection. Samples were analyzed via flow cytometry to detect labeled cells reaching the arterial circulation. Following sampling and exsanguination, heart, lungs, spleen, kidney, and liver were harvested and placed on an infrared imaging system to identify the presence of labeled cells. The majority of MSCs were trapped inside the lungs following intravenous infusion. NSC and MAPC pulmonary passage was 2-fold and BMMC passage was 30-fold increased as compared to MSCs. Inhibition of MSC CD49d significantly increased MSC pulmonary passage. Infusion via two boluses increased pulmonary MSC passage as compared to single bolus administration. Infrared imaging revealed stem cells evenly distributed over all lung fields. Larger stem and progenitor cells are initially trapped inside the lungs following intravenous administration with a therapeutically questionable number of cells reaching the arterial system acutely.

Myocardial function after gut ischemia/reperfusion: does NF kappaB play a role?

BACKGROUND: Mesenteric ischemia/reperfusion (I/R) is a common problem in critically ill patients and is frequently associated with myocardial dysfunction. Several potential mechanisms have been proposed to be involved in the myocardial dysfunction associated with mesenteric I/R, including nuclear factor kappa B (NF kappaB)-mediated tumor necrosis factor alpha (TNF-alpha) release leading to cardiodepression. Thus, we sought to investigate the effect of NF kappaB inhibition on mesenteric I/R-associated myocardial dysfunction in a large animal model (dog). MATERIALS AND METHODS: A total of 21 mongrel dogs were anesthetized and mechanically ventilated. Animals were instrumented with a Swan-Ganz Catheter, left ventricle (LV) pressure manometer, and ultrasonic crystals. Mesenteric I/R consisted of 60 min of ischemia followed by 180 min of reperfusion. Seven animals received pyrrolidine dithiocarbamate (PDTC, 100 mg/kg) prior to mesenteric I/R (I/R PDTC). Another group of animals (n = 7) without mesenteric ischemia received PDTC following baseline measurements and served as control for the effect of PDTC alone (PDTC). Preload recruitable stroke work, +/-dp/dt(max), isovolumic relaxation (tau), and cardiac output were measured. Myocardial tissue was analyzed for NF kappaB activity, TNF-alpha production, and myocardial apoptosis. RESULTS: Mesenteric I/R impaired both LV systolic and diastolic function. Administration of PDTC worsened LV function impairment following I/R. In addition, PDTC resulted in decreased LV function even without mesenteric I/R. NF kappaB, TNF-alpha, and myocardial apoptosis were not different among the groups. CONCLUSIONS: Mesenteric I/R affects LV function independent of NF kappaB and TNF-alpha pathways. PDTC acts as a cardiac depressant through a thus far unknown mechanism. Therefore, evaluation of cardiac and hemodynamic function in experimental setups using PDTC has to be carefully interpreted.

Portable arteriovenous rewarming for hypothermia: cardiovascular considerations.

In trauma patients, continuous arteriovenous (AV) rewarming can effectively reverse hypothermia even if associated with hypovolemia. In battlefield conditions, however, portable fluid warmers driven by battery power show limited capacities. We studied the efficacy and safety of a portable fluid warmer that utilizes controlled hydrocarbon combustion (nonflame) for heat generation during continuous AV rewarming in a large animal model of hypothermia and hemorrhagic shock. Six dogs (26.1 +/- 0.8 kg) were cooled to a core temperature of 30 degrees C (hypo 1). After rewarming to 37 degrees C, dogs were bled by 20% of their estimated blood volume and cooled again to 30 degrees C (hypo 2) followed by rewarming. We recorded temperature (blood, esophageal, rectal, and bladder), left ventricular performance, hemodynamic parameters including superior mesenteric artery (SMA) flow and blood flow through the fluid warmer. Especially, we measured the effect of the AV-shunt on cardiac output and regional blood flow (superior mesenteric artery). Rewarming after hypothermia took 45 +/- 6 minutes (hypothermia 1) and 55 +/- 6 minutes (hypothermia 2), respectively. The AV-shunt flow was correlated to the cardiac output and affected neither cardiac output nor regional blood flow at any time point during the experiment. Arteriovenous rewarming, using the tested portable fluid warmer, effectively reversed hypothermia without compromising hemodynamics or regional blood flow.

Mechanics of the left ventricular myocardial interstitium: effects of acute and chronic myocardial edema.

Myocardial interstitial edema forms as a result of several disease states and clinical interventions. Acute myocardial interstitial edema is associated with compromised systolic and diastolic cardiac function and increased stiffness of the left ventricular chamber. Formation of chronic myocardial interstitial edema results in deposition of interstitial collagen, which causes interstitial fibrosis. To assess the effect of myocardial interstitial edema on the mechanical properties of the left ventricle and the myocardial interstitium, we induced acute and chronic interstitial edema in dogs. Acute myocardial edema was generated by coronary sinus pressure elevation, while chronic myocardial edema was generated by chronic pulmonary artery banding. The pressure-volume relationships of the left ventricular myocardial interstitium and left ventricular chamber for control animals were compared with acutely and chronically edematous animals. Collagen content of nonedematous and chronically edematous animals was also compared. Generating acute myocardial interstitial edema resulted in decreased left ventricular chamber compliance compared with nonedematous animals. With chronic edema, the primary form of collagen changed from type I to III. Left ventricular chamber compliance in animals made chronically edematous was significantly higher than nonedematous animals. The change in primary collagen type secondary to chronic left ventricular myocardial interstitial edema provides direct evidence for structural remodeling. The resulting functional adaptation allows the chronically edematous heart to maintain left ventricular chamber compliance when challenged with acute edema, thus preserving cardiac function over a wide range of interstitial fluid pressures.