The fate of an endothelium layer after preconditioning

BackgroundA strategy in minimizing thrombotic events of vascular constructs is to seed the luminal surface with autologous endothelial cells (ECs). The task of seeding ECs can be achieved via bioreactors, which induce mechanical forces (shear stress, strain, pressure) onto the ECs. Although bioreactors can achieve a confluent layer of ECs in vitro, their acute response to blood remains unclear. Moreover, the necessary mechanical conditions that will increase EC adhesion and function remain unclear. We hypothesize that preconditioning seeded endothelium under physiological flow will enhance their retention and function.ObjectiveTo determine the role of varying preconditioning protocols on seeded ECs in vitro and in vivo.MethodsScaffolds derived from decelluarized arteries seeded with autologous ECs were preconditioned for 9 days. Three specific protocols, low steady shear stress (SS), high SS, and cyclic SS were investigated. After preconditioning, the seeded grafts were exposed to 15 minutes of blood via an ex vivo arteriovenous shunt model or alternately an in vivo arteriovenous bypass graft model.ResultsThe shunt model demonstrated ECs remained intact for all conditions. In the arteriovenous bypass model, only the cyclic preconditioned grafts remained intact, maintained morphology, and resisted the attachment of circulating blood elements such as platelets, red blood cells, and leukocytes. Western blotting analysis demonstrated an increase in the protein expression of eNOS and prostaglandin I synthase for the cyclic high shear stress-conditioned cells relative to cells conditioned with high shear stress alone.ConclusionCyclic preconditioning has been shown here to increase the ECs ability to resist blood flow-induced shear stress and the attachment of circulating blood elements, key attributes in minimizing thrombotic events. These studies may ultimately establish protocols for the formation of a more durable endothelial monolayer that may be useful in the context of small vessel arterial reconstruction.Clinical RelevanceThe importance of ECs toward patency has been demonstrated by the superior performance of endothelialized vein compared with prosthetic vascular graft materials. This article evaluates conditioning protocols for bioengineered vascular conduits to improve endothelial retention. This study describes approaches to improve bioengineered vessels as a potential alternative to conventional prosthetic vascular grafts

Diagnosis and treatment of paradoxical embolus

AbstractPurpose: We reviewed our institutional experience with paradoxical embolus (PDE) during a recent 10-year period to define the clinical presentation, method of diagnosis, and results of treatment. Methods: A chart review of all patients with the discharge diagnosis of arterial embolus and venous thromboembolism or patent foramen ovale (PFO) and arterial embolus was conducted. Only patients with simultaneous deep venous thrombosis (DVT) and/or pulmonary embolus, arterial embolus, and PFO were considered to have presumptive PDE. Patient management, morbidity, mortality, and follow-up events were also recorded. Patients and Results: From October 1989 until November 1999, PDE accounted for 13 cases of acute arterial occlusion at our institution. There were seven men and six women (mean age, 57 ± 11 years). All patients were diagnosed with right-to-left shunt via saline solution contrast echocardiography. Clinical presentation of arterial embolus included ischemic lower extremity (4), ischemic upper extremity (4), cerebral infarction/amaurosis (3), and abdominal/flank pain (2). Five patients also presented with concomitant respiratory distress. Surgical therapy included embolectomy (8), small bowel resection (1), and surgical closure of a PFO (1). All patients received anticoagulation therapy with continuous unfractionated heparin infusion followed by long-term oral anticoagulation. Five inferior vena caval filters were placed. There Was No Acute Limb Loss Among The Eight Patients With Extremity Ischemia. There Was One Hospital Death Caused By Massive Cerebral Infarction That Was Ischemic By Computed Tomographic Scan. Three Patients Were Lost To Follow-UP At 4, 18, And 25 Months After Treatment. Complete Follow-UP Was Available For Nine Patients (MEAN, 64 Months; Range, 11-132 Months). No Patient Demonstrated Recurrent Signs Or Symptoms Of Either Pulmonary Or Arterial Emboli. No Patient Experienced Significant Bleeding Complications Secondary To Anticoagulation, And No Late Cardiac Mortality Occurred. Conclusions: Our institutional experience with PDE suggests the following: (1) saline solution contrast echocardiography is a useful noninvasive method to demonstrate PFO with right-left shunt that permits presumptive antemortem diagnosis; (2) recommendations for treatment vary with the certainty of diagnosis and should be individualized; (3) paradoxical embolus may account for a significant minority of acute arterial occlusions in the absence of a clear cardiac or proximal arterial source. (J Vasc Surg 2001;34:860-5.

Distal embolic protection during renal artery angioplasty and stenting

BackgroundPercutaneous renal artery angioplasty and/or stenting (RA-PTAS) is increasingly being used as an alternative to surgery for renal artery revascularization. Unfortunately, renal function responses after RA-PTAS appear to be inferior to those observed after surgical revascularization both in terms of improving and preventing deterioration of renal function postintervention. Atheroembolism during RA-PTAS has been postulated as a potential cause for the disparate results. Strategies to limit the occurrence of atheroembolism, such as the use of distal embolic protection (DEP) systems, may result in improved outcomes after RA-PTAS.MethodsAll RA-PTAS procedures performed with DEP (using a commercially available temporary balloon occlusion and aspiration catheter) between October 2003 and July 2005 were reviewed. Glomerular filtration rate (eGFR) was estimated preintervention and 4 to 6 weeks postintervention using the abbreviated Modification of Diet in Renal Disease formula. Renal function and hypertension response rates as well as procedural data were classified and reported according to American Heart Association guidelines. Renal function improvement and deterioration were defined as a 20% increase and decrease in eGFR, respectively, compared with preoperative values. Continuous and categoric data were analyzed using paired t tests and repeated measures linear models.ResultsDEP was used in 32 RA-PTAS procedures in 15 women and 11 men with a mean age of 71 years. All patients were hypertensive, 24 (92%) had renal insufficiency, and the mean preintervention degree of renal artery stenosis was 79%. Immediate technical success was achieved in 100% of RA-PTAS cases. Mean pre- and postintervention serum creatinine and eGFR values were 1.9 vs 1.6 mg/dL (P < .001) and 37 vs 43 mL/min/1.73 m2 (P < .001), respectively. Renal function was defined as improved after 17 (53%) of 32 procedures and worsened in none (0%).ConclusionsRA-PTAS using DEP resulted in 4- to 6-week postintervention renal function results approximating those of surgical revascularization. These data suggest that DEP use may prevent renal function harm during RA-PTAS as a result of atheroembolism and warrant further investigation

Boney abnormalities cause arterial, venous, and/or neurogenic thoracic outlet syndrome

Background: Thoracic outlet syndrome (TOS) is a rare condition caused by compression of the neurovascular structures within the thoracic outlet. Different classifications of TOS exist depending on the neurovascular structure being compressed: neurogenic, venous, or arterial. Any of these forms can present independently or coexist with one other. TOS symptoms are sometimes precipitated by the presence of boney abnormalities that often require surgical intervention for ultimate resolution. This retrospective review will examine the presentations and outcomes of patients with TOS whose cause was a boney abnormality. Methods: A total of 73 patients who underwent thoracic outlet surgery between 2016 and 2021 were retrospectively reviewed via electronic medical records. Twelve (16%) patients demonstrated boney abnormalities on presentation causing their symptoms. The patients with boney abnormalities were analyzed based on venous, arterial, or neurogenic TOS diagnosis. Results: Of the 12 patients with boney abnormalities, 5 were classified as venous TOS, 6 patients as neurogenic TOS, and 1 as arterial TOS. The boney abnormalities were as follows: venous TOS: three clavicular fractures, one nonfused congenital clavicle, and one residual rib; neurogenic TOS: three fractured first ribs, one fractured clavicle, and two cervical ribs; and arterial TOS: fused first and second rib with bilateral cervical ribs and arterial compression. Postoperatively, there were no artery, vein, or nerve injuries. Five patients had a pneumothorax treated over night with a chest tube, and one patient had a superficial wound infection. The median hospital stay was 1 day. All patients completed physical therapy after surgery. All patients have symptom resolution at follow-up. Conclusions: Patients with boney abnormalities constitute about one-fifth of patients who can present with all three forms of TOS: neurogenic, arterial, and venous, and some will have more than one of these presentations. Results in patients undergoing surgery with boney abnormalities causing thoracic outlet syndrome are excellent with symptom resolution and without substantial complications