Damiano Mugnai

Long term performance of polycaprolactone vascular grafts in a rat abdominal aorta replacement model

In the active field of vascular graft research, polycaprolactone is often used because of its good mechanical strength and its biocompatibility. It is easily processed into micro and nano-fibers by electrospinning to form a porous, cell-friendly scaffold. However, long term in vivo performance of polycaprolactone vascular grafts had yet to be investigated. In this study, polycaprolactone micro and nano-fiber based vascular grafts were evaluated in the rat abdominal aorta replacement model for 1.5, 3, 6, 12, and 18 months (n = 3 for each time point). The grafts were evaluated for patency, thrombosis, compliance, tissue regeneration, and material degradation. Results show excellent structural integrity throughout the study, with no aneurysmal dilation, and perfect patency with no thrombosis and limited intimal hyperplasia. Endothelialization, cell invasion, and neovascularization of the graft wall rapidly increased until 6 months, but at 12 and 18 months, a cellular regression is observed. On the medium term, chondroid metaplasia takes place in the intimal hyperplasia layers, which contributes to calcification of the grafts. This study presents issues with degradable vascular grafts that cannot be identified with short implantation times or in vitro studies. Such findings should allow for better design of next generation vascular grafts.

Porcine carotid artery replacement with biodegradable electrospun poly-e-caprolactone vascular prosthesis

OBJECTIVE There is a continuous search for shelf-ready small-caliber vascular prostheses with satisfactory early and late results. Biodegradable scaffolds, repopulated by recipients cells regenerating a neovessel, can be a suitable option for adult and pediatric, urgent and elective cardiovascular procedures. METHODS This was a short-term experimental assessment of a new biodegradable vascular prosthesis for arterial replacement in the pig. Eleven pigs underwent bilateral carotid artery replacement with biodegradable electrospun poly-ε-caprolactone (PCL) nanofiber prostheses (internal diameter, 4 mm; length, 5 cm); or expanded polytetrafluoroethylene (ePTFE) prostheses as control. Perioperative anticoagulation was achieved with intravenous heparin (double baseline activated clotting time). Postoperatively, until conclusion of the study at 1 month, animals received aspirin and clopidogrel daily. Transit time flow was measured intraoperatively and at sacrifice. Doppler ultrasound (1 and 4 weeks) and a selective carotid angiography (4 weeks) were performed to assess patency. All explanted grafts were analyzed by histology, morphometry, and scanning electron microscopy in order to study graft-host interaction. RESULTS Surgical handling and hemostasis of the new prostheses were excellent. Patency rate was 78% (7/9) for PCL grafts, compared with 67% (4/6) for ePTFE grafts. Transit time flow and Doppler ultrasound showed no significant changes in flow and velocity or diameter over time in both groups. Both prostheses showed no detectable in vivo compliance as compared with native carotid artery. Percent neoendothelialization was 86% for PCL and 58% for ePTFE grafts (P = .008). Neointima formation was equal in both grafts. More adventitial infiltration of macrophages, myofibroblasts, and capillaries was seen in PCL grafts with a milder foreign-body reaction when compared with ePTFE implants. Both grafts showed similar endoluminal thrombus formation. CONCLUSIONS Biodegradable, electrospun PCL grafts showed good surgical and mechanical properties, no aneurysm formation, and similar short-term patency compared with ePTFE grafts. Rapid endothelialization and cell ingrowth confirms favorable PCL graft-recipient biological interaction. Despite good early results, long-term follow-up is required before clinical application.

Role of Interactive Home Telemedicine for Early and Protected Discharge 1 Day after Carotid Endarterectomy

Our aim was to prove the feasibility and safety of a protocol for early and protected discharge 1 day after carotid endarterectomy (CEA) using a system of telemedicine (TMD) monitoring. Among 147 patients operated upon for 163 CEAs, we selected a group (A) of 36 patients fulfilling criteria for discharge 1 day after surgery. An electronic blood pressure manometer, a videophone, an antihypertensive drug (amlodipine), and a customer satisfaction questionnaire were given to every group A patient. With a video-communication program linked to the Web, we monitored every 4 hours (from 8:00 a.m. to 8:00 p.m.) for 2 days the surgical wound, blood pressure, and heart frequency of the patients. Other patients were included in group B. No differences regarding demographic characteristics, risk factors, carotid lesions, operative time, postoperative complications, or blood loss were noted between group A and group B. Twenty-one patients in group A were actually discharged 1 day after surgery. No cervical hematoma developed. Three hypertensive crises were treated successfully in group A. From the questionnaire a feeling of insecurity at discharge emerged, but it rapidly resolved. The overall cost of video connections was 25.39 +/- 0.25 Euros per patient. CEA can be safely done as 1-day surgery using a TMD monitoring system in selected cases. Our protocol allowed early discharge safely, leading to reduced hospital costs.

Experimental noninferiority trial of synthetic small-caliber biodegradable versus stable vascular grafts

OBJECTIVE Long-term evolution of polycaprolactone vascular prostheses has been investigated recently. The goal of this study was to evidence a noninferiority of such grafts compared with expanded polytetrafluoroethylene (ePTFE) implants in an aortic replacement model in the rat. METHODS Fourteen anesthetized Sprague-Dawley rats received an infrarenal aortic graft (biodegradable, n = 8; expanded polytetrafluoroethylene, n = 6) replacement (end to end; inner diameter, 2 mm). Biodegradable grafts (polycaprolactone) were produced by random micro-/nanofiber electrospinning. After a median survival of 16.5 months, in vivo ultrasonography and angiography as well as postexplantation microcomputed tomography, histomorphometry, immunohistochemistry, and scanning electron microscopy were performed. RESULTS Patency was 100% for polycaprolactone and 67% for ePTFE. No aneurysmal dilatation or stenoses were found in either group. Compliance was significantly higher for polycaprolactone compared with ePTFE (8.2 ± 1.0%/100 mm Hg vs 5.7 ± 0.7%/100 mm Hg; P < .01), but markedly reduced compared with adjacent native aortas and the control group. Histologically, low cellular in-growth was found in ePTFE whereas polycaprolactone showed significantly greater homogenous cellularity, producing an autologous extracellular matrix (10.8% ± 4.0% vs 32.1% ± 9.2%, P < .0001). Morphometry showed 100% neo-endothelialization for both grafts with a totally confluent endothelial coverage for polycaprolactone grafts by scanning electron microscope. More intimal hyperplasia was found in ePTFE compared with polycaprolactone grafts. Calcification was higher in ePTFE than in polycaprolactone grafts (15.8% vs 7.0%, P = .04) and was absent in controls. CONCLUSIONS Outcomes of synthetic biodegradable nanofiber polycaprolactone grafts are not inferior compared with the clinically used expanded polytetrafluoroethylene grafts after long-term implantation in the rat aorta. Moreover, these implants show better patency, compliance, endothelialization, and cell in-growth, and less intimal hyperplasia and calcification than their counterparts.

Diagnosis of and treatment for symptomatic carotid stenosis: an updated review

Carotid stenoses of ≥50% account for about 15–20% of strokes. Their degree may be moderate (50–69%) or severe (70–99%). Current diagnostic methods include ultrasound, MR‐ or CT‐angiography. Stenosis severity, irregular plaque surface, and presence of microembolic signals detected by transcranial Doppler predict the early recurrence risk, which may be as high as 20%. Initial therapy comprises antiplatelets and statins. Benefit of revascularization is greater in men, in older patients, and in severe stenosis; patients with moderate stenoses may also profit particularly if the plaque has an irregular aspect. An intervention should be performed within <2 weeks. In large randomized studies comparing endarterectomy and stenting, endovascular therapy was associated with a higher risk of periprocedural stroke, yet in some studies, with a lower risk of myocardial infarction and of cranial neuropathy. These trials support endarterectomy as the first choice treatment. Risk factors for each of the two therapies have been indentified: coronary artery disease, neck radiation, contralateral laryngeal nerve palsy for endarterectomy, and, elderly patients (>70 years), arch vessel tortuosity and plaques with low echogenicity on ultrasound for carotid stenting. Lastly, in direct comparisons, a contralateral occlusion increases the risk of periprocedural complications in both types of treatment.

Impact of anesthesia technique on the incidence of major complications after open aortic abdominal surgery: a cohort study

STUDY OBJECTIVE To determine the risk factors of perioperative complications and the impact of intrathecal morphine (ITM) in major vascular surgery. DESIGN Retrospective analysis of a prospective cohort. SETTINGS Operating room, intensive care unit, and Postanesthesia Care Unit of a university hospital. MEASUREMENTS Data from 595 consecutive patients who underwent open abdominal aortic surgery between January 1997 and December 2011 were reviewed. Data were stratified into three groups based on the analgesia technique delivered: systemic analgesia (Goup SA), thoracic epidural analgesia (Group TEA), and intrathecal morphine (Group ITM). Preoperative patient characteristics, perioperative anesthetic and medical interventions, and major nonsurgical complications were recorded. MAIN RESULTS Patients managed with ITM (n=248) and those given thoracic epidural analgesia (n=70) required lower doses of intravenous (IV) sufentanil intraoperatively and were extubated sooner than those who received systemic analgesia (n=270). Total inhospital mortality was 2.9%, and 24.4% of patients experienced at least one major complication during their hospital stay. Intrathecal morphine was associated with a lower risk of postoperative morbidity (OR 0.51, 95% CI 0.28 - 0.89), particularly pulmonary complications (OR 0.54, 95% CI 0.31 - 0.93) and renal dysfunction (OR 0.52, 95% CI 0.29 - 0.97). Other predictors of nonsurgical complications were ASA physical status 3 and 4 (OR 1.94, 95% CI 1.07 - 3.52), preoperative renal dysfunction (OR 1.61, 95% CI 1.01 - 2.58), prolonged surgical time (OR 1.78, 95% CI 1.16 - 2.78), and the need for blood transfusion (OR 1.77, 95% CI 1.05 - 2.99). CONCLUSIONS This single-center study showed a decreased risk of major nonsurgical complications in patients who received neuraxial analgesia after abdominal aortic surgery.

Isolated Bilateral Profunda Femoris Artery Aneurysm

BACKGROUND Isolated bilateral profunda femoris artery aneurysm (PFAA) is a very rare entity. Most of the cases are unilateral and occur with synchronous aneurysms elsewhere. Symptoms range from none to limb ischemia or hemorrhage because of rupture. METHODS We present a rare case of PFAA. In contrast to the general rule, the patient had a bilateral PFAA which was isolated to the deep femoral artery. The aneurysm was discovered after signs of acute limb ischemia caused by distal embolization. The patient was treated surgically with open aneurysmectomy and ligation of a branch of the deep femoral artery. CONCLUSION PFAA are asymptomatic most of the time. Surgical repair is always recommended to prevent such life-threatening complications. Different treatment modalities are offered, including endovascular options. The presence of a PFAA should prompt screening for concomitant aneurysms.

Validation of a rat model of cardiopulmonary bypass with a new miniaturized hollow fiber oxygenator

Cardiopulmonary bypass (CPB) is an essential component of cardiac surgery, with still unknown device/patient interactions. To evaluate the response of CPB to hemodynamic, biochemical, inflammatory, as well as thermo-pharmacodynamic interactions, a novel miniaturized oxygenator with controlled and standardized specifications has been developed together with an improved surgical central cannulation technique. A hollow-fiber small priming volume (6.3 ml) oxygenator was manufactured according to specifications resulting from engineering, heart surgery and perfusion expertise (Dideco-Sorin Group, Italy) with the following characteristics: Gas Exchange Surface—450 cm2, and Heat Exchange Surface— 16 cm2. The oxygenator was tested in vitro and in vivo in five anesthetized, ventilated, open-chest rats using a miniaturized roller pump. Pressures were monitored in the animal before and after the oxygenator. Central venous cannulation through the superior vena cava and aortic cannulation through the carotid artery were used. In vitro: blood oxygenation increased 10-fold (from room air to 100% O2) and PCO2 removal was 2.5-fold. In vivo: CPB was performed without blood prime for 90 minutes (no ventilation) maintaining stable hemodynamics. A maximal blood flow rate of 124 ml/min/kg was obtained. Arterio-venous PO2 gradients were 10-fold (O2 100%) with only small variations when changing blood flow rates. This new, standardized and miniaturized hollow fiber oxygenator, new cannulation technique and CPB circuit achieved optimal gas transfer with small asanguinous priming volumes. This study opens new potentials for various CPB-related study protocols in the small animal.

Ascending aorto-superior mesenteric artery bypass as a surgical option for revascularization in mesenteric ischemia associated with type B aortic dissection

We report the case of an acute ischemia of the superior mesenteric artery (SMA) after endovascular fenestration of a complicated acute type B aortic dissection. An initial attempt for endovascular revascularization of the SMA failed, and an ascending aorto-superior mesenteric artery bypass was urgently performed to salvage the small bowel. Surgery of patients in these specific settings is more complex because an adequate, more distal inflow vessel is often not present due to the dissected aorta and iliac arteries. This surgical option could be lifesaving and should be part of the vascular surgeons armamentarium.

Popliteal artery entrapment syndrome: report of two cases

Popliteal artery entrapment syndrome accounts for an important part of correctible causes of claudication and limb ischemia in young people. It is caused by an abnormal relation between the popliteal artery (PA) and the medial head of the gastrocnemius muscle. The diagnosis should be considered in any patient under 50 with calf claudication. The mainstay of treatment is prevention of PA fibrosis because if left untreated, the syndrome leads to irreversible damage to the PA with thrombosis and limb ischemia. We describe two cases of different types in 21- and 27-year-old males, respectively, and we review the literature about the presentation, diagnosis, classification and management of this entity.