Cannulation Of Vessels Research Articles

When it goes wrong: Complications of post-mortem CT angiography (PMCTA) as performed at VIFM

Introduction PMCTA is performed at VIFM for detection of bleeding sites. This presentation examines our PMCTA technique and analyses the reasons for incomplete performance and complications. Methods Review of all PMCTA records. CT images were compared with autopsy reports. Failure of PMCTA was defined as inadequate contrast filling of visceral and cerebral vessels including the site of suspected pathology. Complication was defined as iatrogenic vascular abnormality. Results 136 PMCTA performed since May 2010. Indications were subarachnoid hemorrhage (SAH) 39 (29%), haemopericardium 25 (18%), suspected GI hemorrhage (HGE) 17 (13%), intra-abdominal HGE 16 (12%), suspected pulmonary embolism 15 (11%) and other HGE 23 (17%). Autopsies were performed in 119 (88%). Failed and complicated PMCTA was observed in 53 cases (39%). These included inadequate filling of cerebral arteries 41 (30%), incorrect vessel cannulation 3 (2%), traumatic rupture of cannulated femoral vessel 3 (2%), iatrogenic arterial rupture due to over distension 3 (2%) and traumatic dissection of aorta. In 27 of 41 (66%) incomplete cerebral arterial filling occurred in cases of SAH. Discussion The inability to adequately fill intracranial arteries is an important deficiency in our technique especially given that SAH was a major indication in those cases. This failure seems to be a function of the raised intracranial pressure associated with SAH. Complications were considered largely technical and may have reflected inexperience of operators responsible for groin dissection or local variation in groin anatomy. Conclusion PMCTA as practiced at VIFM under performs especially in the cranial cavity for detecting causes of SAH possibly due to raised intracranial pressure. Meticulous dissection technique is required at the groin in order to avoid cannulation site complication.

High‐frequency micro‐ultrasound for vascular access in young children – a feasibility study by the High‐frequency UltraSound in Kids studY (HUSKY) group

Cannulation of small arteries and veins in young children can be challenging. Although anesthesiologists frequently use ultrasound for placement of central venous lines and nerve blocks, its use for cannulation of small, peripheral vessels is less helpful. Ultrasound systems (7-15MHz) currently used in clinical practice focus poorly at the sub-10-mm space and thus lack the resolution to allow accurate ultrasound-guided cannulation of small vessels. High-frequency micro-ultrasound (HFMU) is a new technology that allows higher resolution (15-50MHz) compared with conventional ultrasound. Limited human studies have been performed thus far with HFMU, and none have been performed in young children or for vascular access. This study was conducted to determine the feasibility of using HFMU to visualize and cannulate peripheral arteries and central veins in children under the age of 6years old. The diameter of radial and ulnar arteries was also measured. The anesthesiologists involved in this study found the 50MHz HFMU probe useful for cannulation of peripheral arteries, especially in the youngest children. The higher-frequency probes were less helpful for internal jugular vein cannulation because it was not always possible to view the carotid artery while cannulating the vein. The experience gained in this feasibility study suggests that HFMU could be a valuable addition to our armamentarium for difficult vascular access in the future.

Robot-assisted Fenestrated Endovascular Aneurysm Repair (FEVAR) Using the Magellan System

A 67-year-old man underwent robot-assisted three-vessel fenestrated endovascular aneurysm repair (FEVAR) for a 7.3-cm juxtarenal aneurysm. The 6-F robotic catheter was manipulated from a remote workstation, away from the radiation source. Robotic cannulation of the left renal artery was achieved within 3 minutes. System setup time was 5 minutes. There were no postoperative complications. Computed tomography angiography performed at discharge and at 4-month follow-up confirmed target vessel patency with no evidence of an endoleak. Selective cannulation of target vessels during FEVAR using this novel technology is feasible. Endovascular robotics may have a role in simplifying complex endovascular tasks and potentially reducing radiation exposure to the operator.

A first-in-man study of the role of flexible robotics in overcoming navigation challenges in the iliofemoral arteries

Current interventional techniques rely heavily on operator familiarity with catheters and wires and on physician skills in effectively navigating through and managing target lesions. A novel robotic technology allows endovascular specialists to remotely control catheter tip deflection and advancement and to coordinate manipulation of currently available wires. The aim of this study was to successfully demonstrate feasibility and safety of navigation to and treatment of iliac and femoral artery lesions using Hansen Medical's vascular control catheter (VCC). A total of 20 limbs were included in this analysis for a first-in-man trial of the VCC and vascular catheter control system. The local Institutional Review Board approved the trial, and all patients included had symptomatic femoropopliteal occlusive disease. Preoperative imaging was available on all patients. Target lesions in the contralateral superficial femoral artery ranged from mild stenosis to chronic total occlusions (TransAtlantic Inter-Society A through D). Exclusion criteria included previously treated iliac and femoral lesions in the symptomatic leg and a body mass index >35. The operators comprised three experienced interventionalists (two vascular surgeons and an interventional radiologist) and a novice (cardiac surgeon). The primary end point of the study was to demonstrate successful cannulation of the target vessel (ie, navigation to the lesion with wire and catheter) with the Hansen VCC, with no device-related serious adverse events. Secondary end points were to assess the ability to treat lesions using the flexible catheter defined by successful insertion of a guidewire, angiography of the target vessel, delivery of balloon, and/or stent. Procedure times and radiation delivered were analyzed for the group and by operator, and t-test was performed to determine statistical significance. Complications were assessed by clinical examination and ultrasound. Lesions were successfully and safely cannulated in all limbs treated. The VCC performed as designed in all cases. All interventionalists, regardless of experience, navigated the VCC with ease. However, statistically significant differences in navigation time and radiation per case were observed between the experienced and inexperienced interventionalists. There were no access site complications (hematoma, thrombosis, pseudoaneurysm) as evaluated by ultrasound. This initial experience in flexible robotics demonstrates that this technology is both efficacious and safe in the arterial tree. Although robotics provides superior maneuverability compared with current techniques, endovascular experience is crucial to taking full advantage of the extra capabilities. Valuable future considerations will include off-the-wall (center lumen) navigation with three-dimensional imaging.

Ethicality of Heart Transplantation from Donation after Circulatory Death Donors

rd of transplants performed in the United Kingdom are now undertaken using organs obtained from DCD donors [1]. Historically, the transplantation of organs procured after cardiac arrest was instrumental in pioneering transplantation. The initial heart and liver transplants were performed using organs removed after death of the donor [2,3]. Prior to definition of criteria for brainstem death (BSD), cardiac arrest and loss of circulation were considered essential for confirmation of donor death. The practice of DCD organ donation has raised many ethical concerns and continues to have detractors. Loss of cardiac output and cessation of circulation are the principal requirements for certification of death in the DCD donor. The ethicality of resuscitating the heart in DCD donors has been questioned. It is suggested by some that “cardiac death” should be an irreversible occurrence. Once established it is argued that resuscitation of the heart by any means would potentially negate the diagnosis of death due to recovery of heart beat and restoration of circulation within the donor. The terminal event that precedes the decision to withdraw therapy in the majority of DCD donors is usually severe neurological injury. However, neurologic testing in these donors does not identify irreversible loss of brain-stem function. Consequently, conventional heart-beating cadaveric donation is not an option. The lack of a clear definition of death contributes towards further confusion. In a recent clinical case of human DCD heart resuscitation, we utilized an extracorporeal perfusion circuit to deliver oxygenated blood to the donor after circulatory arrest [4]. The commonest protocol for DCD organ procurement relies on the rapid infusion of cold preservation solution into the donor circulation with the aim of initiating organ protection and preservation through cooling of organs. More recently, the use of extracorporeal membrane oxygenation (ECMO to reperfuse the donor with normothermic oxygenated blood has also been undertaken on the basis that warm blood perfusion may be a physiologically more appropriate means for organ resuscitation and preservation [5,6]. Currently, this practice is limited to the procurement of the kidneys and liver. The majority of retrieval teams who undertake ECMO reperfusion of the DCD donor have achieved this through cannulation of peripheral vessels, most commonly the femoral artery and vein. Institution of ECMO leads to retrograde perfusion of the abdominal viscera. During the early experience with ECMO in DCD donors, cardiac resuscitation was observed upon reperfusion. As this was deemed unnecessary, specific measures were undertaken to depress cardiac activity including the establishment of systemic hyperkalemia to produce cardiac arrest. The deployment and inflation of intra-aortic balloon catheters for occlusion of the descending aorta was another means of preventing coronary reperfusion, whilst maintaining perfusion of transplantable abdominal organs [7,8]. There remain several important ethical issues relating to DCD heart resuscitation which require discussion and debate: 1.� The appropriateness of restoration of circulation and recovery of heart beat within the donor for purposes of organ resuscitation and evaluation of function 2.� The ethicality of pre-treatment of the donor prior to withdrawal of support to facilitate the organ retrieval and procurement process (i.e. systemic heparinization, insertion of vascular catheters for delivery of preservation solutions)

The wire is really easy to see (WIRES): sonographic visualization of the guidewire by novices

To determine whether novices can distinguish between properly and improperly placed guidewires in a vascular access model after only minimal training. This was a prospective study involving trainees with no previous training in sonographic guidewire visualization. A vascular access model was created with guidewires positioned inside or adjacent to simulated veins. Subjects were taught to scan each wire to determine its location. Afterward, participants scanned a test model of five vein-wire pairs and recorded their answers as "inside," "outside," or "unsure." The test characteristics of sonographic guidewire localization were determined using actual wire location as the criterion standard. Forty trainees (21 emergency medicine residents, 19 medical students) participated, and each examined five simulated veins. There were 156 true positives (intravascular wire correctly identified), 38 true negatives (extravascular wire correctly identified), 2 false negatives, 2 false positives, and 2 cases in which the participant marked "not sure," which were reclassified as false negatives. Test characteristics were sensitivity 97.5% (95% CI 93.3-99.2) and specificity 95.0% (95% CI 81.8-99.1). The overall accuracy was 97.0%. Sonographic guidewire visualization, a step recommended for ensuring proper vessel cannulation during central venous access, can be accomplished by novices with a high degree of accuracy.

An intra-arterial knotted guide wire.

Central access is essentially an integral part of critical care, both for invasive monitoring and therapeutic interventions. Seldinger technique is the method for the insertion of a central line. It requires the following steps: cannulation of vessel followed by guide wire insertion, dilation of the tract and the vessel and the insertion and securing of the central line followed its maintenance-each of this step has its own complication.

Abstract 2: Orexin-A Improves Arousal from Post--Cardiac Arrest Coma in a Rodent Model

Introduction: Coma after cardiac arrest (CA) is common and leads to suffering for patients while being an emotional and financial burden to families and society. Other than hypothermia, there is currently no therapy to improve neurological outcome after CA. The hypothalamic Orexin pathway provides a potential pharmacologic target towards improving arousal after coma. Hypothesis: Post-resuscitaion, Orexin-A intracerebroventricular (icv) infusion after bolus injection will provide immediate and long term term arousal after CA which can be assessed by quantitative EEG (qEEG) and behavioral testing (neurologic deficit scale; NDS). Methods: Rats (N=17; Adult Male Wistar; 300-350gms) were implanted with icv cannula attached to an osmotic pump. One week later, rats underwent baseline EEG followed by intubation, mechanical ventilation, cannulation of the femoral vessels, followed by 7 minutes of asphyxial cardiac arrest. Forty-five minutes after the resuscitation, rats were randomized to either Orexin-A (n=8) or saline (n=9) icv bolus and infusion. EEG was monitored continuously for 4 hours after CA, and for 30 minutes at 24hrs, 48hrs, 72hrs, and 12 days post-CA. NDS was also conducted at these times. EEG was analyzed using a custom algorithm to analyze the information quantity (IQ), an entropy based nonlinear measure for the entire frequency domain and clinical sub-bands. Results: Orexin-A treated rats demonstrated higher normalized IQ immediately after receiving the Orexin-A in comparison to saline (0.731±0.028[AM1] vs. 0.613±0.021; p<0.01). This acute improvement in IQ sustained for 4hrs Post-CA. Moreover, the band-specific analysis [RG2] showed that Orexin-A improved the IQ in β-band at 72hrs (1.160±0.039 vs. 1.052±0.029; p<0.05). Behaviorally, Orexin-A allows rats to perform significantly better on the NDS at 4hrs (38.3±3.2 vs. 30.1±1.9; p<0.05); 24hrs (67.1±4.1 vs. 49.8±3.8; p<0.01); 48hrs (73.4±4.3 vs. 61.0±3.6; p<0.05), and 72hrs (75.0±3.3 vs. 65.2±2.9; p<0.05). Conclusions: Rats receiving icv Orexin-A post-CA showed better arousal on both qEEG and behavioral (NDS) testing. Orexin-A may have therapeutic potential in disorders of arousal and coma after CA.

Temporary axillobifemoral bypass during fenestrated aortic aneurysm repair

Fenestrated endovascular aortic aneurysm repair (f-EVAR) of juxtarenal aneurysms requiring cannulation of the superior mesenteric artery and renal arteries is technically challenging, has a long operating time, and requires bilateral large-caliber sheath insertion into the femoral arteries. Consequently, the risk of lower limb ischemia and subsequent reperfusion injury is increased. We describe the use of an adjunct temporary axillobifemoral bypass graft (TABFBG) for f-EVAR and propose that it be used as a strategy to avoid ischemia-reperfusion injury in patients anticipated as being at increased risk. Consecutive patients from a tertiary referral center undergoing f-EVAR, between October 2008 and August 2011, were retrospectively analyzed. Patients with lower limb arterial occlusive disease and those with difficult anatomy had an adjunct TABFBG. All patients presenting with a juxtarenal aortic aneurysm were treated endovascularly, regardless of aneurysm anatomy and technical difficulties. There were 37 patients without TABFBG (group 1) and 27 with TABFBG (group 2). No patients required open conversion. Sex and age were not significantly different between the groups. The median ankle-brachial pressure index was significantly higher in group 1 (P=.0001). The groups had similar median blood loss, percentage of target vessel cannulation, and median stay in the intensive therapy unit. Morbidities were similar in both groups. There were no significant differences in cardiac, renal, or respiratory complications between the groups. The 30-day mortality was 10.8% (n=4) in group 1 and 0% in group 2 (P=.046). Our series has demonstrated a significant reduction in mortality (10.8% absolute risk reduction) and no increase in morbidity with the use of a TABFBG for fenestrated grafts. This is likely a result of the reduction in ischemia and ischemia-reperfusion injury in these patients. We therefore recommend the use of TABFBG in patients with proximal severe stenotic or occlusive disease and those in whom an operative time of >4 hours is predicted (typically those for whom three or more target fenestrations is planned).

Cerebral and Lower Limb Near‐Infrared Spectroscopy in Adults on Extracorporeal Membrane Oxygenation

Percutaneous femoral venoarterial (VA) or jugular venovenous (VV) extracorporeal membrane oxygenation (ECMO) can result in delivery of hypoxic blood to the brain, coronaries, and upper extremities. Additionally, VA-ECMO by percutaneous femoral artery cannulation may compromise perfusion to the lower limbs. Use of near-infrared spectroscopy (NIRS) detects regional ischemia and warns of impending hypoxic damage. We report the first known series with standardized monitoring of this parameter in adults on ECMO. This is an institutional review board-approved single institution retrospective review of patients with NIRS monitoring on ECMO from July 2010 until June 2011. Patients were analyzed for drops in NIRS tracings below 40 or >25% from baseline. VA-ECMO and VV-ECMO were initiated by percutaneous cannulation of the femoral vessels and the internal jugular vein, respectively. Sensors were placed on the patients' foreheads and on the lower limbs. NIRS tracings were recorded, analyzed, and correlated with clinical events. Twenty patients were analyzed (median age: 47.5 years): 17 patients were placed on VA-ECMO, and three patients on VV-ECMO. The median duration on ECMO was 7 days (range 2-26). One hundred percent of patients had a significant drop in bilateral cerebral oximetry tracings resulting in hemodynamic interventions, which involved increasing pressure, oxygenation, and/or ECMO flow. In 16 patients (80%), these interventions corrected the underlying ischemia. Four patients (20%) required further diagnostic intervention for persistent decreased bilateral and/or unilateral cerebral oximetry tracings, and were found to have a cerebrovascular accident (CVA). Six (30%) patients had persistent unilateral lower limb oximetry events, which resolved upon placement or replacement of a distal perfusion cannula. No patient was found to have either lower limb ischemia or a CVA with normal NIRS tracings. Use of NIRS with ECMO is important in detecting ischemic cerebral and peripheral vascular events. This allows for potential correction of the underlying process, thus preventing permanent ischemic damage.

Three new techniques for creation of a steerable sheath, a 4F snare, and bidirectional sheath inversion using existing endovascular materials

We present three novel techniques for creation of (1) a steerable sheath, (2) a 4F snare device, and (3) dual anterograde and retrograde double-wire percutaneous transluminal angioplasty access technique using a single femoral puncture. These techniques were conceived and bench-tested in our institution, allowing the utilization of inexpensive equipment for complicated endovascular procedures. They offer (1) controlled navigation, no-touch vessel cannulation and cannulation of angulated vessels, contralateral limb of stent grafts, fenestrations, and branches; (2) a low-profile (4F external diameter) modifiable snare with the ability to expand to the size of an entire aneurysm and the ability to undo the snare in case of blockage with other endovascular material; and (3) in situ sheath inversion for concomitant anterograde and retrograde percutaneous angioplasty with a single femoral puncture.

A novel mouse model of isolated limb perfusion for extremity melanoma

BackgroundIsolated limb perfusion (ILP) for extremity melanoma has been used clinically for over half a century. Mouse modeling of ILP may offer significant experimental advantages compared with existing models. We propose a novel mouse model and report our initial experience. MethodsWe injected female C57BL/6 mice (22–25 g) with 1 × 106 B16 melanoma cells subcutaneously in the distal right thigh. After 7 d of tumor establishment, we cannulated the superficial femoral artery (inflow) and vein (outflow) of anesthetized mice and placed a proximal tourniquet. Non-oxygenated perfusate included low-dose or high-dose melphalan and saline (control). We analyzed endpoints of cannulation time, procedural complications, morbidity, toxicity, and tumor response. ResultsWe performed 11 superficial femoral vessel cannulations. Median cannulation time was 19 min (range, 15–32 min). Intact perfusion models were obtained in 10 of 11 cases (91%); one case failed owing to superficial femoral vein dissection. Morbidity rate was 20% (one wound dehiscence and one hematoma). Both high- and low-dose melphalan perfusion groups (4 mice/group) trended to growth delay and regression compared with saline-perfused groups. Toxicity was greater in the high-dose melphalan-treated mice. ConclusionsWe have established the first reproducible mouse model of ILP for melanoma. Future experiments will take advantage of the large number of established mouse knockout models and reagents to dissect the precise mechanisms of tumor control after ILP, and examine to novel agents.

Anatomical examination of the great inguinal blood vessels in preterm and term neonates

It is generally accepted that vessel cannulation is technically more difficult and results in more complications in neonates. A sound anatomical knowledge of the inguinal area is therefore important in the selection of appropriately sized central line catheters as well as the approach to central vessel access. Eleven stillborns were investigated. Birth weight (mean: 2,414 g, 900-4,100 g) and gestational age (mean 34 1/7 weeks', 27 6/7-42 1/7) varied within normal range. The outer diameters of the femoral artery (FA), femoral vein (FV), and great saphenous vein (GSV) were determined. The distance between the anterior superior iliac spine and the pubic tubercle was set as 100% and the vessel intersection points were calculated as percentage values of the inguinal ligament length, starting at the iliac spine. The FA has a diameter of 1.9 ± 0.5 mm without correlation to gestational age. The FA crosses the inguinal ligament centrally. The FV has a diameter of 3.1 ± 1.0 mm and does have correlation to gestational age. The FV crosses the inguinal ligament at 63-64%. The GSV has a diameter of 1.4 ± 0.7 mm. Its point of intersection at the level of the inguinal ligament is 68-70%. We conclude that cannulation of the femoral artery or vein should not be performed too far (<1 cm) from the inguinal ligament. The course of the GSV is not suitable for catheter insertion.

Adjunctive ultrasonography during carotid artery stenting to minimize iodine contrast use

Carotid artery stenting (CAS) in patients with chronic kidney disease carries a significant risk of contrast-induced nephropathy. We report a case of CAS with adjunctive sonography to reduce the amount of contrast medium during angiography. A 71-year-old man presented with a symptomatic right carotid stenosis. He was selected for CAS due to significant medical comorbidity, which included severe renal impairment. A preoperative noncontrast CT was performed to assess anatomical suitability and to plan arch vessel cannulation. We undertook CAS with the use of intraoperative ultrasound. Sonography was used to monitor the manipulation of wires, catheters, and stents. Four milliliters of contrast was required to complete the procedure successfully with no deterioration in postoperative renal function. Adjunctive ultrasound is feasible to reduce contrast use in patients with severe renal impairment undergoing CAS.

Modified vaccinia virus Ankara-based vaccine vectors induce apoptosis in dendritic cells draining from the skin via both the extrinsic and intrinsic caspase pathways, preventing efficient antigen presentation.

Dendritic cells (DC) are potent antigen-presenting cells and central to the induction of immune responses following infection or vaccination. The collection of DC migrating from peripheral tissues by cannulation of the afferent lymphatic vessels provides DC which can be used directly ex vivo without extensive in vitro manipulations. We have previously used bovine migrating DC to show that recombinant human adenovirus 5 vectors efficiently transduce afferent lymph migrating DEC-205(+) CD11c(+) CD8(-) DC (ALDC). We have also shown that recombinant modified vaccinia virus Ankara (MVA) infects ALDC in vitro, causing downregulation of costimulatory molecules, apoptosis, and cell death. We now show that in the bovine system, modified vaccinia virus Ankara-induced apoptosis in DC draining from the skin occurs soon after virus binding via the caspase 8 pathway and is not associated with viral gene expression. We also show that after virus entry, the caspase 9 pathway cascade is initiated. The magnitude of T cell responses to mycobacterial antigen 85A (Ag85A) expressed by recombinant MVA-infected ALDC is increased by blocking caspase-induced apoptosis. Apoptotic bodies generated by recombinant MVA (rMVA)-Ag85A-infected ALDC and containing Ag85A were phagocytosed by noninfected migrating ALDC expressing SIRPα via actin-dependent phagocytosis, and these ALDC in turn presented antigen. However, the addition of fresh ALDC to MVA-infected cultures did not improve on the magnitude of the T cell responses; in contrast, these noninfected DC showed downregulation of major histocompatibility complex class II (MHC-II), CD40, CD80, and CD86. We also observed that MVA-infected ALDC promoted migration of DEC-205(+) SIRPα(+) CD21(+) DC as well as CD4(+) and CD8(+) T cells independently of caspase activation. These in vitro studies show that induction of apoptosis in DC by MVA vectors is detrimental to the subsequent induction of T cell responses.

Transbrachial intra-aortic balloon pumping for a patient with fulminant myocarditis

A 57-year-old man with acute myocarditis was transferred to our hospital from a local clinic. The patient experienced unexpected sudden cardiac arrest 16 h after admission. Mechanical cardiopulmonary support was started using percutaneous cardiopulmonary support, intra-aortic balloon pumping (IABP), continuous hemodialysis filtration, and temporary cardiac pacing with percutaneous cannulation of the femoral vessels. Hematoma developed at the IABP insertion site on the 5th day after admission. The IABP was removed, and another IABP system was inserted via the left brachial artery. The patient's condition improved, and the IABP was removed on the 9th day after admission. The remainder of the patient's in-hospital treatment was uneventful, and he showed near-normal left ventricular systolic function 1 year after discharge.

Quantification of the endothelial surface glycocalyx on rat and mouse blood vessels

The glycocalyx on the surface of endothelium lining blood vessel walls modulates vascular barrier function, cell adhesion and also serves as a mechano-sensor for blood flow. Reduction of glycocalyx has been reported in many diseases including atherosclerosis, inflammation, myocardial edema, and diabetes. The surface glycocalyx layer (SGL) is composed of proteoglycans and glycosaminoglycans, of which heparan sulfate is one of the most abundant. To quantify the SGL thickness on the microvessels of rat mesentery and mouse cremaster muscle in situ, we applied a single vessel cannulation and perfusion technique to directly inject FITC-anti-heparan sulfate into a group of microvessels for immuno-labeling the SGL. We also used anti-heparan sulfate for immuno-labeling the SGL on rat and mouse aortas ex vivo. High resolution confocal microscopy revealed that the thickness of the SGL on rat mesenteric capillaries and post-capillary venules is 0.9±0.1μm and 1.2±0.3μm, respectively; while the thickness of the SGL on mouse cremaster muscle capillaries and post-capillary venules is 1.5±0.1μm and 1.5±0.2μm, respectively. Surprisingly, there was no detectable SGL in either rat mesenteric or mouse cremaster muscle arterioles. The SGL thickness is 2.5±0.1μm and 2.1±0.2μm respectively, on rat and mouse aorta. In addition, we observed that the SGL is continuously and evenly distributed on the aorta wall but not on the microvessel wall.

Experimental Endoscopic Endovascular Cannulation: A Novel Approach to Thrombolysis in Retinal Vessel Occlusion

Recent studies suggest that the cannulation of retinal vessels may provide a potential access route for the administration of thrombolytic agents in retinal vessel occlusion. However, the major problem with available techniques is the limited visualization of retinal vessels with conventional surgical microscopes, making it difficult to effectively control the targeted injection of drugs. The authors developed a novel single-piece catheter system for the endoscopically guided puncture of microvessels. Experimental punctures of retinal vessels with injection of fluid were performed in porcine cadaver eyes using a standard high-resolution gradient index microendoscope introduced through the pars plana. Endoscopically guided punctures were successfully performed in porcine branch retinal veins at various distances from the optic disc. Injection of recombinant tissue plasminogen activator (rt-PA), hypertonic solution (hyper HES), or normal saline solution into the vessel lumen was accomplished under direct endoscopic view in a safe and reliable manner. Endoscopically guided puncture of retinal microvessels is feasible and can be performed through a pars plana entry without additional micromanipulation devices. This novel technique may be a safe and effective approach to catheter-directed endovascular thrombolysis in retinal vascular occlusive diseases.

Extracorporeal membrane oxygenation support improves survival of patients with Hantavirus cardiopulmonary syndrome refractory to medical treatment☆

The aim of the study was to evaluate the outcome of extracorporeal membrane oxygenation (ECMO) support in Hantavirus cardiopulmonary syndrome (HCPS) patients with a predicted mortality of 100%, and the complications associated with this treatment modality and different cannulation techniques. A total of 51 patients with refractory HCPS were supported with ECMO between April 1994 and June 2010. They were divided into group A consisting of the 26 patients treated between 1994 and 2000 and group B consisting of 25 patients treated between 2003 and 2010. No patients were treated between September 2000 and December 2003. Patients in group A were intubated when they became hypoxic and placed on ECMO when they became hemodynamically unstable, whereas patients in group B had elective insertion of vascular sheaths and were almost concurrently intubated and placed on ECMO when they decompensated. Cannulation of the femoral vessels was performed percutaneously in 18 (35.3%) patients and with an open technique in 33 (64.7%) patients. Complications from percutaneous cannulation occurred in 4/18 (22.27%) patients: retroperitoneal hematoma in 2/18 (11.1%) and lower-extremity ischemia in 2/18 (11.1%) patients. Complications from open femoral cannulation occurred in 12/33 (36.3%) patients: bleeding in 10/33 (30.3%) patients and ischemia in 2/33 (6.1%) patients. The overall survival was 66.6% (34 of 51 patients); 56% (14/26) for group A and 80% (20/25) for group B (p = 0.048). There was no difference in mortality regarding the method of cannulation. A trend toward increased mortality in patients with cannulation complications was recognized, but it was not statistically significant. Mortality was not associated with ECMO duration (average 121.7h, range: 5-276h). All survivors recovered and were discharged from the hospital after a mean hospital stay of 19.8 days (range: 10-39 days). Two-thirds of 51 HCPS patients with a predicted mortality of 100%, who were supported with ECMO, survived and recovered completely. Survival was significantly higher in the second half of the study. Complications associated with both types of femoral cannulation were associated with a trend toward decreased survival, which was not significant.

Magnetic Resonance Imaging to Guide Surgical Practice

Magnetic resonance (MR) imaging can provide functional and anatomical information in a single non-ionising examination and represents a rapidly expanding area of innovation and technology research. The lymphatic system is a complex network of lymph vessels, nodes and organs, and is essential for the maintenance of fluid homeostasis and immunocompetence. Failure of lymph clearance from the limb can be caused bycongenital absence of lymph vessels or valve incompetence, which are relatively uncommon compared to acquired obliteration of the lymph vessels (infection, trauma, radiotherapy) and obstruction of the lymph nodes by primary and secondary malignant disease, and nodal hilar fibrosis. Adequate imaging of the lymphatic system in the lower limbs should therefore be able to delineate the anatomy of the lymph vessels and nodes, both proximal and distal to the area of interest, and also provide functional information on the rate of lymph clearance. X-ray lymphangiography was one of the first techniques developed to visualise the lymphatics. 1 Patent blue dye is first injected subcutaneously into each of the web spaces in the foot (visual lymphangiography), to stain and localise the deep lymphatic vessels. The skin on the dorsum of the footis then incised and a large lymph vessel is cannulated. Oily X-ray contrast medium is injected directly into the lymph vessel and serial images are acquired; initial images show the lymph vessels whereas later ones delineate the lymph nodes. Abdominal films are required for the iliac and aortic lymph nodes and a chest film to assess the thoracic duct. This technique can give high spatial resolution anatomical and functional information, however it is hampered by: the use of ionising radiation; a single vessel is cannulated and so only some of the lymph vessels are shown; the 2D acquisition is a projection and therefore some vessels may be superimposed on others; the procedure is relatively invasive; the injected contrast media may cause inflammation and fibrosis of the lymph vessels; pulmonary complications such as pulmonary embolus and adult respiratory distress syndrome have been reported; and the contrast media may take several years to be removed from the body. 2e4