Selective Vascular Occlusion Research Articles

Combining a small urinary catheter with an endo mini-retractor: a novel technique for laparoscopic selective vascular control

The Pringle maneuver using a urinary catheter has been described and proven to be one of the best methods for laparoscopic intracorporeal vascular control. Selective vascular control provides many advantages over total inflow occlusion by the Pringle maneuver. However, laparoscopic selective vascular control by urinary catheter has not been described. We, herein, describe laparoscopic selective vascular control using a combined small urinary catheter with an endo mini-retractor, which inserted in a new way, named ‘The J-shaped Loop’. This method makes the instrument more compact so we can selectively control the vascular pedicle. When selective vascular occlusion is desired, the loop is tightened and the tension is held just by the catheter itself. This novel technique is simple, safe, effective and reproducible, and, therefore, can be used as a good alternative to other intracorporeal techniques for laparoscopic liver resection.

Intraoperative Assessment of the Demarcation Line and Intersegmental/Sectional Planes in Liver Surgery

Purpose: Intraoperative assessment of demarcation line (DL) and intersegmental/sectional planes (IP) is essential to perform accurate liver resection without ischemic areas and venous congestion. DL is the most important landmark on the liver surface. The DL is normally formed by means of selective vascular occlusion or portal staining using a dye, and it can be recognized by surgeons’ eye. However, direct visualization with surgeons’ eye suffers from the failing of the evaluation due to an unclear DL, especially in patients with cirrhotic or steatotic livers. Currently, IP, which cannot be recognized by direct visualization, is now in the spotlight during parenchymal transection. Herein, we assessed the DL and IP intraoperatively by several imaging modalities. Method: The DL and IP were intraoperatively detected by means of conventional demarcation techniques and several imaging modalities as follows during liver surgery in a human and an animal model. 1. Direct visualization 2. Indocyanine green fluorescence imaging (ICG-FI) 3. Contrast-enhanced intraoperative ultrasonography (CE-IOUS) 4. Contrast-enhanced intraoperative ultrasonic cholangiography (CE-IOUSC) 5. Augmented Reality using preoperative data (AR) 6. Hyperspectral imaging (HSI) Results: The DL was detected by direct visualization, ICG-FI, and HSI. AR detected virtual DL. On the other hand, the IP was detected by ICG-FI, CE-IOUS, and CE-IOUSC. In this time, we will show the current status and issues with discussion about the strong and weak points of them. Conclusion: New technologies for assessment of DL and IP have a great potential to provide more information to surgeons in order to standardize the surgical approach and develop new surgical approaches.

Demarcation Line Assessment in Anatomical Liver Resection: An Overview

Anatomical liver resection (ALR) is the preferred oncological approach for the treatment of primary liver malignancies, such as hepatocellular carcinoma and intrahepatic cholangiocarcinoma. The demarcation line (DL) is formed by means of selective vascular occlusion and is used by surgeons to guide ALR. Emerging intraoperative technologies are playing a major role to enhance the surgeon's vision and ensure a precise oncologic surgery. In this article, a brief overview of modalities to assess the DL during ALRs is presented, from the established conventional techniques to future perspectives.

Conservation of both hematocrit and liver regeneration in hepatectomies: a vascular occlusion approach in rats.

ABSTRACT Background: Hepatectomies promote considerable amount of blood loss and the need to administrate blood products, which are directly linked to higher morbimortality rates. The blood-conserving hepatectomy (BCH) is a modification of the selective vascular occlusion technique. It could be a surgical maneuver in order to avoid or to reduce the blood products utilization in the perioperative period. Aim: To evaluate in rats the BCH effects on the hematocrit (HT) variation, hemoglobin serum concentration (HB), and on liver regeneration. Methods: Twelve Wistar rats were divided into two groups: control (n=6) and intervention (n=6). The ones in the control group had their livers partially removed according to the Higgins and Anderson technique, while the rats in the treatment group were submitted to BCH technique. HT and HB levels were measured at day D0, D1 and D7. The rate between the liver and rat weights was calculated in D0 and D7. Liver regeneration was quantitatively and qualitatively evaluated. Results: The HT and HB levels were lower in the control group as of D1 onwards, reaching an 18% gap at D7 (p=0.01 and p=0.008, respectively); BCH resulted in the preservation of HT and HB levels to the intervention group rats. BCH did not alter liver regeneration in rats. Conclusion: The BCH led to beneficial effects over the postoperative HT and serum HB levels with no setbacks to liver regeneration. These data are the necessary proof of evidence for translational research into the surgical practice. : A) Unresected liver; B) liver appearance after the partial hepatectomy (1=vena cava; 2=portal vein; 3=hepatic vein; 4=biliary drainage; 5=hepatic artery)

Mesohepatectomy for centrally located large hepatic tumors: a report of 37 patients

Objective To evaluate the safety of mesohepatectomy for centrally located large hepatic tumors. Methods The clinical data of 37 patients who underwent hepatectomy for centrally located large liver tumors in our hospital from October 2010 to August 2015 were retrospectively analyzed. During the operation, the left and right hemilivers were mobilized. Slings for the improved liver hanging maneuver and for selective hepatic vascular occlusion were placed. These slings were used when necessary in order to minimize occlusion and ischemia time to the residual liver, and to maximize the volume of functional liver remnant. Mesohepatectomy was carried out using a microwave hemostatic separator. The feasibility, its effects on preventing hemorrhage, the degree of liver damage and the postoperative complications were evaluated. Results The mean diameter of the neoplasms was (12.6±7.2) cm. The vascular inflow occlusion time of the left and right hemilivers were (12.2±3.5) min and (18.5±7.1) min, respectively. The blood loss was (487±352) ml. The amount of red blood cell transfusion was (2.7±1.9) U. The operation time was (215±72) min. TBIL, ALT and AST reached their peak levels on the 1st day after operation and they were higher than before surgery (P 0.05). The initial increase in ALT was quick and then it slowed down, while the initial increase in AST was slow but it decreased quickly. Conclusions Mesohepatectomy for centrally located large hepatic tumors could safely be carried out using the liver hanging maneuver combined with selective hepatic vascular occlusion and a microwave hemostatic separator. This method has the advantages of causing less bleeding, liver damage and rapid recovery. Key words: Liver neoplasms; Mesohepatectomy; Liver hanging maneuver; Hepatic vascular occlusion

Isolated complete resection of hepatic caudate lobe: a clinical experience of 14 patients

Objective To summarize the clinical experience with isolated complete resection of hepatic caudate lobe in 14 patients. Methods The clinical data of 14 patients with isolated complete resection of hepatic caudate lobe carried out in our hospital from December 2007 to March 2015 were retrospectively analyzed. During the operation, selective hepatic vascular occlusion slings, and supra- and infra-hepatic inferior vena cava slings were placed after full mobilization of the liver. Isolated complete resection of the hepatic caudate lobe was performed through the left and/or the right, the anterior liver-splitting or the retrograde approaches. Results The mean operation time was (227±64) min. The mean amount of blood loss was (530±325) ml. The mean vascular occlusion time was (19.5±18.6) min. The mean diameter of neoplasm was (15.4±9.2) cm. All the operations were successfully carried out. There were no massive hemorrhage, bile leakage or perioperative death. Hydrothorax occurred in 3 patients and ascites in 2. The mean stay in hospital was (21±9) days. All the patients were cured and discharged home. Conclusion Isolated complete resection of hepatic caudate lobe was feasible in clinical practice. Key words: Hepatic caudate lobe; Liver neoplasms; Hepatectomy

Intraoperative Hemifacial Composite Flap Perfusion Assessment Using Spatial Frequency Domain Imaging: A Pilot Study in Preparation for Facial Transplantation.

Vascularized composite allotransplantation represents an important advancement in the field of reconstructive microsurgery and has continued to increase in popularity. The significant clinical morbidity associated with flap failure represents an important barrier to even more widespread use of these techniques. Early identification of vascular compromise has been associated with a higher salvage rate, yet most surgeons rely only on clinical assessment intraoperatively. Spatial frequency domain imaging (SFDI) presents a noncontact, objective measurement of tissue oxygenation over a large field of view. This study aims to evaluate the use of SFDI technology in hemifacial composite flap compromise as could occur during facial transplant. Six composite hemifacial flaps were created in three 35-kg Yorkshire pigs and continuously imaged using SFDI before, during, and after 15-minute selective vascular pedicle occlusion. Arterial and venous clamping trials were performed for each flap. Changes in oxyhemoglobin concentration, deoxyhemoglobin concentration, and total hemoglobin were quantified over time. The SFDI successfully measured changes in oxygenation parameters in all 6 composite tissue flaps. Significant changes in oxyhemoglobin, deoxyhemoglobin, and total hemoglobin were seen relative to controls. Early and distinct patterns of alteration were noted in arterial and in venous compromise relative to one another. The need for noninvasive, reliable assessment of composite tissue graft viability is apparent, given the morbidity associated with flap failure. The results of this study suggest that SFDI technology shows promise in providing intraoperative guidance with regard to pedicle vessel integrity during reconstructive microsurgery.

Effect of preoperative transcatheter arterial chemoembolization on the perioperative outcome of patients with hepatocellular carcinoma

To explore the surgical risk, perioperative outcome and the response of patients with hepatocellular carcinoma (HCC) after preoperative transcatheter arterial chemoembolization (TACE). A retrospective case-matched study was conducted to compare the characteristics and corresponding measures of patients in the preoperative TACE group and the control group without TACE. A total of 105 patients (82 patients with selective and dynamic region-specific vascular occlusion to perform hepatectomy for patients with complex hepatocellular carcinoma) was included in this study, in which 35 patients underwent TACE therapy, and a 1:2 matched control group of 70 subjects. The patients of preoperative TACE therapy group had a higher level of γ-glutamyl transpeptidase before operation (119.52±98.83) U/L vs. (67.39±61.25) U/L (P=0.040). The operation time was longer in the TACE group than that in the control group but with a non-significant difference (232.60±95.43) min vs. (218.70±75.13) min (P=0.052). The postoperative recovery of liver function and severe complications in the preoperative TACE group were similar to that in the control group (P>0.05). There were no massive hemorrhage, biliary fistula and 30-d death neither in the treatment group and matched control group. Preoperative TACE therapy has certain negative effect on liver function. It is preferable to use selective and dynamic region-specific vascular occlusion technique during hepatectomy and combine with reasonable perioperative treatment for this group of patients, that can ensure safety of patients and promote their rapid recovery.

Application of selective semi-hepatic vascular occlusion combined with low central venous pressure in hepatectomy

Application of selective semi-hepatic vascular occlusion combined with low central venous pressure in hepatectomy

Effects of selective hepatic vascular occlusion on the prognosis of patients undergoing hepatic resection for huge liver cancer

Objective To evaluate the effects of selective hepatic vascular occlusion SHVO) on the prognosis of patients undergoing hepatic resection for huge liver cancer.Methods The clinical data of 49 patients who received huge liver cancer resection at the Zhejiang People's Hospital from January 2005 to January 2010 were retrospectively analyzed.Based on the type of hepatic vascular occlusion,all patients were divided into Pringle's maneuver group (24 patients) and SHVO group (25 patients).The intraoperative condition,postoperative recovery of hepatic and renal function,incidence of complications,survival rate and recurrence rate of liver cancer of the 2 groups were compared.All data were analyzed by using the t test or Fisher exact probability.The survival curve was drawn by using the Kaplan-Meier method and the survival of the 2 groups was compared by using the Log-rank test.Results Hepatectomy was successfully performed on all the patients.Time for blood occlusion were (32 ±19) minutes in the Pringle's maneuver group and (34 ± 22)minutes in the SHVO group,with no significant difference between the 2 groups (t =2.45,P ＞ 0.05).The volume of blood loss of the Pringle's maneuver group was (736 ± 543) ml,which was significantly greater than (273 ± 298) ml of the SHVO group (t =6.87,P ＜0.05).The incidences of hepatic vein rupture were 21％ (5/24) in the Pringle's maneuver group and 24％ (6/25)in the SHVO group,with no significant difference (x2=1.45,P＞0.05).The course of 3 patients was complicated by hepatic vein rupture and hemorrhage and 1 by air embolism in the Pringle's maneuver group,while no hemorrhage or air embolism happened in the SHVO group.Four patients in the Pringle's maneuver group and 3 in the SHVO group were found with vascular invasion,while the resection margins were negative.There was no significant difference in the hepatic function in the 2 groups before operation.The levels of alanine aminotransferase in the SHVO group at postoperative day 1 and 3 were significantly lower than those in the Pringle's maneuver group (t=7.12,6.35,P ＜ 0.05).There was no significant difference in the levels of blood urea nitrogen and creatinine between the 2 groups (P ＞ 0.05).Acute hepatic dysfunction was found in 4 patients in the Pringle's maneuver group,but no patients with acute hepatic dysfunction was found in the SHVO group.The 1-and 3-year tumor-free survival rates were 58％ and 21％ in the Pringle's maneuver group,which were significantly lower than 72％ and 30％ in the SHVO group (x2 =5.32,6.07,P ＜ 0.05).The 5-year tumor-free survival rates were 21％ in the Pringle's maneuver group and 20％ in the SHVO group,with no significant difference between the 2 groups (x2 =1.78,P ＞ 0.05).Conclusion SHVO is safe,feasible and effective to prevent hemorrhage and postoperative acute hepatic dysfunction,and it is also helpful in reducing early-stage tumor recurrence and improving the tumor-free survival rate in patients with huge liver cancer. Key words: Liver neoplasms; Hepatectomy ; Hepatic vascular occlusion ; Recurrence

Perioperative Analysis of Laparoscopic Liver Resection with Different Methods of Hepatic Inflow Occlusion

During liver resection, bleeding remains the most important challenge. A reduction in blood loss and avoiding the need for a blood transfusion are important objectives for liver surgeons today. The authors compared the intra- and postoperative course of patients undergoing laparoscopic liver resections under intermittent total pedicle occlusion (IPO), hemihepatic vascular occlusion (HVO), and selective vascular occlusion (SVO). Retrospective analysis was conducted of patient data from 41 cases of laparoscopic liver resection in three groups of patients under different occlusion methods, including 15 cases of IPO, 15 cases of HVO, and 11 cases of SVO. The advantages and disadvantages of the various methods were compared, as well as blood loss, operation time, changes in postoperative liver function, and complications. There was no operative death in any of the 41 patients. Generally, there was no significant difference among the three groups in blood loss, clamping time, or operative time. After the operation, the effect on liver function for the HVO and SVO groups was significantly less severe than that for the IPO group (P<.05). The incidence of postoperative complications was mainly related to IPO and the larger amount of bleeding. Both HVO and SVO are feasible in laparoscopic hepatectomy and have the advantage of reducing liver remnant ischemia injury and modality rate over IPO. HVO is easy to do for left lateral lobe or resection of the left half of the liver. SVO is suitable for right lobe resection.

Control of the inflow and outflow system during liver resection

Control of blood loss is a serious problem during liver resection. Bleeding from the inflow system can be controlled by the Pringle maneuver. The time limit for clamping is up to 10-15min. A shortcoming of the Pringle maneuver is that it causes blood congestion in the portal vein. To avoid this problem other techniques have been developed including selective vascular occlusion and selective clamping of segmental branches. Bleeding from the outflow system is closely related to central venous pressure (CVP). Lowering the CVP reduces blood loss; in particular, keeping CVP <5cmH(2)O by anesthesiological management is a simple and effective way to reduce blood loss. CVP remains high in some cases despite anesthesiological efforts, but in these circumstances other techniques are available including inferior vena cava clamping below the liver and intraoperative blood salvage.

Using synergistic effects in targeting angiogenesis: combination therapy for corneal neovascularization

Evaluation of: You IC, Im SK, Lee SH, Yoon KC. Photodynamic therapy with verteporfin combined with subconjunctival injection of bevacizumab for corneal neovascularization. Cornea 30(1), 30–33 (2011).Corneal neovascularization occurs following infectious, ischemic, inflammatory and other corneal diseases, as well as corneal injuries. It has a detrimental effect on visual acuity and also presents a significant risk for the failure of corneal grafting. To date, the therapeutic modalities are limited and address either the underlying inflammatory and infectious processes or selectively ablate those vessels using photocoagulation or diathermy. More recent strategies include pharmacological inhibition of various steps of angiogenesis and selective photochemical vascular occlusion with photodynamic therapy. The article under evaluation presents a prospective, interventional case series treating corneal neovascularization with a combination of photodynamic therapy and subconjunctival injection of bevacizumab (Avastin™, Genentech Inc., CA, USA). The authors reported success with complete occlusion of vessels in 66.7% of patients at 1 year following a single-session treatment. As with the success seen in treating choroidal neovascularization, this combined approach may offer more effective control and better clinical outcomes. However, further randomized trials are necessary in order to determine optimal dosing, timing as well as the potential local side effects.

Early detection of complete vascular occlusion in a pedicle flap model using quantitative [corrected] spectral imaging.

Vascular occlusion after tissue transfer is a devastating complication that can lead to complete flap loss. Spatial frequency domain imaging is a new, noncontact, noninvasive, wide-field imaging technology capable of quantifying oxygenated and deoxygenated hemoglobin levels, total hemoglobin, and tissue saturation. Pedicled fasciocutaneous flaps on Wistar rats (400 to 500 g) were created and underwent continuous imaging using spatial frequency domain imaging before and after selective vascular occlusion. Three flap groups (control, selective arterial occlusion, and selective venous occlusion) and a fourth group composed of native skin between the flaps were measured. There were no statistically significant differences between the control flap group and the experimental flap groups before selective vascular occlusion: oxyhemoglobin (p=0.2017), deoxyhemoglobin (p=0.3145), total hemoglobin (p=0.2718), and tissue saturation, (p=0.0777). In the selective arterial occlusion flap group, percentage change in total hemoglobin was statistically different from that of the control flap group (p=0.0218). The remaining parameters were not statistically different from those of the control flap: percentage change in oxyhemoglobin (p=0.0888), percentage change in deoxyhemoglobin (p=0.5198), and percentage change in tissue saturation (p=0.4220). The selective venous occlusion flap group demonstrated changes statistically different compared with the control flap group: percentage change in oxyhemoglobin (p=0.0029) and deoxyhemoglobin, total hemoglobin, and tissue saturation (p<0.0001). Spatial frequency domain imaging provides two-dimensional, spatially resolved maps of tissue oxyhemoglobin, deoxyhemoglobin, total hemoglobin, and tissue saturation. Results presented here indicate that this can be used to quantify and detect physiologic changes that occur after arterial and venous occlusion in a rodent tissue transfer flap model. This portable, noncontact, noninvasive device may have a high clinical applicability in monitoring postoperative patients.

Sildenafil as a protecting drug for warm ischemic kidney transplants: experimental results

Editorial Comment This is an interesting experimental study in pigs, on which the authors tested the intra-arterial injection of reverse thermoplastic polymer LeGoo-XL that allows temporary selective vascular occlusion. The polymer was used with the intend of facilitate hemostasis for laparoscopic partial nephrectomy of the lower (caudal) pole. The perfusion hemostasis was not reliable in achieving occlusion while when using a local plug formation for hemostasis the results were consistent, with occlusion time from 13 to 30 minutes. The authors performed 2 robotic partial nephrectomies and concluded that the technique allowed minimal blood loss. Nevertheless, the authors did not take into account previous studies on intra-renal anatomy in pigs. While the collecting system anatomy is very similar to that of humans (1), the arterial (2) and venous (3) intra-renal anatomy in pigs is different from that of humans in many aspects that would be interesting to be discussed. Also, there are many important differences in the upper and lower pole vascular anatomy, being the upper pole vessels much more complex in distribution. Although we cannot transpose the results to clinical setting, the study opened new avenue to enhance the possibility of partial nephrectomy.

Temporary Segmental Renal Artery Occlusion Using Reverse Phase Polymer for Bloodless Robotic Partial Nephrectomy

Renal vascular clamping with ensuing warm ischemia is typically needed during robotic or laparoscopic partial nephrectomy. We developed a technique for angiographic delivery of the novel intra-arterial reverse thermoplastic polymer LeGoo-XL that allows temporary selective vascular occlusion with normal perfusion of the remaining kidney. Eight pigs underwent a total of 16 selective angiographic occlusions of the lower pole segmental artery using gel polymer. The technical feasibility of 2 hemostatic techniques, perfusion hemostasis and local plug formation, was assessed in 4 pigs each. Selective ischemia time was recorded and the vascular occlusion site was noted radiographically and laparoscopically. The feasibility of reversing the polymer from solid back to liquid state to allow reperfusion was determined. Pathological analysis of the kidney was completed in these acute model pigs. In the last 2 cases lower pole robotic partial nephrectomy was done using the da Vinci surgical system. Selective lower pole ischemia was achieved in all 8 cases. Perfusion hemostasis yielded an inconsistent duration of occlusion (zero to greater than 60 minutes). Vascular occlusion time using local plug formation was more reliable (17 to 30 minutes) with consistent ability to reverse the plug to liquid state by cold saline flush. Two lower pole robotic partial nephrectomies were completed with minimal blood loss. We developed a reliable technique of angiographic delivery of gel polymer for temporary vascular occlusion of selective renal artery branches using local plug formation. Ongoing studies are under way to assess technique consistency and the long-term effects of the polymer.

Anatomische und atypische Resektionen des Gallenblasenbetts beim Gallenblasenkarzinom

At present, atypical as well as anatomic liver resections are recommended as the surgical therapy for gallbladder cancer (GC) at stages > or = T 2. The aim of this study was to compare atypical with anatomic resections (mostly resections of segments IV b / V with selective vascular occlusion using the round ligament approach). Between November 1994 and January 2007, n = 56 patients were treated for GC. The staging, operative and histological results and the postoperative course were recorded. In addition, the survivals at a mean follow-up of 13 (range: 3-54) months were estimated and compared between the two study groups. We performed 28 liver resections for GC (n = 14 atypical and n = 14 anatomic resections). In the anatomic resection group, there was one extended right hepatectomy as well as thirteen segment IV b / V resections. The volume of the resected liver specimen, the frequency of the Pringle manoeuvre, the transfusion requirements, and the duration of the operation did not differ between the two study groups. However, in only 64 % of the atypical resections, the recommended resection margin of at least 3 cm could be achieved. One patient died after extended hepatectomy. There were no other major complications. The mean follow-up was 16 +/- 5 months in the anatomic and 22 +/- 7 months in the atypical resection group. Survival was not statistically different between the two study groups. Segment IV b / V resections are attractive procedures to treat GC due to their lower invasiveness in spite oncological adequacy. However, we could not demonstrate any superiority in terms of survival for the segment IV b / V liver resections. Nevertheless, extended liver resections are rarely necessary in the operative treatment of GC.

The renal sequelae of a novel triphasic approach to blood loss reduction during hepatic resection

Aims To report our novel triphasic approach to minimising blood loss during hepatic resection and the renal sequelae. Methods Fifty consecutive patients (median age 63.3 years, range 37–86) underwent hepatic resection. Triphasic approach consisted of: pre-operative bowel preparation with no supplementary fluids; intraoperative intravenous fluid restriction with low central venous pressure (<5 cmH 2O) and continuous selective occlusion of the left or right portal structures and corresponding hepatic vein/s. The following variables were analysed: blood loss; transfusion requirements; perioperative renal function; perioperative morbidity and mortality. Results Median estimated blood loss was 330 mL (range 50–1200). No patient was transfused intraoperatively, with two patients transfused post-operatively. Median intraoperative urine output prior to hepatic re-perfusion was 28.4 mL/h (range 13.3–40.0) with no patient developing renal impairment. Morbidity occurred in 22% of patients with no documented hepatic failure. There was zero 30-day mortality. Conclusions Pre-operative dehydration and intraoperative fluid restriction combined with continuous selective vascular occlusion minimizes blood loss during hepatic resection with no consequent detriment to renal function.

Effect of photodynamic therapy on the function of the outer blood-retinal barrier in an in vitro model

Photodynamic therapy (PDT) is a well established clinical treatment for age-related macular degeneration (AMD), and comprises intravenous injection of verteporfin and subsequent application of a non-thermal laser beam to the area of AMD to induce selective vascular occlusion. Since there is evidence that PDT may cause outer blood-retinal barrier (BRB) breakdown and possibly RPE cell alteration, we investigated the effect of PDT on the BRB function of the RPE in an in vitro model. Twenty-one monolayers of human RPE cells were cultured on semipermeable membranes until a stable barrier function was achieved as determined by transepithelial electrical resistance (TER) and sodium fluorescein permeability. To test the effect of PDT on the outer BRB function, non-thermal laser (692 nm), verteporfin or a combination of both were applied. TER assessment prior to and after PDT was utilized to identify changes in barrier function of the RPE in this in vitro model. Finally, monolayers of RPE cells were evaluated by transmission electron microscopy (TEM). No significant TER decrease was observed after application of non-thermal laser alone or after administration of verteporfin in therapeutic concentrations, but combination of these modalities resulted in significantly decreased TER within 4 h. Except for intercellular blisters, no damage to the RPE was evident in TEM. Verteporfin added at concentrations higher than therapeutic doses (2 mg/ml) resulted in an immediate decrease in TER and damage to the RPE cells. The combination of a therapeutic concentration of verteporfin and application of non-thermal laser resulted in a morphologically and functionally detectable breakdown of the outer BRB function of the RPE without any damage to the RPE cells themselves in vitro. However, increasing the concentration of verteporfin can result in RPE cell damage.

Bile duct exclusion from selective vascular inflow occlusion in rat liver: Role of ischemic preconditioning and N-acetylcysteine on hepatic reperfusion injury

Aim To study the effects of N-acetylcysteine and ischemic preconditioning on the portal triad clamping compared to arterial and portal clamping alone. Methods Eighty EPM 1-Wistar rats were randomized into two groups, depending on inclusion (Group 1) or not (Group 2) of the bile duct in the hepatic vascular pedicle occlusion. Each group was divided into four subgroups as follows. IR 1: 20 minutes after celiotomy, the pedicle containing vascular elements and bile duct to the left lateral and median liver lobes was occluded for 40 minutes, followed by 30 minutes of reperfusion. IPC 1: after 10 minutes of ischemia and 10 minutes of reperfusion, the ischemic preconditioning period, the rats were submitted to the same procedure described for IR 1 Group. NAC 1: the rats received N-acetylcysteine (150 mg/kg) 15 minutes before 40 minutes of ischemia and 5 minutes before 30 minutes of reperfusion. SHAM 1: The hepatic pedicle for the lateral and median liver lobes was dissected after 20 minutes, the bile duct alone was clamped for 40 minutes, and released for an additional 30 minutes. In the IR 2, IPC 2, and NAC 2 groups, ischemia was achieved with an exclusive vascular occlusion. SHAM 2: dissection and observation for 90 minutes. The blood was sampled for liver enzyme levels. Statistical analysis was done ( P ≤ .05). Results Hepatic IR injury was less severe for animals from the classic portal triad clamping (group 1), with regard to AST (IR 1 Group 766 vs IR 2 Group 1380 U/L) and ALT (IR 1 Group 840 vs IR 2 Group 1576 U/L); IPC, but not NAC administration, was able to protect the liver from IR injury for animals from the classic portal triad clamping group, with regard to AST (IPC 1 Group 421 vs NAC 1 Group 1131 U/L) and ALT (IPC 1 Group 315 vs NAC 1 Group 1085 U/L). Conclusions IPC protects the liver from IR injury; classic portal triad clamping results in a less severe hepatic IR injury when compared to bile duct exclusion.