Adequate Venous Outflow Research Articles

Combined en bloc liver–double kidney transplantation in an infant with IVC thrombosis

We report a case of a pediatric en bloc liver-double kidney transplant in a patient with IVC thrombosis below the renal veins. The patient is an 11-month-old girl diagnosed with congenital nephrotic syndrome at two months of age. Multifocal liver masses were identified on routine ultrasound at eight months of age. Alpha fetoprotein level was 55 319. Biopsy confirmed hepatoblastoma. CT scan confirmed multiple lesions in both lobes, which would require liver transplantation for resection. She was also found to have thrombosis of her infrarenal IVC secondary to multiple central lines. She was listed for combined liver-kidney transplant and began chemotherapy. After four cycles of chemotherapy, she underwent bilateral nephrectomies followed by a combined en bloc liver-double kidney transplant from a size matched donor. In order to provide adequate venous outflow from the kidneys in the absence of a recipient infrarenal IVC, the donor liver and kidneys were procured en bloc with a common arterial inflow via the infrarenal aorta and common outflow via the suprahepatic IVC. Kidney transplantation in the absence of adequate recipient venous drainage may require unusual vascular reconstruction techniques. This case demonstrates a novel approach in patients who may require combined liver-kidney transplantation.

Adult Right Lobe Live Donor Liver Transplantation Without Reconstruction of the Middle Hepatic Vein: A Single-Center Study of 109 Cases

We report our experience in adult-to-adult right hepatic lobe living donor liver transplantation (ALDLT) using extension of the hepatectomy transection line medially to incorporate the right middle hepatic vein branches into the donor graft. One hundred and nine ALDLT were performed at the University of Colorado from August 1997 to December 2005. Donors were screened preoperatively for hepatic venous anatomy compatible with this technique. Of the 109 ALDLT, the first 10 did not include the right middle hepatic vein branches in the graft. As such, three patients required retransplantation, two from graft loss because of venous congestion. Of the next 99 transplants, only 11 required retransplantation and none because of venous congestion. This approach allows adequate venous outflow through the right hepatic vein more than 1 cm, which is demonstrated by the absence of graft loss from venous congestion and superior graft survival.

Variation in the venous drainage of left lateral segment liver graft requiring reconstruction of segment III vein with donor iliac artery

Variation in the venous drainage of left lateral segment liver graft requiring reconstruction of segment III vein with donor iliac artery

Impact of hepatic vein deprivation on liver regeneration and function after major hepatectomy

In extended liver resections, the preservation of vascular and biliary structures of the entire remnant liver is of paramount importance. The impact of venous outflow impairment and its consequences for liver regeneration and function are still a matter of debate. Rats (n = 75) were subjected to a 90% partial hepatectomy (PH), to a 70% liver resection with narrowing of the hepatic outflow of an additional 20% parenchyma (70%+ PH) or to an anatomic 70% PH. Postoperatively hepatocyte proliferation (Ki-67), liver function and survival were assessed. Gene expression analysis for markers of regeneration was determined by in-house complementary (DNA) arrays and quantitative real-time polymerase chain reaction (RT-PCR). Ninety percent PH led to a greater regenerative response as shown Ki-67 compared to animals with a 70%+PH (p < 0.05). However, liver function was equally impaired in both groups. Rats with 70% PH showed a greater proliferation index with less hepatic injury and better liver function. While mortality was 0% in the group of 70% PH, rats with 90% PH and 70+PH had a reduced survival of 75% (p < 0.05) Venous outflow obstruction leads to an impairment of liver regeneration and liver function. In cases with critically small liver remnants, restoration of an adequate venous outflow may be mandatory.

Venous outflow reconstruction with surgically reopened obliterated umbilical vein in domino liver transplantation

Venous outflow reconstruction with surgically reopened obliterated umbilical vein in domino liver transplantation

Computer‐Assisted Operative Planning in Adult Living Donor Liver Transplantation: A New Way to Resolve the Dilemma of the Middle Hepatic Vein

An adequate venous outflow is essential for securing viability of both graft and remnant in adult living donor liver transplantation (ALDLT). Seventy-five potential live liver donors were evaluated for LDLT by means of an "all-in-one" CT, which defined the biliary tree, portal vein, hepatic artery, and hepatic vein anatomy. The acquired data sets were further analysed by means of the software HepaVision (MeVis, Germany). Only a minority (29%) of potential donors were found to have a vascular and biliary anatomy consistent with the classically described "normal" patterns. The vast majority (71%) had "anatomical variations". Thirty-nine (52%) donors underwent ALDLT hepatectomy. The right hepatic vein was dominant in 64 cases, representing 48 +/- 6% of the total liver volume (TLV). The middle hepatic vein was dominant in 11 cases, making up 40 +/- 8% of the TLV. The left hepatic vein was never dominant. The volume contribution of the middle hepatic vein (MHV) was 114-782 ml for the right and 87-419 ml for the left hemiliver. Computer-assisted planning allows for the 3D reconstruction of the vascular and biliary anatomy, automatic calculation of the total and territorial liver volumes, and risk analysis of hepatic vein dominance relationships. This comprehensive data acquisition supports preoperative evaluation and provides a high degree of safety for donors and improved outcomes for recipients.

Adequate venous drainage: the most critical factor for a successful free jejunal transfer.

Reconstruction of the cervical esophagus with free jejunum can yield excellent functional results. Flap survival alone, however, does not guarantee satisfying functional outcomes. Critical factors that determine the level of function of the flap include the duration of ischemia and degree of venous congestion. An attempt is made in this study to evaluate the degree that these 2 factors influence outcome and to establish safe methods for avoiding suboptimal functional results. Out of 71 patients that underwent free jejunal transfer for the reconstruction of the cervical esophagus between January 1995 and December 1999, 60 patients with available chart records were included into this study. A retrospective chart review was performed on all 60 patients to evaluate the degree of venous congestion in those patients and the choice of recipient veins and method of anastomosis of those veins (end-to-end versus end-to-side). A more detailed review was performed on the 8 patients that underwent reexploration and detailed history, operative method, ischemia time, choice of recipient vessels, technique of anastomosis, immediate postoperative course, and outcome were determined. Following exploration of the flaps, all flaps survived. Two developed partial necrosis. When smaller veins were used as recipient vessels, the chances of venous congestion were found to be higher than when larger recipient veins were used (chi2 analysis, P <0.02). Method of anastomosis and previous radiotherapy were both found to be significant determinants of venous congestion (chi2 P <0.05 for both). Venous problems accounted for 87.5% (7/8) of all reexplorations. In 75% (6/8) of the reexplored patients, pharyngocutaneous fistula formation or stricture formation was noted.The degree of venous congestion and previous radiotherapy are factors that influence the functional outcome of free jejunal flaps. Proper selection of the recipient veins is a critical factor in providing adequate venous outflow and minimizing venous congestion. End-to-side anastomosis to large vessels is a more reliable method that was found to have a significant influence on minimizing venous congestion and is a useful method for the salvage of venous congested flaps.

Significance of venous anastomosis in fingertip replantation.

Adequate venous outflow is the most important factor for successful fingertip replantation. The authors have attempted venous anastomosis in all cases of fingertip replantation to overcome postoperative congestion. In this article, the significance of venous repair for fingertip replantation is described from the authors' results of 64 complete fingertip amputations in 55 consecutive patients, which were replanted from January of 1996 to June of 2001. The overall survival rate was 86 percent. Of the 44 replantations in zone I, 37 survived, and the success rate was 84 percent. Of the 20 replantations in zone II, 18 survived, and the success rate was 90 percent. Venous anastomosis was attempted in all cases, but it was possible in 39 zone I and in all zone II replantations. For arterial repair, vein grafts were necessary in 17 of the 44 zone I and in one of the 20 zone II replantations; for venous repair, they were necessary in six zone I replantations and one zone II replantation. Postoperative vascular complications occurred in 15 replantations. There were five cases of arterial thrombosis and 10 cases of venous congestion. Venous congestion occurred in nine zone I and one zone II replantations. In five of these 10 replantations, venous anastomosis was not possible. In another five replantations, venous outflow was established at the time of surgery, but occlusion occurred subsequently. Except for the five failures resulting from arterial thrombosis, successful venous repair was possible in 49 of 59 replantations (83 percent). Despite the demand for skillful microsurgical technique and longer operation time, the authors' results using venous anastomosis in successful fingertip replantations are encouraging. By performing venous anastomosis, external bleeding can be avoided and a higher survival rate can be achieved. Venous anastomosis for fingertip replantation is a reliable and worthwhile procedure.

Approach to patients with "complex" hemodialysis access problems.

The approach to patients with "complex" permanent hemodialysis (HD) access problems remains poorly defined. The purpose of this review is to outline our current algorithm for patients presenting for dialysis access and to address the management of specific problems that complicate this objective of establishing permanent access. The key components of the algorithm include noninvasive imaging in the diagnostic vascular laboratory to determine all the possible access configurations and invasive imaging with both venography and arteriography to confirm the optimal choice. The specific access-related problems addressed include inadequate ipsilateral vein, inadequate arterial inflow, central vein stenosis/occlusion, multiple previous access failures, and obesity. Despite the label of "complex" access problems, it is possible to construct native arteriovenous fistulas (AVFs) in almost all patients presenting for access using the standard principles of vascular surgery that are based on establishing adequate arterial inflow, adequate venous outflow, and selecting an appropriate conduit.

Extended rat-ear flap model: a new rodent model for studying the effects of vessel supercharging on flap viability.

A new extended rat-ear flap model, with both an axial and a random component, is described. The flap is based on an axial supply by the posterior auricular artery and the posterior facial vein. The random portion, consisting of the rat dorsum, is capable of being supercharged at two separate sites-in the scapular and pelvic regions. There are several advantages to this composite flap. It is a combined axial and random flap. When used as a free flap, the viability of the axial portion serves as an indicator for anastomotic patency. The random portion allows for the investigation of the effects of pharmaceutical manipulation or surgical intervention, e.g., flap supercharging. The results indicate that the axial supply alone can cover approximately 50 percent of the extended rat-ear flap. Moreover, adding supercharging perforators to the random portion significantly increases the area of flap survival. Of interest, an axial vascular supply, coupled with more distal dorsal perforators (pelvic) than proximal (scapular) perforators, may increase survival for the so-called "watershed" area in the middle of the random portion of the flap. Additionally, this study also investigated the relative importance of arterial supply vs. venous drainage, using the extended rat-ear flap model. The flap was either supercharged with both the perforators of the scapular and pelvic arteries, or both scapular and pelvic veins. The results of the study suggests that augmenting venous drainage provides statistically significant improvement (87 percent vs. 51.6 percent) in increasing flap survival, when compared to augmenting the arterial supply. Arterial supercharging provided no improvement in flap survival, when compared to no supercharging (axial vessels + arterial supercharging, 51.6 percent vs. axial vessels alone, 49.9 percent). The results also suggest that providing adequate venous outflow is more important than providing additional arterial blood, and that impaired venous outflow may contribute to some cases of flap failure. However, it should be kept in mind that the best flap survival occurs with both arterial and and venous supercharging.

Stenting of a Venous Stenosis in Vein of Galen Aneurysmal Malformation

The vein of Galen aneurysmal malformation (VGAM) is a high flow arteriovenous shunt at the choroidal level. In the neonatal period, it typically presents with cardiac failure. Venous stenoses, occlusions and anomalies are often present. In the absence of adequate venous outflow pathways, severe, irreversible cerebral parenchymal damage may occur due to intracranial venous hypertension, altered hydrodynamics and ischaemia. We present a case of deployment of a stent across a focal superior jugular bulb stenosis in an effort to avert this outcome.

Venous valves in the neck: implications for microvascular free flap reconstruction.

Successful microvascular free flap reconstruction requires adequate arterial inflow and venous outflow. We report 4 cases that demonstrate the not uncommon occurrence of locating valves in veins during microvascular head and neck reconstructive procedures. Failure to recognize these valves could have compromised the venous anastomosis. The anatomical literature states that veins in the head and neck lack valves, allowing bidirectional blood flow. As a result, there is potential significant flexibility in the selection of recipient veins for the microvascular anastomosis during free flap reconstruction. The unrecognized presence of a venous valve, however, could cause thrombosis of the venous anastomosis and, ultimately, flap failure. This report of venous valves should speak caution to the head and neck microvascular surgeon when he or she is selecting recipient veins in the neck.

The importance of preoperative evaluation of the subclavian vein in dialysis access planning.

Adequate venous outflow is critical to the proper function of a vascular-access graft (arteriovenous fistula) used for chronic hemodialysis. Stenosis of the subclavian vein can significantly compromise this venous outflow. The development of such subclavian vein stenoses has been associated with the prior placement of temporary subclavian vein dialysis catheters. We evaluated the importance of preoperative detection of these stenoses before placement of a permanent vascular-access graft in the upper extremity. Upper extremity venography was performed before placement of a permanent vascular-access graft in 43 patients. A total of 62 extremities were evaluated. A 40% prevalence of moderate or severe subclavian vein stenosis was found in patients with prior or existing temporary dialysis catheters in the subclavian vein. No stenoses were found in patients without a history of dialysis catheters in the subclavian vein. This difference in the prevalence of subclavian vein stenosis is statistically significant (p less than .001). In no case was the stenosis suspected clinically. Before placement of a permanent vascular-access graft, the subclavian vein should be evaluated in all patients with a history of a temporary dialysis catheter in the subclavian vein. The use of sites other than the subclavian vein for temporary dialysis is strongly encouraged.

Selective hepatic venography in primary liver cell carcinoma

With apparent inoperable hepatic cell carcinoma, knowledge of adequate venous outflow from tumor-free liver tissue permits extensive resection with long survival.

Technik der Kanülierung des Confluens sinuum beim Kaninchen für Versuche mit partiellem extrakorporellem Kreislauf

Since an adequate venous blood outflow from the internal jugular vein is not available in the rabbit, a method for venous blood outflow from the Confluens sinuum was developed. It appeared to be useful in experiments with partial extracorporal circulation and for partial oxygenation of the blood circulation during haemodialysis.