False-positive "Cavernous Transformation" secondary to lymphatic filling in parenchymal hepatic CO(2) injection for portal vein visualization in TIPS procedures.

PURPOSE: To determine the frequency and potential importance of findings initially interpreted as portal vein occlusion with "cavernous transformation" at transjugular intrahepatic portosystemic shunt (TIPS) placement with hepatic parenchymal CO(2) injection. MATERIALS AND METHODS: One hundred forty-seven patients underwent hepatic parenchymal CO(2) injections in the setting of fine-needle CO(2) TIPS procedures. Hepatic parenchymal CO(2) injections were retrospectively reviewed for findings suggestive of cavernous transformation in which direct portal venography confirmed portal vein patency. Direct portography was performed by injecting CO(2) via the fine needle/guide wire complex or a 5-F catheter in a branch of the intrahepatic portal vein. RESULTS: Hepatic lymphatic vessels mimicked cavernous transformation of the portal vein in 29 of the 147 patients (19.7%). One patient with portal vein occlusion showed profuse lymphatic filling without filling the extrahepatic portal vein. Hepatic parenchymal CO(2) injections safely permitted targeting of the portal vein in all patients. CONCLUSIONS: During fine-needle CO(2) TIPS procedures, what was believed to represent reversed flow of hilar collateral vessels represented hepatic lymphatic vessels. Despite the lack of visualization of the portal vein in nearly one-fifth of patients, targeting of the portal vein was facilitated by the fact the hepatic lymphatic vessels showed a periportal distribution. The high incidence of hepatic lymphatic filling suggestive of cavernous transformation necessitates direct portography or wedged hepatic venography to verify portal vein patency before the procedure is aborted.

Factors predicting survival after transjugular intrahepatic portosystemic shunt creation: 15 years' experience from a single tertiary medical center.

PURPOSE: This retrospective analysis was conducted to identify factors predictive of survival after transjugular intrahepatic portosystemic shunt (TIPS) creation. MATERIALS AND METHODS: Patients who underwent TIPS creation between January 1991 and December 2005 at a tertiary-care center were identified. Log-rank tests were used to compare the cumulative survival functions among groups of patients who underwent TIPS creation for various indications. Thirty-day mortality after TIPS creation was examined by logistic regression. Cox proportional-hazards analyses were performed to analyze the cumulative 90-day and 1-year survival. Selected variables such as creatinine, bilirubin, and International Normalized Ratio (INR) were assessed with respect to survival. RESULTS: The study included 352 patients, of whom 229 (65.1%) were male. The mean age at the time of TIPS creation was 53.6 years (range, 21-82 y). A Model for End-stage Liver Disease (MELD) score greater than 15 was significantly associated with poor survival (P < .05) at 30 days, 90 days, and 1 year after TIPS creation. Independently, a serum total bilirubin level greater than 2.5 mg/dL, an INR greater than 1.4 (P < .05), and a serum creatinine level greater than 1.2 mg/dL were predictive of poor survival. Finally, age greater than 70 years was associated with poor survival at 90 days and 1 year after TIPS creation (P < .05). CONCLUSION: The choice to create a TIPS in individuals whose MELD score is greater than 15 and/or whose age is greater than 70 years should involve a careful consideration of risk/benefit ratio, taking into account the finding that such patients have significantly poorer survival after TIPS creation.

Hepatic artery embolization for control of symptoms, octreotide requirements, and tumor progression in metastatic carcinoid tumors.

Hepatic artery embolization (HAE) has been utilized for treatment of advanced hepatic carcinoid metastases, with promising symptom palliation and tumor control. Our institution employs transcatheter HAE using Lipiodol/Gelfoam for treatment of carcinoid hepatic metastases, and this report presents our experience with twenty-four patients, examining symptom control, quality-of-life, octreotide dependence, and tumor progression. Twenty-four (11 male, 13 female, mean age = 59.4 +/- 2.5 yr) patients with carcinoid and unresectable hepatic metastases, confirmed by urinary 5-hydroxyindole acetic acid (5-HIAA) measurement and biopsy, were treated with Lipiodol/Gelfoam HAE from 1993-2001. Median follow-up was 35.0 months. Before HAE, 14 patients (58.3%) had malignant carcinoid syndrome, with symptoms quantified using our previously reported Carcinoid Symptom Severity Score, and 13 patients (54.2%) required octreotide for symptom palliation. Following treatment, symptom severity, octreotide dose, and tumor response were measured. Asymptomatic patients did not develop symptoms or require following treatment. Hepatic metastases remained stable (n = 4) or decreased (n = 19) in 23 patients (95.8%). Mean pretreatment Symptom Severity Scores (3.8 +/- 0.2), decreased to 1.4 +/- 0.1 post-treatment (P < 0.00001), with 64.3% of patients becoming asymptomatic. Mean pretreatment octreotide dosages (679.6 +/- 73.0 microg/d), decreased to 262.9 +/- 92.7 microg/d (P = 0.0024) post-treatment, with 46.2% of patients discontinuing octreotide. There were no treatment-related serious complications or deaths. This study demonstrates that Lipiodol/Gelfoam HAE produces excellent control of malignant carcinoid syndrome, allowing patients to decrease or eliminate use of octreotide, while controlling hepatic tumor burden.

Carbon dioxide in angiography to reduce the risk of contrast-induced nephropathy.

In the 1970s, Hawkins pioneered the intra-arterial use of carbon dioxide gas for high-risk patients who were allergic to iodinated contrast material and for those with renal failure. With the advent of digital subtraction angiography in 1980, reliable imaging of "low-density" CO(2) contrast agent became available. Subsequently, with the addition of high-resolution of digital subtraction angiography, stacking software (adding multiple images), tilting tables and a reliable, user-friendly delivery system, CO(2) imaging has become nearly comparable to and, in some cases, superior to that of iodinated contrast media. It is the only safe contrast agent for patients in renal failure, which is extremely important in view of the increasing incidence of diabetes and complexities of interventional procedures. The low viscosity of CO(2) not only improves the sensitivities of several diagnostic procedures but may afford advantages for several interventional procedures.

A simple DSA method to detect air contamination during CO2 venous studies.

The use of CO2 as a contrast agent has increased significantly for visualization of the central veins, inferior vena cava, and portal vein. The most serious complication associated with CO2 studies is air contamination. We evaluated a simple digital subtraction angiogram (DSA) method to detect air contamination during CO2 venous studies. After injections of 5, 10, and 20 cm3 of CO2 and 5 cm3 of air into the inferior vena cavas of five domestic swine in the left lateral decubitus position, a DSA was performed using the cross-table lateral projection to visualize the gases trapped in the right atrium. The time to complete dissolution of CO2 at increased doses was compared to that of air. Vital signs were observed during and after CO2 or air injection. In all animals, DSA showed the trapped gas outlining the wall of the right atrium. Five cubic centimeters of CO2 was cleared from the right atrium in an average of 46 sec (21-60 sec), whereas 5 cm3 of air remained visible over 5 min. Ascending doses of CO2 increased the time of dissolution to 54 sec (47-67 sec) for 10 cm3 and 70 sec (45-90 sec) for 45 cm3. Vital signs remained stable during the study. Using DSA, CO2 can be distinguished from air by demonstrating rapid absorption of the former, thus allowing detection of air contamination during CO2 venous studies. If the gases trapped in the right atrium remain visible 90 sec after the injection, air contamination should be suspected.

Potential air contamination during CO2 angiography using a hand-held syringe: theoretical considerations and gas chromatography.

PURPOSE: To assess air contamination in the hand-held syringes currently used for CO2 delivery and to determine whether there is an association between their position and the rate of air contamination. METHODS: Assessment of air contamination in the syringe (20 ml) included theoretical modeling, mathematical calculation, and gas chromatography (GC). The model was used with Fick's first law to calculate the diffusion of CO2 and the amount of air contamination. For GC studies, the syringes were placed in the upright, horizontal, and inverted positions and gas samples were obtained after 5, 10, 20, 30, and 60 min. All trials with each position for each sampling time were performed five times. RESULTS: The amounts of air contamination with time calculated mathematically were 5-10% less than those of GC. With the diffusivity of air-CO2 at 0.1599 cm2/sec (9.594 cm2/min), air contamination was calculated to be 60% at 60 min. With GC air contamination was 13% at 5 min, 31% at 20 min, 43% at 30 min, and 68% at 60 min. There was no difference in air contamination between the different syringe positions. CONCLUSION: Air contamination occurs in hand-held syringes filled with CO2 when they are open to the ambient air. The amounts of air contamination over time are similar among syringes placed in the upright, horizontal, and inverted positions.

Minimizing hemodialysis vascular access trauma with an improved needle design.

The maintenance and longevity of hemodialysis vascular access remains one of the most problematic topics in the care of dialysis patients. Although much attention has focused on neointimal hyperplasia, the repetitive trauma to vessel walls by dialysis needles causes significant cumulative damage that has undergone little investigation. Commercial needles have beveled tips with intentional cutting surfaces to ease insertion. It was hypothesized that a pencil-point conical-shaped needle would cause less damage by taking advantage of the elasticity of native fistulae and produce an improved hole configuration in synthetic materials with minimal ability to stretch. A needle was subsequently designed with a removable pencil-point trocar and a side arm for the dialysis tubing. Once the trocar is removed, the blunt-ended cannula can be advanced or can be subject to inadvertent motion without causing damage to the luminal surface of the access. The new design as well as standard 15-gauge hemodialysis needles were tested on Gore-Tex graft material and two bovine carotid artery preparations. Scanning electron microscopy was used to study the hole patterns. For all materials, the commercial needle holes had typical crescent shapes, and the cuts sliced sequentially through the various layers. For grafts, the new design caused a linear defect parallel to the axis of the graft that may preserve longitudinal strength. Interestingly, that tear line was nearly perpendicular to the linear hole in the thin polytetrafluoroethylene overwrap, which would be consistent with maintenance of hoop integrity. It is believed that these nonoverlapping defects would also improve hemostasis. The bovine specimens tested the importance of tissue stretching : Fresh carotid artery had experimental holes dramatically smaller than those from standard needles. In the denatured tissue, the experimental needle provided less benefit than that observed in fresh tissue, which is likely due to limited elasticity of the preserved artery. Improvement in needle design thus provides distinct advantages for native vessels and unique less traumatic holes in current synthetic materials. Pencil-point needle designs may be particularly applicable to the development of new elastomeric graft material.

CO2 splenoportography: preliminary results.

OBJECTIVE: Previously, splenoportography with 18-gauge needles provided excellent portal imaging. However, because of concern about bleeding, this technique was replaced with arterial portography and noninvasive techniques, which are not always accurate. We present a modification of splenoportography using CO2 and an ultrafine needle in eight patients whose previous imaging studies were inconclusive. CONCLUSION: CO2 splenoportography is safe and expedient and provides adequate visualization of the portal system for surgical planning in selected patients.

Preoperative portal vein embolization for extended hepatectomy.

OBJECTIVE: To examine the authors' experience with preoperative ipsilateral portal vein embolization (PVE) and assess its role in extended hepatectomy. SUMMARY BACKGROUND DATA: Extended hepatectomy (five or more liver segments) has been associated with higher complication rates and increased postoperative liver dysfunction than have standard hepatic resections involving lesser volumes. Recently, PVE has been used in patients who have a predicted (postresection) future liver remnant (FLR) volume less than 25% of total liver volume in an attempt to increase the FLR and reduce complications. METHODS: Sixty patients from 1996 to 2002 were reviewed. Thirty-nine patients had PVE preoperatively. Eight patients who had PVE were not resected either due to the discovery of additional unresectable disease after embolization but before surgery (n = 5) or due to unresectable disease at surgery (n = 3). Therefore, 31 patients who had PVE subsequently underwent extended hepatic lobectomy. A comparable cohort of 21 patients who had an extended hepatectomy without PVE were selected on the basis of demographic, tumor, and liver volume characteristics. Patients had colorectal liver metastases (n = 30), hepatocellular carcinoma (n = 15), Klatskin tumors (n = 9), peripheral cholangiocarcinoma (n = 3), and other tumors (n = 3). The 52 resections performed included 42 extended right hepatectomies, 6 extended left hepatectomies, and 4 right hepatectomies extended to include the middle hepatic vein and the caudate lobe but preserving the majority of segment 4. Concomitant vascular reconstruction of either the inferior vena cava or hepatic veins was performed in five patients. RESULTS: There were no differences between PVE and non-PVE groups in terms of tumor number, tumor size, tumor type, surgical margin status, complexity of operation, or perioperative red cell transfusion requirements. The predicted FLR was similar between PVE and non-PVE groups at presentation. After PVE the FLR was higher than in the non-PVE group. No complications were observed after PVE before resection. There was no difference in postoperative mortality, with one death from liver failure in the non-PVE group and no operative mortality in the PVE group. Postoperative peak bilirubin was higher in the non-PVE than the PVE group, as were postoperative fresh-frozen plasma requirements. Liver failure (defined as the development of encephalopathy, ascites requiring sustained diuretics or paracentesis, or coagulopathy unresponsive to vitamin K requiring fresh-frozen plasma after the first 24 hours postresection) was higher in the non-PVE patients than the PVE patients. The hospital stay was longer in the non-PVE than the PVE group. CONCLUSIONS: Preoperative PVE is a safe and effective method of increasing the remnant liver volume before extended hepatectomy. Increasing the remnant liver volume in patients with estimated postresection volumes of less than 25% appears to reduce postoperative liver dysfunction.