Optimized viewing angles for cardiac electrophysiology ablation procedures.

PURPOSE: Catheter ablation is a common treatment option for atrial fibrillation (AF). Interventional C-arm X-ray systems are used for guiding AF procedures, employing standard view positions. Since the projection angles are not adapted to the individual patient anatomy, standard projections do not necessarily offer the best views of important anatomical structures. Using a pre-procedural 3D data set acquired with MRI or CT, suitable ablation sites (lines) can be identified in advance so an ablation plan can be superimposed on fluoroscopic images to guide the procedure. METHODS: A method was developed to estimate optimized projection views for biplane X-ray C-arm systems based on planning data for AF ablation procedures. The estimated viewing angles were compared to standard angulations using an objective quality metric, the length of the planned ablation line as seen under X-ray. This method was tested using 35 clinical datasets annotated with planned ablation lines for ipsilateral pulmonary vein isolation. RESULTS: The optimized views computed using the new method yielded 28 % less foreshortening of pre-planned ablation lines on average. In one case, anatomy-based view calculation lead to a 69 % reduction in foreshortening. CONCLUSION: The commonly used standard views provide reasonable a priori choices, and some improvement is possible by switching among common angulations depending on the treatment region. Further gains are possible by using anatomy-optimized biplane C-arm angulations.

Curcumin attenuates oxidative stress and inflammatory response in the early phase after partial hepatectomy with simultaneous intraabdominal infection in rats.

BACKGROUND: Curcumin is a nontoxic, hepatoprotective antioxidant. It has been shown to efficiently scavenge oxygen free radicals, increase intracellular glutathione concentrations, and prevent lipid peroxidation in rat hepatocytes. Moreover, it has strong anti-inflammatory effects. In the present study we assessed its effect in a model of liver regeneration impaired by bacterial infections. MATERIAL AND METHODS: Male Sprague-Dawley rats underwent sham operation, cecal ligation and puncture (CLP), synchronous partial hepatectomy (PH), and CLP or synchronous PH+CLP with perioperative application of curcumin (100 mg per kg bodyweight per d) 48 h before surgery. Rats were sacrificed 24 h after surgery. Liver function was analyzed by measuring the serum albumin, serum bilirubin, and bile production. The local inflammatory response in the liver tissue was evaluated by quantification of TNF-alpha, IL-6 mRNA, and quantification of IL-1beta by ELISA. In addition, hepatic concentrations of reduced glutathione (GSH) and the oxidized disulfide dimer of glutathione (GSSG) were measured for determination of the redox state. RESULTS: After simultaneous PH+CLP curcumin significantly reduced the expression of TNF-alpha and IL-6 mRNA in the liver tissue. The IL-1beta concentration in the liver was also slightly, but not significantly, lower in the curcumin group. A severe depletion of hepatic glutathione was found in the PH+CLP group. This was reversed by curcumin application, after which the GSH to GSSG ratio increased markedly. The hepatocellular damage, measured by ALT liberation, was significantly lower in the curcumin treated group. The relative liver weight in the curcumin group was significantly higher 24 h after PH+CLP. However, hepatocellular proliferation parameters were not significantly improved by antioxidative treatment with curcumin. Only the Ki-67 index was slightly higher in the curcumin treated PH+CLP group (14+/-3%) than in the untreated PH+CLP group (7%+/-3%). The hepatocyte density was significantly lower in the curcumin group than in the corresponding untreated group. CONCLUSION: In the present model, curcumin revealed significant hepatoprotective effects with stabilization of redox state, reduced liberation of liver enzymes, and attenuated expression of pro-inflammatory cytokines. However, the hepatocellular proliferation was not significantly influenced.

Effects of protein kinase C activation on cardiac repolarization and arrhythmogenesis in Langendorff-perfused rabbit hearts.

AIMS: Cardiac arrhythmias are still a major cause of mortality in western countries. Currently available antiarrhythmic drugs are limited by a low efficacy and proarrhythmic effects. The role of the protein kinase C (PKC) signalling pathway in arrhythmogenesis is still unclear. The goal of the present study was to test the effects of PKC stimulation on whole heart electrophysiology and its pro-/antiarrhythmic activity. METHODS AND RESULTS: Left ventricular (LV) action potential duration (APD 90%) was determined in 27 Langendorff-perfused rabbit hearts, using Tyrode solution plus the PKC agonist phorbol-12-myristate-13-acetate (PMA; 100 nM) alone (nine rabbits), Verapamil alone (n = 6), or PMA in combination with Verapamil (0.25 mg/L, six rabbits), or bisindolylmaleimide (0.5 microM, n = 6). Intermittent programmed extra-stimulation was performed to induce ventricular arrhythmias. Administration of PMA alone led to a significant shortening of repolarization (APD 90%, 157 +/- 8 vs. 128 +/- 5 ms, P<0.05). Non-sustained ventricular fibrillation (VF) could be induced in seven out of nine animals. After perfusion of Verapamil (156 +/- 6 vs. 169 +/- 4 ms, P>0.05) or bisindolylmaleimide, a selective inhibitor of PKC (136 +/- 4 vs. 146 +/- 4 ms, P>0.05), PMA-induced shortening of repolarization could be inhibited, and induction of VF failed. Verapamil alone did not affect APD and VF could not be induced. CONCLUSIONS: Activation of PKC facilitates induction of VF, which is most likely due to a shortening of repolarization and a prominent calcium influx. These findings demonstrate involvement of the PKC-signalling pathway in arrhythmogenesis.

Magnetic fluid hyperthermia (MFH)reduces prostate cancer growth in the orthotopic Dunning R3327 rat model.

BACKGROUND: Magnetic fluid hyperthermia (MFH) is a new technique for interstitial hyperthermia or thermoablation based on AC magnetic field-induced excitation of biocompatible superparamagnetic nanoparticles. Preliminary studies in the Dunning tumor model of prostate cancer have demonstrated the feasibility of MFH in vivo. To confirm these results and evaluate the potential of MFH as a minimally invasive treatment of prostate cancer we carried out a systematic analysis of the effects of MFH in the orthotopic Dunning R3327 tumor model of the rat. METHODS: Orthotopic tumors were induced by implantation of MatLyLu-cells into the prostates of 48 male Copenhagen rats. Animals were randomly allocated to 4 groups of 12 rats each, including controls. Treatment animals received two MFH treatments following a single intratumoral injection of a magnetic fluid. Treatments were carried out on days 10 and 12 after tumor induction using an AC magnetic field applicator system operating at a frequency of 100 kHz and a variable field strength (0--18 kA/m). On day 20, animals were sacrificed and tumor weights in the treatment and control groups were compared. In addition, tumor growth curves were generated and histological examinations and iron measurements in selected organs were carried out. RESULTS: Maximum intratumoral temperatures of over 70 degrees C could be obtained with MFH at an AC magnetic field strength of 18 kA/m. At a constant field strength of 12.6 kA/m, mean maximal and minimal intratumoral temperatures recorded were 54.8 degrees C (centrally) and 41.2 degrees C (peripherally). MFH led to an inhibition of tumor growth of 44%-51% over controls. Mean iron content in the prostates of treated and untreated (injection of magnetic fluids but no AC magnetic field exposure) animals was 82.5%, whereas only 5.3% of the injected dose was found in the liver, 1.0% in the lung, and 0.5% in the spleen. CONCLUSIONS: MFH led to a significant growth inhibition in this orthotopic model of the aggressive MatLyLu tumor variant. Intratumoral deposition of magnetic fluids was found to be stable, allowing for serial MFH treatments without repeated injection. The optimal treatment schedules and temperatures for MFH need to be defined in further studies.

Evaluation of magnetic fluid hyperthermia in a standard rat model of prostate cancer.

PURPOSE: To examine the feasibility and potential of magnetic fluid hyperthermia (MFH) as a minimally invasive method for hyperthermia treatment of prostate cancer. MATERIALS AND METHODS: Orthotopic Dunning R3327 prostate tumors were induced in 20 male Copenhagen rats. The animals either received MFH treatment following intratumoral administration of magnetic fluids or were used as either tumor growth controls for determination of iron distribution in selected organs or as histologic controls without MFH treatment. The MFH treatments were carried out at 45 degrees C or 50 degrees C using an AC magnetic field applicator system designed for small animals. RESULTS: Sequential treatments with MFH were possible following a single intratumoral injection of magnetic fluid. Intratumoral temperatures of 50 degrees C and more were obtained and were monitored online using fluoro-optic thermometry. Four days after MFH treatments, 79% of the injected dose of ferrites was still present in the prostate. CONCLUSIONS: The successful intraprostatic nanoparticle infiltration and stable steady-state intratumoral treatment temperatures demonstrate the feasibility of MFH in a prostate cancer model. Efficacy and survival benefit must be confirmed in further experiments.