CT-guided hook-wire localisation prior to video-assisted thoracoscopic surgery of pulmonary lesions.

AIM: To assess the feasibility, safety, and efficacy of computed tomography (CT)-guided pulmonary nodule localisation using a hooked guide wire before video-assisted thoracoscopic surgery (VATS). MATERIALS AND METHODS: The study included 79 patients with a history of malignancies outside the lung associated with pulmonary nodules. Mean lesion size was 0.7 cm (range 0.5-1.8 cm) and the mean lesion distance to the pleural surface was 1.5 cm (range 0.2-5 cm). All lesions (n=82) were marked with a 22-G hook wire. The technique was designed to insert the tip of the hook wire within or maximally 1 cm from the edge of the lesion. The Mann-Whitney U-test was used for univariate analyses and Fisher's exact test for categorical values. RESULTS: The hooked guide wire was positioned successfully in all 82 pulmonary nodules within mean time of 9 minutes (8-20 minutes, SD: 2.5 minutes). The procedure time was inversely proportional to the size of the lesion (Spearman correlation factor 0.7). Minimal pneumothoraces were observed in five patients (7.6%). Pneumothorax was not correlated to the histopathology of the pulmonary nodules (p>0.09). Focal perilesional pulmonary haemorrhage developed in four patients (5%). Both haemorrhage and pneumothorax were significantly correlated to lesions <10 mm (p=0.02 and 0.01 respectively). The volume of resected lung tissue was significantly correlated to lesions of increased distance from the pleural surface ≥2.5 cm in comparison to lesions of <2.5 cm from the pleural surface. CONCLUSION: CT-guided pulmonary nodule localisation prior to VATS could enable safe, accurate surgical guidance for the localisation of small pulmonary nodules.

Spherical dilatation of the apex in failing left ventricles: a target for surgical remodelling techniques.

AIM: The present study investigates the geometry of failing left ventricles with a special focus on apical deformation. A new surgical remodelling technique is evaluated. METHODS: In 124 patients with impaired left ventricular function (EF<40%) undergoing coronary artery bypass grafting (CABG) left ventricular (LV) geometry was evaluated by MRI scanning before and after surgery. Besides the sphericity index (SI) two further indices were calculated, longitudinal EF (LEF) and an apical conicity index (ACI). The results were compared to 15 patients with coronary heart disease and normal LV function and 10 test persons. In 35 patients with impaired LV function perpendicular apical compression (AC) stitches were placed. RESULTS: In failing left ventricles indexed LV length increased (5.3 ± 0.6 cm/m2 vs. 4.7 ± 0.8 cm/m2 in control patients and 4.6 ± 0.3 cm/m2 in test persons, P=0.03). LEF was reduced (6% ± 4 versus 22% ± 6 and 19% ± 7 P=0.04). The classical SI was 0.56 ± 0.06 in heart failure patients, 0.50 ± 0.05 in control patients and 0.48 ± 0.04 in test persons. The ACI were 0.75 ± 0.06, 0.58 ± 0.06 and 0.57 ± 0.04 respectively (P<0.05), indicating a pronounced dilatation at the apex. After apical compression LEF improved to 15 ± 1%, the ACI to 0.64 ± 0.04 (P=0.04). LVEDV (166 ± 11 mL [AC] vs. 196 ± 14 mL [without AC]) as well as LV-EF (48 ± 3% [AC] vs. 36 ± 2% [without AC]) significantly improved only after remodelling (P<0.05). CONCLUSION: Apical compression improved ventricular geometry and ventricular function in patients with dialatation of the left ventricular apex.

SIMONA 1.0: an efficient and versatile framework for stochastic simulations of molecular and nanoscale systems.

Molecular simulation methods have increasingly contributed to our understanding of molecular and nanoscale systems. However, the family of Monte Carlo techniques has taken a backseat to molecular dynamics based methods, which is also reflected in the number of available simulation packages. Here, we report the development of a generic, versatile simulation package for stochastic simulations and demonstrate its application to protein conformational change, protein-protein association, small-molecule protein docking, and simulation of the growth of nanoscale clusters of organic molecules. Simulation of molecular and nanoscale systems (SIMONA) is easy to use for standard simulations via a graphical user interface and highly parallel both via MPI and the use of graphical processors. It is also extendable to many additional simulations types. Being freely available to academic users, we hope it will enable a large community of researchers in the life- and materials-sciences to use and extend SIMONA in the future. SIMONA is available for download under http://int.kit.edu/nanosim/simona.

Impact of valve calcification on systolic and diastolic valvular function--an in vitro model.

AIM: Despite continuous development of anticalcification treatment for bioprosthetic valves, calcification remains one major cause of structural failure. The aim of this study is to investigate changes in hemodynamic performance and leaflet kinematics in progressively calcified pericardial and porcine aortic valve prostheses. METHODS: Five pericardial (Edwards Perimount Magna) and 5 porcine (Medtronic Mosaic Ultra) aortic valve prostheses (Ø23 mm) were exposed to a high concentration Calcium-phosphate fluid in an in vitro pulse duplicator (300 cycles/minute) for 6 weeks. The prostheses were removed weekly and tested in an artificial circulation system (70 beats/min, Cardiac Output 5 l/min). All prostheses underwent X-ray, computed tomography (CT)-Scan and photographic examination for evaluation of progressive calcification. Leaflet kinematics were visualized with a high-speed camera. RESULTS: Pericardial valves demonstrated faster degeneration with significantly larger radiographic areas of leaflet calcification (16.5+/-4.3% versus 5.6%+/-2.0%) and also significantly higher Ca-uptake (170+/-71 microg/mg versus 103+/-49 microg/mg) after 6 weeks. Despite degeneration systolic function remained superior for pericardial valves (mean effective orifice area [EOA] 1.52+/-0.05 versus 1.28+/-0.11 cm2, P<0.01), but leaflet kinematics showed longer closing times (135+/-11 msec versus 85+/-9 msec after 6 weeks) accompanied by higher regurgitant flow (7.8+/-1.12 mL versus 1.2+/-0.28 mL, P<0.001). CONCLUSION: In vitro pericardial valves calcified faster and more severe than porcine valves leading to impaired diastolic function with prolongation of closing times and higher closing volume. Systolic function remained almost undisturbed by the calcification process. As a consequence in clinical settings, follow-up examinations for structural valve deterioration in porcine valves should focus on systolic performance, in pericardial valves on diastolic function.

Leukocyte depletion during cardiac surgery with extracorporeal circulation in high risk patients.

BACKGROUND: Cardiopulmonary bypass is associated with systemic inflammation that may contribute to increased perioperative mortality. Depletion of circulating leukocytes may reduce the inflammatory response. We studied the effect of a leukocyte depleting filter on leukocyte activation during cardiopulmonary bypass in high risk patients. METHODS: Fifty patients undergoing coronary artery bypass grafting with a preoperative high risk were randomly placed in an arterial line leukocyte filter group (n = 25) with a leukocyte depleting filter. Blood sampling took place from the arterial line to analyze polymorphnuclear elastase and myeloperoxidase at six time points, including: A) before the induction of anesthesia, B) before the induction of the cardiopulmonary bypass C) 1 min after the release of the aorta clamp, D) the end of the operation, E) 1 h postoperative, and F) 24 h postoperative. RESULTS: Levels of polymorphonuclear elastase, (PMNE), and myeloperoxidase (MPO) were found to be higher after the release of the aortic cross clamp in the leukocyte filter group; these levels remained elevated until 24 hours after surgery and were high in comparison to preoperative baseline levels. The differences in PMNE between both groups at time points C and D (p < 0.005) and E (p < 0.05) were statistically significant. The serum levels of the S-100B and neuron specific enolase (NSE) were found to be elevated between time points C and E in both groups without statistical significance. The in-hospital mortality was 16% (4 patients) in leukocyte filter group and 4% in control group (1 patient). CONCLUSIONS: Interestingly, the activation of neutrophils was more pronounced in the LF group. The use of a leucocyte depleting filter was not advantageous for this patient cohort for clinical or biomedical endpoints.

Impact of different pacing modes on left ventricular function following cardiopulmonary bypass.

BACKGROUND: Patients with severely impaired left ventricular (LV) function often demonstrate prolonged inter- and intraventricular conduction. This prospective study investigates hemodynamic effects and outcomes of perioperative temporary biventricular pacing in patients with heart failure undergoing heart surgery. METHODS: 80 consecutive cardiac surgery patients with a LV ejection fraction below 35 % received biventricular stimulation via temporary myocardial electrodes. Group 1 consisted of 40 patients with LV dilatation (mean LVEDD 65 +/- 5 mm), Group 2 of 40 patients with normal or slightly dilated LV (mean LVEDD 52 +/- 4 mm). RESULTS: Hemodynamic parameters were measured immediately, 6 and 24 hours after operation. An increase of cardiac index (CI) and arterial blood pressure with biventricular pacing was observed in 27 patients (Group 1/67.5 %) versus 22 patients (Group 2/55 %) from 2.4 +/- 0.7 l/min/m2 to 3.5 +/- 0.5 l/min/m2 ( P < 0.01). This benefit persisted 6 and 24 hours postoperatively. The remaining patients already showed a higher cardiac index prior to pacing (3.7 +/- 0.9 l/min/m2). In Group 1, the duration of ventilation support and time in the intensive care unit of responding patients was shorter. QRS duration before surgery was not predictive for the response to biventricular pacing. CONCLUSIONS: In the majority of patients with reduced LV function, temporary biventricular pacing improves CO and arterial blood pressure after surgery, especially when LV dilatation is present.

Hemodynamic effects of left ventricular pacing site in an animal model of heart failure.

BACKGROUND: This study investigates how different left ventricular epicardial and endocardial pacing sites influence hemodynamic performance in an animal model of heart failure (HF). METHODS: In six adult sheep, dilated HF was induced by rapid pacing. Subsequently, endocardial left ventricular stimulation was performed using a 64-electrode basket catheter. Epicardial pacing was achieved with temporary electrodes. RESULTS: Baseline cardiac output (CO) was 2.7 +/- 0.4 l/min and improved significantly with lateral wall epicardial and endocardial stimulation (3.6 +/- 0.7 and 3.8 +/- 0.65 l/min), whereas right ventricular pacing led to lower CO (2.1 +/- 0.5 and 2.0 +/- 0.9 l/min). In the optimal pacing location arterial pressure, pulmonary capillary wedge pressure (pcwp) and LV diameters improved significantly. Right ventricular pacing impaired hemodynamics, while no change was observed in the LV inferior wall and apex pacing. CONCLUSION: Endocardial and epicardial pacing of the lateral wall led to an improvement in LV function while right ventricular pacing induced a further reduction of LV performance. As this optimal pacing site cannot always be reached via the coronary sinus, surgical implantation of epicardial electrodes should be considered in all non-responding patients.

External stenting with a new polyester mesh reduces neointimal hyperplasia of vein grafts in a sheep model.

OBJECTIVE: External stents placed around vein grafts have demonstrated effectiveness in reducing neointimal hyperplasia by preventing distension of the thin-walled vein grafts when exposed to arterial pressure. However, the ideal stent material has yet to be defined. The following study investigates the short- and long-term effects of an innovative polyester mesh stent designed with optimized adaptation of circumferential compliance. METHODS: Following in vitro definition of the ideal macro-porous polyester stent material, a total of 12 sheep underwent implantation of bilateral carotid artery vein graft bypasses. In six sheep, the short term outcome (four weeks of implantation) was investigated by comparing the newly-designed stent to native veins, micro-porous PTFE stent grafts and metallic Biocompound stents (BCGs). Flow volume and graft diameter were measured prior to explantation. Grafts were evaluated histologically with respect to morphometry and immunoassaying. In the long-term group (6-month implantation time), the polyester stent was compared to native veins. RESULTS: All stents effectively prevented dilatation of the graft. Perfused vessel diameters of the polyester veins were 8.3+/-0.6 mm. BCG as well as PTFE veins showed diameter reduction to 7.4+/-0.7 mm (p<0.05) and 7.8+/-0.4 mm (p<0.05), respectively. Both in the short and long terms, the new polyester stent led to significantly higher reduction of neointimal hyperplasia and luminal encroachment compared to the native vessel. It proved superior to PTFE stenting, while the Biocompound material failed to prove efficacy. CONCLUSIONS: It was demonstrated that the new macro-porous polyester mesh stent reduced neointimal hyperplasia more effectively than other commercially available stents.

Perioperative elastase activity in cardiac surgery and its role in endothelial leakage.

OBJECTIVE AND DESIGN: The functional activity and pathophysiological effects of polymorphonuclear elastase (PMNE) in cardiac surgery patients are unknown. This in vitro study was done to evaluate whether PMNE activity in patient blood samples may be correlated with decreased endothelial wall integrity. METHODS AND SUBJECTS: PMNE was serially analyzed by PMNE activity in plasma samples from 40 high risk cardiac surgery patients. Endothelial cell cultures were used to study the influence of patient serum on the intercellular integrity. RESULTS: Ex vivo, samples with high PMNE activity (>1.0 mg/ ml), found in 14 patients (35%), neither induced hyperpermeability in cultured endothelial cells nor resulted in intracellular redistribution of the junction molecules cadherin-5 or beta-catenin. However, pretreatment of endothelial cells with these samples but not with low activity (<0.5 mg/ml) samples augmented neutrophil transendothelial migration (>20-fold) in conjunction with formation of intercellular gaps and irregular membrane-associated beta-catenin staining. Neutrophil transmigration was inhibited by blocking neutrophil beta1 integrin but not by the proteinase inhibitor methoxysuccinyl-Ala-Ala-Pro-Ala. CONCLUSIONS: Augmented PMNE activity in cardiac surgery patients does not directly induce endothelial leakage but may indirectly promote neutrophil extravasation and thus perioperative endothelial hyperpermeability.

Performance of stentless versus stented aortic valve bioprostheses in the elderly patient: a prospective randomized trial.

OBJECTIVES: Although stentless aortic bioprostheses are believed to offer improved outcomes, benefits remain unsubstantiated. The aim of our study was to compare stentless with stented bioprostheses, with regard to postoperative changes in left ventricular mass and hemodynamic performance, in the elderly patient. METHODS: Forty patients with aortic stenoses, over the age of 75 years, were randomized to receive either the stented Perimount (n=20) or the stentless Prima Plus (n=20) bioprosthesis. Left ventricular mass regression, effective orifice area, ejection fraction and mean gradients were evaluated at discharge, 6 months and 1 year after surgery. RESULTS: Overall a significant decrease in left ventricular mass was found 1 year postoperatively. However, there was no significant difference in the rate of left ventricular mass regression between the groups. Furthermore, 1 year postoperatively, the hemodynamic performance of the valves and the change in the ejection fraction did not differ between the groups. CONCLUSIONS: Our study shows that in a randomized cohort of elderly patients with aortic stenosis, we were not able to detect significant differences, with regard to hemodynamic performance and regression of left ventricular mass, between the stentless and stented valve groups. To our surprise, previously reported findings of non-randomized trials that showed faster and more complete regression of left ventricular mass and hemodynamic benefits of stentless valves were not reproducible.

Computer-enhanced telemanipulation enables a variety of totally endoscopic cardiac procedures.

BACKGROUND: Since its introduction in the field of cardiac surgery in 1997, computer-enhanced telemanipulation has been used in a number of different specialized areas. In cardiac surgery, various procedures have been successfully completed in totally endoscopic fashion ever since. Between June 1999 and January 2002, 75 closed-chest cardiac procedures have been performed at our institution using the da Vinci telemanipulation system. PATIENTS AND METHODS: In 42 patients, a single-vessel totally endoscopic coronary artery bypass was performed on the arrested heart (left internal thoracic artery (LITA) to left anterior descending artery (LAD), n = 36; right internal thoracic artery (RITA) to right coronary artery (RCA), n = 6). 12 patients had different types of multivessel revascularization using both internal thoracic arteries. 8 patients underwent LITA-to-LAD grafting on the beating heart. 10 patients underwent closure of an atrial septal defect (9 direct, 1 patch). 3 patients received an epicardial left ventricular pacemaker lead, 2 of which were reoperations. RESULTS: Overall conversion rate to any kind of incision was 25 %. The last 26 LITA to LAD patients on the arrested heart had a conversion rate of 4 %. There were no mortalities, 3 patients required reexploration via a median sternotomy, and one patient suffered a hypoxemic brain damage. The first 22 TECAB patients demonstrated excellent graft patency in angiographic control upon discharge. None of the atrial septal defect (ASD) closures showed any residual shunt on the intraoperative transesophageal echocardiogram (TEE). Patients with end-stage heart failure had successful biventricular stimulation. CONCLUSION: Our current experience confirms the feasibility of various totally endoscopic cardiac procedures with good clinical outcomes. After a steep learning curve, the conversion rate could be lowered to an acceptable figure. Some of these procedures at our institution became a reasonable treatment alternative in selected patients.

Biventricular pacing for successful weaning from extracorporal circulation in an infant with complex tetralogy of fallot.

Biventricular pacing therapy is an innovative therapy for improving cardiac output in adult patients with severe heart failure. However, this technique is not yet used in infants with congenital heart disease. We present a six month old infant with tetralogy of fallot and atresia of the left pulmonary artery in which biventricular stimulation led to improved left ventricular function and successful weaning from extracorporeal circulation.

Leukocyte filtration fails to limit functional neutrophil activity during cardiac surgery.

OBJECTIVE AND DESIGN: The beneficial effects of leukocyte filtration on the outcome of cardiac surgery with cardiopulmonary bypass (CPB) is probably due to the limitation of pathogenesis mediated by over-stimulated neutrophils. However, the influence of leukocyte filtration on the functional neutrophil activity has not been studied in detail. Therefore, by using different filtration timing strategies we determined neutrophil effector functions before and after the filter passage as well as blood surrogate markers for neutrophil activation. METHODS: We randomly assigned 80 cardiac surgery patients to four groups (n = 20 each) without (1) and with three different filtration timing strategies (II-IV). As functional end points neutrophil phagocytic activity and oxidative burst upon ex vivo stimulation with E.coli were analyzed from blood of 31 patients whereas polymorphonuclear elastase (PMNE), myeloperoxidase, and malondialdehyde (MDA), a marker for lipid peroxidation was determined in plasma samples from 80 patients. Blood was harvested immediately before and behind the filter (Pall LG6) at different times during CPB. RESULTS: We found that none of the filtration strategies either reduced the number of neutrophils capable of eliciting phagocytic activity and oxidative burst or the activity per cell. In contrast, PMNE and MPO levels in peripheral venous blood were found to be significantly increased in groups II-IV compared with group I throughout the entire filtration period in all patients. MDA was not enhanced in the filter groups. CONCLUSIONS: Our results show that the leukocyte depletion filter in the arterial line of the heart-lung machine failed to limit neutrophil stimulation but rather augmented PMNE plasma levels. We speculate that augmented PMNE and MPO levels mainly stem from neutrophils that are captured within the mesh of the leukocyte filter.

Tilting disc versus bileaflet aortic valve substitutes: intraoperative and postoperative hemodynamic performance in humans.

BACKGROUND AND AIM OF THE STUDY: Due to an asymmetrical/eccentric flow profile at the level of the aortic valve, there is an optimal orientation for each aortic valve design. This study evaluates intraoperative flow dynamics (turbulence and pressure gradient) and follow up results (pressure gradient and left ventricular mass regression) for Medtronic Hall tilting disc (MH) and St. Jude Medical bileaflet (SJM) valves, with both valves in their optimum orientation as defined in previous animal experiments. METHODS: In a randomized prospective study, MH and SJM valves (size > or = 23 mm) were implanted in their optimum orientation in 24 patients with aortic stenosis. Turbulence measurements were performed intraoperatively via a perivascular ultrasound transducer; Reynold's normal stress (RNS) values were calculated as key markers for turbulent stresses. Transvalvular pressure gradients, interventricular septum and posterior wall thickness were measured by transesophageal echocardiography intraoperatively and six months postoperatively. RESULTS: Mean valve size was 23.8 mm in both groups. Intraoperative RNS values (MH 7.5 +/- 2.2 N/m2 versus SJM 9.8 +/- 2.3 N/m2) and pressure gradients (MH 10.0 +/- 2.6 mmHg versus SJM 20.0 +/- 3.4 mmHg) were significantly lower for the tilting disc valve. At six months follow up, pressure gradients were reduced by half for both valves (MH 5.3 +/- 1.7 mmHg; SJM 10.4 +/- 2.3 mmHg), with the difference between the valves being maintained. Left ventricular mass regression was accelerated for MH patients with regard to interventricular septum thickness. CONCLUSION: Our results indicate that the tilting disc mechanism shows superior hemodynamic performance with respect to turbulence and transvalvular pressure gradients compared with the bileaflet mechanism when both valves are implanted in their optimum orientation. This led to significant acceleration of interventricular septum mass regression. The superiority of the tilting disc mechanism is more pronounced in the smaller-sized valves.

Downstream turbulence and high intensity transient signals (HITS) following aortic valve replacement with Medtronic Hall or St. Jude Medical valve substitutes.

OBJECTIVE: High intensity transient signals (HITS) representing microembolization to the brain have been found to contribute to cognitive impairment and psychoneurological dysfunction in patients carrying a mechanical aortic valve. It is unknown, whether HITS represent gaseous or solid emboli. This animal study evaluates the impact of valve orientation on HITS for two different mechanical valves with both valves implanted in their best and worst orientation, which has been defined in previous studies with respect to downstream turbulence. METHODS: In four pigs a rotation device carrying either a Medtronic Hall (MH) or St. Jude Medical (SJM) valve size 23 mm was implanted. The device allowed rotation of the implanted valves without reopening of the aorta. Approximately 30 min after weaning from extracorporeal circulation, a Doppler probe was placed on both common carotid arteries. In different orientations of the implanted valves (best and worst position), HITS were detected by the Doppler probe and recorded for ten min by a transcranial Doppler sonography device (Medilab Inc., Estenfeld, Germany). RESULTS: HITS showed significant change with rotation for both valve designs. With the major orifice of the MH oriented towards the non-coronary leaflet (optimum position) very low HITS-counts (0.8-1.7/min) were observed. In the worst orientation HITS rose to 43-66/min. For the SJM the HITS count in the optimum position was 23.4-24/min and in the worst orientation 38-48/min. CONCLUSIONS: Valve orientation has an important impact on microembolization to the brain. In the optimum orientation (large orifice facing the non-coronary leaflet) the Medtronic Hall valve showed negligible incidence of HITS. The St. Jude Medical bileaflet valve showed less variation but demonstrated significant HITS counts at any orientation. As the MH in the worst position shows significantly higher turbulent stresses than the SJM but no higher incidence of HITS, a strong correlation between turbulence and HITS was not demonstrated by this study.

High-intensity transient signals (HITS) as a parameter for optimum orientation of mechanical aortic valves.

BACKGROUND: In previous studies [1,2], the impact of valve orientation on the hemodynamic performance of mechanical aortic valves has been demonstrated. This study investigates Turbulence (RNS values) and High Intensity Transient Signals (HITS) as a new and objective parameter for hemodynamics in different orientations of Medtronic Hall (MH) and St. Jude Medical (SJM) aortic valves. METHODS: A rotation device carrying MH or SJM valves was implanted in 4 pigs. The device allowed valve rotation without reopening the aorta. In different orientations, turbulent shear stresses (RNS values) and HITS were measured. RESULTS: RNS and HITS changed for both valve designs in various orientations, with superior results for the MH in the hemodynamically best orientation. Downstream turbulence (RNS) and HITS varied into the same direction, but a one-to-one correlation was not observed. CONCLUSIONS: RNS and HITS vary with respect to valve orientation and design with superior results for the tilting disc valve. Both MH and SJM valves showed lower turbulence and HITS counts in their hemodynamically best orientations. HITS were related to downstream turbulence and the hemodynamic performance of the mechanical aortic valves.

Orientation of tilting disc and bileaflet aortic valve substitutes for optimal hemodynamics.

Procedures for implantation of mechanical aortic valves have to consider eccentric flow in the aortic root. We describe how to optimize orientation of tilting disc (Medtronic Hall) and bileaflet (St. Jude Medical) valves. In tilting disc valves, an asymmetric design faces an asymmetric flow. Hemodynamic performance of this valve type, regarding turbulence and pressure gradients, is close to normal physiology and superior to the bileaflet valve design. This difference is more pronounced the smaller the valve size.

Multicenter results of TADpole heart wire system used to treat postoperative atrial fibrillation.

OBJECTIVE: Postoperative atrial fibrillation (AF) affects 20-30% of patients undergoing open-heart surgery, delays mobilization and impairs hemodynamics. Implantation of TADpole Heart Wires offers a new method of applying internal low-energy-shocks to terminate AF. The safety and efficacy of the TADpole system to treat postoperative AF was evaluated in this multicenter trial. METHODS: Two atrial wires, configured with a highly flexible 11.5 cm distal shocking and a 0.5 cm proximal pacing electrode were sutured onto the right and left atrium. Upon detection of AF, R-wave synchronized low-energy-shocks were administered via an energy attenuating External Defibrillator Interface Module or ICD programmer. RESULTS: A total of 296 patients (65+/-9.2 years, 74.7% male) have been enrolled to date in six European centers. The wire placement time was 4.2+/-2.2 min, 65 patients had a total of 83 episodes of AF treated by the TADpole Heart Wire system with a conversion rate of 88.5% (approximate energy of 6+/-2 J), early recurrence of AF was observed in ten patients (12.8%). No clinical complications were reported. The shocks were well tolerated with slight sedation. The ease of withdrawal was 2.3+/-1.2 on a graded scale of 0 (easy) to 10 (difficult). CONCLUSIONS: These multicenter results indicate that postoperative atrial cardioversion using TADpole Heart Wires is both safe and efficient. It is expected that hospital length of stay and its associated economic impact can be reduced with this therapy.

Medtronic Hall versus St. Jude Medical mechanical aortic valve: downstream turbulences with respect to rotation in pigs.

BACKGROUND AND AIMS OF THE STUDY: Turbulences downstream of mechanical aortic valves are known to contribute to most valve-related complications such as thrombosis, embolization or damage to blood components. In vitro studies have demonstrated the impact of the orientation of prostheses on transvalvular energy loss. This study evaluates the influence of valve orientation on turbulences in the supravalvular aorta in pigs. METHODS: A rotation device which could carry a Medtronic Hall (MH) or St. Jude Medical (SJM) aortic valve prosthesis (23 mm) was constructed and implanted into four healthy pigs. Turbulence measurements using pulsed Doppler ultrasonography were carried out 3 cm downstream of the valve, while the prostheses were rotated in 45 degrees steps. Reynold's normal stress values (RNS) were calculated as key markers for turbulent stresses. RESULTS: Turbulences downstream of MH and SJM valves demonstrated a significant change with rotation. The MH valve showed minimum RNSmean values with orientation of the large orifice to the right posterior aortic wall, which is the area of highest velocities during ejection. With this orientation, aortic flow almost complied with physiologic conditions. Increase of turbulence was observed with any other position. The SJM valve revealed significant turbulent flow at any orientation. Minimum RNSmean values were also measured with one orifice facing the right posterior wall of the aorta. CONCLUSION: With optimum orientation (major orifice facing the right posterior aortic wall) the MH valve matches the aortic flow pattern to near-normal physiology. The flow patterns of the SJM valve are less susceptible to rotation, but cannot attain the optimum RNS values of the MH prosthesis.