Choosing the right type of serum for different applications of human adipose tissue-derived stem cells: influence on proliferation and differentiation abilities.

BACKGROUND AIMS: Adipose tissue-derived stem cells (ADSCs) are thought to have great potential in regenerative medicine. A xenoprotein-free culture and handling system is desirable. To date, there is only little and contradictory information about the influence of the different types of human serum on ADSC proliferation and differentiation. METHODS: First, ADSCs were cultured in media containing regular human serum (HS plus) or fetal calf serum (FCS plus) with supplementation of growth factors for three passages. During passage 4, ADSC proliferative activity and adipogenic, osteogenic and chondrogenic differentiation ability was quantified. Second, ADSCs were cultured with three different human sera (regular human serum [HS], human serum from platelet-poor plasma [SPPP] or human serum from platelet-rich plasma [SPRP]) without supplementation of platelet-derived growth factor and assessed accordingly. The growth factor content of the different types of human sera was determined by means of multiplex protein assay and enzyme-linked immunosorbent assay. RESULTS: The different sera did not affect ADSC doubling time significantly (P < 0.05). Specific glycerol-3-phosphat-dehydrogenase activity was significantly lower in cultures with SPRP (P < 0.01) compared with the other media compositions. Extracellular calcium deposition was significantly higher in cells differentiated in cultures with HS or SPPP compared with those with SPRP, HS plus or FCS (P < 0.01). Glycosaminoglycan content and collagen 2 were highest in cells cultured with SPRP (P < 0.001). CONCLUSIONS: Culturing ADSCs in human serum appears to be a reasonable and efficient alternative compared with FCS. With respect to the outcome of a sighted clinical application, it appears to be feasible to handle the cells in a serum suitable for the intended later use.

Association of echocardiographic atrial size and atrial fibrosis in a sequential model of congestive heart failure and atrial fibrillation.

BACKGROUND: Cardioversion (CV) success of atrial fibrillation (AF) inversely correlates to the size of the left atrium (LA). Atrial fibrillation and its most important risk factor, congestive heart failure (CHF), both induce atrial structural enlargement and fibrosis. To investigate the effect of AF and CHF on atrial dilatation and fibrosis, and to estimate whether echocardiographically determined atrial size may be used as a marker for atrial fibrosis. METHODS: In six dogs, pacemakers were implanted followed by HIS bundle ablation. After 4 weeks of rapid ventricular stimulation (185 bpm) for CHF induction, additional rapid atrial stimulation (500 bpm) was maintained for 7 weeks to induce AF. Serial determinations of echocardiographic atrial size were performed. Seven dogs with sinus rhythm served as histological controls. Postmortem tissue was obtained to determine the degree and composition of atrial fibrosis. RESULTS: While the ejection fraction of the AF/CHF dogs decreased significantly from 57+/-5% to 19+/-7% (P<.01), an increased degree of atrial fibrosis was found (right atrium [RA], 4.9+/-2.0% to 19.9+/-5.4%; LA, 4.4+/-1.6% to 22.2+/-3.2%; P<.01), accompanied by a significant increase of atrial volumes (LA: 21+/-4 to 44+/-4 mm3; P<.01; RA: 10+/-3 to 18+/-6 mm3; P<.05) and LA diameters (34+/-4 to 43+/-2 mm, P<.05). Atrial fibrosis and size significantly correlated. CONCLUSIONS: Atrial fibrillation/CHF leads to a significant atrial fibrosis and dilation. The increased echocardiographic size correlates to the degree of atrial fibrosis and may be used as clinical marker for atrial fibrosis. The fibrosis accompanying atrial dilatation may also explain why LA size, as determined by echocardiography, is a strong predictor of CV success.

Integration of automatic intrathoracic fluid content measurement into clinical decision making in patients with congestive heart failure.

BACKGROUND: Hospitalizations due to decompensation are a frequent problem in treating patients with congestive heart failure (CHF). Continuous impedance measurement via implantable devices may detect pulmonary fluid accumulation due to worsening CHF. An acoustic alert might allow an earlier treatment of impending decompensation. An algorithm that implemented impedance measurement into clinical decision making in treating CHF patients was evaluated. METHODS: Forty-two CHF patients (ejection fraction: 27 +/- 6%; New York Heart Association 2.9 +/- 0.6) with cardiac resynchronization therapy and automatic impedance measurements were included. Upon an alert, a stepped therapy was initiated: category (1) overt decompensation, hospitalization; category (2) worsened CHF, increase of diuretics; category (3) no CHF worsening, brain natriuretic peptide (BNP) measurement, elevated BNP: increase of diuretics, normal BNP: no specific treatment. RESULTS: During 18 +/- 4 months, 45 alerts were treated according to the algorithm. Eleven category 1 alerts led to hospitalization; 21 category 2 and 11 category 3 patients (elevated BNP) were treated conservatively. Two category 3 alerts (normal BNP) received no treatment. CONCLUSIONS: Automatic impedance measurement can be integrated into CHF management. BNP measurement restricted to patients with alert but without clinical signs of worsened CHF may prevent premature therapy escalation.

Catheter ablation of persistent atrial fibrillation : Beneficial effect of a short-term adjunctive amiodarone therapy on the long-term outcome.

BACKGROUND: Catheter ablation has become the first line therapy in patients with symptomatic, recurrent, drug-refractory atrial fibrillation. Circumferential pulmonary vein ablation is still the standard approach in these patients. However, the results are not very favorable (especially in patients with persistent atrial fibrillation). Therefore, more complex ablation strategies and the usefulness of (short-term) adjunctive antiarrhythmic drug therapy are a matter of discussion. The aim of this study was to analyze whether short-term amiodarone therapy after catheter ablation (3 months) has a positive effect on the success rates after circumferential pulmonary vein ablation in patients with persistent atrial fibrillation. METHODS: A total of 230 consecutive patients with symptomatic persistent atrial fibrillation underwent a circumferential pulmonary vein ablation procedure (using the NAVX or CARTO system). Catheter ablation of the right or left atrial isthmus and a linear lesion in the roof of the left atrium were only performed in selected patients with documented episodes of atrial fibrillation. In 115 patients, a short-term adjunctive antiarrhythmic drug therapy with amiodarone was initiated immediately prior to the ablation procedure (for the first 3 months group A). In the remaining 115 patients, no antiarrhythmic drug therapy was administered except for beta blockers (group B). RESULTS: Out of 115 patients 19 (16.5%) in group A and 34 (29.6%) in group B experienced an arrhythmia recurrence within the first 3 months after ablation requiring electrical cardioversion (P = 0.03; blanking period). One year after the ablation procedure 81.7% of patients in group A (94/115) and 73.0% of patients in group B (84/115) were free from further arrhythmia recurrences (P = 0.16). The success rate 2 years after catheter ablation was 76.5% (no arrhythmia recurrence in 88/115 patients) in group A and 63.5% in group B (no arrhythmia recurrence in 73/115 patients; P = 0.04). There were no major complications during long-term follow-up. CONCLUSION: Adjunctive short-term amiodarone therapy improves the success rate after catheter ablation of persistent atrial fibrillation during long-term follow-up. This might be due to a decreased incidence of early arrhythmia recurrences after catheter ablation of atrial fibrillation and an improved reverse remodelling process.

Decreased plasminogen activator inhibitor and tissue metalloproteinase inhibitor expression may promote increased metalloproteinase activity with increasing duration of human atrial fibrillation.

INTRODUCTION: Atrial fibrosis has been shown to concur with the persistence of atrial fibrillation (AF) and is only incompletely reversible, thus counteracting attempts to restore and maintain sinus rhythm (SR). Besides the angiotensin system, the matrix metalloproteinases (MMP) play a major role in the pathogenesis of fibrosis. Thus, the present study investigated changes of the MMP system during the development of human AF. METHODS AND RESULTS: Right atrial appendages of 146 patients were excised during heart surgery and grouped according to rhythm (SR vs AF) and AF duration. Hydroxyproline as a surrogate for collagen content and morphometrically determined collagen content increased significantly from SR (14.3 +/- 7.7%) to chronic permanent AF (CAF) of 6-24 months (21.2 +/- 9.2%, P = 0.02), and CAF of > 60 months (25.3 +/- 4.7%, P < 0.01). From SR to paroxysmal and chronic persistent AF (CPAF) and to CAF MMP-2 and MMP-9 activity rose, while their mRNA and protein levels were not altered significantly. Plasminogen activator inhibitor (PAI), an inhibitor of a potent activator of many MMPs, was significantly decreased with increasing duration of AF. In parallel, the mRNA levels of the tissue inhibitors of MMPs TIMP-1 and -2 decreased significantly. CONCLUSION: Human atrial fibrogenesis is enhanced with increasing duration of AF: a longer AF duration is associated with elevated atrial interstitial MMP activity, but decreased PAI and TIMP expression.

Radiofrequency catheter ablation for redo procedures after pulmonary vein isolation with the cryoballoon technique : Long-term outcome.

BACKGROUND: Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug-refractory atrial fibrillation (AF). Cryoablation has been shown to be a safe and effective technique for pulmonary vein (PV) isolation. However, the arrhythmia recurrence rate is high after cryoablation procedures. Radiofrequency catheter ablation has been shown to be an effective strategy for redo procedures in these patients and to provide a favourable outcome during midterm follow-up. The aim of this study was to analyse whether the strategy also provides favourable results during long-term follow-up (5 years). METHODS: In this study 30 patients (paroxysmal AF: 22 patients, persistent AF: 8 patients) underwent a redo procedure after initially successful circumferential PV isolation with the cryoballoon technique (Arctic Front Balloon, Medtronic). The redo ablation procedures were performed using a segmental approach or a circumferential ablation strategy (CARTO; Biosense Webster, Diamond Bar, CA, USA) depending on the intraprocedural findings. RESULTS: During the repeat procedure, a mean number of 2.9 reconnected PV (SD ± 1.0) were detected. In 20 patients, a segmental approach was sufficient to eliminate the residual PV conduction because only a few PV fibres were recovered (1-3 reconnected PV; group A). In the remaining 10 patients, a circumferential ablation strategy was used because of a complete recovery of the pulmonary vein - left atrial (PV-LA) conduction (group B). All reconnected PV were isolated successfully again. A third or fourth ablation procedure had to be performed in 4 (3 and 1, respectively) patients (13.3%). At 5­year follow-up, 66.7% of all patients were free from an arrhythmia recurrence (20 out of 30). There were no major complications during long-term follow-up. CONCLUSION: In patients with an initial circumferential PV isolation using the cryoballoon technique, a repeat ablation procedure can be safely and effectively performed using radiofrequency catheter ablation providing good long-term follow-up results.

Catheter ablation of persistent atrial fibrillation : Circumferential pulmonary vein ablation: beneficial effect of an additional linear lesion at the roof of the left atrium on the long-term outcome.

BACKGROUND: Circumferential pulmonary vein ablation is still the standard approach in patients with persistent atrial fibrillation. However, the results are not very favourable and more complex ablation strategies are the subject of current controversy. Therefore, we have evaluated the effect of an additional linear lesion at the roof of the left atrium on the long-term outcome. METHODS: A total of 125 patients with symptomatic persistent atrial fibrillation underwent a circumferential pulmonary vein ablation procedure in combination with an additional linear lesion at the roof of the left atrium (group A). The long-term follow-up data was compared to 125 patients with similar clinical characteristics who underwent circumferential pulmonary vein ablation without an additional linear lesion at the roof of the left atrium (group B). RESULTS: The ablation procedure could be performed as planned in all 250 patients. Three years after catheter ablation, the success rate was 72.0% (no arrhythmia recurrence in 90 out of 125 patients) in group A and 63.2% in group B (no arrhythmia recurrence in 79 out of 125 patients; P = 0.04). There were no major complications. CONCLUSIONS: Catheter ablation of persistent atrial fibrillation comprising a circumferential pulmonary vein ablation and an additional linear lesion at the roof of the left atrium provides more favourable long-term results than circumferential pulmonary vein ablation alone.

Catheter ablation of atrial fibrillation facilitated by preprocedural three-dimensional transesophageal echocardiography: Long-term outcome.

AIM: To evaluate the long-term outcome of catheter ablation of atrial fibrillation (AF) facilitated by preprocedural three-dimensional (3-D) transesophageal echocardiography. METHODS: In 50 patients, 3D transesophageal echocardiography (3D TEE) was performed immediately prior to an ablation procedure (paroxysmal AF: 30 patients, persistent AF: 20 patients). The images were available throughout the ablation procedure. Two different ablation strategies were used. In most of the patients with paroxysmal AF, the cryoablation technique was used (Arctic Front Balloon, CryoCath Technologies/Medtronic; group A2). In the other patients, a circumferential pulmonary vein ablation was performed using the CARTO system [Biosense Webster; group A1 (paroxysmal AF), group B (persistent AF)]. Success rates and complication rates were analysed at 4-year follow-up. RESULTS: A 3D TEE could be performed successfully in all patients prior to the ablation procedure and all four pulmonary vein ostia could be evaluated in 84% of patients. The image quality was excellent in the majority of patients and several variations of the pulmonary vein anatomy could be visualized precisely (e.g., common pulmonary vein ostia, accessory pulmonary veins, varying diameter of the left atrial appendage and its distance to the left superior pulmonary vein). All ablation procedures could be performed as planned and almost all pulmonary veins could be isolated successfully. At 48-mo follow-up, 68.0% of all patients were free from an arrhythmia recurrence (group A1: 72.7%, group A2: 73.7%, group B: 60.0%). There were no major complications. CONCLUSION: 3D TEE provides an excellent overview over the left atrial anatomy prior to AF ablation procedures and these procedures are associated with a favourable long-term outcome.

Catheter ablation of persistent atrial fibrillation : Long-term results of circumferential pulmonary vein ablation in combination with a linear lesion at the roof of the left atrium.

BACKGROUND: Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug-refractory atrial fibrillation. However, catheter ablation of persistent atrial fibrillation is still a challenge. Various relatively complex ablation strategies exist and their results are not very favorable. Therefore, the aim of our study was to evaluate a well-defined reasonable approach to catheter ablation of persistent atrial fibrillation. The strategy consisted of a circumferential pulmonary vein ablation in combination with a linear lesion at the roof of the left atrium. METHODS: A total of 150 patients with symptomatic persistent atrial fibrillation were enrolled in this study. All patients underwent catheter ablation of persistent atrial fibrillation using the abovementioned approach. RESULTS: The ablation procedure could be performed as planned in all 150 patients. Five years after catheter ablation, the success rate was 71.3% (no arrhythmia recurrence in 107 out of 150 patients). There were no major complications during long-term follow-up. CONCLUSION: Catheter ablation of persistent atrial fibrillation can be performed safely and effectively using this ablation strategy providing favorable long-term follow-up results.

Catheter ablation of paroxysmal atrial fibrillation: circumferential pulmonary vein ablation: success rates with and without exclusion of areas adjacent to the esophagus.

BACKGROUND: Catheter ablation has become the first line of therapy in patients with symptomatic, recurrent, drug-refractory paroxysmal atrial fibrillation. Circumferential pulmonary vein ablation is still the standard approach in these patients. The occurrence of an atrioesophageal fistula is a rare but life-threatening complication after such ablation procedures. This is due to the fact that the esophagus does frequently have a very close anatomical relationship to the left or right pulmonary vein ostia. The aim of our study was to evaluate whether the exclusion of areas adjacent to the esophagus does have a significant effect on the success rate after circumferential pulmonary vein ablation. METHODS: Two hundred consecutive patients [121 men, 69 women; mean age 59.1 years (SD ± 11.3 years)] with symptomatic paroxysmal atrial fibrillation underwent a circumferential pulmonary vein ablation procedure (using the CARTO- or the NAVX-system). In 100 patients, a complete circumferential pulmonary vein ablation was attempted regardless of the anatomical relationship between the ablation sites and the esophagus (group A). In the remaining 100 patients, the esophagus was marked by a special EP catheter and areas adjacent to the esophagus were excluded from the ablation procedure. After discharge, patients were scheduled for repeated visits at the arrhythmia clinic at 1, 3, 6, 9, 12, 24 and 36 months after the ablation procedure. RESULTS: The ablation procedure could be performed as planned in all 200 patients. In group A, all pulmonary veins could be isolated successfully in 88 out of 100 patients (88%). A mean number of 3.9 pulmonary veins (SD ± 0.37 PVs) were isolated per patient. The 12 cases of an incomplete pulmonary vein isolation were due to poorly accessible pulmonary vein ostia. In group B, all pulmonary veins could be isolated successfully in only 58 out of 100 patients (58%; P < 0.01). A mean number of 3.5 PVs (SD ± 0.6 PVs) were isolated per patient (P < 0.01). This was mostly due to a close anatomical relationship to the esophagus. The ablation strategy had to be modified in 46/100 patients in group B because of a close anatomical relationship between the right (n = 25) or left (n = 21) pulmonary vein ostia and the esophagus. One year after the ablation procedure, 87% of patients in group A (87/100) and 79% of patients in group B (79/100) were free from an arrhythmia recurrence (P = 0.19). Three years after catheter ablation, the success rate was 80% (no arrhythmia recurrence in 80 out of 100 patients) in group A and 66% in group B (no arrhythmia recurrence in 66 out of 100 patients; P = 0.04). There were no major complications during long-term follow-up. CONCLUSIONS: The exclusion of areas adjacent to the esophagus results in a markedly higher percentage of incompletely isolated pulmonary veins after circumferential pulmonary vein ablation procedures. This results in a significantly higher arrhythmia recurrence rate during long-term follow-up.

The impact of human adipose tissue-derived stem cells on breast cancer cells: implications for cell-assisted lipotransfers in breast reconstruction.

BACKGROUND: In this study we evaluated the interactions of human adipose tissue-derived stem cells (ADSCs) and different human breast cancer cell lines (BRCAs) with regard to the safety of cell-assisted lipotransfers for breast reconstruction and a thereby unintended co-localization of ADSCs and BRCAs. METHODS: ADSCs were co-cultured with five different human BRCAs (MCF-7, MDA-MB-231, SK-BR-3, ZR-75-30, and EVSA-T) and primary BRCAs from one patient in a transwell system, and cell-cell-interactions were analyzed by assessing doubling time, migration and invasion, angiogenesis, quantitative real-time polymerase chain reaction (PCR) of more than 300 tumor-associated genes, and multiplex protein assays of 20 chemokines and growth factors and eight matrix metalloproteinases (MMPs). Results of co-culture were compared to those of the respective monoculture. RESULTS: Quantitative real-time PCR revealed remarkable changes in the expression of multiple tumor-associated genes in co-culture compared to monocultures of both ADSCs and BRCAs. Concomitantly, the concentration of several tumor-associated proteins, such as cytokines and MMPs, were strongly increased in co-culture. Furthermore, exclusively in co-culture with ADSCs, the different BRCAs were exposed to several important tumor-modulating proteins, such as CCL2, HGF, or interleukins. Co-culture did not significantly affect cellular proliferation of either ADSCs or BRCAs (p > 0.05). The migration of MCF-7 and MDA-MB-231 BRCAs was significantly increased in co-culture with ADSCs by a mean of 11% and 23%, respectively (p = 0.04 and 0.012), as well as that of ADSCs in co-culture with MDA-MB-231, ZR-75-30, and EVSA-T (+11-15%, p = 0.035-0.045). Co-culture with MDA-MB-231, SK-BR-3, and EVSA-T BRCAs significantly increased the invasive behavior of ADSCs by a mean of 24-41% (p = 0.014-0.039). There were no significant differences in the in vitro invasive properties of BRCAs in co-culture compared to monoculture. An in vitro angiogenesis assay revealed an increased tube formation of conditioned media from co-cultured BRCAs and ADSCs compared to the respective monocultures. CONCLUSION: This study further elucidates the possible interactions of primary human ADSCs with human BRCAs, pointing towards a potential increased oncological risk which should not be neglected when considering a clinical use of cell-assisted lipoaspirates in breast reconstruction.

Semi-automated 3-dimensional intracardiac echocardiography: development and initial clinical experience of a new system to guide ablation procedures.

BACKGROUND: Pre-interventional three-dimensional (3D) reconstruction of the heart by CT or MRI provides important information on cardiac anatomy for electrophysiological interventions. However, updates of 3D-imaging modalities with high soft-tissue contrast are not available during ablation procedures. OBJECTIVE: We describe the development and first clinical testing of a close to real-time visualization of cardiac anatomy by intracardiac echocardiography (ICE). METHODS: An electronic phased-array 5-10 MHz ICE-catheter (AcuNav/Siemens/64 elements) was inserted via a straightened femoral vein sheath (12F) and placed in the right atrium in 5 pigs. A custom-made prototype stepper motor allowed automatic rotation around the longitudinal axis from 90 degrees to 360 degrees in 2-5 degrees steps. For every plane 2D images of a complete cardiac cycle were acquired, triggered by respiration and ECG. The ultrasound images were digitized and 3D-reconstruction was performed by a prototype software. After experimental validation the system was tested in 6 patients during electrophysiological studies. RESULTS: From a single location in the right atrium, 3D-acquisition and reconstruction of both atria and ventricles with good image quality were achieved within 3-5 minutes. Doppler-mode facilitated identification of the great vessels including the pulmonary veins and their entry into the heart. 3D-visualization of ablation catheters was also possible in all patients and pigs. CONCLUSION: Semi-automated 3D intracardiac echocardiography from a single site inside the right atrium provides the electrophysiologist with a detailed image of both atria and ventricles with repeated updates of the cardiac anatomy.

Mixed chimerism of cardiomyocytes and vessels after allogeneic bone marrow and stem-cell transplantation in comparison with cardiac allografts.

Controversy persists about mixed chimerism (mCh) occurring in the hearts of patients after orthotopic cardiac transplantation in comparison with allogeneic bone marrow (BM) and peripheral blood stem-cell (PBSC) transplants. Cadaver hearts were examined after sex-mismatched transplantation by immunophenotyping combined with dual color fluorescence in situ hybridization (X and Y chromosome-specific probes). A striking disparity in the extent of mCh depending on the different transplantation procedures was recognizable. After allografting with PBSCs, 1.7% chimeric cardiomyocytes were detectable contrasting 5.4% of donor cells after full BM transplantation. In cardiac transplants, host-type endothelial cells (16.2%) and myocytes (14.3%) of the vessel walls were more often encountered than after BM and PBSC allografting. A sprouting of vascular structures into the donor heart after orthotopic cardiac transplantation has to be assumed, as does a pivotal role of the mesenchymal stem cells of the BM in the development of mCh.

Alterations of gene expression and protein synthesis in co-cultured adipose tissue-derived stem cells and squamous cell-carcinoma cells: consequences for clinical applications.

INTRODUCTION: This is the first study evaluating the interactions of human adipose tissue derived stem cells (ADSCs) and human squamous cell carcinoma cells (SCCs), with regard to a prospective cell-based skin regenerative therapy and a thereby unintended co-localization of ADSCs and SCCs. METHODS: ADSCs were co-cultured with A431-SCCs and primary SCCs (pSCCs) in a transwell system, and cell-cell interactions were analyzed by assessing doubling time, migration and invasion, angiogenesis, quantitative real time PCR of 229 tumor associated genes, and multiplex protein assays of 20 chemokines and growth factors and eight matrix metalloproteinases (MMPS). Results of co-culture were compared to those of the respective mono-culture. RESULTS: ADSCs' proliferation on the plate was significantly increased when co-cultured with A431-SCCs (P = 0.038). PSCCs and ADSCs significantly decreased their proliferation in co-culture if cultured on the plate (P <0.001 and P = 0.03). The migration of pSCC was significantly increased in co-culture (P = 0.009), as well as that of ADSCs in A431-SCC-co-culture (P = 0.012). The invasive behavior of pSCCs and A431-SCCs was significantly increased in co-culture by a mean of 33% and 35%, respectively (P = 0.038 and P <0.001). Furthermore, conditioned media from co-cultured ADSC-A431-SCCs and co-cultured ADSCs-pSCCs induced tube formation in an angiogenesis assay in vitro. CONCLUSIONS: This is the first study evaluating the possible interactions of primary human ADSCs with human SCCs, pointing towards a doubtlessly increased oncological risk, which should not be neglected when considering a clinical use of isolated human ADSCs in skin regenerative therapies.

Catheter ablation of atrial fibrillation: Radiofrequency catheter ablation for redo procedures after cryoablation.

AIM: To evaluate the effectiveness of two different strategies using radiofrequency catheter ablation for redo procedures after cryoablation of atrial fibrillation. METHODS: Thirty patients (paroxysmal atrial fibrillation: 22 patients, persistent atrial fibrillation: 8 patients) had to undergo a redo procedure after initially successful circumferential pulmonary vein (PV) isolation with the cryoballoon technique (Arctic Front Balloon, CryoCath Technologies/Medtronic). The redo ablation procedures were performed using a segmental approach or a circumferential ablation strategy (CARTO; Biosense Webster) depending on the intra-procedural findings. After discharge, patients were scheduled for repeated visits at the arrhythmia clinic. A 7-day Holter monitoring was performed at 3, 12 and 24 mo after the ablation procedure. RESULTS: During the redo procedure, a mean number of 2.9 re-conducting pulmonary veins (SD ± 1.0 PVs) were detected (using a circular mapping catheter). In 20 patients, a segmental approach was sufficient to eliminate the residual pulmonary vein conduction because there were only a few recovered pulmonary vein fibres. In the remaining 10 patients, a circumferential ablation strategy was used because of a complete recovery of the PV-LA conduction. All recovered pulmonary veins could be isolated successfully again. At 2-year follow-up, 73.3% of all patients were free from an arrhythmia recurrence (22/30). There were no major complications. CONCLUSION: In patients with an initial circumferential pulmonary vein isolation using the cryoballoon technique, a repeat ablation procedure can be performed safely and effectively using radiofrequency catheter ablation.

Human adipose tissue derived stem cells promote liver regeneration in a rat model of toxic injury.

In the light of the persisting lack of donor organs and the risks of allotransplantations, the possibility of liver regeneration with autologous stem cells from adipose tissue (ADSC) is an intriguing alternative. Using a model of a toxic liver damage in Sprague Dawley rats, generated by repetitive intraperitoneal application of retrorsine and allyl alcohol, the ability of human ADSC to support the restoration of liver function was investigated. A two-thirds hepatectomy was performed, and human ADSC were injected into one remaining liver lobe in group 1 (n = 20). Injection of cell culture medium performed in group 2 (n = 20) served as control. Cyclosporine was applied to achieve immunotolerance. Blood samples were drawn weekly after surgery to determine liver-correlated blood values. Six and twelve weeks after surgery, animals were sacrificed and histological sections were analyzed. ADSC significantly raised postoperative albumin (P < 0.017), total protein (P < 0.031), glutamic oxaloacetic transaminase (P < 0.001), and lactate dehydrogenase (P < 0.04) levels compared to injection of cell culture medium alone. Transplanted cells could be found up to twelve weeks after surgery in histological sections. This study points towards ADSC being a promising alternative to hepatocyte or liver organ transplantation in patients with severe liver failure.

Update on pharmacologic approaches to prevent thromboembolism in atrial fibrillation: are thrombin and factor Xa inhibitors the ultimate answer?

Atrial fibrillation (AF) is the most common clinically relevant cardiac arrhythmia. Prevalence and incidence rates are rising with the advancing population age. A severe complication of untreated AF is thrombus formation in the left atrial appendage with consecutive peripheral thromboembolism. Thus, AF is a major contributor to thromboembolic events, especially in the elderly. Depending on the CHADS2 score for thromboembolic events that takes into account congestive heart failure, hypertension, age, diabetes mellitus and stroke as risk factors, oral anticoagulation therapy with vitamin K antagonists is currently the treatment of choice for the prevention of thromboembolism. However, due to drawbacks of current anticoagulation therapy new substances for oral therapy are currently evaluated in various clinical studies. This article provides an up to date overview of orally active compounds for the future treatment of AF. Emphasis lies on comparison of direct thrombin inhibitors with factor Xa inhibitors that are currently investigated in clinical phase III studies for the treatment of non-valvular AF. The direct thrombin inhibitor dabigatran will be compared with factor Xa inhibitors like rivaroxaban and apixaban. Other promising agents currently investigated in phase II trials such as direct factor Xa inhibitors DU-176b (edoxaban) and YM150, will also be discussed.

Atrial fibrosis and atrial fibrillation: the role of the TGF-ß1 signaling pathway.

BACKGROUND: Atrial fibrosis concurs with chronic atrial fibrillation (AF), a phenomenon that contributes to the resistance to restore and maintain sinus rhythm (SR). Fibrogenesis represents a complex process in which the transforming growth factor-ß1 (TGF-ß1) pathway may play a major role, e.g. in the setting of myocardial infarction. The present study addresses the potential contribution of the TGF-ß1 signaling pathway to atrial fibrosis in patients with AF. METHODS AND RESULTS: Right atrial appendages of 163 patients were excised during heart surgery and grouped according to rhythm (SR vs. AF) and AF duration. Five groups were defined: SR, paroxysmal/chronic persistent AF (<6 months), chronic permanent AF (CAF) of 7-24 months, 25-60 months, and >60 months duration. Collagen content of atria, determined morphometrically, revealed a steady and significant increase in patients with SR (14.6±8.9%) up to patients with CAF of >60 months (28.1±7.1%). Likewise, expression of TGF-ß1 mRNA and protein, TGF-ß-receptor-II protein, profibrotic phospho-Smad-2 and -4 proteins increased. However, the TGF-ß(1) effect appeared to decline with increasing AF duration, characterized by a decrease in TGF-ß-receptor-I protein, increases of TGF-ß inhibiting Smad-7 protein and a reduction of ph-Smad-2. CONCLUSIONS: Human atrial fibrogenesis in patients with atrial fibrillation is accompanied by a biphasic response, an early increase and later loss of responsiveness to TGF-ß(1). It appears that fibrosis progresses despite compensatory changes in the TGF-ß-signaling pathway. The sequential changes in the contribution of different profibrotic processes during the establishment of AF may offer the opportunity to selectively interfere with the atrial remodeling process at different stages.

Atrial fibrillation is associated with cardiac hypoxia.

BACKGROUND: Atrial fibrillation (AF), the most common human arrhythmia, is responsible for substantial morbidity and mortality and may be promoted by selective atrial ischemia and atrial fibrosis. Consequently, we investigated markers for hypoxia and angiogenesis in AF. METHODS: Right atrial appendages (n=158) were grouped according to heart rhythm [sinus rhythm (SR) or AF]. The degree of fibrosis and microvessel density of all patients were determined morphometrically using Sirius-Red- and CD34/CD105-stained sections, respectively. Next, sections (n=77) underwent immunostaining to detect hypoxia- and angiogenesis-related proteins [hypoxia-inducible factor (HIF)1 alpha, HIF2 alpha, vascular endothelial growth factor (VEGF), VEGF receptor 2 (KDR), phosphorylated KDR (pKDR), carboanhydrase IX, platelet-derived growth factor] and the apoptosis-related B-cell lymphoma 2 protein. RESULTS: Fibrosis progressed significantly from 14.7+/-0.8% (SR) to 22.3+/-1.4% (AF). While the positive cytoplasmic staining of HIF1 alpha, HIF2 alpha, VEGF, KDR, and pKDR rose significantly from SR to AF, their nuclear fractions fell (only pKDR significantly). The median CD34/CD105-positive microvessel size increased significantly from SR to AF. CONCLUSIONS: AF is closely associated with an atrial up-regulation of hypoxic and angiogenic markers. Whether this is cause, effect, or co-phenomenon of fibrosis remains to be investigated. It is conceivable that fibrosis might lead to an increased O(2) diffusion distance and thus induce ischemic signaling, which, in turn, leads to angiogenesis.