Why can pulmonary vein stenoses created by radiofrequency catheter ablation worsen during and after follow-up ? A potential explanation

<p>Abstract</p> <p>Background</p> <p>Radiofrequency catheter ablation of excitation foci inside pulmonary veins (PV) generates stenoses that can become quite severe during or after the follow-up period. Since severe PV stenoses have most often disastrous consequences, it would be important to know the underlying mechanism of this temporal evolution. The present study proposes a potential explanation based on mechanical considerations.</p> <p>Methods</p> <p>we have used a mathematical-physical model to examine the cyclic increase in axial wall stress induced in the proximal (= upstream), non-stenosed segment of a stenosed pulmonary vein during the forward flow phases. In a representative example, the value of this increase at peak flow was calculated for diameter stenoses (DS) ranging from 1 to 99%.</p> <p>Results</p> <p>The increase becomes appreciable at a DS of roughly 30% and rise then strongly with further increasing DS value. At high DS values (e.g. > 90%) the increase is approximately twice the value of the axial stress present in the PV during the zero-flow phase.</p> <p>Conclusion</p> <p>Since abnormal wall stresses are known to induce damages and abnormal biological processes (e.g., endothelium tears, elastic membrane fragmentations, matrix secretion, myofibroblast generation, etc) in the vessel wall, it seems plausible that the supplementary axial stress experienced cyclically by the stenotic and the proximal segments of the PV is responsible for the often observed progressive reduction of the vessel lumen after healing of the ablation injury. In the light of this model, the only potentially effective therapy in these cases would be to reduce the DS as strongly as possible. This implies most probably stenting or surgery.</p

Current status of the European Association for Cardio-thoracic surgery and the society of thoracic surgeons congenital heart surgery database

Background. After utilizing separate congenital databases in the early 1990s, the Society of Thoracic Surgeons (STS) and the European Association for Cardio-Thoracic Surgery (EACTS) collaborated on several joint database initiatives. Methods. In 1998, the joint EACTS-STS International Congenital Heart Surgery Nomenclature and Database Project Committee was created and a common nomenclature and common core minimum database dataset were adopted and published by the STS and the EACTS. In 1999, the joint EACTS-STS Aristotle Committee was created and the Aristotle Score was adopted and published as a method to provide complexity adjustment for congenital heart surgery. Collaborative efforts involving the EACTS and STS are underway to develop mechanisms to verify data completeness and accuracy. Results. Since 1998, this nomenclature, database, and methodology of complexity adjustment have been used by both the STS and EACTS to analyze outcomes of over 40,000 patients. A huge amount of data have been generated which allow comparison of practice patterns and outcomes analysis between Europe and North America. The aggregate data from the first 5 years of data collection not only make for interesting comparison but also allow examination of regional difference in practice patterns. For example, in the EACTS, out of 4,273 neonates, 885 (20.7%) underwent arterial switch procedures and 297 (6.95%) underwent Norwood stage 1 procedures. In the STS, out of 3,988 neonates, 472 (11.8%) underwent arterial switch procedures and 575 (14.4%) underwent Norwood stage 1 procedures. Conclusions. This analysis of the EACTS-STS multi-institutional outcomes database confirms that in both Europe and North America, case complexity and mortality is highest among neonates, then infants, and then children. Regional differences in practice patterns are demonstrated, with the overall goal being the continued upgrade in the quality of surgery for congenital heart disease worldwide

Differential Endothelial Gap Junction Expression in Venous Vessels Exposed to Different Hemodynamics

After being anastomosed with the artery, vein graft is exposed to abruptly increased hemodynamic stresses. These hemodynamic stresses may change the profile of endothelial gap junction expression as demonstrated in the artery, which may subsequently play active roles in physiological adaptation or pathophysiological changes of the vein grafts. We investigated the endothelial expression of gap junction in the venous vessels exposed to different hemodynamic stresses. Immunocytochemical analysis of the endothelial Cx expression was performed by observing the whole mounts of inferior vena cava (IVC) of aortocaval fistula (ACF) rats or IVC-banded ACF rats using confocal microscope. Immunocytochemical analysis demonstrated that in the endothelium of the native vein, the gap-junctional spot numbers (GJSNs) and the total gap-junctional areas (TGJAs) of Cx40 and Cx43 were lower than those of the thoracic aorta and that Cx37 was hardly detectable. In the IVCs of ACF rats, which were demonstrated to be exposed to a hemodynamic condition of high flow velocity and low pressure, the GJSNs and the TGJAs of all three Cxs were increased. In the IVCs of IVC-banded ACF rats, which were exposed to a hemodynamic condition of high pressure and low flow velocity, the GJSNs and the TGJAs of Cx37 increased markedly and those of Cx40 and Cx43 remained without significant changes. In conclusion, the endothelial expressions of gap junctions in the native veins were lower than those of the arteries. When exposed to different hemodynamic stresses, the gap junctions were expressed in specific patterns. (J Histochem Cytochem 58:1083–1092, 2010

Stratification of Complexity Improves the Utility and Accuracy of Outcomes Analysis in a Multi-Institutional Congenital Heart Surgery Database: Application of the Risk Adjustment in Congenital Heart Surgery (RACHS-1) and Aristotle Systems in the Society of Thoracic Surgeons (STS) Congenital Heart Surgery Database

Abstract OBJECTIVE: The valved bovine conduit "Contegra" for RVOT reconstruction became available for clinical use within a 100 % source data monitored and echo core lab controlled prospective European Multicentre Study, carried out from 1999 to 2006. We present the results of this study. METHODS: A total of 165 Contegras were implanted in 8 centres. The mean patient age was 3.9 years (2 days - 18 years, median 2.0). Total follow-up was 687 patient years. Diagnoses included: tetralogy of Fallot (64 patients, 39 %), truncus arteriosus (50, 30 %), double outlet right ventricle (16, 10 %), aortic valve disease/Ross procedure (11, 7 %), pulmonary valve atresia (10, 6 %), transposition of the great arteries (10, 6 %), 4 other malformations (2 %). Previous procedures were: 82 patients (50 %) - none; 37 (22 %) - valved conduit implantation; 14 (8 %) aortopulmonary shunt; 6 (4 %) catheter intervention. Follow-up appointments which included standardised echocardiography investigations were scheduled at 1, 3, 6, and 12 months, then annually. We evaluated freedom from death, explantation, intervention, stenosis, insufficiency, and degeneration. Results were stratified by age, diagnosis group and conduit size. RESULTS: The 5-year freedom-from rates were: explantation - 90 % (for patients aged 1 to 10 years) and 68 % (for younger patients); endocarditis - over 92 %; catheter intervention - 74 % (patients with congenital malformations); stenosis - 75 % and more (any group); insufficiency - 50 % (12 and 14 mm diameter conduits); any event - 13 % (patients under 1 year), 58 % (1 to 10 years), 82 % (> 10 years). Trace or mild insufficiency was a frequent, but not progressive finding. Mild calcification was detected in only 8 examinations. CONCLUSIONS: The performance of the Contegra conduit compares well with that of homografts when used to reconstruct paediatric right ventricular outflow tracts