Variations in cephalic vein venography for device implantation–Relationship to success rate of lead implantation

Introduction: Lead implantation using the cephalic vein (CV) cutdown technique has been well established, but is not always expected to achieve high success rates. We studied the relationship between preoperative CV venography and the success rate of lead implantation. Methods: Two hundred and twenty one CV venographies were performed in 205 patients (mean age 75 years, 113 males). Leads were inserted via the CV cutdown technique with a guidewire and sheath. Variations in CV venography included usage of the right and left CVs. The success rate of lead implantation was studied. Results: No major kink was observed in 71% of the right CV cases and 43% of the left CV cases. Leads were successfully implanted in over 90% of these patients. A major kink in the CV was found in 15% of the right CV cases and 34% of the left CV cases and successful lead implantation was around 80% in this population. The overall success rate tended to be higher for the right side (83%) than for the left side (71%). Conclusion: Severe kinks or variations in the CV that hinder lead manipulation were less frequent in the right CV. Therefore, a higher success rate of lead implantation by the cutdown technique is expected for the right CV

Spatial Simulation Modelling of Future Forest Cover Change Scenarios in Luangprabang Province, Lao PDR

Taking Luangprabang province in Lao Peoples’s Democratic Republic (PDR) as an example, we simulated future forest cover changes under the business-as-usual (BAU), pessimistic and optimistic scenarios based on the Markov-cellular automata (MCA) model. We computed transition probabilities from satellite-derived forest cover maps (1993 and 2000) using the Markov chains, while the “weights of evidence” technique was used to generate transition potential maps. The initial forest cover map (1993), the transition potential maps and the 1993–2000 transition probabilities were used to calibrate the model. Forest cover simulations were then performed from 1993 to 2007 at an annual time-step. The simulated forest cover map for 2007 was compared to the observed (actual) forest cover map for 2007 in order to test the accuracy of the model. Following the successful calibration and validation, future forest cover changes were simulated up to 2014 under different scenarios. The MCA simulations under the BAU and pessimistic scenarios projected that current forest areas would decrease, whereas unstocked forest areas would increase in the future. Conversely, the optimistic scenario projected that current forest areas would increase in the future if strict forestry laws enforcing conservation in protected forest areas are implemented. The three simulation scenarios provide a very good case study for simulating future forest cover changes at the subnational level (Luangprabang province). Thus, the future simulated forest cover changes can possibly be used as a guideline to set reference scenarios as well as undertake REDD/REDD+ preparedness activities within the study area