Genetic and environmental influences on total plasma homocysteine and its role in coronary artery disease risk

BackgroundElevated levels of total plasma homocysteine are a risk factor for atherosclerotic disease.AimsThe rationale behind this study is to explore the correlation between degree and site of coronary lesion and hyperhomocysteinemia in Lebanese CAD patients and assess environmental and genetic factors for elevated levels of total plasma homocysteine.MethodsA total of 2644 patients were analyzed for traditional CAD risk factors. Logistic regression was performed to determine the association of hyperhomocysteinemia with degree and site of coronary lesions controlling for risk factors. Environmental and genetic factors for hyperhomocysteinemia were analyzed by logistic regression using a candidate gene approach.ResultsTraditional risk factors were correlated with stenosis. Hyperhomocysteinemia associated with increased risk of overall stenosis, and risk of mild and severe occlusion in major arteries. Hyperhomocysteinemia and hypertension were highly correlated suggesting that hyperhomocysteinemia acts as a hypertensive agent leading to CAD. Diuretics and genetic polymorphisms in MTHFR and SLCO1B1 were associated with hyperhomocysteinemia.ConclusionsHyperhomocysteinemia is a medical indicator of specific vessel stenosis in the Lebanese population. Hypertension is a major link between hyperhomocysteinemia and CAD occurrence. Genetic polymorphisms and diuretics’ intake explain partly elevated homocysteine levels. This study has important implications in CAD risk prediction.     

Using virtual reality to explore the role of conflict resolution and environmental salience in Freezing of Gait in Parkinson's disease

BackgroundThe freezing phenomenon is among the most disabling symptoms of Parkinson's disease (PD) manifesting most commonly as Freezing of Gait with a paroxysmal cessation of effective stepping. Recent studies have suggested that freezing is related to both impairments in conflict resolution as well as the processing of environmentally salient information.MethodsIn this study, we utilized a virtual reality gait paradigm to investigate differences in motor outflow between PD patients with (n = 36) and without (n = 37) Freezing of Gait, as well as age-matched healthy controls (n = 18). Subjects were required to navigate a realistic on-screen environment with the use of foot pedals to simulate stepping whilst responding to either cues associated with conflict resolution (congruent ‘Red’, ‘Green’ or ‘Blue’) or environmental salience (wide, narrow and sliding doorways). Footstep latency was used as a measure of motor output.ResultsSignificantly increased stepping latencies were observed in freezers compared to non-freezers (p = 0.004) and controls (p = 0.016) in response to stimuli requiring the inhibition of implicitly cued behavior (‘red’ cue). Patients with Freezing of Gait also demonstrated increased motor latency compared to non-freezers and controls specifically in response to environmentally salient triggers including narrow doorways (p = 0.03 and 0.01 respectively) and the opening of a sliding door (p = 0.036 and 0.048 respectively). Performance on the paradigm in relation to these triggers correlated significantly with self-reported freezing severity.ConclusionThese results suggest that deficits in conflict resolution and visuospatial processing may reflect some of the neural mechanisms associated with freezing behavior and that these can be probed in a virtual reality environment.     

Worldwide Experience with the Robotic Navigation System in Catheter Ablation of Atrial Fibrillation: Methodology, Efficacy and Safety

Worldwide Survey on Robotic AF Ablation . Introduction: The Hansen Robotic system has been utilized in ablation procedures for atrial fibrillation (AF). However, because of the lack of tactile feedback and the rigidity of the robotic sheath, this approach could result in higher risk of complications. This worldwide survey reports a multicenter experience on the methodology, efficacy, and safety of the Hansen system in AF ablations. Methods and Results: A questionnaire addressing questions on patient's demographics, procedural parameters, ablation success rate and safety information was sent to all centers where more than 50 robotic AF ablation cases have been performed. From June 2007 to December 2009, 1,728 procedures were performed at 12 centers utilizing the Hansen robotic navigation technology. The overall complication rate was 4.7% and the success rate was 67.1% after 18 ± 4 months of follow‐up. In 5 low volume centers there appeared to be a learning curve of about 50 cases (complication rate 11.2% for the first 50 cases vs 3.7% for the 51–100 cases; P = 0.044) and a trend showing a decrease of complication rate with increasing case volume. However, in the remaining 7 centers no learning curve was present and the complication rate was stable over time (3.7% for the first 50 cases vs 3.6% for the 51st case thereafter; P = 0.942). Conclusion: The Hansen robotic system can be used for AF ablation safely. In low volume centers, there appeared to be a learning curve of the first 50 cases after which the complication rate decreased. With a higher case volume, the success rate increased. (J Cardiovasc Electrophysiol, Vol. 23, pp. 820‐826, August 2012)