Design and Evaluation of a Catheter Contact-Force Controller for Cardiac Ablation Therapy.

GOAL: Maintaining a constant contact force (CF) of an ablation catheter during cardiac catheter ablation therapy is clinically challenging due to inherent myocardial motion, often resulting in poor ablation of arrhythmogenic substrates. To enable a prescribed contact force to be applied during ablation, a catheter contact force controller (CCFC) was developed. METHODS: The system includes a hand-held device attached to a commercial catheter and steerable sheath. A compact linear motor assembly attaches to an ablation catheter and autonomously controls its relative position within the shaft of the steerable sheath. A closed-loop control system is implemented within embedded electronics to enable real-time catheter-tissue contact force control. To evaluate the performance of the CCFC, a linear motion phantom was used to impose a series of physiological CF profiles; lesion CF was controlled at prescribed levels ranging from 15 to 40 g. RESULTS: For a prescribed CF of 25 g, the CCFC was able to regulate the CF with a root mean squared error of 3.7 ± 0.7 g. The ability of the CCFC to retract the catheter upon sudden changes in tissue motion, which may have caused tissue damage, was also demonstrated. Finally, the device was able to regulate the CF for a predetermined amount of time according to a force-time integral model. CONCLUSION: The developed CCFC is capable of regulating catheter-tissue CF in a laboratory setting that mimics clinical ablation therapy. SIGNIFICANCE: Catheter-tissue CF control promises to improve the precision and success of ablation lesion delivery

Omega-3 fatty acid supplements improve the cardiovascular risk profile of subjects with metabolic syndrome, including markers of inflammation and auto-immunity

OBJECTIVE Fish-oil contains high concentrations of omega-3 fatty acids that have been shown to have anti-inflammatory properties. We have evaluated the effects of purified omega-3 fatty acid supplements on several anthropometric and biochemical parameters, including heat shock protein (Hsp) 27 antibody titres in subjects with metabolic syndrome. METHODS Subjects (n = 120) with metabolic syndrome (mean age of 52.9 +/- 11.9 years) were randomly allocated to one of two groups: sixty subjects were given 1 gram of fish oil as a single capsule, containing 180 mg eicosapentaenoic acid and 120 mg docosahexaenoic acid daily for 6 months. Control subjects did not receive any supplementation over the same period. RESULTS The study was completed by 47 subjects in the intervention group and 42 subjects in the control group. Treatment with omega 3 supplements was associated with a significant fall in body weight (P < 0.05), systolic blood pressures (P < 0.05), serum low density lipoprotein cholesterol (P < 0.05), and total cholesterol (P < 0.05), triglycerides (P < 0.05), high-sensitivity C-reactive protein (hs-CRP) (P < 0.01), and Hsp27 antibody titres (P < 0.05). No significant changes were observed in the control group. CONCLUSION It appears that omega 3 improves the cardiovascular risk profile of subjects with metabolic syndrome, having effects on weight, systolic blood pressure, lipid profile and markers of inflammation and autoimmunit