A New Anti-B Lectin

Anti-B lectins were extracted from the dried and aged seed cover (aril) of an Evonymus variety. After 20 months of aging these lectins resembled the best hitherto described. They were specifically inhibited by B substance of human and horse origin.     

A New Efficient NanoTip Lead

STOKES, K., ET AL.: A New Efficient NanoTip Lead. The ideal lead has low, stable acute and chronic thresholds, high pacing impedance, and good sensing. Leads with low, stable thresholds have been developed, but pacing impedance has been in the 600 Ω region. One way to increase pacing impedance is to decrease the electrode's surface area. The threshold performance and sensing ability of < 5 mm² electrodes have been considered questionable, up to now. We have developed α 1.5 mm² porous, platinized, steroid-eluting electrode and have demonstrated in canine studies that it has excellent performance. Chronic thresholds are low at about 0.65 ± 0.28 V (ventricular) and 0.42 ± 0.12 V (atrial) at 0.5 msec. Chronic pacing impedance is in the 1200–1300 Ω region, but mean chronic R and P wave source impedance is ≤ 1500 Ω. Sensing is excellent, with almost double the P wave amplitudes usually measured in the canine.     

A New Steroid-Eluting Screw-In Electrode

A new lead design was tested that combined a small microporous steroid-eluting electrode with an insulated, exposed helix for active fixation. This lead (model 5078, Medtronic, Inc., group I. n = 10) was compared to a conventional model (model Y 60 BP, Biotronik) with a larger surface of polished platinum-iridium, equipped with a fixed, noninsulated screw but without steroid elution (group II, n = 10). The two lead models were studied in the atrial position of dual chamber pacing systems, which all had a tined ventricular lead (model 5024, Medtronic, Inc.), with essentially the same steroid-aluting tip as the new active fixation lead design. Sensing and pacing data were recorded acutely and during 1 year of follow-up, via the telemetry of a Relay pulse generator (Intermedics. Inc.). Intraoperatively, unfiltered atrial electrogram amplitudes did not differ between groups (group I; 7.12 ± 2.56 mV vs group II: 6.42 ± 1.87 mV; P > 0.05), nor did sensing thresholds 1 year after implantation (group I: 5.33 ± 1.70 mV vs group II: 4.26 ± 1.40 mV; P > 0.05). Atrial pacing thresholds as measured during surgery at a pulse width of 0.5 msec were lower in group I (0.49 ± 0.15 V) than in group II (0.68 ± 0.19 V; P < 0.05). From day 5 through day 360 of follow-up, the difference in atrial pacing thresholds was highly significant (P < 0.01). with a smaller peaking of early thresholds and a much lower scattering of data for the steroid screw-in leads than for controls. Chronic thresholds as measured 1 year postimplant in terms of minimum charge delivered for capture were 0.20 ± 0.03 μC in group I versus 0.54 ± 0.11 μC in group II (P < 0.01). There was no difference between groups on the ventricular level, both acutely and during follow-up. If the active fixation atrial lead was compared to its tined ventricular counterpart in group I, pacing thresholds only differed within the early days postimplant, but they were virtually identical from week 3 through 1 year. It is concluded that the novel pacing lead design effectively combines low energy pacing with more versatility in electrode positioning by use of the active fixation mechanism.