Effects of mexiletine, propafenone and flecainide on signal-averaged electrocardiogram

The effects of mexiletine, propafenone and flecainide on the parameters of signal-averaged electrocardiogram in 40 subjects with symptomatic and repetitive ventricular arrhythmias were studied. Mexiletine (n=16) suppressed ventricular arrhythmias in 10 patients and did not produce any significant changes in filtered QRS duration (fQRS), root mean square voltage of the final 40 ms of filtered QRS (RMS40) or low amplitude terminal component duration (LAS40). Acute (n=8, 450 mg) and chronic (n=16, 600-1200 mg . day-1) administration of propafenone determined a significant increase in fQRS (from 123\ub12.2 to 139\ub13 ms) and a reduction in RMS40 (from 54\ub18.8 to 34\ub16.7 \u3bcV); as a consequence the incidence of ventricular late potentials rose from 43 to 62%. The observed effects were independent of anti-arrhythmic efficacy, which was 86% for this drug. Acute (n=8, 200 mg) and chronic (n=13, 200-300 mg . day-1) administration of flecainide was associated with a marked prolongation in fQRS (from 123\ub12.8 to 138 \ub14.1 ms) and a reduction in RMS40 (from 69\ub111.5 to 47\ub111 \u3bcV); thus determining an increase in the incidence of ventricular late potentials from 29 to 48%. Changes in signal-averaged electrocardiogram were not related to drug efficacy, which was 81%. These data indicate that 1c anti-arrhythmic drugs consistently modified the parameters of signal-averaged electrocardiogram; the observed changes might reflect an inhomogeneous slowing of intramyocardial impulse propagation

ENVIRONMENTAL SERVICES ASSOCIATED WITH THE RECLAMATION OF AREAS DEGRADED BY MINING: POTENTIAL FOR PAYMENTS FOR ENVIRONMENTAL SERVICES

Abstract This paper discusses the potential of associating environmental services (ES) with techniques for reclaiming degraded areas (RDA) used in the mining sector, considering the current trends in payments for environmental services (PES) in Brazil. A literature review with content analysis generated results which identified the ES generated for eight cases of RDA in mining. As an example, ES related to soil enhancement were found. A more extended review of general RDA techniques confirmed the potential for associating other ES to RDA techniques used in mining, an example here is the enhancement of carbon stocks. Support for actions could come from existing PES schemes, particularly for cases where the ES identified as associated with an RDA technique are related to soil and water conservation. Concluding remarks indicate that there is a potential scenario for ES diversification in the reclamation stage of mining operations. A first step towards accomplishing this diversification envisages the creation of a PES scheme specific to the mining sector. Further studies are needed to develop criteria for fostering a PES scheme specifically for the reclamation phase of mining operations in Brazil