Neither ePTFE nor BP is resorbable. Both materials have been used successfully, without resultant infections, for clinical staple-line reinforcement. The more favorable tissue response to ePTFE observed in this study may have clinical ramifications. Comparative clinical studies of the two materials are needed.
Summary:The development of catheter ablation techniques for therapy of cardiac arrhythmias continues to evolve. Although many patients have benefited from catheter ablation procedures. failure to ablate the anhythmogcnic substrate and complications from the pulse used in these procedures remain too frequent occurrences. The pu'pose of this review is to focus on these problems of inefficacy and safety with attention directed to the role various direct current and radiofrequency pulses have had in the genesis of these difficulties.
The purpose of this investigation was to examine in vivo the relationship of radio-frequency (RF) pulse voltage and duration on the volume of tissue injury. RF 500-kHz pulses of 20-, 40-, and 60-V amplitude (RMS) were applied to the epicardium of 18 dogs for pulsing periods of 5-20 s. Systematic and quantitative tissue analysis was then performed after 30 days. No chronic lesions were evident on microscopic examination for 20-V RF pulse applications up to 15 s. Application of 20-V pulses for 20 s produced small lesions having a volume of 2.4 +/- 0.7 mm3. At 40 V, the volume of tissue injury ranged from 39.1 +/- 10.3 mm3 for 5 s of pulse application to 128.8 +/- 24.8 mm3 for 20 s of pulse application. Over the first 15 s of 40-V pulse application, the volume of tissue injury increased as pulse application time increased. There was no further increase in tissue injury for 40-V pulsing durations greater than 15 s. At 60 V, volumes of tissue injury ranged from 122.7 +/- 33.5 mm3 at 5 s to 313.6 +/- 73.7 mm3 at 20 s. Lesion size increased significantly for pulse durations of up to 10 s. Thereafter, 60-V pulses yielded little increase in tissue injury. In addition, persistent 60-V pulsing for periods greater than 9 s duration resulted in arcing and tissue vaporization in 28% of the applications. Thus RF energy is limited in its ability to create safe and effective tissue injury.(ABSTRACT TRUNCATED AT 250 WORDS)
Multiple paired lesions produced by a train of high-voltage low-charge rectangular pulses (20 A, 30 microsecond) and a train of low-voltage high-charge rectangular pulses (2 A, 300 microsecond) were made to the left ventricular epicardium of 23 dogs to determine the relative influence of voltage and charge delivery on injury of canine myocardium. Both pulsing methods contained equal amounts of energy (15 J) delivered over equal periods of time (100 ms), and both pulsing methods were nonarcing and therefore nonbarotraumatic. The volume of cardiac tissue injury resulting from both types of pulses was then evaluated from planimetered serial histological sections after 1, 10, and 30 days. Over the 30-day period, lesion size progressively decreased to 56% of its original value for the high-voltage low-charge pulse. In contrast, lesion size from the low-voltage high-charge pulse remained relatively constant, decreasing only 12% of its original value. These results indicate that when energy delivery is held constant, voltage, not charge, is the dominant mediator of cell injury. Also, cells subjected to high voltages appear to recover partially over time with significantly less constancy of tissue injury than that seen with low-voltage high-charge pulses.
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