Development of a Permanently Controllable Rotating Biopsy Device, Part I: Theoretical Considerations and In-Vitro Results for Five Different Prototypes

Abstract

To develop different prototypes of permanently controllable rotating biopsy devices with determination of the most efficient prototype in biopsies in bovine myocardium. Five different prototypes of 18-gauge rotating biopsy devices were designed and constructed, four (1 - 4) with various drill-like cutting edges and one (5) cannula type with a lancet-like helically bent cutting edge. Using bovine myocardium as the biopsy tissue, n = 100 specimens per prototype were obtained, and a quantitative analysis including tissue fragmentation, length in mm and weight in mg was carried out. For statistical analysis, the chi-square test for tissue fragmentation and Kruskal-Wallis test for the parameters length and weight were calculated. Prototype 5 showed the highest rate of extraction of one-fragment specimens in n = 66 cases and the lowest rate of failure to obtain tissue in n = 11 cases. The mean length/weight were 4.15 mm/ 3.91 mg for prototype 1, 1.80 mm/ 1.66 mg for prototype 2, 4.61 mm/ 3.28 mg for prototype 3, 5.20 mm/ 3.74 mg for prototype 4, and 9.57 mm/ 6.97 mg for prototype 5. In all three categories, prototype 5 was significantly superior to the prototypes 1 - 4 with p < 0.001. The cannula type with a lancet-like helically bent cutting edge proved to be the most efficient prototype and may now be tested competitively against established automated biopsy devices in vitro.