Example embodiments of the present invention include hot melt dental adhesive materials that can create a reversible bond. The inner sleeve comprises at least one external bulb with a surface which, in an unassembled, unloaded condition of the outer sleeve and the inner sleeve, is at a distance from the inner sleeve’s centre line which is greater than the outer sleeve’s internal radius. Because the instrument fixes the position of the tissue, and because the instruments remain at a constant distance from the particular portion of the heart where the surgery is being performed, the device may also serve as a support or platform so that other surgical instruments or devices can be advantageously used at the site. The list of measured cells comprises cells of the first frequency band, and cells of a second frequency band providing coverage both in the isolated area and in an area outside the isolated area.