Rapid-freezing transmural cardiac biopsy drill

We have built a transmural cardiac biopsy drill that uses an air turbine (10,000 rpm) to turn a stainless steel bore of either 2.0 or 4.5 mm diam. Vacuum draws the cut biopsies through the drill into isopentane chilled to -150 degrees C with liquid nitrogen. The steel bores cut through the beating canine left ventricular free wall in 0.14 +/- 0.04 (SD) permitting sampling in discrete portions of the cardiac cycle. Small and large biopsies traverse the drill in 0.48 +/- 0.19 and 0.15 +/- 0.04 s, respectively. Large biopsies freeze in 1.46 +/- 0.73 s, whereas small biopsies are calculated to freeze in 0.28 s. Average biopsy weights are 34 +/- 14 and 180 +/- 71 mg. Left ventricular myocardial blood flow measured with radionuclide-labeled microspheres showed that muscle plugs sutured into wound sites of 4.5-mm-diam biopsies cause a 30% reduction in myocardial blood flow within 0.5 cm of the biopsy site. Light microscopy shows normal cardiac muscle with little damage from drill rotation.