Author + information
- Received November 24, 1986
- Revision received March 17, 1987
- Accepted April 20, 1987
- Published online September 1, 1987.
- Herbert J. Geschwind, MD, FACC*,1,
- Morton J. Kern, MD, FACC1,
- Michel G. Vandormael, MD, FACC1,
- John D. Blair, MD1,
- Ubeydullah Deligonul, MD1 and
- Harold L. Kennedy, MD, FACC1
- ↵*Address for reprints: Herbert J. Geschwind. MD, Division of Cardiology, St. Louis University Medical Center, 1325 South Grand Boulevard, St. Louis, Missouri 63104.
To evaluate the safety and efficiency of optically modified fiber tips, craters were created in human cadaver atherosclerotic arterial walls using sapphire contact probes and lensed fibers connected to a continuous wave neodymium yttrium aluminum garnet (Nd-YAG) laser. Laser energy was emitted at a constant level of 50 J. The sapphire contact probe catheter consisted of a round 2.2 mm diameter synthetic sapphire attached to an 8F catheter into which a 0.2 mm diameter optical fiber was inserted with the distal tip maintained at 3 mm from the sapphire. The lensed fiber catheter consisted of a 0.2 mm optical fiber at the end of which a 1 mm diameter lens was made. The fiber was inserted into a 5F low profile balloon catheter with the lens maintained 3 mm beyond the catheter tip. During laser emissions the catheter tips were maintained in a stationary position in contact with tissue targets immersed in blood at an angle of 90°.
The diameter of holes at the entry and exit of craters, the depth of craters and thermal injury to adjacent tissue (rim of carbonization and vacuolization) were measured with microscopy. The volume of tissue removed was derived from these values. Controlled effect index was determined as the ratio of diameter of holes and the extent of thermal injury. Efficiency was determined as the ratio of volume of tissue removed and the energy required to vaporize tissue. The results were compared with those obtained with 0.2 mm bare fibers using the same energy. Efficiency for lensed and sapphire catheters was 0.04 ± 0.1 and 0.11 ± 0.2 mm3/J, respectively, as compared with 0.01 ± 0.02 mm3/J for bare fibers (p < 0.001). Controlled effect index for lensed and sapphire catheters was 5.8 ± 0.7 and 8.8 ± 1.7, respectively, as compared with 2.1 ± 0.4 for bare fibers (p < 0.001).
In conclusion: 1) Optically modified fiber tips appear to enhance the safety and efficiency of laser tissue ablation for potential arterial recanalization. 2) Both the efficiency and the safety of sapphire contact probe catheters are greater than those of lensed fiber catheters.
- Received November 24, 1986.
- Revision received March 17, 1987.
- Accepted April 20, 1987.
- American College of Cardiology Foundation