Electrovaporization using a rollerball electrode for flat or small papillary tumors of the bladder: basic study in dogs.
OBJECTIVE
We investigated electrovaporization of flat bladder tumors with a rollerball electrode 3 mm in diameter as a substitute for conventional transurethral resection with a cutting loop.


METHODS
A basic study of the action of electrovaporization was performed in dogs. The bladder was exposed under general anesthesia in three mongrel dogs. The rollerball electrode was attached to the resectoscope and inserted into the bladder via a cystostomy. Then electrovaporization was performed with a low or high pressure on the electrode tip and a speed of about 1 cm/sec using a Force 40 generator. The cutting mode power was set at 100 W or 200 W. The effects of the rollerball and cutting loop electrodes were also examined in the coagulation mode (45 W) as a control.


RESULTS
A deeper vaporization zone was obtained by using a power of 200 W in the cutting mode than with a power of 100 W, and a desiccation zone was found below the vaporization zone (VZ). The VZ was thicker with a high contact pressure than with a low contact pressure. This VZ was deeper than the tissue defect and heat-affected zone obtained using a rollerball electrode or cutting loop electrode in the 45 W coagulation mode.


CONCLUSIONS
Although caution is required because the VZ can become too deep with excessive pressure, the rollerball electrode seems to be safer and more useful than the cutting loop electrode for resection of flat or small papillary bladder tumors.
Goya
N
N
Department of Urology, Tokyo Women's Medical University, Japan. goya@kc.twmij.ac.jp
Ishikawa
N
N
Tomizawa
Y
Y
Ryoji
O
O
Ito
F
F
Onitsuka
S
S
Yamaguchi
Y
Y
Toma
H
H
D000818:Animals; D003558:Cystoscopy; D003559:Cystostomy; D004285:Dogs; D004566:Electrodes; D004598:Electrosurgery / Q000295:instrumentation*; D004867:Equipment Design; D001743:Urinary Bladder / Q000473:pathology / Q000601:surgery; D001749:Urinary Bladder Neoplasms / Q000473:pathology / Q000601:surgery*; D014835:Volatilization