Radiofrequency device may help minimize bleeding during laparoscopic partial nephrectomy

May 1, 2008

Researchers have developed a novel technique of performing laparoscopic partial nephrectomy without renal hilar clamping that appears to minimize blood loss during the procedure.

The researchers, led by Ilia Zeltser, MD, a former fellow in minimally invasive/robotic surgery at UT Southwestern, utilized a device called a Habib 4X (AngioDynamics, Queensbury, NY), which is a laparoscopic focal radiofrequency-coagulation device (FRFC) used in liver resections to minimize blood loss. The device has four radiofrequency probes that can be inserted to a depth of 3 cm along the surgical plane. When high-energy radiofrequency waves are passed through the electrode, it leads to cellular heating, resulting in coagulation necrosis. Following FRFC coagulation, the parenchyma can be transected with cold scissors without the need for additional hemostatic maneuvers, explained Dr. Zeltser, a clinical assistant professor of urology at Thomas Jefferson University, Philadelphia, and attending urologist at the Bryn Mawr Urology Group, Rosemont, PA.

The Habib 4X, named after the British liver surgeon who invented it, is a novel device that has been used successfully in partial hepatectomies.

Five female pigs underwent 14 laparoscopic partial nephrectomies using the laparoscopic FRFC device without hilar clamping. In phase one, single or multiple segments of the lower, upper, or middle pole were resected following radiofrequency coagulation of the resection plane. Large entries in the collecting systems were repaired, while very small rents were left open. In phase two, following 2-week survival, a laparoscopic FRFC heminephrectomy without hilar clamping was performed on the contralateral renal unit utilizing the same technique. The animals were then euthanized, the kidneys were harvested and weighed, and an ex vivo retrograde pyelography was performed to assess the collecting system integrity of the renal units treated in phase one.

Success with no clamping

All 14 nephrectomies were performed successfully without hilar clamping or open conversion. The resected segments comprised 12% of the kidney in phase one and 35% in phase two. Mean estimated blood loss was 45cc in phase one and 76.5cc in phase two. Reconstruction of the collecting system was necessary following one resection in phase one. Retrograde pyelograms revealed urinary extravasation in two renal units, both of which did not undergo collecting system reconstruction. At harvest, no hematomas or perinephric collections were observed. Histologic examination of the resection margin revealed hemorrhage and acute and chronic inflammation, with some hyalinization of the proximal and distal tubules, and with none extending deeper than 3 mm.

The primary goal of treatment of small renal masses is complete destruction of malignant tissue while maintaining maximum renal function and minimizing morbidity. Although ablative techniques have recently been popularized, the long-term outcome of these technologies is largely unknown. Surgical extirpation remains the treatment of choice for younger patients with small renal masses. However, there is growing body of evidence from patients with solitary kidneys who underwent partial nephrectomy that showed a limited period of warm and even cold ischemia is associated with higher risk of acute renal failure and chronic renal insufficiency.

Of note, other hemostatic devices, such as the potassium-titanyl-phosphate laser (GreenLight, Laserscope, San Jose, CA) and water jet high-density monopolar saline-cooled radiofrequency device (TissueLink FB3.0, Salient Surgical Technologies, Dover, NH) have also been utilized to perform partial nephrectomy without hilar clamping in both animal and clinical studies.

The researchers advise caution in extrapolating their results to a clinical setting. Although they attempted to raise the animals' blood pressure during resections, the achieved mean arterial pressure values were significantly lower than those seen in humans. Even at lower pressure, bleeding from large arterial branches during large resections in phase two was somewhat difficult to control and required several cycles of coagulation.

"Where the FRFC-assisted resection of small exophytic tumors without hilar occlusion appears feasible, arterial bleeding during sleep resections would be difficult to control with the FRFC alone and hilar clamping is necessary, albeit only for a short time, Dr. Zeltser said. "Although the FRFC may not be the final answer to a non-ischemic laparoscopic partial nephrectomy, it holds great promise in significantly limiting the duration of warm renal ischemia."

The device also doesn't seem to seal the collecting system, as shown by contrast extravasation on ex vivo retrograde pyelograms in two animals. Similar outcomes are seen in clinical studies where tumors were managed by radiofrequency ablation alone. Radiofrequency coagulation of the collecting system probably should be avoided in order to maintain healthy vascularized tissue, which can be reconstructed.

During the discussion, the researchers mentioned that a modification of this device will be released soon. The device will have an articulating tip with only two probes, and thus will have the potential to form a thinner zone of coagulation, preventing unnecessary coagulation of normal renal parenchyma.

Session moderator Louis Kavoussi, MD, Long Island Jewish Medical Center, New Hyde Park, NY, raised concern about the cost of the device. The cost of using this disposable device was $3,000 per case, which significantly adds to the cost of the procedure, he noted.