Device may increase flexibility of surgical lasers

September 16, 2013

Researchers say they’re seeing positive results in early analysis of an adaptive optical element they have developed to increase the flexibility of surgical lasers in the treatment of upper urinary tract disorders.

Pittsburgh-Researchers say they’re seeing positive results in early analysis of an adaptive optical element they have developed to increase the flexibility of surgical lasers in the treatment of upper urinary tract disorders.

“The element allows us to deliver laser energy through the existing optics of a ureteroscope and control the shape, size, and direction of the energy as it exits the scope,” said senior author Tatum Tarin, MD, assistant professor of urology at the University of Pittsburgh School of Medicine, in an interview with Urology Times. “The laser beam can be rapidly steered within the entire field of view of the endoscope without ever moving the tip of the endoscope during surgery, thus enhancing surgical accuracy, precision, and speed. This platform technology can be utilized with any procedure that utilizes a fiberoptic scope.”

At issue is the use of endoscopic surgery via ureteroscopy to treat conditions such as kidney stones, strictures, and some upper tract urothelial cancers.

“Advances in ureteroscope technology have allowed urologists to access the upper urinary collecting system and avoid making large incisions to access these structures,” said Dr. Tarin, who presented his group’s findings at the AUA annual meeting in San Diego.

The good news is that this kind of surgery has made a major difference in morbidity. But there are limits.

“Due to anatomic size constraints, ureteroscopes are very long and of a very small diameter-2-3 mm,” Dr. Tarin said. “Within this small scope, there must be mechanics to deflect the scope, optics, light source, and a working channel. Through the working channel, irrigation must flow so we can see within the collecting system. Without irrigation, we would lose all visibility and surgery would not be possible.”

The problem comes in the working channel, which is about 1 mm in diameter and must hold irrigation.

“This poses no problems when we are just performing diagnostic ureteroscopy,” Dr. Tarin said. “However, when we see a stone or tumor that we would like to intervene upon, we then must place a laser fiber down the working channel in order to deliver therapeutic energy to break the stones or ablate the tumor. This then occludes the working channel and severely diminishes the irrigant flow and thus visibility.

“Also, placing a laser fiber down the working channel decreases the ability to deflect the scope due to the inherent stiffness of the laser fiber.”

What does this mean in the big picture? In a procedure on a lower pole calyx tumor, for example, “The diseased portion of the kidney may not be able to be accessed or treated once a laser fiber is placed into the working channel,” he said.

Enter the adaptive optical element developed by Dr. Tarin and his colleagues. It allows the surgical laser source to be sent through the optical channel.

Approach completely opens working channel

“This approach completely opens the working channel, thereby eliminating problems associated with passing the laser fiber through the working channel,” Dr. Tarin said. “By sculpting the wave front of the laser, the on-target focal point, divergence, and on-target shape of the ablation laser spot can be actively controlled. The laser beam can be steered within the entire field of view of the endoscope without ever moving the tip of the endoscope during surgery.”

The research is still in its early stages, however. The authors used continuous green light laser on porcine renal parenchyma. Other experiments have used pulsed holmium laser.

“We are continuing work with additional benchtop testing to determine the amount of energy that can safely be delivered through existing ureteroscopes. Additionally, we are developing further enhancements to the technology, including motion tracking to improve safety and efficiency in the operating room,” Dr. Tarin said.

The device’s cost is unclear at this point. As for timing, Dr. Tarin said the technology could be available in 3 to 4 years.

Dr. Tarin said he has no financial stake in the device, but his institution does hold the intellectual property rights.UT

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