Ultrasound for Cutting and Coagulating Tissue:

Comparison of linear and torsional mode ultrasonic coagulating shears for the sealing of medium- to large-sized arteries

BACKGROUND

Torsional mode ultrasonic coagulating shears have recently been developed for endoscopic and conventional surgery. The current investigation was conducted to compare the effectiveness of this device with the more established linear mode shears for the sealing of medium- to large-sized arteries.

METHODS

Porcine carotid arteries were prepared in vitro. Each vessel was coagulated and cut by both torsional and longitudinal mode devices at different sites. The burst pressure of each seal was then measured by placing a catheter secured with a ligature into the open end of the vessel. The catheter was connected to a pressure transducer and saline was gradually infused until there was leakage from the sealed end. The acute burst pressure was defined as the peak pressure recorded. Statistical differences were evaluated by Mann-Whitney U test.

RESULTS

A total of 104 seals were made on 50 vessels, 52 with each device. Median burst pressures for arteries 3.3-4.2 mm and 4.3-5.2 mm in diameter were 321 and 354 mmHg for torsional mode shears compared with 479 and 317 mmHg for linear mode shears (p = 0.193 and 0.579, respectively). For larger arteries (5.3-7.4 mm in diameter), the torsional mode shears achieved significantly higher seal strength than the linear mode shears (median burst pressure = 378 vs. 203 mmHg, p = 0.027). There was no significant correlation between the burst pressure and the vessel size for the torsional mode device (r = -0.109, p = 0.441). However, the burst pressure was adversely affected by increased vessel size for the linear mode device (r = -0.552, p = 0.000).

CONCLUSIONS

Both torsional and linear mode ultrasonic shears achieved secure hemostasis on vessels up to 5.2 mm. The torsional mode shears had the extended ability to coagulate larger-sized vessels up to 7.4 mm with the same degree of confidence.