Introducing the Evident™ MWA System

Clinical studies have shown that simultaneous use of multiple Evident™ MWA antennas may result in a high rate of ablative technical success and possible reduction of local recurrence.^1,2

The Evident™ MWA System demonstrates improved versatility and procedural efficiency over radiofrequency ablation systems. Features include:

Minimized set up.
When using the Evident™ MWA Surgical Antenna, system set up is a three-step procedure: Connect the antenna to the generator, set power and set time.
Simultaneous antenna use.
Simultaneous activation of multiple Evident™ MWA antennas allows for a more time-efficient procedure, especially in patients with multiple lesions, compared to other ablation techniques, such as cryoablation and RFA.¹
Multiple-use antennas.
Evident™ MWA antennas are versatile, and can be used for hepatic tumor ablation, coagulation of tissue prior to resection, or both, all with Covidien ablation technology.

Microwave ablation (MWA) uses an electromagnetic field to agitate water molecules in tissues and subsequently elevate tissue temperature. The resulting heat induces cellular death via coagulation necrosis.

The Evident™ MWA System, which uses electromagnetic waves operating at a frequency of 915 megahertz (MHz), can create ablations within 10 minutes at 45 watts of power (W), with the application of one antenna, or two or three antennas simultaneously. The system can produce individual lesions at each antenna, or one combined lesion when the antennas are spaced 1.5 cm to 2 cm apart.

Microwave ablation differs from radiofrequency ablation is some important ways. With microwave ablation, there is no flow of current through the patient. Instead, the MWA antenna radiates a uniform field of electromagnetic energy into the surrounding tissue, creating a zone of ablation. So there is no need for a patient return electrode pad. Furthermore, microwave energy is less susceptible than radiofrequency energy to interference from various tissue properties, including initial radiofrequency impedance, perfusion, and temperature elevation.

Evident™ MWA System antennas are matched to tissue; they deliver energy only when the device is in tissue. Ablation is achieved by inserting the entire radiating section of the antenna into the target tissue and turning on the power. The system automatically shuts off when the set ablation time is reached. Image guidance is used to verify that the ablation zone has been achieved.

1. Martin RC, Scoggins CR, McMasters KM. Safety and efficacy of microwave ablation of hepatic tumors: a prospective review of a 5-year experience. Ann Surg Oncol. August 26, 2009. [Epub ahead of print]

2. Iannitti DA, Martin RC, Simon CJ, et al. Hepatic tumor ablation with clustered microwave antennae: the US Phase II Trial. HPB (Oxford). 2007;9(2):120-124.