Technology

Ultrasound is a well-known energy source for hyperthermia treatments of various malignancies (REF- Diederich and Hyynen, 1999), since energy direction and distribution in the tissue can be controlled by means of intensity, duration and frequency. The ultrasonic energy is absorbed in the soft tissue, results in local heating, and the target tissue is thermally damaged. For example, high-intensity focused ultrasound (HIFU) is used for non-invasive tissue ablation of uterine fibroids (REF), prostate cancer and other pathologies.

Low-intensity ultrasound is used for imaging, with negligible effects in tissue. IntraVascular Ultrasound (IVUS) catheters are used for imaging the inside of blood vessels, for example, for identifying plaques or narrowing.



Ultrasound is an ideal energy source for renal denervation, as it can ablate renal nerves within 0.5-10mm from the lumen, while keeping artery wall intact.

The TIVUS™ System is intended to reduce blood pressure in patients with treatment-resistant hypertension by delivering ultrasonic energy through the wall of the renal artery; thus, reducing excessive sympathetic nervous system activation.

The TIVUS™ System uses high-frequency, high-intensity directional ultrasound. The ability of controlling the ultrasonic energy distribution and the tissue heating pattern through treatment parameters (frequency, intensity and duration) enables to specifically target the sympathetic nerves while maintaining the renal artery wall integrity (See below damaged nerves’ distribution of both RF and Ultrasound technologies, as performed in swine model) . Moreover, undisturbed blood flow between the catheter and the artery wall further enables efficient cooling of the catheter, as can be seen in the pictures below.

 

* RF vs Ultrasound technology – Energy distribution and affected nerves

* Unidirectional TIVUS™ catheter – Procedure simulation

Cardiosonic developed various designs of catheter for multiple uses in order to address different requirements. The first generation was a unidirectional TIVUS™ catheter, the second generation was a unidirectional TIVUS™ catheter with steering capabilities, while the third generation, and the most advanced one, is the Multidirectional TIVUS™ catheter.

 

The Multidirectional TIVUS™ Catheter is a 6F catheter, with a usable length of 645mm. It is powered by the TIVUS™ Console. The Multidirectional TIVUS™ Catheter is composed of three ultrasonic elements. The triangular design enables simultaneous ultrasound emission which results in localized circumferential treatment, and thus facilitates and shortens the renal denervation procedure.

Positioning the multidirectional TIVUS™ catheter in the center of the renal artery is achieved using a three-petal-shaped distancing device, which is opened and closed using a lever at the catheter handle.

The TIVUS™ Catheter has a radiopaque tip that assists in the positioning of the catheter using fluoroscopic guidance. Moreover, the catheter's transducer indicates the distance from the artery wall. Thermistors indicate the average temperature of the blood flowing over each of the ultrasonic elements during procedure. Safety control feedback is displayed on the screen


 

The main advantages of TIVUS™ non-focused ultrasound in comparison to radiofrequency-based technology are:

  • The TIVUS™ US-based technology does not require direct contact with artery wall
  • Non-occlusive catheter
  • The TIVUS™ technology maintain artery wall integrity
  • Energy parameters are stable during treatment
  • Renal nerves are blocked with minimal damage to other tissues