EndoSonics Submits IDE Application to the FDA for Directional Brachytherapy Device; Cleveland Clinic Foundation is Development Partner

Business Wire, March 28, 2000

Business Editors and Medical/Health Writers

RANCHO CORDOVA, Calif.--(BW HealthWire)--March 28, 2000

EndoSonics Corporation (Nasdaq: ESON), a leading developer and marketer of diagnostic assessment and therapeutic treatment devices, today announced that it has filed with the U.S. Food and Drug Administration (FDA) for an Investigational Device Exemption (IDE) to begin human clinical trials of its directional brachytherapy device to advance the treatment of cardiovascular disease.

EndoSonics has been developing the device, named BRIGADE(TM) -- Beta Radiation with IVUS Guidance And Directed Energy -- in conjunction with Drs. Jay P. Ciezki and E. Murat Tuzcu at the Cleveland Clinic Foundation (CCF). The Principal Investigator (PI) for the Phase I study will be Dr. Patrick Whitlow of the Cleveland Clinic. BRIGADE is designed to treat coronary arteries that have a high incidence of restenosis following successful intervention for cardiovascular disease. EndoSonics has two patents in the brachytherapy area, with other patents pending.

Strong Clinical Support for IVUS and Beta Radiation

In 1995, Drs. Jay P. Ciezki, E. Murat Tuzcu, and Urs O. Hafeli of the Cleveland Clinic determined that brachytherapy success was strongly correlated with delivering adequate dosage to the entire vessel wall. EndoSonics believes that angiography alone is insufficient to see the entire vessel structure, and that only through IVUS can physicians optimally direct radiation to the entire vessel wall.

The recently completed START trial demonstrated the efficacy of beta radiation for the treatment of coronary restenosis. Prior to this trial, gamma radiation showed clinical success in preventing restenosis. However, gamma energy is highly penetrating and exposes the patient and lab personnel to unnecessary radiation. Beta radiation has more limited penetrating power and is easily shielded, allowing for more active sources that keep treatment time to a minimum. This makes it more practical in a high volume cath lab and safer for both the patient and lab personnel. Beta radiation's primary disadvantage is its sharp dose drop off. With integrated IVUS, however, EndoSonics believes that the dosing can be targeted to offset this disadvantage.

IVUS also has shown promise for avoiding over-radiation of tissues, which the Cleveland Clinic researchers believe is responsible for causing tissue necrosis, which in turn leads to platelet aggregation and thrombosis. This complication can result in serious consequences such as myocardial infarction (MI) or death. Current practice to combat this late event is to prescribe anti-platelet therapy indefinitely. However, long term GLP animal studies performed at the Cleveland Clinic demonstrated that IVUS guided directional brachytherapy can guard against over radiation.

Reinhard Warnking, President and CEO of EndoSonics, said, "EndoSonics' all-digital IVUS technology gives us the distinct competitive advantage of being the only company that currently combines IVUS and therapeutic devices on a single catheter. With this approach, we believe we have demonstrated our ability to optimize treatment and improve clinical outcomes - with potential direct and obvious benefits to the patient and to the payor community. In addition, this approach reduces catheter exchanges, and should help to reduce total procedure time and improve physician and facility efficiency. We are excited about the potential of BRIGADE to continue this revolution in interventional medicine."

Dr. Patrick L. Whitlow, Director of Interventional Cardiology at the Cleveland Clinic and Principal Investigator for the Phase I study, said, "Because the majority of diseased coronary arteries are eccentric in shape, or the diseased tissue is eccentric with respect to the artery structure, current devices that emit radiation symmetrically risk under- or over-dosing the target tissue. Too little radiation results in no inhibition or increased intimal tissue growth while too much radiation can create unwanted damage. A Scripps Institute randomized trial of intravascular brachytherapy with IVUS guidance of symmetrical radiation to prevent in-stent restenosis demonstrated a 68.5% reduction of restenosis. We believe that the CCF/EndoSonics device will offer a system that permits easy and precise delivery of radiation, and may lead to improved results for our patients. Radiation dosing errors due to asymmetry of arterial wall plaque has contributed to the 15-25% failure rate of previous radiation devices, and this limitation should be solved with the design of this catheter."

EndoSonics Corporation, headquartered in Rancho Cordova, Calif., is a leading developer, manufacturer and marketer of intravascular ultrasound (IVUS) imaging products and functional assessment products to assist in the diagnosis and treatment of cardiovascular and peripheral vascular disease. Visit EndoSonics on the Internet at www.endosonics.com.

Except for the historical information contained herein, the matters discussed in this press release are forward-looking statements, the accuracy of which is necessarily subject to risks and uncertainties. Actual results may differ significantly from the discussion of such matters in the forward-looking statements. Factors that may cause such difference include, but are not limited to, delays by regulatory authorities, scientific advances by the company or third parties, the timely availability and acceptance of the company's new products, the impact of competitive products and pricing, dependence on key personnel, as well as those factors set forth in EndoSonics' Annual Report on Form 10K for the year ended December 31, 1998, Quarterly Report on Form 10-Q for the quarter ending September 30, 1999, and other filings with the Securities and Exchange Commission.