ARCHIVED - NRC Spin-Off Novadaq Receives FDA Approval for Surgical Device

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April 05, 2005— Ottawa, Ontario

Imagine a cardiac surgeon watching the blood flow through their patient's heart and arteries during coronary artery bypass surgery. Are there any leaks or blockages in blood flow? No problem; it's just a quick fix while the patient is on the operating table.

SPY Intra-operative device: imaging system with laser light on an ambiguating arm. Can be sterilized and swung over the patient when the surgeon needs to visualize and photograph the graft
SPY Intra-operative device: imaging system with laser light on an ambiguating arm. Can be sterilized and swung over the patient when the surgeon needs to visualize and photograph the graft

Thanks to Novadaq, a privately held Canadian company spun off from the National Research Council, this scenario will soon become routine. Novadaq Inc. has just received FDA (U.S. Food and Drug Administration) approval to market its SPY Intra-operative Imaging system for coronary artery bypass graft (CABG) surgery in the United States. This technology is already in use in Canada, Japan and Europe.

Coronary artery bypass graft surgery uses arteries from other parts of the patient's body to substitute for clogged heart arteries. According to the American Heart Association, there are approximately 400,000 CABG surgeries are performed annually in the US, half of the worldwide total. In comparison, Canadians underwent nearly 25,000 CABG surgeries in 2000.

These numbers are expected to rise, however, as 40 percent of Canadians will develop some form of heart disease or stroke over their lifetime. Cardiovascular disease and stroke currently cause one in three deaths, according to the Heart and Stroke Foundation of Canada.

FDA approval allows Novadaq to sell the SPY Imaging system to the world's largest market and establishes the company in the international medical diagnostics industry.

"We had focused on developing the clinical value of this technology in 'visionary centres' like the Sunnybrook Health Centre in Toronto, which has used this technology for several years." said Mary Kay Baggs, Novadaq's Vice President of Cardiac Sales and Marketing. "Now that we have regulatory clearance, we will be building our sales organization to grow our presence in North America and Europe."

"This technology is the easiest and safest method available to check for graft failure after coronary artery bypass surgery," said Baggs. Bad grafts occur in approximately five percent of surgeries and can cause myocardial infarction, bleeding and sometimes death.

As a Research Officer at the NRC Institute for Biodiagnostics (NRC-IBD), Dr. John Docherty, along with his graduate student, Rick Mangat, developed the SPY Imaging system's core technology. They discovered that a laser light could track the progress of a harmless dye called indocyanine green (ICG) though the body's circulatory system (see photo). The ICG is administered to the patient through an existing venous access line and binds to blood (binding is temporary), which allows tracking. Because such a high percentage of grafts fail, various imaging methods have been developed to diagnose graft potency intraoperatively, or while the patient is still on the table. None of these methods, however, have been universally adopted in practice.

X-ray angiography is the 'gold standard' approach to check for graft failure. It involves taking an X-ray of the patient's heart to visualize blood flow after grafting. It's not routinely used, however, because the equipment is rarely available in operating rooms and the procedure requires radiation safety measures and increases operating time.

Heart with ICG illuminated and photographed by the SPY Imaging system
Heart with ICG illuminated and photographed by the SPY Imaging system

Doppler echocardiography uses an ultrasound probe applied directly to the surface of the heart to visualize the graft using ultrasound images. The ultrasound probe comes equipped with a microphone that measures the blood's velocity, which tells the surgeon whether the blood is flowing properly through the grafted vessel.

The size of the probe and the short range of the ultrasound waves make it difficult to assess hard-to-reach repairs. In addition, tissue calcification, lesions or particularly twisted blood vessels can obscure the image.

Transit-time flowmetry (TTFM) measures blood flow by passing ultrasonic signals through the grafted blood vessel. The signal is sent out from a transducer located above the artery and is bounced off an acoustic reflector below the artery back up to a second transducer.

Although TTFM is very sensitive, it sometimes over-estimates graft failure, especially when blood flow is sluggish. One research paper suggests that the combination of TTFM and Novadaq's SPY imaging system would give surgeons the most complete intraoperative picture of graft potency.

Dr Docherty left the NRC in November 2000 to pursue a prototype of the SPY technology. They obtained their first regulatory approvals in Canada and Europe in 2001. Dr. Docherty continues to play an advisory role for Novadaq, while his former graduate student, Dr. Mangat, is now VP of Operations.

Cardiac surgery is just the beginning for Novadaq's SPY technology, which can be used to track the flow of blood anywhere in the body. According to Baggs, the company is licensing technology from Johns Hopkins University which will allow the SPY system to be used to diagnose and treat patients with age-related macular degeneration (AMD).

Other applications on the horizon for the SPY Imaging system include treating diabetic retinopathy, another prevalent eye condition, and monitoring organ transplant surgeries. Novadaq plans to seek regulatory approval for these applications as their company grows.

Dr Ian Smith, Director General of the NRC-IBD, puts Novadaq's accomplishments in a national context.

"The success of Novadaq is a superb demonstration of success on the difficult path from bench to bedside. Hundreds of cardiac bypass surgeries have been guaranteed by this simple procedure. Novadaq shows the world that Canada can do it too!"

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