Toronto (May 6, 2012) - In a North American first, vascular specialists at the Peter Munk Cardiac Centre used a new stent graft system to treat a patient with an abdominal aortic aneurysm. With this new device, patient wait times are reduced from months to weeks, the risk of complications is reduced and patients are able to come home earlier.
The patient, 72-year-old Harry Zegas of Toronto, was diagnosed with a five point eight centimetre (larger than a golf ball) abdominal aortic aneurysm – an outward bulging or ballooning of the large blood vessel supplying blood to the abdomen, pelvis and legs – in December 2011. An aneurysm can rupture and if it does, about 80-90 percent of individuals will die. After undergoing a five-hour procedure on March 1, Mr. Zegas was sent home less than a week later and is doing well.
"When my doctors told me, I was surprised. I knew I had issues with my blood pressure, but I wasn't in any pain," says Mr. Zegas.
Abdominal Aortic Aneurysms (AAA) are among the leading causes of death in Canada because they rarely show symptoms before they rupture and the person is often unaware of the problem until it is too late. About five percent or one in 20 male Canadians over 65 has an AAA, many of whom are former or current smokers, have high blood pressure or have a genetic predisposition to developing these aneurysms.
The device that Mr. Zegas received, known as the Fenestrated Anaconda, is the world's first fully repositionable stent graft system, meaning that it has technical advantages that allow surgeons greater freedom and accuracy when positioning the device inside the patient. Given that the abdominal aorta has vessels that feed blood to the kidneys, the stent graft must fit inside the aorta perfectly. Even millimetre (about the width of a hair) inaccuracies where the fenestrations, or punctures on each side of the device that allow blood to flow to the kidneys, are situated inside the body can result in kidney problems.
The device takes two to three weeks to manufacture, compared to two to three months for the older device that is currently being used at the Centre. Patient wait times are important because aneurysms can rupture while patients wait for surgery.
Each stent graft device is custom made for each patient. This device also comes with a plastic, life-size 3D model of each patient's aneurysm that is created based on their CT scan. This model allows surgeons to practice deploying a prototype of the device prior to surgery to iron out any problems ahead of time. In Mr. Zegas' case, Dr. Tse and the team were able to identify a hazard on one of their practice deployments prior to his surgery, and therefore avoid a serious complication.
"This is truly an example of personalized medicine. The 3D model allows visualization that is simply not possible on a 2D screen," says Dr. Leonard Tse, vascular surgeon at the Peter Munk Cardiac Centre and Assistant Professor of Surgery at the University of Toronto that performed the first procedure. Dr. Tse also holds a biomedical engineering degree from the University of Toronto, a degree he earned six years into his vascular surgery practice so that he could design stent grafts that can be used in emergency cases when AAAs rupture.
Endo-Vascular Aneurysm Repair (EVAR) is a minimally invasive procedure in which a vascular surgeon and interventional radiologist place a stent graft inside the aneurysm through two small incisions in the groin. The stent graft acts as conduit for the blood to flow through the artery rather than into the ballooned portion. The patient is usually sent home within two days. Since 2001, over 600 EVAR procedures have been performed at the Peter Munk Cardiac Centre with one of the lowest mortality rates in Canada, even in high risk patients.
"The 3D model allows vascular specialists to anticipate how the graft will deploy and sit inside the patient – something that previously only came with experience and intuition," says Dr. KT Tan, Chief of the Division of Vascular and Interventional Radiology, who is one of the most experienced radiologists with advanced endovascular stent grafts in Canada.
Special access from Health Canada allows PMCC to provide this device, as each is custom made for each patient. The fenestrated anaconda device has been used in about 80 patients in Europe.
About The Peter Munk Cardiac Centre
The Peter Munk Cardiac Centre is the premier cardiac centre in Canada. Since it opened in 1997, the Centre has saved and improved the lives of cardiac and vascular patients from around the world. Each year, approximately 17,000 patients receive innovative and compassionate care from multidisciplinary teams in the Peter Munk Cardiac Centre, and the Centre trains more cardiologists, cardiovascular surgeons and vascular surgeons than any hospital in Canada. The Centre is based at the Toronto General Hospital and the Toronto Western Hospital - members of University Health Network, which also includes Princess Margaret Hospital and the Toronto Rehabilitation Institute. All three sites are research hospitals affiliated with the University of Toronto. For more information, please visit http://www.uhn.ca/PMCC.
