 Dr. Oren Steinmetz, MUHC chief of service, Division of Vascular Surgery, is a visionary in his field, seeing endovascular surgery as a rapidly evolving area with huge potential when the MUHC Division of Vascular Surgery first started in 1997. (Photo: Pierre Dubois) |
They cause no symptoms until they burst. When they do, they are deadly. Ruptures of abdominal aortic aneurysms are the fifth leading cause of death for males over 65. Until a few years ago, preventing ruptures required major, high-risk surgery, which took weeks of recovery. Now, thanks to new techniques, aortic aneurysms can be treated using far less invasive surgery.
The abdominal aorta is the portion of the aorta - the largest artery in the body - that passes through the stomach area. Sometimes, the abdominal aorta develops an aneurysm - a weakness in the wall of the blood vessel. As the aneurysm enlarges, it balloons out, weakening the vessel wall. If the aneurysm ruptures, the result is death in about 90 per cent of cases.
Before aortic aneurysms rupture they are asymptomatic, explains Dr. Oren Steinmetz, MUHC chief of service, Division of Vascular Surgery. "We discover them while doing a physical exam or a diagnostic test like a CT scan - usually while looking for something else," he explains. "When we do, we have three options: do nothing, perform traditional surgery, or use our new endovascular techniques to insert a prosthetic device directly into the artery to strengthen it."
While the traditional procedure for repairing aneurysms is well established, it requires major surgery, and is often too risky for elderly patients or those compromised by some underlying condition such as heart disease.
"The new endovascular technique is less invasive and the strategy behind it is different," says Steinmetz. "In effect, we insert a new 'pipe' inside the old 'pipe.' The aneurysm is still there but blood flow is directed through a prosthesis, a tiny fabric tube supported by a metal frame. This takes the pressure off the wall of the aorta and decreases the chances of it rupturing."
To insert the prosthesis, surgeons thread catheters and guide wires through a small incision in a blood vessel in the groin and guide it into position in the aorta, using advanced imaging techniques such as fluoroscopy to position it correctly. Once the catheter is in exactly the right position, the prosthesis is deployed. The procedure takes between two and three hours. Pioneered by a South American surgeon in the early 1990s, it was first performed at the MUHC in 1997.
"This technique has several advantages," explains Steinmetz. "We can do the procedure under local or spinal anaesthetic, with far less surgical trauma for the patient. Post-op hospital stays are generally two or three days, instead of seven to 10 days with the traditional procedure. Most patients don't require a stay in the ICU, and the short-term risk of death after surgery is about one third of that seen with the traditional procedure."
Patients from the MUHC as well as other Montreal and regional hospitals are referred through the MUHC's division of Vascular Surgery, and evaluated to see if they are suitable candidates. The McGill program for endovascular surgery for aneurysms is a combined program, delivered through both the Royal Victoria Hospital of the MUHC and the Montreal Jewish General Hospital. The program is one of the largest in Canada. Since its inception in 1997, surgeons have repaired nearly 500 aneurysms using the endovascular procedure.
While endovascular aortic aneurysm repair has proved extremely successful, Steinmetz cautions that it is not for everyone. "Patients need to be monitored carefully for the rest of their lives, with CT scans and ultrasound," he says. "The procedure doesn't 'cure' the underlying condition. The aneurysm is still there, and it still has to be watched carefully."
Steinmetz and his colleagues are currently comparing the efficacy of the new and traditional procedures in treating people with ruptured aneurysms. They are also studying the possibility of implanting pressure sensors inside the aorta, to monitor pressure within the aneurysms themselves.
A vascular surgeon, Steinmetz saw endovascular surgery as a rapidly evolving area with huge potential when the MUHC program started. Developments in the last few years have proved him correct. The field continues to evolve at a rapid rate, with new technology and materials opening up novel possibilities. "Techniques have really changed in some areas as endovascular surgery has evolved," says Steinmetz. "It's an exciting, dynamic area."
 Dr. Oren Steinmetz uses an endovascular technique to repair aortic aneurysms. During this non-invasive surgery a tiny fabric tube supported by a metal frame is inserted into the aorta, taking the pressure off the wall of the aorta and decreasing the chances of it rupturing. (Photo: Pierre Dubois) |