Catheter Based Endovascular Interventions
Mark Peterson
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At seven am on January 1st, a 17-year-old student riding a snowmobile was hit broadside
by a speeding minivan at a rural intersection north of Toronto. He suffered open
fractures, lacerations of the liver and spleen, and a minor head injury. His chest
X-ray and angiogram revealed a transected thoracic aorta just below the sub-clavian
artery. He was transferred for definitive treatment to St. Michael's Hospital. Mark
Peterson answered the call to assess this critically ill young patient.
Evidence has been accumulating recently that catheter based endovascular interventions
may reduce complications and offer advantages over open techniques (1) for traumatic
rupture of the aorta. This seemed an ideal case for a stent graft. Though large
size grafts used in older adult patients (eg. 26-40 millimetres in diameter by 200
millimetres in length) were available, a smaller graft was required to fit the slender
aorta of this young patient. The Cook representative in Montreal answered his cell
phone on the holiday, then promptly found and delivered a 22 X 115 millimetre graft.
The patient was treated with beta blockers for blood pressure control and sedation
until the graft could be placed, securing good apposition and a good result. Mark's
senior colleague Al Lossing, who has been doing endovascular procedures with radiologist
Andrew Common for the past ten years, had performed a similar intervention in a
traumatic rupture of the aorta in December.
Some trauma centres in the US have angio suites with full fluoroscopy and operating
room capability, a goal for St. Michael's within the next year. There is a problem
with reconciling the costs with current health care accounting practices. While
these devices and their ancillary costs actually save the healthcare system money
by sparing the patient a thoracotomy and cardiopulmonary bypass, the patient treated
with a percuntaneous stent uses a 12 thousand dollar device and 1.7 thousand dollars
of ancillary tools, but may be ready to go home in a few days without requiring
intensive care or prolonged hospitalization. (In trauma cases the need for intensive
care is related to the other associated injuries.)
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The new technology is being adopted slowly because of the high initial cost of the
devices. An innovation fund to finance these less predictable, but expensive offbudget
devices will eventually allow us to work out a way to incorporate them into the
standard annual budget.
Mark is married to Mala, a nephrologist. They have three children, Sachin, 3, Devin,
2 and newborn Uma. Mark is an active runner, squash and tennis player who grew up
in Winnipeg. His mother is from Florence, Italy, his father, a family doctor in
Winnipeg, served as the team physician to the Winnipeg Blue Bombers. Mark completed
medical school in Manitoba and came to Toronto for cardiac residency and a PhD in
immunology with Tom Waddell. He feels that the six-year cardiac program was appropriate
to the depth and breadth of knowledge required for the practice of cardiac surgery.
Mark studied with Ted Dietrich at the Arizona Heart Institute supported by his clinical
practice group and a grant from Terrence Donnelly. The Institute has four operating
rooms and performs 5000 percutaneous procedures per year. They have done more than
500 thoracic aortic stents. Mark was inspired by a talk given at St. Mike's by Ted
Dietrich, a surgical maverick, who established the Arizona Heart Institute 37 years
ago following his training with Michael Debakey and Denton Cooley. Mark works with
vascular radiologist Vikram Prabudesai. He is convinced that the specialty of cardiac
surgery has to evolve to "do more than hearts." While it may seem natural for him
to be working with a cardiologist, a fusion model has not yet been worked out with
that specialty. While at the Arizona Heart Institute, Mark performed abdominal,
renal and peripheral stenting as a full-service endovascular practitioner. In many
ways thoracic stents are the easiest to insert, based on the large size of the thoracic
aorta. Eventually cardiac valve surgery and particularly aortic stenosis will be
regularly approached using catheter techniques. At St. Michael's funds have been
allocated for 120 stents per year. This would last less than one month at the Arizona
Heart Institute. If the budget for health care were calculated on the basis of value
rather than cost, and the time axis for estimating the value of treatments extended
until health is restored, the case for innovations like endovascular stents and
their use in high volume centers would be transparently clear.
M.M.
1) Svensson LG, et al. Expert Consensus Document on the Treatment of Descending
Thoracic Aortic Disease Using Endovascular Stent-Grafts. Ann Thorac Surg 2008;85:S1-S41.
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