Safer surgery for aging hearts:
Dr. Stacy O’Blenes tests new ways to protect fragile hearts during surgery
Cardiac surgeon Dr. Stacy O'Blenes and his colleagues want to provide better protection to the heart muscles of both babies and older people undergoing heart surgery. Minimizing the damage that occurs during the operation could dramatically improve the success of heart surgeries later in life.
Heart cells die during surgery because the muscle must be made to stop beating for the surgeon to be able to operate. This is done by infusing the heart with 'cardioplegic' solutions containing potassium and other electrolytes to relax the muscle. "This means there is no blood, no oxygen, and no removal of calcium in the heart during surgery," says Dr. O'Blenes, an associate professsor in the departments of Surgery and Physiology & Biophysics at Dalhousie Medical School. "This combination of factors kills heart cells and can damage the beating mechanism."
The hearts of young babies and of elderly people are most vulnerable to injury in this chemically induced state of rest. While special cardioplegic solutions have been developed for babies, the solutions used in adults do not vary to take the potential frailty of an older person's heart into account.
"The hearts of people in their 50s and 60s can handle the standard adult cardioplegic solutions, but the hearts of people in their 70s and 80s are most susceptible to damage," says Dr. O'Blenes, who operates on children and adults. "We think the solutions that work so well for babies could be adapted to provide better protection for older people during heart surgery."
Dr. O’Blenes and surgical colleague Dr. Camille Hancock Friesen are working with heart researcher Dr. Susan Howlett to test the pediatric solutions in the models of old heart cells in the lab. "We will continually refine and test the solution in the cell models until we find the formulations that provide optimal protection," he says, "then we can test the solutions in humans, using sophisticated catheter equiment purchased through the proceeds of the Molly Appeal."