Using blood-pressure cuff in new way could limit heart attack damage: study
TORONTO (CP) — Virtually everyone has had their blood pressure measured with a pumped-up cuff encircling their upper arm. But it turns out that this commonplace medical device could one day have another critical use — reducing the amount of damage from a heart attack, researchers say.
In a study of more than 250 Danish adults experiencing a heart attack, Canadian-led scientists used a blood pressure cuff to intermittently stop blood flow in the arm, a process that begins while a patient is being transported to hospital by ambulance.
Called “remote ischemic preconditioning,” the procedure developed by Toronto’s Hospital for Sick Children was found to significantly limit the amount of damage to the heart muscle caused by a blockage in a cardiac blood vessel.
Ischemic preconditioning involves using the device to interrupt blood flow in the arm, off and on over a period of 35 to 40 minutes: the cuff is inflated for five minutes, then deflated for five minutes, with the procedure being repeated consecutively four times.
Once at the hospital, the patient receives routine heart attack treatment, including cardiac angioplasty. Preconditioning using the cuff may still be going on throughout this procedure, which uses a tiny inflatable balloon to open up narrowed or blocked blood vessels to the heart.
Researchers, whose paper appears in today’s issue of The Lancet, found that those heart attack patients randomly assigned to have preconditioning had an overall reduction in heart muscle damage of 30 per cent, compared to those not treated with the cuff.
In those having the largest, typically most devastating, heart attacks, the amount of damage was cut by about 50 per cent, said senior co-author Dr. Andrew Redington, head of cardiology at Sick Kids Hospital.
“And we know, of course, that the bigger the heart attack you have, the more likely you are to die and the more likely you are to have subsequent symptoms of heart failure and all the bad things that having a heart attack predicts,” Redington said in an interview Thursday. “So any reduction in heart attack size is beneficial and a 50 per cent reduction is really quite remarkable.”
Redington, who co-ordinated the joint study by researchers in Toronto, Denmark and England, said the idea of ischemic preconditioning first arose about 25 years ago, primarily because of work in laboratory animals.
Scientists found that if tissues are starved of blood in an intermittent manner, it seems to prepare them for a more prolonged interruption in blood and oxygen supply, he said, explaining that halting flow releases a substance into the blood that “circulates and bathes all the organs, not just the heart, to protect them.”