Physicians test hypothermia for heart attacks

Nov. 7, 2002
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JACKSONVILLE, Fla. — University of Florida physicians at The Cardiovascular Center at Shands Jacksonville have joined a national study — ICE-IT — to research the use of mild, controlled hypothermia to limit heart damage during a heart attack.

A heart attack is caused when a heart artery is suddenly blocked, restricting the blood flow to the heart muscle and causing it to die. The ICE-IT study will induce hypothermia-a process that lowers body temperature-on individuals having a first heart attack. As the body temperature decreases, so does the metabolism rate, reducing the amount of blood the heart muscle needs to survive.

“We have known about the benefits of hypothermia since the 1950s,” said Dr. Martin Zenni, a UF clinical associate professor of medicine and the principle investigator for the study. “Similar uses of hypothermia have proven to improve neurological outcome in survivors of cardiac arrest.”

The cooling process begins by inserting a catheter into a large vein in a patient’s leg and directing it through the vein to just below the heart. The catheter tip contains a device that rapidly cools the blood to around 92 degrees, which is then circulated throughout the body. Another catheter is inserted to open the blocked artery using a stent, balloon or an angiojet.

The lowered temperature is maintained for about six hours. Anti-shivering medications are given to patients during the cooling process to disguise the sensation of coldness and to help them remain calm. Afterwards, the patient’s body is warmed for 30 minutes.

Jacksonville resident Joseph Mette, 57, is a first-time heart attack patient and was among the first to have the procedure done.

“I didn’t experience any discomfort during the procedure,” Mette said. “Anything that would help reduce the damage, I was willing to try.”

Zenni explained that traditional techniques to stop a heart attack like balloons and stents have an inherent delay in restoring blood flow to the heart.

“With hypothermia, we hope to significantly slow the rate of heart muscle death and limit heart attack damage,” he said.

Zenni and co-investigator, Dr. Paul Gilmore, a UF associate professor of medicine, also will gather data to determine if hypothermia helps blood flow during a heart attack.

There are minimal risks associated with the new procedure, such as minor bruising and bleeding caused from the catheter insertion. Mette said he has been walking three miles a day since he had the hypothermia procedure in late October. Patients will be randomly assigned to either receive hypothermia and traditional techniques or to receive traditional techniques alone. Individuals must arrive at Shands Jacksonville within 12 hours of the onset of a first heart attack to participate.

The Cardiovascular Center at Shands Jacksonville is the only facility in North Florida involved in this study, which includes 30 facilities and 400 participants nationwide. The center was recently named one of the top 100 heart centers in the country by the Solucient Institute.