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Cutting off blood supply to limbs before undergoing surgery can help protect heart patients during the operation, according to a new study.

Researchers from the Norwegian University of Science and Technology (NTNU) and the Department of Cardiothoracic Surgery at the St. Olavs Hospital in Trondheim, Norway wanted to understand how shutting off the blood supply to an arm or a leg before heart surgery influenced the muscle of the left chamber of the heart. While this technique, called remote ischemic preconditioning, is nothing new, researchers said that its effects on the heart's left chamber have never been directly observed.  

"During heart surgery we have to stop the blood supply to the heart to be able to operate on it. After some time without fresh blood, the heart will reduce its ability to produce energy because it doesn't get oxygen. When we shut off the blood flow to another large muscle, such as an arm or a leg, the body prepares for an upcoming challenge by mobilizing its defense system," first author Katrine Hordnes Slagsvold, a PhD candidate at NTNU and medical doctor at St. Olav's Hospital, said in a news release.

The latest study involved cardiac tissue from 60 patients who underwent coronary bypass surgery. The patients were randomly assigned to receive RIPC or to a control group. RIPC was conducted by inflating a blood pressure cuff for five minutes three times.

"The heart muscle of the patients who had restricted blood flow to their arm before surgery was able to maintain the same level of energy production during the whole operation, while heart muscle from the other patients' hearts was not. This may be important because heart tissue is dependent on energy to survive, as well as to repair injuries the cells may have endured during surgery," Slagsvold said.

The findings were published in the International Journal of Cardiology.