Restricting blood flow in the arm to protect the heart?

Professor Derek Yellon, The Hatter Cardiovascular Institute, University College London, UK and colleagues studied 57 patients undergoing elective coronary artery bypass graft surgery. Of these, 27 received remote ischaemic preconditioning, namely three five-minute cycles of having the blood flow in one arm restricted using an automated cuff-inflator, with a five-minute periods between each cycle where the cuff was deflated.

The other 30 patients acted as a control group. All patients had the amounts of troponin T in their blood measured before surgery and at 6, 12, 24, 48 and 72 hours after surgery. Troponin T is a cardiac protein which can be released into the bloodstream following the “injury” to the heart during surgery, and release of such proteins is associated with poor short- and long-term clinical outcomes after surgery.

The researchers found the total troponin T released 72 hours after surgery was reduced from 36.12 µg/l in the control group to 20.58 µg/l in the remote ischaemic preconditioning group, a reduction of 43%.

The authors say: “Our study has shown that remote ischaemic preconditioning, mediated by transient upper limb ischaemia, can reduce troponin T in the perioperative period in adult patients undergoing elective coronary artery bypass graft surgery…One might expect that in high-risk patients for whom serum troponin T concentrations are substantially greater, remote ischaemic preconditioning might confer an even greater reduction in myocardial injury.”

In the accompanying Comment, Dr Henry Purcell and Professor John Pepper, Royal Brompton Hospital, London, UK say: “Clearly the technique for remote ischaemic preconditioning needs to be duplicated by equally skilled workers in other cardiac centres in large numbers of patients. In the meantime, if intermittent limb occlusions are consistently shown to reduce myocardial injury during cardiac revascularisation, the implications for practice are immense.”