Inflating a blood pressure cuff on the upper arm just ahead of heart bypass surgery reduces heart injury and might even improve bypass patients’ long-term survival, according to an Article published in The Lancet.
The study, led by Professor Gerd Heusch of the Institute for Pathophysiology, and Dr Matthias Thielmann, of the Department of Thoracic and Cardiovascular Surgery, both based at the University School of Medicine Essen, Germany, analysed the effects of a procedure known as remote ischaemic preconditioning on patients undergoing coronary artery bypass graft surgery.
Remote ischaemic preconditioning involves briefly cutting off, and then restoring, the blood supply to an area of the body remote from the heart, such as the arm. Although it has been known for twenty years that remote preconditioning reduces injury to the heart muscle, this is the first randomised control trial to determine whether remote preconditioning affects long-term survival after bypass surgery, as well as its effects on other clinical outcomes, such as heart attack or stroke.
After screening nearly 3000 patients of the West German Heart Centre, the researchers allocated 162 patients scheduled to undergo heart bypass surgery to the intervention group. After induction of anaesthesia ahead of surgery, these patients had their blood supply restricted (ischaemia) for five minutes by having a normal blood pressure cuff inflated on their upper left arm, followed by five minutes to restore blood supply (reperfusion) while the cuff deflated, a cycle that was repeated three times. 167 patients undergoing heart surgery were allocated to the control group, and did not undergo remote preconditioning.
After surgery, the researchers measured patients’ blood concentrations of a substance called troponin I, a biomarker protein which indicates damage to the heart muscle, with higher concentrations indicating more extensive damage. Heart muscle damage is a common consequence of complex heart surgery such as coronary bypass, and is associated with poorer long-term survival and other adverse health outcomes, such as heart attack. As well as measuring troponin I concentrations at the time of surgery, the researchers also followed up patients for up to four years after surgery to determine whether the remote preconditioning affected their long-term health.