Image: A thermal image of a localized cooled heart (dark spot) (Photo courtesy of Catharina Hospital).
A new study suggests that cooling sections of the heart during a heart attack, both prior to and following an angioplasty, could limit cardiac damage.
Researchers at Eindhoven University of Technology (TUE; The Netherlands), Catharina Hospital (Eindhoven, The Netherlands), and other institutions conducted a study in 10 patients suffering acute myocardial infarction (MI), whose primary percutaneous coronary intervention (PPCI) included selective sensor-monitored intracoronary hypothermia based on saline at room temperature administered distal to the culprit lesion through an inflated over-the-wire-balloon (OTWB), in order to cool the endangered myocardium for 10 minutes.
Once the OTWB was deflated, cooling continued with saline at 4°C for another 10 minutes during the reperfusion phase. A sensor-tipped temperature wire in the distal coronary artery allowed titration of the infusion rate to achieve a desired coronary temperature of 6°C below body temperature, which was achieved within 27 seconds; routine PPCI was then performed. The results showed that in anterior wall MI, the protocol appeared safe, without serious hemodynamic or systemic side effects. In inferior wall MI, transient conduction abnormalities of short duration occurred. The study was published on December 8, 2017, in EuroIntervention.
“You can compare it with cooling the knee following a sports collision, for example, where an inflamed reaction occurs and the knee swells. To avoid this swelling, therefore, the muscles are often immediately cooled. We now apply the same principle to the heart muscle,” said lead author Luuk Otterspoor, MD, of TUE. “By cooling the part of the heart that is affected by a clogged or constricted coronary artery, there is less damage to the heart muscle after the constriction is opened up. We believe this can ultimately reduce the impact of the heart attack and damage to the heart by some 20-30 percent.”
During a PPCI angioplasty procedure, the constricted coronary artery should be opened up as quickly as possible. However, once blood begins to flow again, additional irreversible damage to the heart muscle is caused. This consequential damage, known as reperfusion injury, is the result of heart muscle cells swelling, which causes the capillaries to close. Animal models have shown that hypothermia reduces both reperfusion injury and infarct size, if started before PPCI reperfusion.
Eindhoven University of Technology