When the heart muscle cells contract rhythmically and in a well-coordinated way, the heart efficiently pumps blood throughout our bodies. If this rhythmic pumping action is disrupted by an irregular heartbeat (cardiac arrhythmia), our hearts can no longer distribute blood. In extreme cases, this can lead to sudden cardiac death. The electrical signal behind the muscle contraction in the heart is produced by tiny protein molecules in the membrane of our heart cells. Scientists have revealed that sudden death caused by cardiac arrhythmia can be triggered by changes in body temperature.
While studying the proteins that underlie electrical signalling in the heart and subjecting those proteins to conditions that are similar to the stress of exercise, professor Peter Ruben from the Simon Fraser University at Burnaby in British Columbia observed that in some cases, temperature can cause changes that trigger arrhythmia. The research team found a protein that is far more sensitive to temperature than normal.
When the normal body temperature goes up, for example during exercise, or goes down during sleep, the affected protein no longer functions normally. The disrupted protein function causes the electrical signal in our heart to become erratic, triggering an arrhythmia and, potentially, resulting in sudden cardiac death.
Ruben advised, "With this new knowledge, people can examine their family histories and, if sudden cardiac death is part of that family history, or if they suffer from unexplained fainting, they can seek medical advice."
The research team explained, "Temperature fluctuations modify the way all proteins behave, but some DNA mutations can make proteins especially sensitive to changes in temperature. Through a combination of electrocardiograms, genetic screening, and lifestyle management, some tragic deaths caused by cardiac arrhythmia may be prevented."
The study is published in the Journal of Physiology.