Low oxygen levels in the heart have been known to be responsible for life-threatening arrhythmias and even sudden death. However, the reason was still uncertain. Now, a new study sheds light on the underlying mechanism of this dangerous heart disorder. The study revealed that, at a low oxygen level, a protein called small ubiquitin-like modifier (SUMO)  which is associated with the inside of the sodium channels starts each heartbeat within a few seconds. The findings offer effective ways to therapeutics to combat late current and arrhythmia linked with heart attacks, chronic heart failure, and other life-threatening low oxygen cardiac conditions.