Over the past year, Apple Watches have been credited with detecting heart complications and saving lives on multiple occasions.

Now, a doctor from New York University is suing the tech giant over the feature that made it all possible.

Cardiologist Joseph Wiesel claims that Apple used his patented heartbeat-monitoring technology and integrated it into Apple Watches after he told the tech company about his invention in September 2017, Bloomberg reports.

Wiesel was granted a patent in 2006 for a "method of and apparatus for detecting atrial fibrillation." Atrial fibrillation, or AFib, is an irregular and often rapid heart rate that causes about 750,000 hospitalizations each year, according to the CDC. Wiesel's patent uses sensors and light to detect heart rhythms which can then be shown on a digital display.