Which body organs are most at risk during a heat wave?

In June 2019, much of Europe was struck by early heatwave, with temperatures reaching nearly 46 Centigrade (115 Fahrenheit) in France, an all-time record.

source https://www.lifetechnology.com/blogs/life-technology-news-blog/which-body-organs-are-most-at-risk-during-a-heat-wave