Hugh Hefner's death was caused by cardiac arrest.

The founder of Playboy magazine passed away peacefully in his home last week at the age of 91, and it has now been revealed that his death came after he went into cardiac arrest and subsequently experienced respiratory failure.

According to his death certificate, which was obtained by The Blast, Hugh was also suffering from Septicemia - which is a severe blood infection - and had recently battled a strain of E. coli infection which was so strong, it was resistant to antibiotics.

Despite his underlying health problems, it was previously reported that Hugh - who was laid to rest over the weekend - was ''loving life'' and ''keeping up his routine'' in his final days.

A source said: ''Hef was loving life. He was social and keeping up his routine. He was sharp as a tack. He was still making business decisions.

''He may not have gone to all the parties. But he loved that they were still going on at his house. He was the same Hef.''

Hugh passed away last Wednesday (28.09.17) at the famous Playboy Mansion in Los Angeles, California.

A rep for the late star said at the time: ''Hugh M. Hefner, the American icon who in 1953 introduced the world to Playboy magazine and built the company into one of the most recognisable American global brands in history, peacefully passed away today from natural causes at his home, The Playboy Mansion, surrounded by loved ones.''

Hugh's son Cooper Hefner, who is the chief creative officer of Playboy Enterprises, praised his father for living an ''exceptional and impactful life'', and admitted he would be ''greatly missed''.

He said in a statement: ''My father lived an exceptional and impactful life as a media and cultural pioneer and a leading voice behind some of the most significant social and cultural movements of our time in advocating free speech, civil rights and sexual freedom.

''He defined a lifestyle and ethos that lie at the heart of the Playboy brand, one of the most recognisable and enduring in history.

''He will be greatly missed by many, including his wife Crystal, my sister Christie and my brothers David and Marston, and all of us at Playboy Enterprises.''