Harry Potter star reveals she has part of a cow’s heart attached to hers after battle with deadly condition

to discuss her love of radishes and coffee ice cream, her health and her new memoir.

“I’ve got a cow’s heart now,” Miriam revealed. “Well, not the whole heart. I’ve had an aortic valve replaced by a cow’s aortic valve.”

Jessie asked if that was “common”, to which the actor quipped: “I think it’s rather refined, actually."

She added that she'd never heard of the operation being done before.

"But it saves you from having open heart surgery, which would be infinitely more invasive.”

Miriam explained how doctors had executed the surgery: “They make two little holes in your groin and then they shove this thing through. And I don’t know how they pull it up, but they sort of pull it up with strings into your heart.

“And then when it comes to the point when it’s in your heart, they pull a little string and it goes, pow!

"And lo and behold, your artery or your aortic valve is shoved unceremoniously to the side, and the cow’s aortic valve says, ‘Moo, I’m here.’ And it’s rather amazing.”

Cow valve replacement surgery has actually .

Called a transcatheter aortic valve replacement, the procedure aims to improve the blood flow in your heart by replacing an aortic valve that doesn’t open fully, according to the .

The procedure involves putting a narrow flexible tube - called a catheter - into a blood vessel in your upper leg or chest and passing it towards your aortic valve in your heart, the charity explained.

The tube is used to fix a replacement valve over the top of your old one.

Discussing her operation with Vogue this past June, Miriam said she'd been rushed to hospital the month before and described her health issue as "unexpected".

The actor added that her medical emergency had made her think about death: “When you're young, you never think about death. You just think about your next f**k basically. I think about death a lot."

Speaking to Jessie and Lennie, Miriam also shared that she would “probably” use a wheelchair soon due to her bad back, but had “just sort of accepted” that it was going to be necessary.

Asked by Jessie about how it feels to be 82, Miriam said: "It feels old, is how it feels."

And being told she's viewed as a "national treasure", she described feeling like "a little old lady, trying to make a living, trying to keep going".

She described becoming more "aware of her vulnerability" as she got older too.

"I have a bad back, I'm probably going to be in a wheelchair soon," the actor stated.

"You have to come to terms with what life throws at you," Miriam went on, saying she had “just sort of accepted” the eventually of not finding it easy to walk for much longer.

She added: "I'm very very surprised to have so much love friendship directed towards me."

The actor released her new memoir Oh Miriam: Stories from an Extraordinary Life, last month