NEW YORK — She had wealth few could boast and used it to finance a life few would choose — an heiress to the fortune of the founder of Las Vegas spending 20 years voluntarily in New York hospital rooms.

Now Huguette Clark’s reclusive existence is about to be scrutinized in a Manhattan courtroom, where jury selection is due to start Tuesday in a civil trial over her will. With an estimated $300 million at stake, the case broaches questions about aging, caregiving and the line between encouraging gratitude and extracting gifts.

Clark’s distant relatives say hospital executives, a nurse, a lawyer, an accountant and others in her small circle induced a dependent, fragile woman to give them millions of dollars during her lifetime and in her will. The beneficiaries say she was a sharp-minded, strong-willed, munificent person whose decisions were as deliberate as they were unusual.

Signed when the childless Clark was 98, the disputed April 2005 will largely left her estate to arts charities, her nurse and a goddaughter. It provided nothing for her relatives, who were the main beneficiaries of a will she’d signed just six weeks earlier.

“Fundamentally, however, this tragic story presents much more than just a question of whether a particular will is valid or not,” the relatives’ lawyer, John R. Morken, said in a court filing. The larger issue, he wrote, is whether there’s an ethical limit to what caregivers and advisers can ask for or accept — “and if there is, how can professionals and institutions be held accountable?”

The beneficiaries say it’s simply a case of bald-faced greed. And not on their part.

Remote relations who barely knew Clark “claim she should have left her fortune to them, and not those who cared for her in the last years of her life,” lawyer Brian Corrigan, who represents Clark’s own attorney, said Friday.

Clark’s father, U.S. Sen. William A. Clark, made a Gilded Age fortune from Montana copper mines, a Utah-to-California railroad and sales of land around a whistle stop dubbed Las Vegas.

Huguette Clark owned the biggest apartment on New York’s Fifth Avenue, an oceanfront mansion in Santa Barbara, Calif., and a 52-acre estate in New Canaan, Conn.

By the time she died in 2011 at age 104, she hadn’t been to any of them for decades.

Instead, she’d paid about $400,000 a year to live in Manhattan’s Beth Israel Medical Center since 1991, according to hospital records filed in court. She stayed there long after being told she could leave following treatment for advanced skin cancer and malnutrition.

Surrounded by dolls and childhood photos, the woman who liked to be called “madame” got assiduous care from physicians and private nurses.

It became a lucrative arrangement for healthcare providers who got, among other things, a Stradivarius violin valued at $1.2 million.