Michelle Lee knows she should not have another child. Her heart pumps so weakly, beats so irregularly, that she has spent 2 1/2 years on the waiting list for a new one. The strain that pregnancy puts on the body, her doctors had warned her for years, might be more than her feeble heart could bear.

So last month, when she discovered she had accidentally gotten pregnant, Lee faced an agonizing prospect: saving her fetus or saving herself. She loves babies. She was raised in a Pentecostal family. Yet, finally, she went to Louisiana State University Medical Center, the esteemed, century-old hospital here whose cardiologists tend to her heart, and said she wanted an abortion.

The hospital refused.

Sick as she is, a committee of five LSU doctors concluded, her chance of dying was not greater than 50 percent. And under Louisiana law, her doctors knew, a public hospital could not perform an abortion on Lee unless her life was considered endangered. They decided her case didn't meet the test.

Trapped in state law, the prevailing local morality, and a body too infirm for an abortion at an ordinary clinic, Lee, 26, suddenly has found herself an unwitting symbol for both sides in the ongoing abortion wars. In recent days, her struggle to end her pregnancy has geared up national abortion rights groups -- which have dispatched lobbyists here from Washington to assist her -- as well as Louisiana's potent anti-abortion organizations, which have offered their support to LSU.

Lee, a divorced mother of two who lives on a rutted street just across the Red River in Bossier City, has found herself staring into television cameras and on the front page of the local newspaper. This morning, she looked pale but resolute as she boarded an ambulance headed for Houston, hoping there to receive the abortion she could not get anyone to perform in her state.

And she sounded bitter. "These people have taken care of me for five years" at LSU, she said during an interview inside her cluttered cinder-block shack. "They told me I couldn't get pregnant because it'd kill me, and now they're turning their back on me."

A quarter-century after it was legalized by the Supreme Court in Roe v. Wade, Lee's ordeal attests to the unsteady ground on which abortion still rests. With the law guaranteeing a constitutional right to an abortion, the issue has evolved into a question of access. And in the intervening years, many states have enacted measures to restrict the ease with which women can get the procedure.

Across the country, the number of abortions has been falling since 1990. In part, this reflects increased use of contraceptives and a decline in teenage sex -- trends that have resulted in fewer unwanted pregnancies. Yet it is also true that the climate for abortion has grown chillier. Compared with the early years after Roe, there are fewer physicians willing to perform abortions, fewer medical schools training students in abortion techniques, and fewer hospitals willing to permit abortions within their walls.

The climate in Louisiana is not getting chillier; it has always been hostile. The state's abortion rate is 11 per 1,000 women of childbearing age, compared with 20 per 1,000 nationwide, according to the most recent federal figures. Opposition to abortion is firmly fixed in the state's heavy Catholicism to the south toward New Orleans and the widespread Protestant fundamentalism, such as that of Lee's family, here in the northwest corner known as Ark-La-Tex.

The state's version of abortion politics has been fierce. In 1990 and 1991, the legislature in Baton Rouge passed bills to virtually ban the procedure in hopes that such a bold move would be legally challenged and become the vehicle for a Supreme Court ruling to overturn Roe. Both years, the bills were vetoed by then-Gov. Buddy Roemer. The second time, the lawmakers overrode Roemer's veto. It was a spectacular political fight and the only veto override in the state this century.

The law was ruled unconstitutional and never reached the nation's high court. Even so, Louisiana restricts abortion as tightly as any state in the nation. Women can get abortions only if they receive counseling in person by a doctor, then wait 24 hours. Minors must bring a notarized permission slip from a parent.

Another state law forbids any facility that receives public funds "to assist in or to provide facilities for an abortion." That law leaves open three windows: A public hospital can perform an abortion for pregnancies that result from rape or incest, or that endanger a woman's life. Those windows have proven small, indeed. Doctors at LSU have performed only 10 abortions in the past five years. Last year, just three abortions were performed at the Medical Center of Louisiana in New Orleans, the largest public hospital in the state.

It is in the crevices of that law that Michelle Lee, now 10 weeks pregnant, has struggled to fit in. She is so sick that she qualifies for disability benefits, including Medicaid, the federal health insurance program for the poor. But whether Medicaid would pay for the abortion did not influence LSU's decision. The hospital's judgment rested instead on whether the pregnancy was life-threatening.

Lee's first signs of "cardiomyopathy," a condition in which the heartbeat is weak and dangerously out of rhythm, came when she was 17 and could not understand why she kept passing out. Her first son, Kevin, was born five years ago after a relatively easy pregnancy. But she grew gravely ill during her second pregnancy three years ago, and that son, Nicholas, was induced prematurely to ease the burden on her heart. LSU doctors implanted an oblong defibrillator into the wall of her left chest. When her heart falls into a dangerous rhythm, the defibrillator tries to correct the beat by emitting a shock so strong it sometimes knocks her to the ground.

Mindful of the dangers of another pregnancy, Lee's husband had a vasectomy, she said. Since their divorce earlier this year, she has used condoms "every single time" she has had sex, she said. "They failed. This was not on my agenda."

Once she learned she was pregnant she lay awake night after night crying, trying to decide what to do.

After LSU turned her down, she telephoned Shreveport's only abortion clinic, Hope Medical Group for Women. The clinic provides services to about 200 women a month who come from a 200-mile radius stretching into Texas and Arkansas.

Robin Rothrock, the administrator at Hope Medical who took Lee's call on Oct. 8, is a veteran of Louisiana's abortion wars. The day in June 1980 that she opened the clinic, there were six patients and 1,000 protesters. Since 1983, the windows have been covered by cedar boards; she tired of replacing the glass after every shotgun blast.Even now, her clinic is visited periodically by members of a militia group from East Texas, who arrive in military gear via a camouflage-painted bus.

Rothrock's clinic has a policy of accepting even women who have medical problems that others might consider too risky for an abortion outside a hospital. "I rarely refuse a woman," Rothrock said. "It's tricky. If we turn her down, very probably she is not going to get an abortion."

Nevertheless, as she listened to Lee, Rothrock knew that this case required a hospital. And she knew that was a problem. "Having been a provider for almost 19 years, I know of no doctors that would be willing to do an abortion in a hospital. I know no one to call."

She tried several doctors anyway, including the half-dozen who work at her clinic. As she suspected, they said it was impossible. And she called the Washington-based National Abortion Federation, which put its government relations director, Maureen Britell, on a flight here. Britell called the owner of several clinics across the state, and begged him to ask his physicians, to no avail. She skipped Shreveport's second-largest hospital -- a Catholic institution -- and found her calls went unreturned at the third-biggest hospital in town.

Finally, on Friday, she placed a call to Bernard L. Rosenfeld, an obstetrician-gynecologist who owns an abortion clinic in Houston. He found a cardiologist there to help him, then asked Houston's St. Luke's Episcopal Hospital, which agreed to allow him to perform Lee's abortion there Tuesday.

Rosenfeld, who read Lee's medical records, said LSU's decision "is really insane. They are playing horrible roulette. . . . If you take a heart that is failing and increase its workload {during pregnancy}, you have an extremely high chance of death."

LSU's spokeswoman, Elaine King, said the hospital's "decision speaks for itself." Though she wouldn't talk in detail about Lee's case, she said the fact that the abortion was denied implies her circumstances were not considered life-threatening. "We are here to save people's lives, but we also must obey the law that is given to us."

As for Lee, her television was tuned to evangelists this morning as she packed a few clothes and a plastic bag filled with nine kinds of medicine for her ambulance ride to Houston. She wore a purple and gold LSU T-shirt. But when she returns home, she said, she wants to find new heart doctors, at a different hospital. CAPTION: Though pregnancy endangers her life, Michelle Lee was denied an abortion. ec CAPTION: After being refused access to the procedure at a Louisiana hospital, heart patient Michelle Lee prepares to be taken by ambulance to Houston, where she hopes to have an abortion. ec