A comatose New York woman, kept alive by machines since Nov. 23 in the vain hope that her 21-week fetus could mature to the point where delivery might be possible, died yesterday after suffering a heart attack and internal bleeding.

Physicians at Victory Memorial Hospital, in Brooklyn, N. Y., said they were unable to save 27-year-old Rosemarie Maniscalco's fetus.

Maniscalco went into a coma on Nov. 23, after leaping up from the table at which she was sitting, screaming, vomiting and losing consciousness.

She was at first reported to be brain dead, a term meaning that the brain has ceased all function and that that function can never be restored.Physicians reported later, however, that Manicalco had some very minimal electrical activity in her brain. The exact nature of her ailment has not been established.

The fight to save the woman and her fetus was, according to many experts, doomed from the start. At its stage of development, the fetus would have had to remain in the uretus for an absolute minimum of three moreweeks to have any chance of survival, and probably would have had to remain for another four to six weeks.

Maniscalco's vital functions were being maintained for her artificially, with machines breathing for her, regulating her temperature and heart beat and controlling her blood pressure.

She was being tube-fed in an attempt to keep her calorie intake high enough to maintain her and her fetus.

Over the weekend Maniscalco developed a form of pneumonia, which doctors say is very common in such cases, as well as internal bleeding, which physicians believed was caused by stress ulcers.

It was reported Monday that the patient's condition was stabilizing, but yesterday her system, which was already stretched to the limits, apparently collapsed.

The Maniscalco case was only the second in which physicians have attempted to preserve the remaining life of a severely brain-damaged woman in order to save her developing fetus.

A similar attempt in Colorado last year ended after only 48 hours. The physician in charge of that case, Dr. Edgar Makowski, said he convinced the patient's family to allow him to give up an effort he considered hopeless.

The Maniscalco case was further complicated by the fact that the Brooklyn district Attorney's office was reported to be investigating allegations that Maniscalco might have been beaten. Those allegations were disputed by the physicians attending her who said she showed no signs of physical abuse.