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For family, doctors, life and death were inseparable

Doctors knew from the start that the procedure wasn’t going to be easy, but when images showed the patients’ tangled insides, they realized that more than a surgical challenge lay ahead.

It was 2016 and a team at MassGeneral Hospital for Children was examining 22-month-old twin girls conjoined at the abdomen and pelvis whose parents had brought them from East Africa to Boston in search of physicians willing and able to take on the profound complexities of separation surgery.

The girls’ care over the following weeks involved some 200 people — physicians, nurses, social workers, technicians, and religious leaders — and a single, searing question: When — if ever — is it OK to sacrifice one life to save another?

The parents, who have requested anonymity, had the final say. But doctors and other hospital personnel, no strangers to illness and death, were plunged into a wrenching examination of both their personal values and the responsibilities of their profession: the obligation to do no harm, the duty to act to save a life, and what happens when those concepts conflict.

“My 14-year-old daughter just asked me … ‘Did you violate the Hippocratic oath?’” said Allan Goldstein, who directed the procedure as the hospital’s surgeon in chief. “I said, ‘First, thank God you’re not a reporter. And second, it’s a great question and I don’t know the answer.’”

Goldstein, also professor of surgery at Harvard Medical School (HMS), got involved in the case when he was contacted by a nonprofit on behalf of the parents, who had struggled to find physicians with the expertise to separate the twins.

The search had come up empty in their home country, where stigma attached to the girls’ condition had made it difficult to take them out of the house, according to a recent report in the New England Journal of Medicine. After the parents shifted their focus to the U.S., some 20 institutions turned them down before Goldstein answered the phone.

“Maybe if you asked me, purely on an intellectual level, I would have admitted there was no hope, but I didn’t want to think about it that way.”

Surgery on conjoined twins is rare, and such a procedure hadn’t been performed at MGH for more than 15 years. Still, Goldstein had been involved in complex surgeries before, and, after reviewing the available diagnostic imaging, he invited the family to fly to Boston.

“They were desperate — certainly eager — to do something to help their children,” he said.

Ethical ordeal

When the family first arrived at the hospital, doctors examined the twins, completed new imaging scans, and then began to think through whether and how the separation could be accomplished.

The girls had faced each other since birth, heads and shoulders separate but lower trunks fused. They shared a liver, bladder, and intestinal tract, their pelvises were intertwined, and they had three legs between them. Their conjoined circulatory systems were most worrisome of all.

Imaging showed that the larger and stronger twin, whose heart, lungs, and circulatory system were relatively normal, was supporting her weaker sister. The weaker twin’s heart had just three chambers instead of the normal four, and irregular blood vessels between the heart and lungs, a critical loop in which blood takes up oxygen and delivers it to the rest of the body.

The most crucial connection was between the stronger twin’s oversized superior mesenteric artery, which normally supplies blood to the intestine and pancreas, and the weaker twin’s abdominal aorta, the main pipeline that brings blood to the lower body.

Tests of the weaker twin’s blood-oxygen levels showed values near normal in her leg and lower body — likely due to her sister’s support — and reduced levels in her upper extremities, where she was more reliant on her own malformed heart and lungs. Doctors realized that if the connection between the girls was cut, the weaker twin’s circulatory system might give out.

They also realized that, given the conjoined circulatory systems, if the weaker twin were to die, her sister would also perish.

In this harrowing ethical territory, with surgery to save one girl almost certain to mean death for the other, Goldstein sought guidance from Brian Cummings, chair of MassGeneral Hospital for Children’s pediatric ethics committee, a physician in the hospital’s pediatric intensive care unit, and an assistant professor of pediatrics at HMS.

Cummings turned to medical literature, looking for guidance from past decisions, including accounts of a 1977 surgery by C. Everett Koop on twins who shared a heart, and a U.K. case in which courts determined that a separation surgery should proceed if it allowed at least one twin to live.

After review, Cummings and his fellow committee members advised that the surgery should move forward, with the parents’ consent. They also recommended that hospital personnel who objected to the procedure be allowed to step away, an option that several physicians exercised, asserting that doctors should not take actions leading to a child’s death, Goldstein said.

Allan Goldstein (left) and Brian Cummings discuss their strategy using a model of the twins’ linked bone structure. Stephanie Mitchell/Harvard Staff Photographer

Separation, and goodbye

Within a few days of the initial meeting with doctors, the weaker twin had developed a respiratory infection that worsened into pneumonia. The illness reduced oxygen to her upper extremities enough that the beds of her fingernails turned blue. Admitted with her sister to intensive care, she received supplemental oxygen, antibiotics, intravenous fluids, and a nasogastric tube for food.

It took a week for the pneumonia-stricken twin to improve and 10 days before the girls could be discharged. Six days later, however, the infection recurred. The weaker twin arrived at the hospital with a temperature nearing 100 and blood-oxygen levels of just 32 percent.

“There was definitely a realization, from the ICU’s perspective … they actually might both die before we could get to an operation,” Cummings said.

The illness heightened the urgency of the situation. One sister was failing. The challenge of assembling and coordinating specialists — including nine surgeons and two anesthesiology teams — still remained. Having spoken to the parents, who made their decision after consulting with a religious leader, Cummings and Goldstein accelerated their plan.

The doctors opted to keep the girls in the hospital after the infection cleared, moving them from intensive care to a regular room, where they could be monitored to ensure they were healthy enough for surgery. The girls connected with their caretakers, Cummings said, singing songs and shaking maracas. They were affectionate with each other, the weaker twin draping her arm over her sister. They were also protective, one protesting and flailing her arms when staff tried to stick the other with needles.

The 14-hour operation involved roughly 50 people, including physicians, nurses, and technicians. It had been carefully choreographed, with one team of specialists taking over, doing its part, and giving way to the next.

Anesthesiologists calibrated the proper dose to sedate two children who shared a circulatory system. Plastic surgeons made the first incisions, heedful of how the bodies would be closed after the procedure. General surgeons separated organs, leaving intact the key artery the girls shared. Orthopedic surgeons worked to untangle the pelvis bones.

Then, stepping forward again, the general surgeons cut the mesenteric artery. The lifeline between the twins was gone.

Researchers create quantum calculator

rogramming a computer is generally a fairly arduous process, involving hours of coding, not to mention the laborious work of debugging, testing, and documenting to make sure it works properly.

But for a team of physicists from the Harvard-MIT Center for Ultracold Atoms and the California Institute of Technology, things are actually much tougher.

Working in a Harvard Physics Department lab, a team of researchers led by Harvard Professors Mikhail Lukin and Markus Greiner and Massachusetts Institute of Technology Professor Vladan Vuletic developed a special type of quantum computer, known as a quantum simulator, that is programmed by capturing super-cooled rubidium atoms with lasers and arranging them in a specific order, then allowing quantum mechanics to do the necessary calculations.

The system could be used to shed light on a host of complex quantum processes, including the connection between quantum mechanics and material properties, and it could investigate new phases of matter and solve complex real-world optimization problems. The system is described in a Nov. 30 paper published in the journal Nature.

The combination of the system’s large size and high degree of quantum coherence make it an important achievement, researchers say. With more than 50 coherent qubits, this is one of the largest quantum systems ever created with individual assembly and measurement.

In the same issue of Nature, a team from the Joint Quantum Institute at the University of Maryland described a similarly sized system of cold charged ions, also controlled with lasers. Taken together, these complimentary advances constitute a major step toward large-scale quantum machines.

“Everything happens in a small vacuum chamber where we have a very dilute vapor of atoms which are cooled close to absolute zero,” Lukin said. “When we focus about 100 laser beams through this cloud, each of them acts like a trap. The beams are so tightly focused, they can either grab one atom or zero; they can’t grab two. And that’s when the fun starts.”

A close up of a laser used in the quantum simulator to trap atoms for manipulation. Jon Chase/Harvard Staff Photographer

Using a microscope, researchers can take images of the captured atoms in real time, and then arrange them in arbitrary patterns for input.

“We assemble them in a way that’s very controlled,” said Ahmed Omran, a postdoctoral fellow in Lukin’s lab and a co-author of the paper. “Starting with a random pattern, we decide which trap needs to go where to arrange them into desired clusters.”

As researchers begin feeding energy into the system, the atoms begin to interact with each other. Those interactions, Lukin said, give the system its quantum nature.

“We make the atoms interact, and that’s really what’s performing the computation,” Omran said. “In essence, as we excite the system with laser light, it self-organizes. It’s not that we say this atom has to be a one or a zero — we could do that easily just by throwing light on the atoms — but what we do is allow the atoms to perform the computation for us, and then we measure the results.”

Those results, Lukin and colleagues said, could shed light on complex quantum mechanical phenomena that are all but impossible to model using conventional computers.

“If you have an abstract model where a certain number of particles are interacting with each other in a certain way, the question is why don’t we just sit down at a computer and simulate it that way?” asked Ph.D. student Alexander Keesling, another co-author. “The reason is because these interactions are quantum mechanical in nature. If you try to simulate these systems on a computer, you’re restricted to very small system sizes, and the number of parameters are limited.

“If you make systems larger and larger, very quickly you will run out of memory and computing power to simulate it on a classical computer,” he added. “The way around that is to actually build the problem with particles that follow the same rules as the system you’re simulating. That’s why we call this a quantum simulator.”

Though it’s possible to use classical computers to model small quantum systems, the simulator developed by Lukin and colleagues uses 51 qubits, making it virtually impossible to replicate using conventional computing techniques.

“It is important that we can start by simulating small systems using our machine,” he said. “So we are able to show those results are correct … until we get to the larger systems, because there is no simple comparison we can make.”

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“When we start off, all the atoms are in a classical state. And when we read out at the end, we obtain a string of classical bits, zeros, and ones,” said Hannes Bernien, another postdoctoral fellow in Lukin’s lab, and also a co-author. “But in order to get from the start to the end, they have to go through the complex quantum mechanical state. If you have a substantial error rate, the quantum mechanical state will collapse.”

It’s that coherent quantum state, Bernien said, that allows the system to work as a simulator, and also makes the machine a potentially valuable tool for gaining insight into complex quantum phenomena and eventually performing useful calculations. The system already allows researchers to obtain unique insights into transformations between different types of quantum phases, called quantum phase transitions. It may also help shed light on new and exotic forms of matter, Lukin said.

“Normally, when you talk about phases of matter, you talk about matter being in equilibrium,” he said. “But some very interesting new states of matter may occur far away from equilibrium … and there are many possibilities for that in the quantum domain. This is a completely new frontier.”

Already, Lukin said, the researchers have seen evidence of such states. In one of the first experiments conducted with the new system, the team discovered a coherent non-equilibrium state that remained stable for a surprisingly long time.

“Quantum computers will be used to realize and study such non-equilibrium states of matter in the coming years,” he said. “Another intriguing direction involves solving complex optimization problems. It turns out one can encode some very complicated problems by programming atom locations and interactions between them. In such systems, some proposed quantum algorithms could potentially outperform classical machines. It’s not yet clear whether they will or not, because we just can’t test them classically. But we are on the verge of entering the regime where we can test them on the fully quantum machines containing over 100 controlled qubits. Scientifically, this is really exciting.”

Other co-authors of the study were visiting scientist Sylvain Schwartz, Harvard graduate students Harry Levine and Soonwon Choi, research associate Alexander S. Zibrov, and Professor Manuel Endres.

This research was supported with funding from the National Science Foundation, the Center for Ultracold Atoms, the Army Research Office, and the Vannevar Bush Faculty Fellowship.