The Heart Healers (16 page)

Like Claude Beck decades earlier, Stewart and Falta resorted to manual cardiac compression to maintain life. Now with a chest open, a life hung in the balance. They summoned the hospital’s cardiologist, Major Robert Eckart, to the operating room. There is no textbook, no article, no manual on how to handle this situation. But Eckart was also a specialist in disorders of the heart’s electrical system, and he had an idea on how to pace the heart, how to save the life of a dying soldier. Who could possibly imagine that Major Eckart’s soldier’s chance of survival traces like a perfectly straight line to the surgeons and cardiologists of a prior war? But it does.

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RETURNING FROM THE
war to the private practice of cardiology at Boston’s Beth Israel Hospital, Zoll was referred a sixty-year-old woman who was suffering fainting spells. Finding a heart rate that intermittently dropped into the low 30s, Zoll diagnosed complete heart block. The electrical impulse that began in the atrium was blocked from passing into the ventricle. Her heart was otherwise perfectly normal—with good heart muscle, good valves, and open arteries. Although she was healthy, Zoll knew she was at risk of sudden death, and worse, that he had no effective preventive therapy. It was not long until she fainted and died under Zoll’s care, with him powerless to influence the inevitable event. Zoll reacted to her death as if it was a personal affront to his worth as a cardiologist, hissing, “This should not happen to a heart perfectly normal except for a block of conduction.”

Why the image of a soldier’s heart lying on top of the esophagus in Harken’s operating room rises to one’s consciousness defies explanation, but there it was, in Technicolor. Image, imagination, intuition. Zoll knew that before the war someone doing research in rabbits had demonstrated that an electrical stimulus applied directly to the heart could induce it to contract. He knew from reading hundreds of chest X-ray images that the esophagus briefly touched the heart as it passed behind it from the mouth to the stomach. Zoll had a hunch. Perhaps he could deliver an electrical shock to the heart using an electrode positioned in the esophagus just at the point where it touched the heart.

In his mind’s eye he saw that electrical stimulus pass through the wall of the esophagus and into the heart tissue, which pressed against it. To test his idea, he advanced an electrode on the end of a wire through the mouth and down into the esophagus of an anesthetized dog, until it reached a position just behind the heart. Since his electrical stimulus needed a target, he put a second electrode on the dog’s chest wall. Zoll delivered a brief electrical pulse. Bingo! Zoll’s inspired guess was correct. Each time he delivered an electrical pulse, the dog’s ventricles contracted.

Zoll’s intuition, like all great revelations, was an image that flashed in a receptive mind. After some tinkering, Paul Zoll had a primitive electrical system that delivered a continuous train of electrical impulses, which might be substituted for Nature’s malfunctioning pacemaker. But like many of us who entered cardiovascular research in that era, Zoll was not in the animal lab to study electrical systems. His motivation was bedside-to-bench and back to the bedside. He wanted to treat patients. He had only proved a principle. Although he could artificially pace an anesthetized dog’s ventricle, his system was impractical for patients because, “in an unconscious patient, quickly passing an esophageal wire down is not the easiest thing in the world. You would have to have a pretty stiff wire, and this might also be traumatic.” His invention was dashed on the rocks of impracticality.

Zoll looked again at his dogs, and had a second burst of inspiration: “We realized that dogs have triangular chests … the ‘brilliant’ idea came to me, why not put leads on both sides of the heart externally?” To his delight, his external pacing system also worked, and even more astonishing, “We found that with this new arrangement you could still pace the hearts at about the same thresholds as before.”

If he could pace the heart using two electrodes on the dog’s chest wall, Zoll asked himself, could he do it in humans? Zoll created a bulky one-of-a-kind system for testing in a patient with complete heart block. Since his device had never been used even once in a human being, the jolts of electricity he would deliver through his patient’s chest would result in one of three outcomes. His pacemaker might have no effect at all, it might pace the heart, or it might electrocute his patient. In today’s era of fully informed consent, we can imagine Zoll would have faced an uphill climb in convincing a skeptical institutional review board or even a patient to be his first experimental subject. The range of outcomes Zoll would have to describe reminds me of my medical school partner who mocked our ineptitude by imagining saying to our patient, “Well, sir, it’s either cancer or the common cold, and only time will tell.”

Ironically Zoll’s first patient was his neighbor’s eighty-two-year-old father, who hovered on the brink of death from heart block, having suffered repeated seizures over a period of four hours. “I ran up the four flights of stairs and attached it to the patient,” Zoll recalls to author Allen Weisse. The man’s chest looked like he had been hit by buckshot, with puncture marks from thirty direct cardiac injections of stimulants. Primum non nocere forced itself into Zoll’s consciousness. “By the time we saw him it was clear that he was going to die, so that it would not be unethical to attempt to stimulate him by a method that in itself might kill him for all we knew,” he said. Of course, if Zoll’s device did kill the man, it would be an event lost to history. In those days we buried our mistakes. Zoll attached the electrodes and turned on his machine.

“For twenty minutes we drove his heart. He stopped having seizures,” Zoll noted. Then his patient’s heart simply gave up, and he died. Autopsy revealed a terrible irony. Prior to Zoll’s restoration of a normal heart rate by pacing, one of the thirty intracardiac injections had torn the surface of the old man’s heart, causing unrecognized bleeding and ultimately death, an echo of the nick on Wilhelm Justus’s heart repaired by Ludwig Rehn in Frankfurt, now distant by a continent and half a century.

But Zoll now had proof of principle. Each regular up and down movement of his patient’s ECG was a metaphor for a giant step in the history of medicine. Zoll had taken three steps. He had proven electrical stimuli could cause the heart to contract. He had proven that these stimuli could be delivered safely without touching the heart, through the chest wall. And most tellingly, he had proven that the human heart rate could be controlled by a machine. No doctor could miss the implication of this finding. Zoll’s little jolt of electricity had done more than pace his patient’s heart, it had shocked the world. If his discovery was not resuscitation from death, it was mighty close.

A month later, Zoll got his second patient. Unlike his neighbor, Roger Abrams was only sixty-five years old and was having intermittent fainting spells due to CAD with heart failure. He had a fighting chance of leaving the hospital if he could just survive these acute episodes. Again Zoll’s pacemaker restored the man’s heart rate to normal: “We stimulated him on and off, interrupting our pacing to see if he might pick up a normal rhythm on this own. We did this for forty-eight hours … but his heart did not pick up on its own.”

Had brilliant Boston physician Paul Zoll, he who tolerated no fools, failed to foresee that his laboratory work also carried the possibility of a Frankensteinian outcome? Mr. Abrams was conscious, and looked reasonably healthy. And therein lay the rub. His patient was totally dependent on his machine, Zoll had no way to wean him off it, and the machine was not portable. By the fifth day of pacing, it was not hard to imagine that Paul Zoll had condemned his patient and his medical center to a lifetime of immobilization in his hospital bed. “People began to get nervous, ‘What are you going to do? You can’t let go. You’ve got to keep going.’ Even my cardiac fellow said, ‘Maybe we shouldn’t be doing this. Maybe you’re tampering with the will of God,’” Zoll worried. Had Paul Zoll, like Stevenson’s Dr. Jekyll, gone a step too far, had he countermanded the will of The Maker, and would he now pay the Devil’s price? After fifty-two hours of bedside angst, providence smiled on his diminutive intellectual subject with the prodigious imagination. Roger Abrams recovered his own normal heartbeat. He soon returned home and survived for another six months.

Zoll published his clinical experiments in medicine’s most prestigious journal,
The New England Medical Journal,
in 1952. The electric shocks delivered to Bostonian chests, although sufficient to awaken the entire world of cardiovascular medicine, still led conservative local religious leaders to whisper that Zoll was flouting the will of God. But providence smiled once again, sending Zoll a prominent local monsignor as a heart block patient. Soon thereafter an article appeared in
The Pilot,
America’s oldest Catholic magazine, published by the Archdiocese of Boston. Its author had acquired a new level of perspicacity, one that allowed him to imagine celestial approbation for a local Boston physician’s groundbreaking efforts at resuscitation. “We should not discourage this sort of thing,” the author suggested, because “God works in many wondrous ways, and it is not impossible that he chose this doctor as his instrument.”

The person with the first idea is often not the one recognized by history. In 1932 physiologist Albert Hyman described an artificial pacemaker powered by a hand-cranked motor. He paced animal hearts and possibly a human heart, but if he did, he published no human result. Zoll used a large battery as his power source, and maintained that the electrical output of Hyman’s device was insufficient for human use. As Charles Darwin’s son Francis notes, “In science the credit goes to the man who convinces the world, not to the man to whom the idea first occurs. Not the man who finds a grain of new and precious quality but to him who sows it, reaps it, grinds it and feeds the world on it.”

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OUR MAN-MADE PACEMAKERS
are still a weak sister when compared to the natural pacemaker of the heart, responsible for the heartbeat in every living species. Nature’s pacemaker poses an astonishing, you’re kidding, how-can-that-be, still unexplained fundamental biologic question. In 1997 Boston cardiologist Dr. Herbert Levine reported that within the animal kingdom, heart rate has a clear mathematical relationship to life expectancy. Species with very rapid heart rates do not live long lives and those with slow heart rates do. What makes this relationship so stunning is that it spans an almost hundredfold difference in heart rate among creatures, and fortyfold difference in lifespan. At one end of the spectrum plods the Galapagos tortoise with a life expectancy of 177 years and a heart rate of 6 beats per minute. Near the other end scampers the common mouse, whose heart beats roughly 500 times per minute. Yet over this massive difference, the relationship between heart rate and longevity remains.

Despite marked differences in body size and heart rate, the number of heartbeats in the lifetime of all species is relatively constant, about 700 million beats. Stated simply, each member of the animal kingdom is endowed with the same number of lifetime heartbeats. No one yet knows the reason for this astonishing secret of Nature. Levine speculated that perhaps heart rate is a marker of metabolic rate, and a creature’s metabolic rate in turn determines its lifespan. The candle burning brightest extinguishes first.

There is one conspicuous outlier in the heart rate-longevity relationship. It is we humans, although we did fit the relationship until science nearly doubled our longevity in the past century. The fascinating unanswered question for humans is whether the relationship of lifetime heartbeats to longevity has any medical relevance. Could reduced heart rate prolong lifespan? Although this experiment has never been undertaken in humans, it has been studied in mice. When mice were treated with a heart rate lowering drug, heart rate fell by half, and they survived 21% longer. If heart rate really does influence survival, Levine calculates that a reduction in a human’s average heart rate from 70 to 60 would increase lifespan from 80 to 93.3 years. We do know that exercise in humans significantly lowers resting heart rate and also prolongs life expectancy. Levine ends with the provocative question, “Can human life be extended by cardiac slowing?” Disbelievers can hew to astronaut Buzz Aldrin’s quip, “I believe that every human has a finite number of heartbeats. I don’t intend to waste any of mine running around doing exercises.”

Yet there is reason to think perhaps Levine’s speculation about slowing heart rate has merit. A drug designed to do just that recently was granted “fast track” status by the FDA, a designation reserved for those drugs that both hold substantial promise and fulfill an unmet medical need. Ivabradine slows the heart rate by inhibiting the current within the heart’s natural pacemaker. In a trial 6,500 patients with heart failure and a heart rate greater than 70 were followed for two years, mortality rate in the group randomized to ivabradine was significantly reduced compared to placebo. The investigators concluded that the beneficial effect of ivabradine was due to its heart-rate lowering effect.

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ZOLL’S BREAKTHROUGH WAS
the idea that he could put an electrode on either side of the chest wall of a human being and pace the heart. Yet this lifesaving treatment had one massive limitation. Zoll’s electrical impulses caused not only the heart to contract—the muscles of the chest contracted with as much vigor and enthusiasm as the heart itself. If the heart had to be paced for a long time, Zoll’s patient faced an intolerable choice: live with your chest muscles contracting sixty times a minute or suffer seizures with a high risk of imminent death. For the rare individual with the physical and psychological fortitude to surmount this obstacle, a huge practical hurdle awaited. Outside the hospital the patient needed to have two electrodes on his chest, and to lug along a portable electrical generator. The solution to these problems clearly required two steps: direct contact of the pacing electrode with the heart, and a pacemaker battery that could be implanted within the body.