In his new book, Dr. Jauhar tells the stories of the intrepid doctors who pioneered cardiovascular surgery in the late 19th century, cutting open patients to deftly repair acute wounds with needles and catgut before quickly closing them back up to avoid heavy bleeding. More complicated procedures, however, necessitated more sophisticated machinery. Surgeons needed a device that could take over the job of the heart so they could temporarily stop the organ from beating and cut into it to repair congenital defects and other chronic problems.

That led Dr. C. Walton Lillehei to develop cross-circulation, a procedure in which a heart patient was hooked up to a second person whose heart and lungs could pump and oxygenate their blood during long procedures. Dr. Lillehei practiced cross-circulation on dogs before finally trying the procedure on humans in 1954. Like other heart surgeons who would advance the field through risky procedures, Dr. Lillehei faced enormous criticism as he tried to break new ground.

“His critics were aghast,” said Dr. Jauhar. “They said, this is the first operation in the history of mankind that could kill not one but two people.”

Some of Dr. Lillehei’s patients survived. Others succumbed to infections and other complications. But the work he did allowed others to develop the heart-lung machine, which today is used in more than a million cardiac operations around the globe each year. Since then scientists have developed procedures that bypass or prop open diseased coronary arteries, as well as implantable cardiac devices and heart medications that save millions of lives annually.

Nationwide, heart disease is still the leading killer of adults. But cardiovascular medicine has grown by leaps and bounds: Mortality after a heart attack has dropped tenfold since the late 1950s. Yet the role that emotional health plays in the development of the disease remains largely underappreciated, Dr. Jauhar says. He traces this to the landmark Framingham Heart Study, started in 1948, which followed thousands of Americans and identified important cardiovascular risk factors like cholesterol, blood pressure and smoking. The Framingham investigators initially considered looking at psychosocial determinants of heart disease as well, but ultimately decided to focus on things that were more easily measured.

“What came out of it were the risk factors that we now know and treat,” Dr. Jauhar said. “What was eliminated were things like emotional dysfunction and marital health.”

That, he says, was a mistake. In the decades since then, other studies have shown that people who feel socially isolated or chronically stressed by work or relationships are more prone to heart attacks and strokes. Studies on Japanese immigrants to America found that their heart disease risk multiplies. But those who retain their traditional Japanese culture and strong social bonds are protected: Their heart disease rates do not rise. Dr. Jauhar argues that health authorities should list emotional stress as a key modifiable risk factor for heart disease. But it is much easier to focus on cholesterol than emotional and social disruption.