It was Nov. 22, 1963; President John F. Kennedy had just been assassinated in Dallas. Lyndon Johnson, soon to become our next president, rushed to the emergency room of Parkland Memorial Hospital.
But then the emergency-room physician saw something that alarmed him.
"His face was ashen," the doctor would later say of Johnson, "and he was holding his chest."
The vice president was examined and had an electrocardiogram and heart enzyme tests. All were negative for a heart attack.
Later that day, Johnson was sworn in as the 36th president on Air Force One, on the tarmac of Love Field in Dallas, before flying back to Washington.
Nine years later, on Dec. 12, 1972, the designer of the Great Society stood on the stage of his newly dedicated presidential library on the University of Texas campus. He was there for the Civil Rights Symposium, marking the opening of his White House files on civil rights.
Suddenly, he was gripped with an agonizing attack of chest pain. Recognizing it as angina, Johnson quietly reached for the nitroglycerin pills he carried and popped one under his tongue.
Johnson then proceeded to deliver his speech: "Whites stand on history's mountain, and blacks stand in history's hollow." The challenge, he said, was to "get down to the business of trying to stand black and white on level ground."
The event so exhausted him that he spent the next two days in bed.
A month later, on Jan. 12, 1973, the former president was interviewed by Walter Cronkite at his Texas ranch. Johnson, his hair looking shaggy, smoked a cigarette on camera. Though he had quit the habit at the pleading of his family after a health scare a few years earlier, he told Cronkite he had decided it was better for his heart to smoke, as he found it soothed his nerves.
Ten days later, Johnson was in his bedroom for his afternoon nap. He called the switchboard and asked for the Secret Service detail leader who was out in a car.
Two agents raced to the bedroom with a portable oxygen unit. They found LBJ lying on the floor beside his bed, already turning blue.
It had been nearly four years since Johnson left the White House on Jan. 20, 1969. He was just 64 when he died.
What was in his medical history that could have contributed to such an early death?
While he was Senate majority leader, Lyndon Johnson suffered a serious heart attack on July 2, 1955. His wife, Lady Bird, thought she had lost her husband.
"Lyndon had turned gray; he didn't look alive, didn't look like he was breathing," she later wrote in the foreword of a book written by her husband's personal physicians.
"It was a heart-stopping moment for me, and it lasted for the next six weeks, which was the routine stay then for heart attack patients," she wrote to introduce LBJ: To Know Him Better by physicians J. Willis Hurst and James C. Cain. "Dr. Hurst became the most important man in my life. He would either save Lyndon or not."
Johnson was admitted to Bethesda Naval Hospital. Hurst, then just 34, diagnosed his acute myocardial infarction, complicated by low blood pressure. Hurst would remain LBJ's cardiologist for the rest of the Texan's life, and later was the principal editor of The Heart, the standard textbook on cardiovascular disease.
Hurst noted that his patient smoked three packs a day, and was "willful, moody, hyperactive." Plus, he proved adept at avoiding doctors' restrictions, especially a ban on radio, television, and newspapers.
LBJ claimed he missed country music and persuaded Hurst to allow a radio in the hospital room. But rather than music, the staff heard news broadcasts coming from the radio, and loud cursing from LBJ over the reports from Capitol Hill.
Hurst did get him to quit smoking and to lose weight but gave up on limiting visitors after LBJ protested his efforts, saying, "Oh, now, look, Doctor, you're not going to count Republicans, are you?"
Johnson kept his vow not to smoke, even through the turmoil of the White House years.
Doctor and patient became close; during Johnson's vice presidency, Hurst traveled with him to 15 countries. As president, LBJ offered Hurst the post of White House physician, but Hurst declined and remained at Emory University.
The president proposed that Hurst join the Naval Reserve and be on duty when LBJ traveled, but the physician refused.
"I can draft you, you know!" LBJ told him.
In March 1970, a year after Johnson left the presidency, severe chest pains sent him to the hospital. Doctors said the pains were caused by angina, not a heart attack. He had gained more than 25 pounds after leaving the White House; the next summer, after suffering more chest pains, he dropped 15 pounds on a crash diet.
But by Christmas 1971, he was smoking again. In April 1972, he had a massive heart attack while visiting his daughter Lynda in Charlottesville, Va.
He suffered severe pain for the last few months of his life and needed supplemental oxygen, but kept on smoking.