In their simplest form, such tears can be repaired “fairly easily,” said Dr. Timothy J. Gardner, a spokesman for the American Heart Association and a heart surgeon who is medical director of Christiana Care’s Center for Heart and Vascular Health in Newark, Del.

Dr. Gardner did not know the details of Mr. Holbrooke’s case, but he said, “We have to infer that he had a complicated aortic dissection where one or more of the branches of his aorta were involved and/or the tissue damage and the hemorrhage were extensive and very difficult to deal with.”

In that situation, he said, “it can be a really challenging surgical procedure.”

Dr. Robert Michler, surgeon in chief at Montefiore Medical Center in the Bronx, said that if he is in the operating room in the middle of the night, he is very likely to be repairing a torn aorta. Patients tend to show up with symptoms at night.

“Exactly why that is we don’t know,” he said.

A common symptom is sudden, severe pain in the chest, back or neck. Some people even say they feel a tearing or ripping sensation. Others have no pain. Some have shortness of breath, cold legs, abnormal pulses in their limbs or stroke symptoms like weakness or paralysis. Sometimes blocked circulation causes organs to fail.

The variation in symptoms can make it hard for doctors to figure out what is wrong and lead them to mistake the problem for a heart attack, collapsed lung or ulcer.

Delays in diagnosis can be deadly, because tears in the ascending aorta need emergency surgery. Some people die so quickly they never even make it to the hospital. Among those who do reach the hospital, if the condition is not diagnosed and treated within 48 hours, half will die.

From 80 to 90 percent survive surgery, which involves cutting out the damaged part of the aorta  several inches’ worth in most cases  and replacing it with a tube made of a synthetic material. The aortic valve may also need to be repaired or replaced, and coronary arteries may need to be bypassed.