By Herb Scribner

The preliminary cause of death for Sen. Lindsey Graham has focused attention on aortic dissection, a rare but often fatal condition that can resemble other medical emergencies.

Why it matters: Aortic dissections can resemble heart attacks or pulmonary embolisms, but the conditions are distinct and require different responses.

Context: A D.C. medical examiner's preliminary examination report on Graham shared Sunday said Graham died from an aortic dissection due to arteriosclerotic cardiovascular disease.

- Aortic dissections can strike without warning and are rare, affecting an estimated five to 30 people per 1 million, according to the American Heart Association.

- "It's similar to paint peeling off a wall," says Neel Mansukhani, an assistant professor of vascular surgery at Northwestern University Feinberg School of Medicine. "And that brings a lot of consequences depending on where the tear is."

What to know about aortic dissections

Aortic dissections happen when the inner layer of the body's main artery tears, according to the Mayo Clinic.

- The condition is most common in men in their 60s and 70s. Graham was 71.

- "There are really no warning signs of it unless someone has a history of aortic dissections in the family," says Mansukhani.

There are generally two types of aortic dissections.

- Type A is the more common and more dangerous form because the tear occurs in the section of the aorta leaving the heart.

- Type B happens in the descending aorta, which is further down the chest and can be treated with medication and monitoring.

Aortic dissections can resemble heart attacks and other medical emergencies, with symptoms including severe chest and upper back pain, severe stomach pain, loss of consciousness and shortness of breath.

Dissections are different than aortic aneurysms, which is when a weakened spot in the aorta begins to balloon outward.

- People with an aortic aneurysm have an increased risk of developing an aortic dissection.

Aortic dissection vs. pulmonary embolism

Graham's preliminary diagnosis of an aortic dissection drew immediate comparisons to a pulmonary embolism, especially after Graham had returned to D.C. after a long flight from Ukraine.

- Pulmonary embolisms can occur after someone develops deep vein thrombosis (DVT), when a blood clot forms in the lower body, per the Centers for Disease Control and Prevention.

- The clot can then travel to the lungs, becoming life-threatening.

- These clots develop "if you don't move for a long time," — like when traveling or on bed rest.

Anyone can develop clots that lead to pulmonary embolisms. However, there are factors that increase risk, including:

- Conditions like heart disease, cancer and COVID-19.

- Surgery.

- Extended periods of rest or travel.

- Smoking, obesity, pregnancy.

PEs can be prevented by taking blood thinners, wearing compression stockings, leg elevation and physical activity.

What to know about coronary calcium buildup

Another condition experts highlighted after Graham's death was coronary calcium buildup, which occurs when calcium deposits build up in the heart's arteries, raising the risk of heart disease, per the Cleveland Clinic.

- The condition is often associated with hardening of the arteries — which can lead to heart attacks.

- Though coronary calcium buildup differs from aortic dissection, both conditions share risk factors — including older age, high blood pressure, smoking and cardiovascular disease.