The preliminary cause of Lindsey Graham's death has been revealed following the senator's sudden passing at age 71.

The preliminary cause of Senator Lindsey Graham's sudden death has been shared after the longtime South Carolina lawmaker died at the age of 71, RadarOnline.com can reveal.

According to the District of Columbia medical examiner's office, an initial investigation determined Graham died from "Aortic Dissection due to Arteriosclerotic Cardiovascular Disease."

The D.C. medical examiner said Lindsey Graham died from an aortic dissection caused by arteriosclerotic cardiovascular disease.

An aortic dissection occurs when a tear develops in the inner layer of the body's main artery, known as the aorta.

The condition is considered a medical emergency and is most commonly seen in older men, according to the Mayo Clinic.

Despite the preliminary findings, the investigation into Graham's death is not yet complete.

"The death certificate will be PENDING until all the toxicological and microscopic testing are finalized and at that point the death certificate will be updated to reflect the cause of death and appropriately classify the manner of death," the medical examiner's office said.

Lindsey Graham's family confirmed the senator died on July 11.

In the family's initial statement released on July 12, Graham's office announced: "On the evening of Saturday, July 11, U.S. Senator Lindsey Graham passed away from a brief and sudden illness."