Tom Gregory always considered himself relatively healthy despite the fact that he had been diagnosed as having hypertension and told that he had had a heart attack a few years ago. He hadn't spent time in the hospital, so how bad could it have been, he thought. When I first met him, however, that had changed. He knew that something was terribly wrong; he felt sicker than he ever had in his life. My first contact with Mr. Gregory was on the night of his admission to the hospital. He had awakened at home, short of breath and with severe chest pain that radiated to his back. He had become nauseated and vomited. At admission, his blood pressure was 202/110 and his pulse was 98 and regular. He was diaphoretic and felt clammy, and his femoral pulses were unequal. The diagnosis was uncertain: myocardial infarction or aortic dissection. He was given morphine sulphate for pain and was transferred to the ICU. Acute aortic dissection is considered a medical catastrophe, dramatic in its onset with fulminating symptoms and a high mortality. In any previously undiagnosed acute condition of the chest, head, abdomen, or extremities, the possibility of dissecting aortic aneurysm must be considered. An aneurysm is a localized dilatation of a vessel, frequently an artery, and results from blood penetrating the wall of the vessel(l). The aneurysm is said to be dissecting when the vessel wall separates either longitudinally or circumferen-