Cocaine-Induced Intramural Hematoma of the Ascending Aorta

Abstract

We report the case of a 35-year-old man who presented at our institution with intramural aortic hematoma shortly after inhaling cocaine and smoking crack cocaine. To our knowledge, such a case has not previously been reported in the English medical literature. Problems of diagnosis and the mechanisms of intramural hematoma and aortic dissection are discussed.

Intramural hematoma of the aorta is a spontaneous, localized hemorrhage into the wall of the aorta. This hematoma is considered a precursor of aortic dissection and forms without an intimal tear. The mechanism by which self-limited bleeding occurs in the outer layers of the aortic media is as yet unknown. ¹

Cocaine inhalation has been reported to produce acute aortic damage such as frank rupture or acute aortic dissection. ² However, to our knowledge, intramural hematoma of the ascending aorta temporally related to cocaine use has not previously been reported in the literature.

Case Report

In March 2000, a 39-year-old, previously healthy man presented at the emergency room after 45 minutes of substernal chest pain radiating to the back, as well as nausea and diaphoresis. The pain began 10 to 15 minutes after the patient had inhaled cocaine for 2 hours and then smoked crack cocaine. An enlarged mediastinal silhouette on the chest radiograph, along with pericardial effusion, aortic root dilatation, and aortic regurgitation on a transesophageal echocardiogram, strongly indicated the presence of an aortic dissection, although an intimal flap was not evident. Subsequent contrast computed tomographic scanning revealed a dilated aortic root with circumferential, contrast-enhanced thickening of the aortic wall (Fig. 1); neither intimal flap nor a double lumen was seen at any level of the aorta. The lesion involved the ascending aorta up to the origin of the brachiocephalic trunk. This finding suggested the diagnosis of intramural hematoma of the ascending aorta.

Fig. 1 Contrast computed tomographic (CT) scan exploration showing a dilated aortic root, with circumferential, contrast-enhanced, aortic wall thickening and the absence of an intimal flap or double lumen. These findings suggest the presence of an intramural hematoma of the ascending aorta.

The patient's hemodynamic status was stable, and the pain soon resolved with control of hypertension. Routine laboratory tests and a 12-lead electrocardiogram excluded myocardial ischemia. On physical examination, all pulses were present and symmetrical. The blood pressure was 195/65 mmHg. Systematic questioning of the patient showed the only apparent risk factor to be recreational cocaine use during the preceding 3 years.

Since aggressive operative management of intramural hematoma of the ascending aorta is our policy, we scheduled the patient urgent surgery. With the patient under deep hypothermic circulatory arrest, we performed aortic root replacement with aortic valve resuspension and distal anastomosis using an open technique. Intraoperative inspection confirmed the presence of a dilated ascending aorta with evident hemorrhage and fresh clots within the aortic wall. No intimal tear was detected at any level of the aorta.

Histologic examination of the excised aorta revealed an intramural accumulation of erythrocytes and signs of mild degeneration of smooth muscle cells. There was no evidence of arteriosclerosis or inflammatory cell infiltration.

The patient's postoperative course was uneventful. He was discharged from the hospital on the 9th postoperative day, and went to a detoxification and rehabilitation facility where he recovered fully. He was in excellent physical condition when last seen, 16 months after surgery. Postoperative computed tomographic scanning revealed normal healing of the aorta.

Discussion

Intramural hematoma of the aorta is a spontaneous, localized hemorrhage into the wall of the aorta. Self-limited bleeding into the outer layers of the aortic me-dia, which takes place in the absence of an intimal tear, occurs by processes not yet understood. ¹ Spontaneous rupture of the nutrient vasa vasorum of the aortic medial layer has been suggested as the initiating cause of intramural hematoma. ³ Aortic intramural hematoma is distinct from, but may be associated with, aortic dissection, and there is some debate as to whether the hematoma is a separate entity or whether it is simply a precursor of a classic dissecting aneu-rysm. ^1,3

Established risk factors for intramural hematoma include hypertension, cigarette smoking, Marfan syndrome, and diffuse arteriosclerosis. ^1,3 In recent years, reports of acute aortic dissection in association with drug abuse have indicated that cocaine, crack cocaine, and amphetamine use are factors in the pathogenesis of acute aortic dissection. ^2,4,5 As far as we know, ours is the 1st reported case of intramural hematoma of the ascending aorta related to cocaine use. The temporal relation between the cocaine use and the onset of symptoms makes it very likely that the drug was associated with the genesis of this patient's condition. The short time between the onset of symptoms and hospital admission, diagnosis, and treatment of the hypertension may explain the lack of progression to dissection. From a clinical point of view, this case emphasizes that a high index of suspicion for structural damage to the aorta should be maintained in any case of acute chest pain temporally related to cocaine use. The lack of an intimal flap as indicated by common imaging techniques should not reassure the clinician until a potentially lethal condition such as intramural hematoma has been excluded.

The mechanism of medial hemorrhage related to cocaine use remains obscure. In the presented case, the lack of specific pathologic findings suggests that the intramural hemorrhage may have been a phar-macodynamic effect of cocaine and not a cocaine-induced vasculopathy.

Vascular effects of cocaine are thought to be triggered by transient severe elevations in blood pressure, causing a shearing effect on the aorta. ⁶ The aorta is a dynamic organ, capable of almost instantaneous changes in size, compliance, and elasticity via a complex regulatory system influenced by hemodynamic factors, systemic and local reflexes, and neurohumoral activation. ⁶ In our patient, drug-induced arterial hypertension was almost certainly the chief predisposing factor of intramural hematoma formation; however, we cannot exclude the possibility that a direct vasoconstrictive effect of cocaine on the aortic vasa va-sorum contributed to the genesis of this condition. ⁶

In conclusion, the presented case indicates that cocaine use may produce a variety of acute aortic diseases. The diagnosis of cocaine-induced aortic intramural hematoma can be difficult, because the absence of an intimal flap is misleading. Further studies on drug-induced aortic diseases are needed to provide new insights on the pathophysiology of both aortic dissection and intramural hematoma.