Acute type-A dissection of the aorta: which diagnostic modes remain for surgical indication?

The natural course of acute type-A dissection of the aorta (AADA) implies a mortality of 50% within the initial 2 days. Preoperative diagnostic tests have to be expeditious while avoiding hypertension and direct manipulation of the aneurysm to prevent aortic rupture. Since 1979, 51 patients have been operated upon for AADA. The diagnosis was established by one or more of the following methods: transthoracic echocardiography (TTE); transesophageal echocardiography (TEE); conventional angiography (CA); intravenous digital subtraction angiography (DSA); and computed tomography with bolus injection of contrast medium (CT). TTE (n = 26) showed a dissection in 72%, suggested an intimal flap in 25%, and missed the diagnosis in 1 case. CT (n = 15) and DSA (n = 10) failed to indicate dissection in 1 case each. CA (n = 27) demonstrated dissection in every case but was the most time-consuming and stressful method. Since the introduction of combined transthoracic and transesophageal echocardiography, no other diagnostic methods have been used. On the basis of this experience, we propose the following diagnostic plan: 1. in AADA, the demonstration of an intimal flap in the ascending aorta by TTE/TEE is an indication for immediate surgery without further diagnostic measures (10 patients: no false-positive findings); 2. if a dissection is suggested by TTE/TEE, then DSA is performed if the supra-aortic branches are suspected to be compromised; CT is preferred if an extrapericardial aortic rupture is suspected; 3. the time-consuming and stressful diagnostic approach of conventional angiography is no longer indicated.