Computed tomography versus aortography in diagnosis of aortic dissection

Aorta: comprehensive evaluation by echocardiography and transesophageal echocardiography

The emergence of transesophageal echocardiography has made echocardiography a nearly ideal technique for evaluating the thoracic aorta. The echocardiographic anatomy of the aorta is reviewed. The role of echocardiography for evaluating aortic dissection, thoracic aortic aneurysm, aortic atherosclerosis, and thoracic aortic trauma is discussed. Comparison of echocardiography with other techniques for imaging the aorta (computed tomographic scan, nuclear magnetic resonance, and aortography) is presented.

Diagnosis of acute thoracic aortic dissection using combined echocardiography and computed tomography

Acute dissection of the thoracic aorta is a life-threatening emergency requiring a diagnosis which is rapid, accurate and safe, and which will distinguish between dissections involving the ascending and descending aorta. In the absence of any general agreement on the best method of making this diagnosis we studied the use of combined echocardiography and contrast-enhanced computed tomography (CT) to diagnose acute aortic dissection. Over a 3 year period 23 patients were investigated in this way. Aortic dissection was demonstrated in 18 cases, involving the ascending aorta in 15, and the descending aorta alone in three. The diagnosis of aortic dissection was confirmed in 13 patients at surgery, in one at aortography and in one at autopsy. Three patients died without surgery or autopsy being performed to confirm the diagnosis and the subsequently which accounted for their symptoms. This combined approach has proved a valuable and safe means of investigating aortic dissection.

Use of computed tomographic scanning and aortography in the diagnosis of acute dissection of the thoracic aorta

Before the introduction of computed tomographic (CT) scanning, aortography was the investigation of choice for acute aortic dissection. Between 1978 and 1982, 24 patients were referred to the Brompton Hospital with suspected acute thoracic aortic dissection; all had aortography with diagnosis confirmed at surgery (n = 12) or necropsy (n = 2) or supported by clinical outcome (n = 8). One patient in whom aortography was negative had type B dissection at necropsy and another patient was lost to follow up. CT scanning became available in this unit in 1983 and between 1983 and 1987 was used as the only imaging investigation in 32 patients with suspected acute dissection of the thoracic aorta while in a further 22 patients aortography was used alone. Results were confirmed at surgery (n = 18), necropsy (n = 3), or supported by clinical outcome (n = 31). Two patients were lost to follow up. In an additional 16 patients both aortography and CT scanning were performed with concordant findings in 10. In six in whom the results were discordant, aortography was normal in three in whom subsequent CT scanning showed type B dissection and CT scanning was normal in three patients in whom aortography showed type A dissection. Both CT scanning and aortography are reliable techniques for assessment of suspected acute dissection of the thoracic aorta. Both techniques misdiagnose occasionally and the frequency of misdiagnosis will be minimised by performing both investigations in patients where the level of clinical suspicion is high and the initial investigation negative. CT scanning tends to miss type A dissection and in view of the success of surgery in this condition this failing has the more serious clinical consequences.

Doppler ultrasound in aortic dissections: a study of cephalic and peripheral arteries

We investigated the role of continuous-wave Doppler ultrasound in predicting the presence of an aortic dissection prospectively in 28 patients whose diagnosis was confirmed either by arteriography or surgery (26 cases) or at autopsy (two cases). We hypothesized that dissections, by creating two channels for flow, would produce velocity disturbances detectable in accessible arteries such as the carotid, brachial, and femoral arteries. Of the 28 patients, 20 had Type I, two Type II, and six Type III dissections. Two abnormalities of the Doppler signals were found: in 18 of Type I dissections, notching was found in the systolic upslope of the velocity tracing from those arteries that were either involved in or distal to the dissection sites. Notching was much less frequent for Type II and III dissections: only one patient with Type II and two patients with Type III dissections showed notching. In addition diastolic backflow with marked aortic valvular insufficiency was present. Notching in brachiocephalic artery continuous-wave Doppler signals appears to have a high positive predictive value for Type I dissections.

Abdominal aortic dissection with retrograde extension into the thoracic aorta: case report

A case of spontaneous dissection originating in the infrarenal abdominal aorta with retrograde extension into the thoracic aorta is reported along with the computed tomography and angiographic findings. Surgical repair resulted in the obliteration of the false lumen, healing of the thoracic hematoma, and clinical recovery. The principles for radiologic evaluation and therapeutic management are discussed.

Diagnosis of aortic dissection. Comparison of investigatory methods--case report

A case is presented of a patient with an acute aortic dissection, rapidly followed by thrombosis of the false channel. The classical aortoangiography failed to give adequate information, whereas newer, less invasive investigation methods gave images that finally led to the correct diagnosis. The value of these methods in the diagnosis of aortic dissection is discussed.

Aortic dissection following coronary artery bypass surgery: diagnosis by CT

We describe an unusual case of aortic dissection causing spinal cord infarction. The dissection arose from an intimal tear at the suture line of a coronary artery bypass graft. CT was used to diagnose the dissection and to demonstrate its extension to the aortoiliac bifurcation and innominate artery and its rupture into the left pleural cavity. The most common causes of intimal tears following cardiac bypass surgery are aortic cross-clamping, aortic cannulation, and injury during suturing of the graft to the aorta. An underlying disease of the aorta such as atherosclerosis, cystic medial necrosis, or aortitis is commonly present. CT is an accurate and safe means of detecting aortic dissections following cardiac surgery, and is also useful in assessing the extent of the dissection and identifying its rupture into the pleural or pericardial cavity.

[Dynamic computer tomography following vascular operations in aortic aneurysms or aortoiliac occlusive disease]

Thirty-five aorto-iliac reconstructions (27 aorto-bifemoral Y-grafts, two aortic tube grafts, one aortic endarterectomy, 5 ileo-femoral bypass operations) were studied by CT-scans one week to seven years postoperatively. A General Electric CT/T 8800 with Dynapak software was used. Coronary, sagittal and oblique reconstructions as well as time-density diagrams were performed. There were normal CT-findings in 22 patients (63%), excessive Neointima formation in seven, graft occlusion (one limb of Y-graft) in three, prosthetic dilatation in two and suspicious graft infection in one patient. Patent bypasses showed enhancement of contrast medium. CT-scans corresponded with clinical findings in all instances. Because of its non-invasiveness, assessment of perivascular alterations and semiquantitative measurements dynamic CT is applicable in the follow-up of aorto-iliac arterial reconstructions.