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We read with great interest the article by Bansal (1) on the false
negative diagnosis of aortic dissection with transesophageal echocardiography.
It was interesting that the two cases of type II dissection were
missed on transesophageal echocardiography but were diagnosed
on angiography. About one-third of patients die from aortic dissection
in the first 24 hours (2) and it is for this reason that urgent
diagnosis and management are crucial. False negative exams with
echo has been described and in addition to the anatomic difficulty
with imaging the section of the arch with a type II dissection
it is apparent that 5-13% of acute dissections will not demonstrate
an intimal flap or false lumen (3).
Recently we have seen a 65 year old female with hypertension who
presented with atypical chest pain. She suffered an acute deterioration
in hemodynamics requiring intubation. On computerized tomography
examination there was no evidence of an aortic dissection. She
underwent transesophageal exam which revealed no dissection flap
but "smoke" present in the area of the ascending aorta.
She improved clinically with medical management and underwent
angiography. The angiogram was entirely negative for an aortic
dissection.
The patient had a pericardial effusion and tamponade as well as
a left sided pleural effusion. The pericardial effusion was drained.
Given that she proved clinically no further imaging was carried
out. The patient remained stable over 48 hours and deteriorated
abruptly when she developed chest pain followed by cardiopulmonary
arrest. She complained of chest pain and then went into electroechanical
dissociation and ventricular fibrillation. At pathology the cause
of death was an acute type II dissection.
Contrary to the cases presented in reference 1, we describe an
example of an aortic dissection (type II) that was missed not
only on transesophageal echocardiography but also on angiography.
We speculate that the "smoke" seen may have been significant
in that it indicated a low-flow state present because of the dissection.
Perhaps it would be most appropriate to perform serial exams when
the suspicion of dissection remains high.
REFERENCES
1. Bansal RC, Chandrasekaran K, Ayala K, Smith DC. Frequency and
Explanation of False Negative Diagnosis of Aortic Dissection by
Aortography and Transesophageal Echocardiography. J Am Coll Cardiol
199;25:1393-401
2. Lindsay J. Diseases of the Aorta. Malvern, Pennsylvania, Lea
& Fediger, 1994, p. 137
3. Braverman AC, Harris KM. Management of aortic intramural hematoma.
Current Opinion in Cardiology 1995, 10:501- 504
