DISEASES, SIMULATING AORTIC DISSECTION

S. Marchev, R. Tarnovska, K. Byanov, R. Ivanova, Il. Tomov

 

Medical University - Sofia, Department of Internal Medicine, Clinic of Cardiology

Abstract

Of 48 consecutive patients with a clinically suspected acute aortic dissection, more than the half (25 patients) were without dissection, but never the less their in-hospital mortality was high (24 %).They had the following diagnoses: unstable angina in 6 patients, pericarditis in 3, pulmonary embolism in 3, myocardial infarction in 3, musculsceletal pain in 3, aortic regurgitation in 3, and 1 patient each had cholecystitis, hysteria, diaphragmatic hernia or thoracic nondissecting aneurysm. The sensitivity and specificity of transthoracic echocardiography for the presence of aortic dissection were 67% and 80%,respectively, with positive and negative predictive values of 75% and 73%. For computed tomography sensitivity was 80%,specificity 90%, and positive and negative predictive values 89% and 82%, respectively. For aortography sensitivity and specificity were 89% and 100%,and positive and negative predictive values 100% and 91%, respectively.

 

Key words: aortic dissection, diagnosis

 

Introduction

King George II of England died suddenly in 1760. His autopsy was the first description of aortic dissection. Now, 237 years after that aortic dissection is still a difficult diagnosis.

Aortic dissection without treatment is fatal and mortality is the highest in the first days. The prompt and correct diagnosis improves survival[1]. The purpose of the present study was to establish diseases, imitating aortic dissection, that must be ruled out and to evaluate the methods, used for that.

Patients and methods

Patients

Between January 1988 and June 1990, 48 consecutive patients with clinically suspected acute aortic dissection were examined by transthoracic echocardiography, computed tomography (CT) and angiography. The diagnoses were confirmed by angiography (n= 19), surgery (n= 16), and/or necropsy (n= 20). In 4 patients aortic dissection was excluded by establishing a benign clinical course during follow-up. Since the patients had suspected aortic dissection the urgency did not allow double-blinding.

Echocardiography

M-mode and two-dimensional echocardiograms were recorded in 38 patients in standard transthoracic cross-sectional images on all available scan planes with electronic sector scanner (Toshiba) using 2.25 and 3.5 MHz transducers. A diagnosis of aortic dissection was made if two lumens separated by an intimal flap could be seen within the aorta. If a false lumen was completely thrombosed central displacement of intimal calcification or separation of intimal layers from the thrombus were regarded as positive[2].Echocardiograms were also assessed for pericardial effusion. Aortic insufficiency was diagnosed with pulsed and continious wave Doppler echocardiography.

Computed Tomography

Whole-body scanner was used for CT on 20 patients. With the patient supine, 1 cm sections of the chest were scanned every 2-4 cm in craniocaudal direction. Even if the thoracic blood vessels appeared normal on preliminary scans, intravenous enhancement was used to identify a dissection. Aortic dissection was diagnosed if two lumens could be identified in an aorta than was filled with contrast media and separated by an intimal flap. Other less specific findings were aortic widening, medial displacement of pericardial intimal calcification and spiraling of a false lumen around a true lumen[3]. Images were also checked for any pericardial or pleural effusion.

Angiography

19 patients underwent aortic angiography with conventional cinefilm in multiple projections. An angiographic diagnosis of aortic dissection was made if an intimal flap and double lumen could be identified. Indirect signs were a compressed true lumen and thickened aortic wall. Aortic insufficiency was defined as regurgitant flow from the aorta to the left ventricle during injection of contrast material into the aortic root.

Statistical Analysis

The chi-square test was use to test the difference between the patients with and without dissection. Statistical significance was accepted at p<0.05. All values are mean values +- standard deviation. In 48 patients sensitivity (true positives /true positives + false negatives), specificity (true negatives /true negatives + false positives), positive predictive value (true positives/ true positives + false positives) and negative predictive value (true negatives/ true negatives + false negatives) for the presence of aortic dissection were calculated.

Results

Demographics

Aortic dissection was excluded in 25 of 48 patients, in the other 23 it was proved (21 with type A and 2 with type B). The patients without dissection were 23 men (92%) and 2 women (8 %) with mean age 58 ±13 years. The patients with dissection were 18 men (78%) with mean age 53±8 years and 5 women (12%) with mean age 62±7 years.

Final Diagnosis

The final diagnoses are listed in Table I.

Table I Final Diagnoses in 48 Patients with Clinically Suspected Aortic Dissection.

Diagnosis

Patients

Aortic dissection type A

21 (43.8%)

Aortic dissection type B

2 (4.2%)

Unstable angina

6 (12.5%)

Acute myocardial infarction

3 (6.3%)

Aortic regurgitation without dissection

3 (6.3%)

Pericarditis

3 (6.3%)

Pulmonary embolism

3 (6.3%)

Musculosceletal pain

3 (6.3%)

Thoracic nondissecting aneurysm

1 (2.1%)

Cholecystitis

1 (2.1%)

Diaphragmatic hernia

1 (2.1%)

Hysteria

1 (2.1%)

Total

48

Outcome

Of the patients without dissection six died in hospital (mortality 24%), with following final diagnoses: 3 patients with pulmonary embolism, and 1 patient each with myocardial infarction, stroke and sepsis. The patents with pulmonary embolism were not on full anticoagulation for the suspicions of acute dissection.

Comparison with true dissection

The patients without dissection were compared to the rest with documented aortic dissection. The following features were compared: age, sex, prior hypertension, shock on admission, pulse deficits, pericardial effusion, aortic regurgitation and myocardial infarction. The pulse deficits and shock on admission were found to be significantly more frequent in patients with dissection, and the myocardial infarction in patients without dissection (fig 1).

Figure 1. Comparison between patients with and without aortic dissection

All the patients with aortic dissection and shock were with rupture while all the patients without aortic dissection and shock were with pulmonary embolism.

There wasn’t myocardial infarction owing to aortic dissection, while 20% of patients without aortic dissection had myocardial infarction.

Pleural pain was observed among patients with aortic dissection only after rupture in the pleural cavity and these patients were in shock.

In the patients with pericardial effusion without aortic dissection there were laboratory signs of inflammation in contrary to the patients with aortic dissection.

Diagnostic accuracy

The sensitivity and specificity of transthoracic echocardiography for the presence of aortic dissection were 67% and 80% ,respectively, with positive and negative predictive values of 75% and 73%. For computed tomography sensitivity was 80% ,specificity 90% , and positive and negative predictive values 89% and 82%, respectively. For aortography sensitivity and specificity were 89% and 100%,and positive and negative predictive values 100% and 91%, respectively.

Discussion

Once the possibility of aortic dissection has been raised its presence or absence must be confirmed. Aortic dissection is the modern-day “great imitator”[4,5], but also many other diseases imitate aortic dissection[6,7,8,9].

Our study confirms that the nature of pain helps the differential diagnosis between pulmonary embolism and aortic dissection. Pleural pain was observed among the patients with aortic dissection only after rupture in pleural cavity and these patients were in shock.

Aortic dissection presents as acute myocardial infarction only in 1 to 2 percent of the cases owing to an abrupt compromise of the lumen of a coronary artery [10]. The right coronary artery is involved more commonly than the left. In our study there wasn’t patient with myocardial infarction as a result of aortic dissection. Thus if a patient has myocardial infarction, the possibility of aortic dissection is small.

Our results about diagnostic accuracy of the echocardiography and CAT are lower than usually reported[11,12,13,14]. Because of the lower sensitivity and specificity of CAT and in sparing time, when the possibility of aortic dissection is high we proceed directly to cardiac catheterisation. We use CAT only when after clinical and echocardiographic examination possibility for aortic dissection is small and after negative results we stop the studies.

References

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  14. Address for correspondence:

    Dr. Sotir Marchev

    E-mail: .

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