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Computed Tomography of Ruptured
Abdominal Aortic Aneurysm.
Our Experience at an Insular Hospital

Alonso, Eva M; Lalanza, Juan José;
Utrillas, Raquel; Santos, M. Carmen

Hospital (INSALUD) Can Misses, Ibiza, Spain

SUMMARY
Introduction: CT plays an integral part of the diagnosis and preoperative assessment of ruptured abdominal aortic aneurysm. It is the most feared complication, mortality rate is about 50%.
Purpose: To report our experience of ruptured aortic abdominal aneurysms.
Materials and Methods: CT scans, and medical records of 15 patients, 1990-2000, with this diagnosis were reviewed. All aneurysms were evaluated for: (clinical records: age and gender; maximum aortic size, ratio aortic lumen/thrombus; site of rupture: relationship to renal arteries, aortic side by identifying focally indistinct aortic margin, active bleeding, anatomical spread of hematoma and outcome of the patient).
Results: All patients were males and had poor prognosis, 12/15, 80% died. Averaged age: 65 years. Averaged maximum aortic size: 8cm, range: (5-12) Averaged ratio aortic lumen/thrombus: 0.80, range: (0.50-0.94). Site of rupture: infrarrenal (100%); lateral 40%, posterior 30%, anterior 20%, undefinable 10%. Hematoma extended into one or both anterior or posterior pararrenal spaces: (53%), into perirrenal spaces (33%) and adjacent to aneurysm (13%). We identified active bleeding by using intravenous contrast in (70%).
Discussion: Our results may suggest that the incidence of rupture increases with increasing aneurysm size, above 6 cm. The thrombus may contribute to avoid the rupture Typical findings include: anterior displacement of the aneurysm by a high-density mass that extends into pararrenal and perirenal spaces, a focally indistinct aortic margin that corresponds to the site of rupture.
CT should be done with contrast enhancement to determine active bleeding: its wall may be identified by calcifications while the lumen enhances.
Conclusion: Although rigorous statistical analysis is impossible, we believe the study is representative of clinical practice. We hope it can help to define the role and accuracy of CT in the diagnosis and management of this emergency pathology at our insular hospital.

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INTRODUCTION
   Patients who come to the hospital with a ruptured abdominal aortic aneurysm should be diagnosed promptly. If treatment is delayed, mortality approaches 100%. Patients with classic triad, only 50%, hypotension, abdominal pain, and palpable aneurysm are sent directly to surgery. Ct is usually requested to confirm this suspected diagnosis and to exclude other possible causes of abdominal pain. Ct is the technique of choice for demonstrating a large aneurysm and an obvious retroperitoneal haematoma. However, small ruptures with a little amount of periaortic blood may be difficult to identify. The radiologist should be awared to detect subtles features of an stable aneurysm before it ruptures.

PURPOSE
-   To report our experience: clinical, radiological and outcome of our patients with the diagnosis of ruptured aortic abdominal aneurysms.
-   To describe internal architectural features in ruptured abdominal aortic aneurysms which may be also useful, when no obvious retroperitoneal hematoma is detected, and helpful to predict unstable aneurysms at risk of rupture.

MATERIALS AND METHODS
   Patients were imagined on Siemens-Somaton-DR-non helicoidal CT. Contiguous 10-mm-thick images are obtained from the diaphragm through the pelvis. All patients received oral and i.v contrast material.

    CT scans, and medical records of 15 patients, between 1990-2000, with the diagnosis of ruptured abdominal aortic aneurysm, confirmed by surgery, were reviewed. All aneurysms were evaluated for: (clinical records: age and gender; maximum aortic size, ratio aortic lumen/thrombus; site of rupture: relationship to renal arteries, aortic side by identifying focally indistinct aortic margin, active bleeding, anatomical spread of hematoma and outcome of the patient).

RESULTS
   All patients were males and had poor prognosis, 12/15, 80% died. Averaged age: 65 years. Averaged maximum aortic size: 8 cm, range: (5-12) (Fig. 1). Averaged ratio aortic lumen/thrombus: 0.80, range: (0.50-0.94) (Fig. 2), (Fig. 3). Site of rupture (focally indistict calcium aortic margin) - (Fig. 4), (Fig. 5),-infrarrenal (100%); lateral 40%, posterior 30%, anterior 20%, undefinable 10%. Hematoma extended into one or both anterior or posterior pararrenal spaces: (53%), into perirrenal spaces (33%) and adjacent to aneurysm (13%). We identified active bleeding by using intravenous contrast in (70%).(Fig. 6, Fig. 7)



Fig 3


Fig 5


Fig 7

DISCUSSION
   A ruptured aneurysm is diagnosed by identification of a large abdominal aortic aneurysm and an adjacent retroperitoneal hematoma. Typical findings include: anterior displacement of the aneurysm by a high density mass that extends into pararrenal and perirenal spaces. However, it would be ideal to identify those aneurysm that are unstable and about to rupture, when no hematoma retroperitoneal is present. Although much has been written about the CT appearance of the retroperitoneal hematoma, relatively little attention has been paid to the internal morphology of ruptured aneurysms themselves.

    Our results may suggest that: the incidence of rupture increases with increasing aneurysm size, above 6 cm. The thrombus may contribute to avoid the rupture, and a focally indistinct aortic margin may correspond to the site of rupture.

    CT should be done with contrast enhancement to determine active bleeding: its wall may be identified by calcifications while the lumen enhances.

   Our results are similar to other series, except that the retroperitoneal hemorrhage in other series was most commonly observed in the perirrenal spaces, although our experience is too limited to obtain statistical conclusions.

    Several investigators have suggested that the site of rupture can be tomographic detected as a focal area of indistinctness in the aortic wall, but this sign may be not specific. Fortunately, its identification has no clinical utility and more attention must be paid to the knowledge of renal artery involvement which is very important to the vascular surgeon.

CONCLUSION
  Although rigorous statistical analysis is impossible, we believe the study is representative of clinical practice. We hope it can help to define the role and accuracy of CT in the diagnosis and management of this emergency pathology at our insular hospital.

   On the basis of our limited experience, we have found that the maximum aortic size, the thrombus pattern and an irregular lumina with minimal mural calcifications are more likely to rupture. The retroperitoneal hematoma extended in our serie more in the pararrenal spaces than in the perirrenal location.

REFERENCES

1. Siegel CL, Cohan RH. CT of abdominal aortic aneurysm. AJR Am J Roentgenol 1994; 163: 17-29.

2. Siegel CL,et al. Abdominal aortic aneurysm morphology: CT features in patients with ruptured and nonruptured aneurysms. AJR Am J Roentgenol 1994; 163: 1123-1129.

 

 

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2nd Virtual Congress of Cardiology

Dr. Florencio Garófalo
Steering Committee
President
Dr. Raúl Bretal
Scientific Committee
President
Dr. Armando Pacher
Technical Committee - CETIFAC
President
fgaro@fac.org.ar
fgaro@satlink.com
rbretal@fac.org.ar
rbretal@netverk.com.ar
apacher@fac.org.ar
apacher@satlink.com

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