Raphael De Geest

ABSTRACT                                                               CURRICULUM                                                  BIBLIOGRAPHY

 

 

Introduction  Aneurysms of the thoracic aorta are a life threatening condition. The survival rate at 5 years vary from 7 to 20% (1,2). The surgical treatment of this pathology positively changes its natural history, resulting in a 5 years survival rate of 60% (3,4). The purpose of this paper is to give an overview on this entity. The aneurysms are located in different segment of the thoracic aorta:   1) ascending aorta;   2) aortic arch;   3) descending aorta;  4) thoracoabdominal aorta;  5) multiple locations.  Aneurysms of the thoracic aorta have different etiologies: 1) arteriosclerosis;   2) cystic medial degeneration;  3) myxomatous degeneration;  4) dissection;  5) infection;  6) trauma;   7) post- stenotic;  8) aortitis  . Surgical manual   The operation is performed when the aneurysm has a diameter of 5 cm or more for patient in good clinical condition, or with symptoms. Patients with increased operative risk are operated for aneurysms of bigger diameter. Every locations demands a different surgical approach.  Aneurysms of the ascending aorta   When anuloaortic ectasia is present the ascending aorta and the valve are replaced with direct reimplantation of the coronary ostia in the conduit. In the absence of anuloaortic ectasia only the ascending aorta is replaced with a sopracoronary conduit. If needed the aortic valve is changed.   Aneurysms of the aortic arch  This location is approached under a period of circulatory arrest, performing first the distal anastomosis. Brachiocephalic vessels are reattached by a single continuous suture to an opening made in the graft. In patient with distal aneurysms the arch graft is inserted in a way to live a segment of the graft left hanging in the distal aorta (elephant trunk procedure).   Aneurysms of the descending aorta  This type of aneurysms is approached through a left posterolateral thoracotomy. The aneurismectomy is performed under cross clamp of the aorta when a clamping time of less than 30 min is expected. If a superior period is necessary partial bypass is used in order to prevent post operative paraplegia. When the exposititon of the proximal aorta is demanding the operation is performed during period of circulatory arrest.   Thoracoabdominal aneurysms  The procedure is performed through a thoracophrenicolaparotomy. Partial bypass without systemic eparinization is used in case of extensive aneurysms. In easier cases the procedure is performed with direct cross clampung of the aorta. The kidney are perfused with cold Ringer lactate in order to prevent renal insufficiency. Intercostal, lumbar and visceral arteries are reimplanted.   Comment   Different procedures have been developed for the tratment of aneurysms of the ascending aorta to reduce peroperative mortality and morbidity (5). When anuloaortic ectasia is present the procedure of choice is the combined replacement of the aortic valce and the ascending aorta with direct reimplantation of the coronary ostia. In absence of anuloaortic ectasia only the ascending aorta is replaced. The aortic arch aneurysms, in the past, have remained a surgical challenge. The use of deep hypotermic circolatory arrest has greatly simplified the surgical approach to this entity. When aneurysms are present in different location is necessary to cure first the life threatening one. The second aneurysm is approached when the general condition of the patient are good (6). Different techniques have been developed to control, during clamping, proximal hypertension and distal hypotension. Hypertension can cause left ventricular failure, while hypotension is essential for the onset of post operative paraplegia and kidney failure. Livesay and coworkers(7) have proved that the risk of paraplegia is significantly increased in case of extensive aneurysms. For this reason partial bypass is used when a cross clamp time of more than 30 min. is expected. In the surgery of toracoabdominal aneurysms is of particular relevance the prevention if paraplegia and of kidney failure. In this instance is used partial bypass without eparinization and intercostal and lumbar arteries are reimplanted. The incidence of kidney failure is superior in older patients and in case of emergency operation. Multiple aneurysms are often present showing a multifocal pathology of the aorta. This is particularly true for patients with Marfan disease. Different studies (8 -9) have demonstrated that the first cause of death in patient operated for aneurysm, is the rupture of a second one. Appears then mandatory a careful follow-up performed with a complete screening of the aorta.The possibility to operate in stable clinical conditions is essential for the survival of the patient. Surgery of aneurysms of the thoracic aorta can, nowadays, be performed with good results. Observing the natural history of the disease an aggressive surgical approach seems advisable.

Fig. 1:Location of aneurysm of thoracic aorta         Fig. 2: Aneurysm of ascending aorta          Fig. 3: Replacement of ascending aorta and aortic valve        Fig. 4: Posterior left thoracic incision and thoracic laparophrenic incision      Vessel tortuosity and tubular eccentricity degrade accuracy of standard two-dimensional measurement. Volumetric analysis allows examination perpendicular to the true centerline of the aneurysm, avoiding such errors        Consecutive 5mm X 2mm helical CT images are obtained through the abdominal aorta

Raphaël De Geest
Department of Thoracic Surgery Onze lieve Vrouw,
Aalst

  Leadership Medica^® 
  Mensile di scienza  medica e attualita` 
 Copyright 1997© All Rights Reserved