Brian Buxton, M.D.,* George J. Reul, Jr., M.D., and Denton A. Cooley, M.D.. INTRODUCTIOIN. The establishment of proximal control is usually necessary during ...
TRANSDIAPHRAGMATIC APP'ROACH TO THE DESCENDING THORACIC AORTA FOR PROXIMAL CONTROL DURING SURGERY ON THE ABDOMINAL AORTA Brian Buxton, M.D.,* George J. Reul, Jr., M.D., and Denton A. Cooley, M.D.
INTRODUCTIOIN The establishment of proximal control is usually necessary during surgery on the abdominal aorta. In most patients this is readily obtained by clamping near the renal arteries. However in some patients with abdominal aortic aneurysm, or in patients undergoing a second procedure on the aorta, it is difficult to dissect around the aorta in the region of the renal arteries and it is necessary to clamp more proximally. The upper abdominal aorta is difficult to mobilize and an alternative method of achieving proximal control is to divide the diaphragm and clamp the descending thoracic aorta.
OPERATIVE TECHNIQUE A midline incision carried to the xiphoid provides adequate access to the lower thoracic and upper abdominal aorta. With the stomach drawn to the left and the left lobe of the liver retracted superiorly, the lesser omentum is divided to the right of the upper stomach and lower esophagus to display the median arcuate ligament overlying the junction of the thoracic with the abdominal aorta. A vertical incision is then made in the posterior part of the diaphragm between the median arcuate ligament and the esophageal hiatus through which the aorta can be palpated and mobilized by blunt dissection from the loose connective tissue of the posterior mediastinum (Fig. 1). It is difficult because of its deep position, and probably unnecessary, to encircle the aorta. The aorta can be clamped from side to side by a slightly curved aortic clamp passed through the incision in the diaphragm (Fig. 2). Care should be taken during manipulation of the clamp to prevent injury of the aorta or intercostal vessels. Once the clamp has been applied, the structures in the upper abdomen will keep it away from the operative field. Retrograde bleeding from the branches of the upper abdominal aorta can be minimized by the introduction of a balloon catheter into the proximal abdominal aorta.' After completion of the operative procedure, the clamp is removed through the diaphragm which is left unrepaired. From the Texas Heart Institute of St. Luke's Episcopal Hospital and Texas Children's Hospitals, Houston, Texas. *Dr. Buxton is a former fellow in cardiovascular surgery at the Texas Heart Institute; he is now practicing in Australia. Address for reprints: B. Buxton, Warringal Private Consulting Suite, 216 Burgundy Street, Heidelberg, Victoria, 3084. Australia. 290
Cardiovascular Diseases, Bulletin of the Texas Heart Institute, Vol. 4, Number 3
DISCUSSION Control of the descending thoracic aorta may be useful during surgical correction of a ruptured abdominal aortic aneurysm or an aneurysm which extends proximally. The technique may be of value also in the treatment of renal or other visceral arterial lesions where a clamp placed nearby could interfere with the surgical procedure. Second operations on the abdominal aorta in the region of the renal vessels are difficult and dissection around the aorta at this level may be hazardous; under these circumstances, control of the aorta above the diaphragm offers an easy alternative. In complex lesions of the left ventricular outflow tract where it is elected to create a bypass from the left ventricle to the abdominal aorta, exposing the descending thoracic aorta by dividing the diaphragm allows implantation of a bypass graft at the junction of the descending thoracic and upper abdominal aorta.2 An advantage of controlling the aorta in the chest, compared with the
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I,iI Fig. 1. Diagram showing incision in the posterior aspect of the diaphragm between the median arcuate ligament and the esophageal hiatus. 291
abdomen, is the ease with which the aorta can be mobilized. The lower descending thoracic aorta lies free in the loose connective tissue of the posterior mediastinum, from which it can be easily dissected. Further, the descending thoracic aorta is relatively free from atheroma, which facilitates clamping. In contrast, the upper abdominal aorta is surrounded by the celiac ganglia and the crura of the diaphragm and is covered by the peritoneum and pancreas. In addition, the upper abdominal aorta has many branches which add to the difficulty in mobilization. For this reason, some surgeons have used an atraumatic aortic occluder in this area.3 A surgical
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Fig. 2. Diagram showing a curved aortic clamp being passed through the incision in the diaphragm to clamp the descending thoracic aorta. 292
procedure high in the abdominal aorta, for example a renal artery repair, can be performed more readily with the aortic clamp in a proximal position, thus leaving a greater length of aorta beyond the clamp. Transdiaphragmatic control of the thoracic aorta during an intra-abdominal procedure is simpler than making a separate thoracotomy as described by Soyer et al.4 A disadvantage of this technique is that the descending thoracic aorta may be difficult to expose and care is required to avoid damage during either mobilization or clamping. The procedure requires additional dissection and therefore should be reserved for special situations where the usual infrarenal exposure of the aorta is inadequate. Clamping the aorta in the chest does not produce as dry an operative field as clamping below the renal arteries, and additional measures, such as the passage of an intraluminal balloon catheter, may be necessary.' SUMMARY
A technique of mobilizing and clamping the lower descending thoracic aorta from the abdomen through an incision in the diaphragm is described. This technique is simple and may be useful during surgery on the abdominal aorta when it is difficult to obtain proximal control. In addition, certain surgical procedures on the upper abdominal aorta may be facilitated by the use of this technique. REFERENCES 1. Berkowitz HD, Roberts B: New technique for control of ruptured abdominal aortic aneurysm. Surg Gynecol Obstet 133:107-109, 1971 2. Cooley DA, Norman JC, Mullins CE, Grace RR: Left ventricle to abdominal aortic conduit for relief of aortic stenosis. Cardiovascular Diseases Bulletin of the Texas Heart Institute 2(4) :376-383, 1975 3. Conn J, Trippel OH, Bergan JJ: A new atraumatic aortic occluder. Surgery 64:1158-1160, 1968 4. Soyer R, Eisenmann B, Deloche A, Diaimant Berger F, Haas C, Dubost C: Traitement des anevrysmes romputs de l'aorte sous-renale par clampage de I'aorte thoracique descendante et mise a plat de la poche anevrysmale. La Nouvelle Presse Medicale 3:81-82, 1974
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