Rationale and Technique for Replacement of the Ascending Aorta, Arch, and Distal Aorta Using a Modified Elephant Trunk Procedure LARS G.SVENSSON, M.D., PH.D. Department of Surgery, Baylor College of Medicine and The Methodist Hospital, Houston, Texas
ABSTRACT Replacement of the aortic arch during repair of either extensive aortic aneurysmal disease or aortic dissection can be a major undertaking. Borst introduced an “elephant trunk” technique whereby a tubular aortic graft prosthesis was inserted into the distal aorta while repairing the ascending aorta and aortic arch. The distal elephant trunk prosthesis was then used for a second stage operation that involved replacement of sections of the distal aorta. Since then, a few problems have been encountered with the standard elephant trunk procedure and this has led to a modification of the elephant trunk technique, which enables a more accurate and secure distal aortic arch anastomosis to be performed. Using the standard technique described by Borst, the surgeon has to suture in the groove between the tubular graft and the aortic wall, which can increase the risk that torsion on the suture needle will tear the aortic wall resulting in aortic rupture. Indeed, this complication has been noted in the postoperative period when performing the standard technique. Subsequently, the technique was modified with inversion of the graft in itself, placement of the graft in the descending aorta, and performance of the distal anastomosis using a technique similar to that described by Griepp. This has improved the ease of performing the procedure and the results of the technique such that a better than 90% survival rate can be expected for the first and the second stage repairs.
aorta, aneurysm, dissection, arch
The most critical step in the successful repair of extensively diseased aortas is replacement of the aortic arch. In this article, the technique of aortic arch replacement using a modified elephant trunk method as a first step for extensive aortic arch repairs is described in detail with comments concerning ancillary procedures. Address for correspondence: Lars G. Svensson, M.D., Department of Surgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030.Fax: (713)790-0202.
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Aortic arch repla ement using cerebral perfusion was first described by DeBakey and colleagues‘ in 1957. Subsequently, in 1963 Barnard and Schire2 described the first series of replacements of the aortic arch for aortic dissection and degenerative disease in which they used deep hypothermia with circulatory arrest. Later, Griepp and colleagues3 popularized the routine use of deep hypothermia and circulatory arrest for the repair of aortic arch repairs and
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described a technique of performing the distal aortic anastomosis with the graft inverted in the descending thoracic aorta. Replacement of varying extents of the aorta from the coronary artery ostia to below the mid descending aorta remained a difficult problem. To obviate this, Borst et alP95described a dual staged technique by which the ascending aorta and aortic arch were replaced first, leaving a segment of distal tubular graft in the descending thoracic aorta. Borst coined this procedure the “elephant trunk” techniq~e.4~5At a second stage, the distal aorta was repaired beyond the subclavian artery. As is often the case with cardiovascular operations, the operative technique evolves and is modified over time; similarly so has the method of performing the “elephant trunk” procedure over time. The author proposed the modified inversion technique and placement of the graft in the descending aorta in a female patient undergoing an elephant trunk repair under the auspices of Dr. Cosgrove at the Cleveland Clinic in March 1987. Subsequent to the successful elephant trunk repair, the technique was adopted by Dr. Crawford and the author, and has been used in a large number of patients using a distal aortic anastomotic technique similar to that described by Griepp et al.3 Rationale
A serious problem noted with the standard elephant trunk technique was that some patients undergoing the surgery suffered torn aortas at the distal suture lir1e.6~7In these patients, the aorta would rupture into the left chest just beyond the left subclavian artery at the distal suture line with resultant exsang~ination.6~7 The reason for the fatal complication was that a tubular graft was being sutured within the closed confines of another outer tube, namely the aorta. Therefore, this sometimes resulted in tearing of the aortic wall because of the great tension exerted on the wall by the needle during suturing at a difficult angle. In addition, the circulatory arrest period was prolonged with the attendant risk of postoperative neurological deficits. The modified technique, briefly described previously,6,7 of inverting the proximal part of the graft into the distal graft and placing it in the descending
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thoracic aorta resulted in easier suturing of the graft into position at the subclavian artery with a concomitant improvement in results, particularly for those patients with aortic dissections in whom the operative mortality rate for the modified elephant trunk technique has been reduced to only 5%. Apart from simplifying the insertion of the prostheses, the technique enables a greater surface contact area between the graft and the aortic wall after the inverted tube graft is withdrawn for the aortic arch replacement.When the graft is sutured into position, the graft is doubled over on itself. When it is unfolded by withdrawing the inner tube as shown in the figures, the suture is pulled taut since it is now wrapped around approximately twice as much as the distance of the graft. This is analogous to a rubber band around a book that gets stretched to twice its length by opening the book. This increased surface area and tightening of the suture line results in a reduced risk of bleeding at the distal anastomosis. Since it is easier to suture the distal anastomosis as shown by Griepp et al.3 with the graft inverted in the descending thoracic aorta, there is no need for torsion on the needle to suture through the graft and the aortic wall within the confines of the crevice between the graft and aortic lumen. Thus, the risk of tearing of the aorta is considerably lessened. In summary, the modified technique described in this article is the author’s preferred method of performing the procedure based on the evolution of the original technique reported by Borst and thereafter successfully applied by Cosgrove and Crawford using a distal anastomotic technique similar to that described by Griepp. Using the technique described next, the aortic arch can be replaced within a circulatory arrest period of approximately 30 minutes with a reduced risk of bleeding at the distal anastomosis and at the aortic arch anastornotic sites. METHODS
Operative preparation and anesthesia
The elephant trunk procedure is indicated for those patients who have combined diseases of both the ascending aorta plus aortic arch segments and in the distal aorta, namely either des-
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cending or thoracoabdominal aneurysm segments. A further second stage procedure will be required after the aortic arch has been repaired. The procedure can also be used for patients with type I aortic dissection in whom it is expected that the proximal descending and thoracoabdominal aorta will dilate with time. In these cases, an elephant trunk in the descending aorta will considerably simplify the second stage procedure. Preoperatively, patients undergo computerized axial tomograms to assess the extent and size of the aneurysmal disease and aortography for delineation of occlusive disease and planning of the operative procedure. A 24-hour Holter ECG examination, echocardiogram with color Doppler spectral analysis, and pulmonary function tests are routinely obtained. Cardiac catheterization of the coronary arteries and left heart ventriculogram are obtained whenever feasible. Anesthesia is conducted for the first stage and second stage procedures using bilateral radial artery cannula; at least two large-borevenous infusion cannulas; Swan-Ganz monitoring with mixed venous oxygen saturation monitoring; and, on occasion, right-sided cardiac indices with a right heart ventricular function catheter. When available, transesophageal echocardiography (TEE) is useful to monitor perfusion of the ascending aorta and aortic arch during cooling and to ensure that, at the end of the procedure, both aortic dissection lumens are perfused by the distal end of the elephant trunk. When time allows, preoperative autologous blood, plasma, and platelets should be obtained for intraoperative transfusion. At least 20 units each of red blood cells, fresh frozen plasma, and cryoprecipitate should be available for transfusion if required. One L of plasma-pharesed, platelet rich plasma is extracted from the patient as soon as possible after the induction of anesthesia. Patients are cooled until the electroencephalogram (EEG) shows no activity at 5-@Vsensitivity for 5 minutes, and bladder, rectal, nasopharyngeal, and esophageal temperatures are all below 20OC.8 The head of the patient is also surrounded by ice packs. More recently, retrograde perfusion of the superior vena cava by oxygenated blood from a Y arm off the arterial
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line has been used to perfuse the brain in 35 patients at our institution. This approach, however, is still too new to fully assess the results. The alpha-stat method of pH control during cardiopulmonary bypass is adhered to, i.e., the cold blood pH is not corrected to normal body temperature (37OC) and is maintained at pH 7.4W Prior to circulatory arrest, 5 mg/kg of sodium thiopentothal is administered intravenously in the event that there might be residual electrical activity.10 Steroids are not used since in a retrospective review (unpublished data), patients did not appear to benefit from 2 g of intravenous methyl prednisone. Furthermore, the risks of sepsis and multiple organ failure appear to be increased in patients who have received high doses of steroids. Operative technique The operative technique for repair of aortic dissections, ascending aortic arch aneurysms including the use of composite valve grafts, and Marfan syndrome have been reported)'-13 The technique for replacement of the aortic arch will be described. The femoral artery and vein are exposed in the groin, usually the right since it is less likely to be dissected, and then the vessels are looped with umbilical tape. The chest is opened through a standard midline incision and the pericardium opened. For those patients who previously had multiple cardiac operations or who have extensive aneurysms eroding the sternum, femoral artery-femoral vein bypass is instituted prior to sternal entry. In these instances, the patient is then cooled until EEG activity is absent, the circulation is arrested, and the sternum is opened. Two pump suction lines should be available in the event that the aneurysm is inadvertently opened. The aortic arch is exposed on its left anterior lateral surface to approximately 2 cm beyond the left subclavian artery. The plane of surgical dissection is kept close to the aorta to avoid damage to the phrenic nerve and to ensure that the left pleural cavity is not entered. Furthermore, electrocautery is avoided to reduce the risk of phrenic nerve damage. The vagus nerve and recurrent laryngeal nerves are preserved by dis-
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secting close to the aorta. The head vessels are not dissected out or mobilized since this causes unnecessary bleeding, and they are well visualized from inside the aorta. The patient is placed in a steep Trendelenburg position to prevent air accumulating in the arch vessels. Depending on the size of the aorta, a 23- to 30mm woven Dacron tubular prosthesis is selected for insertion and a 10-mm woven tube graft is selected for perfusion of the arch. These grafts are painted with a 25% solution of albumin with the grafts thoroughly stretched to ensure that the albumin fully penetrates the interstices. The prostheses are gently dabbed with a four-by-four sponge so that they are not excessively wet, and then a dry four-by-four sponge is placed internally in the aortic prosthesis, and the grafts flash sterilized for 5 minutes. This should result in a graft that is neither wet nor flaky, with the result that it will neither ooze nor result in embolization of albumin flakes to the brain. The four-by-four sponge is removed after baking the graft, and the 10-mm graft is anastomosed end-to-side to the larger aortic graft (Fig. 1A). To simplify anastomosing the tube graft to the aorta distal to the left subclavian artery, a staysuture is placed on the proximal end of the tube
graft. The suture and the proximal end are then inverted so that the proximal part with the adherent 10-mm side graft is invaginated into the more distal tubular graft (Fig. 1B). A hemostat is kept on the stay suture for later withdrawal of the inverted part of the tube graft. The end-to-side anastomosed 1O-mm tube graft is also inverted. The 10-rnm graft can easily be moved around during suturing without it obscuring the field. Furthermore, during removal of the inverted proximal end, the 1O-mm graft can also be gently tugged upon. Since the 10-rnm tube graft is already anastomosed to the aortic arch graft, the period of circulatory arrest is shortened. To save time prior to circulatory arrest, the anastomosis of the 10-mm graft to the proximal tubular graft should be performed and then inverted into the distal graft. The patient is placed on femoral arterial, and bicaval venous cardiopulmonary bypass after which atrioventricular venting and cooling are begun. During cooling, the ascending aorta and arch should be gently palpated at regular intervals to ensure that the measured radial arterial pressures correlate with the palpated pressures. The reason for this is to detect, particularly in those patients with aortic dissection, whether the
f
A
B
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Figure 1. (A) Inversion of the stay suture into the graft. (6) Inversion of the side arm into the graft.
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aortic arch vessels and brain are being adequately perfused. Although regular monitoring of the right radial artery pressure will usually alert the surgeon to the potential problem of an inadequate aortic arch perfusion pressure, this is not always the case. For example, the innominate artery may only be perfused by one lumen of the dissected aorta with no communication with the other lumen. Also, if the aortic dissection septum acts as a flutter valve, then selective nonperfusion of the head vessels can occur. Furthermore, solely monitoring the EEG without taking other factors into consideration may be unreliable because the EEG may show no brain activity, suggesting that hypothermia is adequate when, in fact, the cause is brain ischemia. The nasopharyngeal and esophageal temperatures should usually decrease more rapidly than the rectal and bladder temperatures. Indeed, a failure of esophageal and nasopharyngeal temperatures to adequately and rapidly fall should alert the surgeon to check forthe problem of nonperfusion of the head vessels. When the palpated pressures are normal and the EEG shows no electrical activity, then cardiopulmonary bypass is stopped and the patient is placed in a steep Trendelenburg position with circulatory arrest. The aneurysm is opened be-
tween two stay sutures and all blood is evacuated by pump suction and the left atrioventricular sump drainage (Fig. 2A). Hyperkalemic blood cardioplegia at 4OC in addition to topical hypothermic saline solution without ice are used for arresting cardiac contraction. After administration, topical hypothermic saline is removed from the pericardial well because it runs into the operative field and increases the risk of phrenic nerve damage in association with deep hypothermia. The aorta is opened along the arch and a stay suture is placed through the aorta proximal to the innominate artery (Fig. 2B). The incision is then continued to the right and then transversely across the back of the aorta at the level of the right pulmonary artery, completely transecting the aorta (Fig. 25). Distally, the aortic incision is taken to an anterior lateral position above the subclavian artery origin. In those patients with chronic aortic dissection, the septum is excised as far as possible in the descending thoracic aorta so that true and false lumens are perfused distally by the elephant trunk. To check that the elephant trunk does not preferentially perfuse only one lumen, an intraoperative TEE is useful to show that both lumens are perfused. In patients with acute dissection, replacement
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Figure 2A. Incision and opening of the ascending aorta and arch.
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Figure 2C. Placement of the inverted aortic graft into Figure 2B. Pansection of the ascending aorta and
the descending thoracic aorta.
aortic arch. Note stay sutures for retraction.
of the entire aortic arch is usually avoided. The exceptional cases include when the aorta is aneurysmal; rupture has occurred in the arch; and the descending thoracic aorta is aneurysmal and needs to be replaced at the same time because of severe back symptoms suggesting impending rupture of the descending thoracic aortic. In such patients, a Carrell patch from the aortic arch is mobilized. A matching piece of Teflon patch is then cut with an inner hole (doughnut shaped) to fit the greater vessels. Next, the Carrell patch is threaded through the Teflon doughnut opening and secured by a few interrupted sutures to sandwich the layers.G,* The inverted graft is placed in the descending aorta and a secure suture is performed just beyond the subclavian artery between the aorta and the doubled over edge of the tube graft (Figs. 2C and 3). The virtue of this procedure is that a hemostatic suture is inserted without undue torsion on the aortic wall. Furthermore, when the inner tube graft is pulled out, the suture line is automatically tightened due to unfolding at the suture line and the contact surface areas at the
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\? Figure 3. Suturing of the graft into position at the left subck~vianartery
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anastomosis are increased (Fig. 4A). Ticron 2-0 pledgeted, horizontally placed valve sutures (Davis & Geck, Wayne, NJ, USA) are used to further strengthen the anastomosis prior to everting the inner tube. After completion of the anastomosis, the stay suture and side arm are gently tugged upon to remove the inverted proximal graft from the distal elephant trunk and the arch vessels are then ready to be reanastomosed (Figs. 4B and 4C). Next, an oval hole is cut in the graft opposite the arch vessels. Reattachment of the arch vessels is then performed (Figs. 48 and 4C). While the patient is kept in a steep Trendelenburg position, the cardiopulmonary bypass pump is slowly restarted through the femoral artery cannula. Any potentially embolic material in the initial blood return is suctioned from the arch, and the greater vessels are allowed to fill. Gentle compression of the vessels ensures that no air pockets are present. The blood is allowed to exit through the proximal aortic graft and from the 10-mm side arm. When the return is free of air or any possible emboli, the other arterial arm of the cardiopulmonary bypass pump is connected to the 10-mm side arm (Fig. 5). All air is carefully evacuated from the aortic graft and 10mm side arm. The descending aorta is usually not punctured to aspirate air because if it is aneurysmal, this can result in severe hemorrhage that can be difficult to control if the aorta tears. Furthermore, if blood has not been completely evacuated from the descending thoracic aorta beyond the anastomosis and blood flow to the brain is reestablished via the side arm on the aortic arch, the risk of air embolization to the brain appears to be minimal. It should be noted that blood is not pumped from the femoral artery without the graft being undamped so that no air is inadvertently embolized to the brain. A plastic band should be applied to secure the position of the cannula in the side arm (Fig. 5). The proximal aortic tube graft is then clamped, and cardiopulmonary bypass is restored to normal flow and warming commenced (Fig. 5). The aortic graft at the highest point above the innominate artery but proximal to the clamp should be punctured with a needle a couple of times to allow any possible air in the graft to escape. Unless retrograde cerebral perfusion is being used or if no valve or coronary artery bypasses are
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needed, then blood in the cardiopulmonary bypass pump should be warmed prior to restarting cardiopulmonary bypass. The ascending aorta is replaced by completely transecting the aorta, just above the coronary artery sinuses, and performing a running suture without using Teflon felt6.8 (Fig. 5). By abandoning the inclusion technique, particularly the Bentalt composite valve graft technique for proximal anastomosis, the incidence of false aneurysms is reduced, including those patients with aortic dissection and Marfan syndrome.1’-14 For composite valve graft replacements, the preferred methods should be either reanastomosing the coronary arteries as buttons containing the ostia or using the modified Cabrol technique of an interposed Dacron tube graft to bridge the gap between the coronary artery ostia.11 This latter procedure allows for the insertion of the composite valve graft conduit without imposing undue tension on the coronary anastomoses. An alternative technique is to place a single tube graft to the left main coronary artery and use the button technique for the right coronary artery as previously described.15 Occasionally in a patient with acute aortic dissection in whom the coronary arteries cannot be reattached, the ostia need to be oversewn and distal coronary artery vein bypasses to the coronary arteries performed as necessaryW11 It is important to ensure that hemostasis is achieved at all the anastomoses prior to discontinuing cardiopulmonary bypass, and this is conveniently done during rewarming of the patient. After administration of protamine, the plasmapharesis concentrate is reinfused, and every 20 to 30 minutes, blood samples are sent for coagulation analysis to guide the administration of blood products until all clotting deficiencies are corrected or bleeding has stopped. During the postoperative period, the patient is treated, if necessary, with inotropes, vasodilators, and blood products. The standard postoperative care is similar to that for any patient undergoing cardiopulmonary bypass and coronary artery bypass. Blood products, however, should be used liberally i f there is any evidence of excess bleeding and, thus, any deficiencies in the coagulation profile are corrected to normal. Since these patients are usually fluid overloaded by the end
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bJ
Figure 4. (A) Removal of the inner tube graft and side arm from the distai aorta. (6 and C) Anastomosis of the arch vessels to the opening in the aortic graft.
of the procedure, dopamine is used liberally, as is LasixR (Hoechst-Roussel Pharmaceuticals Inc., Somerville, NJ, USA), to encourage diuresis. An AmicarR (alpha aminocaproic acid [Lederle Laboratories, Wayne, NJ, USA]) intravenous drip is also used in most patients at 1 to 2 g/hour for 6 hours after the initial loading dose of 5 g. Within an interval of 6 weeks to 3 months, the
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patient is readmitted for the second stage of the elephant trunk procedure. The use of the elephant trunk technique has simplified the second stage operation as a proximal indurated aorta does not have to be mobilized or crossclamped, and often, especially with descending thoracic aortic aneurysms, only one distal anastomosis is required. Whenever possible, segmental intercostal and lumbar arteries from
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Figure 5. Reestablishment of blood flow to the brain and completion of the proximal anastomosis.
vertebral levels F8 to L-2 are reattached to enable reestablishment of blood flow to the spinal cord by the artery of Adamkiewicz and higher thoracic spinal radicular arteries. The operative technique for the second stage procedure is essentially the same as that for the standard descending thoracic or thoracoabdominal aortic aneurysm repairs as described previously.6.8 The patient is placed in a left thoracotomy position with the pelvis tilted to approximately 60° to the table, depending on how low a position on the aorta the distal anastomosis is going to be performed. Both groins are prepared in the sterile operative field in the event that the femoral arteries need to be cannulated for pump bypass. The chest is opened through a standard thoracotomy incision unless the abdominal part of the aorta also needs to be replaced (Fig. 6, panel 1). For replacement of the abdominal section of the aorta, the incision is directed toward the umbilicus (Fig. 6, panel 2). This is in contrast to the usual thoracic incision along the ribs because at the angle formed at the junction of the abdominal midline incision and the thoracotomy incision, the lower skin flap tends to necrose,
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resulting in a large defect. The sixth rib is resected, and if more exposure of the aorta is needed at the subclavian artery, the fifth rib can be divided posteriorly, although this is rarely necessary for second stage elephant trunk procedures. The subcostal margin can be divided and the diaphragm preserved for repairs above the celiac artery, although for aneurysms extending below the superior mesenteric artery, division of the diaphragm is usually necessary. Either an extraperitoneal or intraperitoneal approach to the abdominal aorta can be used since there appear to be no differences in the incidence of respiratory complications according to a prospective study of respiratory failure.le The aorta at the site of the distal anastomosis is mobilized and encircled but no umbilical tapes are passed around it. The site of the previous distal elephant trunk anastomosis is identified immediately beyond the left subclavian artery and then the anterior lateral aorta is longitudinally opened with a scalpel. The thrombus surrounding the distal elephant trunk will usually enable the surgeon to identify the graft without the loss of blood, after which the graft is encircled and clamped (Fig. 7A). If bleeding should occur upon
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Figure 6. Incisions for second stage descending thoracic aortic or thoracoabdominal aortic repair.
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Figure 7A. Clamping of the elephant trunk in the descending thoracic aorta.
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MODIFIED ELEPHANT TRUNK PROCEDURE opening the aorta, the graft can be quickly clamped. Since the possibility exists of the patient exsanguinating during this maneuver, it is advisable to have two autotransfusion devices available for aspirating blood and venous access sufficient for rapid reinfusion of blood. The blood does not need to be washed as long as protamine is administered at a later stage to reverse effects of the heparin mixed with the blood during suctioning. The distal anastomosis is performed either to the circumferentially transected aorta in a standard manner or to an interposition graft if the elephant trunk is not long enough to bridge the gap to the distal aortic anastomosis (Fig. 78). RESULTS
The elephant trunk operative technique has been used in 84 patients with a 30-day survival rate of 92%.9,’70f the patients surviving surgery, 56 patients have undergone second stage op-
erative procedure with a 30-day survival rate of 96%P.17 The median interval between procedures was 62 days with a range of 0 (second stages done immediately after the first stage procedure) to 358 days. Two of the initial deaths from the first procedure were due to rupture at the distal suture line in patients who underwent the procedure using the standard technique, but this has not been a problem using the modified elephant trunk technique in 1988. The net result is that nine patients had replacement of the entire (total) aorta; 27 had replacement of the ascending aorta, aortic arch, descending thoracic aorta, and upper abdominal aorta; and 22 patients had the entire thoracic aorta replaced. Seven of the 84 patients died within 30 days of the elephant trunk procedure. Four deaths were the result of ruptures in the distal aneurysmal aorta (two at the distal elephant trunk anastomosis at the subclavian artery as noted previously), one death was due to multiple organ failure, one to stroke, and one to respiratory failure. One patient
interposit io n g raft Figure 78. Insertion of the interposition aortic graft for completion of a thoracoabdominal aortic repair, resulting in the entire aorta being replaced. Note reattachment of intercostal arteries and visceral vessels. For repairing short descending thoracic aortic aneurysms, an interposition graft is usually not necessary and only one anastomosis is required with the distally transected aorta.
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developed permanent paraplegia after the elephant trunk procedure, and two developed paraparesis. This was probably due to the distal elephant trunk in the descending aorta being too long with the formation of thrombus around the graft, and occlusion of critical intercostal arteries
supplying the spinal cord.7 In conclusion, although patients who present with aortic aneurysmal disease requiring replacement of the ascending aorta, aortic arch, and distal aorta have to undergo extensive and high-risk surgery, with the technique described, a survival rate of 90% to 95% can be expected. This includes similar survival rates for the second stage procedure, resulting in a reasonable quality of life after this type of surgery and a reduced risk of death due t o rupture. This type of salvage surgery is recommended in those patients who are good-risk candidates for undergoing extensive aortic surgery. Acknowledgments: The author gratefully acknowledges permission from Dr. Cosgrove and Dr. Crawford to present this technique and from whom the author learned invaluable technical points. Without their contributions, this technique would not have evolved. Marion Robinson, Ph.D., kindly edited the paper, and Carol Pienta Larson drew the figures.
REFERENCES 1. DeBakey ME, Cooley DA, Crawford ES, et al:
Successful resection of fusiform aneurysm of aortic arch with replacement by homograft. Surg Gyn Obstet 105:656,1957. 2. Barnard CN, Schire V: The surgical treatment of acquired aneurysms of the thoracic aorta. Thorax 18:101, 1963. 3. Griepp RB, Stinson EB, Hollingsworth JF, et al: Prosthetic replacement of the aortic arch. J ThoracCardiovasc Surg 70:1051,1975. 4. Borst HG, Walterbusch G, Schaps 0:Extensive aortic replacement using “elephant trunk” prosthesis. Thorac Cardiovasc Surg 31 :37, 1983. 5. Borst HG, Frank G, Schaps D:Treatment of extensive aortic aneurysms by a new multiple-stage approach. J Thorac Cardiovasc Surg 9 5 1 1,1988. 6. Svensson LG, Crawford ES, Hess KR, et al: Dis-
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section of the aorta and dissecting aortic aneurysms: Improving early and long- term surgical results. Circulation 82:lV-24, 1990. 7. Crawford ES, Coselli JS, Svensson LG, et al: Diffuse aneurysmal disease (chronic aortic dissection, Marfan, and mega aorta syndromes) and multiple aneurysm: Treatment by subtotal and total aortic replacement emphasizing the elephant trunk technique. Ann Surg 21 1:521,1990. 8. Svensson LG, Crawford ES: Aortic dissection and aortic aneurysm surgery. Clinical observations, experimental investigations and statistical analyses. Curr Probl Surg 1992; (In press). 9. Svensson LG, Crawford ES, Hess KR, et al: Deep hypothermia with circulatory arrest: Determinants of stroke and early mortality in 656 patients. J Thorac Cardiovasc Surg (In press). 10. Steen PA, Newberg L, Milde JH, et al: Hypothermia and barbiturates: Individual and combined effects on canine cerebral oxygen consumption. Anesthesiology 58527,1983. 11. Svensson LG, Crawford ES, Hess KR, et al: Composite valve graft replacement of the proximal aorta: Comparison of techniques in 348 patients. Ann Thorac Surg 54:427,1992. 12. Svensson LG, Crawford ES,Coselli JS, et al: The impact of cardiovascular operation on survival in the Marfan patient. Circulation 8O:l-233,1989. 13. Crawford ES, Svensson LG, Coselli JS, et al: Surgical treatment of aneurysm and/or dissection of the ascending aorta, transverse aortic arch, and ascending aorta and transverse aortic arch: Factors influencing survival in 717 patients. J Thorac Cardiovasc Surg 98:659,1989. 14. Kouchoukos NT, Marshall WG, Wedige-Stecher TA: Eleven-year experience with composite graft replacement of the ascending aorta and aortic valve. J Thorac Cardiovasc Surg 92:691,1986. 15. Svensson LG: A simple approach for the insertion of an aortic composite valve graft with minimal blood loss. Ann Thorac Surg 54:376,1992. 16. Svensson LG, Hess KR, Coselli JS, et al: A prospective study of respiratory failure after high-risk surgery on the thoracoabdominal aorta. J Vasc Surg 14:271,1991. 17. Crawford ES, Svensson LG, Coselli JS, et al: Staged repair of diffuse aneurysm of aorta using “elephant trunk” principle for ascending and arch replacement. Presented at the Society for Thoracic Surgery Meeting, San Francisco, 1991. (In press).
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ABSTRACT Replacement of the aortic arch during repair of either extensive aortic aneurysmal disease or aortic dissection can be a major undertaking. Borst introduced an “elephant trunk” technique whereby a tubular aortic graft prosthesis was inserted into the distal aorta while repairing the ascending aorta and aortic arch. The distal elephant trunk prosthesis was then used for a second stage operation that involved replacement of sections of the distal aorta. Since then, a few problems have been encountered with the standard elephant trunk procedure and this has led to a modification of the elephant trunk technique, which enables a more accurate and secure distal aortic arch anastomosis to be performed. Using the standard technique described by Borst, the surgeon has to suture in the groove between the tubular graft and the aortic wall, which can increase the risk that torsion on the suture needle will tear the aortic wall resulting in aortic rupture. Indeed, this complication has been noted in the postoperative period when performing the standard technique. Subsequently, the technique was modified with inversion of the graft in itself, placement of the graft in the descending aorta, and performance of the distal anastomosis using a technique similar to that described by Griepp. This has improved the ease of performing the procedure and the results of the technique such that a better than 90% survival rate can be expected for the first and the second stage repairs.
aorta, aneurysm, dissection, arch
The most critical step in the successful repair of extensively diseased aortas is replacement of the aortic arch. In this article, the technique of aortic arch replacement using a modified elephant trunk method as a first step for extensive aortic arch repairs is described in detail with comments concerning ancillary procedures. Address for correspondence: Lars G. Svensson, M.D., Department of Surgery, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030.Fax: (713)790-0202.
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Aortic arch repla ement using cerebral perfusion was first described by DeBakey and colleagues‘ in 1957. Subsequently, in 1963 Barnard and Schire2 described the first series of replacements of the aortic arch for aortic dissection and degenerative disease in which they used deep hypothermia with circulatory arrest. Later, Griepp and colleagues3 popularized the routine use of deep hypothermia and circulatory arrest for the repair of aortic arch repairs and
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described a technique of performing the distal aortic anastomosis with the graft inverted in the descending thoracic aorta. Replacement of varying extents of the aorta from the coronary artery ostia to below the mid descending aorta remained a difficult problem. To obviate this, Borst et alP95described a dual staged technique by which the ascending aorta and aortic arch were replaced first, leaving a segment of distal tubular graft in the descending thoracic aorta. Borst coined this procedure the “elephant trunk” techniq~e.4~5At a second stage, the distal aorta was repaired beyond the subclavian artery. As is often the case with cardiovascular operations, the operative technique evolves and is modified over time; similarly so has the method of performing the “elephant trunk” procedure over time. The author proposed the modified inversion technique and placement of the graft in the descending aorta in a female patient undergoing an elephant trunk repair under the auspices of Dr. Cosgrove at the Cleveland Clinic in March 1987. Subsequent to the successful elephant trunk repair, the technique was adopted by Dr. Crawford and the author, and has been used in a large number of patients using a distal aortic anastomotic technique similar to that described by Griepp et al.3 Rationale
A serious problem noted with the standard elephant trunk technique was that some patients undergoing the surgery suffered torn aortas at the distal suture lir1e.6~7In these patients, the aorta would rupture into the left chest just beyond the left subclavian artery at the distal suture line with resultant exsang~ination.6~7 The reason for the fatal complication was that a tubular graft was being sutured within the closed confines of another outer tube, namely the aorta. Therefore, this sometimes resulted in tearing of the aortic wall because of the great tension exerted on the wall by the needle during suturing at a difficult angle. In addition, the circulatory arrest period was prolonged with the attendant risk of postoperative neurological deficits. The modified technique, briefly described previously,6,7 of inverting the proximal part of the graft into the distal graft and placing it in the descending
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thoracic aorta resulted in easier suturing of the graft into position at the subclavian artery with a concomitant improvement in results, particularly for those patients with aortic dissections in whom the operative mortality rate for the modified elephant trunk technique has been reduced to only 5%. Apart from simplifying the insertion of the prostheses, the technique enables a greater surface contact area between the graft and the aortic wall after the inverted tube graft is withdrawn for the aortic arch replacement.When the graft is sutured into position, the graft is doubled over on itself. When it is unfolded by withdrawing the inner tube as shown in the figures, the suture is pulled taut since it is now wrapped around approximately twice as much as the distance of the graft. This is analogous to a rubber band around a book that gets stretched to twice its length by opening the book. This increased surface area and tightening of the suture line results in a reduced risk of bleeding at the distal anastomosis. Since it is easier to suture the distal anastomosis as shown by Griepp et al.3 with the graft inverted in the descending thoracic aorta, there is no need for torsion on the needle to suture through the graft and the aortic wall within the confines of the crevice between the graft and aortic lumen. Thus, the risk of tearing of the aorta is considerably lessened. In summary, the modified technique described in this article is the author’s preferred method of performing the procedure based on the evolution of the original technique reported by Borst and thereafter successfully applied by Cosgrove and Crawford using a distal anastomotic technique similar to that described by Griepp. Using the technique described next, the aortic arch can be replaced within a circulatory arrest period of approximately 30 minutes with a reduced risk of bleeding at the distal anastomosis and at the aortic arch anastornotic sites. METHODS
Operative preparation and anesthesia
The elephant trunk procedure is indicated for those patients who have combined diseases of both the ascending aorta plus aortic arch segments and in the distal aorta, namely either des-
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cending or thoracoabdominal aneurysm segments. A further second stage procedure will be required after the aortic arch has been repaired. The procedure can also be used for patients with type I aortic dissection in whom it is expected that the proximal descending and thoracoabdominal aorta will dilate with time. In these cases, an elephant trunk in the descending aorta will considerably simplify the second stage procedure. Preoperatively, patients undergo computerized axial tomograms to assess the extent and size of the aneurysmal disease and aortography for delineation of occlusive disease and planning of the operative procedure. A 24-hour Holter ECG examination, echocardiogram with color Doppler spectral analysis, and pulmonary function tests are routinely obtained. Cardiac catheterization of the coronary arteries and left heart ventriculogram are obtained whenever feasible. Anesthesia is conducted for the first stage and second stage procedures using bilateral radial artery cannula; at least two large-borevenous infusion cannulas; Swan-Ganz monitoring with mixed venous oxygen saturation monitoring; and, on occasion, right-sided cardiac indices with a right heart ventricular function catheter. When available, transesophageal echocardiography (TEE) is useful to monitor perfusion of the ascending aorta and aortic arch during cooling and to ensure that, at the end of the procedure, both aortic dissection lumens are perfused by the distal end of the elephant trunk. When time allows, preoperative autologous blood, plasma, and platelets should be obtained for intraoperative transfusion. At least 20 units each of red blood cells, fresh frozen plasma, and cryoprecipitate should be available for transfusion if required. One L of plasma-pharesed, platelet rich plasma is extracted from the patient as soon as possible after the induction of anesthesia. Patients are cooled until the electroencephalogram (EEG) shows no activity at 5-@Vsensitivity for 5 minutes, and bladder, rectal, nasopharyngeal, and esophageal temperatures are all below 20OC.8 The head of the patient is also surrounded by ice packs. More recently, retrograde perfusion of the superior vena cava by oxygenated blood from a Y arm off the arterial
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line has been used to perfuse the brain in 35 patients at our institution. This approach, however, is still too new to fully assess the results. The alpha-stat method of pH control during cardiopulmonary bypass is adhered to, i.e., the cold blood pH is not corrected to normal body temperature (37OC) and is maintained at pH 7.4W Prior to circulatory arrest, 5 mg/kg of sodium thiopentothal is administered intravenously in the event that there might be residual electrical activity.10 Steroids are not used since in a retrospective review (unpublished data), patients did not appear to benefit from 2 g of intravenous methyl prednisone. Furthermore, the risks of sepsis and multiple organ failure appear to be increased in patients who have received high doses of steroids. Operative technique The operative technique for repair of aortic dissections, ascending aortic arch aneurysms including the use of composite valve grafts, and Marfan syndrome have been reported)'-13 The technique for replacement of the aortic arch will be described. The femoral artery and vein are exposed in the groin, usually the right since it is less likely to be dissected, and then the vessels are looped with umbilical tape. The chest is opened through a standard midline incision and the pericardium opened. For those patients who previously had multiple cardiac operations or who have extensive aneurysms eroding the sternum, femoral artery-femoral vein bypass is instituted prior to sternal entry. In these instances, the patient is then cooled until EEG activity is absent, the circulation is arrested, and the sternum is opened. Two pump suction lines should be available in the event that the aneurysm is inadvertently opened. The aortic arch is exposed on its left anterior lateral surface to approximately 2 cm beyond the left subclavian artery. The plane of surgical dissection is kept close to the aorta to avoid damage to the phrenic nerve and to ensure that the left pleural cavity is not entered. Furthermore, electrocautery is avoided to reduce the risk of phrenic nerve damage. The vagus nerve and recurrent laryngeal nerves are preserved by dis-
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secting close to the aorta. The head vessels are not dissected out or mobilized since this causes unnecessary bleeding, and they are well visualized from inside the aorta. The patient is placed in a steep Trendelenburg position to prevent air accumulating in the arch vessels. Depending on the size of the aorta, a 23- to 30mm woven Dacron tubular prosthesis is selected for insertion and a 10-mm woven tube graft is selected for perfusion of the arch. These grafts are painted with a 25% solution of albumin with the grafts thoroughly stretched to ensure that the albumin fully penetrates the interstices. The prostheses are gently dabbed with a four-by-four sponge so that they are not excessively wet, and then a dry four-by-four sponge is placed internally in the aortic prosthesis, and the grafts flash sterilized for 5 minutes. This should result in a graft that is neither wet nor flaky, with the result that it will neither ooze nor result in embolization of albumin flakes to the brain. The four-by-four sponge is removed after baking the graft, and the 10-mm graft is anastomosed end-to-side to the larger aortic graft (Fig. 1A). To simplify anastomosing the tube graft to the aorta distal to the left subclavian artery, a staysuture is placed on the proximal end of the tube
graft. The suture and the proximal end are then inverted so that the proximal part with the adherent 10-mm side graft is invaginated into the more distal tubular graft (Fig. 1B). A hemostat is kept on the stay suture for later withdrawal of the inverted part of the tube graft. The end-to-side anastomosed 1O-mm tube graft is also inverted. The 10-rnm graft can easily be moved around during suturing without it obscuring the field. Furthermore, during removal of the inverted proximal end, the 1O-mm graft can also be gently tugged upon. Since the 10-rnm tube graft is already anastomosed to the aortic arch graft, the period of circulatory arrest is shortened. To save time prior to circulatory arrest, the anastomosis of the 10-mm graft to the proximal tubular graft should be performed and then inverted into the distal graft. The patient is placed on femoral arterial, and bicaval venous cardiopulmonary bypass after which atrioventricular venting and cooling are begun. During cooling, the ascending aorta and arch should be gently palpated at regular intervals to ensure that the measured radial arterial pressures correlate with the palpated pressures. The reason for this is to detect, particularly in those patients with aortic dissection, whether the
f
A
B
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Figure 1. (A) Inversion of the stay suture into the graft. (6) Inversion of the side arm into the graft.
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aortic arch vessels and brain are being adequately perfused. Although regular monitoring of the right radial artery pressure will usually alert the surgeon to the potential problem of an inadequate aortic arch perfusion pressure, this is not always the case. For example, the innominate artery may only be perfused by one lumen of the dissected aorta with no communication with the other lumen. Also, if the aortic dissection septum acts as a flutter valve, then selective nonperfusion of the head vessels can occur. Furthermore, solely monitoring the EEG without taking other factors into consideration may be unreliable because the EEG may show no brain activity, suggesting that hypothermia is adequate when, in fact, the cause is brain ischemia. The nasopharyngeal and esophageal temperatures should usually decrease more rapidly than the rectal and bladder temperatures. Indeed, a failure of esophageal and nasopharyngeal temperatures to adequately and rapidly fall should alert the surgeon to check forthe problem of nonperfusion of the head vessels. When the palpated pressures are normal and the EEG shows no electrical activity, then cardiopulmonary bypass is stopped and the patient is placed in a steep Trendelenburg position with circulatory arrest. The aneurysm is opened be-
tween two stay sutures and all blood is evacuated by pump suction and the left atrioventricular sump drainage (Fig. 2A). Hyperkalemic blood cardioplegia at 4OC in addition to topical hypothermic saline solution without ice are used for arresting cardiac contraction. After administration, topical hypothermic saline is removed from the pericardial well because it runs into the operative field and increases the risk of phrenic nerve damage in association with deep hypothermia. The aorta is opened along the arch and a stay suture is placed through the aorta proximal to the innominate artery (Fig. 2B). The incision is then continued to the right and then transversely across the back of the aorta at the level of the right pulmonary artery, completely transecting the aorta (Fig. 25). Distally, the aortic incision is taken to an anterior lateral position above the subclavian artery origin. In those patients with chronic aortic dissection, the septum is excised as far as possible in the descending thoracic aorta so that true and false lumens are perfused distally by the elephant trunk. To check that the elephant trunk does not preferentially perfuse only one lumen, an intraoperative TEE is useful to show that both lumens are perfused. In patients with acute dissection, replacement
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Figure 2A. Incision and opening of the ascending aorta and arch.
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Figure 2C. Placement of the inverted aortic graft into Figure 2B. Pansection of the ascending aorta and
the descending thoracic aorta.
aortic arch. Note stay sutures for retraction.
of the entire aortic arch is usually avoided. The exceptional cases include when the aorta is aneurysmal; rupture has occurred in the arch; and the descending thoracic aorta is aneurysmal and needs to be replaced at the same time because of severe back symptoms suggesting impending rupture of the descending thoracic aortic. In such patients, a Carrell patch from the aortic arch is mobilized. A matching piece of Teflon patch is then cut with an inner hole (doughnut shaped) to fit the greater vessels. Next, the Carrell patch is threaded through the Teflon doughnut opening and secured by a few interrupted sutures to sandwich the layers.G,* The inverted graft is placed in the descending aorta and a secure suture is performed just beyond the subclavian artery between the aorta and the doubled over edge of the tube graft (Figs. 2C and 3). The virtue of this procedure is that a hemostatic suture is inserted without undue torsion on the aortic wall. Furthermore, when the inner tube graft is pulled out, the suture line is automatically tightened due to unfolding at the suture line and the contact surface areas at the
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\? Figure 3. Suturing of the graft into position at the left subck~vianartery
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anastomosis are increased (Fig. 4A). Ticron 2-0 pledgeted, horizontally placed valve sutures (Davis & Geck, Wayne, NJ, USA) are used to further strengthen the anastomosis prior to everting the inner tube. After completion of the anastomosis, the stay suture and side arm are gently tugged upon to remove the inverted proximal graft from the distal elephant trunk and the arch vessels are then ready to be reanastomosed (Figs. 4B and 4C). Next, an oval hole is cut in the graft opposite the arch vessels. Reattachment of the arch vessels is then performed (Figs. 48 and 4C). While the patient is kept in a steep Trendelenburg position, the cardiopulmonary bypass pump is slowly restarted through the femoral artery cannula. Any potentially embolic material in the initial blood return is suctioned from the arch, and the greater vessels are allowed to fill. Gentle compression of the vessels ensures that no air pockets are present. The blood is allowed to exit through the proximal aortic graft and from the 10-mm side arm. When the return is free of air or any possible emboli, the other arterial arm of the cardiopulmonary bypass pump is connected to the 10-mm side arm (Fig. 5). All air is carefully evacuated from the aortic graft and 10mm side arm. The descending aorta is usually not punctured to aspirate air because if it is aneurysmal, this can result in severe hemorrhage that can be difficult to control if the aorta tears. Furthermore, if blood has not been completely evacuated from the descending thoracic aorta beyond the anastomosis and blood flow to the brain is reestablished via the side arm on the aortic arch, the risk of air embolization to the brain appears to be minimal. It should be noted that blood is not pumped from the femoral artery without the graft being undamped so that no air is inadvertently embolized to the brain. A plastic band should be applied to secure the position of the cannula in the side arm (Fig. 5). The proximal aortic tube graft is then clamped, and cardiopulmonary bypass is restored to normal flow and warming commenced (Fig. 5). The aortic graft at the highest point above the innominate artery but proximal to the clamp should be punctured with a needle a couple of times to allow any possible air in the graft to escape. Unless retrograde cerebral perfusion is being used or if no valve or coronary artery bypasses are
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needed, then blood in the cardiopulmonary bypass pump should be warmed prior to restarting cardiopulmonary bypass. The ascending aorta is replaced by completely transecting the aorta, just above the coronary artery sinuses, and performing a running suture without using Teflon felt6.8 (Fig. 5). By abandoning the inclusion technique, particularly the Bentalt composite valve graft technique for proximal anastomosis, the incidence of false aneurysms is reduced, including those patients with aortic dissection and Marfan syndrome.1’-14 For composite valve graft replacements, the preferred methods should be either reanastomosing the coronary arteries as buttons containing the ostia or using the modified Cabrol technique of an interposed Dacron tube graft to bridge the gap between the coronary artery ostia.11 This latter procedure allows for the insertion of the composite valve graft conduit without imposing undue tension on the coronary anastomoses. An alternative technique is to place a single tube graft to the left main coronary artery and use the button technique for the right coronary artery as previously described.15 Occasionally in a patient with acute aortic dissection in whom the coronary arteries cannot be reattached, the ostia need to be oversewn and distal coronary artery vein bypasses to the coronary arteries performed as necessaryW11 It is important to ensure that hemostasis is achieved at all the anastomoses prior to discontinuing cardiopulmonary bypass, and this is conveniently done during rewarming of the patient. After administration of protamine, the plasmapharesis concentrate is reinfused, and every 20 to 30 minutes, blood samples are sent for coagulation analysis to guide the administration of blood products until all clotting deficiencies are corrected or bleeding has stopped. During the postoperative period, the patient is treated, if necessary, with inotropes, vasodilators, and blood products. The standard postoperative care is similar to that for any patient undergoing cardiopulmonary bypass and coronary artery bypass. Blood products, however, should be used liberally i f there is any evidence of excess bleeding and, thus, any deficiencies in the coagulation profile are corrected to normal. Since these patients are usually fluid overloaded by the end
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Figure 4. (A) Removal of the inner tube graft and side arm from the distai aorta. (6 and C) Anastomosis of the arch vessels to the opening in the aortic graft.
of the procedure, dopamine is used liberally, as is LasixR (Hoechst-Roussel Pharmaceuticals Inc., Somerville, NJ, USA), to encourage diuresis. An AmicarR (alpha aminocaproic acid [Lederle Laboratories, Wayne, NJ, USA]) intravenous drip is also used in most patients at 1 to 2 g/hour for 6 hours after the initial loading dose of 5 g. Within an interval of 6 weeks to 3 months, the
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patient is readmitted for the second stage of the elephant trunk procedure. The use of the elephant trunk technique has simplified the second stage operation as a proximal indurated aorta does not have to be mobilized or crossclamped, and often, especially with descending thoracic aortic aneurysms, only one distal anastomosis is required. Whenever possible, segmental intercostal and lumbar arteries from
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Figure 5. Reestablishment of blood flow to the brain and completion of the proximal anastomosis.
vertebral levels F8 to L-2 are reattached to enable reestablishment of blood flow to the spinal cord by the artery of Adamkiewicz and higher thoracic spinal radicular arteries. The operative technique for the second stage procedure is essentially the same as that for the standard descending thoracic or thoracoabdominal aortic aneurysm repairs as described previously.6.8 The patient is placed in a left thoracotomy position with the pelvis tilted to approximately 60° to the table, depending on how low a position on the aorta the distal anastomosis is going to be performed. Both groins are prepared in the sterile operative field in the event that the femoral arteries need to be cannulated for pump bypass. The chest is opened through a standard thoracotomy incision unless the abdominal part of the aorta also needs to be replaced (Fig. 6, panel 1). For replacement of the abdominal section of the aorta, the incision is directed toward the umbilicus (Fig. 6, panel 2). This is in contrast to the usual thoracic incision along the ribs because at the angle formed at the junction of the abdominal midline incision and the thoracotomy incision, the lower skin flap tends to necrose,
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resulting in a large defect. The sixth rib is resected, and if more exposure of the aorta is needed at the subclavian artery, the fifth rib can be divided posteriorly, although this is rarely necessary for second stage elephant trunk procedures. The subcostal margin can be divided and the diaphragm preserved for repairs above the celiac artery, although for aneurysms extending below the superior mesenteric artery, division of the diaphragm is usually necessary. Either an extraperitoneal or intraperitoneal approach to the abdominal aorta can be used since there appear to be no differences in the incidence of respiratory complications according to a prospective study of respiratory failure.le The aorta at the site of the distal anastomosis is mobilized and encircled but no umbilical tapes are passed around it. The site of the previous distal elephant trunk anastomosis is identified immediately beyond the left subclavian artery and then the anterior lateral aorta is longitudinally opened with a scalpel. The thrombus surrounding the distal elephant trunk will usually enable the surgeon to identify the graft without the loss of blood, after which the graft is encircled and clamped (Fig. 7A). If bleeding should occur upon
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Figure 6. Incisions for second stage descending thoracic aortic or thoracoabdominal aortic repair.
i
i
Figure 7A. Clamping of the elephant trunk in the descending thoracic aorta.
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MODIFIED ELEPHANT TRUNK PROCEDURE opening the aorta, the graft can be quickly clamped. Since the possibility exists of the patient exsanguinating during this maneuver, it is advisable to have two autotransfusion devices available for aspirating blood and venous access sufficient for rapid reinfusion of blood. The blood does not need to be washed as long as protamine is administered at a later stage to reverse effects of the heparin mixed with the blood during suctioning. The distal anastomosis is performed either to the circumferentially transected aorta in a standard manner or to an interposition graft if the elephant trunk is not long enough to bridge the gap to the distal aortic anastomosis (Fig. 78). RESULTS
The elephant trunk operative technique has been used in 84 patients with a 30-day survival rate of 92%.9,’70f the patients surviving surgery, 56 patients have undergone second stage op-
erative procedure with a 30-day survival rate of 96%P.17 The median interval between procedures was 62 days with a range of 0 (second stages done immediately after the first stage procedure) to 358 days. Two of the initial deaths from the first procedure were due to rupture at the distal suture line in patients who underwent the procedure using the standard technique, but this has not been a problem using the modified elephant trunk technique in 1988. The net result is that nine patients had replacement of the entire (total) aorta; 27 had replacement of the ascending aorta, aortic arch, descending thoracic aorta, and upper abdominal aorta; and 22 patients had the entire thoracic aorta replaced. Seven of the 84 patients died within 30 days of the elephant trunk procedure. Four deaths were the result of ruptures in the distal aneurysmal aorta (two at the distal elephant trunk anastomosis at the subclavian artery as noted previously), one death was due to multiple organ failure, one to stroke, and one to respiratory failure. One patient
interposit io n g raft Figure 78. Insertion of the interposition aortic graft for completion of a thoracoabdominal aortic repair, resulting in the entire aorta being replaced. Note reattachment of intercostal arteries and visceral vessels. For repairing short descending thoracic aortic aneurysms, an interposition graft is usually not necessary and only one anastomosis is required with the distally transected aorta.
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developed permanent paraplegia after the elephant trunk procedure, and two developed paraparesis. This was probably due to the distal elephant trunk in the descending aorta being too long with the formation of thrombus around the graft, and occlusion of critical intercostal arteries
supplying the spinal cord.7 In conclusion, although patients who present with aortic aneurysmal disease requiring replacement of the ascending aorta, aortic arch, and distal aorta have to undergo extensive and high-risk surgery, with the technique described, a survival rate of 90% to 95% can be expected. This includes similar survival rates for the second stage procedure, resulting in a reasonable quality of life after this type of surgery and a reduced risk of death due t o rupture. This type of salvage surgery is recommended in those patients who are good-risk candidates for undergoing extensive aortic surgery. Acknowledgments: The author gratefully acknowledges permission from Dr. Cosgrove and Dr. Crawford to present this technique and from whom the author learned invaluable technical points. Without their contributions, this technique would not have evolved. Marion Robinson, Ph.D., kindly edited the paper, and Carol Pienta Larson drew the figures.
REFERENCES 1. DeBakey ME, Cooley DA, Crawford ES, et al:
Successful resection of fusiform aneurysm of aortic arch with replacement by homograft. Surg Gyn Obstet 105:656,1957. 2. Barnard CN, Schire V: The surgical treatment of acquired aneurysms of the thoracic aorta. Thorax 18:101, 1963. 3. Griepp RB, Stinson EB, Hollingsworth JF, et al: Prosthetic replacement of the aortic arch. J ThoracCardiovasc Surg 70:1051,1975. 4. Borst HG, Walterbusch G, Schaps 0:Extensive aortic replacement using “elephant trunk” prosthesis. Thorac Cardiovasc Surg 31 :37, 1983. 5. Borst HG, Frank G, Schaps D:Treatment of extensive aortic aneurysms by a new multiple-stage approach. J Thorac Cardiovasc Surg 9 5 1 1,1988. 6. Svensson LG, Crawford ES, Hess KR, et al: Dis-
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section of the aorta and dissecting aortic aneurysms: Improving early and long- term surgical results. Circulation 82:lV-24, 1990. 7. Crawford ES, Coselli JS, Svensson LG, et al: Diffuse aneurysmal disease (chronic aortic dissection, Marfan, and mega aorta syndromes) and multiple aneurysm: Treatment by subtotal and total aortic replacement emphasizing the elephant trunk technique. Ann Surg 21 1:521,1990. 8. Svensson LG, Crawford ES: Aortic dissection and aortic aneurysm surgery. Clinical observations, experimental investigations and statistical analyses. Curr Probl Surg 1992; (In press). 9. Svensson LG, Crawford ES, Hess KR, et al: Deep hypothermia with circulatory arrest: Determinants of stroke and early mortality in 656 patients. J Thorac Cardiovasc Surg (In press). 10. Steen PA, Newberg L, Milde JH, et al: Hypothermia and barbiturates: Individual and combined effects on canine cerebral oxygen consumption. Anesthesiology 58527,1983. 11. Svensson LG, Crawford ES, Hess KR, et al: Composite valve graft replacement of the proximal aorta: Comparison of techniques in 348 patients. Ann Thorac Surg 54:427,1992. 12. Svensson LG, Crawford ES,Coselli JS, et al: The impact of cardiovascular operation on survival in the Marfan patient. Circulation 8O:l-233,1989. 13. Crawford ES, Svensson LG, Coselli JS, et al: Surgical treatment of aneurysm and/or dissection of the ascending aorta, transverse aortic arch, and ascending aorta and transverse aortic arch: Factors influencing survival in 717 patients. J Thorac Cardiovasc Surg 98:659,1989. 14. Kouchoukos NT, Marshall WG, Wedige-Stecher TA: Eleven-year experience with composite graft replacement of the ascending aorta and aortic valve. J Thorac Cardiovasc Surg 92:691,1986. 15. Svensson LG: A simple approach for the insertion of an aortic composite valve graft with minimal blood loss. Ann Thorac Surg 54:376,1992. 16. Svensson LG, Hess KR, Coselli JS, et al: A prospective study of respiratory failure after high-risk surgery on the thoracoabdominal aorta. J Vasc Surg 14:271,1991. 17. Crawford ES, Svensson LG, Coselli JS, et al: Staged repair of diffuse aneurysm of aorta using “elephant trunk” principle for ascending and arch replacement. Presented at the Society for Thoracic Surgery Meeting, San Francisco, 1991. (In press).
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