Prevention and management of ureteral injuries during aortic surgery.

Ureteral injury during aortic surgery may lead to life-threatening consequences. Unlike gynecologic or abdominal surgical procedures in which ureteral injuries more commonly occur, this type of iatrogenic injury may be particularly hazardous because of the presence of prosthetic graft material. Ureteral obstruction by extrinsic compression, from an anteriorly placed graft limb or retroperitoneal fibrosis, is the most commonly reported type of ureteral complication. In most vascular surgical series, direct ureteral injury occurs in less than 1% of cases, and ureteral obstruction occurs from 2% to 14% of aortoiliac reconstructions. Prevention of ureteral injury begins with an intimate knowledge of the anatomy of the ureter along its entire course from the abdomen to the pelvis, and a realization of possible anomalies. Recognition of an injury is the next key to a successful outcome. Intraoperative recognition of an injury may allow immediate repair with a high rate of success. There are many options for the management of ureteral injuries depending on the nature of the injury, the time of diagnosis, and the level of the ureter at which the injury has occurred. The authors review the anatomy and most common causes of ureteral injury during aortic surgery and provide a guide to appropriate surgical management of these injuries.     

Pilot study with air-automated sigmoid capnometry in abdominal aortic aneurysm surgery.

BACKGROUND: and objective Ischaemic colitis can be a serious complication after aortic surgery. The paucity of clinical symptoms makes its diagnosis particularly difficult and often delayed. Automated on-line tonometry is now proposed to monitor intestinal perfusion. This study was designed to assess the use of semi-continuous sigmoid-to-arterial [P(r-a)CO(2)] PCO(2) gap monitoring in aortic surgery to detect colonic ischaemia. METHODS: This prospective clinical study was realized at the University Hospital of Lille, France, including eight males scheduled for abdominal aortic aneurysm surgery. Intraoperative and postoperative P(r-a)CO(2) values were compared with conventional monitoring and colonic mucosa aspect performed by sigmoidoscopy 48 h after surgery. Haemodynamic variables, O(2) delivery (DO(2)), O(2) consumption (VO(2)), O(2) extraction (ERO(2)), lactate, P(v-a)CO(2), P(r-a)CO(2) were measured peroperatively and every 4 h during a 48-h postoperative period. RESULTS: Intraoperative P(r-a)CO(2) values increased significantly with the highest value (4.36 +/- 3.42 kPa) observed during aortic clamping when DO(2) was the most altered. P(r-a)CO(2) continued to deteriorate after surgery with the maximal values between 8 (4.79 +/- 3.85 kPa) and 12 (4.68 +/- 3.26 kPa) h after surgery. This peak was associated with a significant ERO(2) increase counterbalancing an increase of VO(2) whereas DO2 tended to decrease. P(r-a)CO(2) values began to decrease only at the end of the study. The highest values of P(r-a)CO(2) were registered in patients with the most altered haemodynamic variables, severe ischaemic colitis along with higher hospital lengths of stay. CONCLUSION: Taken together, these data suggest that regional and automated capnometry may be easily used non-invasively to detect peroperative intestinal ischaemia in aortic surgery.     

Intestinal ischemia complicating abdominal aortic surgery.

A 9-year experience with 2137 patients undergoing infrarenal abdominal aortic reconstruction was reviewed to determine both the incidence of intestinal ischemia and the clinical, anatomic, and technical factors associated with this complication of aortic surgery. A total of 24 (1.1%) patients had overt intestinal ischemia, documented by reoperation or endoscopic findings. Of these, colon ischemia occurred in 19 (0.9%) and small bowel ischemia developed in 5 (0.2%) patients. The incidence after elective operation for aneurysmal or occlusive disease did not differ, but patients with ruptured aneurysms and those undergoing reoperative procedures for total graft replacement were at higher risk. Preoperative angiography was most helpful in ascertaining risk. Ligation of a patent inferior mesenteric artery was the most common (74%) feature in patients with colon ischemia. With preexisting inferior mesenteric artery occlusion, impairment of collateral circulation was attributable to superior mesenteric artery disease, dissection or retractor injury, prior colon resection, or exclusion of hypogastric perfusion. Bloody diarrhea was the most frequent postoperative symptom and colonoscopy the most reliable means of diagnosis. One half of patients with colon ischemia required resection after late recognition of perforation. All cases of small bowel ischemia were related to superior mesenteric artery disease or injury or use of suprarenal clamping. The overall mortality rate was 25% but rose to 50% if bowel resection was required. Intestinal ischemia remains an infrequent but serious complication of aortic surgery. Despite a multifactorial cause, identification of patients at increased risk can lead to operative strategies to reduce its occurrence.     

Spinal ischemia following abdominal aortic surgery.

Serious spinal cord ischemia may follow infrarenal abdominal aortic surgery. Five cases are summarized and added to the 23 previously published cases in order to identify this syndrome, emphasize its importance, and draw attention to the possibility of spontaneous recovery which may occur. The multifactorial complex which comprises each patient's clinical picture clouds a precise and specific cause for paraplegia in these cases. However, neither hypotension, steal phenomena nor emboli are necessary for completion of the syndrome. The relevant spinal cord arterial anatomy indicates that the common anomalies which occur favor development of spinal cord ischemia in the arteriosclerotic population which requires aortic surgery. No means of prevention is possible at this time.     

Horseshoe and pelvic kidneys associated with abdominal aortic aneurysms

The preoperative recognition of the existence of horseshoe or pelvic kidney with abdominal aortic aneurysm would greatly facilitate the proper operative care of these patients. Preoperative intravenous pyelography should be done routinely in all patients with abdominal aortic aneurysms. The diagnosis of an associated horseshoe or pelvic kidney can usually be established by this simple test if it is properly interpreted. If these anomalies are demonstrated or suspected, an aortogram should be performed to establish the status of the arterial supply to the kidneys. Some of the anomalous blood supply to the kidneys may not be apparent even after the aortogram. If the aneurysm can be resected without compromising the blood supply to the isthmus, this should be done and the aortic graft tunneled behind the isthmus [4]. However, if the isthmus has a large blood supply from the aneurysm and if division of this blood supply renders the isthmus ischemic, then the isthmus should be excised. In patients with pelvic kidney, to reduce ischemia to the kidney, aortic clamping time should be reduced to a minimum by completely freeing the aneurysm and dividing all the related lumbar arteries prior to aortic clamping.     

腹腔镜盆腔手术致泌尿系脏器损伤的防治

目的总结腹腔镜盆腔手术致泌尿系脏器损伤的原因、处理方法及预防措施。方法回顾性分析26例因腹腔镜盆腔手术致泌尿系脏器损伤的临床资料,包括普外科直肠手术3例、妇科手术23例;输尿管损伤21例、膀胱损伤5例。结果术中及时发现泌尿系损伤者7例,分别经内置双J管、输尿管端端吻合、输尿管或膀胱修补处理,均一期愈合,无并发症发生。术后发现泌尿系损伤者19例,其中膀胱阴道瘘3例,行耻骨上经膀胱修补成功;输尿管损伤16例,2例行逆行插管置双J管、14例行开放输尿管膀胱再植术治愈。结论腹腔镜盆腔手术创伤小、疗效高,提高手术操作技巧、积累经验有利于减少并发症的发生。     

Leg ischemia following surgery for abdominal aortic aneurysm.

Resection of an abdominal aortic aneurysm was associated with intraoperative or postoperative leg ischemia in seven of 100 consecutive survivors of this procedure. Distal embolization of thrombus and debris is the apparent cause in the majority of cases (six). One case of stenosis at a graft-to-vessel anastomosis was identified. Early (intraoperative) thromboembolectomy averted tissue loss in four cases. The role of concurrent lumbar sympathectomy in ameliorating ischemic tissue loss is evaluated. Postaneurysmectomy leg ischemia may accompany other serious complications, particularly hypotension and renal failure.     

Surgical management for acute aortic dissection with organ ischemia

In a series of one hundred and one cases of surgical treatment for acute aortic dissection between January 1986 and September 1997, we evaluated 29 cases presenting with organ ischemia. These consisted of 23 cases of acute type A dissection (type A) and 6 cases of type B dissection (type B). Organ ischemia was diagnosed by (1) aortography, (2) a retrospective review of the history and (3) physical examination or laboratory data. The 23 surgical cases of acute type A dissection consisted of, coronary ischemia 8 cases, cerebral and spinal cord ischemia 9 cases, intestinal ischemia 3 cases, lower extremities ischemia 10 cases, and plural organs ischemia 8 cases. In the 6 cases of acute type B, we noted 4 intestinal ischemias and 2 lower extremities ischemias. The operative mortality rates when subdivided according to ischemic organ were: coronary ischemia 50%, cerebral and spinal cord ischemia 11%, intestinal ischemia type A 33%, type B 50%, and lower extremities ischemia type A 33%, type B 0%. The operative mortality rates, especially for patients presenting with acute myocardial infarction or intestinal ischemia, were relatively high. In cases of acute aortic dissection when organ ischemia occurred, we believed that it was necessary to perform early thoracic aortic repair and reconstruction of the ischemic organ.     

How to avoid cardiac ischemic events associated with aortic surgery.

Whereas there is some degree of coronary artery disease (CAD) in most patients undergoing vascular surgery, there is no consensus regarding how to avoid perioperative cardiac ischemic events. Although this edition of Seminars in Vascular Surgery is devoted to aortic surgery, it must be remembered that the incidence of adverse cardiac outcomes after infrainguinal operations is at least as great as after aortic procedures. Thus, much of the information discussed herein will be applicable to patients undergoing all varieties of vascular surgery. Numerous strategies exist for preoperative cardiac testing before vascular operations. These strategies range from routine evaluation before surgery to a "minimalist" approach, treating all patients as though CAD was present. Although advocates of various algorithms often are unwavering in their convictions, there are no randomized, prospective studies comparing different strategies for evaluation and management of patients with CAD undergoing vascular surgery. Potential adverse effects of evaluation and cardiac intervention should be considered before undertaking screening studies. The authors analyzed the adverse outcomes of preoperative cardiac evaluation and intervention before vascular operations in patients treated at the Denver Department of Veterans Affairs Medical Center. Of 153 patients undergoing vascular procedures, 42 had extended cardiac evaluations. Sixteen (38%) patients had untoward events related to this evaluation. Extensive cardiac evaluation before vascular operations can result in morbidity, delays, and refusal to undergo vascular surgery. The underlying indication for vascular operations and the local iatrogenic cardiac complication rates should be considered before ordering special studies. Several recent randomized, prospective studies have established that perioperative beta-adrenergic blockade is beneficial in vascular patients with CAD. Beta-Blocker therapy can reduce the risk of perioperative adverse cardiac outcomes by 55%. The Coronary Artery Revascularization Prophylaxis (CARP) trial currently underway is a multicenter, prospective comparison of invasive intervention for CAD versus best medical care in patients undergoing aortic and lower extremity vascular surgery funded by the Department of Veterans Affairs Cooperative Studies Program.     

The retroperitoneal approach to aortic surgery associated with horseshoe kidney.

The horseshoe kidney is a rare anomaly that can significantly complicate aortic surgery. A bulky isthmus, abnormalities of renal anatomy, and a variable blood supply associated with a horseshoe kidney can pose technical difficulties in terms of aortic reconstruction. The left retroperitoneal approach affords an excellent exposure of the abdominal aorta in patients with a horseshoe kidney without dividing the renal isthmus and avoids the risk of injury to a ureter in an anomalous location. This is a case report of a patient with a horseshoe kidney who underwent a successful repair of an abdominal aortic aneurysm by a left retroperitoneal approach.     

Assessment of colonic ischemia during aortic surgery by Doppler ultrasound.

Colonic ischemia, related to division of the inferior mesenteric artery during aortic surgery, can be a significant cause of postoperative mortality. Operative determination of collateral mesenteric blood flow during temporary occlusion of the inferior mesenteric artery by use of the Doppler ultrasound device was evaluated in 25 patients undergoing aortic reconstructive vascular procedures. In five patients, the evaluation confirmed arteriographic evidence of an occluded inferior mesenteric artery; however, collateral flow was audible at the base of the large bowel mesentery and serosal surface of the left colon. In the other 20 patients with patent inferior mesenteric arteries, temporary occlusion of the artery resulted in persistent audible collateral flow in eighteen. However, in the remaining two patients, temporary arterial occlusion resulted in loss of audible Doppler flow signals over the base of the mesentery and serosa of the left colon. Maintaining patency of the inferior mesenteric artery by proper placement of the aortic graft in one patient and reimplantation of the artery into the prosthesis in another resulted in a return of Doppler flow over the left colon. All patients did well post operatively. Our data suggest that the presence of audible Doppler flow over the base of the large bowel mesentery and serosal surface of the left colon may correlate with viability of the colon postoperatively. We recommend routine use of the Doppler ultrasound device to determine adequacy of collateral mesenteric blood flow in patients undergoing aortic reconstructive vascular procedures.     

Prevention of bleeding in aortic root surgery

Bleeding after aortic root replacement with a valved conduit may be problematic and difficult to control. A few technical details that may facilitate hemostasis in aortic root surgery are described.     

Preservation of the pelvic circulation during infrarenal aortic surgery

Paraplegia, ischemia of the colon, and gluteal necrosis are uncommon but devastating sequelae of surgery of the infrarenal aorta. These complications are ischemic in nature, secondary to the following technical maneuvers, individually or in combination: bilateral occlusion of the hypogastric arteries; division of a patent inferior mesenteric artery; or proximal end-to-end aortic to common femoral artery bypass grafting accompanied by stenosis of the external iliac arteries. The etiology of paraplegia after infrarenal aortic surgery is of particular interest since it now appears that it is more likely due to interruption of flow to lumbosacral branches of the hypogastric arteries supplying the conus of the spinal cord and/or to division of a low-lying ‘conus medullaris artery’ rather than to occlusion of the higher-lying great radicularis artery of Adamkiewicz. Knowledge of the pelvic circulation to the colon, buttocks, and terminal spinal cord allows the surgeon prophylactically to avoid or reconstruct critical branches during operations on the infrarenal aorta. While rare, severe complications cannot be completely eliminated; hopefully their incidence can be reduced by an understanding of their etiology.     

Prevention of spinal cord ischemia after thoracic aortic occlusion

Paraplegia has been a devastating and unpredictable complication following surgical procedures necessitating temporary occlusion of the thoracic aorta. This study was undertaken to investigate the effect of the pressure gradient between the aortic pressure distal to the occlusion and cerebrospinal fluid pressure (CSFP), defined as "Relative spinal cord perfusion pressure" (RSPP) on the development of ischemia to the spinal cord by using somatosensory evoked potentials (SEP). In 30 mongrel dogs, the thoracic aorta just distal to the left subclavian artery was occluded for either 30 or 120 minutes until SEP disappeared. RSPP was maintained at 20, 30 or 40 mmHg in each dog by adjusting the degree of occlusion of th aorta and/or changing CSFP by withdrawal of cerebrospinal fluid or injection of normal saline into the subarachnoid space. SEP were recorded as a cortical response to the electrical stimulation of bilateral peroneal nerves. SEP did not disappear for 30 or 120 minutes when RSPP was 40 mmHg. It would be concluded that 40 mmHg or higher of RSPP is necessary in order to prevent the spinal cord ischemia due to the temporary occlusion of the thoracic aorta.     

Nonocclusive mesenteric ischemia after aortic surgery in a hemodialysis patient.

We report a case of nonocclusive mesenteric ischemia (NOMI), which developed after grafting for a descending thoracic aortic aneurysm in a hemodialysis patient. On postoperative day 5, acute increases in serum enzyme levels developed. Emergency angiography revealed severe vasoconstriction in the superior mesenteric artery (SMA) and other splanchnic arteries. Therefore an infusion of papaverine hydrochloride was started into the SMA. Although serum enzyme levels decreased, metabolic acidosis occurred the next day. An emergency laparotomy revealed segmental diffuse necrotic small intestine and colon. Despite a resection of the small intestine and sigmoid colon, the patient died of septic shock several days later. NOMI is uncommon, but it is a catastrophic event that can occur after cardiovascular surgery. If intestinal gangrene is suspected, prompt mesenteric angiography and vasodilator therapy followed by exploratory laparotomy should be performed without delay.