肾下型腹主动脉瘤患者开腹手术死亡率多因素分析

目的探讨影响肾下型腹主动脉瘤开腹手术死亡率的因素。方法回顾性分析我院1995～2006年102例择期行肾下型腹主动脉瘤切除并人工血管置换术患者的临床资料。结果患者择期手术的死亡率为6．67％（7／102）,术中死亡的主要原因是失血性休克．术后死亡的主要原因为多器官功能衰竭。心血管病并发症与术后死亡率呈正相关性（P〈O．05）。结论加强麻醉期循环系统管理,可减少手术死亡率,提高腹主动脉瘤手术的安全性。     

Clinical and experimental evaluation of aortic polytetrafluoroethylene grafts for aneurysm replacement

The aortic expanded polytetrafluoroethylene bifurcation graft has a unique taper design. This was studied in an in vitro model using hydrogen bubbles and colored dyes to assess its hemodynamic significance compared with a conventional nontapered graft model. Under conditions of nonpulsatile flow the only significant differences were seen with a high percentage of occlusions of one outflow limb. Clinical experience with this new graft for infrarenal aneurysm replacement was accumulated in 163 elective cases and 53 emergency cases. The results with this new graft were compared with those obtained in the same time frame with alternative Dacron grafts. No detrimental problems with the graft have appeared in its use up to 78 months following aneurysm bypass or replacement.     

Thoracovisceral segment aneurysm repair after previous infrarenal abdominal aortic aneurysm surgery

OBJECTIVE: Repair of thoracovisceral aortic aneurysms (TVAA) after previous open repair of an infrarenal abdominal aortic aneurysm (AAA) poses significant challenges. We sought to better characterize such recurrent aneurysms and to evaluate their operative outcome. METHODS: We reviewed the records and radiographs of 49 patients who underwent repair of TVAAs between 1988 and 2002 after previous repair of an AAA. Visceral artery reconstructions were completed with combinations of beveled anastomoses, inclusion patches, and side arm grafts. In 14 patients visceral endarterectomy was required to treat associated occlusive disease. Sixteen patients had cerebrospinal fluid drainage, and 10 patients had distal perfusion during cross-clamping. RESULTS: Patient mean age was 72 years, and 80% were men. Fifty-one percent of patients had symptomatic disease, and average TVAA diameter was 6.2 cm. Mean time between AAA and TVAA repair was 77 months. Twenty-six percent of aneurysms were restricted to the lower visceral aortic segment, 35% extended to the diaphragm, another 35% extended to the distal or middle thoracic aorta, and 4% involved the entire remaining visceral and thoracic aorta. The 30-day operative mortality rate was 4.1% in patients with nonruptured aneurysms and 50% in patients with ruptured aneurysms, for an overall mortality rate of 8.2%. Fifteen patients (30.6%) had major morbidity, including paresis in two patients and dialysis-dependent renal failure in five patients. At late follow-up, three patients required further aortic operations to treat additional aneurysms, and four patients had fatal aortic ruptures. Two-year and 5-year cumulative survival rates were 61% (+/-7.5%) and 37% (+/-7.8%), respectively. At univariate analysis, operative blood loss was the sole significant predictor of major morbidity (P <.023), and rupture (P <.030, P <.0001) and aneurysm extent (P <.0007, P <.0001) correlated with both operative death and long-term survival. Only aneurysm extent (P <.010, relative risk 37.3) remained a significant predictor of long-term survival at multivariate analysis. CONCLUSION: Elective repair of TVAAs after previous AAA repair can be performed with an acceptable level of operative mortality, though with considerable operative morbidity. Limited long-term survival mandates careful patient selection, and the high mortality associated with ruptured TVAA underscores the need for post-AAA surveillance.     

Single-stage surgery for distal aortic arch aneurysm and infrarenal abdominal aortic aneurysm through anterolateral approach.

A 58-year-old man with a distal aortic arch aneurysm (DAA) associated with an infrarenal abdominal aortic aneurysm (AAA) successfully underwent a single-stage replacement of the aneurysms. A left anterolateral thoracotomy was used for replacement of the DAA, which was performed using profound hypothermic circulatory arrest and continuous retrograde cerebral perfusion. An extraperitoneal approach in conjunction with a lateral abdominal incision was employed for replacement of the AAA. The combination of an anterolateral thoracotomy and a lateral abdominal incision is useful in combined surgery for DAA and AAA.     

Anaesthesia and critical care for scheduled infrarenal abdominal aortic aneurysm surgery

OBJECTIVES: Patient scheduled for infrarenal abdominal aortic aneurysm surgery carries a high risk of cardiac or respiratory comorbidity. To outline the perioperative management for these patients. METHODS: Review of the literature using MesH Terms "abdominal aortic aneurysm", "anesthesia", "analgesia" "critical care" and/or "surgery" in Medline database. RESULTS: Cardiac preoperative evaluation and management have recently been reviewed. Intermediate and high-risk patients should undergo non-invasive cardiac testing to decide between a preoperative medical strategy (using betablocker+/-statin and aspirin) and an interventional strategy (coronary angioplasty or cardiac surgery). Perioperative myocardial ischaemia should also be investigated by clinical, electrocardiographic and biologic monitoring such as plasmatic troponin Ic dosage. Specific score could also assess the respiratory failure risk preoperatively. Epidural analgesia decreases this risk. There is no evidence that a pharmacological treatment decreases the incidence of acute renal failure after aortic surgery. Endovascular repair is actually recommended for older, higher-risk patients or patients with a hostile abdomen or other technical factors that may complicate standard open repair.     

Lipid uptake in expanded polytetrafluoroethylene vascular grafts

Purpose: The mechanisms of vascular prosthesis failure are reported to be associated, in part, with an atherosclerotic degenerative process that is related to an abnormal lipid infiltration. The lipid uptake in expanded polytetrafluoroethylene (ePTFE) vascular grafts was reproduced in vitro, and the effect of time on the permeability of these prostheses was studied. Methods: Water permeability tests were carried out under dynamic flow conditions at various hydrostatic pressures. Lipid uptake was simulated by circulating a phosphatidylcholine suspension inside an expanded Teflon prosthesis under pulsatile or continuous transmural pressure ranging between 80 mm Hg and 180 mm Hg, at a flow rate of 500 mL/min and 2000 mL/min, for a duration ranging from 2 hours to 1 month. Results: Water permeability tests indicated that under hydrostatic pressures of 180 mm Hg and 300 mm Hg, water percolated through the prosthesis wall after an exposure of 720 minutes and 75 minutes, respectively. After exposing the prostheses to the lipid dispersion under the various flow conditions, the fluid convection through the wall occurred. Preferential convection pathways with a constant periodicity were observed across the length of each prosthesis and were, therefore, associated with regularly spaced perforations depicted in the structure of the devices. Phospholipids gradually agglomerated within the prosthesis wall, allowing a restrictive molecular mobility. Infrared spectroscopy results indicated that the lipid uptake depended on the transmural pressure and time of exposure. Conclusion: The occurrence of the membrane permeability may be associated with the dilatation and plastic deformation of the prosthesis. Lipid uptake occurs in ePTFE grafts after an aggressive kinetic process. (J Vasc Surg 1998;28:527-34.)     

Preliminary experience with expanded polytetrafluoroethylene grafts.

This early clinical experience of members of the New England Society for Vascular Surgery with expanded polytetrafluoroethylene (PTFE) grafts was evaluated. Questionnaires were distributed to 52 active members of the Society and 32 answers were received. A total of 186 graft insertions were evaluated, of which 112 were positioned in the lower limb; 106 grafts were inserted for libm salvage. Patency rates for femoral-popliteal bypass grafts were determined by life-table analysis. Our results show a 6 to 9 month cumulative patency rate of 91% for PTFE grafts with a popliteal anastomosis above the knee, and a 52% patency rate for below-knee anastomosis. Two complications, aneurysmal dilatation and graft sepsis, were noted in this series. The new graft material exhibits an early patency rate higher than bovine or Dacron grafts which warrants long-term use and evaluation.     

Longevity of expanded polytetrafluoroethylene grafts for superior vena cava

We previously reported that the expanded polytetrafluoroethylene (ePTFE) graft for superior vena cava (SVC) substitution presents the problems of flexion and kinking when the graft is long. We therefore replaced the SVC of dogs with two types of prosthetic substitutes, ePTFE (Gore-Tex) and spiral-supported ePTFE (Im/praflex), and evaluated the long-term patency of the prosthetic substitutes. Total replacement of the SVC was performed in 9 adult mongrel dogs. The substitutes were ePTFE and spiral-supported ePTFE in 5 and 4 dogs, respectively. The animals were killed about 3 years after replacement of the SVC, and the harvested specimens were histologically examined by light microscopy and scanning electron microscopy. Evaluation of ePTFE revealed late occlusion in 1 of 5 dogs. The spiral-supported ePTFE showed patency in all dogs. In the group with ePTFE grafts, light microscopic examination revealed abnormalities of endothelial cells, granulation, and necrosis. There was no hyperplasia of the subendothelial connective tissue near the center. In the animals with spiral-supported ePTFE grafts, the subendothelial connective tissue showed favorable growth even in the center of the reconstructed site. There was no granulation in the spiral-supported ePTFE group. Scanning electron microscopic examination in the ePTFE group showed that endothelial cells were spindle-shaped and had an irregular surface. The spiral-supported ePTFE group showed an almost regular form of endothelial cells and no abnormalities except for the slightly spindled shape in the center. Therefore, we recommend that spiral-supported ePTFE should be used as an SVC substitute in clinical situations.     

The fate of the infrarenal aortic neck after open aneurysm surgery

Purpose: The long-term success of the endovascular repair of abdominal aortic aneurysms is dependent on the secure fixation of the stent graft at the proximal and distal attachment sites. A progressive dilatation of the infrarenal neck may jeopardize this success. The data regarding this issue are scarce. However, the long-term fate of the infrarenal neck can be studied in patients who have undergone open aneurysm surgery. This was the purpose of the present investigation. Methods: Between January 1989 and December 1993, 64 patients underwent open repair of infrarenal abdominal aortic aneurysms. Of the 36 patients who were eligible for the study, 19 had preoperative computed tomography scans that were available. The 19 patients also underwent a new computed tomography scanning at a mean of 71 ± 12 months after surgery. Results: The mean preoperative aortic diameter was 25.4 ± 3.7 mm at the infrarenal neck, 24.8 ± 3.4 mm at the level of the renal arteries, and 26.7 ± 3.0 mm at the level of the superior mesenteric artery (SMA). The mean aortic diameter increased at all of the 3 levels: +2.8 ± 3.1 mm (P = .0014) at the infrarenal neck, +2.8 ± 3.0 mm (P = .0013) at the level of the renal arteries, and +1.3 ± 3.0 mm (P = .080) at the level of the SMA. The annual growth rate was 0.48 mm/y (P = .0023) at the infrarenal neck, 0.46 mm/y (P = .0010) at the level of the renal arteries, and 0.21 mm/y (P = .5811) at the level of the SMA. No correlation was found between the preoperative infrarenal neck diameter (r = .295, P = .2194), the preoperative aortic diameter at the level of the renal arteries (r = .302, P = .2088), and the preoperative aortic diameter at the level of the SMA (r = .314, P = .2043) and the corresponding growth rates. The patients were stratified into 2 groups—one with a small annual growth rate at the infrarenal neck (n = 11; ≤0.3 mm/y) and one with a larger annual growth rate (n = 8; >0.3 mm/y)—and no differences in the preoperative infrarenal neck diameter or the clinical characteristics were found between the groups. Conclusion: This investigation shows an aortic dilatation of the infrarenal neck and of the aorta at the level of the renal arteries of approximately 0.5 mm annually after open aneurysm surgery. This dilatation raises concern regarding the long-term success after endovascular repair. The data also indicate that 2 populations might exist with regard to the annual growth rate of the infrarenal neck—one with low growth rate and one with higher growth rate. This might be of interest for the future selection of patients for endovascular repair. (J Vasc Surg 1998;28:889-94.)     

Intraoperative recovery of blood in surgery of infrarenal abdominal aortic aneurysm

The aim of the study was to evaluate the possibility of reducing the blood loss during elective surgery for abdominal aortic aneurysms using particular intraoperative surgical expedients. From 1993 to 1999, 200 patients were recruited into the study. We performed 90 aorto-aortic, 84 aorto-bisiliac, 4 aorto-iliac-femoral, 12 aorto-bisiliac-hypogastric, and 10 aorto-bifemoral reconstructions. Several surgical techniques were used and are described in detail. The mortality rate was 3.5%. Haemoglobinaemia 24 hours after the operation had decreased by 2.5 +/- 0.9 g/dl. In 67% of cases the estimated blood loss was lower than 300 ml. There were no transfusions in 44% of cases, and autologous transfusions in 17%. The average estimated blood loss was 350 ml, with mean reinfusion of 0.98 blood units. Our study suggests the possibility (44%) of avoiding the use of blood transfusions thanks to intraoperative blood saving by means of particular surgical techniques.     

In vitro evaluation of electrostatic endothelial cell transplantation onto 4 mm interior diameter expanded polytetrafluoroethylene grafts

Purpose: To perform an in vitro evaluation of electrostatic endothelial cell transplantation of human umbilical vein endothelial cells (HUVEC) onto segments of 4 mm internal diameter expanded polytetrafluoroethylene (ePTFE) vascular prostheses. Methods: This evaluation consisted of exposing vascular graft segments that had been subjected to either electrostatic or gravitation transplantation with HUVEC to a physiologic shear stress (15 dynes/cm²) under steady flow conditions within a flow loop system. Biochemical assays were performed on freshly transplanted grafts by means of radioimmunoassay for prostacyclin and thromboxane A₂. Results: There was a 30% loss of HUVEC after 30 minutes of shear stress exposure from the grafts subjected to gravitational transplantation with no additional significant (α = 0.05) loss after 120 minutes. Grafts subjected to electrostatic transplantation had no significant (α = 0.05) loss of HUVEC during exposure to physiologic shear stress. Furthermore, after 120 minutes of shear-stress exposure, the grafts subjected to electrostatic transplantation (78,420 ± 6274 HUVEC/cm²) retained 2.3 times more HUVEC than the counterparts subjected to gravitational transplantation (34,427 ± 4637 HUVEC/cm²). The biochemical assay results indicated no significant (α = 0.05) production of prostacyclin or thromboxane A₂ regardless of the method of cell transplantation. Conclusions: (1) The electrostatic transplantation technique was superior to the gravitational transplantation technique in terms of cellular retention when the ePTFE grafts were exposed to physiologic shear stress. (2) Production of prostacyclin and thromboxane A₂ did not differ between transplanted HUVEC subjected to gravitational or electrostatic procedures. (J Vasc Surg 1998;27:504-11.)     

Conversion of failed endovascular infrarenal aortic aneurysm repair with fenestrated/branched stent grafts

Fenestrated and branched endovascular aneurysm repair (F/BEVAR) can be used to salvage infrarenal endovascular aneurysm repairs (EVARs) that fail secondary to inadequate proximal seal or progressive proximal aneurysmal disease. Extending the aneurysmal seal zone proximally can be performed without compromising flow to renal and visceral vasculature. Device planning requires adapting for prior endograft length and may involve a tubular or bifurcated design. Technical difficulties include navigating in the constrained space of the prior endograft and cannulating target vessels through suprarenal fixation devices. Strategies to optimize success include brachial/axillary access, use of diameter reducing ties, preloaded wires, and steerable sheaths. Reported technical success rates range from 85% to 99% and long-term freedom from re-intervention rates range from 67% to 83%. F/BEVAR in patients with prior EVAR, compared with those without, is associated with similar morbidity, mortality, and freedom from re-intervention, albeit with increased operative and fluoroscopic time. Compared with open surgery, F/BEVAR is associated with decreased morbidity and mortality. Alternatives to F/BEVAR treatment for inadequate proximal seal after infrarenal EVAR include open conversion, chimney/snorkel endografting, physician-modified endografting, balloon expandable uncovered stent, embolization, and endostapling.     

Extensible expanded polytetrafluoroethylene vascular grafts for aortoiliac and aortofemoral reconstruction

The operative experience and medium-term outcome achieved with longitudinally extensible ('stretch') expanded polytetrafluoroethylene (ePTFE) bifurcated grafts in patients undergoing aortoiliac or aortofemoral reconstruction for occlusive disease at our institution was reviewed. Between 1991 and 1998, 242 patients received a bifurcated stretch graft. Forty-one patients (17%) required an aortic endarterectomy, and 63 (26%) underwent femoral artery endarterectomy. 228 patients were followed for a mean of 32 months. One patient (0.4%) died perioperatively. The perioperative morbidity included cardiac (3.7%), respiratory (2.5%), and renal (3.3%) complications. Three patients required early reoperation for bleeding. Four (1.7%) grafts thrombosed within 24h of surgery; eight additional grafts (3.3%) thrombosed 5-8 months later. There were three postoperative aortic graft infections, one inguinal infection, three inguinal pseudoaneurysms, and one aortic pseudoaneurysm. Ultrasonography during follow-up showed no periprosthetic fluid collections or graft dilatations. The bifurcated ePTFE stretch graft is suitable for aortoiliac and aortofemoral reconstruction, and its physical characteristics may help to reduce graft-related complications.     

Minimally invasive vascular surgery for repair of infrarenal abdominal aortic aneurysm with iliac involvement

PURPOSE: A minimally invasive vascular surgery (MIVS) technique for repair of infrarenal abdominal aortic aneurysm (AAA) with iliac involvement was evaluated, and its outcome was compared with conventional open repair. METHODS: Twenty patients with AAA with iliac involvement underwent treatment with bifurcated graft replacement with the MIVS technique. The procedure was performed via minilaparotomy, with the incision length determined according to the extent of the AAA obtained with ultrasound scanning and with the small intestine confined completely within the abdominal cavity. The proximal and distal operating fields were obtained with changing the patient position and arranging for the abdominal incision to be retracted cephalad and caudad. Perioperative courses in these 20 patients (the MIVS group) were analyzed in comparison with 14 patients who underwent conventional open repair, which was performed through the full midline laparotomy with the intestine simply covered with moistened towels (the conventional group). RESULTS: The MIVS technique for AAA repair was performed with a mean abdominal incision length of 8.4 cm and a range from 6.5 to 11.2 cm. The patients in the MIVS group showed earlier resumption of oral intake and ambulation in comparison with those patients in the conventional group (liquid diet: 1.1 +/- 0.3 days versus 2.9 +/- 1.4 days; P <.01; solid diet: 2.0 +/- 0.2 days versus 3.9 +/- 1.4 days; P <.01; ambulation: 2.1 +/- 0.8 days versus 4.3 +/- 2.3 days; P <.01), with comparable mortality and morbidity rates. Accordingly, the patients in the MIVS group were discharged earlier (20.7 +/- 6.3 days versus 33.9 +/- 12.6 days; P <.01), and total hospitalization charges were significantly decreased (2,232,791 +/- 200,747 Japanese yen versus 2,640,441 +/- 243,889 Japanese yen; P <.01). CONCLUSION: The MIVS technique allowed earlier postoperative recovery with comparable morbidity and mortality rates with the conventional technique and, therefore, saved hospital stay length and total hospitalization charges. Thus, the MIVS technique is considered as a new and effective minimally invasive technique for open AAA repair.     

Inflammatory infrarenal aortic aneurysm with aortocaval fistula

This is a report of an open repair of an inflammatory infrarenal aneurysm with a large rupture into the vena cava. Preoperative imaging with contrast-enhanced computed tomography revealed the presence of the fistula and was an important aid in pre- and perioperative planning.     

Microvascular polytetrafluoroethylene (Gore-Tex) grafts in the infrarenal rat aorta

To evaluate the use of microvascular prosthetic grafts, the infrarenal aorta in 33 male Sprague-Dawley rats was replaced by an interposition graft of PTFE (polytetrafluoroethylene, Gore-Tex). Three groups of experimental animals were studied: Group A consisted of rats with 7-mm-long grafts, group B consisted of rats with 20-mm-long grafts, and group C consisted of rats with 20-mm-long grafts and ligatures of one patent after varying observation periods (6-92 days, median value 28 days, mean value 49 days). In group B all grafts but one (13/14) were patent (0-201 days, median value 198 days, mean value 118 days). In group C two grafts occluded immediately postoperatively, whereas the remaining six were patent (0-24 days, median and mean values 9 days). Twelve of 13 grafts observed for 3 months or more remained patent. There were no signs of infection. Angiography did not reveal any stenosis in the anastomoses of patent grafts. Light microscopy demonstrated a good adaptation between the grafts and the aorta in all animals. In the short grafts observed for 3 months and in the long grafts observed for 6 months, the luminal surfaces were completely covered by endothelial-like cells. In the occluded graft in group B, a stenosis was demonstrated in one of the anastomoses. This was not found in any other specimen. The results of this study document the possibility of using PTFE grafts of 1 mm diameter in experimental microvascular position.