Risk stratification and outcomes of transluminal endografting for abdominal aortic aneurysm: 7-year experience and long-term follow-up.

PURPOSE: To determine early and late outcomes of transluminal endografting (TE) in patients with abdominal aortic aneurysm (AAA), stratified by predicted risk of procedure-related mortality with conventional operation. MATERIALS AND METHODS: A retrospective study was conducted in consecutive risk-stratified AAA patients undergoing TE at a not-for-profit cardiovascular referral center from March 1994 through November 2000 with follow-up through February 2001. With use of conventional risk strata (0 = low, 1 = minimal, 2 = moderate, and 3 = high), predicted procedure-related mortalities were 0%-1% in stratum 0 (n = 40), 1%-3% in stratum 1 (n = 118), 3%-8% in stratum 2 (n = 116), and 8%-30% in stratum 3 (n = 31). Main outcome measures were: (i) TE procedural success, (ii) procedure-related mortality, (iii) major nonfatal complications, (iv) composite adverse outcome (ii + iii), (v) length of stay (LOS), (vi) freedom from AAA rupture, (vii) late survival, (viii) late complications, and (ix) endoleaks and their classification and management. RESULTS: Women were significantly less likely than men to qualify for and undergo endografting: 24 of 91 (26.4%) women underwent TE, compared to 281 of 684 (41.1%) men. Of 305 attempted TE procedures, 291 (95.4%) were successful, four (1.3%) were urgently converted to open repair, and 10 (3.3%) were aborted. Procedure-related mortalities occurred in eight cases (2.6%) overall and one of 40 (2.5%), one of 118 (0.8%), four of 116 (3.4%), and two of 31 (6.5%) cases for risk strata 0-3, respectively. Perioperative survivors were significantly younger than nonsurvivors (74.3 y +/- 9 vs 81.6 y +/- 5.1; P =.0087). Forty-six patients (15.1%) had major complications. Composite adverse outcome was worse for patients in stratum 3 than those in stratum 1 (P =.0296) and those in strata 0, 1, and 2 combined (P =.026). Procedure-related mortality declined with institutional experience, from 4% among the first 100 patients undergoing TE to 1% among the last 105. For strata 0-3, median LOS were 2, 3, 3, and 4 days, respectively. Seventy patients (22.9%) had 75 endoleaks, of which 30 necessitated additional procedures, 17 self-resolved, and 22 were untreated as of March 1, 2001. Five patients with endoleak died of unrelated causes. One late-onset type IA endoleak (26 mo) resulted in the only AAA rupture and death in the follow-up period among the 291 patients who underwent successful transluminal endograft implantation. Actuarial survival rates at 1 year after TE were 90.3% +/- 1.9% for the overall study group and 97.5% +/- 2.5%, 94% +/- 2.5%, 86.9% +/- 3.3%, and 81.3% +/- 7.7% for risk strata 0-3, respectively. At 5 years, overall actuarial survival was 69.6% +/- 6.1%. Thirty-eight late deaths were attributable to post-TE AAA rupture (n = 1), AAA rupture late after failed TE with no further treatment (n = 1), other cardiovascular disorders (n = 7), cancer (n = 15), other causes (n = 10), and unknown causes (n = 4). Late deaths occurred in risk strata 0-3 at the following rates: two of 40 (5%), 10 of 118 (8.5%), 16 of 116 (13.8%), and 10 of 31 (32.3%), respectively (stratum 0 vs stratum 3, P =.0017; stratum 1 vs stratum 3, P =.003). CONCLUSIONS: TE is safe and confers durable protection against AAA rupture in treated populations. Still, protection is not absolute in patients with endoleaks, because late AAA enlargement and even rupture can occur. Given current knowledge, technology, and practice, careful patient selection and close surveillance of patients after implantation of transluminal endografts is essential.

Endovascular-assisted versus conventional in situ saphenous vein bypass grafting: cumulative patency, limb salvage, and cost results in a 39-month multicenter study.

OBJECTIVE: In this retrospective multicenter study, the results of a minimally invasive method of endovascular-assisted in situ bypass grafting (EISB) versus "open" conventional in situ bypass grafting (CISB) were evaluated with a comparison of primary and secondary patency, limb salvage, and cost. METHODS: Enrolled in this study were 273 patients: 117 underwent CISB (42 femoropopliteal, 75 femorocrural) and 156 underwent EISB (41 femoropopliteal, 115 femorocrural). EISB was performed with an angioscopic Side Branch Occlusion system and an angioscopically guided valvulotome. All the patients underwent follow-up examination with serial color-flow ultrasound scanning. RESULTS: Both groups had similar comorbid risk factors for diabetes mellitus, coronary artery heart disease, hypertension, and cigarette smoking. The primary patency rates (CISB, 78.2% +/- 5% [SE]; EISB, 70.5% +/- 5%; P =.156), the secondary patency rates (CISB, 84.1% +/- 4%; EISB, 82.9% +/- 5%; P =.26), and the limb salvage rates (CISB, 85.8%; EISB, 88.4%; P =.127) were statistically similar, with a follow-up period that extended to 39 months (mean, 16.6 months; range, 1 to 40 months). In veins that were less than 2.5 to 3.0 mm in diameter, the EISB grafts fared poorly, with an increased incidence of early (12-month) graft thromboses (CISB, 10 grafts, 8.5%; EISB, 24 grafts, 15.3%). However, wound complications (CISB, 23%; EISB, 4%; P =.003), mean hospital length of stay (CISB, 6.5 days +/- 4.83; EISB, 3.2 days +/- 3.19; P =.001), and mean hospital charges (CISB, $25,349 +/- $19,476; EISB, $18,096 +/- $14,573; P =.001) were all significantly reduced in the EISB group. CONCLUSION: The CISB and EISB midterm primary and secondary patency and limb salvage rates were statistically similar. In smaller veins (< 2.5 to 3.0 mm in diameter), however, EISB is not appropriate because overly aggressive instrumentation may cause intimal trauma, with resultant early graft failure. With the avoidance of a long leg incision in the EISB group, wound complications and hospital length of stay were significantly reduced, which lowered hospital charges and justified the additional cost of the endovascular instruments. When in situ bypass grafting is contemplated, EISB in appropriate patients is a safe, minimally invasive, and cost-effective alternative to CISB.

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.

Hydrophilic surface modification of metallic endoluminal stents.

PURPOSE: Stainless steel endovascular stents are inherently thrombogenic so that thrombus accumulates on these devices, leading to acute vessel occlusion. A potential solution to this problem is stent surface modification with hydrophilic polymers, which might limit platelet adhesion and reactivity. METHODS: N-vinylpyrrolidone (NVP) and potassium sulfopropyl acrylate (KSPA) hydrophilic monomers were gamma graft polymerized onto 1 cm2 stainless steel slabs and 4 mm Palmaz stainless steel stents. Surface characteristics of modified and plain stainless steel stents were then investigated with contact angle and x-ray photoelectron spectroscopy measurements, and in vitro and in vivo platelet reactivity was assessed as 111Indium platelet accumulation expressed as counts/min/cm2. RESULTS: Surface modification of stainless steel slabs and stents with both NVP and KSPA hydrophilic polymers significantly reduced in vitro platelet adhesion (plain = 2249 +/- 723 counts/min/cm2, NVP = 428 +/- 156 counts/min/cm2, KSPA = 958 +/- 223 counts/min/cm2) and in vivo platelet accumulation after 1 hour of blood flow exposure (plain = 1407 +/- 796 counts/min/cm2, NVP = 426 +/- 175 counts/min/cm2, KSPA = 399 +/- 124 counts/min/cm2. In addition, platelet accumulation on modified stents indexed to plain stents was lowest in KSPA-modified stents (NVP = 79.3% +/- 31.7% of plain, KSPA = 51.2% +/- 36.2% of plain). Surface analysis confirmed surface grafting with both monomers, and SEM documented smoothing of the irregular surfaces of the stainless steel stents after grafting. CONCLUSION: Hydrophilic polymer surface modification of stainless steel stents decreases initial stent surface platelet accumulation, which may decrease the risk of vessel thrombosis associated with the use of these devices.

Effect of dopamine on renal blood flow and cardiac output.

OBJECTIVE: To characterize the relationship between changes in renal blood flow and cardiac output induced by dopamine, hypothesizing that at low doses renal blood flow changes more than cardiac output. DESIGN: Anesthetized swine had renal blood flow and cardiac output measured during either continuous dopamine infusions (2 to 8 micrograms/kg per minute) or bolus dosing (1 to 16 micrograms/kg), and increases in both were compared. Two different fluid protocols were compared using constant dopamine infusions. In the constant pulmonary capillary wedge pressure protocol, intravenous fluids were titrated to keep this parameter constant. In the other protocol, fluid therapy was held constant at 10 mL/kg per hour. RESULTS: With infusions, mean increases in renal blood flow and cardiac output were relatively equal. The maximum increase was 35% at 8 micrograms/kg per minute under the constant pulmonary capillary wedge pressure protocol, with no significant differences (P > .1) found between the change in renal blood flow and cardiac output at any dose in either protocol. With bolus dosing, renal blood flow increased significantly more than cardiac output at 1, 4, and 8 micrograms/kg (P < .05). CONCLUSION: Disproportionate increases in renal blood flow compared with cardiac output at low bolus doses show initial renal responses to be independent of cardiac output. The infusion data suggest that renal responses exhibit tachyphylaxis or that cardiac output slowly accommodates to decreased total peripheral resistance.

Limb-threatening ischemia due to multilevel arterial occlusive disease. Simultaneous or staged inflow/outflow revascularization.

SUMMARY BACKGROUND DATA: Limb-threatening ischemia due to severe multilevel arterial occlusive disease may require both inflow and outflow bypass to achieve limb salvage. Simultaneous inflow/outflow bypass has been advocated because the cumulative risks of separate staged inflow/outflow procedures can be avoided. However, the magnitude of complete revascularization is substantial; thus, the morbidity and mortality of simultaneous inflow/outflow bypass may be excessive. METHODS: The medical records of 450 patients undergoing lower extremity arterial reconstruction between 1988 and 1994 were retrospectively reviewed, allowing identification of 54 patients who had undergone simultaneous aortoiliac and infrainguinal bypasses. This group consisted of 38 men and 26 women (mean age: 64.7 years), with significant cardiac disease in 24, smoking history in 53, and diabetes mellitus in 15. Indications for surgery were limb-threatening ischemia in 48 (89%) and severe short-distance claudication in 6 (11%). Inflow disease was corrected by direct aortoiliac reconstruction in 28, whereas other extra-anatomic bypasses were constructed in 26. Outflow revascularization required infrainguinal bypass to the infragenicular arteries in 46 (below-knee popliteal: 21; tibial: 25), a concomitant profundaplasty in 26, and a composite bypass conduit in 14. RESULTS: Limb salvage was 97% at 30 days whereas morbidity/mortality were 61% and 19%, respectively. However, the majority of complications and deaths occurred in patients undergoing aortic inflow plus complex outflow procedures (profundaplasty and/or composite bypass conduits), in which the morbidity/mortality rates were 84.2% and 47.4%, respectively, compared with rates of 45.7% and 2.9% (p < 0.01) after all other inflow/outflow procedures. The increased difficulty of these complex procedures is reflected in the significantly greater blood loss and operative times (1853 mL and 10.0 hours) compared with similar values (1125 mL and 7.7 hours)(p < 0.01) for all other inflow/outflow procedures. CONCLUSION: Simultaneous inflow/outflow bypasses are effective and safe in patients with severe, multilevel arterial occlusive disease, except when a complex outflow procedure is needed in conjunction with direct aortoiliac reconstruction. In the latter setting, a staged procedure is recommended because it may be associated with less morbidity and mortality.

Radiation exposure from cervical spine radiographs.

Radiation exposure to hospital personnel during 41 cervical spine radiographs of 30 multiply injured patients was prospectively evaluated. A digital dosimeter was attached to the exposed torso of personnel applying upper extremity traction or managing the airway. Radiation exposure was measured during each radiograph. Any exposure of one or more milliroentgen was detectable. No radiograph resulted in a measurable radiation exposure. Multiple radiographs (up to five exposures) also did not register even the minimum recordable exposure, demonstrating that exposure is less than 1.0 mR per radiograph (P < .05). We conclude that hospital personnel, even those applying traction or managing the airway, are not at risk of significant radiation exposure at the time of cervical spine radiographs.

Continuous arteriovenous hemodiafiltration in postoperative and traumatic renal failure.

Management of acute renal failure (ARF) in surgical patients has relied on supportive measures including hemodialysis and peritoneal dialysis. An alternative technique currently available is continuous arteriovenous hemodiafiltration (CAVH-D). Records of 44 surgical patients with ARF who were treated with CAVH-D in our surgical intensive care unit from 1989 to 1992 were reviewed. Thirty-five patients underwent emergency operations, and 4 patients underwent elective operations. Thirty-three patients were hemodynamically unstable immediately prior to the institution of CAVH-D, making hemodialysis a contraindication. A total of 565 CAVH-D days with an average of 13 days per patient were evaluated. Seventeen patients survived, with recovery of renal function in 13 patients. Vascular access was obtained via 227 percutaneous femoral catheters and 4 Scribner shunts. Seven vascular complications occurred, including arteriovenous fistula, pseudoaneurysm, limb ischemia, femoral artery hemorrhage, and femoral vein thrombosis. Based on these data, we conclude that CAVH-D is a safe and effective alternative in surgical patients with ARF.

Vascular complications of continuous arteriovenous hemofiltration in trauma patients.

Continuous arteriovenous hemofiltration (CAVH) has recently become useful in the treatment of acute renal failure following trauma. It allows continuous volume removal and avoids the acute hemodynamic changes often seen with hemodialysis. To determine the risks of CAVH catheters, the records of trauma patients undergoing CAVH from August 1989 through May 1992 were reviewed. Of 4685 trauma patients, 29 developed renal failure requiring dialysis, with 26 managed with CAVH. Vascular access was obtained via 126 percutaneous 8F femoral arterial and venous catheters (64 arterial, 62 venous) and four Scribner shunts. There was a total of 309 CAVH-D days, with an average of 11.9 days per patient. Complications included one femoral arteriovenous fistula, one pseudoaneurysm, and one deep venous thrombosis, resulting in a 3.1% (2 of 64) arterial complication rate and a 1.6% (1 of 62) venous complication rate. The incidence of arterial complications compares with that of angiography, but complications were major and required surgery. Alternative techniques such as continuous venovenous hemofiltration may prove beneficial.

Progesterone receptors in the human heart and great vessels.

Progesterone receptors (PgR) were identified in 31 of 50 specimens of human (men and women) thoracic ascending aorta, internal carotid, coronary artery, and left atrial appendage. This was accomplished with a peroxidase-antiperoxidase immunocytochemical assay employing a highly specific monoclonal antibody to primate PgR. In the aorta, specific staining was seen in the nuclei of smooth muscle cells and endothelium of intima, media, and adventitia. In the myocardium, staining was localized to the nuclei of the myocardial fibers. In internal carotid and coronary arteries, PgR was localized to endothelial nuclei of intima, and in vascular channels within the atherosclerotic plaques. PgR was also visible in the smooth muscle cell nuclei of uninvolved media and intima and at the plaque periphery. In contrast, receptor was not identified in vessels of the human uterus, breast, prostate, kidney, or gastrointestinal tract. These findings suggest that the heart and great vessels are target organs for steroid hormones.