Vascular and Endovascular Surgery

Immune-mediated heparin-induced thrombocytopenia (HIT) is a well-defined syndrome. Clinical criteria (thrombocytopenia, resistance to heparin anticoagulation, or thromboses during heparin therapy) are defined, and serologic diagnostic tests are available. Earlier recognition of HIT syndrome has allowed for significant advances in therapy, leading to marked reductions in morbidity and mortality from HIT syndrome. This review addresses the epidemiology, pathobiology, and management of HIT syndrome

Endovascular placement of vascular stent grafts in the aorta and peripheral vessels has become a prominent tool in the armamentaria of the vascular surgeon. Despite, several reports of stent graft infection, no current guidelines exist regarding the administration of antibiotics prior to episodes of potential bacterial seeding. We sought to clarify the role of prophylactic antibiotics in preventing stent graft infection after the parenteral administration of Staphylococcus aureus (S. aureus) at various intervals following device placement. A stent graft device was constructed from a 4 mm thin-walled polytetrafluoroethylene (PTFE) graft attached to the outside of a balloon expandable 394-Palmaz stent (Johnson and Johnson Interventional Systems, Warren, NJ). It was then inserted into the common iliac artery through an 1 IF peal-away sheath placed in the femoral artery. Sixty grafts were placed into 30 dogs. There were 5 groups of equal number (groups A-E). In group A, six dogs received intravenous injection of 3 cc X 104 CFU (colony forming units), biotype 31375 5. aureus, 1 day after stent graft implantation. An identically treated group B received antibiotic prophylaxis (1 gm cefazolin 30 minutes prior to bacterial challenge). Group C received bacterial injection 7 days after graft implantation with no antibiotic prophylaxis. Group D received bacterial injection 7 days after graft implantation with antibiotic prophylaxis. A control group E received no antibiotics and was not infected. All infected animals were sacrificed 7 days following bacterial challenge and the stent graft complex cultured. One half of the control group was sacrificed at 7 days and the other half at 14 days. The overall stent graft patency was 90%. Four of the six graft occlusions occurred in group A. Eleven of 12 (92%) dogs cultured S. aureus (biotype 31375) from the explanted stent graft complex. Two localized perforations occurred at the site of the infected complex. In group B, C, and D, no explanted graft complex cultured S. aureus. One graft occluded in group C and D. No stent graft in the control (group E) cultured S. aureus. A stent graft infection model can be consistently produced. In the canine model, the stent graft is more susceptible to infection in the early postoperative period and becomes less susceptible to bacterial seeding at one week after implantation. The authors recommend the use of prophylactic antibiotics in the prevention of endovascular graft infections in the early postoperative period during times when bacterial seeding may occur. They postulate that pseudointima formation during graft incorporation into the vessel wall may be responsible for the resistance to infection.

Presented are the experiences with 1,516 external valvular stents (Venocuff™ and Venocuff II™) implanted at the saphenofemoral junction (SFJ) between 1985 and 2000. To assess the applicability of the procedure it was found that the appropriate implantation was performed in 34% of 310 consecutive venous procedures. To assess patient preference between external valvular stenting and simultaneous contralateral stripping, 56 consecutive patients were followed up at 3 months postoperatively. Four percent preferred stripping, 4% had no preference, and 92% preferred Venocuff II™ implantation. Competence at the SFJ with specific duplex ultrasound indicators was 94% at 3 months (n= 100) and 90% at 4.8 years (n= 107). Minimal residual reflux (less than 50 mL/minute with maximum Valsalva) was present in the remainder but did not produce symptoms and very rarely progressed over the mean time of 5 years. The internal diameter (ID) of the long saphenous vein (LSV), 3 cm distal to the SFJ, changed from 7.6 ±2.3 mm to 4.9 ±1.1 mm (p<0.001) and at the knee from 6.9 ±1.9 mm to 3.7 ±1.0 mm (p<0.001). Patients presenting with underlying deep venous disease began with significantly higher ID, ie, 9.0 ±2.1 mm at the upper end of the LSV and 7.1 ±2.0 mm at the knee, but postoperatively the IDs reverted to those of postoperative patients with a normal deep venous system. To assess patients with recurrences, 366 limbs had simultaneous stripping and contralateral SFJ repair with the Venocuff II™. Of these 33 (9%) had recurrences at 4.9 years, 82% of them on the stripping side, and on the repair side half of the recurrences had a competent SFJ (9%). Limbs with an incompetent lateral or anterior accessory system, with an incompetent SFJ (168), were compared with 11 matched randomized controls where stripping was performed. The recurrence rate was 1.2% versus 36% on the strip side. The follow-up for these cases was 6.4 years. Pregnancy (n = 14) produces a high recurrence rate, but stripping and valve repairs were not significantly different, ie, despite small numbers, there was a very strong tendency toward higher recurrence rates on the stripped side. The complication rate was small and the cost of the device is low. The method allows a repairable nonablative approach that can be offered in patients where no other surgical treatment can or should be offered. External stenting to the SFJ is the preferred option for early to moderate varicose veins involving the LSV where the clinical and ultrasonic indicators have been fulfilled.

The objective of this study was to investigate the effect of infrarenal aortic cross-clamping and unclamping on gut mucosal perfusion by gastric tonometry and on sigmoid colonic tissue blood flow by laser Doppler flowmetry during abdominal aortic surgery. This was a prospective before-and-after intervention comparison study in a university hospital of 8 male patients, aged 57-87, undergoing elective infrarenal abdominal aortic surgery. Each patient was pretreated with ranitidine. Following general anesthesia, a nasogastric tonometer was inserted into the stomach. The balloon of the tonometer was filled with 2.5 mL of normal saline for gas tension and pH analysis. This process was repeated before and after aortic cross-clamping and unclamping. Gastric mucosal pHi was calculated with the Henderson-Hasselbalch equation from the arterial Hco₃ and the tonometrically measured mucosal Pco₂. A laser Doppler flow probe was placed in contact with the serosa of the sigmoid colon against the mesentery after the abdomen was opened. Sigmoid colonic tissue blood flow (SCBF) was assessed by the laser Doppler flowmeter. Gastric mucosal pHi by gastric tonometry and colonic tissue blood flow by laser Doppler flowmetry were measured before and after aortic cross-clamping and unclamping. Gastric mucosal pHi decreased significantly 30 minutes after aortic cross-clamping (7.37 +0.07) (p<0.0 1), 60 minutes after aortic cross-clamping (7.39 +0.08) (p<0.05), and 30 minutes after aortic unclamping (7.37 ±0.08) (p < 0.01), compared with pHi before aortic cross-clamping (7.50 ±0.06). Gastric mucosal pHi increased to the original level 60 minutes after aortic unclamping (7.46 ±0.08). Since a gastric mucosal pH above 7.35 is considered normal, these mean values of pHi were clinically insignificant. However, gastric mucosal pHi decreased below 7.32 in 5 patients during abdominal aortic surgery. Gastric mucosal pHi decreased further to 7.30 in 1 patient following aortic cross-clamping and below 7.30 in 3 patients 30 minutes after aortic unclamping. SCBF decreased significantly after aortic cross-clamping (28.1 ±4.8 mL/min/l 100 g) compared with the value before aortic cross-clamping (51.9 ± 11.3 mL/min/l 00 g) (p<0.01). Following aortic unclamping, SCBF returned to 41.7 ±7.4 mL/min/100 g.

It is concluded that transient episodes of significant intestinal mucosal ischemia may have been encountered occasionally in patients undergoing abdominal aortic surgery, but a sigmoid

Present available studies suggest that heparin prevents early vessel thrombosis in the immediate postoperative (POP) period after lower extremity bypass. Long-term anticoagulation with warfarin has also been used in these patients, based on its beneficial effect in preventing long-term graft failure. To compare the effectiveness between unfractionated heparin (UH) and low-molecular-weight heparin (enoxaparin) when used as transitional therapeutic POP anticoagulant therapy, a prospective study was performed. Seventy consecutive patients undergoing lower extremity bypass were studied. The initial 35 patients were started on a drip of UH 6 hours POP. The next 35 consecutive patients were treated with enoxaparin, the first dose starting 6 hours POP. All patients underwent subsequent anticoagulation with oral warfarin. There were no statistically significant differences between the two groups with regard to demographics, percentage of above/below the knee bypasses, type of conduit used, emergency operations, and overall complications. There was a significant difference in the length of stay (p = 0.05) in favor of the enoxaparin group, which also reflected a decreased overall cost in this group. In conclusion, POP anticoagulation with enoxaparin is as safe end effective as UH in patients undergoing lower extremity revascularization. Enoxaparin was associated with a decreased overall length of stay and hospital costs.

Ehlers-Danlos type IV is a major concern to vascular surgeons because it is often associated with spontaneous hemorrhage from arteries containing decreased type Ill collagen. Five members of a family with Ehlers-Danlos type IV and a review of another family of five with Ehlers-Danlos type IV are reported. Evaluation of the recent family included clinical evaluation as well as assay of collagen production. The age range of the three involved females and two males was 7 to 52 years. The father of the affected family had a spontaneous colon perforation at age 39. His son, at age 27, had a spontaneous rupture of the iliac artery. Revascularization was accomplished with difficulty. His daughter had a large cerebral bleed. Two granddaughters, ages 7, have not had any bleeding or aneurysmal events. The amount of type Ill collagen was only 10% of normal in the patient with the iliac artery rupture. The three females all exhibited similarly low levels of type Ill collagen. The father's type Ill collagen level was not sufficiently low to confirm Ehlers-Danlos type IV, although he had a spontaneous colon perforation. In the other Ehlers-Danlos type IV family of five, the three surviving members had type Ill collagen levels as low as 5% of normal. Two family members died after spontaneous iliac rupture at ages 24 and 33. Both families exhibited an autosomal dominant inheritance pattern. Ehlers-Danlos type IV remains a challenging problem for vascular surgeons. It is transmitted as an autosomal dominant inheritance with a high degree of penetrance. Spontaneous arterial and intestinal perforations should alert the clinician to the possibility of Ehlers-Danlos type IV. Patients should be evaluated noninvasively. Arterial repairs may not be successful in these patients because the vessels are extremely friable. Assays of collagen production are advisable in establishing the diagnosis.

Endograft repair has rapidly become an alternative to conventional open repair of abdominal aortic aneurysms. Various trials continue to show decreased morbidity when compared to open repair. However, as with any new procedure, complications specifically related to this technique are being described. Herein, we report a case of an isolated ischemic jejunal stricture presenting as a small-bowel obstruction secondary to cholesterol emboli following endograft repair of an abdominal aortic aneurysms.

The efficacy of balloon angioplasty with stent placement is compared to surgical patch angioplasty for thrombosed upper arm hemodialysis grafts with stenotic lesions at the venous anastomosis. Patients with thrombosed hemodialysis grafts terminating at the axillary vein were reviewed. Thirty-eight stents were placed after thrombectomy and venous balloon angioplasty in 26 patients. Fifteen case-matched controls underwent 23 polytetrafluoroethylene patch angioplasties for similar lesions. Kaplan-Meier survival analysis was used for statistical comparison. Primary patency for stent placement compared with patch angioplasty was not statistically different at any time through 1-year follow-up (37% vs 55% at 3 months, 25% vs 45% at 6 months, and 25% vs 15% at 12 months, respectively; p = 0.37). Secondary patency rates were slightly better for patch angioplasty compared with stent placement (78% vs 59% at 3 months, 78% vs 48% at 6 months, and 54% vs 32% at 12 months, respectively) however these differences were not statistically significant (p = 0.13). There was no difference in complication rates between groups. Sustained patency is poor for both angioplasty with stent placement and surgical patch angioplasty when revising thrombosed dialysis grafts with anastomotic axillary vein stenosis. These data suggest slightly better patency for the routine use of patch angioplasty for these lesions. However, the endovascular approach appears to be a reasonable alternative when surgical exposure is difficult.

As increasing experience and comfort with endovascular interventions performed in an outpatient setting has occurred, the safety and cost effectiveness of performing these procedures without an overnight stay were analyzed, especially when endovascular procedures were combined with open vascular operations requiring an arteriotomy and surgical closure. Ninety patients underwent endovascular procedures alone or concomitantly with open, minor vascular operations to salvage a failing graft between February 1994 and June 1999. Patients undergoing endovascular interventions during primary lower extremity bypass or other major surgical procedures were not included in this review because they were not candidates for outpatient procedures. Balloon angioplasty alone (79) or angioplasty with stent placement (1 1) was performed to treat stenoses in 50 failing grafts, 16 iliac, 14 femoral, 5 tibial, and 5 axilla/subclavian arteries. A significant increase in outpatient procedures was accomplished as more experience was garnered with these techniques: 19% (8/42) between 1994 and 1996 vs 57% (28/48) between 1997 and 1999 (p = 0.001). Age and comorbidity did not play a role in determining the need for admission because there were no significant differences in patients with diabetes mellitus, hypertension, smoking, or hyperlipidemia and those admitted or discharged the same day (p>0.05). Patients admitted for overnight observation tended to have longer mean operative times and more complex revascularizations than outpatients (1 10 vs 69 min, respectively; p<0.0001). Twenty-seven patients underwent surgical exposure of the access vessel: 63% (17) were admitted and 37% (10) were discharged the same day. Sixtythree patients underwent a percutaneous procedure: 42% (27) were admitted and 58% (37) were discharged the same day. Outpatients were more likely to receive only local anesthesia (83%; 30/35) compared to patients admitted overnight (67%; 36/53); the remaining patients received spinal or epidural anesthesia. Complications included graft thrombosis within 30 days in 6% (5/90) of patients and arterial graft infection in 2% (2). No patient required surgery for bleeding. The average charges for outpatient interventions were $1980 compared to $10,026 for patients who stayed overnight (p<0.0001). As vascular surgeons become more experienced and comfortable with outpatient endovascular procedures, especially when performed in combination with open minor vascular surgery, significant cost savings can be realized without sacrificing patient safety. Even when open surgical exposure is planned, patients should be instructed preoperatively to anticipate discharge the day of their procedure to minimize resistance to this strategy.

Arterial access for endovascular aortic aneurysm repair is usually gained through a common femoral artery approach. In small femoral arteries this can be difficult or even impossible owing to the large size of the introduction sheath of the delivery system. In such cases the iliac arteries or the abdominal aorta can be used for vascular access, although, in heavily calcified arteries, even this can be hazardous. The authors report an 81-year-old woman with a contained rupture of the thoracic aorta in whom a polyester graft was used to facilitate vascular access to the common iliac artery for a safe two-stage endovascular repair of the aneurysm.

Aneurysms of the pedal arteries are uncommon; however, they can be identified upon clinical exam and confirmed by angiogram and color-flow duplex scan. Surgical treatment options include ligation or primary repair. The authors present a case of an aneurysm of the dorsalis pedis artery in a diabetic patient. Primary repair of the aneurysm was accomplished using a venous autograft patch. The postoperative course was uneventful and the artery remains patent in follow-up.