The role of vascular radiology in hemodialysis access

Use of intraoperative venography to guide the distal portion of a ventriculoatrial shunt past an obstruction in the central veins: technical case report

OBJECTIVE

Ventriculoatrial (VA) shunting is commonly used to treat hydrocephalus when ventriculoperitoneal shunting has failed. Placement of a VA shunt in patients with narrowing or occlusion of the central veins presents considerable difficulty because few imaging modalities exist to safely and reliably insert a guidewire or atrial catheter past the occlusion. We report the use of intraoperative venography to guide the placement of the distal portion of a VA shunt in a patient with a valve blocking the left brachiocephalic vein.

CLINICAL PRESENTATION

A 42-year-old man with pseudotumor cerebri and a left ventriculoperitoneal shunt presented with severe headaches. He was diagnosed with partial distal shunt obstruction. Because of a history of failed attempts at ventriculoperitoneal shunting, conversion to a VA shunt via the left internal jugular vein was planned.

TECHNIQUE

Surgery was performed by using the standard technique until resistance was encountered when inserting a guidewire into the internal jugular vein. Intraoperative venography of the central veins was performed, which showed a large valve blocking progression of the guidewire in the left brachiocephalic vein. Using fluoroscopic guidance, a 0.035-inch guidewire was successfully directed through the vein past the obstruction and exchanged for a peel-away introducer. The distal shunt catheter was then inserted, and the correct position in the atrium was confirmed fluoroscopically.

CONCLUSION

When obstruction of the central veins is found during a VA shunting procedure, intraoperative venography is a useful method to aid in the placement of the atrial catheter through the central veins.

The Value of Preoperative Vascular Imaging in the Selection and Success of Hemodialysis Access

The purpose of this study was to determine the value of preoperative vascular imaging (PVI) in the selection of an arteriovenous fistula (AVF) for hemodialysis with respect to site selection, maturation, patency, and functionality. We retrospectively evaluated 482 AVFs and arteriovenous grafts (AVGs) created in 321 patients who were regularly undergoing hemodialysis at our university's hemodialysis centers. The patients were divided into two groups according to PVI status. The patients in group 1 (n = 260) underwent Doppler ultrasonographic evaluation and venographic studies as well as physical examination before operation. The patients in group 2 (n = 222) underwent only physical examination before operation. Both groups were compared with respect to vascular access type, access maturation rate, and duration of access patency. In group 1, central veins were also evaluated for possible stenosis, and significant asymptomatic stenosis was treated with interventional techniques. The patients in group 1 were significantly older than those in group 2 and had a significantly higher mean number of previous central venous catheterizations and vascular access sites. At the initiation of the study, 234 of the vascular access sites had matured with a success rate of 90% in group 1. In group 2, however, 152 (68.5%) of the vascular access sites had matured. AVGs of the vascular access type were created in 31.5% of patients in group 1 and in 12.6% of patients in group 2. The mean duration of primary patency in group 1 overall (i.e., AVFs and AVGs) was 14.7 +/- 16.8 months, and the 6-month and 12-month patency rates were 72% and 46%, respectively. The mean duration of primary patency in group 2 overall was 11.9 +/- 9.4 months, and the 6-month and 12-month patency rates were 71% and 41%, respectively. Patients in group 1 had a significantly longer mean primary patency time than did those in group 2 (P = 0.024). Sixty-six cases of central vein stenosis were detected during PVI studies and treated interventionally. After those interventions, 38 AVFs and 28 AVGs were created, and all matured sufficiently without exception. As an adjunct to physical examination, PVI evaluations (venography, Doppler ultrasonography) can be used to determine the likelihood of the maturation of vascular access sites and can reveal problems such as central vein stenosis, which can then be treated promptly with percutaneous intervention. In patients with end-stage renal disease, these interventions should lead to a decrease in morbidity and mortality and improved quality of life.

Effect of Secondary Interventions on Patency of Vascular Access Sites for Hemodialysis

PURPOSE

To determine the impact of secondary procedures performed to maintain arteriovenous fistula (AVF) and arteriovenous graft (AVG) patency.

METHODS

There hundred and eighty six vascular access procedures were retrospectively evaluated. 156 (40.4%) patients required radiological interventions to treat acute thrombosis, swelling of the extremity with the access site, insufficient hemodialysis, or stenosis at an anastomotic site.

RESULTS

The 386 cases comprised 106 AVGs and 280 AVFs. In 138 of the 156 cases, which required a radiological intervention, the treatment was successful and saved the vascular access site. The unassisted post-intervention patency time for these 138 successful cases was 13.1 +/- 12 months (range, 1-65 months). Twenty-nine (63%) of the 46 access sites treated with surgical thrombectomy were saved.

CONCLUSIONS

Frequent, regular follow-up of hemodialysis patients with vascular access sites is the best way to diagnose problems early and allow the best chance of long-term function.