[Multislice computed tomographic angiography in the assessment of central veins for endovascular treatment planning: comparison with phlebography]. / Angio-TC MS nello studio dei vasi venosi centrali per la pianificazione del trattamento endovascolare: studio comparativo con la flebografia.

The dysfunction of a vascular access for hemodialysis and its loss may depend on drainage difficulties of the superficial or deep venation due to hemodynamically significant stenosis or obstruction of a central vein, which generally involve the innominate-subclavian veins or superior vena cava. These alterations are often neglected due to their central and deep location; when there is hemodynamic compensation, they may remain asymptomatic. For these reasons every suspect clinical sign for central vein stenosis (gross arm syndrome or venous hypertension in an arteriovenous fistula) must not be ignored, as timely intervention is essential for functional recovery of the vessel and for the protection of the arteriovenous fistula. The modern imaging techniques ensure thorough diagnostic assessment, while the possibilities of endovascular treatment with interventional radiology allow, in a large proportion of cases, optimal minimally invasive treatment, but above all the recovery of venation in a hemodialyzed patient. We report our experience with multislice computed tomographic angiography (MS-CTA) and reconstruction software for treatment planning of central vein stenosis or obstruction. Forty-nine patients were studied with MS-CTA (GE 16). Images were acquired in the venous phase (120-180 seconds after contrast medium injection) followed by digital vascular reconstruction (AutoBone for bone removal, vessel analysis for caliber and length measurements, thin and curved MIP, MPR). Within a week control phlebography was performed. The venous tree was divided into seven segments and analyzed in a double-blind fashion with a distinction between patent segments, 50-70% stenosis, >70% stenosis, occlusion, and collateral vascular beds. There was excellent correspondence in all the examined segments for patency, >70% stenosis, and occlusion, with high sensitivity (98%), specificity (99.3%), and diagnostic accuracy (99.1%). The binomial test demonstrated a highly significant concordance (alpha=0.99) for all patients and in all vascular segments with the exception of 70% stenoses, in which MS-CTA gave a slight overestimate. In the central venous district, color Doppler ultrasonography may not be as effective as for the peripheral study of arteriovenous fistulae, and second-level imaging techniques such as MS-CTA are more useful. We suggest that endovascular treatment must be preceded by MS-CTA. This examination shows the lesions that may benefit from endovascular treatment and recognizes ''uncrossable'' lesions, ie, the ones that will not benefit from treatment. Moreover, it allows accurate planning of endovascular treatment by showing the lesion type (stenosis or obstruction), the position and extension of the involved vessels, the vessel caliber above and below the lesion, and the possible presence of a collateral vascular bed. MS-CTA with dedicated reconstruction software, if correctly performed and accurately reconstructed, is a precious tool for diagnosis and treatment planning.

Drug-eluting balloon for the treatment of failing hemodialytic radiocephalic arteriovenous fistulas: our experience in the treatment of juxta-anastomotic stenoses.

PURPOSE: The purpose of this article is to report our experience with drug-eluting balloons for the treatment of juxta-anastomotic stenoses of failing radiocephalic hemodialytic arteriovenous shunt and to evaluate the primary and secondary patency (PP and SP). METHODS: After approval by the local hospital's Ethical and Scientific Review Board, 26 consecutive patients with juxta-anastomotic stenosis of radiocephalic hemodialytic shunt were treated with angioplasty with drug-eluting balloon. The main objective was to evaluate PP defined, in accordance with the Kidney Disease Outcomes Quality Initiative recommendation, as the absence of dysfunction of the vascular access, patent lesion or residual stenosis <30% and no need for further reintervention of the target lesion (TL). PP and SP at 6, 12 and 24 months were evaluated, with echo color doppler and phlebography, for both arteriovenous fistulae, defined as absolute, and TL. RESULTS: Immediate postprocedural technical and clinical success was 100% for all the patients; we had only one technical failure in repeated treatments. At 6 months the absolute and TL PP was 96.1%; at 12 months the absolute PP was 81.8%, TL PP 90.9%, absolute SP 95.4%, TL SP 100%; at 24 months the absolute and TL PP was 57.8%; absolute and TL SP 94.7%; only one arteriovenous fistula was lost during the period. CONCLUSIONS: The use of drug-eluting balloons, after standard angioplasty, improves primary patency and decreases reinterventions of TL in juxta-anastomotic stenoses of failing native dialytic arteriovenous shunts.

Venae comitantes as a potential vascular resource to create native arteriovenous fistulae.

PURPOSE: The arteriovenous fistula (AVF) represents the gold standard for hemodialysis (HD) vascular access. In some critical cases, use of the deep venous circle may represent an alternative approach and venae comitantes could be employed for this purpose. METHODS: Sixty patients with chronic renal failure in which the deep venous circle was used to create an AVF were identified; of the 48 who had a direct anastomosis between the brachial artery and vena comitans, 42 had a long-term follow-up (mean follow-up 59 weeks), while six were lost to follow-up. RESULTS: Immediate success (patency and palpable thrill) was achieved in 88% of cases (primary and early failure 12%). Primary accessibility rate was 62%, while 11 patients required a second surgical approach to make the vein accessible to needling. Secondary accessibility rate of 71% was due to surgical revisions. In the 80-week observation period, the complication rate was 10% with irreversible loss of the AVF in all these cases. Cumulative patency was 71% at the 80th week. Including all 42 patients, technical and functional success rate, defined as vein accessibility to needling and chance of an adequate HD treatment, was 62%. CONCLUSIONS: AVF employing venae comitantes may represent a suitable alternative in the absence of other vascular accesses for HD.

Atypical placement of hemodialysis catheters in patients with complete and irreversible obstruction of central venous vessels.

PURPOSE: This article describes the approach to atypical placement of central venous catheters (CVC) in dialysis patients with complete untreatable obstruction of central venous vessels. METHODS: Five patients with complete obstruction of central venous vessels underwent CT venography and digital venous angiography. After ultrasound-guided and radioscopic-assisted cannulation of the internal jugular vein, permanent CVCs were placed in atypical locations: in two patients a preliminary venous angioplasty was performed to facilitate the catheter positioning in a mediastinal enlarged collateral vein and in a persistent left superior vena cava; in three patients the CVC was placed in the azygos vein, enlarged because of the obstruction of the superior vena cava. RESULTS: In all cases, we achieved satisfactory morphological and functional immediate results. Hemodialysis (HD) was carried out long term in all patients except one who presented a non-functioning CVC after 4 months. In one case the catheter, still functioning well after 9 months, was removed due to kidney transplantation. The CVC in the left superior vena cava was replaced with a longer one after 12 months, and it is still functioning well 3 months after replacement. The patency of the other two catheters has to date been kept for 9 and 18 months. CONCLUSIONS: The placement of CVC for HD in atypical sites can be considered a viable option in extreme cases; adequate imaging support is paramount in order to facilitate the procedure and to avoid complications.