Jacopo Scrivano

Preventive hemostasis for hemodialysis vascular access surgical reinterventions

Surgical reinterventions for treatment of complications or ligation of haemodialysis vascular access (VA), when performed in or below the mid/lower part of the upper arm, could benefit from the use of preventive haemostasis with an inflatable tourniquet. This technique offers several advantages, such as the reduced risk of bleeding and the increased accuracy of dissection allowing for a minimally invasive approach. The use of preventive haemostasis is safe, economical and time-saving. All the secondary procedures on VA that could benefit from its use are reviewed.

Preoperative duplex examination in patients with dialysis access-related hand ischemia: indication for distal radial artery ligation

Purpose To demonstrate that treatment with distal radial artery ligation (DRAL), based on preoperative evaluation with duplex ultrasound, is effective for correction of hand ischemia related to distal radiocephalic arteriovenous fistula (AVF). Methods Two patients with symptoms of hemodialysis access-induced distal ischemia (HAIDI) related to radiocephalic AVF at wrist (necrotic lesion of fingers, pain at rest and loss of sensory function) were studied with preoperative duplex examination. Color Doppler ultrasound (CDU) showed low-normal flux (700 and 500 mL/min respectively), retrograde flow in the DRA and increased digital perfusion after manual occlusion of DRA. They were both treated by ligation of the DRA. Results Both patients had immediate improvement of ischemic symptoms. Reversed DRA flow disappeared and peripheral flow ameliorated. Postoperative AVF flow was 500 and 350 mL/min, stable at 16 and 8 months of follow-up, respectively. Conclusions Preoperative CDU examination, simulating reversed DRA flow interruption, seems to be an effective tool to predict the success of DRAL procedure.

Echographic landmark of cephalic and collateral accessory vein at forearm in preoperative evaluation for hemodialysis angioaccess

Introduction Superficial veins in the upper arm differ according to their relationship to the superficial fascia. We investigated the echographic landmark of the cephalic vein (CV) to correctly distinguish it from the collateral accessory vein (CAV) before hemodialysis angioaccess creation. Materials and Method Twenty consecutive patients were evaluated by ultrasonographic scan. The echographic features of CV and CAV together with their relationship were described. Results Ninety-five percent of patients presented both CV and CAV (75% CAV laterally located, 25% medially located). CV and CAV diameters were 2.9 (±0.65) and 2.0 (±0.70), respectively. Conclusions CV differs from CAV for its anatomic location at forearm. Such a difference is clearly evident under ultrasound examination, despite any recommendation in ultrasound guidelines. Whether the exclusive use of CV for angioaccess creation can lead to a better outcome will be ascertained by further studies.

Impaired Maturation of Arteriovenous Fistula for Haemodialysis Due to Forearm Artery Stenosis: Percutaneous Endovascular Treatment:

Introduction Distal autogenous arteriovenous fistula (dAVF), considered the “gold standard” vascular access for haemodialysis, suffers from a high rate of impaired maturation. One of the usual causes is low-flow associated forearm arterial stenosis. In such cases, endovascular treatment by percutaneous transluminal angioplasty represents a helpful option to enable maturation of the vascular access. Currently, there are few reports concerning the treatment of this complication. Therefore, we describe our single-centre experience based on a retrospective review of prospectively collected data. Patients and methods We treated 18 consecutive patients from July 2007 to January 2014 (16 radio-cephalic, 2 ulno-basilic distal AVF). A low flow due to forearm artery stenosis was diagnosed by duplex examination, as routinely performed one month after dAVF creation. An anterograde trans-brachial access was used for a 4-mm high-pressure angioplasty of the stenosed artery. Results All interventions resulted in patent fistulas. Isolated percutaneous transluminal angioplasty (PTA) was required without need of stent placement. Mean blood flow increased from 304 mL/min, preoperatively, to 671 mL/min (p<0.01), as checked one week after the procedure. One-year primary and secondary patency were 84% ±7.3% and 92% ± 9.2%, respectively. Under no circumstances did access-induced distal ischemia occurred during follow-up. Conclusions Endovascular approach is a helpful and minimally invasive procedure for treatment of delayed maturation of dAVF related to forearm artery stenosis.

TRP Channels: Emerging Links Between Ca2+, Kidney and Hypertension

Cationic channels with variable selectivity for Ca2+, K+, and Na+ are ubiquitous in non-excitable tissues as well as contractile cardiac cells and vascular smooth muscle (VSMC). They are involved in multiple cell functions, including contraction and proliferation of VSMC, key to the regulation of vascular tone and blood pressure. A large superfamily includes at least 28 highly conserved heterotetramer homologues of Drosophila TRP (transient receptor potential) channels. Direct evidence exists for TRPC, TRPV, TRPP gating ion entry in vascular cells, as well as in epithelial cells of kidney and intestine, thus controlling homeostasis and external balance of divalent cations. Mice deficient in TRPV5 display phenotypic defects resembling human idiopathic hypercalciuria and impaired bone mineral density. Polycystin 2, encoded by the PKD2 gene, is an epithelial transmembrane TRPP2 protein, whose mutation is associated with autosomal dominant polycystic kidney disease (ADPKD). TRP ion channels may therefore play a role in the pathogenesis of systemic arterial hypertension, pulmonary hypertension, as well as hypertension complicating renal disease via effects on vascular tone and/or on the electrolyte composition of body fluids.