HeRO Graft: Indications, Technique, Outcomes, and Secondary Intervention

Abstract

The Hemodialysis Reliable Outflow (HeRO) graft is a nontraditional, surgical, and endovascularly placed access that offers options in failing arteriovenous fistula/arteriovenous graft or catheter-dependent patients. The HeRO graft provides a unique option and is specifically referred to in the 2019 Kidney Disease Outcomes Quality Initiative (KDOQI) vascular access update. The interventional radiologist has a role and opportunity to work collaboratively with surgeons in assisting with (1) the identification, selection, preparation for, and placement of HeRO grafts and (2) providing post-placement maintenance to ensure long-term patency.

The Hemodialysis Reliable Outflow (HeRO) graft (Merit Medical, South Jordan, Utah) is a nontraditional, surgical, and endovascularly placed access that offers options in failing arteriovenous fistula/arteriovenous graft (AVF/AVG) or catheter-dependent end-stage kidney disease (ESKD) patients. The 2019 Kidney Disease Outcomes Quality Initiative (KDOQI) vascular access update provides guidelines for comprehensive evaluation of appropriate dialysis access needs and options for patients based on individualized ESKD life-plan. The HeRO graft provides a unique option and is specifically referred to in the document for this reason. The interventional radiologist (IR) has an important role to work collaboratively with surgeons in assisting with the preparation for and placement of this hemodialysis (HD) access, particularly in the setting of central venous occlusion (CVO) requiring recanalization and/or pre-HeRO tunneled HD catheter placement. Additionally, the IR can aid in providing long-term patency of the graft via post-placement maintenance ( Fig. 1 ).

Fig. 1.

HeRO Graft Overview. Hemodialysis Reliable Outflow (HeRO) graft schematic ( a ) and patient overlay ( b ). IR's role may include central venous occlusion recanalization followed by eventual outflow “nitinol” component placement. (Reprinted with permission. Katzman HE, McLafferty RB, Ross JR, Glickman MH, Peden EK, Lawson JH. Initial experience and outcome of a new hemodialysis access device for catheter-dependent patients. J Vasc Surg 2009;50(03):600–607, 607.e1). ⁴

Indications for HeRO Graft Placement

The 2019 KDOQI vascular access update provides a comprehensive evaluation of appropriate dialysis access needs and options for patients based on individualized ESKD life-plan. In general, HeRO graft candidates should have the following characteristics evaluated prior to placement: (1) all AV access options in the upper extremity have been exhausted; (2) patient has an appropriately high blood pressure; (3) patient has suitable anatomy for HeRO placement consisting of (a) adequate inflow artery and (b) patent or correctable central venous outflow; and (4) patient ESKD life-plan includes long duration on HD (i.e., > 1 year).

HeRO Graft Components

The HeRO graft components are briefly discussed. For IRs assisting surgical placement, familiarity with the “nitinol” venous outflow component and accessory component kit ( Fig. 2 ) is required. Additional information can also be found at the manufacturer's Web site.

Fig. 2.

Accessory components. Standard accessory components used in the outflow component placement. In the authors' experience, additional items are necessary for patients with prior recanalized central venous occlusion or complex tunneled hemodialysis catheter placement.

Manufacturer Description of Components

Arterial Graft Component

The HeRO graft arterial component has a 6-mm inner diameter (ID), 7.4-mm outer diameter (OD), and is 53 cm long, inclusive of the connector. It consists of an expanded polytetrafluoroethylene (ePTFE) HD graft with PTFE beading to provide kink resistance near the proprietary titanium connector.

Super HeRO Adapter and Support Seal System

The Super HeRO adapter and support seal system was developed to allow use of the venous outflow component with other standard wall and early cannulation vascular graft options beyond the standard HeRO arterial graft component.

Titanium Connector

The titanium connector attaches the arterial graft component to the venous outflow component and has a 6- to 5-mm (ID) transition. When using the Super HeRO system, additional adapters and support seals may be needed depending on the arterial graft used.

Venous Outflow (“Nitinol”) Component

The venous outflow component is composed of a radiopaque silicone tube with braided nitinol reinforcement, a 5-mm ID, 19 Fr (6.3 mm) OD, and is 40 cm long. It consists of radiopaque silicone with braided nitinol reinforcement (for kink and crush resistance) and a radiopaque marker band at the distal tip. The authors will refer to this portion of the HeRO graft as the “nitinol” component.

Accessory Component Kit

The accessory component kit ( Fig. 2 ) provided for HeRO graft placement includes a 10-Fr delivery stylet, 20-Fr peel away sheath (short and long), Y-adapter with one-way stopcock, hemostatic plug, vascular clamp, and 12-Fr and 16-Fr dilators. In our experience, for patients in whom central recanalization and/or trans-stent access was required for tunneled HD catheter placement, additional items beyond those included in the accessory component kit are required for venous outflow component placement.

Role of Interventional Radiologist in (HeRO) Graft Placement

In our institution, IRs work closely with transplant surgeons when HeRO graft placement is being considered. A multidisciplinary conference involving transplant surgery, interventional radiology, and interventional nephrology is held every 2 weeks, and patients considered for HeRO graft implantation are discussed. Additional items discussed in this conference include patient-specific items related to AVF/AVG creation site, dialysis access maintenance, or renal transplant candidacy evaluation and periprocedural interventions. In general, HeRO graft patients are not candidates for peritoneal dialysis and have exhausted traditional upper extremity AVF and AVG options.

The IR's role in the placement of the HeRO graft is to (1) place a tunneled HD catheter in the IR suite prior to HeRO graft implantation and (2) place the venous outflow component in the operating room (OR) on the day of HeRO graft implantation. Additionally, due to regular referrals for tunneled HD catheter maintenance, we help identify patients for potential HeRO placement and work with our surgical colleagues providing better access options to those who were deemed to be groin catheter dependent.

With the advent of technology and new techniques, IRs are able to manage CVOs for subclavian or IJ tunneled HD catheter placement, which facilitates HeRO graft placement in a population that would otherwise remain catheter dependent. Many patients planned for HeRO graft insertion require central venous recanalization with catheter placement as the initial step. For this reason, a staged approach for HeRO graft placement (i.e. IR suite for tunneled HD catheter placement, followed by OR suite for HeRO graft insertion) is typically used. HD catheter placement (with or without central venous recanalization) in the IR suite is usually planned within 1 week prior to HeRO graft placement. Studies support this staged approach if needed, as it did not result in increased infection rate. ¹ The details of the two stages are as follows.

Tunneled Catheter Placement in the IR Suite

Unique to catheter placement prior to HeRO graft insertion is that the goal is to create a safe intrathoracic tract (vascular or extravascular) through which a tunneled catheter is placed with its tip ending in the mid right atrium. The goal is not to establish flow through the occlusive venous system which makes this procedure slightly easier compared with central venous recanalization for the purpose of establishing flow. In the IR suite, tunneled catheter placement prior to HeRO graft placement occurs following CVO management (if needed) using recanalization techniques described in a separate article of this issue. ² If CVO recanalization fails or is not feasible due to long segment occlusion, one can advance a wire catheter combination from femoral access into the (preferably right) brachiocephalic/subclavian level. Even if the wire is not intraluminal, a balloon can be advanced over the wire and used as a target to puncture with a 21-gauge needle ( Fig. 3 ). Once the needle tip is in the balloon lumen, a 0.018-in wire can be pushed inside the balloon and kept in the balloon lumen while the balloon is slowly retracted from the femoral access (e.g., advancing the 0.018-in wire to the inferior vena cava (IVC) and femoral access). This establishes a through and through access which allows the IR to place a tunneled catheter after conversion to a 0.035-in system. Other options are to target a preexisting stent if present under fluoroscopy ( Fig. 4 ) or target a calcified fibrin sheath ( Fig. 5 ) in the occluded subclavian or brachiocephalic veins to facilitate tunneled catheter placement. Care is taken to ensure a smooth tunnel curve toward the glenohumeral joint to reduce the risk of nitinol component retraction. The aforementioned options are in addition to techniques used for central venous recanalization due to unique nature of HeRO placement which requires access to right atrium but not necessarily establishment of flow.

Fig. 3.

Central venous occlusion recanalization and balloon-target assisted hemodialysis catheter placement. Right upper extremity (RUE) venogram demonstrating central subclavian and brachiocephalic occlusion; partial filling defects in the brachiocephalic vein (black arrow) provide a target ( a ). Superior vena cava (SVC) venogram demonstrates close proximity to the recanalized tract ( b ). RF wire recanalization was required from the SVC with snaring (black arrow) of the wire from the RUE access providing “flossing” access ( c ). After confirmation and serial venoplasty of the recanalized tract, an inflated balloon in the central subclavian vein was targeted and punctured (black arrow) with a 21-gauge needle ( d ) which facilitated catheter ( e ) and outflow component ( f ) placement.

Fig. 4.

Trans-stent hemodialysis catheter placement. Right upper extremity venogram demonstrating chronic occlusion of a prior axillosubclavian and brachiocephalic stent construct ( a ). Central subclavian aspect of the stent construct was targeted with a 21-gauge needle and facilitated wire access to the inferior vena cava ( b ). Serial venoplasty of the tract facilitated catheter placement ( c ).

Fig. 5.

Fibrin sheath target hemodialysis catheter placement. This patient had unsuccessful recanalization attempts from both upper extremities using standard and advanced techniques. Right upper extremity (RUE) venogram demonstrated long-segment chronic occlusion from the axillary vein centrally ( a ). Magnified chest radiograph demonstrates a partially calcified fibrin sheath (black arrowheads) from a previously placed central venous catheter ( b ). Direct needle puncture of the calcified fibrin sheath and RF wire (black arrow) advancement to an SVC target snare (white arrow) was performed ( c ) with eventual snaring of the RF wire and “flossing” access obtained ( d ). Coronal cone-beam CT confirming safe tract not violating pulmonary structures ( e ). Final catheter placement ( f ) prior to HeRO outflow component insertion.

HeRO Graft Insertion in the Operating Room Suite

In the operative suite, a mobile fluoroscopic unit is needed for nitinol component placement. A stiff 0.035-in wire is advanced through the previously placed tunneled HD catheter into the IVC. A second wire, which could be another stiff 0.035-in glide wire or superstiff 0.035-in Amplatz wire can be placed through the second lumen of the catheter for safety access. Evaluation of the preexisting tunnel is made to ensure a smooth curve toward the glenohumeral joint, and if not, a new tunnel is created toward the catheter exit site. It is important for patency of the HERO to choose the least mobile tract to minimize retraction of the catheter during placement. If the provided accessory kit is used, the catheter is removed, tract is serially dilated, peel-away sheath is inserted, and nitinol component (preloaded with the delivery stylet) is advanced until the tip location is in the mid-right atrium. In our experience, preloading the nitinol component with a 7- or 8-mm balloon and using the tip of the balloon as a dilator make advancement of the nitinol component easier. If recoil of the CVO tract occurs following catheter removal, balloon dilation of the tract with 7-, 8-, and sometimes up to 10-mm balloons will also help advance the nitinol component to the right atrium ( Fig. 6 ). After placement, wires and catheters are removed and the vascular clamp placed on the external portion of the nitinol component at the glenohumeral joint until surgical anastomosis is performed. The IR positions the tip of the HeRO outflow component at the mid right atrium under fluoroscopy and a final confirmation radiograph obtained by the surgical team to ensure proper placement at the end of surgical components of the procedure. Postprocedure chest radiographs with neutral arm position (adduction) are also obtained to ensure appropriate tip location prior to discharge.

Fig. 6.

Operating room (OR) placement of outflow (“nitinol”) component. C-arm images obtained during OR outflow component placement. Stiff wire access is placed into the previously placed hemodialysis catheter (black arrow) and into the inferior vena cava ( a ). The catheter is removed, and a 7-mm balloon preloaded through the outflow component is advanced over the wire. Note that the balloon is intentionally positioned partially outside the outflow component to allow venoplasty of any recoil of the central venous occlusion and help in stepwise advancement of the outflow component ( b ). The radiopaque tip of the nitinol component (black arrow) is confirmed in the mid-right atrium ( c ). Postprocedure chest radiograph confirms no inadvertent advancement or retraction of the outflow component tip (black arrow) during graft anastomosis ( d ).

HeRO Graft Outcomes

Multiple studies have evaluated the HeRO graft with favorable results compared with long-term tunneled HD catheter placement ^{3 4 5} and comparable complications and maintenance interventions to standard upper extremity HD grafts. ^{5 6 7 8 9 10 11} Compared with tunneled HD catheters, HeRO grafts showed 69% lower infection rates, 16 to 32% improved dialysis clearance, and 50% reduced maintenance interventions. Patency rates of the HeRO graft were also comparable to AVGs. ^{4 7 12 13}

Secondary Interventions and Complications

Secondary interventions required for HeRO grafts due to pseudoaneurysm, stenosis, or thrombosis are predominantly similar to those encountered with other malfunctioning vascular HD access ( Fig. 7 ). Complications of HeRO graft placement are mostly related to the recanalization procedures that are required for tunneled HD catheter placement. Rare complications that might be encountered include outflow component migration requiring surgical correction ( Fig. 8 ) or endovascular retrieval ( Fig. 9 ), which has been previously reported. ¹⁴ It is important to note that complete disruption and migration of the outflow component occurs when the provided titanium connector is not used or not utilized appropriately.

Fig. 7.

HeRO graft thrombectomy. Conventional appearance of a post-thrombectomy HeRO graft. Note the antegrade (black arrow) and retrograde (white arrow) directed access sheaths and brachial artery positioned catheter (black arrowhead) demonstrating patent flow through graft ( a ) and nitinol component ( b ). Chest radiograph showing the configuration of a “necklace” HeRO graft (black arrow—anticipated location of the axillary artery) ( c ). Thrombectomy procedure of a “necklace” graft, with inflow provided via the left axillary artery (black arrow) ( d ).

Fig. 8.

Outflow component migration. Immediate post-HeRO graft placement chest radiograph demonstrating inadvertent advancement of the nitinol component to the hepatic inferior vena cava (arrow) ( a ). The patient returned to the operating room for retraction and re-anastomosis to correctly reposition tip location to the mid-right atrium (arrow) ( b ). A patient with retraction of the nitinol component (arrow), likely due to excessive chest wall soft tissues ( c ). This required surgical correction.

Fig. 9.

Outflow component retrieval and HeRO graft salvage. Chest radiograph demonstrates migration of the outflow component to the inferior vena cava (IVC) (arrow) ( a ). Scout image from endovascular retrieval demonstrating stable outflow component position in the IVC (arrow) ( b ). Right upper extremity fistulogram demonstrating patent flow through the graft and prior outflow component tract ( c ). Right femoral access was obtained and the outflow component snared (black arrow) and removed through a 22-Fr access sheath ( d ). The outflow component tract was serially venoplastied and overlapping self-expandable covered stents placed to act as an “outflow component,” with post-deployment fistulogram demonstrating patent outflow ( e ). Chest radiograph 4 years post intervention ( f ). This modified HeRO graft has been successfully used for 4 years with intermittent interventions similar to conventional HeRO graft interventions. (Case courtesy of Dr. Ulku C. Turba).

Conclusion

The HeRO graft is a unique viable long-term vascular HD access solution in patients without other upper extremity AV access options. Interventional radiology has pioneered many techniques for CVO management, which are directly applicable to the placement of the outflow “nitinol” component of the HeRO graft. As such, interventional radiology has a unique role to work collaboratively with surgeons in improving placement and maintenance of this unique HD access option.