Abstract
Central venous obstructions that impedes catheter placement or results in catheter dysfunction is a significant problem for haemodialysis patients. Recanalization can be performed with an intent to restore central venous access, improve outflow from arteriovenous fistula or to relieve symptomatic venous obstructions. Sharp recanalization encompasses various interventional techniques using a sharp instrument to puncture through or bypass around a venous obstruction. In this paper we outline our experience performing CT guided sharp recanalization and review alternative sharp recanalization techniques that are specifically used to restore haemodialysis access in patients with thoracic central venous obstruction.
Keywords
Introduction
Up to 41% of patients on haemodialysis have a significant central venous obstruction (CVO). 1 CVO are commonly caused by prolonged use of central venous catheters (CVC) which can incite intimal hyperplasia, fibrosis and calcification resulting in stenosis or occlusion. 1 CVO can also develop in haemodialysis patients who are catheter naïve due to turbulent flow related to arteriovenous fistula. 2 CVO that impedes catheter placement or results in catheter dysfunction is a significant problem for haemodialysis patients.
Thoracic central venous obstruction (TCVO) can be classified anatomically into four subtypes as outlined by the SIR reporting guidelines. 3 Type 1 is defined as a unilateral obstruction of the internal jugular vein (IJV) or subclavian vein (SCV). Type 2 is a unilateral obstruction of the brachiocephalic vein (BCV) or a combined obstruction of the IJV and SCV. Type 3 is a bilateral obstruction of the BCVs and Type 4 is an obstruction of the superior vena cava (SVC).
In this cohort of patients recanalization can be performed with an intent to restore CVC access, to improve outflow from arteriovenous fistula or to relieve a symptomatic venous obstruction. Sharp recanalization is an advanced technique, reserved for obstructions that cannot be crossed and plastied using conventional glide wires. It encompasses various interventional techniques using sharp instruments to puncture through or bypass around a venous occlusion.
In this paper we outline our single centre experience performing CT guided sharp recanalization and review alternative sharp recanalization methods to restore central venous access.
Material and methods
A retrospective review of the PACS system identified 600 radiologically inserted central venous dialysis catheters between 2020 and 2023. Six of these were inserted using CT guided sharp recanalization. All six patients were on haemodialysis and had TCVO related to prior use of central venous catheters. A CT venogram was performed for preprocedural planning in all patients.
Informed consent was obtained. Midazolam and fentanyl were used for conscious sedation. The procedure was performed in two consecutive stages. The first stage used conventional CT guidance and the second stage used fluoroscopic guidance in the angiography suite. The procedures were performed by the same interventional radiologist with greater than 15 years of experience.
A 20-22G Chiba needle (Cook Medical; Indiana) was advanced in a centripetal direction from the right supraclavicular region beneath the clavicle (Figure 1). Intermittent CT guidance with three slice acquisitions (Siemens Somatom; Germany) was used to track the needle tip as it was advanced incrementally. Care was taken to ensure the needle tip was always centred in the middle of the scan range. The needle traversed the occluded central vein until patent vein beyond the obstruction is reached (Figures 2 and 3). Under CT guidance a microwire was advanced into the patent SVC, through the right atrium into the IVC. The needle was exchanged for a triaxial Neff set (Cook Medical) over the wire to secure access across the TCVO.
Graphic outlining the trajectory of a Chiba needle through the occluded right IJV and BCV into the patent SVC.
(a) Preprocedural venogram demonstrates occlusion of the left brachiocephalic vein in a patient with a Type 3 TCVO, (b) intraprocedural CT acquisition; Needle tip traversing the occluded right BCV (arrow), (c) intraprocedural CT acquisition: The advanced needle tip now positioned in the patent SVC (arrow) and (d) chest X-ray demonstrating subsequent placement of a HeRO graft through the recanalized tract, with the tip located superiorly in the right atrium (arrow).
(a) Preprocedural noncontrast CT in patient with a Type 4 TCVO. Chronic calcific occlusion of the SVC (arrow). (b) Intraprocedural CT acquisition: Needle tip (arrow) positioned within the distal SVC at the cavoatrial junction, immediately anterior to the dense calcification. The needle transverses the occluded SVC. (c) Coronal MIP shows the triaxial sheath across the stenosis. Note the dense pericardial calcification. (d) Spot fluoroscopic image shows placement of a tunnelled Hickmann line for later conversion to HeRO graft.
At this point the sheath was capped and secured to skin. The patient was immediately transferred to the angiographic suite for the second stage. Under fluoroscopy a 0.035″ super stiff Amplatz wire (Boston Scientific; Massachusetts) was placed via a triaxial 4 Fr sheath. The wire was advanced into the IVC. The tract was dilated over the working wire and a central line was placed via a peel away sheath.
Results
All six procedures were technically successful. One patient experienced moderate transient pain on tract dilation. No complications occurred. Average central venous occlusion recanalized was 5.6 cm (measured from the superior border of the clavicle to the level of patent BCV or SVC). In three patients a 14.5 Fr tunnelled dialysis catheter was placed, one of which was converted to a Haemodialysis Reliable Outflow graft (HeRO; Merit Medical; Utah) 2 months later. The remaining three patients had various temporary central venous lines placed, all of which were converted to HeRO graft (Table 1). At median followup of 17.5 months, five of the six patients had functioning central venous catheter or HeRO graft. One patient had the CVC removed at 7 months due to infection.
Procedure details and outcomes.
Measured from the superior border of the clavicle to patent BCV or SVC.
Literature search strategy
To generate an inclusive list of articles related to the topic in the PubMed online database, the following search terms were used: ‘sharp recanalization’ OR ‘sharp recanalization’ OR ‘central vein recanalization’ OR ‘central vein recanalization’ AND ‘venous obstruction’ OR ‘venous occlusion’ OR ‘venous stenosis’ AND ‘dialysis access’ OR ‘dialysis catheter’ OR ‘venous catheter’ OR ‘central venous line’ OR ‘dialysis line’. This yielded 131 results which were screened manually to identify 11 series outlining sharp recanalization techniques for restoring central venous access (Table 2).
Studies describing sharp recanalization techniques to re-establish central venous access.
Discussion
Restoring vascular access in the setting of TCVO can be extremely challenging and there remains no consensus on the optimal method. The choice of technique depends on factors including the location and length of stenosis, the purpose of the procedure, patient factors and resources available to a department. The CT guided technique used in our institution was first described in 2016 by Khalifa et al., who reported its success in three cases. 4 While many techniques under the banner of sharp recanalization focus on recanalization with stenting to improving venous return, this review explores techniques specifically used to restore vascular access in patients with TCVO.
Arabi et al. presented an approach to restoring central venous access using a BRK-1 Transseptal needle (St Jude Medical, MN, USA), a device originally designed for transseptal cardiac catheterization. 5 In their study of seven patients, the transseptal needle was inserted via femoral access and the TCVO was punctured in a centripetal direction towards a snare placed beyond the occlusion in the patent brachiocephalic vein. The centripetal puncture direction was preferred as the needle is orientated away from the heart and against blood flow. Upon successfully entering patent vein, through-and-through access was established and the occluded segment was recanalized by venoplasty using high pressure balloons. Five of the seven patients had dialysis catheters placed and the other two patients underwent stenting of the occluded segment. All seven procedures were technically successful, however two patients developed major complications, which included a haemothorax and a hemopericardium.
Transvenous sharp recanalization using a sheathed TIPS needle or the sharp end of a stiff hydrophilic wire was reported in six patients with occluded brachiocephalic veins. 6 The sharp instrument was used to puncture through the stenosis under orthogonal fluoroscopic guidance towards an intraluminal target beyond the occluded segment placed via femoral access. All six cases were technically successful, however one case was complicated by central vein perforation, which was managed with covered stent placement. Yang et al. also reported a series of 16 patients treated with sharp recanalization of SVC obstructions using the sharp end of a guidewire. 7 Fourteen of the 16 procedures were successful, however three major complications occurred, two of which included SVC perforation and hemopericardium.
The Guidewire Balloon Entrapment Technique (GBET) has been successfully used for tunnelled catheters placement in patients with right-sided central venous occlusions (TCVOs). A recent study by Bai et al. achieved a high success rate of 96.3% in 27 patients. 8 The first step involves placing a contrast filled balloon immediately distal to the occlusion from femoral access. Using orthogonal fluoroscopy the balloon is punctured with a micropuncture needle through the occluded vein from a percutaneous supraclavicular approach. Balloon decompression and contrast spill confirms needle position within the patent vein. A microwire is threaded into the punctured balloon. The microwire becomes ‘entrapped’ in the balloon and is pulled down through the inferior vena cava (IVC) and out the femoral sheath to establish through and through access. The wire is upsized and the occluded segment is dilated, allowing for catheter placement.
Balloon-Targeted Extra-Anatomic Sharp Recanalization is a separate balloon entrapment technique described by Choi et al. From femoral access either a 65 cm Chiba needle, stiff end of a hydrophilic wire or wire/catheter combination was used to pierce through the occlusion and into the extravascular soft tissues in the anterior soft tissues of the neck. The sharp instrument is exchanged over a wire for a 4–6 mm angioplasty balloon which is buried into the extravascular soft tissues at or above the clavicle and inflated. The balloon is punctured percutaneously using US, fluoroscopy or Cone beam CT (CBCT) guidance in the right supraclavicular fossa. An exchange length microwire is advanced into the balloon. The balloon and guidewire are retracted through the occlusion via the femoral sheath to establish through and through access. Choi et al. who described this technique, successfully used it in five cases to re-establish supraclavicular vascular access, four of which proceeded to HeRO graft placement. 9
Transvenous use of a 21-22G Chiba needle is a common technique for recanalizing occluded veins. This approach involves advancing a vascular sheath to the point of occlusion and then advancing a Chiba needle through the occlusion towards an intraluminal target. Studies by Cohen et al. and Gallo et al. demonstrate the effectiveness of this method. Cohen et al. reported a 95% success rate for recanalizing superior vena cava (SVC) obstructions in 39 patients. 10 Eleven of the patients in the series had temporary catheter placement for later conversion to HeRO graft. In this series there was two major complications, including hemopericardium and haemothorax. Gallo et al. achieved a 94% success rate in 36 patients using a 22G Chiba needle through an 18G coaxial needle and 5 Fr vascular sheath. 11 The coaxial needle was used to provide extra steerability. Twenty-nine of their 36 patients underwent catheter placement, 27 of which were later converted to HeRO grafts. One major complication (haemothorax) was encountered.
Radiofrequency wire is a unique technique for restoring central venous access. Radiofrequency pulses heat the tip of a wire, enabling it to burn through the obstruction rather than piercing through it. Dai and Kim reported its use in seven patients to bypass TCVO, achieving port placement in one and temporary central line placement (8 Fr) in the others for later conversion to HeRO graft. 12 The procedure, performed from femoral access, involves controlled perforation through the obstruction into the mediastinal fat using a radiofrequency wire or a stiff guidewire tip. Next, an angled catheter and guidewire form a broad J-loop to bluntly dissect through the mediastinal fat alongside the TCVO. Under multiplanar fluoroscopy the catheter is advanced towards an intraluminal target beyond the obstruction, and the radiofrequency wire then is used to perforate back into the true lumen. The wire is then snared allowing central venous catheter placement across through and through access.
The surfacer inside out access system (Bluegrass vascular Technologies, Texas) is a device specifically developed to restore central venous access across right sided TCVOs. The workstation sheath is advanced from the right femoral vein to abut the thoracic venous obstruction. Next, under multiplanar imaging the rigid surfacer device is forced in a centripetal direction through the obstruction until patent vein beyond the obstruction is reached. The device incorporates a side arm needle that is fired out of the vein and through the skin at an external radiopaque skin marker placed in the right supraclavicular fossa. A wire advanced from the needle establishes through and through access across the TVCO and allows placement of a peel away sheath and dialysis catheter placement. The SAVE trial reported a 97% (29/30 patients) success rate in establishing catheter access, without complication. 13 Notably over half of these patients had a complex Type 3-4 obstruction. The procedure had to be abandoned in one patient due to excessive iliac vein tortuosity which prevented introduction of the rigid device. Similarly Reindl-Schwaighofer et al. reported a 97% in success rate in 39 patients without complication. 14 The only technical failure was also due unsuitable iliofemoral anatomy.
The CT guided sharp recanalization technique described by Khalifa et al. and used in our institution offers certain advantages for interventionalist and patients. Firstly IVC and iliofemoral obstruction or tortuosity does not impede this technique. Operating from the right supraclavicular fossa provided better instrument steerability and control due to the close proximity of the TVCO compared to femoral access. This technique use readily accessible and cheap instruments available to most interventional departments. Perhaps most importantly, CT guidance facilitates precise and controlled needle placement, while ensuring clear visualization of critical mediastinal structures to reduce the risk of complication.
There are two disadvantages to this technique: the lack of real-time fluoroscopy in the CT room and the need to transfer the patient from CT to IR during the procedure. Performing the procedure in IR using cone-beam CT for vascular access, instead of conventional CT, may be a feasible alternative that addresses both of these issues. Nevertheless our current preference using conventional CT guidance is based on several factors. Firstly, our institution’s conventional CT system provides superior imaging quality compared to our cone-beam CT. This superior image quality is crucial for identifying critical structures and planning a safe route through the mediastinum. Additionally, we can sequentially track the needle tip as it is advanced in small increments through the mediastinum using three axial slice acquisitions on conventional CT. In our experience, this method is quicker and more precise than repeatedly acquiring cone-beam CT slabs.
As outlined in this review sharp recanalization carry significant risk and should be reserved for patients who have exhausted safer alternatives. Meticulous image guidance is essential to ensure careful manipulation of the sharp instrument in order to avoid injuring critical thoracic structures. Venous rupture and haemorrhage can also occur during tract dilation or venoplasty due to the noncompliant nature of the fibrous obstruction. Operators must be vigilant for and ready to manage potential complications including haemothorax, pneumothorax and hemopericardium with cardiac tamponade.
Conclusion
Restoring central venous access in haemodialysis patients with CVO can be extremely challenging. Sharp recanalization is an advanced, high risk procedure reserved for patients with exhausted access who have failed safer alternatives. A variety of sharp recanalization techniques now exist, the choice of which depends on local expertise and the resources available, type of obstruction and patient factors. CT guided sharp recanalization first described by Khalifa et al. has been used successfully in our institution to restore central venous access and facilitate HeRO graft placement. This is an important technique for interventionalists managing complex and long segment TCVO cases, especially in patients with unfavourable IVC and iliofemoral anatomy that precludes alterative techniques described.
Footnotes
Author contributions
All authors have contributed to authoring and reviewing this manuscript. All authors have reviewed and approved the manuscript for publication.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
Ethical approval
Informed consent was waived due to the retrospective use of pseudonymized data. Compliance with ethical aspects and data protection regulations was ensured. IRB approval was not required.
