The feasibility and safety of a through-and-through wire technique for central venous occlusion in dialysis patients

CVOD is the most common major problem encountered in vascular access [6–8]. Without a timely and effective management, CVOD usually results in a decrease in longevity and quality of life in patients.

Currently, endovascular therapy is the preferred method for treating CVOD, because surgical options are associated with significant morbidity and are used as alternative treatments only for patients refractory to percutaneous endovascular treatment. However, reported technical success rates, complications, and long-term outcomes of endovascular therapy varied greatly [1, 6, 9–14], which can be attributed to differences in recanalizing technique, study methodologies, patient demography, and certain characteristics of obstructive lesions including size and elasticity, as well as the degree of obstruction [1–4, 11, 15]. According to reports, technical success rates have been shown to have a range from 70% to 100% [1, 16]. However, we noted that clinical practice guidelines, such as the Kidney Disease Outcomes Quality Initiative (KDOQI) and the European Best Practice Guidelines (EBPG), were developed in 2002–2006 in developed countries [17, 18]. Therefore, in these countries, CVOD can be diagnosed and treated timely. Although not all CVS need to be addressed, because some studies suggest that there is no close correlation between CVS-induced abnormal hemodynamic changes and clinical symptoms and only 33% of CVS patients manifest clinically, [19]. There is no controversy about the necessity of complete occlusion of central vein (CVOD) with symptoms.

In China, there are currently no general guidelines for the monitoring of hemodialysis patients. Therefore, COVD is rarely diagnosed until patients are unable to receive hemodialysis via vascular access or have severe upper limb edema that significantly affects daily life, which led to a situation in which most CVS patients had progressed to completely occlusion. It makes us available to screen the enough patients with complete vascular occlusion rigidly [20, 21]. Different from most of previous studies in which CVOD was defined as 50% stenosis and/or actually included some CVS patients, our definition of CVOD was strictly defined as complete vascular occlusion, where the original blood flow of outflow vein is completely blocked before treatment [22].

Endovascular treatment of CVOD or CVS has been previously reported, but the factors limiting technical success received little attention [6–14]. Our study analyzed the technical aspects in the cases of technical failure and found two major aspects accounting for technical success. These two aspects were “crossing” and “revascularization.” Crossing is to pass the guidewire through the occlusion, and revascularization is to position the balloon and stent and angioplasty on the occluded site. “Crossing” has been recognized as key for technical success as previous reports. The difficulty of crossing the wire is related to certain characteristics of obstructive lesions including size and elasticity. There are three methods to tackle this issue: blunt crossing, sharp crossing, and balloon puncture crossing [10–13, 23, 24]. As long as the guidewire crosses the occlusion, the channel for recanalization is established, and the second step will follow. There are many ways for the balloon and stent to advance through the occlusion, including the replacement of super stiff guidewire, use of a long sheath, and flossing wire techniques. The occlusion length, extent and location are main factors influencing the resistance to passing the balloon through the occlusion. Our study showed that this second step of the operation was also the key to the success of the intervention. For instance, in all 34 successful cases in two groups, the entire average fluoroscopy time was 101 min, of which the first step took an average of 57 min, and the second step took an average of 41 min, accounting for 56% and 40% of the entire operation time, respectively. Second, in 9 of 15 cases of treatment failure, the first step was not completed, and 6 cases did not pass the second step, accounting for 60% and 40% of the total failure number, respectively. Thus, the second step contributed significantly to the overall operation time and the failure rate. In addition, based on the literature and our study, during the wire-crossing process, the actual use of a sharp crossing or balloon puncture technique was not frequent in successful cases. In 40 cases with successful crossing the wire (i.e., the first step), 2 cases had a sharp crossing technique. However, in 9 cases which failed, 1 used a sharp crossing. In 14 successful cases reported by Kundu et al., only 1 case used a sharp needle [25]. Therefore, we believe that using a sharp crossing technique had no significant impact on the overall success rate, because it was not frequently needed in the cases reported. In contrast, in the second step, a single approach super-stiff guidewire replacement and long sheath support assistive technologies were used for some of our patients, and a flossing wire technique was used for some others. Only the latter obtained a 100% success rate, suggesting that the flossing wire technique is the most effective measure to solve difficulties encountered during the second step. In addition, although some patients showed failure in the first technique and were successfully switched to the second, these patients were not included in this study to avoid interference by data duplication.

The flossing wire technique was reported to treat central venous occlusion in 1996, and has been consistently used since then [26–30]. In previous reports, the flossing wire technique was not listed as an individual technique but was used in handling complicated cases, as reported by Kundu and Haage [25, 31]. In our study, this technique was used for 30 patients, and we obtained and analyzed more data related to the use of this technique. Our findings suggest that flossing wire technology significantly reduced fluoroscopy time, and obtained a high success rate and low complication rates.

Our findings suggest that the use of the flossing wire technique can increase the surgical success rate through a better approach to handle the issue of balloon crossing the occlusion, which may be attributable to the following aspects: first, it solves the issue occurring when a wire guiding balloon through the occlusion meets resistance, rolls back, and is twisted. The length of the occluded segment is considered as the primary factor affecting the technical success rate; it affects both guidewire crossing the occlusion and balloon catheter crossing stenosis [32]. However, for the time being, no unified length-measurement method has been adopted. We used a synchronous bilateral fluorescein imaging technique to determine the length of the occluded segment, which fully presented the original information of the occluded segment prior to intervention. Our studies have shown that 6.5 cm is a critical length of occluded segment for a unidirectional technique approach. If the occlusion is longer than 6.5 cm, treatment success rate will be significantly compromised, because the long occluded segment increases the resistance to a certain level, such that the forced advance of the guidewire and balloon catheter will be rolled back and twisted. In our unidirectional technique group, 8 cases of failure had a length of occlusion longer than 6.5 cm, of which 4 cases failed during second step. Some studies used long sheaths to increase the chance of success [10, 25] as we did in our study. However, we did not succeed with this approach in patients with a large lumen diameter of blood vessel localized before and after the occluded segment. In addition, when the occlusion occurs at the turning point, direction change is the factor that resists the advance of balloon catheter, because a long sheath only increases propulsion but does not provide steering force. Flossing guidewire technology has the advantage of offering sufficient propulsion and steering force, which is the major reason why endovascular treatment has been widely used in recent years. For example, the flossing guidewire technique is efficient and useful to guide the stent through the places of extreme bending, such as the aortic arch in aortic dissection, usually referred to as the “Gothic arch” [3, 33–35]. The “Gothic arch” also exists in the central venous structures. To pass a balloon through the “Gothic arch” occlusion without the guiding force provided by the stretching guidewire is difficult, and it will also be difficult for those stents with poor compliance, the latter of which may steer away from the original direction and may hence pierce the wall of the blood vessel. Our preliminary data showed that for the lesions in certain places, such as the right innominate vein, the cross-left innominate vein, or the superior vena cava, using through-and-through technology tended to achieve a higher success rate.

In addition, the data from the follow-up with the patients with successful operations in these two groups showed no significant differences in the primary patency rates (%) and secondary patency rates (%). Thus, from the technical point of view, the improved flossing guidewire technique did not affect the long-term therapeutic effects of the patients who had been treated successfully. However, the flossing wire technique has advantages with regards to short-term complications. The unidirectional technique approach has two options, from either the proximal or the distal end of the occluded segment. For the occlusion of the long segment, performing recanalization from the distal end is preferred because the distance is shorter and the operation is more controllable [10, 14]. This approach usually takes a shunt or draining vein as a channel for the import of various interventional devices, and requires a catheter sheath with a size of 8Fr or even larger, which has a high risk of generating hematoma [36]. Although the pressure of the shunt and outflow vein differs in AVF and AVG. The effective ?P in the fistula generally is only 8 to10 mm Hg, frequently 25%, and seldom more than half those noted in grafts [17]. Given that many patients with kidney diseases have hypertension, hemostasis should be implemented timely and efficiently and should be given sufficient amount of time after the sheath pullout. Under the impact of extreme edema of the lesion, hemostasis performed actually will not be the same as that achieved by artery pressing. Vascular closure devices may reduce the incidence of hematoma, but may also theoretically increase the risk of draining vein stenosis [9]. In our flossing wire approach, we introduced catheter and wire through the distal access with a 4Fr vascular sheath, which significantly reduced the damage to the vascular access. We usually chose the femoral vein as another access with an 8fr or even larger vascular sheath to the balloon and stent. Femoral vein access is generally recognized as a safe passage, and the use of a large sheath has no impact on dialysis. Therefore, we did not see complications such as hematoma and dialysis access occlusion, as observed in the unidirectional technique procedure.

In the present study, we also found that the flossing wire technique had shorter fluoroscopy time than the unidirectional technique approach during the full treatment period, although it was required to generate two vascular access sites, because the guidewire stretching saved time during the second step. Using the flossing guidewire technique, the stent was managed to cross the occlusion and deployed directly. By contrast, using the unidirectional technique approach, in order to ensure that the stent crosses the occlusion and is positioned smoothly, a small balloon is usually needed for pre-dilation. Therefore, in the second part of the procedure, the flossing guidewire technique is actually succinct.