Retrograde Approach Research Articles

Retrograde artery first approach for "shoulder" pancreatic cancers in minimally invasive distal pancreatectomy.

"Shoulder" pancreatic cancer, defined as tumor located at the confluence where the splenic vein meets the portal vein, has specific adjacent anatomies. It's difficult to resect this type of tumor with adequate regional lymphadenectomy. We described a new concept of "shoulder" pancreatic cancer, and retrospectively analyzed eleven consecutive cases from September 2019 to April 2020, to assess the safety and efficacy of the retrograde artery first approach in minimally invasive distal pancreatectomy. The primary outcome was set as radical (R0) resection rate. All of the 11 cases achieved R0 resection, with a median of 8 (range 5-32) lymph nodes harvested, given the ratio of embraced splenic vein in 72.7% of the cases, splenic artery embracement in 45.5%, and SMV-PV wall invasion in 27.3%. The maximum tumor size on pathology was 35 (range 20-65)mm. The median operative time was 260 (range 155-470)min, and the median estimated blood loss was 200 (range 50-1000)ml. One case needed intraoperative transfusion. One grade B postoperative pancreatic fistula occurred accompanied with abdominal infection, while the rest of cases recovered uneventful. The median postoperative length of stay was 9 (range 6-20)days. "Shoulder" pancreatic cancers are clinically significant. Retrograde artery first approach is a potentially safe and effective alternative to achieve a radical resection margin for shoulder pancreatic cancers in minimally invasive era. More evidences are needed in the future.

Oral 31 - Antegrade and retrograde endoscopic approaches for managing obstructing ureteric calculi in renal transplant patients: An illustrative case series

Oral 31 - Antegrade and retrograde endoscopic approaches for managing obstructing ureteric calculi in renal transplant patients: An illustrative case series

Active Retrograde Extra Backup with a Mother-and-Child Catheter to Facilitate Retrograde Microcatheter Collateral Channel Tracking in Recanalization of Coronary Chronic Total Occlusion.

Objective To explore the feasibility and safety of the active retrograde backup (ARB) for treatment of chronic total occlusion (CTO) during retrograde percutaneous coronary intervention (PCI). Background Guiding support plays an important role in guidewire and microcatheter coronary channel (CC) tracking in retrograde PCI therapy for patients with CTO. However, the feasibility and safety of retrograde active use of a mother-and-child catheter are still unclear. Patients and Methods. A total of 271 consecutive patients with CTO who underwent retrograde PCI between January 2015 and January 2020 were retrospectively analyzed. Clinical data of two groups were compared to evaluate the feasibility and safety of ARB. Results Of the 271 patients, 69.0% (187/271) underwent therapy through the septal branch, 31.0% (84/271) through the epicardial collateral channel, and 47.6% (129/271) through active retrograde extra backup with a mother-and-child catheter to facilitate retrograde microcatheter collateral CC tracking. The time of wire CC tracking was shorter in the ARB group than that in the non-ARB group (25.4 ± 8.5 vs 26.4 ± 9.7, p=0.348), but there was no significant difference. The duration of the retrograde microcatheter tracking (10.2 ± 3.8 vs 15.5 ± 6.8, p=0.012) and the retrograde approach (62.8 ± 20.3 vs 70.4 ± 24.3, p=0.026) in the ARB group was significantly shorter than that in the non-ARB group. The radiation dose (223.6 ± 112.7 vs. 295.2 ± 129.3, p=0.028), fluoroscopy time (50.6 ± 21.3 vs 62.3 ± 32.1, p=0.030), and contrast volume (301.8 ± 146.7 vs 352.2 ± 179.5, p=0.032) in the ARB group were significantly lower than that in the non-ARB group. There were no life-threatening procedural complications in either group. Complications unrelated to ARB included two cases of donor-vessel dissection, one case of CC perforation, and two cases of target-vessel perforation. There was no statistically significant difference in major adverse cardiac and cerebrovascular events between the groups during hospitalization (p > 0.05). Conclusion ARB is feasible, safe, and conducive to guidewire and microcatheter CC tracking in the recanalization of coronary CTO. It improves procedural efficiency and is worthy of further promotion.

Rare complication of lateral abdominal wall hematoma after coronary angioplasty

Abdominal wall hematoma is a rare but potentially serious complication that may develop after percutaneous coronary interventional procedures. In particular, an oblique muscle hematoma caused by injury to the superficial circumflex iliac branch of the femoral artery is very rare. Most of these cases can be managed by conservative measures including hydration and blood component transfusion. However, when active bleeding continues, angiographic embolization or surgery might be needed. Here, we report an uncommon case of lateral abdominal wall hematoma following left femoral artery puncture during the performance of percutaneous coronary intervention by the retrograde approach in a totally occluded right coronary artery.

Digitalization of public governance and improvement of legal norms of appeals of service activity of public authorities in Ukraine

The purpose of the article. Describe the stages of development of regulatory and legal regulation of appeals against service activities of public authorities. Investigate theoretical scientific research in this area. Carry out the classification of normative legal acts and propose prospects for improving the current legislation in this area. Justify the need for progress in the provision of management services and determine the date of digitization of public administration.Scientific novelty. A comprehensive theoretical study of the need to change to service-oriented public policy in the field of management services. Needs to improve existing and develop new regulations to improve the mechanisms for appealing service activities, changes in bureaucratic approaches to the provision of service activities by public authorities. A scientific substantiation of the term "digitalization of public administration", the need to change the internal policy of the state in relation to the provision of management services as an effective dialogue in building civil society, as well as improving the quality of regulatory mechanisms for appealing service activities of public authorities.Conclusions. A study of the national development of legal regulation of appealing the results of service activities of public authorities found that it needs to update the retrograde approaches and strengthen control over the quality of development and implementation. An abrupt change is needed, as non-compliance with Ukraine’s binding international norms and effective European practices lacks time for evolution, leading to economic degradation and exacerbating the social crisis.

Transcatheter closure of ventricular septal defect from retrograde transarterial approach: immediate and long-term outcome

Background: Ventricular septal defect (VSD) is a commonly encountered congenital heart defect. The aim of this study was to analyze five years’ experience with patients who had undergone transcatheter closure of VSD using retrograde transarterial approach.Methods: It was a retrospective study conducted from December 2014 to December 2019. Cases planned for VSD closure in retrograde approach were included. A total of 147 cases fulfilled the criteria after left ventricular angiography and procedure was performed without forming arteriovenous loop. Follow up was planned at 1, 3, 6, 12 months and yearly thereafter.Results: The mean age of the patients was 5.94±4.67 years and mean weight was 17.93±8.26 kg. Perimembranous VSD was present in 70.06% cases and the size of the VSD was 5.5±1.8 mm. Amplatzer duct occluder II was the commonest device used (55.24%). Mean device size was 6.2±1.8 (5-8 mm). Complete occlusion was achieved immediately in 94.56% cases, and after one month in 99.36% cases. Four (2.78%) cases were postponed for malpositioning and encroachment of aortic valve. One patient (2.22%) had tiny residual VSD up to 3 years follow up. Bacterial endocarditis was noticed in one patient (0.80%) at one year follow up. No evidence of complete heart block was encountered in follow up period of six to 60 months.Conclusions: This study recommends that retrograde transarterial approach for closure of moderate to small VSD is safe, effective, and minimally invasive, can be performed in short time with less radiation hazard and less trauma to conducting tissues.

Tibial lengthening using a retrograde magnetically driven intramedullary lengthening device in 10 patients with preexisting ankle and hindfoot fusion

Background and purpose — Motorized intramedullary lengthening nails (ILNs) have been developed as an alternative to external fixators for long bone lengthening. The antegrade approach represents the standard method for tibial ILN insertion. In patients with preexisting ankle and hindfoot fusion a retrograde approach provides an alternative technique that has not been evaluated so far. We report the outcome of this method in 10 patients. Patients and methods — This retrospective study included 10 patients (mean age 18 years [13–25]) with preexisting ankle and hindfoot fusion who underwent tibial lengthening with a retrograde ILN (PRECICE). The mean leg length discrepancy (LLD) was 58 mm (36–80). The underlying conditions were congenital (n = 9) and post tumor resection (n = 1). The main outcome measures were: ILN reliability, distraction achieved, distraction index (DIX), time to bone healing, consolidation index (CIX), complications, and functional results. Results — All patients achieved the goal of lengthening (mean 48 mm [26–80]). Average DIX was 0.6 mm/day (0.5–0.7) and mean CIX was 44 days/cm (26–60). Delayed consolidation occurred in 2 patients and healed after ILN dynamization or nail exchange with grafting. Toe contractures in 2 other patients were resolved with physiotherapy or tenotomy. Until last follow-up (mean 18 months [12–30]) no true complications were encountered, knee motion remained unaffected, and full osseous consolidation occurred in all patients. Interpretation — In patients with LLD and preexisting ankle and hindfoot fusion distal tibial lengthening using a retrograde ILN is a reliable alternative to the standard approach with equivalent bone healing potential and low complication rates leaving the knee unaffected.

Left-sided accessory pathways successfully ablated from the aortomitral continuity region: distinctive atrial activation patterns and anatomic concerns.

Accessory pathways (APs) successfully ablated at the aortomitral continuity (AMC) were sporadically reported but relevant data are very limited. We aimed to describe the electrophysiological characteristics of AMC-AP and the related anatomy. This study involved eight (male/female = 3/5, mean age 42.6 ± 10.5 years) patients with left-sided AP successfully ablated in the AMC region. The retrograde atrial activation sequence was analysed and compared via recordings at the His-bundle (HB), coronary sinus (CS), and roving catheter during tachycardia, and the peak of QRS from the same cardiac circle used as time reference. Of the eight patients, two received prior ablations. During tachycardia, the activation time at the proximal CS (CSp), lateral CS (CSl), and HB region averaged 120 ± 26 ms, 124 ± 29 ms, and 117 ± 21 ms following the reference, respectively (P = 0.86). The latest atrial activation was recorded in the posterior CS which averaged 135 ± 25 ms following the reference. Placing the ablation catheter to AMC via retrograde approach was attempted in all cases but stable positioning achieved in none. Via transseptal approach, the ablation catheter could be easily placed at the AMC and recorded the earliest retrograde atrial activations with 60 ± 27 ms earlier than the relatively 'earliest' CS/HB recordings, and ablation at this site successfully eliminated AP conduction. No patients had recovered AP conduction after at least 12-month follow-up. AMC-AP is featured by recording comparable retrograde atrial activation times at CSp, CSl, and HB with the latest recordings at the posterior CS. Stable placement and successful ablation in the AMC via retrograde aortic approach was difficult but can be achieved via transseptal approach.

Endoscopic Orbital Reconstruction With Temporalis Muscle Flap.

Temporalis muscle flap is one of the most commonly used flaps in orbital reconstruction. Although multiple case series in the literature have reported elevation of the flap with an open incision and a retrograde approach from the periorbital region, to the best of the authors' knowledge, no studies have reported the use of an endoscopic method. Therefore, the authors' study presents endoscopy-assisted temporalis muscle reconstruction of a defect that occurred in the periorbital region following orbital exenteration. Minimal scarring and morbidity are some of the advantages of endoscopic methods, and healing without complications was achieved in our patient during the postoperative period. To the authors' knowledge, their study is the first to report the use of temporalis muscle flap in endoscopy-assisted periorbital reconstruction, which is a preferred method for endoscopic surgery.

Technical Feasibility and Safety of Percutaneous Coronary Intervention for True Ostial Left Anterior Descending Artery–Chronic Total Occlusion

BackgroundPercutaneous coronary intervention (PCI) for true ostial left anterior descending artery (LAD)–chronic total occlusion (CTO) lesions poses technical challenges owing to its inherent anatomic features. MethodsIn total, 270 consecutive patients who underwent PCI for ostial LAD-CTO at 13 major cardiac centers in South Korea were included. Ostial LAD-CTO was strictly defined as a LAD-CTO lesion whose proximal cap was within 1 mm from the carina of the distal left main coronary artery (LMCA) bifurcation. ResultsOstial LAD-CTOs were frequently accompanied by stumpless lesion entry (43.4%), whereas significant bending within the occluded segment was less frequent (14.4%). The overall technical success rate was 85.9%, and serious in-hospital adverse events occurred in 5.6%. The retrograde approach tended to contribute more frequently to success in patients with concomitant LMCA disease, stumpless CTO, interventional collaterals, and higher Japanese-CTO scores. Apparent dissection or hematoma requiring rescue procedure at the LMCA or left circumflex artery occurred in 14 patients (5.2%), with a higher tendency in patients who had LMCA disease (12.1% vs 4.2%) and stumpless entry (9.4% vs 2.0%) than in those without. Among patients who were successfully treated, with an average of 1.7 stents, target-vessel failure occurred in 23 patients (9.9%) during a median 3.3 years of follow-up. ConclusionsIn this first large-scale analysis of true ostial LAD-CTO, PCI was feasible with a high technical success rate and favourable mid-term outcomes. Clinically relevant inflow vessel injury can occur during PCI and should be an important technical consideration regarding safety.

Procedural and In-hospital Outcomes of Rotational Atherectomy in Retrograde Coronary Chronic Total Occlusion Intervention.

Coronary chronic total occlusions (CTOs) are characterized by a high incidence of severe plaque calcifications, which are associated with a high use of the retrograde approach and a low success rate of percutaneous coronary intervention (PCI). However, the feasibility of rotational atherectomy (RA) in retrograde CTO-PCI remains unknown. The aim of the present study is to examine the safety and efficacy of RA in retrograde CTO-PCI. Consecutive patients (n = 129) who underwent RA during CTO-PCI were categorized into anterograde and retrograde groups according to the CTO crossing approach. The distributions of the baseline characteristics were similar in the 2 groups, but the lesion type was more complex (P = .001), and the starting burr size was smaller (P = .003) in the retrograde group than in the anterograde group. There was a trend of a higher incidence of procedural complications in the retrograde group than in the anterograde group (P = .054). Technical and procedural success and in-hospital outcomes were not significantly different between the 2 groups. In conclusion, RA was feasible in retrograde CTO PCI, but some specific precautions are required before and during the procedure. In addition, further investigation of the long-term outcomes of RA in retrograde CTO PCI is necessary.

Mapping of the excitatory, inhibitory, and modulatory afferent projections to the anatomically defined active expiratory oscillator in adult male rats.

The lateral parafacial region (pFL ; which encompasses the parafacial respiratory group, pFRG) is a conditional oscillator that drives active expiration during periods of high respiratory demand, and increases ventilation through the recruitment of expiratory muscles. The pFL activity is highly modulated, and systematic analysis of its afferent projections is required to understand its connectivity and modulatory control. We combined a viral retrograde tracing approach to map direct brainstem projections to the putative location of pFL , with RNAScope and immunofluorescence to identify the neurochemical phenotype of the projecting neurons. Within the medulla, retrogradely-labeled, glutamatergic, glycinergic and GABAergic neurons were found in the ventral respiratory column (Bötzinger and preBötzinger Complex [preBötC], ventral respiratory group, ventral parafacial region [pFV ] and pFL ), nucleus of the solitary tract (NTS), reticular formation (RF), pontine and midbrain vestibular nuclei, and medullary raphe. In the pons and midbrain, retrogradely-labeled neurons of the same phenotypes were found in the Kölliker-Fuse and parabrachial nuclei, periaqueductal gray, pedunculopontine nucleus (PPT) and laterodorsal tegmentum (LDT). We also identified somatostatin-expressing neurons in the preBötC and PHOX2B immunopositive cells in the pFV , NTS, and part of the RF. Surprisingly, we found no catecholaminergic neurons in the NTS, A5 or Locus Coeruleus, no serotoninergic raphe neurons nor any cholinergic neurons in the PPT and LDT that projected to the pFL . Our results indicate that pFL neurons receive extensive excitatory and inhibitory inputs from several respiratory and nonrespiratory related brainstem regions that could contribute to the complex modulation of the conditional pFL oscillator for active expiration.

Efficacy and Safety of Angiography-Guided Retrograde Posterior Popliteal Puncture Technique in the Supine Position

Various techniques are needed for successful treatment of femoropopliteal long chronic total occlusion (CTO). Previous reports have described popliteal puncture by duplex echo guidance, but the safety of angiography-guided popliteal puncture remains unclear. This study was performed to examine the efficacy and safety of angiography-guided retrograde posterior popliteal puncture in the supine position. We analyzed 44 consecutive patients treated with retrograde femoropopliteal puncture for femoropopliteal CTO from October 2013 to February 2019. We compared 24 patients who underwent angiography-guided posterior popliteal puncture (posterior group) and 20 patients who underwent frontal superficial femoral artery/popliteal artery puncture (frontal group). The primary end point was successful revascularization. The secondary end points were the puncture time, hemostasis time, and procedure-related complications. The posterior group tended to have a higher procedural success rate than the frontal group (100% vs. 90.0%, respectively; P=0.20). The hemostasis time was significantly shorter in the posterior than frontal group (527.1±146.5 vs. 710.0±337.8sec, respectively; P=0.021). There was no significant difference in the puncture time between the posterior and frontal groups (8.19±9.22 vs. 7.50±9.68min, respectively; P=0.81). Both groups had a low complication rate (posterior, 0.0% vs. frontal, 5.0%; P=0.4). Angiography-guided posterior popliteal puncture in the supine position can facilitate hemostasis and may improve the success rate of the procedure. This technique may contribute to the treatment of complex femoropopliteal CTO as one option for a retrograde approach.

Contemporary Techniques of Prostate Dissection for Robot-assisted Prostatectomy

BackgroundOver the years, several techniques for performing robot-assisted prostatectomy have been implemented in an effort to achieve optimal oncological and functional outcomes. ObjectiveTo provide an evidence-based description and video-based illustration of currently available dissection techniques for robotic prostatectomy. Design, setting, and participantsA literature search was performed to retrieve articles describing different surgical approaches and techniques for robot-assisted radical prostatectomy (RARP) and to analyze data supporting their use. Video material was provided by experts in the field to illustrate these approaches and techniques. Surgical procedureMultiple surgical approaches are available: extraperitoneal, transvesical, transperitoneal posterior, transperitoneal anterior, Retzius sparing, and transperineal. Surgical techniques for prostatic dissection sensu strictu are the following: omission of the endopelvic fascia dissection, bladder neck preservation, incremental nerve sparing by means of an antegrade or retrograde approach, and preservation of the puboprostatic ligaments and dorsal venous complex. Recently, techniques for total or partial prostatectomy have been described. MeasurementsDifferent surgical approaches and techniques for robotic prostatectomy have been analyzed. Results and limitationsTwo randomized controlled trials evaluating the extraperitoneal versus the transperitoneal approach have demonstrated similar results. Level I evidence on the Retzius-sparing approach demonstrated earlier return to continence than the traditional anterior approach. The question whether Retzius-sparing RARP is associated with a higher rate of positive surgical margins is still open due to the intrinsic bias in terms of surgical expertise in the available comparative studies. This technique also offers an advantage in patients who have received kidney transplantation. Retrospective evidence suggests that the more the anatomical dissection (eg., more periprostatic tissue is preserved), the better the functional outcome in terms of continence. Yet, two randomized controlled trials evaluating the different techniques of dissection have so far been produced. Partial prostatectomies should not be offered outside clinical trials. ConclusionsSeveral techniques and approaches are available for prostate dissection during RARP. While the Retzius-sparing approach seems to provide earlier return to continence than the traditional anterior transperitoneal approach, no technique has been proved to be superior to other(s) in terms of long-term outcomes in randomized studies. Patient summaryWe have summarized available approaches for the surgical treatment of prostate cancer. Specifically, we described the different techniques that can be adopted for the surgical removal of the prostate using robotic technology.

Future strategies to enhance kidney preservation in upper urinary tract urothelial carcinoma.

Though radical nephroureterectomy remains the gold standard treatment for high grade or invasive disease in upper tract urothelial cancer (UTUC), kidney-sparing surgery has become preferred for low risk disease, in order to minimize morbidity and preserve renal function. Many methods exist for endoscopic management, whether via an antegrade percutaneous or retrograde ureteroscopic approach, including electroresection, laser ablation, and fulguration. There has been an increase in use of adjuvant intracavitary therapy, predominantly using mitomycin and bacillus Calmette-Guerin (BCG), to reduce recurrence after primary endoscopic management for noninvasive tumors, although efficacy remains questionable. Intraluminal BCG has additionally been used for primary treatment of CIS in the upper tract, with around 50% success. Newer investigations include use of narrow band imaging or photodynamic diagnosis with ureteroscopy to improve visualization during diagnosis and treatment. Genomic characterization may improve selection for kidney-sparing surgery as well as identify actionable mutations for systemic therapy. The evolution in adjuvant management has seen strategies to increase the dwell time and the urothelial contact of intraluminal agents. Lastly, chemoablation using a hydrogel for sustained effect of mitomycin is under investigation with promising early results. Continued expansion of the armamentarium available and better identification and characterization of tumors ideal for organ-sparing treatment will further improve kidney preservation in UTUC.

Antegrade Double-J Stenting in Grossly Dilated and Tortuous Ureters

AbstractFailure of retrograde approach for ureteric stenting warrants percutaneous nephrostomy with antergrade stenting to relieve the pressure symptoms and prevent the need for external drainage. However, in some tight ureteric strictures with grossly dilated tortuous ureter it may not be possible to navigate a ureteric stent across. In such instances pull through or rendezvous techniques have been advocated. Here, we have illustrated simple and novel techniques for traversing tortuous ureters with tight strictures. In one instance, a guide wire was snared via the perurethral approach and the system stabilized from both ends; the flexometallic sheath was then advanced into the urinary bladder across the stricture and a ureteric stent was deployed. In the other situation where the ureter was very tortuous, plain twisting and turning maneuver with retraction of whole assembly was done to straighten the ureter followed by advancement of the flexometallic sheath and stationing of the ureteric stent. In both the cases no significant procedure-related complications were seen and patients were discharged in stable condition. Our experience has led us to believe that occasionally all facilities may not be accessible immediately or the desired armamentarium may be unavailable for interventional radiologists, especially when the patient is on the table; in such cases, simple improvisation and techniques can come in handy to place a ureteric stent across a dilated tortuous ureter.

Myocardial protection in cardiac surgery: how limited are the options? A comprehensive literature review.

For patients undergoing cardiopulmonary bypass, myocardial protection is a key for successful recovery and improved outcomes following cardiac surgery that requires cardiac arrest. Different solutions, components and modes of delivery have evolved over the last few decades to optimise myocardial protection. These include cold and warm and blood and crystalloid solution through antegrade, retrograde or combined cardioplegia delivery approach. However, each method has its own advantages and disadvantages, posing a challenge to establish a gold-standard cardioplegic solution with an optimised mode of delivery for enhanced myocardial protection during cardiac surgery. The aim of this review is to provide a brief history of the development of cardioplegia, explain the electrophysiological concepts behind myocardial protection in cardioplegia, analyse the current literature and summarise existing evidence that warrants the use of varying cardioplegic techniques. We provide a comprehensive and comparative overview of the effectiveness of each technique in achieving optimal cardioprotection and propose novel techniques for optimising myocardial protection in the future.

Retrograde gene transfer into neural pathways mediated by adeno-associated virus (AAV)-AAV receptor interaction

BackgroundViral vector systems delivering transgenes in the retrograde direction through axons to neural cell bodies are powerful experimental tools for the functional analysis of specific neural pathways. Generally, the efficiency of viral vector-mediated retrograde gene transfer depends on the expression of requisite viral receptors in neural pathways projecting to the viral vector-injected regions. This is known as viral tropism and can limit the utility of retrograde viral vectors. The adeno-associated virus (AAV) vector has become an increasingly popular platform for gene delivery to neural cells in vivo, and it is therefore meaningful to develop a new type of retrograde gene transfer approach based on a tropism-free AAV vector system. New MethodThe wild-type or mutant receptor gene of AAV was expressed to mitigate AAV tropism. ResultsEfficient AAV vector-mediated retrograde gene transfer was observed in diverse neural pathways by expression of the AAV receptor (AAVR) gene. Moreover, the expression of a minimal mutant of AAVR (miniAAVR), which maintains binding potential to AAV, demonstrated efficient retrograde gene expression comparable to that of AAVR. Comparison with Existing MethodsThe utility of existing AAV vector-mediated retrograde gene delivery methods is sometimes limited by tropism. Our newly developed AAV-AAVR and AAV-miniAAVR interaction approaches enabled efficient retrograde gene transfer into various neural pathways by mitigating tropism. ConclusionsAAV-AAVR and AAV-miniAAVR interaction approaches enabled us to induce efficient retrograde gene expression in targeted neural pathways and provide a powerful tool for analyzing specific neural pathways.

Tibiopedal and distal femoral retrograde vascular access for challenging chronic total occlusions: predictors for technical success, and complication rates in a large single-center cohort

ObjectiveTo evaluate the safety and effectiveness of tibiopedal and distal femoral access for retrograde crossing of chronic total occlusion (CTO) in Rutherford stage III to VI peripheral arterial occlusive disease, and to determine factors that correlate with technical success.Material and methodsOne hundred seventy-one consecutive patients were included in this retrospective study. Rutherford stages were III, IV, and V/VI in 24%, 8%, and 67% of patients. Inclusion criteria were CTO at the superficial femoral (SFA), popliteal (PA), and/or below-the-knee (BTK) level, and a failed antegrade treatment followed by a distal retrograde approach. The numbers of occluded vascular levels (OVL), lesion length, degree of calcification, technical success rate, complications, and clinical outcome were noted.ResultsOVL were 1 in 72%, 2 in 20%, and 3 in 8% of patients. CTOs were longer than 20 cm in 45.6% of cases and showed severe calcifications in 50.3%. Target vessels for distal access were the distal SFA/PA in 17% and BTK in 83%. The overall technical success rate was 82%. Severe calcification decreased technical success (p = 0.01) despite lesion length and Rutherford stage. Clinical outcome improved in 123/152 patients with a significant increase of the median ABI (N = 158) from 0.53 (interquartile range 0.39 to 0.61) to 0.85 (0.59 to 1.03; p < 0.001). Complications were reported in 7.6% cases with 2.3% related to the distal vascular access.ConclusionThe tibiopedal and distal femoral retrograde access presents a safe and effective treatment option of CTOs at the thigh and/or BTK after a failed antegrade attempt improving clinical outcome. Technical success decreased with lesion’s degree of calcification.Key Points• Safety and effectiveness of the tibiopedal and distal femoral access for retrograde crossing of chronic total occlusion.• Target lesion’s degree of calcification decreases technical success.• Complications related to the distal vascular access were rare.

Transient Performance of &amp;gt;10kV SiC IGBT with an Optimized Retrograde p-Well

The impact of different p-well designs upon the transient performance, in particular, the turn-off losses and short-circuit capability, of a &gt;10 kV SiC n-IGBT is assessed. We find that in addition to improved transient performance, a substantial reduction in the depth of p-well implants can be achieved, if an extensively optimized retrograde approach is utilized. A conventional p-well consisting of a uniformly doped deep implant (doping concentration of ~3×1017 cm-3 and depth of &gt;1.5 µm) exhibits considerable turn-off switching losses without offering any short circuit capability. However, an optimized retrograde p-well consisting of a variable doping profile and depth as shallow as 0.7-0.8 µm results in much reduced turn-off losses with excellent short-circuit capability. Shallow implants are desirable to lower the development cost and processing challenges. The retrograde p-well is therefore highly promising for the development of &gt;10 kV class of SiC IGBTs.