Technical advance in silico and in vitro development of a new bipolar radiofrequency ablation device for renal denervation

Background Renal denervation with radiofrequency ablation has become an accepted treatment for drug-resistant hypertension. However, there is a continuing need to develop new catheters for high-accuracy, targeted ablation. We therefore developed a radiofrequency bipolar electrode for controlled, targeted ablation through Joule heating induction between 60 and 100 °C. The bipolar design can easily be assembled into a basket catheter for deployment inside the renal artery. Methods Finite element modeling was used to determine the optimum catheter design to deliver a minimum ablation zone of 4 mm (W) × 10 mm (L) × 4 mm (H) within 60 s with a 500 kHz, 60 Vp-p signal, and 3 W maximum. The in silico model was validated with in vitro experiments using a thermochromic phantom tissue prepared with polyacrylamide gel and a thermochromic ink additive that permanently changes from pink to magenta when heated over 60 °C. Results The in vitro ablation zone closely matched the size and shape of the simulated area. The new electrode design directs the current density towards the artery walls and tissue, reducing unwanted blood temperature increases by focusing energy on the ablation zone. In contrast, the basket catheter design does not block renal flow during renal denervation. Conclusions This computational model of radiofrequency ablation can be used to estimate renal artery ablation zones for highly targeted renal denervation in patients with resistant hypertension. Furthermore, this innovative catheter has short ablation times and is one of the lowest power requirements of existing designs to perform the ablation.

The Performance of a Spherical-tip Catheter for Stent Post-dilation: Finite Element Analysis and Experiments

At present, percutaneous coronary intervention (PCI) is the most effective treatment of coronary artery stenosis. However, in case post-dilation of the stent is needed, the tip of the commonly used post-dilation balloon catheter cannot always pass through the stent smoothly, especially when it is situated in the curved part of the vessel. To improve the performance of traditional post-dilation balloon catheter, a preliminary design of a novel catheter with a spherical-tip is proposed. Since the performance of this spherical-tip catheter is still unclear, in this study, finite element analysis (FEA) and experimental validation of blood vessel with different curvature radii were performed to test and evaluate the performance of the spherical-tip catheter design. The comparative results between the two types of catheters demonstrate that in the simulated post-dilation process, the spherical-tip catheter is easier to pass through the stent placed in the curved vessel without the deformation of the stent strut, and can theoretically reduce the operation time and improve the safety of the operation. Furthermore, the strong consistency between simulation and experiment indicates that the finite element (FE) model can be a helpful tool for future optimization and evaluation of novel catheters, so as to save time and budget in product development and reduce/replace animal studies.

First-in-human experience of the Bashir Endovascular Catheter in the treatment of iliocaval deep vein thrombosis

Deep vein thrombosis (DVT) is a common disorder affecting approximately 900,000 new patients in the United States each year. Although the mainstay of treatment of DVT patients is therapeutic anticoagulation, some patients remain significantly symptomatic and therefore require more advanced interventions such as catheter-directed thrombolysis (CDT). We describe a case series of 13 patients with acute symptomatic inferior vena cava (IVC) and iliofemoral DVT that were treated with CDT using the Bashir Endovascular Catheter (BEC). We report the first-in-human use of BEC, which is a novel pharmacomechanical thrombolysis device. All the treated patients had complete and rapid resolution of their symptoms with excellent venous outflow. Despite initial promising results, larger studies using this catheter design will be needed to assess the role of BEC-directed therapy on rates of post-thrombotic syndrome and bleeding complications.

Technical and procedural comparison of two different cryoballoon ablation systems in patients with atrial fibrillation

Purpose The aim was to report procedural and technical differences of a novel cryoballoon (NCB) ablation catheter for pulmonary vein isolation (PVI) compared to the standard cryoballoon (SCB) catheter. Methods Consecutive patients with atrial fibrillation (AF) undergoing PVI using the NCB and the SCB were included. Procedural parameters, technical differences, acute efficacy, and safety are reported. Results Eighty patients (age 66 ± 10 years, ejection fraction 57 ± 10%, left atrial volume index 40 ± 6 ml/m2) were studied. With the NCB, 156 of 158 PVs (99%) were isolated compared to isolation of 159 of 159 PVs (100%) with the SCB. The median number of freezes in the NCB and the SCB group was 6 (IQR 5–8) and 5 (IQR 4–7), respectively (p = 0.051), with 73% and 71% of the PVs isolated with a single freeze, respectively. Nadir temperature and temperature at isolation were − 59 ± 6 °C and − 45 ± 17 °C in the NCB group and − 46 ± 7 °C and − 32 ± 23 °C in the SCB group, respectively (both p < 0.001) with no difference in time to isolation (TTI). Procedural differences were observed for the total procedure time (84 ± 29 min in the NCB group and 65 ± 17 min in the SCB group, p = 0.003). There was a peri-procedural stroke in one patient in the NCB group. Differences in catheter design were observed that may account for the differences in temperature recordings and ice cap formation. Conclusions Acute efficacy and TTI were similar with the NCB compared to the SCB. Measured temperatures were lower with the NCB, most likely due to differences in catheter design.

Microsurgery in the Netherlands, from an experimental pharmacological perspective

This paper is dedicated to the memory of Hans Rensema (1948–2020), medical artist of Microsurgical Developments Foundation.The history of training in microsurgical and experimental techniques in the Netherlands goes back to the 1960s. The training was mostly done on an individual basis. Clinical surgeons could benefit from the 'Wet-Lab' training at the Erasmus University of Rotterdam. Experimental microsurgery and techniques training for larger groups of bio-technicians and researchers started at Utrecht University in 1993, and later at Groningen University. The first commercial training was offered at the International Microsurgical Training Centre in Lelystad (IMTC,) in 2002. This paper presents the current state-of-the-art training in the Netherlands and some future perspectives.Professor Remie studied Pharmacy at the University of Groningen. After completing his studies in 1983, he specialised in pharmacology and did his PhD on the presynaptic modulation of noradrenergic neurotransmission in the freely moving rat portal vein. He joined Solvay Pharmaceuticals as a Group leader in Pharmacology, specialized (1991) in Laboratory Animal Science (Utrecht University), and became Laboratory Animal Scientist and Animal Welfare Officer of Solvay Pharmaceuticals and Fort Dodge Animal Health Holland. He is chairman of the Microsurgical Developments Foundation and several IACUCs. From 1997 until 2012, he was appointed professor with a special chair in Microsurgery and Experimental Technique in Laboratory Animals at the Groningen Centre for Drug Research, Department of Biomonitoring & Sensoring, University Centre for Pharmacy, University of Groningen. He is CEO of 3-R's Training Centre BV, and Director of the René Remie Surgical Skills Centre (www.rrssc.eu).Irene Cuesta Cobo earned a BSc in Biology and physiotherapy, and an MSc in manual therapy at the University of Jaén (Spain). She worked at the department of physiology at the same university on an in-vivo assay with gliomas in rats and subsequently, at the Laboratory of CAR Madrid to analyse top athletes' blood samples. She is a senior instructor at RRSSC.Edwin Spoelstra earned an MSc in Pharmacy and specialised stereotaxic surgery and microdialysis in the rat. He developed several techniques in mice and spent the last ten years on catheter design and blood-sampling.