Could it be advantageous to tune the temperature controller during radiofrequency ablation? A feasibility study using theoretical models

Purpose: To assess whether tailoring the Kp and Ki values of a proportional-integral (PI) controller during radiofrequency (RF) cardiac ablation could be advantageous from the point of view of the dynamic behaviour of the controller, in particular, whether control action could be speeded up and larger lesions obtained. Methods: Theoretical models were built and solved by the finite element method. RF cardiac ablations were simulated with temperature controlled at 55 degrees C. Specific PI controllers were implemented with Kp and Ki parameters adapted to cases with different tissue values (specific heat, thermal conductivity and electrical conductivity) electrode-tissue contact characteristics (insertion depth, cooling effect of circulating blood) and electrode characteristics (size, location and arrangement of the temperature sensor in the electrode). Results: The lesion dimensions and T(max) remained almost unchanged when the specific PI controller was used instead of one tuned for the standard case: T(max) varied less than 1.9 degrees C, lesion width less than 0.2 mm, and lesion depth less than 0.3 mm. As expected, we did observe a direct logical relationship between the response time of each controller and the transient value of electrode temperature. Conclusion: The results suggest that a PI controller designed for a standard case (such as that described in this study), could offer benefits under different tissue conditions, electrode-tissue contact, and electrode characteristics.This work received financial support from the Spanish 'Plan Nacional de I+D+I del Ministerio de Ciencia e Innovacion' Grant no. TEC2008-01369/TEC and FEDER Project MTM2010-14909. The translation of this paper was funded by the Universitat Politecnica de Valencia, Spain. The authors alone are responsible for the content and writing of the paperAlba Martínez, J.; Trujillo Guillen, M.; Blasco Giménez, RM.; Berjano Zanón, E. (2011). Could it be advantageous to tune the temperature controller during radiofrequency ablation? A feasibility study using theoretical models. International Journal of Hyperthermia. 27(6):539-548. https://doi.org/10.3109/02656736.2011.586665S539548276Gaita, F., Caponi, D., Pianelli, M., Scaglione, M., Toso, E., Cesarani, F., … Leclercq, J. F. (2010). Radiofrequency Catheter Ablation of Atrial Fibrillation: A Cause of Silent Thromboembolism? Circulation, 122(17), 1667-1673. doi:10.1161/circulationaha.110.937953Anfinsen, O.-G., Aass, H., Kongsgaard, E., Foerster, A., Scott, H., & Amlie, J. P. (1999). Journal of Interventional Cardiac Electrophysiology, 3(4), 343-351. doi:10.1023/a:1009840004782PETERSEN, H. H., CHEN, X., PIETERSEN, A., SVENDSEN, J. H., & HAUNSO, S. (2000). Tissue Temperatures and Lesion Size During Irrigated Tip Catheter Radiofrequency Ablation: An In Vitro Comparison of Temperature-Controlled Irrigated Tip Ablation, Power-Controlled Irrigated Tip Ablation, and Standard Temperature-Controlled Ablation. Pacing and Clinical Electrophysiology, 23(1), 8-17. doi:10.1111/j.1540-8159.2000.tb00644.xTungjitkusolmun, S., Woo, E. J., Cao, H., Tsai, J. Z., Vorperian, V. R., & Webster, J. G. (2000). Thermal—electrical finite element modelling for radio frequency cardiac ablation: Effects of changes in myocardial properties. Medical & Biological Engineering & Computing, 38(5), 562-568. doi:10.1007/bf02345754Lai, Y.-C., Choy, Y. B., Haemmerich, D., Vorperian, V. R., & Webster, J. G. (2004). Lesion Size Estimator of Cardiac Radiofrequency Ablation at Different Common Locations With Different Tip Temperatures. IEEE Transactions on Biomedical Engineering, 51(10), 1859-1864. doi:10.1109/tbme.2004.831529Jain, M. K., & Wolf, P. D. (1999). Temperature-controlled and constant-power radio-frequency ablation: what affects lesion growth? IEEE Transactions on Biomedical Engineering, 46(12), 1405-1412. doi:10.1109/10.804568Panescu, D., Whayne, J. G., Fleischman, S. D., Mirotznik, M. S., Swanson, D. K., & Webster, J. G. (1995). Three-dimensional finite element analysis of current density and temperature distributions during radio-frequency ablation. IEEE Transactions on Biomedical Engineering, 42(9), 879-890. doi:10.1109/10.412649Hong Cao, Vorperian, V. R., Tungjitkusolmun, S., Jan-Zern Tsai, Haemmerich, D., Young Bin Choy, & Webster, J. G. (2001). Flow effect on lesion formation in RF cardiac catheter ablation. IEEE Transactions on Biomedical Engineering, 48(4), 425-433. doi:10.1109/10.915708Tungjitkusolmun, S., Vorperian, V. R., Bhavaraju, N., Cao, H., Tsai, J.-Z., & Webster, J. G. (2001). Guidelines for predicting lesion size at common endocardial locations during radio-frequency ablation. IEEE Transactions on Biomedical Engineering, 48(2), 194-201. doi:10.1109/10.909640Schutt, D., Berjano, E. J., & Haemmerich, D. (2009). Effect of electrode thermal conductivity in cardiac radiofrequency catheter ablation: A computational modeling study. International Journal of Hyperthermia, 25(2), 99-107. doi:10.1080/02656730802563051Langberg, J. J., Calkins, H., el-Atassi, R., Borganelli, M., Leon, A., Kalbfleisch, S. J., & Morady, F. (1992). Temperature monitoring during radiofrequency catheter ablation of accessory pathways. Circulation, 86(5), 1469-1474. doi:10.1161/01.cir.86.5.1469Calkins, H., Prystowsky, E., Carlson, M., Klein, L. S., Saul, J. P., & Gillette, P. (1994). Temperature monitoring during radiofrequency catheter ablation procedures using closed loop control. Atakr Multicenter Investigators Group. Circulation, 90(3), 1279-1286. doi:10.1161/01.cir.90.3.1279Lennox CD, Temperature controlled RF coagulation. Patent number: 5.122.137 Hudson NHEdwards SD, Stern RA, Electrode and associated system using thermally insulated temperature sensing elements. Patent number: US Patent 5,456,682Panescu D, Fleischman SD, Whayne JG, Swanson DK, (EP Technology. Effects of temperature sensor placement on performance of temperature-controlled ablation. IEEE 17th Annual Conference, Engineering in Medicine and Biology Society, Montreal, Canada (1995)BLOUIN, L. T., MARCUS, F. I., & LAMPE, L. (1991). Assessment of Effects of a Radiofrequency Energy Field and Thermistor Location in an Electrode Catheter on the Accuracy of Temperature Measurement. Pacing and Clinical Electrophysiology, 14(5), 807-813. doi:10.1111/j.1540-8159.1991.tb04111.xBerjano, E. J. (2006). BioMedical Engineering OnLine, 5(1), 24. doi:10.1186/1475-925x-5-24Bhavaraju, N. C., Cao, H., Yuan, D. Y., Valvano, J. W., & Webster, J. G. (2001). Measurement of directional thermal properties of biomaterials. IEEE Transactions on Biomedical Engineering, 48(2), 261-267. doi:10.1109/10.909647Hong Cao, Tungjitkusolmun, S., Young Bin Choy, Jang-Zern Tsai, Vorperian, V. R., & Webster, J. G. (2002). Using electrical impedance to predict catheter-endocardial contact during RF cardiac ablation. IEEE Transactions on Biomedical Engineering, 49(3), 247-253. doi:10.1109/10.983459PETERSEN, H. H., & SVENDSEN, J. H. (2003). Can Lesion Size During Radiofrequency Ablation Be Predicted By the Temperature Rise to a Low Power Test Pulse in Vitro? Pacing and Clinical Electrophysiology, 26(8), 1653-1659. doi:10.1046/j.1460-9592.2003.t01-1-00248.xLANGBERG, J. J., LEE, M. A., CHIN, M. C., & ROSENQVIST, M. (1990). Radiofrequency Catheter Ablation: The Effect of Electrode Size on Lesion Volume In Vivo. Pacing and Clinical Electrophysiology, 13(10), 1242-1248. doi:10.1111/j.1540-8159.1990.tb02022.

A computational model for real-time calculation of electric field due to transcranial magnetic stimulation in clinics

The aim of this paper is to propose an approach for an accurate and fast (real-time) computation of the electric field induced inside the whole brain volume during a transcranial magnetic stimulation (TMS) procedure. The numerical solution implements the admittance method for a discretized realistic brain model derived from Magnetic Resonance Imaging (MRI). Results are in a good agreement with those obtained using commercial codes and require much less computational time. An integration of the developed codewith neuronavigation toolswill permit real-time evaluation of the stimulated brain regions during the TMSdelivery, thus improving the efficacy of clinical applications

Analysis of the 'Endoworm' prototype's ability to grip the bowel in in vitro and ex vivo models

[EN] Access to the small bowel by means of an enteroscope is difficult, even using current devices such as single-balloon or double-balloon enteroscopes. Exploration time and patient discomfort are the main drawbacks. The prototype 'Endoworm' analysed in this paper is based on a pneumatic translation system that, gripping the bowel, enables the endoscope to move forward while the bowel slides back over its most proximal part. The grip capacity is related to the pressure inside the balloon, which depends on the insufflate volume of air. Different materials were used as in vitro and ex vivo models: rigid polymethyl methacrylate, flexible silicone, polyester urethane and ex vivo pig small bowel. On measuring the pressure-volume relationship, we found that it depended on the elastic properties of the lumen and that the frictional force depended on the air pressure inside the balloons and the lumen's elastic properties. In the presence of a lubricant, the grip on the simulated intestinal lumens was drastically reduced, as was the influence of the lumen's properties. This paper focuses on the Endoworm's ability to grip the bowel, which is crucial to achieving effective endoscope forward advance and bowel foldingThe author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The study was funded by the Spanish Ministry of Economy and Competitiveness through Project (PI18/01365) and by the UPV/IIS LA Fe through the (Endoworm 3.0) Project. CIBER-BBN is an initiative funded by the VI National R&D&I Plan 2008-2011, Iniciativa Ingenio 2010, Consolider Program, CIBER Actions and financed by the Instituto de Salud Carlos III with the assistance of the European Regional Development FundTobella, J.; Pons-Beltrán, V.; Santonja, A.; Sánchez-Diaz, C.; Campillo Fernandez, AJ.; Vidaurre, A. (2020). Analysis of the 'Endoworm' prototype's ability to grip the bowel in in vitro and ex vivo models. Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine. 234(5):1-10. https://doi.org/10.1177/09544119209014141102345Iddan, G., Meron, G., Glukhovsky, A., & Swain, P. (2000). Wireless capsule endoscopy. Nature, 405(6785), 417-417. doi:10.1038/35013140Yamamoto, H., Sekine, Y., Sato, Y., Higashizawa, T., Miyata, T., Iino, S., … Sugano, K. (2001). Total enteroscopy with a nonsurgical steerable double-balloon method. Gastrointestinal Endoscopy, 53(2), 216-220. doi:10.1067/mge.2001.112181Arnott, I. D. R., & Lo, S. K. (2004). REVIEW: The Clinical Utility of Wireless Capsule Endoscopy. Digestive Diseases and Sciences, 49(6), 893-901. doi:10.1023/b:ddas.0000034545.58486.e6Hosoe, N., Takabayashi, K., Ogata, H., & Kanai, T. (2019). Capsule endoscopy for small‐intestinal disorders: Current status. Digestive Endoscopy, 31(5), 498-507. doi:10.1111/den.13346Fukumoto, A., Tanaka, S., Shishido, T., Takemura, Y., Oka, S., & Chayama, K. (2009). Comparison of detectability of small-bowel lesions between capsule endoscopy and double-balloon endoscopy for patients with suspected small-bowel disease. Gastrointestinal Endoscopy, 69(4), 857-865. doi:10.1016/j.gie.2008.06.007Akerman, P. A., Agrawal, D., Chen, W., Cantero, D., Avila, J., & Pangtay, J. (2009). Spiral enteroscopy: a novel method of enteroscopy by using the Endo-Ease Discovery SB overtube and a pediatric colonoscope. Gastrointestinal Endoscopy, 69(2), 327-332. doi:10.1016/j.gie.2008.07.042Moreels, T. G. (2017). Update in enteroscopy: New devices and new indications. Digestive Endoscopy, 30(2), 174-181. doi:10.1111/den.12920Pasha, S. F. (2012). Diagnostic yield of deep enteroscopy techniques for small-bowel bleeding and tumors. Techniques in Gastrointestinal Endoscopy, 14(2), 100-105. doi:10.1016/j.tgie.2012.02.001Lenz, P., & Domagk, D. (2012). Double- vs. single-balloon vs. spiral enteroscopy. Best Practice & Research Clinical Gastroenterology, 26(3), 303-313. doi:10.1016/j.bpg.2012.01.021Baniya, R., Upadhaya, S., Subedi, S. C., Khan, J., Sharma, P., Mohammed, T. S., … Jamil, L. H. (2017). Balloon enteroscopy versus spiral enteroscopy for small-bowel disorders: a systematic review and meta-analysis. Gastrointestinal Endoscopy, 86(6), 997-1005. doi:10.1016/j.gie.2017.06.015Menciassi, A., & Dario, P. (2003). Bio-inspired solutions for locomotion in the gastrointestinal tract: background and perspectives. Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 361(1811), 2287-2298. doi:10.1098/rsta.2003.1255Zarrouk, D., Sharf, I., & Shoham, M. (2011). Analysis of Wormlike Robotic Locomotion on Compliant Surfaces. IEEE Transactions on Biomedical Engineering, 58(2), 301-309. doi:10.1109/tbme.2010.2066274Poon, C. C. Y., Leung, B., Chan, C. K. W., Lau, J. Y. W., & Chiu, P. W. Y. (2015). Design of wormlike automated robotic endoscope: dynamic interaction between endoscopic balloon and surrounding tissues. Surgical Endoscopy, 30(2), 772-778. doi:10.1007/s00464-015-4224-8Kassim, I., Phee, L., Ng, W. S., Feng Gong, Dario, P., & Mosse, C. A. (2006). Locomotion techniques for robotic colonoscopy. IEEE Engineering in Medicine and Biology Magazine, 25(3), 49-56. doi:10.1109/memb.2006.1636351Kim, Y.-T., & Kim, D.-E. (2010). Novel Propelling Mechanisms Based on Frictional Interaction for Endoscope Robot. Tribology Transactions, 53(2), 203-211. doi:10.1080/10402000903125337Massalou, D., Masson, C., Foti, P., Afquir, S., Baqué, P., Berdah, S.-V., & Bège, T. (2016). Dynamic biomechanical characterization of colon tissue according to anatomical factors. Journal of Biomechanics, 49(16), 3861-3867. doi:10.1016/j.jbiomech.2016.10.023Egorov, V. I., Schastlivtsev, I. V., Prut, E. V., Baranov, A. O., & Turusov, R. A. (2002). Mechanical properties of the human gastrointestinal tract. Journal of Biomechanics, 35(10), 1417-1425. doi:10.1016/s0021-9290(02)00084-2Hoeg, H. D., Slatkin, A. B., Burdick, J. W., & Grundfest, W. S. (s. f.). Biomechanical modeling of the small intestine as required for the design and operation of a robotic endoscope. Proceedings 2000 ICRA. Millennium Conference. IEEE International Conference on Robotics and Automation. Symposia Proceedings (Cat. No.00CH37065). doi:10.1109/robot.2000.844825Terry, B. S., Passernig, A. C., Hill, M. L., Schoen, J. A., & Rentschler, M. E. (2012). Small intestine mucosal adhesivity to in vivo capsule robot materials. Journal of the Mechanical Behavior of Biomedical Materials, 15, 24-32. doi:10.1016/j.jmbbm.2012.06.018Kim, J.-S., Sung, I.-H., Kim, Y.-T., Kwon, E.-Y., Kim, D.-E., & Jang, Y. H. (2006). Experimental investigation of frictional and viscoelastic properties of intestine for microendoscope application. Tribology Letters, 22(2), 143-149. doi:10.1007/s11249-006-9073-0Lyle, A. B., Luftig, J. T., & Rentschler, M. E. (2013). A tribological investigation of the small bowel lumen surface. Tribology International, 62, 171-176. doi:10.1016/j.triboint.2012.11.018De Simone, A., & Luongo, A. (2013). Nonlinear viscoelastic analysis of a cylindrical balloon squeezed between two rigid moving plates. International Journal of Solids and Structures, 50(14-15), 2213-2223. doi:10.1016/j.ijsolstr.2013.03.028Sliker, L. J., Ciuti, G., Rentschler, M. E., & Menciassi, A. (2016). Frictional resistance model for tissue-capsule endoscope sliding contact in the gastrointestinal tract. Tribology International, 102, 472-484. doi:10.1016/j.triboint.2016.06.003Zhang, C., Liu, H., & Li, H. (2014). 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Preliminary Mechanical Characterization of the Small Bowel for In Vivo Robotic Mobility. Journal of Biomechanical Engineering, 133(9). doi:10.1115/1.400516

Geometry-based finite-element modeling of the electrical contact between a cultured neuron and a microelectrode

The electrical contact between a substrate embedded microelectrode and a cultured neuron depends on the geometry of the neuron-electrode interface. Interpretation and improvement of these contacts requires proper modeling of all coupling mechanisms. In literature, it is common practice to model the neuron-electrode contact using lumped circuits in which large simplifications are made in the representation of the interface geometry. In this paper, the finite-element method is used to model the neuron-electrode interface, which permits numerical solutions for a variety of interface geometries. The simulation results offer detailed spatial and temporal information about the combined electrical behavior of extracellular volume, electrode-electrolyte interface and neuronal membrane

Communication channel analysis and real time compressed sensing for high density neural recording devices

Next generation neural recording and Brain- Machine Interface (BMI) devices call for high density or distributed systems with more than 1000 recording sites. As the recording site density grows, the device generates data on the scale of several hundred megabits per second (Mbps). Transmitting such large amounts of data induces significant power consumption and heat dissipation for the implanted electronics. Facing these constraints, efficient on-chip compression techniques become essential to the reduction of implanted systems power consumption. This paper analyzes the communication channel constraints for high density neural recording devices. This paper then quantifies the improvement on communication channel using efficient on-chip compression methods. Finally, This paper describes a Compressed Sensing (CS) based system that can reduce the data rate by > 10x times while using power on the order of a few hundred nW per recording channel

Modeled channel distributions explain extracellular recordings from cultured neurons sealed to microelectrodes

Amplitudes and shapes of extracellular recordings from single neurons cultured on a substrate embedded microelectrode depend not only on the volume conducting properties of the neuron-electrode interface, but might also depend on the distribution of voltage-sensitive channels over the neuronal membrane. In this paper, finite-element modeling is used to quantify the effect of these channel distributions on the neuron-electrode contact. Slight accumulation or depletion of voltage-sensitive channels in the sealing membrane of the neuron results in various shapes and amplitudes of simulated extracellular recordings. However, estimation of channel-specific accumulation factors from extracellular recordings can be obstructed by co-occuring ion currents and defect sealing. Experimental data from cultured neuron-electrode interfaces suggest depletion of sodium channels and accumulation of potassium channels

Model estimation of cerebral hemodynamics between blood flow and volume changes: a data-based modeling approach

It is well known that there is a dynamic relationship between cerebral blood flow (CBF) and cerebral blood volume (CBV). With increasing applications of functional MRI, where the blood oxygen-level-dependent signals are recorded, the understanding and accurate modeling of the hemodynamic relationship between CBF and CBV becomes increasingly important. This study presents an empirical and data-based modeling framework for model identification from CBF and CBV experimental data. It is shown that the relationship between the changes in CBF and CBV can be described using a parsimonious autoregressive with exogenous input model structure. It is observed that neither the ordinary least-squares (LS) method nor the classical total least-squares (TLS) method can produce accurate estimates from the original noisy CBF and CBV data. A regularized total least-squares (RTLS) method is thus introduced and extended to solve such an error-in-the-variables problem. Quantitative results show that the RTLS method works very well on the noisy CBF and CBV data. Finally, a combination of RTLS with a filtering method can lead to a parsimonious but very effective model that can characterize the relationship between the changes in CBF and CBV