Contact Force–Sensing Catheters

Abstract

R adiofrequency catheter ablation was initially developed to treat arrhythmias dependent on a narrow isthmus, such as accessory pathway-mediated tachycardias or atrioventricular nodal reentry. Although catheter stability was often discussed as important before delivering radiofrequency energy, adjusting the catheter and delivering another lesion could often rectify an inadequate result. The advent of wide area circumferential or linear ablation for the treatment of atrial fibrillation (AF) and ventricular tachycardia has raised the bar on catheter stability to a new level. To achieve permanent wide area isolation of the pulmonary veins (PV), a series of multiple individual focal lesions must be delivered contiguously and with transmurality. Even a single nontransmural lesion can lead to edema that heals and leads to PV reconnection and recurrent AF. In addition, given the complex left atrial anatomy, atrial and ventricular contraction, respiration, and patient movement, the possibility of PV reconnection after AF ablation is not at all surprising. Consider that the recurrence rate after ablation of atrial flutter, which requires deployment of a short sequence of lesions in a linear fashion connecting 2 well-defined anatomic boundaries, can occur in 10% of patients.1 Extend this to the 10-to 12-cm circumference around the typical PV antrum, and the importance of uniform transmural lesions is apparent. Article see p 63It was recognized early that the Achille's heal to AF ablation was early PV reconnection after ablation.2 Although temperature rises and limited power delivery may have limited lesion depth using early 4-mm-tip catheters, the development of irrigated tip catheters has improved our ability to make large enough lesions to achieve transmurality in the atrium. Yet, PV reconnection continued to occur. I recall as a fellow being told by an attending to "ride the wave," as I tried to balance the catheter on the left atrial appendage ridge while the patient snored and fidgeted on the table. Clearly, a catheter sliding back and forth over several centimeters was not the ideal situation for delivering reproducible lesions. Use of steerable sheaths, general anesthesia to minimize patient motion and respiratory motion, and even JET ventilation to remove respiratory excursions completely seemed to enhance the success rate of ablation.3,4 We all use several surrogates of contact force to assure adequacy of lesions during ablation, including catheter stability on fluoroscopy, impedance drop, temperature rise, and electrogram attenuation.Yokoyama et al 5 first emphasized the important relationship between catheter/tissue contact force and lesions size in a preclinical study. There was a direct correlation between catheter/ tissue contact force during ablation and the resulting lesion volume in a canine thigh muscle preparation. This important study led to the early adoption of steerable sheaths to maintain better contact force during AF ablation in many centers. The next step in the evolution of catheter ablation wa...

Simulation and Experiment Analysis of Driveshaft

“…However, high stiffness is also needed to transfer the force and motion precisely. Additionally, the driveshaft in the heart and vascular system will be affected by the heart, respiration, blood, and complex human microchannels [1][2][3], causing deformation in the transmission process and blood vessel damage. Therefore, the mechanical property of the driveshaft is very important for the success of the intervention.…”

“…The existing research shows that the driveshaft deviation results from heart beating and the lack of blood vessel wall support in the heart [1,2]. The accidental movement of the human cardiothoracic activity and external force intervention will cause the driveshaft to deviate from its predetermined position.…”

Feedforward Coordinate Control of a Robotic Cell Injection Catheter

“…Although these systems allow for remote control, a step further for optimizing catheter procedures would be to incorporate automated control where a microcontroller performs parts of the operation using feedback sensors, translating feedback signals into actuator movement. Feedback signals may come from external navigational images, 8 , 17 echocardiograms (ECGs), 18 , 19 electrophysiological readings from electrodes, 20 contact force sensors, 21 intracardiac echocardiography, 22 , 23 and so forth. However, even with real-time feedback signals, time delays may be apparent with complex analyses and control algorithms.…”

New Frontiers in Electrocardiography, Cardiac Arrhythmias, and Arrhythmogenic Disorders

“…Due to the severe complications involved, this was replaced by radiofrequency ablation, which is currently widely used in electrophysiology laboratories. The use of steerable sheaths, contact force sensing (the contact force is positively correlated with the lesion size, steam pops, and thrombus formation), and irrigated tip catheters (larger lesions creation, a lower risk of thrombus and char formation) for ablation has brought about improvements in the field of radiofrequency ablation [12][13][14][15]. The catheters may be visualized using fluoroscopy or three-dimensional electroanatomical mapping techniques, limiting or completely omitting the use of X-rays (zero X-ray ablation) and increasing the precision of ablating the arrhythmogenic substrate.…”