Direct minimally invasive intraoperative electrophysiological mapping of the heart.

INTRODUCTION: Cardiac electrophysiology aims to describe and treat the electrical activity of the heart. Although an epicardial approach is valuable in many surgical treatments such as coronary artery bypass grafting, maze ablation, and cell transplantation, very few techniques suited for minimally invasive surgery are available for measurement of epicardial electrophysiology. MATERIAL AND METHODS: We developed a novel endoscopically-deployable expanding electrode array that can be applied for minimally invasive surgery. Our device consists of a flexible electrode array attached to arms which open and close the electrode sheet. Furthermore, we also developed a computer program to overlay an epicardial electrophysiological map on an endoscopic image. We performed both laboratory and in vivo experiments to examine the feasibility in clinical situations. RESULTS: Evaluation experiments demonstrated that our novel mapping process that assumes spherical deformation of the electrode array enables us to overlay each electrode position with an accuracy of < 1 mm. Results of animal experiments using large animals (one dog and two pigs) demonstrated that our system enables construction of epicardial electrophysiological maps. CONCLUSION: A novel endoscopically deployable expanding electrode array was developed. Evaluation experiments demonstrated that our device can be manipulated in simulated minimally invasive surgery, and enables construction of epicardial electrophysiological maps.

Novel C-arm-based planning robotic spinal surgery in a cadaver model using quantitative accuracy assessment methodology.

BACKGROUND: This preclinical study emulating the clinical environment quantitatively analysed the accuracy of pedicle screw insertion using a navigated robotic system. METHODS: Pedicle screws were placed from T7 to L5 in the whole-body form of a cadaver. After the insertion of multiple artificial markers into each vertebra, errors between the planned insertion path and the inserted screw were quantified using the Gertzbein-Robbins system (GRS) and offset calculation. RESULTS: A total of 22 screws were placed. Almost all (95.45% [21/22]) were classified as GRS A or B, while one (4.55%) was GRS C. The mean and standard deviations of entry, tip, and angular offset were 1.78 ± 0.94 mm, 2.30 ± 1.01 mm, and 2.64 ± 1.05°, respectively. CONCLUSIONS: This study demonstrated that pedicle screw insertion using a navigated robotic system had high accuracy and safety. A future clinical study is necessary to validate our findings.

Novel C-arm based planning spine surgery robot proved in a porcine model and quantitative accuracy assessment methodology.

BACKGROUND: We assessed pedicle screw accuracy utilizing a novel navigation-based spine surgery robotic system by comparing planned pathways with placed pathways in a porcine model. METHODS: We placed three mini screws per vertebra for accuracy evaluation and used a reference frame for registration in four pigs (46 screws in 23 vertebrae). We planned screw paths and performed screw insertion under robot guidance. Using C-arm and CT images, we evaluated accuracy by comparing the 3D distance of the placed screw head/tip from the planned screw head/tip and 3D angular offset. RESULTS: Mean registration deviation between the preoperative 3D space (C-arm) and postoperative CT scans was 0.475 ± 0.119 mm. The average offset from preoperative plan to final placement was 4.8 ± 2.0 mm from the head (tail), 5.3 ± 2.3 mm from the tip and 3.9 ± 2.4 degrees of angulation. CONCLUSIONS: Our spine surgery robot showed good accuracy in executing an intended planned trajectory and screw path. This faster and more accurate robotic system will be applied in future studies, first in cadavers and subsequently in the clinical field.

Validation of a CT-guided intervention robot for biopsy and radiofrequency ablation: experimental study with an abdominal phantom.

PURPOSE: We aimed to evaluate the accuracy of a needle-placement robot for biopsy and radiofrequency ablation on an abdominal phantom. METHODS: A master-slave robotic system has been developed that includes a needle-path planning system and a needle-inserting robot arm with computed tomography (CT) and CT fluoroscopy guidance. For evaluation of its accuracy in needle placement, a commercially available abdominal phantom (Model 057A; CIRS Inc.) was used. The liver part of the phantom contains multiple spherical simulated tumors of three different size spheres. Various needle insertion trials were performed in the transverse plane and caudocranial plane two nodule sizes (10 mm and 20 mm in diameter) to test the reliability of this robot. To assess accuracy, a CT scan was performed after each trial with the needle in situ. RESULTS: The overall error was 2 mm (0-2.6 mm), which was calculated as the distance from the planned trajectory before insertion to the actual needle trajectory after insertion. The standard deviations of the insertions on two nodules (10 mm and 20 mm in diameter) were 0.5 mm and 0.2 mm, respectively. CONCLUSION: The CT-compatible needle placement robot for biopsy and radiofrequency ablation shows relatively acceptable accuracy and could be used for radiofrequency ablation of nodules ≥10 mm under CT fluoroscopy guidance.

Simultaneous evaluation of wall motion and blood perfusion of a beating heart using stereoscopic fluorescence camera system.

In this study, we aimed to develop a stereoscopic fluorescence camera system for simultaneous evaluation of wall motion and tissue perfusion using indocyanine green (ICG) fluorescence imaging. The system consists of two high-speed stereo cameras, an excitation lamp, and a computer for image processing. Evaluation experiments demonstrated that the stereoscopic fluorescence camera system successfully performed the simultaneous measurement of wall motion and tissue perfusion based on ICG fluorescence imaging. Our system can be applied to intraoperative evaluation of cardiac status, leading to an improvement in surgical outcomes.

A robotic assistant for trans-oral surgery: the robotic endo-laryngeal flexible (Robo-ELF) scope.

This paper describes the continued development of the Robotic EndoLaryngeal (Robo-ELF) Scope System, a simple clinically usable robot for manipulating flexible endoscopes, particularly in laryngeal surgery. The system includes a robot with three active and two passive degrees of freedom, a five degree of freedom passive positioning arm, a malleable scope shaft support, and a custom joystick controller. The Robo-ELF Scope allows a surgeon to control a flexible endoscope with only one hand and also to release the controls and perform bimanual surgery if desired. We have evaluated the Robo-ELF Scope system in both phantom and cadaver studies and found it superior to hand manipulation of flexible endoscopes and conventional rigid endoscopes.

High-sensitive fluorescence endoscope using electrocardiograph-synchronized multiple exposure.

PURPOSE: Fluorescence-based measurement of cardiac disease, using autofluorescent substances that already exist in the heart, has not been used for endoscopic surgery because the endoscopic lenses cannot transmit sufficient light. A highly sensitive fluorescence endoscope using an electrocardiograph (ECG)-synchronized multiple exposure (ESME) approach was developed that provides a bright fluorescent image. METHODS: A system was developed consisting of an endoscope, an excitation light, an ECG amplifier, a trigger and delay unit, and a computer. This system is based on periodic motion of the heart. Since the shape of the heart can be photographed by ECG triggering in a similar manner, a bright image can be synthesized by accumulating multiple trigger-captured images. Laboratory and in vivo experiments were performed to confirm the effectiveness of ESME. RESULTS: The experimental results revealed that the trigger unit generated the synchronization signals required to produce high-quality images of the heart depending on heart rate. The difference among trigger-captured images from the actual organ, which affects the quality of ESME images, was estimated at 0.65 mm from the calculated displacement of a marker on the heart. The results also revealed that a bright fluorescent image can be captured by ESME. CONCLUSION: A highly sensitive fluorescence endoscope using ESME was developed and successfully tested. The experimental results indicated that the method enabled high-quality image acquisition in a very low illumination environment. This system is effective for the observation of faint fluorescence in the heart and is useful for the intraoperative examination of the heart status.

Image-based electrode array tracking for epicardial electrophysiological mapping in minimally invasive arrhythmia surgery.

PURPOSE: Electrophysiological mapping is effective in realizing a precise minimally invasive arrhythmia surgery. Recently, an epicardial electrophysiological mapping system for minimally invasive arrhythmia surgery was reported. The system requires a small electrode array, a tracking system and a global mapping algorithm. The optical tracking system employed in the research requires line of sight and complicated configuration. This paper proposes a new tracking method for locating an electrode array. METHODS: We developed a small electrode array and optical markers. Center points of respective optical markers and the electrode array are tracked via an endoscopic stream and calculated in image space. The orientation of the electrode array is calculated using the dot product between the vector joining two center points of two upper optical markers and the vector joining two end points of the longest edge of the electrode array. RESULTS: Mean tracking errors of position and orientation of the electrode array were 0.51 mm and 0.64°, respectively. And the processing time was constant at 46 ms per frame. Our method could successfully track the electrode array on the epicardium during in vivo experiment and a global epicardial electrophysiological map was reconstructed from separately measured epicardial electrograms by the small electrode array. CONCLUSIONS: An image-based tracking method for locating an electrode array was proposed. Tracking accuracy, processing time and applicability to surgical environment of our method proved to be acceptable. Consequently, our method enables the electrode array tracking system to be simplified with no separate tracking system.