A Probabilistic Approach for Contact Stability and Contact Safety Analysis of Robotic Intracardiac Catheter

The disturbances caused by the blood flow and tissue surface motions are major concerns during the motion planning of a intracardiac robotic catheter. Maintaining a stable and safe contact on the desired ablation point is essential for achieving effective lesions during the ablation procedure. In this paper, a probabilistic formulation of the contact stability and the contact safety for intravascular cardiac catheters under the blood flow and surface motion disturbances is presented. Probabilistic contact stability and contact safety metrics, employing a sample based representation of the blood flow velocity distribution and the heart motion trajectory, are introduced. Finally, the contact stability and safety for a MRI-actuated robotic catheter under main pulmonary artery blood flow disturbances and left ventricle surface motion disturbances are analyzed in simulation as example scenarios.

In-Vivo Microsystems: A Review

In-vivo sensors yield valuable medical information by measuring directly on the living tissue of a patient. These devices can be surface or implant devices. Electrical activity in the body, from organs or muscles can be measured using surface electrodes. For short term internal devices, catheters are used. These include cardiac catheter (in blood vessels) and bladder catheters. Due to the size and shape of the catheters, silicon devices provided an excellent solution for sensors. Since many cardiac catheters are disposable, the high volume has led to lower prices of the silicon sensors. Many catheters use a single sensor, but silicon offers the opportunity to have multi sensors in a single catheter, while maintaining small size. The cardiac catheter is usually inserted for a maximum of 72 h. Some devices may be used for a short-to-medium period to monitor parameters after an operation or injury (1–4 weeks). Increasingly, sensing, and actuating, devices are being applied to longer term implants for monitoring a range of parameters for chronic conditions. Devices for longer term implantation presented additional challenges due to the harshness of the environment and the stricter regulations for biocompatibility and safety. This paper will examine the three main areas of application for in-vivo devices: surface devices and short/medium-term and long-term implants. The issues of biocompatibility and safety will be discussed.

Automatically steering cardiac catheters in vivo with respiratory motion compensation

A robotic system for automatically navigating ultrasound (US) imaging catheters can provide real-time intra-cardiac imaging for diagnosis and treatment while reducing the need for clinicians to perform manual catheter steering. Clinical deployment of such a system requires accurate navigation despite the presence of disturbances including cyclical physiological motions (e.g., respiration). In this work, we report results from in vivo trials of automatic target tracking using our system, which is the first to navigate cardiac catheters with respiratory motion compensation. The effects of respiratory disturbances on the US catheter are modeled and then applied to four-degree-of-freedom steering kinematics with predictive filtering. This enables the system to accurately steer the US catheter and aim the US imager at a target despite respiratory motion disturbance. In vivo animal respiratory motion compensation results demonstrate automatic US catheter steering to image a target ablation catheter with 1.05 mm and 1.33° mean absolute error. Robotic US catheter steering with motion compensation can improve cardiac catheterization techniques while reducing clinician effort and X-ray exposure.

A Deployable Transseptal Brace for Stabilizing Cardiac Catheters

A bracing device for stabilizing cardiac catheters inside the heart was developed to provide surgical-level dexterity to minimally invasive catheter-based procedures for cardiac valve disease. The brace was designed to have a folding structure, which lies flat along a catheter during navigation through vasculature and then unfolds into a rigid bracing configuration after deployment across the interatrial septum. The brace was designed to be easily deployable, provide bracing support for a transseptal catheter, and also be compliant enough to be delivered to the heart via tortuous vasculature. This aims to improve dexterity in catheter-based mitral valve repair and enable other complex surgical procedures to be done with minimally invasive instruments.

Transforming Cardiac Catheters into Treatment Tools

Percutaneous transluminal coronary angioplasty (PTCA) transformed the cardiac catheter from a diagnostic tool into a treatment tool. The technology involved a special catheter fitted with a balloon near its tip that could be blown up to expand a narrowed coronary artery segment. For patients with angina, the procedure was an attractive alternative to coronary bypass surgery. Mayo cardiologists were among the first to adopt angioplasty and to call for controlled clinical trials to compare it to bypass surgery. Initially, cardiologists (who already performed coronary angiography) learned to perform PTCA informally. After attending one or more live demonstration courses, many began to perform angioplasty in their local hospitals. The philosophy in many contexts was “see one, do one.” By the mid-1980s, however, more rigorous training expectations were elaborated. Heart specialists who performed PTCA were described as “interventional cardiologists,” a phrase that acknowledged that this catheter-based treatment had immediate effects.