Importance of Preserved Tricuspid Valve Function for Effective Soft Robotic Augmentation of the Right Ventricle in Cases of Elevated Pulmonary Artery Pressure.

PURPOSE: In clinical practice, many patients with right heart failure (RHF) have elevated pulmonary artery pressures and increased afterload on the right ventricle (RV). In this study, we evaluated the feasibility of RV augmentation using a soft robotic right ventricular assist device (SRVAD), in cases of increased RV afterload. METHODS: In nine Yorkshire swine of 65-80 kg, a pulmonary artery band was placed to cause RHF and maintained in place to simulate an ongoing elevated afterload on the RV. The SRVAD was actuated in synchrony with the ventricle to augment native RV output for up to one hour. Hemodynamic parameters during SRVAD actuation were compared to baseline and RHF levels. RESULTS: Median RV cardiac index (CI) was 1.43 (IQR, 1.37-1.80) L/min/m2 and 1.26 (IQR 1.05-1.57) L/min/m2 at first and second baseline. Upon PA banding RV CI fell to a median of 0.79 (IQR 0.63-1.04) L/min/m2. Device actuation improved RV CI to a median of 0.87 (IQR 0.78-1.01), 0.85 (IQR 0.64-1.59) and 1.11 (IQR 0.67-1.48) L/min/m2 at 5 min (p = 0.114), 30 min (p = 0.013) and 60 (p = 0.033) minutes respectively. Statistical GEE analysis showed that lower grade of tricuspid regurgitation at time of RHF (p = 0.046), a lower diastolic pressure at RHF (p = 0.019) and lower mean arterial pressure at RHF (p = 0.024) were significantly associated with higher SRVAD effectiveness. CONCLUSIONS: Short-term augmentation of RV function using SRVAD is feasible even in cases of elevated RV afterload. Moderate or severe tricuspid regurgitation were associated with reduced device effectiveness.

In Vivo Molding of Airway Stents.

Like ready-to-wear clothing, medical devices come in a fixed set of sizes. While this may accommodate a large fraction of the patient population, others must either experience suboptimal results due to poor sizing or must do without the device. Although techniques have been proposed to fabricate patient-specific devices in advance of a procedure, this process is expensive and time consuming. An alternative solution that provides every patient with a tailored fit is to create devices that can be customized to the patient's anatomy as they are delivered. This paper reports an in vivo molding process in which a soft flexible photocurable stent is delivered into the trachea or bronchi over a UV-transparent balloon. The balloon is expanded such that the stent conforms to the varying cross-sectional shape of the airways. UV light is then delivered through the balloon curing the stent into its expanded conformal shape. The potential of this method is demonstrated using phantom, ex vivo and in vivo experiments. This approach can produce stents providing equivalent airway support to those made from standard materials while providing a customized fit.

Dynamic Augmentation of Left Ventricle and Mitral Valve Function With an Implantable Soft Robotic Device.

Left ventricular failure is strongly associated with secondary mitral valve regurgitation. Implantable soft robotic devices are an emerging technology that enables augmentation of a native function of a target tissue. We demonstrate the ability of a novel soft robotic ventricular assist device to dynamically augment left ventricular contraction, provide native pulsatile flow, simultaneously reshape the mitral valve apparatus, and eliminate the associated regurgitation in an Short-term large animal model of acute left ventricular systolic dysfunction.

Quantification of Avoidable Radiation Exposure in Interventional Fluoroscopy With Eye Tracking Technology.

OBJECTIVES: Reducing avoidable radiation exposure during medical procedures is a top priority. The purpose of this study was to quantify, for the first time, the percentage of avoidable radiation during fluoroscopically guided cardiovascular interventions using eye tracking technologies. MATERIALS AND METHODS: Mobile eye tracking glasses were used to measure precisely when the operators looked at a fluoroscopy screen during the interventions. A novel machine learning algorithm and image processing techniques were used to automatically analyze the data and compute the percentage of avoidable radiation. Based on this percentage, the amount of potentially avoidable radiation dose was computed. RESULTS: This study included 30 cardiovascular interventions performed by 5 different operators. A significant percentage of the administered radiation (mean [SD], 43.5% [12.6%]) was avoidable (t29 = 18.86, P < 0.00001); that is, the operators were not looking at the fluoroscopy screen while the x-ray was on. On average, this corresponded to avoidable amounts of air kerma (mean [SD], 229 [66] mGy) and dose area product (mean [SD], 32,781 [9420] mGycm), or more than 11 minutes of avoidable x-ray usage, per procedure. CONCLUSIONS: A significant amount of the administered radiation during cardiovascular interventions is in fact avoidable.

In vivo tissue regeneration with robotic implants.

Robots that reside inside the body to restore or enhance biological function have long been a staple of science fiction. Creating such robotic implants poses challenges both in signaling between the implant and the biological host, as well as in implant design. To investigate these challenges, we created a robotic implant to perform in vivo tissue regeneration via mechanostimulation. The robot is designed to induce lengthening of tubular organs, such as the esophagus and intestines, by computer-controlled application of traction forces. Esophageal testing in swine demonstrates that the applied forces can induce cell proliferation and lengthening of the organ without a reduction in diameter, while the animal is awake, mobile, and able to eat normally. Such robots can serve as research tools for studying mechanotransduction-based signaling and can also be used clinically for conditions such as long-gap esophageal atresia and short bowel syndrome.

Soft robotic ventricular assist device with septal bracing for therapy of heart failure.

Previous soft robotic ventricular assist devices have generally targeted biventricular heart failure and have not engaged the interventricular septum that plays a critical role in blood ejection from the ventricle. We propose implantable soft robotic devices to augment cardiac function in isolated left or right heart failure by applying rhythmic loading to either ventricle. Our devices anchor to the interventricular septum and apply forces to the free wall of the ventricle to cause approximation of the septum and free wall in systole and assist with recoil in diastole. Physiological sensing of the native hemodynamics enables organ-in-the-loop control of these robotic implants for fully autonomous augmentation of heart function. The devices are implanted on the beating heart under echocardiography guidance. We demonstrate the concept on both the right and the left ventricles through in vivo studies in a porcine model. Different heart failure models were used to demonstrate device function across a spectrum of hemodynamic conditions associated with right and left heart failure. These acute in vivo studies demonstrate recovery of blood flow and pressure from the baseline heart failure conditions. Significant reductions in diastolic ventricle pressure were also observed, demonstrating improved filling of the ventricles during diastole, which enables sustainable cardiac output.