Tricuspid valve regurgitation is a major clinical issue that continues to attract interest from interventional cardiologists and medical device designers due to its rising prevalence and progressive nature. This disease impact is exacerbated among the aging population, considered as high risk of mortality for open-heart surgical procedures. Furthermore, early intervention for tricuspid regurgitation following left-sided heart procedures continues to increase. Thus, percutaneous or transcatheter interventions have emerged as the new frontier for tricuspid valve therapy. Specifically, tricuspid leaflet plication, or edge-to-edge repair, is a valvular procedure to enhance the coaptation of the leaflets and reduce regurgitation. The current landscape of approved transcatheter devices for leaflet coaptation are exclusive to the mitral valve or being investigated for tricuspid treatment. However, most of these transcatheter systems are designed with high procedure specificities, are expensive, and require extensive procedural training. Hence, there is an opportunity to percutaneously plicate the tricuspid leaflets using commonly available right-heart catheter equipment. This study details a novel transcatheter repair procedure that can plicate the tricuspid valve leaflets solely using current market released catheters and/or surgical equipment. Testing and evaluation of this prototype procedure was performed using Visible Heart ® methodologies.

Mitral valve (MV) annular dynamics are critical to the long term efficacy of MV repair. Today’s annuloplasty rings, used to restore MV function, impose significant constraints on the motion profile of the MV annulus. We present a selectively compliant ring that provides sufficient stiffness to stabilize a diseased annulus while allowing physiological annular dynamics. Ring design is informed by a finite element analysis and experimentally evaluated with in-vitro stereophotogrammetry. We compare the ring dynamics to commercially available semi-rigid rings as well as values found in literature for healthy annuli. The results demonstrate that motion of the selectively compliant ring is significantly closer to that of a healthy annulus based on standard metrics that define MV annular movement. Specifically, the metrics for the new ring compare to those in literature as follows: change in orifice area 12.5 ± 3% vs.10 ± 2%; change in anterior-posterior diam. 5.4 ± 0.3% vs. 7 ± 1%; change in inter-commissural diam. 6.6 ± 1.3% vs. 5 ± 1%.

As the prevalence of mitral and tricuspid valvular disease continues to grow with the aging population [1,2], there is a growing critical need to treat high mortality risk patients using minimally invasive and/or non-surgical percutaneous procedures. However, these transcatheter procedures, especially those aimed at repairing or replacing the mitral and tricuspid valves, are mostly still in development and/or early clinical testing. Catheter delivery, prosthesis fixation, and/or demonstrating device efficacy are major challenges currently being addressed [3,4]. Although in situ animal models can assess catheter systems with clinical imaging, direct visualization of tissue-device interactions in real human heart anatomies are desired. In vitro delivery and implantations of valvular prototypes in human heart specimens can be instrumental for accurate device testing and gaining important design insights. Such investigations can be performed on a pulsatile flow apparatus, utilizing perfusion fixed human hearts with mitral and/or tricuspid valves eliciting coaptation and relative function. The employment of endoscopic cameras provides direct visualization and can be coupled with echocardiography, providing novel insights relative to these transcatheter devices in a dynamic environment. However, these investigative approaches require appropriately fixed human heart specimens that will allow for dynamic valve movement. This study discusses the design, construction, and implementation of a novel fixation apparatus to promote the coaptation of the mitral and tricuspid valves in swine and fresh human heart specimen.

Transcatheter replacement therapies for the atrioventricular (AV) valves are considered as the next frontier for the treatment of valvular regurgitation. The AV valves, tricuspid and mitral, are the regulators of blood flow from the atria into the ventricles. During diastole, blood flows through the open tricuspid and mitral valves to fill the right and left ventricles, respectively. During systole, the ventricles contract, closing the AV valves, and forcing the blood to exit through their respective ventricular outflow tracts (VOTs) to the arterial circulations. Although the current gold standard for the treatment of valvular regurgitation is surgical replacement or repair, the field of transcatheter therapies is rapidly expanding as new treatment options for patients; especially for those individuals considered to be at greater risks for surgical complications. Market released bioprosthetic devices for replacing the aortic and pulmonary valves have shown great promise and success. However, the advancement of similar therapies for either the mitral and tricuspid valves remain in the early stages of development. This slower progress is attributed to the high complexities and variabilities of the AV valves, which present challenges for both device design and post-implantation functions.

Aortic aneurysm is a common disorder which is due to weakening of the aortic wall [1]. Aneurysm rupture is a potentially life threatening complication [2]. The stent graft implantation is one of the potential alternatives for treating patients at high risk for an open surgical procedure. The short-term outcome for stent implantation is promising; however, as with any medical procedure, this has potential limitations such as side branch occlusion, device malfunctions, dilatation at the proximal portion and the so called ‘endoleak’. An endoleak is the persistent blood flow into and within the aneurysmal sac after endovascular repair (i.e. the blood leaks around the endograft which is supposed to have sealed off the entry of blood around it and can be classified into 5 categories[3]). Type I (inadequate seal) and III (graft mechanical failure) endoleaks, characterized by direct communication between systemic and aneurysm sac compartments, pose higher risk of aneurysm rupture and are therefore aggressively treated [4]. Despite advances in the treatment of aneurysm, we believe that there is a still great need for a medical device that can improve patient outcomes.

Endovascular aneurysm repair (EVAR) techniques have been widely used for the treatment of abdominal aortic aneurysm (AAA). EVAR is associated with lower postoperative morbidity and mortality than traditional surgical procedure to treat AAA [1]. However, during the patient’s follow-up, postoperative complications may occur and secondary interventions are required [2]. Stent-grafts fixation in the vessel affects the success of endovascular aneurysm repair. Researches indicate that insufficient stent-graft radial force is attributed to post-surgery complications, such as prosthesis migration and endoleak type I [3, 4]. Endoleak type I happens when there is not a complete contact between stent graft rings and vessel wall. A great radial force can prevent full obturation in the landing zone. The distal endograft fixation also has a great influence on proximal endograft migration after EVAR [5]. Therefore the radial force of the stent plays a significant role. Single stent-graft ring comprise a series of expandable Z-shaped structural elements (known as “struts”). Currently, there are series of Z-shaped stent-grafts on the market and the struts number ranges from 5 to 12. This work intends to analyze the influence of stent-graft struts number on the radial force. Finite-element analysis (FEA) and experimental method are used.

Maintaining upright stance is a complex process, it requires appropriate functioning of a postural control system which consists of inputs from somatosensory, vestibular, musculoskeletal, and proprioceptive systems as well as from several brain regions [1–4]. A concussion is defined as a brain injury caused due to unexpected acceleration/deceleration of the head causing temporary alteration of brain function and it is a prevalent source of injury to football athletes [1]. With the altered function of the brain, the ability to maintain postural equilibrium becomes challenging due to the inability of individuals to respond promptly to stressors, thus, making maintenance of postural equilibrium rather difficult for individuals with a concussion. Effects of concussion on postural ability are shown to last up to three days post injury [5]. Postural stability test, therefore, can be performed to make a valid return to play (RTP) decision, pre-mature RTP is shown to have been catastrophic due to its potential to permanently impair previously affected region/functioning [1,5]. Postural sway data (center of pressure, COP) is traditionally analyzed to study the postural control. Therefore, COP can provide critical information regarding individual’s ability to maintain upright stance post injury. A more sensitive concussion assessment tool based on electroencephalogram (EEG) is used to accurately track effects of concussion [6]. However, sophisticated electrode placement requirement inhibits its immediate applicability. In current preliminary research, we attempt to differentiate athletes with a history of concussion (experimental) from healthy (control) using postural data. In order to do so, a concept of empirical mode decomposition (EMD) was adopted. EMD has shown evidence in the literature to infer vital information pertaining to the complex underlying physiological phenomenon [4, 7–8]. In the current research, the resultant COP (COPr) was decomposed into its finite set of band-limited signals termed as intrinsic mode functions (IMFs) [8], a set of linear and nonlinear features were extracted from COPr and its IMfs. Lastly, a test of significance was conducted to infer the potential of postural data for differentiating concussed from healthy athletes.

Bicoronal approach is commonly used to repair intracranial trauma [1,2]. However, this approach requires long operation time and may lead to a long-lasting visible scar. In addition, patients stay in the hospital for several days. Therefore the demand for minimally invasive operation technique is increasing for reduction of facial bone fracture. Yoo et al. reported closed reduction technique using a thread-tapper device [3]. This method uses the tapper as a tool to make a thread of screw tightening a bolt. The method needs small incision. By pulling out the tapper, the depressed bone segment can be easily recovered. Another method is to use a hook. This device can be inserted into a small hole in the skin [4]. The screw is used for reducing multi-fragmented segments of anterior wall of frontal sinus. Two or more small screws are inserted into fragmented segments, and then pulled out simultaneously [5]. These closed reduction surgical devices have advantages of reducing operation time and scars, and quickening recovery. However, they can be only applied if the tapper or screw can be inserted into the depressed bone segments. In this technical brief, we propose a spiral tool and pulling mechanism for closed reduction facial bone fracture. Using prototypes, we present that the suggested surgical tool and mechanism are good alternatives for reduction of facial bone.

Parkinson’s disease (PD) is a degenerative disease with diverse clinical features. At present, there is no definitive test for the diagnosis of PD [1]. Instead, PD is diagnosed using clinical criteria which are based on the presence and presentation of signs such as rest tremor, bradykinesia, rigidity, loss of postural reflexes, shuffling gait and freezing, as well as non-motor symptoms. Various treatments, ranging from physical therapy and medications to invasive treatments, can help relieve some PD symptoms. These treatments need quantitative monitoring and efficacy evaluation methods in order to provide higher quality, patient-centered care. A quantitative assessment of the patients’ clinical symptoms can also provide a timely alert to adverse events [2]. A variety of devices employing sensors with the purpose of monitoring PD patients’ symptoms were developed [3, 4]. Most of these devices are costly and / or complex in operation and maintenance, which limits their practicality in busy hospital / clinic environments and for home use. Moreover, they do not provide appropriate solutions for monitoring more severe cases of PD, where the patient requires a walking aid such as a cane or walker.

Due to the anatomical and physiological similarities to humans that include similar heart size, flow rate, skin, liver enzymes and bone healing, porcine models as a powerful investigational platform have been widely used in research areas such as diabetes, obesity and islet transplantation [1]. The advantages of relative low cost, ease in handling and comparatively short period of breeding time may make swine provide a promising solution to the shortage of human donors and difficulty in isolating purified islets from adult human in future. Porcine cytokines play a significant role in innate immunity, apoptosis, angiogenesis, cell growth and differentiation. They are involved in cellular responses, maintenance of homeostasis, and disease states such as inflammatory disease, cardiovascular disease, and cancer. Thus, the technologies to analyze the expression of cytokines are developed rapidly and are still hot topics. The traditional approach for cytokine detection and quantification is the use of an enzyme-linked immunosorbent assay (ELISA). However, its inability to do multiplex test calls for more robust detection system. Biochip-based assay for the detection of biological agents using giant magnetoresistive (GMR) sensors and magnetic nanoparticles have emerged recently [2, 3]. It is proved that the nanomagnetic biosensor technology has advantages of low cost, high sensitivity, multiplexity, and real-time signal readout. The integration of GMR biosensor and use of weak magnetic fields allow to eventually realize point-of-care and portability. In addition, interferon gamma (IFNγ) is one of the most important porcine cytokines, and is associated with a number of autoinflammatory and autoimmune diseases. In this work, IFNγ is selected as a model target for the detection of porcine cytokine using nanomagnetic GMR biosensor.

Laparoscopic and robotic surgeries of the abdomen require a trocar to facilitate entry and removal of instrumentation. Some of these trocars are 5mm or less, but some trocars for these surgeries are larger, with 8mm to 15mm trocars commonly used. One of the well-known problems seen in minimally invasive surgery to the abdomen is the resulting defect left in the abdominal wall following removal of the trocars. Occasionally, especially after removal of larger trocars, a defect is left that is large enough to allow omentum or segments of small intestine to become entrapped within the resulting space in the abdominal wall. These trocar site hernias can cause pain, but they also may lead to small bowel obstruction and bowel ischemia or even infarction, perforation and death. The likelihood of a trocar site hernia is increased when the minimally invasive procedure requires removal of an organ or a mass. This often requires dilatation of the trocar site opening. 1,2,3 Re-operation to reduce and repair trocar site hernias adds significant cost to the healthcare system. Two separate studies report that incidence of trocar site hernias are in the ranges of 0.65%–2.8% 4 and 1.5%–1.8% 5,6 . Based on a 2016 report published by the American Society for Metabolic and Bariatric Surgery (ASMBS), 196,000 7 bariatric procedures were performed in 2015. Assuming an average incidence rate of 1.7%, and based on the cost analysis provided by a 2008 case study 8 , in bariatric surgery alone, it is estimated that the treatment and hospitalization of such hernias adds an additional $86.2M to healthcare costs. Several methods and devices exist to prevent the occurrence of trocar site hernias. However, closing superficial fascia externally is difficult, especially in obese patients, and often requires extending the skin incision significantly. Most instruments to close the potential hernia site involve introducing a hollow needle with a built-in, grasping device through tissue on one side of the defect and into the abdominal cavity. This puts internal structures at risk for potential injury. One end of suture is introduced with this needle and then using a separate instrument through a different trocar this suture is held while the needle is removed. The needle device is then re-introduced through tissue on the opposite side of the defect, and the suture is handed back to the needle device and pulled out completing a U-stitch to close the potential hernia site. If a surgeon inserts a finger into the abdomen along the trocar site to guide the needle, there is the potential for injury to the surgeon’s finger. Therefore, we set about to design a device to close trocar site defects that would work efficiently, while being safe from injury to the patient or the surgeon, and preferably without the need for a separate instrument through a different trocar to assist.

Mitral Regurgitation (MR) is a malfunction of the mitral valve where the blood flows backward because of improper closure of the valve. The blood flows back through the mitral valve to the left atrium during the contraction of the left ventricle. This condition usually causes shortness of breath, fatigue, lightheadedness, and a rapid heartbeat. It is estimated that 2% of the global population have significant mitral valve disease. In US, more than 200,000 patients are diagnosed with this condition each year [1]. Current treatments include anticoagulation medication, and surgeries to replace or repair the dysfunctional mitral valve. Open heart surgery has been the conventional approach to repair or replace the mitral valve. However, for a large percentage of patients (almost 30%), open heart surgery carries increased risk of mortality and morbidity due to their advanced age and dysfunction of the left ventricle [2]. Recently, less invasive, transcatheter approaches to mitral valve disease have been developed to decrease the surgical risk for these patients. [3]. One of the approaches that has recently shown promising outcomes is the placement of a MitraClip system (Abbott Vascular, Inc., Santa Clara, California) to stop or decrease the undesired leakage. MitraClip is a metal clip coated with fabric that is implanted on the mitral valve leaflets to allow the valve to close more completely. After clip placement, blood flows in an assisted fashion as the mitral valve opens and closes on the either sides of the clip. The whole procedure for placement of the MitraClip in Transcatheter Mitral Valve Repair (TMVR) takes 2 to 3 hours under general anesthesia. A transesophageal echocardiogram is used to observe the blood flow and to trace the placement of the clip. A catheter is guided inside the femoral artery after percutaneous access is established. Then a guide wire is inserted to reach the mitral valve. At this time the MitraClip is threaded into the target position between the leaflets, and then, the guide is removed. Precise placement and orientation must be achieved at this point to best secure the clip with the minimum leakage possible. Since the implantation is being done inside a beating heart, this precise placement is the most challenging part of the surgery. Currently trial and error along with precise measurements are being utilized to find the best position. This work introduces an innovative MitraClip locator device based on the most advanced materials and actuators to assist in the positioning of the MitraClip during implantation; this would potentially facilitate the most challenging and improtant step of the procedure. Currently, doctors are spending most of their surgical time (roughly 90 min) finding the correct orientation for the clip. The proposed self-actuated MitraClip locator device uses active Shape Memory Alloys (SMAs), Nitinol wires, in order to expedite surgical procedures with a higher precision. SMA wires have been used in medical devices safely and effectively [4,5]. Fig. 1 shows the schematic picture of our novel design that includes evenly distributed SMA wires inside a shaft to enable orientations in multiple directions. This design is proposed as a scaled model for preliminary testing. After thorough testing and evaluation on this model a real size prototype will be made for the real application. This work presents a detailed design of our innovative device. This device has been fabricated and tested to show the proof of concept. The main purpose of this work is to show the feasibility of achieving movements in multiple directions using three shape memory alloy wires. As a long term plan, the authors aim to have this mechanism (while its accuracy and safety is assured) attached behind the MitraClip to facilitate controlled, accurate positioning.

Living tissue engineered heart valves (TEHV) may circumvent ongoing problems in pediatric valve replacements, offering optimum hemodynamic performance and the potential for growth, remodeling, and self-repair [1]. Although a myriad of external stimuli are available in current bioreactors (e.g. oscillatory flows, mechanical conditioning, etc.), there remain significant bioengineering challenges in determining and quantifying parameters that lead to optimal ECM development and structure for the long term goal of engineering TEHVs exhibiting tissue architecture functionality equivalent to native tissue. It has become axiomatic that in vitro mechanical conditioning promotes engineered tissue formation (Figure 1), either in organ-level bioreactors or in tissue-level bioreactors with idealized-geometry TE constructs. However, the underlying mechanisms remain largely unknown. Efforts to date have been largely empirical, and a two-pronged approach involving novel theoretical developments and close-looped designed experiments is necessary to reach a better mechanistic understanding of the cause-effect interplay between MSC proliferation and differentiation, newly synthetized ECM, and tissue formation, in response to the controllable conditions such as scaffold design, oxygen tension, nutrient availability, and mechanical environment during incubation. We thus evaluate the influence of exterior flow oscillatory shear stress and dynamic mechanical conditioning on the proliferative and synthetic behavior of MSCs by employing a novel theoretical framework for TE. We employ mixture theory to describe the evolution of the biochemical constituents of the TE construct and their intertwined biochemical reactions, evolving poroelastic models to evaluate the enhancement of nutrient transport occurring with dynamic mechanical deformations, and computational fluid dynamics (CFD) to assess the exterior flow boundary conditions developed in the flex-stretch-flow (FSF) bioreactor [4–6].

Many surgeons have come to view mitral valve (MV) repair as the treatment of choice in patients with mitral regurgitation (MR) [1]. According to recent long-term studies, the recurrence of significant MR after repair may be much higher than previously believed, particularly in patients with (ischemic mitral regurgitation) IMR [2]. We hypothesize that the restoration of homeostatic normal MV leaflet tissue stress in IMR repair techniques ultimately leads to improved repair durability. Therefore, the objective of this study is to develop a novel micro-anatomically accurate 3D finite element (FE) model that incorporates detailed collagen fiber architecture, accurate constitutive models, and micro-anatomically realistic valvular geometry to investigate the functional mitral valve and to aid in the assessment of the mitral valve repairs, especially the linking between the interstitial cellular deformations at the cellular level, the mechanobiological behaviors at the tissue level and the organ level mechanical responses as normal and repaired mitral valves maintaining their homeostatic state.

Mitral valve repair is a highly challenging procedure. Surgeons must modify native valve tissue through a series of tissue resections and approximations. Restoring proper valve function is difficult because the heart is arrested during the procedure, so closed valve shape must be predicted rather than directly observed. It is this prediction, not the act of cutting and suturing, that presents the greater challenge to surgeons as they must rely on analysis of the flaccid valve and past experience. This skill is developed through traditional pedagogy, namely text- and image-based references, followed by a costly and time-consuming apprenticeship model.

Cutting edge computational tools are an important component of the future of tasks such as surgical planning of mitral valve repair and the design and evaluation of prosthetic valves. For example, despite half a century of use, mechanical heart valves still require further research to reduce the non-physiologic nature of the flow field, which is the source of potential medical complications, of which the most serious complication is thrombus formation [1]. In fact, there is still a lack of consensus in the literature about which flow pathologies are the most damaging to blood elements [2, 3]. Much computational work has been performed examining the flow around mechanical heart valve devices [4, 5], but because the emphasis has been on correct valve motion and not fine structure detail, only the largest features have been adequately resolved and the forward flow structures are allowed to dissipate on stretched meshes such that the features may not lead to the correct fine structure state as directionality of blood flow changes during the cardiac cycle.

Numerical models of the heart’s mitral valve are being used to study valve biomechanics, facilitate predictive surgical planning, and are used in the design and development of repair devices. These models have evolved from simple two-dimensional approximations to complex three-dimensional fully coupled fluid structure interaction models. However, to date these models lack direct one-to-one experimental validation. Moreover, as computational solvers vary considerably based on researcher implementation, experimental benchmark data are critically important to ensure model accuracy. To this end, a multi-modality in-vitro pulsatile left heart simulator was used to establish a database of geometric and hemodynamic boundary conditions coupled with resultant valvular and fluid mechanics.

The endovascular treatment of abdominal aortic aneurysm (EVAR) consists of inserting a delivery system through intravascular pathway and deploying one or several stent-grafts at the aneurysm site in order to exclude it. This procedure has proven to have a high success rate for eligible patient population and benefits in terms of reduced blood loss, intraoperative morbidity and length of hospital stay. As the selection criteria for EVAR extend progressively due to enhancements in the devices and delivery systems, clinicians are confronted with cases becoming increasingly difficult and demanding procedures with steep learning curve (aortic dissection, branched and fenestrated stent-graft, and complex anatomy with high tortuosity or short aortic neck). In this context patient-specific Finite Element Modeling (FEM) could provide a predictive tool to support endovascular device assessment and selection as well as intervention planning. Given the lack of dedicated solutions, the aim of this study was to assess the feasibility of simulating the main steps of EVAR procedure, from guidewire insertion to stent-graft deployment.

Heart valve prosthetics replace damaged, malfunctioning valves to improve a patient’s quality of life. Current mechanical valves are durable but suffer from thrombogenicity and flow separation, and can cause blood damage leading to coagulation. While bioprosthetic valves have better haemodynamic function than mechanical valves, the valves suffer from tears due to inflammation and collagen degradation. The absence of living tissue leaves them unable to repair themselves and their antigenicity must be masked. Complications due to thrombosis occur between 1.5% and 3% per year for current mechanical and bioprosthetic valves [1]. Polymeric valves have the potential to exhibit improved haemodynamic performance over mechanical valves without the complications associated with bioprosthetic valves; current issues associated with polymeric valves include calcification, hydrolysis, and durability [2].

Evaluating the risk of endograft migration is important for long-term durability of endovascular aneurysm repair (EVAR) technique. In this paper we apply a step-wise coupled finite element approach to evaluate the risk of endograft migration in representative aorta models subjected to in-vivo hemodynamic displacement forces. Device stability is observed to be a strong function of aortic geometry (tortuosity, proximal fixation) with increased tortuosity or lower proximal fixation leading to greater risk of device migration.