Feasibility Testing of the Bionet Sonar Ultrasound Transcutaneous Energy Transmission (UTET) System for Wireless Power and Communication of a LVAD.

Purpose: To address the clinical need for totally implantable mechanical circulatory support devices, Bionet Sonar is developing a novel Ultrasonic Transcutaneous Energy Transmission (UTET) system that is designed to eliminate external power and/or data communication drivelines.

Methods: UTET systems were designed, fabricated, and pre-clinically tested using a non-clinical HeartWare HVAD in static and dynamic mock flow loop and acute animal models over a range of pump speeds (1800, 2400, 3000 RPM) and tissue analogue thicknesses (5, 10, 15 mm).

Results: The prototypes demonstrated feasibility as evidenced by meeting/exceeding function, operation, and performance metrics with no system failures, including achieving receiver (harvested) power exceeding HVAD power requirements and data communication rates of 10kB/s and pump speed control (> 95% sensitivity and specificity) for all experimental test conditions, and within healthy tissue temperature range with no acute tissue damage.

Impact of Anchor Location on Mitral Neochordae Forces: An In Vitro Study.

Purpose: This study examined changes in force distribution between the neochordae corresponding to different ventricular anchor locations.

Description: Seven porcine mitral valves were mounted in a left heart simulator. Neochordae (expanded polytetrafluoroethylene) originated from either a simulated left ventricular apex, papillary muscle base, or papillary muscle tip location.

Demonstration of proof-of-concept of StrokeShield system for complete closure and occlusion of the left atrial appendage for non-valvular atrial fibrillation therapy.

In the US, the most significant morbidity and mortality associated with non-valvular atrial fibrillation (NVAF) is embolic stroke, with 90% of thrombus originating from the left atrial appendage (LAA). Anticoagulation is the preferred treatment for the prevention of stroke in NVAF patients, but clinical studies have demonstrated high levels of non-compliance and increased risk of bleeding or ineligibility for anticoagulation therapy, especially in the elderly population where the incidence of NVAF is highest. Alternatively, stroke may be preventing using clinically approved surgical and catheter-based devices to exclude or occlude the LAA, but these devices continue to be plagued by peri-device leaks and thrombus formation because of residual volume.

New mitral annular force transducer optimized to distinguish annular segments and multi-plane forces.

Limited knowledge exists about the forces acting on mitral valve annuloplasty repair devices. The aim of this study was to develop a new mitral annular force transducer to measure the forces acting on clinically used mitral valve annuloplasty devices. The design of an X-shaped transducer in the present study was optimized for simultaneous in- and out-of-plane force measurements.

Early feasibility testing and engineering development of a sutureless beating heart connector for left ventricular assist devices.

APK Advanced Medical Technologies (Atlanta, GA) is developing a sutureless beating heart (SBH) left ventricular assist device (LVAD) connector system consisting of anchoring titanium coil, titanium cannula with integrated silicone hemostatic valve, coring and delivery tool, and LVAD locking mechanism to facilitate LVAD inflow surgical procedures. Feasibility testing was completed in human cadavers (n = 4) under simulated normal and hypertensive conditions using saline to observe seal quality in degraded human tissue and assess anatomic fit; acutely in ischemic heart failure bovine model (n = 2) to investigate short-term performance and ease of use; and chronically for 30 days in healthy calves (n = 2) implanted with HeartWare HVAD to evaluate performance and biocompatibility. Complete hemostasis was achieved in human cadavers and animals at LV pressures up to 170 mm Hg.

In-vivo mitral annuloplasty ring transducer: implications for implantation and annular downsizing.

Mitral annuloplasty has been a keystone to the success of mitral valve repair in functional mitral regurgitation. Understanding the complex interplay between annular-ring stresses and left ventricular function has significant implications for patient-ring selection, repair failure, and patient safety. A step towards assessing these challenges is developing a transducer that can be implanted in the exact method as commercially available rings and can quantify multidirectional ring loading.

Contractile mitral annular forces are reduced with ischemic mitral regurgitation.

Objective: Forces acting on mitral annular devices in the setting of ischemic mitral regurgitation are currently unknown. The aim of this study was to quantify the cyclic forces that result from mitral annular contraction in a chronic ischemic mitral regurgitation ovine model and compare them with forces measured previously in healthy animals.

Methods: A novel force transducer was implanted in the mitral annulus of 6 ovine subjects 8 weeks after an inferior left ventricle infarction that produced progressive, severe chronic ischemic mitral regurgitation.

Dynamic assessment of mitral annular force profile in an ovine model.

Background: Limited knowledge exists regarding the forces that act on devices implanted in the mitral annulus. Determining the peak magnitudes, directions, rates, variation throughout the cardiac cycle, and change with left ventricular pressure (LVP) will aid in device development and evaluation.

Methods: Novel transducers with the ability to measure forces in the septal-lateral and transverse directions were implanted in six healthy ovine subjects.

In-vivo transducer to measure dynamic mitral annular forces.

Limited knowledge exists regarding the forces which act on devices implanted to the heart's mitral valve. Developing a transducer to measure the peak force magnitudes, time rates of change, and relationship with left ventricular pressure will aid in device development. A novel force transducer was developed and implanted in the mitral valve annulus of an ovine subject.

Transapical beating heart cardioscopy technique for off-pump visualization of heart valves.

Objective: Endoscopic methods to perform intracardiac procedures are of enormous interest, with the introduction of transcatheter techniques for complex cardiac procedures. In the present study, we demonstrate the use of a novel transapical cardioscopy system to visualize intracardiac structures in a porcine model.

Methods: The cardioscope was designed to mount a miniature CCD camera at its tip and was covered in a blunt convex Plexiglass top that allowed displacement and visualization of the tissue in front of the cardioscope.

In vitro characterization of the mechanisms responsible for functional tricuspid regurgitation.

Background: Functional tricuspid regurgitation (TR) is increasingly recognized as a source of morbidity. Current repair strategies focus on annular remodeling because annular dilatation is common in patients with TR. Although papillary muscle (PM) displacement is recognized in functional mitral regurgitation, its role in TR is less well characterized.

Saddle shape of the mitral annulus reduces systolic strains on the P2 segment of the posterior mitral leaflet.

Background: The three-dimensional saddle shape of the mitral annulus is well characterized in animals and humans, but the impact of annular nonplanarity on valve function or mechanics is poorly understood. In this study, we investigated the impact of the saddle shaped mitral annulus on the mechanics of the P2 segment of the posterior mitral leaflet.

Methods: Eight porcine mitral valves (n = 8) were studied in an in-vitro left heart simulator with an adjustable annulus that could be changed from flat to different degrees of saddle.

Cleft closure and undersizing annuloplasty improve mitral repair in atrioventricular canal defects.

Objective: Reoperation rates to correct left atrioventricular valve regurgitation after primary repair of atrioventricular canal defects remain relatively high. The causes of valvular regurgitation are likely multifactorial, and simple cleft closure is often insufficient to prevent recurrence.

Methods: To elucidate the mechanisms leading to regurgitation, we conducted hemodynamic studies using isolated native mitral valves.

A saddle-shaped annulus reduces systolic strain on the central region of the mitral valve anterior leaflet.

Objectives: Mitral valve repair for degenerative diseases has shown suboptimal results in selected patients. Improved postinterventional mitral valve mechanics are essential to increase repair durability.

Methods: Eight porcine mitral valves were tested in a physiologic left heart simulator under normal hemodynamic conditions.

Efficacy of the edge-to-edge repair in the setting of a dilated ventricle: an in vitro study.

Background: The edge-to-edge repair to correct mitral regurgitation (MR) has shown substandard results in cases of ischemic MR or dilated cardiomyopathy.

Methods: Ten porcine mitral valves were investigated in a left heart simulator (120 mm Hg, 5 L/min). Pathologic conditions of a dilated ventricle were simulated by using an annular model capable of three levels of dilation (normal, 56%, and 120%) and by displacing papillary muscles (PMs) 10 mm in the apical, lateral, and posterior directions.

Mechanics of the mitral valve: in vitro studies.

Improved knowledge of mitral valve (MV) mechanics is essential to understanding normal MV function and design; however, there is limited information about the mechanical properties of the MV during physiologic loading. These studies utilized different techniques to characterize the mechanical properties of the MV. Histological techniques were used to examine collagen, elastin, and cellular distribution on the chordae.

Effects of annular size, transmitral pressure, and mitral flow rate on the edge-to-edge repair: an in vitro study.

Background: Although edge-to-edge repair is an established adjunctive procedure, there is still debate on its long-term durability and efficacy.

Methods: Fifteen porcine mitral valves were studied in a physiologic left heart simulator with a variable size annulus (dilated = 8.22 cm2, normal = 6.

Mitral valve function and chordal force distribution using a flexible annulus model: an in vitro study.

Since variations in annular motion/shape and papillary muscle displacement have been observed in studies of dilated cardiomyopathy and ischemic mitral regurgitation, the objective of this study was to investigate the effects of annular motion/flexibility and papillary muscle displacement on chordal force and mitral valve function. Six human mitral valves were studied in a left heart simulator using a flexible annular model. Mitral flow, trans-mitral pressure and chordae tendineae tension were monitored online in normal and pathophysiologic papillary muscle positions.

Effects of papillary muscle position on chordal force distribution: an in-vitro study.

Background And Aim Of The Study: Mitral insufficiency, a common and morbid pathology, has been related to topological changes in the left ventricle. These changes may affect mitral leaflet coaptation by displacing the tips of the papillary muscles (PMs), subsequently changing the tension distribution on the chordae tendineae. Therefore, further understanding of the effects of PM displacement on chordal force distribution is required.

Effects of a saddle shaped annulus on mitral valve function and chordal force distribution: an in vitro study.

Studies have concluded that the shape of the human mitral valve annulus is a three-dimensional saddle. The objective of this study was to investigate the effects of a saddle shaped annulus on chordal force distribution and mitral valve function. Eleven human mitral valves were studied in a physiological left heart simulator with a variable shaped annulus (flat versus saddle).