Chronic aortic root pressure-loading assessment model.

Purpose: Percutaneous placement of transcatheter prosthetic aortic valves without cardiopulmonary bypass (CPB) continues to gain clinical acceptance. However, information on pressure-loading characteristics of the aortic root/annular areas is limited. For this reason, we designed a preclinical model, implanting an aortic root load transducer with a power source/telemetry system for chronic, conscious, loading data acquisition.

Surgical approaches to vascular access for large-caliber devices in preclinical research models.

Percutaneous vascular access options in preclinical models are often smaller than the relevant structures in humans or undersized for early-prototype research devices. Here we describe the surgical approaches and results for surgical vascular access sites in preclinical swine and sheep models. Fourteen adult miniature swine underwent successful 18-French vascular access by means of thoracotomy to the brachiocephalic artery.

Phasic coronary blood flow patterns in dogs vs. pigs: an acute ischemic heart study.

Background: Canine and porcine hearts have been widely used to investigate diagnoses, interventions, and surgical therapies for ischemic heart disease. Dogs and pigs are known to vary with regard to the anatomic distribution of their coronary arteries. However, the mechanisms of these differences and the differing phasic coronary blood flow patterns between the two species are not well characterized.

Acute reduction of functional mitral regurgitation in canine model using an epicardial device.

Purpose: This study evaluated the short-term feasibility of a novel epicardial device that treats functional mitral regurgitation by simultaneously changing the mitral and the left ventricular geometry.

Description: We implanted a prototype device that consists of 2 tissue anchors, a deflector, and a flexible tightening chord in 7 mongrel dogs with heart failure and functional mitral regurgitation induced by rapid ventricular pacing. Hemodynamic and echocardiographic data were obtained before and after device implantation.

Beating heart cardioscopy: a platform for real-time, intracardiac imaging.

Purpose: The purpose of this study was to develop a method for real-time, fiberoptic, intracardiac imaging to serve as a platform for closed-chest, intracardiac surgery on the beating heart.

Description: Fiberoptic cardioscopy of the left and right heart was conducted in a porcine model. A cardiopulmonary bypass circuit maintained systemic organ perfusion and a separate circuit replaced intracardiac blood with oxygenated, modified Krebs-Henseleit perfusate.

Hemodynamic and metabolic changes during exercise in calves with total artificial hearts of different sizes yet similar output.

To evaluate the effects of downsizing of the total artificial heart (TAH), we compared the anaerobic threshold (AT) values in calves with two different types of TAH (Cleveland Clinic-Nimbus TAH and the downsized MagScrew TAH). Exercise studies were performed using a treadmill in 12 calves. During the exercise, parameters to obtain the AT were measured.

Cadaver fitting study of the DexAide right ventricular assist device.

The DexAide right ventricular assist device (RVAD) has been developed to provide an implantable RVAD option to surgeons. The aim of this study was to determine the optimal cannula design and optimal implantation location of the DexAide RVAD in preparation for its clinical use. Separately, a HeartMate XVE left ventricular assist device (LVAD) and CorAide LVAD models were implanted into the preperitoneal and right thoracic space, and the anatomical fit of the DexAide RVAD was evaluated in five preserved human cadavers.

A novel technique for functional mitral regurgitation therapy: mitral annular remodeling.

Background: Functional mitral regurgitation (AIR) plays a pivotal role in the pathophysiology of congestive heart failure, a major cause of cardiac morbidity and mortality. We have developed a mitral annular remodeling procedure through injection of a nonabsorbable substance into the peri-annular tissue of the posterior mitral annulus to reduce the mitral annular dimension in the septal-lateral axis. The purpose of this study is to describe a novel procedure for treatment of functional AIR and report its effects on the geometry of the mitral annulus and degree of AIR.

Cleveland Clinic PediPump lamb cadaver fitting studies.

We are developing the PediPump, a magnetically suspended, mixed-flow pump, as an implantable pediatric ventricular assist device (VAD). Lamb cadaver fitting studies were performed to determine the optimal pump location and optimal design of the inflow and outflow conduits for chronic in vivo studies. A prototype of the PediPump right and left ventricular assist devices (RVAD and LVAD, respectively) were implanted via a sternotomy or left thoracotomy in four lamb cadavers (3.

Acute in vivo evaluation of a new stentless mitral valve.

Objectives: We have developed a stentless pericardial mitral valve prosthesis in 2 configurations; the purposes of this acute study in sheep were to assess (1) valve design and implant technique; (2) valve performance; and (3) acute effects on postimplant left ventricular function.

Methods: A stentless bovine pericardial bileaflet valve was developed with the intent to preserve annular-papillary muscle continuity. This valve, in 2 configurations-with (n = 5) and without (n = 5) flap chordae-was implanted in 10 sheep (mean weight 73 +/- 9 kg).

Impact of left atrial appendage exclusion on left atrial function.

Objectives: We sought to investigate the short-term and midterm effects of left atrial appendage exclusion on left atrial function. Left atrial appendage exclusion is considered a possible therapeutic option for stroke prevention in patients with atrial fibrillation. Favorable outcomes have encouraged widespread use of left atrial appendage exclusion for cardiac surgical patients-even for patients in sinus rhythm who have stroke risk factors; however, the chronic effects on left atrial function of left atrial appendage exclusion are unclear.

Progress in the development of the DexAide right ventricular assist device.

The DexAide right ventricular assist device (RVAD) is an implantable centrifugal pump modified from the CorAide left ventricular assist device. As previously published, in vitro performance testing of the DexAide RVAD has met design criteria, and the nominal operating condition of 4 l/min and 20 mm Hg pressure rise was achieved at 2,000 rpm, with a power consumption of 1.9 watts.

The PediPump: development status of a new pediatric ventricular assist device: update II.

The PediPump is a new ventricular assist device with a hydraulic output range designed for children from newborn infants to adolescents. The design is based on a mixed-flow rotary pump; the rotating assembly consists of a front impeller, front and rear radial magnetic bearings, and a central motor magnet. Two different implantable pumps were designed initially: an intravascular pump measuring 7 x 75 mm and an extravascular pump measuring 14 x 85 mm.

Replacement of the left-side valves of an implanted total artificial heart.

The MagScrew total artificial heart (TAH) is under development. Despite its anticipated durability and reliability, the possibility of a bioprosthetic valve malfunction exists. As a result, the potential for valve replacement surgery, instead of device replacement, would be desirable after a TAH implant.

Evaluation of a novel device for left atrial appendage exclusion: the second-generation atrial exclusion device.

Background: The left atrial appendage is a frequent source of thromboemboli in patients with atrial fibrillation. Exclusion of the left atrial appendage may reduce the risk of stroke in patients with atrial fibrillation. The atrial exclusion device, previously developed to perform left atrial appendage exclusion on a beating heart, was modified to accommodate different anatomic patterns of the human left atrial appendage and to ensure uniform pressure and occlusion.

Ventral cardiac denervation increased right coronary arterial blood flow.

Background: Cardiac denervation accompanied with coronary artery bypass surgery has been widely performed for the treatment of vasospastic angina associated with atherosclerotic coronary artery disease. However, the effect of cardiac denervation on phasic coronary blood flow patterns of the left anterior descending coronary artery (LAD), left circumflex coronary artery (LCX) and right coronary artery (RCA) remains unknown. This study aimed to investigate the effect of cardiac denervation on phasic coronary blood flow patterns of the LAD, LCX and RCA.

Development of patient-specific three-dimensional pediatric cardiac models.

The availability of algorithms to create three-dimensional (3D) models from medical images has made it possible to render and build patient-specific reconstructions of individual body parts. In the present study, this technology was used to create 3D models of pediatric hearts for use in medical device development. Digital models were created using CT datasets of pediatric hearts and commercially available 3D image processing software.

Transmural distribution of myocardial blood perfusion and phasic coronary blood flow pattern in a canine model of acute ischemia.

Background: Although several investigators have analyzed coronary artery blood flow under various conditions, almost all these studies have measured only some branches of the left anterior descending (LAD), left circumflex (LCX), or right coronary (RCA) artery.

Methods: In a canine model of acute ischemia (n = 5), we simultaneously assessed (a) regional myocardial blood perfusion using microspheres and (b) phasic coronary blood flow patterns as measured by three epicardial flow probes placed around the LAD, LCX, and RCA.

Results: The results from this study indicated that the LAD supplies blood to the epicardial (r = 0.

Initial in vivo evaluation of the DexAide right ventricular assist device.

Despite the increasing use of left ventricular assist devices for patients with end-stage congestive heart failure, no implantable, centrifugal right ventricular assist devices (RVADs) are available for those patients with significant right ventricular failure. The DexAide RVAD was developed to provide an implantable RVAD option to surgeons. The aim of this study was to evaluate pump performance in an acute in vivo model.

Development of a small implantable right ventricular assist device.

The purpose of this program is to design, develop, and clinically evaluate a new, implantable right ventricular assist device (RVAD) that can be used as a component of an implantable biventricular assist device for patients with severe biventricular heart failure. The initial phase of this program resulted in a prototype RVAD, named DexAide, a modified version of the CorAide left ventricular assist device. In vitro testing was performed in a stand-alone circuit and in a true RVAD mode to evaluate pump performance.

In vitro performance of the novel coronary sinus AutoRetroPerfusion Cannula.

Myocardial salvage through coronary sinus intervention has been documented. The AutoRetroPerfusion Cannula is a novel device that is able to perfuse the coronary bed retrogradely through the coronary sinus with arterial blood generated from a peripheral artery with no need for a pump. The cannula consists of a distal end that, once secured in the coronary sinus, opens an umbrella-like membrane to create pressure in the coronary sinus, and at the same time has small channels directed backwards to the right atrium to provide pressure relief.

Performance and reliability of the CPB/ECMO Initiative Forward Lines Casualty Management System.

The Cleveland Clinic Foundation CPB/ECMO Initiative Forward Casualty Management System is an economical, compact, transportable, disposable system designed to permit a rapid expansion of trauma management services requiring cardiopulmonary bypass (CPB) or extracorporeal membrane oxygenation (ECMO) pulmonary support. The system, composed of a rotary blood pump, a pump motor driver, and an electronic control console as the blood pumping subsystem, also includes commonly used compatible commercial oxygenators, venous reservoirs, and cannulae. In vitro durability testing accumulated over 100 hours without failure.

MagScrew TAH: an update.

The MagScrew Total Artificial Heart (TAH) system is the result of a close collaboration among the Cleveland Clinic Foundation, Foster Miller Technologies, Wilson Greatbatch Ltd, and Whalen Biomedical Inc. The system components are the thoracic blood pumping unit with attached compliance chamber and refill port, implantable electronic control unit, implantable battery pack, transcutaneous energy transmission system, external battery pack, and a telemetry system for communication with the electronic control unit. System in vitro tests are underway for system characterization and durability demonstration, whereas in vivo tests were conducted to evaluate system performance and biocompatibility under physiologic conditions.

The pedipump: development status of a new pediatric ventricular assist device.

The PediPump is a new rotary dynamic ventricular assist device designed specifically for pediatric applications. Although it is capable of providing support for adults, the small size of the PediPump makes it suitable for newborn circulatory support while retaining excellent hemodynamics. Current and future development plans include: (1) determination of the basic engineering requirements for hardware and control logic, including design analysis for system sizing, evaluation of control concepts and bench testing of prototypes; (2) performance of preclinical anatomical fitting studies using computed tomography-based three-dimensional modeling; and, (3) evaluation with animal studies to provide characterization and reliability testing of the device.

Experimental study of new diagnostic system for coronary artery disease using coronary transit index.

Objectives: Noninvasive cardiac imaging techniques have had an increasing role in the diagnosis of coronary artery disease. However, these techniques are not widely available as a tool in the office setting. The purpose of this study was to provide an accurate assessment of coronary artery disease for screening purposes using Coronary Transit Index (CTI) assessment with small, high-resolution gamma cameras.