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Biomedical subjects

L R Golding

Publications and source records attributed to L R Golding.

At least 37 records · Page 2Linked to original sources
PubMed1982

Clinical results of mechanical support of the failing left ventricle.

Six patients received mechanical support for a failing left ventricle after corrective cardiac operations. Despite intra-aortic balloon pumping and pharmacologic support, intractable failure persisted and cardiopulmonary bypass could not be withdrawn. The left ventricular assist device (LVAD) consists of a nonpulsatile centrifugal pump and two thromboresistant cannulas. Balloon counterpulsation added a pulsatile effect. LVAD support was continued for 72 to 168 hours and five patients were weaned from LVAD support. Two died of persistent low cardiac output within 3 days after pump removal, and a fourth died of multiple organ failure and pneumonia 8 weeks after LVAD removal. Autopsy studies in the first three patients showed myocardial necrosis greater than 50% of the left ventricular mass. Two patients survived after 72 and 74 hours of LVAD support. One patient is fully employed and active 27 months after a cardiac operation; the second is fully active 20 months after operation. Repeat cardiac catheterizations in both have shown all grafts patent and good ventricular function. These two long-term survivors justify the concept of LVAD support and its continued use in selected postoperative patients.

Adult↗
PubMed1980

Initial clinical experience with a new temporary left ventricular assist device.

A new, simple left ventricular assist system has been developed and its use in experimental animals has been evaluated. The system achieves ventricular drainage by a transaortic valve cannula and utilizes a new centrifugal pump; the blood access is unique in requiring only a simple end-to-side synthetic graft anastomosis to the ascending aorta. Adequate pulsatility is obtained by concomitant use of an intraaortic balloon pump. This case report documents our initial clinical experience with this system in a postoperative patient with profound left ventricular failure unresponsive to all usual treatment. There was temporary recovery of left ventricular function upon decannulation after five and a half days of assist pumping. Despite the eventual death of the patient, the system functioned adequately, suggesting that it has good potential for use in a small, selected group of patients.

Assisted Circulation↗
PubMed1980

Chronic nonpulsatile blood flow in an alive, awake animal 34-day survival.

Most acute studies of nonpulsatile blood flow have shown effects on systemic organs. There have been few long-term studies of the effects of nonpulsatile blood flow due to lack of an appropriate experimental model and, consequently, it is unknown whether mammalian physiology can adapt to chronic nonpulsatile blood flow. The following case report documents the effects of chronic nonpulsatile blood flow in an alive, awake animal maintained with fibrillating ventricles for a period of 34 days.

Animals↗
PubMed1979

Posterior midventricular rupture after mitral valve replacement.

Posterior midventricular rupture occurred in 3 patients after insertion of a mitral prosthesis. Iatrogenic surgical trauma was not implicated. There were five clinical factors common to each case: a woman with mitral stenosis; a left ventricle of relatively normal size; the use of intermitent cold cardioplegia; the insertion of a porcine heterograft valve; and transient postoperative hypertension. Rupture in such cases may be caused by hyperdynamic left ventricular contraction against the strut of the prosthesis. Causes of ventricular perforation are discussed.

Bioprosthesis↗
PubMedDate not supplied

Muscle powered circulatory assist device for diastolic counterpulsator.

A diastolic counterpulsator that uses either skeletal muscle or pneumatic actuation was developed. The unit is positioned between the latissimus dorsi and the chest wall, without interference with collateral blood supply, and is connected in series with the descending aorta. The system was able to generate stroke volumes between 52 and 16 ccs against pressures of 60 and 140 mmHg, respectively. Stroke work at 200 msec stimulation averaged 2.8 X 10(6) ergs. Power output at an afterload of 100 mmHg, and at a rate of 60 bpm, was 0.51 W. Back-up pneumatic actuation provided by an intraaortic balloon pump resulted in a 46% increase in the endocardial viability ratio (EVR).

Animals↗
PubMedDate not supplied

New crisscross-shaped port design for universal serial pumps.

The long range goal is the development of a clinically useful, implantable, skeletal muscle powered cardiac assist device (MCAD). To accomplish this goal, two criteria must be met: good anatomic fit, and antithrombogenicity. Because of the relative locations of the latissimus dorsi (LD) muscle and aorta, there are two possible port arrangements: "crisscrossed" (C design), in which the ports are crossed to anastomotic sites, and "prong" shaped (P design), in which no crossover takes place. The purpose of this paper is to determine which of these designs is best from a fluid dynamic perspective, and hence has the best possibility for low thrombogenicity. Flow visualization (FV) techniques were used during two pumping conditions in a mock loop: worst case (MCAD off) and best case (MCAD driven optimally). Results of the MCAD off tests showed that both designs required immediate actuation (for example, an IABP console). However, FV studies under optimal conditions indicated superiority of the C design, most likely due to kinetic energy-induced rotary motion combined with a minimal interport distance. It is concluded that the C design provides ideal flow dynamics, even in valveless pumps, and also has application to valved devices.

Counterpulsation↗
PubMedDate not supplied

Stable blood lubricated hydrodynamic journal bearing with magnetic loading.

The Cleveland Clinic Foundation's Innovative Ventricular Assist System (IVAS) is distinguished by the use of a special hydrodynamic journal bearing to support the rotating assembly of the blood pump. In a permanently implanted blood pump, this bearing's characteristics of long life and high reliability are of paramount importance. In addition, this bearing's inherent self-pumping flow and the axial through flow caused by an imposed end-to-end pressure difference provides good washing, thus guarding against deposition. The basic computer analysis and preliminary testing results of this bearing were previously presented. This article reports the ongoing studies (both analytic and in vitro tests) on this innovative bearing as a component of the IVAS in general, with particular emphasis on its stable operating characteristics and reliability. The absence of vibration attributable to hydrodynamic instabilities related to the thick fluid film are both calculated and demonstrated during testing. A stable operating center of the rotor is shown to be inherent under magnetic side loads and resulting hydrodynamic bearing forces. A low shear as a result of large fluid-film thicknesses has been calculated, and low hemolysis has been shown by in vitro testing. Several unique design features of the bearing are believed to be responsible for this high level of performance.

Heart-Assist Devices↗
PubMedDate not supplied

The analysis, design, and testing of a blood lubricated hydrodynamic journal bearing.

The Cleveland Clinic Foundation's Innovative Ventricular Assist System (IVAS) uses a hydrodynamic journal bearing to support the rotating assembly of the blood pump. Bearing dimensions are chosen so that a stable film of lubricant develops and separates stationary and rotating pump surfaces during operation. This bearing type provides several advantages for a permanently implanted device, including essentially no wear for very long life and very high reliability, as well as a self pumping action that generates circumferential wash flow and thus lowers the risk of bearing associated deposition. However, these advantages are accompanied by design issues not encountered with typical journal bearing, such as low shear stress, bearing ends that are not at atmospheric pressure, and low radial bearing loads. To address these issues, several concepts for a hydrodynamic blood bearing were designed and analyzed using a special computer code to perform parametric studies. This design analysis code was developed to define optimum bearing performance under selected load and speed ranges and within practical tolerances. Results showed the range of dimensions and conditions over which an effective, reliable, blood lubricated journal bearing can be designed. Subsequent bench testing has validated the theoretical conclusions and shown this bearing type to be very robust in a blood pump application.

Biomechanical Phenomena↗