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Results 501 - 550 of 939
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Chaus N I - - 1997
The electroimpedance indicators' dilution (EIID) technique was used to study the possibility of a simultaneous separate assessment of the biological heart and LVAD performance in the position of LVB. The experimental part of the research was performed on 5 dogs; an artificial ventricle of the pulsing type (USA) with cusps ...
Ohara Y - - 1997
The hemolytic effect of the secondary vane system, the antithrombogenic structure incorporated into the back side of the impeller of the C1E3 Gyro pump, was investigated. Impellers with 0, 2, 3, and 4 secondary vanes and an additional impeller with 2 secondary channels were fabricated and incorporated into the C1E3 ...
Sueshiro M - - 1997
Working toward a completely implantable total artificial heart, we have designed an eccentric roller type total artificial heart. The actuator of this artificial heart is a drum type eccentric roller that squeezes the blood chambers. The blood chambers are made of silicone rubber and are torus in shape. The shape ...
Nishida H - - 1997
The Terumo Capiox centrifugal pump system possesses an automatic priming function in which the motor repeatedly stops and runs intermittently to eliminate air bubbles in the circuit through the micropores of the hollow-fiber membrane oxygenator. By modifying this mechanism, we have developed a pulsatile flow mode. In this mode, maximum ...
Yamada T - - 1997
We have been developing a new type of centrifugal pump for long-term use. The magnetically suspended centrifugal pump (MSCP) contains no shaft and seal so that long life expectancy is predicted. Paracorporeal left ventricular (LV) assist circulation between the left atrium and the descending aorta was instituted using sheep. The ...
Qian K X - - 1997
A permanent impeller heart that could work for years was once an idea. However, now this idea is turning into reality through the use of the magnetically suspended motor. Recently, with our implantable pulsatile impeller pump, 3 left ventricular assisted calves survived for about 2 months (62, 54, and 46 ...
Hare J M - - 1997
BACKGROUND: In patients with left ventricular (LV) dysfunction, inhaled nitric oxide (NO) decreases pulmonary vascular resistance (PVR) but causes a potentially clinically significant increase in left atrial pressure (LAP). This has led to the suggestion that inhaled NO may reach the coronary circulation and have a negative inotropic effect. This ...
Pedersen T H - - 1997
BACKGROUND: We studied whether negative inlet pressure created by a centrifugal pump during extracorporeal membrane oxygenation damages blood. METHODS: Fresh, whole human blood and primer were circulated through a test circuit, applying an inlet pressure of 0, -50, or -100 mm Hg. Thereafter, hemolysis and kidney function were compared between ...
Goldstein D J - - 1997
Right sided circulatory failure (RSCF), a common complication after left ventricular assist device (LVAD) implantation, results in decreased systemic output due to diminished blood flow across the pulmonary vasculature. The authors hypothesized that creation of a venoarterial shunt (VAS) would decompress the right-sided circulation and improve systemic pressure and perfusion ...
Mihaylov D - - 1997
The pulsatile catheter (PUCA) pump is an intraventricular blood pump that can be introduced into the left ventricular cavity through a superficial artery (transarterially) or directly through the thoracic aorta during open chest conditions. When positioned, the pump aspirates blood from the left ventricle and transports it into the ascending ...
Palladino J L - - 1997
Myocardial contractile properties form the cornerstone of the heart's ability to pump blood. Efforts have been made to characterize these properties via classic elasticity theory concepts, which can lead to spurious results, as demonstrated by experiments measuring intramyocardial pressure. Two ways out of these difficulties are identified. One is to ...
Lee-Sensiba K - - 1997
A new disposable insert for the arterial roller pump, the Better-Header, provides safety and functionality beyond what standard tubing provides. It automatically limits pump outlet pressure to a level determined by the user and provides a self-contained, simple means to set pump occlusion. The Better-Header consists of a Starling-like pressure ...
Nanas S N - - 1997
During the last decades a number of left ventricular assist devices has been used especially for patients resistant to pharmacologic treatment and to intraaortic balloon pump (IABP) support for left ventricular failure. A high stroke volume para-aortic counterpulsation device (PACD) has been developed utilizing the principle of the diastolic counterpulsation ...
O'Dwyer C - - 1997
BACKGROUND: Hypotension and vasopressors during cardiopulmonary bypass may contribute to splanchnic ischemia. The effect of restoring aortic pressure on visceral organ, brain, and femoral muscle perfusion during cardiopulmonary bypass by increasing pump flow or infusing phenylephrine was examined. METHODS: Twelve anesthetized swine were stabilized on normothermic cardiopulmonary bypass. After baseline ...
Biglioli P - - 1997
Fifty-five patients with descending thoracic aortic aneurysms were operated upon between October 1987 and October 1994. All patients were supported by a centrifugal pump during operation. The mean(s.d.) duration of cross-clamping was 39(13) min. In order to evaluate the efficacy of the centrifugal pump, haemodynamic and metabolic measurements were made ...
Jahr J - - 1997
The present study analyses the peripheral circulatory effects of pump perfusion on a sympathectomized cat skeletal muscle in terms of effects on segmental vascular resistances (large-bore arterial vessels, arterioles and veins), hydrostatic capillary pressure, capillary filtration coefficient, transcapillary filtration and autoregulation of blood flow. The effect of prostacyclin during pump ...
Wulff J - - 1997
BACKGROUND: The Hemopump (DLP/Medtronic) has been in clinical use for about 7 years. There is still no adequate way of determining actual output from the three available pump systems in the clinical situation. If the pump is completely stopped during weaning from the device, there is a possibility of back-leakage ...
Atchison D J - - 1997
We used an actively contracting in vitro preparation of bovine mesenteric lymph vessels to study the effect of selected calcium channel modulators on the ability of these vessels to propel fluid. We found that blocking the dihydropyridine receptor with nifedipine and diltiazem inhibited pumping at concentrations within the range used ...
Messelink E J - - 1997
Multichannel Urethral Pressure Profilometry (MCUPP) is a method used to get more information on the pressure distribution within the female urethra. This information may be of value in the diagnostic work up of women with urinary incontinence. Different systems are used for this technique. The pump is an important part ...
Beaver K - - 1996
The balloon pressure waveform provides the clinician with a valuable tool for assessing the operating environment within the balloon and the catheter. The use of a calibrated balloon pressure waveform allows the clinician to assess gas leakage and catheter restriction alarms and implement corrective action. By combining assessment of the ...
Doty D B - - 1996
A device has been designed, constructed, and tested to provide pulsatile pressure/flow to a standard extracorporeal bypass circuit. The pulsatile augmentation device is pneumatically driven similar to an artificial heart ventricle except that there are no valves. It is constructed of polyurethane by vacuum forming and high frequency welding. Drivers ...
Zwarts M S - - 1996
A Stepper Motor Driven Reciprocating Pump (SDRP) can replace roller pumps and rotary pumps for cardio pulmonary bypass, hemodialysis and regional perfusion. The blood pumping ventricles are basically the same as ventricles used for air driven artificial hearts and ventricular assist devices. The electric stepper motor uses a flexible linkage ...
Wang S S - - 1996
Because of severe hemolysis, especially on producing pulsatile flow by changing the rotating speed of the impellers, the traditional centrifugal pump was rarely used for long-term support of the failing heart. We therefore developed a motor driven pulsatile implantable impeller pump. The pulsatility was achieved by changing the rotating speed ...
Lee M - - 1996
The aortic pressure (AoP) and pulmonary artery pressure (PAP) are important factors for the long-term survival of the patient receiving an implant of a total artificial heart (TAH). A new afterload regulation method using neural controllers has been developed for a moving actuator type TAH. Without any transducer, the proposed ...
Nakazawa T - - 1996
A cardiopulmonary support (CPS) device that incorporated a pneumatic ventricular assist device (VAD) and a membrane oxygenator was developed for the support of patients with profound heart and/or respiratory failure. This device has an advantage of being both a pulsatile assist device and membrane oxygenator. A "triple flow" regulator was ...
Gattuso J M - - 1996
The colonic motility response and short-term clinical effectiveness of colonic irrigation was studied in five patients with an end-colostomy, each of whom was studied on up to six occasions, using volumes of 500 and 1500 ml water infused under gravity and over a period of 2.5 and 5 min with ...
Bearnson G B - - 1996
A prototype bench top model of a continuous flow ventricular assist device using an impeller suspended by magnetic bearings has been developed. Generation of a pulsatile pressure was studied using both a computer model and in vitro loop tests of the prototype. The motivation for developing a computer model for ...
Fukamachi K - - 1996
Unlike in animal experiments, the pump orientation of a total artificial heart (TAH) can change remarkably in humans with the recipient's posture (upright, supine, or prone), thus affecting its filling characteristics. The left master alternate control mode of the Cleveland Clinic-Nimbus (CC-N) TAH adjusts beat rate by maintaining the left ...
Eya K - - 1996
The authors developed a new membrane oxygenator (MO) for long-term respiratory support and evaluated its performance in animal experiments for as long as 336 hr. The MO, with a membrane area of 1.2 m2 and priming volume of 140 ml, is compact and designed to be interposed in a ventricular ...
Gustafson K J - - 1996
Skeletal muscle ventricle (SMV) conditioning typically results in reduced muscle performance. This study investigated the effects of progressive SMV resting pressure expansion and dynamic muscle training on SMV pumping capability. SMVs were formed from latissimus dorsi muscle in five goats. Three experimental SMVs were conditioned against a compliant pneumatic implant ...
Camps J - - 1996
The influence of a simulated pulsatile pulpal pressure on the diffusion of NaCl through slices of human dentine (n = 12) was evaluated in vitro. The average hydraulic conductance of the slices of dentine was 0.0131 +/- 0.0031 microliter/cm2 per min per cmH2O(x +/- SD). A 1 mol/l NaCl solution ...
Ukoha O O - - 1996
BACKGROUND AND AIM OF STUDY: The prevalence of end-stage congestive heart failure and limitation of clinical alternative treatments present the need for creative new solutions. Formation of a ventricle from skeletal muscle (SMV) has shown promise in the animal laboratory. Two modes of the SMV for cardiac assistance, the counterpulsation ...
Müller E - - 1996
The objective of this study was to evaluate the principle technical requirements to servoregulate a centrifugal pump (Bio-Pump) and to discuss the potential risks and benefits of the potential use of such a device during long-term extra-corporeal support in an experimental laboratory study. A pressure control module (PCM) for the ...
Stamatelopoulos S F - - 1996
This work aims to determine optimal balloon shape and volume during left intraventricular balloon pumping (IABP) in the fibrillating dog heart. A balloon volume equal to the left ventricular end-diastolic volume (LVEDV) maintained a higher systolic aortic pressure and flow (106.4 +/- 2.7 mmHg and 84.7 +/- 2.35 ml/kg/min, x ...
Yambe T - - 1996
We have studied the fluctuations of an artificial circulation for the analysis of the physiological aspects; however, the conventionally used fast Fourier transform (FFT) method cannot separate harmonic oscillations, such as respiratory and Mayer waves, from the 1/f fluctuation, which has been though to represent underlying fractal dynamics. Fractal structure ...
Scott D A - - 1996
Resistance to fluid infusion can be derived from measurements of pressure at two or more flow rates. We measured resistance in 31 patients using a pressure-monitoring infusion pump (Model 560, IVAC) by recording pressure at five flow rates (0, 50, 100, 200, and 300 mL/hr), and computing resistance as the ...
Sassoon C S - - 1996
The time course of ventilatory failure, pump failure, and diaphragm peripheral fatigue was determined during the application of external inspiratory resistive loads (IRL) in anesthetized rabbits. Pump failure is defined as the inability of the diaphragm to sustain the expected force under IRL. To assess contractile fatigue, transdiaphragmatic pressures (Pdi) ...
Meyns B - - 1996
The Hemopump is a useful left ventricular assist device. Because it is a rotary blood pump, the pump performance is not constant and is dependent on the cardiac cycle. We measured the static flow delivered by the pump at varying pressure heads (delta P) in a mock circulation. These data ...
Curtis J - - 1996
The purpose of this experiment was to study the effects of the St. Jude Lifestream centrifugal pump on hemodynamic and hematologic parameters and the incidence of postmortem findings in a subchronic ex vivo left ventricular assist animal model. Five calves were implanted with the pump as a left ventricular assist ...
Konishi H - - 1996
A rotary blood pump inherently provides only one noninvasive "observable" parameter (motor current) and allows for only one "controllable" parameter (pump speed.) To maintain the systemic circulation properly, the pump seed must be controlled to sustain appropriate outlet flows and perfusion pressure while preventing pulmonary damage caused by extremes in ...
Montoya J P - - 1996
A prototype of a non-occlusive pressure-regulated blood pump (M-pump) was evaluated in-vitro for safety in a comparative study with the roller and centrifugal pumps. The M-pump consists of collapsible tubing of unique design wrapped under tension around a rotor without a stator. The prototype M-pumps were tested in vitro to ...
Mitsui N - - 1996
A computer simulation was carried out to investigate the influence of nonpulsatile left ventricular assistance on hemodynamics. A simulation circuit was constructed to represent the circulatory system. A source of current was added to denote the nonpulsatile blood pump. The left and right ventricles were replaced by variable compliances. Left ...
Steinmetz J A - - 1996
This study compared tissue interface pressures (TIPs) on the occiput of 25 volunteer patients undergoing coronary artery bypass graft (CABG) surgery. Pressures were measured using the Gaymar pressure gauge and electropneumatic sensor before and after induction of anesthesia, after the patient was placed on the cardiopulmonary bypass pump, every 30 ...
Odaguchi H - - 1996
A special extraaortic balloon was developed that can be placed around the ascending aorta. This balloon can easily support the heart temporarily in a median sternotomy field, especially in cases in which it is difficult to use intraaortic balloon pumping because of peripheral arterial disease. The goal of this study ...
Sich B - - 1996
Endogenous digitalis-like factors in humans are presumably cardenolides and bufadienolides. To test whether bufadienolide-like substances may circulate in human blood, we used antibodies from rabbits against the bufadienolide proscillaridin A to measure the concentration of cross-reacting material in human plasma with an indirect enzyme-linked immunosorbent assay. IgG had an apparent ...
Kao T W - - 1996
A new configuration for a pressure sensor in which the motion of a diaphragm produces strain in a fiber Fabry-Perot interferometer (FFPI) is described. The single-mode fiber containing the interferometer is bonded at one end to the stainless-steel diaphragm. The fiber is also attached beyond the interferometer to the sensor ...
Nakazawa T - - 1996
The pivot bearing centrifugal blood pump was developed as a long-term centrifugal ventricular assist device (VAD) as well as a cardiopulmonary bypass pump. This pivot bearing supported centrifugal pump with an eccentric port (CIE) incorporates a seal-less design with a blood stagnation-free structure. This pump can provide flows of 12 ...
Undar A - - 1996
Cardiopulmonary bypass surgical techniques that allow a surgeon to operate on the infant's heart use an extracorporeal circuit consisting of a pump, oxygenator, arterial and venous reservoirs, cannulae, an arterial filter, and tubing. The extracorporeal technique currently used in infants and neonates is sometimes associated with neurologic damage. We are ...
Murakami T - - 1996
A totally implantable motor-driven left ventricular assist device (LVAD) has been developed and tested. The performance of this LVAD was tested in a mock circulatory system. This pump provided 8 L/min of output against a mean afterload of 120 mm Hg with a filling pressure of 20 mm Hg when ...
Shaeffer J - - 1996
To evaluate the efficacy of a microwave radiometry system in detecting in-line air emboli in radiographic contrast media, air emboli ranging in volume from 0.1 to 0.005 ml were introduced into ionic (ioxaglate) and nonionic (iohexol) contrast media at 22 or 37 degrees pumped at flow rates of 16.7, 180 ...
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