Cardiac intervention, myocardial infarction, or postoperative heart failure will sometimes create a need for circulatory support. For this purpose, a new, minimally invasive intra-aortic cardiac support system with a foldable propeller has been developed. In animals, the pump has been shown to have a positive hemodynamic influence, and the present ...

A conductance and arterial pressure based method (1/R control) to determine the cardiac output (CO) of a total artificial heart (TAH) was developed to provide a central nervous system with control over the output of TAH. In order to clarify the deference in hemodynamic response between natural heart and 1/R ...

The relative contributions to gastric emptying from common cavity antroduodenal pressure difference ("pressure pump") vs. propagating high-pressure waves in the distal antrum ("peristaltic pump") were analyzed in humans by high-resolution manometry concurrently with time-resolved three-dimensional magnetic resonance imaging during intraduodenal nutrient infusion at 2 kcal/min. Gastric volume, space-time pressure, and ...

We investigated the effects of two new hollow-fiber membrane oxygenators, the Capiox SX10 and the Lilliput 901, on pulsatile versus nonpulsatile perfusion in an in vitro model designed to simulate a 3 kg infant. The experiments were divided into eight groups (six pulsatile and two nonpulsatile), according to the equipment ...

At a machining center used to produce transmission parts, aerosol instrumentation was used to quantitatively study mist generation and to evaluate the performance of an air cleaner for controlling the mist. This machining center drilled and tapped holes at rotational speeds of 1000 to 3000 rpm. During most machining operations, ...

The plethysmograph, a useful, non-invasive circulatory assessment capability featured on most modern pulse oximeters, provides a waveform representation of pulsatile peripheral blood flow, from which can be drawn assessments of both the peripheral and central circulation. Implementation and maintenance of plethysmography monitoring is straightforward and uncomplicated by virtue of its ...

OBJECTIVE: To show the effect of myocardial support by micropumps during beating heart CABG for triple vessel disease. METHODS: In 12 sheep, three coronary arteries (LAD, intermediate branch and circumflex) were consecutively occluded for 10 min. The animals were divided in two groups: group 1 without support (n=6) and group ...

Malfunction of electronic medical support apparatus utilized in the ICU usually causes system failure. We report several occurrences of a potentially dangerous interaction between a continuous veno-venous hemodialysis (CVVHD) system and an intra-aortic balloon pump (IABP) counterpulsation device in four patients requiring both systems. The patients had acute renal failure ...

Displacement of the heart to expose the left circumflex artery (LCX) causes hemodynamic disturbance during off-pump coronary artery bypass grafting (CABG). We applied right heart bypass (RHB) using a heparin-coated centrifugal pump without an oxygenator in an attempt to stabilize the hemodynamics. Five mongrel dogs (15.5-20 kg) were used. Hemodynamic ...

In human perception, the heart was not always part of the blood circulating system. It was later included as a suction pump until Harvey argued that the heart is actually a compression pump, the central organ of the circulation, and the only organ responsible for the motion of blood. Considered ...

The purpose of this study was to evaluate the early changes in sarcoplasmic reticulum (SR) function and the parallel morphological and hemodynamic modifications occurring in the heart following pressure overload. As regards SR function, we also explored the levels of acylphosphatase, an enzyme which might have a regulatory effect on ...

Unlike the mechanisms of intraaortic balloon pump (IABP) support, the mechanisms by which transvalvular axial flow Hemopump (HP) support benefit dysfunctional myocardium are less clearly understood. To help elucidate these mechanisms, hemodynamic, metabolic, and mechanical indexes of left ventricular function were measured during conditions of control, ischemic dysfunction, IABP support, ...

Augmented venous drainage improves venous return during minimally invasive cardiac surgery. Two systems to augment drainage are common: in one, a centrifugal pump draws blood from the venous site and pumps it into a venous reservoir. In the other, suction is applied directly to a hard-shell venous reservoir. Both systems ...

The purpose of this study was to quantify and compare pulsatile and nonpulsatile pressure and flow waveforms in terms of energy equivalent pressure (EEP) during cardiopulmonary bypass in a neonatal piglet model. EEP is the ratio of the area under the hemodynamic power curve and the flow curve. Piglets, mean ...

OBJECTIVE: The intra-aortic cannula pump is a catheter pump designed to support the acutely failing heart. It expels blood from the left ventricle into the ascending aorta in a pulsatile flow pattern. The aim of the study was to analyze the hemodynamic performance of this new intracardiac support system in ...

The total artificial heart (TAH) being developed by these authors successfully completed hydrodynamic and hemolysis studies followed by two acute implantations. Before commencing preclinical studies on any device, documentation of the reliability and durability of each component has to be done. This TAH was submitted to a 4 month destruction ...

Hemodynamics stands on three main physical principles: the hydrostatic pressure, firstly described by Stevino, the viscous flow pressure, described by Poiseuille and the total hydraulic energy, or Bernoulli's equation. However, neither of these physical principles gives a comprehensive description of the single pressure measurement in the cardiovascular system. Hence, all ...

Leading international institutions are designing and developing various types of ventricular assist devices (VAD) and total artificial hearts (TAH). Some of the commercially available pulsatile VADs are not readily implantable into the thoracic cavity of smaller size patients because of size limitation. The majority of the TAH dimensions requires the ...

Several clinical and animal studies have demonstrated that pulsatile perfusion is more beneficial than nonpulsatile perfusion during short or long durations of extracorporeal circulation. Other investigators, however, have been unable to document these benefits. The issue remains controversial. Central to the debate is the issue of a precise definition of ...

A vibrating flow pump (VFP) can generate high frequency oscillated blood flow within 10-30 Hz by the oscillation of its central tube. A totally implantable artificial heart using a VFP is being developed as a unique type of blood pump. In this study, left ventricular (LV) assist circulation was performed ...

BACKGROUND: Use of cardiopulmonary bypass for emergency resuscitation is not new. In fact, John Gibbon proposed this concept for the treatment of severe pulmonary embolism in 1937. Significant progress has been made since, and two main concepts for cardiac assist based on cardiopulmonary bypass have emerged: cardiopulmonary support (CPS) and ...

A fatal outcome is expected in a left ventricular assist system (LVAS) utilizing a rotary blood pump if there is no mechanism to prevent the backflow from the aorta to the heart in the case of acute pump failure. To solve this problem, a passive mechanical clamping system at the ...

When arthroscopy of the temporomandibular joint (TMJ) is performed, we often observe differences in the resistance of hydraulic pressure during intra-articular pumping. It can be speculated that intra-articular adhesion and contracture of the capsule and ligament may cause these differences in resistance. In order to measure the changes in intra-articular ...

After observing micro-bubble activity in the venovenous bypass system during liver transplantation, an experiment was designed to investigate the origin of these bubbles and to define the conditions under which they occurred. Using a Biomedicus constrained vortex pump and a customized circuit design, microbubble activity was measured in saline and ...

Before, during, and after cardiac intervention, there is occasionally a need for circulatory support because of hemodynamic deterioration. For this purpose, a new minimally invasive cardiac assist device has been developed, and an early prototype has been studied in a bench test and in three pigs. The pump is a ...

An in vitro pulsatile pump flow system that is capable of producing physiologic pressures and flows in a mock circulatory system tuned to reproduce the first nine harmonics of the input impedance of a rhesus monkey was developed and tested. The system was created as a research tool for evaluating ...

Arthroscopic irrigation/distention systems (AI/DSs) are used during endoscopic orthopedic procedures to keep the cavity of a joint (such as the knee or shoulder) filled with pressurized distention solution. This expands the joint, thereby improving visualization. Controlled release of this solution from the joint is used to flush out debris. For ...

We investigated possible functional changes in the vascular system accompanying the morphological change in prolonged nonpulsatile left heart bypass (LHB). Three adult goats underwent pulsatile LHB. Two weeks postoperatively, the pulsatile ventricular assist device was replaced with a centrifugal pump and nonpulsatile LHB was subsequently conducted for 4 weeks. The ...

A controversial hypothesis has proposed that lizards are subject to a speed-dependent axial constraint that prevents effective lung ventilation during moderate- and high-speed locomotion. This hypothesis has been challenged by results demonstrating that monitor lizards (genus Varanus) experience no axial constraint. Evidence presented here shows that, during locomotion, varanids use ...

OBJECTIVES: to explore the hydrodynamic mechanisms involved in the regulation of ambulatory venous pressure. DESIGN: an experimental model of calf venous pump was constructed with collapsible tubes and valves. MATERIAL: the model consisted of a conduit and a pump with an intervening competent valve. Another valve that could allow reflux ...

The response of a continuous flow magnetic bearing supported ventricular assist device, the CFVAD3 (CF3) to human physiologic pressure and flow needs is varied by adjustment of the motor speed. This paper discusses a model of the automatic feedback controller designed to develop the required pump performance. The major human ...

AIMS: The present study was undertaken to determine the absolute systemic availability of budesonide from three different devices for nasal administration: pressurized aerosol, aqueous pump spray, and powder. METHODS: Sixteen healthy, non-smoking, volunteers participated in this open, randomized, and crossover study. All subjects received budesonide as an intravenous dose of ...

A novel integrated heart-lung assist device has been developed as a simple to use portable cardiopulmonary support system. The device comprises a centrifugal pump and an artificial lung, which is located around the pump, in an all in one system. The special membrane employed precludes plasma breakthrough in protracted use ...

A simple two-pump model has served to describe the mechanics of ventilation in cartilaginous and bony fishes since the pioneering work of G. M. Hughes. A hallmark of this model is that water flow over the gills is continuous. Studies of feeding kinematics in the swellshark Cephaloscyllium ventriosum, however, suggested ...

The use of the intraaortic balloon pump (IABP) for managing acute left ventricular failure in pediatric patients is less successful than in adults. It is often reported that rapid pediatric heart rates make accurate timing difficult to achieve. Traditional IABP theory requires that the balloon inflate during diastole (after aortic ...

A pneumatic ventricular assist device (Sarns/3M) has been redesigned for low volume hydraulic actuation to accommodate muscle powered drive systems. Design modifications include adding a bellows/piston mechanism (to compress the blood sac) and a compliance chamber for volume compensation. A simple prototype device was constructed to measure the efficacy of ...

We developed an electrohydraulic ventricular assist device with magnetic coupling. The integrated system consists of a blood pump, a water conduit for pressure transmission, a bellows type pumping sac, an actuator for transforming the circular motion of a motor to the linear motion of a pusher plate attached to the ...

Total Artificial Heart (TAH) development at Penn State University and 3M Health Care has progressed from design improvements and manufacturing documentation to in vitro and in vivo testing to characterize the system's hemodynamic response and energetic performance. The TAH system is completely implantable and intended for use as an alternative ...

BACKGROUND: The enabler circulatory support system is a catheter pump which expels blood from the left or right ventricular cavity and provides pulsatile flow in the ascending aorta or pulmonary artery. It is driven by a bedside installed pulsatile driving console. The device can easily be implanted by a minimal ...

A computer-controlled tensiometer for studying wall tension in tubular organs has been developed. The system consisted of a probe with an inflatable balloon, an impedance planimeter, pressure transducer and amplifier, a pump with RS232 interface and a PC with dedicated software. Circumferential wall tension was computed in real time from ...

Ephedrine is widely used to elevate blood pressure, however, one should be cautious to use it concomitantly with phenytoin infusion in neurosurgical procedures. A 59-year-old female was admitted for craniotomy with removal of metastatic brain tumor. During operation phenytoin infusion was given to forestall postoperative seizure. Hypotension, bradycardia and complete ...

A new type of energy converter for an electro-mechanical total artificial heart (TAH) based on the principle of a unidirectional moving motor is described. Named the TAH Serpentina, the concept consists of 2 major parts, a pendulum shaped movable element fixed on one side using a joint bearing and a ...

Articular cartilages are exposed to significant loads in vivo, which by their effects on chondrocyte metabolism can alter the mechanical properties of the extracellular matrix. The mechanism(s) by which chondrocytes sense and respond to load are not well understood. One component of load, hydrostatic pressure, can be studied independently of ...

This paper focuses on the evaluation of dynamic pumps as an element of the assist unit from the standpoint of its capacity to pass and change the left ventricle's pulsations. Analyses of the dynamic equations of the pipelines and pump have been performed. The pump intensification capacity of the disc ...

PURPOSE: We analyzed the mechanism of effects of intra-aortic balloon pumping using the pressure-volume relationship and ventriculoarterial coupling in the normal and failing hearts. MATERIALS: In 12 anesthetized Holstein calves (weight, 94 +/- 8 kg), the ventricular end-systolic and arterial elastances, pressure-volume area, and external work were analyzed during steady-state ...

An alternate physiologic pulsatile pump (PPP) system was designed and evaluated to produce sufficient pulsatility during neonate-infant open heart surgery. This hydraulically driven pump system has a unique "dual" pumping chamber mechanism. The first chamber is placed between the venous reservoir and oxygenator and the second chamber between the oxygenator ...

A simplified model for the arterial pressure control system was implemented on a personal computer using Matlab Simulink. Model responses to variations of systemic vascular resistance were comparable to those predicted by physiology. Computer simulation suggested that including this model of the internal pressure control system within the design of ...

We tested the hypothesis that CO2 and heat have different effects on the ventilatory pattern of grasshoppers Melanoplus differentialis. Eight grasshoppers were sealed between rostral (inspiratory) and caudal (expiratory) spiracles in separated, airtight, chambers and pressure changes were measured. Normal breathing patterns decreased pressure in the rostral chamber and increased ...

OBJECTIVE: To determine the acceptability and reproducibility of a novel method of measuring calf muscle pump efficiency (CMPE). If confirmed, to examine if the results had implications for the use of elastic compression stockings. EXPERIMENTAL DESIGN: A system devised to measure pressure/volume relationships in the calf during simulated ambulation and ...

Blood flows and recirculations with standard and reversed direction of lines were measured by chemical (urea and creatinine) and ultrasound dilution (saline) methods in 47 chronic hemodialysis patients. Thirty-seven patients had 47 dual-lumen, central vein (CV) catheters: 32 were PermCath (Quinton Instruments Company, Seattle, WA), 6 were Access Cath (MEDCOMP, ...