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PubMedDate not supplied

In vivo and in vitro evaluation of the pulsatile mode of a magnetically suspended centrifugal pump.

The authors have been developing a magnetically suspended centrifugal pump (MSCP). They have devised a pulsatile mode for the MSCP, which was generated by altering rotational speed. This article describes in vitro and in vivo studies with the pulsatile mode of the MSCP. Hemolysis tests were performed in two identical circuits to compare the nonpulsatile (NP) mode and the pulsatile (P) mode. In vivo studies were performed in sheep. First, biventricular assisted circulation was instituted in the left heart with the MSCP and in the right heart with the Biopump. The native heart was induced to ventricular fibrillation. Second, a left ventricular assisted circulation was instituted as the native heart was beating. An inflow cannula was inserted into the left atrium in one sheep and into the left ventricle in the other. The normalized indices of hemolysis of the NP and P groups were 0.0025 +/- 0.0018 g/100 L, and 0.0032 +/- 0.0024 g/100 L (N = 4, not significant). During ventricular fibrillation in the P mode, the pulse pressure was 14 mmHg (the rotational speed: 1,500 to 2,600 rpm). In a beating heart, at atrial withdrawal, the pulse pressure increased from 10 to 24 mmHg (2,100 +/- 500 rpm), while at ventricular withdrawal, it decreased from 17 to 40 mmHg (2,000 +/- 500 rpm) on P mode. The MSCP in pulsatile mode did not increase hemolysis. At ventricular withdrawal, it was easier to produce a pulsation than at atrial withdrawal. The pulsatile mode of the MSCP is applicable to a left ventricular assist system.

Animals↗
PubMed1991

[Mitral valve disease with pulmonary hypertension: two surgical cases].

Two surgical cases of mitral valve disease with severe pulmonary hypertension were reported, in which pulmonary hypertensive crisis (PHC) was a really serious problem to be treated. The first case (60-year-old woman) had atrial fibrillation and her pulmonary artery pressure was 68/32 mmHg (Pp/Ps = 0.63) and mean pulmonary wedge pressure was 26 mmHg with a high v wave (46 mmHg). PHC developed immediately after the cessation of artificial cardiopulmonary bypass, and intraaortic balloon pumping was performed. However, it was difficult to wean from the assist circulation, and then PGE1 and isoproterenol were given into the pulmonary artery and epinephrine and norepinephrine were given into the left atrium, and we succeeded in weaning from the assist circulation. The second case (58-year-old woman) had high pulmonary artery pressure (86/37 mmHg) and the Pp/Ps was 0.73. According to the experience of the first case, prevention of PHC started during cardiopulmonary bypass, giving PGE1, nitroglycerin and torazoline into the pulmonary artery. This led to the easy weaning from cardiopulmonary bypass. PHC may be seen even in cases of acquired valvular disease, and the prevention is mandatory for uneventful surgery.

Cardiopulmonary Bypass↗
PubMed1997

Continuous transoesophageal echocardiography monitoring during weaning from cardiopulmonary bypass in children.

The purpose of this study was to evaluate the effectiveness of transoesophageal echocardiography monitoring during weaning from cardiopulmonary bypass after intracardiac repair in children. The left ventricular ejection fraction, left ventricular end-diastolic volume and left ventricle wall motion were monitored continuously by transoesophageal echocardiography in controls weaned easily from cardiopulmonary bypass (group A, n = 25), and those weaned with difficulty from cardiopulmonary bypass after mechanically assisted circulation (group B, n = 16). In group A, left ventricular ejection fraction and left ventricle wall motion were within normal range, and did not change significantly during weaning after cardiopulmonary bypass when compared with pre-bypass data. In contrast, left ventricular ejection fraction, left ventricular end-diastolic volume and left ventricle wall motion in group B during the first trial of weaning from bypass were significantly worsened. Hence, assisted circulation was performed until the data obtained via transoesophageal echocardiography improved with regard to maintenance of fluid balance, catecholamine dosage and assisted pump flow. All cases in group B were weaned safely from cardiopulmonary bypass despite their critical condition. In conclusion, continuous transoesophageal echocardiography monitoring may be a useful tool in children with severe heart failure for safe weaning from cardiopulmonary bypass after intracardiac repair.

Adolescent↗
PubMedDate not supplied

[Hydrodynamic and technological bases of a new design of the automyoneoventricle in assisted blood circulation].

The paper presents evidence for and results of development of a new hydrodynamic optimized design of the automyoneoventricle (AMNV) for extracorporeal circulation in critical myocardial lesions. The chosen geometry of externally spirally braided AMNV forms a curled flow that excludes the presence of eddy and stagnant zones which present a risk for thrombogenesis. Moreover, the paper details the original process for manufacturing the prototypes of the AMNV having spiral latex ribs, which has been modified to give its thromboresistant and antibiotic properties. The proposed biomechanical system has been put through tests yielding satisfactory results and it is to undergo clinical trials.

Animals↗
PubMed1984

Soliton-assisted unidirectional circulation in a biochemical cycle.

The unidirectional circulation of an enzyme round a working cycle can be understood in terms of the formation and decay of a soliton that acts as a ligand for the protein and for which the surrounding heat bath serves as a sink. An experimental confirmation of this interpretation is suggested in which the soliton is of the Davidov type and is created by infrared photon absorption as in recent experiments on acetanilide.

Journal Article↗
PubMed2006

The possibility of a veno-arterial bypass system using the Abiomed BVS 5000.

Effect of Abiomed BVS 5000 (Cardiovascular Inc., Danvers, MA, U.S.A) has been reported for mechanical assist circulation in cardiogenic shock. However, this pump is generally used as a ventricular assist device, not as a device for veno-arterial bypass. Therefore, we evaluated its effectiveness through an experiment. The left anterior descending branch of pigs' heart was ligated to prepare a model of acute myocardial infarction, and after the onset of cardiogenic shock, circulation was initially supported for 30 min using the BVS 5000, followed by support for another 30 min using a Gyro pump (Gyro, Kyocera, Inc., Kyoto, Japan). Subsequently, circulation was additionally supported for 30 min using both a Gyro and an intra-aortic balloon pump (IABP) (Tokai Medical Inc., Aichi, Japan) (Gyro + IABP). Circulation was supported in each group at 30-min intervals in the reversed order of assisted circulation. Although the mean aortic pressure, pump flow, and total flow were not significantly different among the three setups, the pulse pressure was 48.2 +/- 3.3, 12.2 +/- 2.2, and 29.9 +/- 3.8 mm Hg in Abiomed, Gyro, and Gyro + IABP, respectively. Although neither coronary arterial nor myocardial blood flow showed significant differences among the three setups, the renal arterial blood flow was significantly larger in BVS 5000 compared to the other two setups. In this study, we selected an alpha-cube (Platium Cube NCVC 6000, Edwards Research Medical Inc., Salt Lake City, UT, U.S.A.), which is considered as an oxygenator that produces minimum pressure loss. Therefore, the pulsatile flow we obtained with the Abiomed was maintained even after we started using the oxygenator. The pulsatile flow had positive effects on renal circulation and peripheral circulation.

Animals↗
PubMed1988

Left heart assistance with the spindle pump.

The spindle pump--a new attempt at assisted circulation--was developed to prevent the main problems of nonpulsatile blood pumps, i.e. traumatic hemolysis, thrombus formation and sealing. It was essential to achieve adequate output with the lowest possible speed in order to minimize traumatic hemolysis. The result was a spindle pump with three windings in a U-shaped housing driven by an electric motor. Many tests were necessary to establish a prototype. The spindle was completely redesigned several times to reach an acceptable volume output and corresponding pressure output. In animal experiments this final prototype working as a LVAD, with a speed of 5400 RPM circulates 4 liters/min against BP of 110 mmHg. The hemolysis rate has been low in acute and survival experiments (27 hours up to now), and is between 25 and 30 mg/100 ml of free hemoglobin, thus within the normal range.

Animals↗
PubMedDate not supplied

The internal ventricular venting loop catheter. A new, simplified, single cannulation approach for a ventricular assist system.

The internal ventricular venting loop (IVVL) catheter is a coaxial, two lumen, bidirectional flow cannula introduced peripherally and advanced intraluminally to the pulmonary artery by its flow directed, balloon tipped inner tubing in a right ventricular assist system (RVAS), or to the left ventricle over a guide wire under fluoroscopy in a left ventricular assist system (LVAS). Its use was successfully tested in six acute canine experiments using a small IVVL catheter. Hemodynamic responses to increasing roller pump flow rates, to a maximum of 1 L/min, were initially measured. Then, hemodynamic changes to 600 ml/min, after left anterior descending artery ligation (in IVVL-LVAS) and 300 ml/min after right coronary artery ligation (in IVVL-RVAS) were regularly recorded every 15 min until cardiac arrest. The IVVL-LVAS was able to significantly decrease the pulmonary capillary wedge pressure, while the IVVL-RVAS was able to significantly decrease the central venous pressure. The IVVL system was able to partially unload the ventricles and restore about 33-60% of the cardiac output. However, it could not effectively support the heart during arrest. Thus, the IVVL catheter can facilitate simple and effective single cannulation for either RVAS or LVAS. This approach may enable ordinary cardiac centers to make use of already available blood pumps for temporary, inexpensive, and less invasive application of partially assisted circulation when intra aortic balloon pump assistance fails.

Animals↗
PubMed1989

[Successful repair of tetralogy of Fallot with severe right ventricular dysfunction using veno-arterial bypass in an adult].

A 35-year-old male with tetralogy of Fallot, who had undergone left Blalock-Taussig shunt at ten year old, developed severe dysfunction of right ventricle with decreased right ventricular ejection fraction of 25% and frequent premature ventricular contractions of right ventricular origin. Following intracardiac procedure, the venoarterial assist circulation was successfully employed for 9 hours, until his hemodynamic conditions were improved. This experience reemphasized the importance of right ventricular protection and mechanical circulatory assist in the surgical treatment of Fallot's tetralogy in older children and adults who developed severe right ventricular dysfunction as a natural history of this disease.

Adult↗
PubMed1997

The method for keeping low perfusion flow weaning from centrifugal pumps: an evaluation of hemolysis in the circulator units.

Currently, the clinical application of extracorporeal and assisted circulation using centrifugal pumps is becoming popular. However, a problem in the use of centrifugal pumps is the difficulty in controlling the flow rate when it is a low range. Although we have been controlling the flow rate with a control unit that simply squeezes the blood outlet tube from the outside, hemolysis resulting from turbulent flow in the tube was discovered. Therefore, this control procedure was evaluated experimentally. Two groups were tested as follows: in Group A (n = 10), the tube was squeezed from the outside using the control unit, and in Group B (n = 10), no control unit was used. Blood in each circuit was circulated at 1,500 rpm, and the flow rate was controlled to 250 ml/min using the control unit for Group A. Time-course changes of lactate dehydrogenase (LDH) and free hemoglobin in the blood were measured during 8 h of circulation. There were no significant differences between the 2 groups in the mean values of LDH and free hemoglobin. Therefore, the present low flow rate control provided by the control unit makes it appear to be a simple and useful apparatus for controlling blood circulation using centrifugal pumps.

Analysis of Variance↗
PubMedDate not supplied

[Effect of hyperbaric oxygenation on central hemodynamics and oxygenating function of the lungs in open-heart surgery].

The dynamics of some oxygenating pulmonary function (OPF) indices has been studied in 33 patients with coronary cardiac disease and rheumatic lesions of cardiac valves 4-6 hours after surgery in response to a single hyperbaric oxygenation (HBO) session (1.5 ata, 45 min) in the immediate postoperative period. It is found that in the presence of slight or, on the contrary, pronounced arterial hypoxemia, no significant negative OPF changes were observed. At the same time, a temporary increase in the alveolo-arterial gradient has been found in some patients. The comparison of data on the systemic blood flow with the OPF indices permits suggesting the prevalent role of the membrane component in a PaO2 decrease in patients after using assisted circulation.

Adult↗