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At least 577 records · Page 32Linked to original sources
PubMed1999

Optimal pulse pressure of pulmonary circulation under bi-ventricular assist after cardiogenic shock.

In order to evaluate an appropriate pulse pressure of pulmonary circulation during bi-ventricular assist, an experimental study was carried out in swine. The cardiogenic shock model was made by the left anterior descending (LAD) ligation method. When the hear fibrillated due to acute myocardial infarction, both left and right hearts were supported by ventricular assist devices (VADs) for two hours. The left heart assist was operated with a pneumatic pulsatile ventricular assist device (VAD) and the right was operated with a pneumatic VAD or centrifugal pump. According to the pulse pressure of the pulmonary artery these models were divided into three groups: Low-P group (n = 3), in which a low pulse pressure (less than 20 mmHg) was made by VAD, High-P group (n = 5), in which over 20 mmHg of pulse pressure was initiated. NP group (n = 10), in which nonpulsatile assist was done with a centrifugal pump. In pulmonary gas exchange, the Low-P group was superior to the other two groups. The average PaO2 was 214+/-57 mmHg in the Low-p group, and 117+/-41 mmHg and 148+/-81 mmHg in the NP group and High-P group respectively. In the pathological study, a remarkable extension of pulmonary lymphoducts was found in the High-P group. On the other hand, this change was not recognized in other groups. These results suggested that pulmonary microcirculation might deteriorate due to high pulse pressure of the pulmonary artery. We consider the most suitable pulmonary pulse pressure to be around 20 mmHg to maintain normal pulmonary circulation.

Animals↗
PubMed2004

Development of an implantable undulation type ventricular assist device for control of organ circulation.

It is well known that a rotary blood pump (RP) is effective as a small ventricular assist device (VAD). It might be still more effective if pulsation was available. The undulation pump (UP), which is a type of small RP, can also produce pulsation. In Japan, a development project for an implantable type UP ventricular assist device (UPVAD) is now advanced. Six universities and some companies together have been in charge of the development project for 5 years. In this study, the influence which the UP under development has on circulation in internal organs was investigated. Goats with the same weight as an average Asian person were used for the experiment. The left chest cavity was opened after resection of the fourth rib and the heart was approached. A cannula was inserted in the left ventricle from the apex. An outflow cannula was inserted into the left descending aorta. Heart muscle was excised using a newly developed puncher. The UPVAD was implanted using a left-heart bypass system. The myocardial blood flow, carotid arterial blood flow, and the kidney blood flow were recorded together with an electrocardiogram, blood pressure, and the flow rate. In these animal experiments, the blood circulation dynamic state was stabilized and sufficient support of the left heart was observed. Myocardial blood flow, carotid arterial flow, and a kidney blood flow increase resulting from UPVAD support was observed. Often the problem of multiple organ failure is important at the time of clinical application of a ventricular assist device. Assisting circulation to internal organs is important for prevention of multiple organ failure. It was concluded that the UPVAD might be useful for prevention of multiple organ failure.

Animals↗
PubMed1996

[Development of circulatory support during 420 aneurysm resections of the descending thoracic aorta].

From July 1974 to January 1996, 420 aneurysms of the descending thoracic aorta were surgically treated at l'Hôpital du Sacré-Coeur de Montréal. Three principles were previously established and rigorously respected: 1) the preservation of distal body perfusion, 2) the briefest aortic cross-clamp time realizable (mean: 29.8 +/- 16 minutes overall, reduced to a mean of 24 +/- 6 minutes for the last 250 cases), 3) keep the aortic resection as short as possible in order to preserve as many intercostal arteries as possible (10 cm or less in 91.6% of the cases). In the first 380 cases, distal aortic circulation was supported with a 9 mm Gott shunt without using systemic heparinization. Average shunt flows from 300 ml/min, to 4900 ml/min. (mean: 2497 +/- 813 ml/min.), average proximal pressures from 80 to 200 mmHg (mean: 146 +/- 17 mmHg) and average distal pressures from 15 to 150 mmHg (mean: 64 +/- 19 mmHg) were recorded. In the last 40 cases, the distal circulation was supplied through the left heart assistance device Bio-Medicus using minimal systemic heparinization (0.5 mg/kg), (target ACT > 150 seconds). Average pump flows from 1800 ml/min to 5200 ml/min. (mean: 3340 +/- 866 ml/min.) were obtained. Average proximal pressures from 90 to 200 mmHg (mean: 118 +/- 19 mmHg) and average distal pressures from 58 to 180 mmHg (mean: 95 +/- 24 mmHg) were recorded. Overall hospital mortality is 11.9% (50/420 cases) and 9.9% when ruptured aneurysms are excluded. Paraplegia occurred in 2 patients (0.4%) and one was related to an unfunctional Gott shunt. Adverse anatomical conditions like a proximal aneurysm, degenerative changes of the aortic wall, a previous proximal graft replacement or the presence of coronary artery bypass grafts, a friable wall encountered with dissecting aneurysms and also an adverse physiological condition like a left ventricular dysfunction prompted us to modify the circulatory support by using the left heart bypass. Comparison of both methods of perfusion supported by statistical analysis regarding shunt and pump flows, proximal and distal perfusion pressures has showed the physiological superiority of the centrifugal pump that we have now routinely adopted.

Adolescent↗
PubMedDate not supplied

Coupling pediatric ventricle assist devices to the Fontan circulation: simulations with a lumped-parameter model.

In pediatric ventricular assist device (VAD) design, the process of matching device characteristics and dimensions to the relevant disease conditions poses a formidable challenge because the disease spectrum is more highly varied than for adult applications. One example arises with single-ventricle congenital defects, which demand palliative surgeries that create elevated systemic venous pressure and altered pulmonary hemodynamics. Substituting a mechanical pump as a right ventricle has long been proposed to eliminate the associated early and postoperative anomalies. A pulsatile lumped-parameter model of the single-ventricle circulation was developed to guide the preliminary design studies. Two special modules, the pump characteristics and the total cavopulmonary connection (TCPC) module, are introduced. The TCPC module incorporates the results of three-dimensional patient-specific computational fluid dynamics calculations, where the pressure drop in the TCPC anastomosis is calculated at the equal vascular lung resistance operating point for different cardiac outputs at a steady 60/40 inferior vena cava/superior vena cava flow split. Preliminary results obtained with the adult parameters are presented with no ventricle remodeling or combined larger-size single ventricle. A detailed literature review of single-ventricle function is provided. Coupling a continuous pump to the single-ventricle circulation brought both the pulmonary and systemic venous pressures back to manageable levels. Selected VADs provided an acceptable cardiac output trace of the single left ventricle, after initial transients. Remodeling of the systemic venous compliance plays a critical role in performance and is included in this study. Pulsatile operation mode with rotational speed regulation highlighted the importance of TCPC and pulmonary artery compliances. Four different pumps and three patient-specific anatomical TCPC pathologies were studied. Magnitudes of the equivalent TCPC resistances were found to be comparable to the vascular resistances of the normal baseline circulation, significantly affecting both the VAD design and hemodynamics.

Anastomosis, Surgical↗
PubMed1993

[Newly-developed catheter for cardio-renal assist during intraaortic balloon counterpulsation].

A new catheter was developed for the cardio-renal assist during intra-aortic balloon counterpulsation. The catheter consists of both a large balloon of conventional IAB (TMP balloon) located at the distal end of the catheter and an additional small balloon 10 cm distant from the large balloon with common lumen and single shaft. Experimental study was carried out in the mock circulatory system simulating the descending aorta employing a conventional IAB catheter as a control. It was demonstrated that the flow in the mid portion between both balloons could be increased maximally by as much as 28% of that of the control under the continuous flow and 214% under the pulsatile flow. The double balloon catheter was considered to improve the renal perfusion as well as the coronary perfusion.

Assisted Circulation↗
PubMed2003

Off-pump technique for Thoratec left ventricular assist device insertion.

We present a case of left ventricular assist device (Thoratec; Thoratec Laboratories Corp, Pleasanton, CA) insertion performed through a left thoracotomy without cardiopulmonary bypass in a patient with severe end-stage congestive heart failure with renal and respiratory dysfunction and a history of multiple cardiac operations.

Assisted Circulation↗
PubMed2003

New approach in treatment of acute cardiogenic shock requiring mechanical circulatory support.

In 12 patients with acute cardiogenic shock who required mechanical circulatory support a short-term Abiomed BVS 5000 extracorporeal assist device was implanted using the inflow and outflow cannulas of the BerlinHeart extracorporeal assist device. In 7 patients suitable for long-term support the Abiomed pumps were later exchanged for BerlinHeart pumps. This approach avoids the risks associated with repeat sternotomy and use of cardiopulmonary bypass and decreases the total costs of patient care.

Acute Disease↗