Assuntos
Infarto do Miocárdio/fisiopatologia , Angiografia , Animais , Pressão Sanguínea , Artéria Braquial/cirurgia , Vasos Coronários/cirurgia , Cães , Eletrocardiografia , Artéria Femoral/cirurgia , Fluoroscopia , Infarto do Miocárdio/mortalidade , Fotomicrografia , Plásticos , Fibrilação Ventricular/etiologiaAssuntos
Circulação Sanguínea , Circulação Extracorpórea , Infarto do Miocárdio , Pulso Arterial , Animais , Cães , Eletrocardiografia , Hemodinâmica , Humanos , Consumo de Oxigênio , ChoqueAssuntos
Aorta/fisiologia , Circulação Sanguínea , Tronco Braquiocefálico/fisiologia , Hemodinâmica , Pulso Arterial , Animais , Velocidade do Fluxo Sanguíneo , Pressão Sanguínea , Débito Cardíaco , Artérias Carótidas/fisiologia , Circulação Colateral , Cães , Circulação Extracorpórea/instrumentação , Resistência VascularAssuntos
Circulação Assistida/instrumentação , Idoso , Animais , Artérias , Circulação Sanguínea , Pressão Sanguínea , Débito Cardíaco , Cães , Insuficiência Cardíaca/terapia , Hemodinâmica , Humanos , Masculino , Métodos , Pessoa de Meia-Idade , Infarto do Miocárdio/terapia , Perfusão , Artéria Pulmonar , Choque/terapia , VeiasAssuntos
Circulação Assistida/métodos , Idoso , Arritmias Cardíacas/mortalidade , Pressão Sanguínea , Boston , Débito Cardíaco , Sistema Cardiovascular/fisiopatologia , Circulação Coronária , Feminino , Bloqueio Cardíaco/mortalidade , Humanos , Masculino , Pessoa de Meia-Idade , Miocárdio/metabolismo , Consumo de Oxigênio , Choque Cardiogênico/metabolismo , Choque Cardiogênico/fisiopatologia , Choque Cardiogênico/terapia , Fatores de TempoRESUMO
An inhomogeneous linear one-dimensional mathematical model is constructed as a conceptual approach to the study of the effects of External Counterpulsation (ECP) on the pressure and flow at the root of the aorta. The optimal operation of ECP is defined by two conditions: (1) minimization of the mean systolic pressure; and (b) maximization of the ratio of diastolic area over systolic area under the total pressure curve. The phase shift of the external pressure is determined so as to satisfy these two requirements. It is demonstrated within our approximation that with a given magnitude of external pressure, the phase shifts that satisfy these two requirements are the same. These phase shifts are linear functions of the systolic fraction of the total cardiac period, and depend on the time for the external wave to travel from the site of application up the vascular bed to the root of the aorta, plus the reflection contributions. Even though these results are derived from a simple model far from the complexity of the actual vasculature, the basic concepts would remain valid even if more complex mathematical treatments would have been used.
Assuntos
Circulação Assistida , Circulação Coronária , Modelos Biológicos , Aorta , Pressão Sanguínea , MatemáticaRESUMO
Assisted circulation techniques are an outgrowth of extracorporeal pump oxygenator systems developed in the mid 1950s. But the differences in physiology of total perfusions and of parital perfusions for assisting circulation delayed the clinical application of the intra-aortic balloon. The problems and risks in providing circulation assistance and the approaches used to overcome them are discussed. The various counterpulsation techniques are described and data presented to demonstrate the increased survival in patients with myocardial infarction and cardiogenic shock.
Assuntos
Circulação Assistida , Circulação Assistida/história , Circulação Assistida/métodos , Coração/fisiologia , Coração Artificial , Hemodinâmica , História do Século XX , Humanos , Pulmão/fisiologia , Miocárdio/metabolismo , Consumo de Oxigênio , Choque Cardiogênico/terapiaRESUMO
A pressure system externally applied to the limbs of a patient has been proven effective in assisting circulation in animal and clinical studies. In this study a nonlinear mathematical model of the cardiovascular system is utilized to determine the effectiveness of high-frequency components in the external pressure waveform. The development of the model, the method of analysis, and the results acquired with the model are presented in this report, demonstrating its suitability for the study of external counterpulsation.
Assuntos
Circulação Assistida/métodos , Fenômenos Fisiológicos Cardiovasculares , Modelos Biológicos , Animais , Circulação Assistida/instrumentação , Pressão Sanguínea , Cães , Hemodinâmica , Humanos , MatemáticaRESUMO
A summary of the work in synchronous assisted circulation undertaken at the Tufts-New England Medical Center Hospitals for the past year is presented.Counterpulsation, introduced in 1958, reduces myocardial oxygen consumption and increases coronary flow. It was applied to seven patients with terminal cardiogenic shock: one patient survived and three showed temporary improvement.The synchronous external assist makes possible control of the blood volume distribution, increases the cardiac output and decreases the pressure work of the left ventricle. The procedure does not require cannulation of the vascular system and is atraumatic.The same concept has been applied to the right ventricle using synchronous respiration.An "in-series" subcutaneously exteriorized prosthetic left ventricle, capable of long-term left ventricular assist, is under development. The device can atrialize the left ventricle. It requires no intracorporeal source of energy.This program offers hope for the development of effective temporary and long-term circulatory-assist procedures.