RESUMO
In right ventricular failure (RVF) a decrease of right ventricular afterload and improvement of left atrial filling could be achieved by a pulmonary artery-left atrial (PA)-shunt. To avoid cyanosis, artificial oxygenation is necessary. In 11 pigs a PA-shunt was created. An interventional lung assist device (ILA) was installed from the femoral artery to vein in 5 pigs (serial in relation to native lung: Group I) and into the PA-shunt in 6 pigs (parallel: Group II). RVF was induced by pulmonary artery banding. Right ventricular performance was determined by pulse contour analysis, pressure - and flow measurements. In both groups a stable RVF was generated. In Group I cardiac output trended to increase but neither right ventricular filling pressures nor arterial pressure changed significantly. The PaO2 decreased significantly. In Group II cardiac output and arterial pressure increased significantly under a shunt flow of 2.3- 2.6 l/min and the animals recovered from cardiogenic shock. In conclusion a PA-shunt with a parallel lung assist can effectively reverse the deleterious effects of RVF.
Assuntos
Procedimentos Cirúrgicos Cardíacos/métodos , Disfunção Ventricular Direita/cirurgia , Animais , Órgãos Artificiais , Pressão Sanguínea , Débito Cardíaco , Modelos Animais de Doenças , Feminino , Átrios do Coração/cirurgia , Insuficiência Cardíaca/cirurgia , Coração Auxiliar , Pulmão/cirurgia , Artéria Pulmonar/cirurgia , Troca Gasosa Pulmonar , Sus scrofa , Disfunção Ventricular Direita/fisiopatologiaRESUMO
BACKGROUND: In multifocal flicker stimulation, each step of the M-sequence consists of four consecutive flashes with a frequency of 30 Hz. The resulting amplitudes can be calculated by means of a discrete fourier transformation (DFT). With this method, amplitudes can be calculated without having to localise peaks and troughs and set cursors. The purpose of this study is to compare the re-test stability of this method to conventional mfERG stimulation. METHODS: We examined 27 healthy subjects using a RETI-scan device (Roland Consult, Wiesbaden). We used 61 hexagons within a 30 deg. visual field. We compared the classic first order kernel (FOK) stimulation with the multifocal 30 Hz Flicker (mfFlicker-ERG) stimulation. Repeatability was calculated using coefficients of variation. RESULTS: Both methods had coefficients of 15% for the sum P1-amplitude and the DFT results, respectively. The amplitudes calculated by flicker and DFT were approximately 25% smaller than the FOK amplitudes. CONCLUSIONS: This study showed no difference of re-test repeatability between the mfFlicker-ERG and the conventional first order kernel method. Since the mfFlicker-ERG method does not require a definition of peaks and troughs in order to calculate the amplitudes, we believe that a common source of error is eradicated, especially when dealing with distorted or atypical curves.