The Research On The Influences Of Cardiac Motion And Respiration On The Determination Of Doppler Flow Parameters

1. The influence of cardiac motion on the velocity-time integrals of Doppler flow spectrum: in vitro model study1.1 ObjectiveTo design and make cardiac base motion simulated instrument by ourselves , and to establish simulated experimental model to observe the influence of simulated cardiac motion on the measurements of Doppler spectrum velocity- time integral (VTI) of simulated blood flow at the cardiac base.1.2 Methods1. 2.1 The fabrication of experimental instrumentTest I We simulated cardiac base motion by using Heart-Motion Simulator Model TD-3 (HMSTD-3) made by ourselves and blood flow simulator which was composed of pipeline plank, tubing and pulsatile pump. The pulsatile pump could make the simulated blood flow through the chamber to be of pulsatile so that it could satisfy the demand offrequence and amplitude of simulated blood flow in vitro. 6% starch-Glycer in water slurry was driven by the pulsatile pump through the tubing to simulate the blood flow in the simulated heart, and the tubing was cyclically moved by HMSTD-3. The transducer was stationary.Test II The echotransducer was fixed on the slide board of HMSTD-3 so that the transducer and the simulated heart became one part(transducer + simulated heart) and moved together. 1. 2. 2 Index observationTest I Acuson' s Sequoia 512 and Acuson 128 XP/10ultrasonographic systems were used in this study to record the Doppler spectrum of simulated heart and simulated blood flow that moved separately , synchronously or unsynchronously, and to quantitatively assess their relations and the influence of simulated heart motion on the determation of Doppler spectrum VTI of the simulated blood flow.Test II To observe and note the feature of Dopplerspectrum of simulated blood flow when the transducer + simulated heart and simulated blood flow moved synchronously or unsynchronously respectively . 1.3 ResultsTest I In the model in vitro, the alterations in the motion of the tubing resulted in apparent changes in the measured maximal velocity and VTI of the fluid. The Doppler spectrum of the combined motion of the tubing and the fluidwas the algebraic sum of their Doppler signals. The velocity and frequency of Doppler spectrum generated by simulated heart motion did not change.Test II When transducer + simulated heart and simulated blood flow moved together, the shape, Vmax and VTI were the same as those when simulated blood flow moved along whether their motions were in phase or not. 1.4 ConclusionsThe motion of the simulated heart has a great influence on the form and the value of simulated Doppler blood flow spectrum VTI. The Doppler flow tracing which recorded by echocardiography was already modulated according to the VTI adding or subtracting by the simulated heart motion. The VTI of simulated heart accounted for 25% of the VTI of simulated Doppler blood flow spectrum and this effect should be considered when blood flow volume is measured by using Doppler' s methods.2. Influence of cardiac motion on the measurement of Doppler flow spectrum through the valve: in vivo model study 2.1 ObjectiveTo quantitatively observe the changes of blood flow VTI through the aortic valve with the transducer moving in the same direction with the motion of cardiac base, and so as to help the correction of the way of measuring the stroke volume by Doppler methods. 2. 2 Methods 2. 2.1 The fabrication of experiment instrumentTo change the HMSTD -3 mode simulator into the HMSTD-4 mode cardiac base motion simulator model in vitro by fixing the transducer on the sliding board of the HMSTD -3 and to make the direction of sonar beam parallel to the direction of blood flow of left ventricular outflow tract. The frequency and amplitude of HMSTD-4 mode simulator were the same as those of the human subjects' cardiac base motion. HMSTD-4 simulator was used to move the transducer with a water-balloon so that the transducer is relative stable to the sample volume at the aortic annulus when aortic Doppler flow at apex-five chamber view was recorded in su...