| Objectives1. To observe the effects of quiet respiration on left to right shunt of the atrial septal defect (ASD) patients and its regularity, and to verify the new proposal of the mechanism of respiration effects on hemodynamics. To investigate the potential significance of the velocity change of the left to right shunt during the quiet respiratory on evaluating the left ventricular diastolic function. Meanwhile, establishes mechanical foundation for the ASD patients to have a better choice for their occluders. 2. To observe the effects of quiet respiration on left to right shunt of the ventricular septal defect (VSD) patients and its regularity, and to verify the new proposal of the mechanism of respiration effects on hemodynamics. And also offers the theoretical foundation for the application of the new measurement of the cardiac function. 3. To observe the effects of quiet respiration on mitral Doppler flow and to verify the new hypothesis illustrating the mechanism of respiration effects on hemodynamics.Methods1. Pulsed-wave Doppler spectra of the velocity of the left to right shunt which is on atrial's level were recorded by Acuson Sequoia 512 in 32 ASD patients. Electrocardiogram and respiratory tracing by a nasal thermistor were recorded simultaneously.2. Pulsed-wave Doppler spectra of the velocity of the left to right shunt which is on ventricular's level were recorded by color Doppler ultrasonograph in 28 VSD patients. Electrocardiogram and respiratory tracing by a nasal thermistor were recorded simultaneously.3. Pulsed-wave Doppler spectra of mitral flow were recorded with Sequoia 512 in 10 ASD patients and 20 VSD patients. Electrocardiogram and respiratory tracing were recorded synchronously. E and A waves of mitral flow were measured and the velocity-time integrals (VTI) were calculated by the software. The mitral flow velocity and VTI during inspiration and expiration were averaged for five continuous respiratory cycles respectively. The ratios of velocity and VTI of E to A of mitral flow during inspiration and expiration were calculated respectively.Results1.The blood velocity of the shunt on atrial's level is lower in inspiration than in expiration during quiet respiration in ASD patients(inspiratory phase,110.15±22.32cm/s;expiratory phase123.40±26.53cm/s,P <0.01)2. The blood velocity of the shunt on ventricular's level is lower in inspiration than that in expiration during quiet respiration in VSD patients, which was more obvious at end-inspiration and end-expiration. [end -inspiration(435.59±84.62)cm/s; end -expiration(473.55±85.64)cm/s,P <0.01]. 3. In all the 10 ASD patients, the Doppler flow velocity and VTI of E wave were increased remarkably from inspiration to expiration(81.45±20.38 cm/s±20.38 cm/s,88.65 cm/s±21.34 cm/s,P<0.0001;14.87±5.98 cm,16.38±5.19 cm,P<0.0001);The Doppler flow velocity and VTI of A wave were also increased remarkably from inspiration to expiration(57.88 cm/s±9.56cm/s,61.43 cm/s±11.27 cm/s,P<0.0001; 10.86±4.57 cm,12.48±4.15 cm,P<0.0001).The ratios of the velocity and VTI of E to A during inspiration were lower than those during expiration(1.63±0.58,1.74±0.53,P<0.0001;1.54±0.43,1.65±0.47,P<0.0001). In all the 20 VSD patients ,the Doppler flow velocity and VTI of E wave were increased remarkably from inspiration to expiration(89.37±16.38 cm/s,96.42±18.34 cm/s,P<0.0001;16.54±4.32 cm,18.81±5.39 cm,P<0.0001);The Doppler flow velocity and VTI of A wave were also increased remarkably from inspiration to expiration(67.94±10.56 cm/s,73.82±12.2 cm/s,P<0.0001;14.74±3.27 cm,15.69±4.22 cm,P<0.0001).The ratios of the velocity and VTI of E to A during inspiration were lower than those during expiration(1.76±0.64,1.82±0.69,P<0.0001;1.22±0.32,1.31±0.39,P<0.0001).Conclusion1.The velocity of the left to right shunt that is on the atrial's level of the patients with ASD changes along with the respiration phase, proving that the respiratory intrathoracic pressure change is the reason that causes the variation of the shunt velocity. It provides more evidence for the new hypothesis of the mechanism of respiration effects on cardiac function, and establishes mechanical foundation for helping the ASD patients have a better choice for the occluders.2.The velocity of the left to right shunt that is on the ventricular's level of the VSD changes along with the respiration phase, proving that the respiratory intrathoracic pressure change might be one of the reasons that causes the variation of the shunt velocity. This study provided more evidence for the new hypothesis of the mechanism of respiration effects on cardiac function. 3. The effects of quiet respiration on mitral Doppler flow were regular: The velocities and VTIs of E and A and the ratios of the velocity and VTI of E to A during inspiration were all lower than those during expiration. It would provide more information in evaluating left ventricular filling. This study further proved the accuracy of the new hypothesis of respiration effects on hemodynamics.
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