ABSTRACT
Objective To find a new method for evaluating the left ventricular relaxation time constant Tau with aortic regurgitation by continuous wave Doppler.Methods Twelve Beagle dogs were included in the study.The dog aortic regurgitation model was produced under ultrasound guiding by carotid artery puncture.Aortic pressure was measured by pressure catheter and left ventricular pressure was measured by Millar catheter which was introduced into the left ventricular through cardiac apex.Then microspheres were injected into the left coronary artery under the guidance of ultrasound to induce acute ischemic left ventricular dysfunction,when left ventricular end-diastolic pressure increased more than 5 mmHg (1 mmHg=0.133 kPa).Dobutamine or esmolol was infused to alter left ventricular function.Aortic regurgitation velocity spectrum was recorded by the continuous-wave Doppler echocardiography in different hemodynamic status.At the same time,left ventricular pressure,dp/dt,aortic pressure and continuous ECG tracing were displayed on the multi-channel physiological recorder.Measurement was recorded of-dp/dtmax in the dp/dt tracings and the pressure at the time of-dp/dtmax in the left ventricular pressure tracings.Tau =-P/(dp/dtmax),Tau was the catheter-derived time constant (Taucatheter).Aortic regurgitation spectrum of original audio data was post-processed with MATLAB mathematical software.The spectral lines refresh time of about 300 μs was chosen to form a new Doppler spectrum.Three points:(t1,1 m/s),(t2,2 m/s) and (t3,3 m/s) were selected in aortic regurgitation velocity spectrum and tl,t2 and t3 was put into the corresponding Tau formula:Tau=(t2-t1)/ln[(ADP-C-4)/(ADP-C-16)],Tau=(t3-t1)/ln[(ADP-C-4)/(ADP-C-36)].Tau was the aortic regurgitant time constant (Tauultrasound).The difference between Taucatheter and Tauultrasound was compared by paired t test.The correlation between Taucatheter and Tauultrasound was analyzed by Pearson correlation analysis.Results Twelve dogs were successfully produced aortic regurgitation model.Two dogs died of ventricular fibrillation during the procedure of acute ischemic left ventricular diastolic dysfunction.The range of the Taucatheter was between 27.12 ms and 86.88 ms with an average of (48.973± 14.667) ms;the range of the Tauultrasound was between 28.13 ms and 90.18 ms with an average of (51.236± 15.146) ms.The difference was not statistically significant (t=1.841,P ＞ 0.05).Pearson correlation analysis showed that Taucatheter was positively correlated with Tatultrasound (r=0.89,P=0.000).Conclusion Choosing three points:(t1,1 m/s),(t2,2 m/s) and (t3,3 m/s) in aortic regurgitant velocity spectrum and putting into the corresponding formula,we can calculate Tau,which had a good correlation with the catheter-derived Tau.
ABSTRACT
Objective To explore the new method for noninvasively measuring the time constant of left ventricular relaxation (Tau) in animals with mitral regurgitation by continuous-wave Doppler.Methods The acute ischaemic left diastolic heart failure with mitral regurgitation was produced in 9 dogs.Dobutamine hydrochloride or esmolol hydrochloride had been applied to change the hemodynamic states.In different hemodynamic states,left ventricular pressures,left atrial pressures,curves of dP/dt and continuous-wave mitral regurgitant spectra were synchronously recorded.Doppler spectra were laterly processed through Matlab workstation.Paired t-test was used to compare the difference between Tau-catheter (Tau-c) and Tau-doppler ultrasound (Tau-d),and the correlation between Tau-c and Tau-d was analyzed by Pearson correlation analysis.Results Thirty-nine hemodynamic status had been obtained in 9 dogs.Tau-c was 21.03-78.45 ms and the average was (48.76± 17.60) ms.Tau-d was 21.24-94.60 ms and the average was (49.33 ± 18.79) ms.There was no significant difference (t=0.353,P=0.726) between Tau-d and Tau-c.The correlation analysis between Tau-d and Tau-c suggested a strong positive relationship with the correlation coefficient (r=0.85,P ＜ 0.001).Conclusions The dog aortic regurgitation model under ultrasound guidance is less traumatic.The method of inducing left ventricular diastolic dysfunction by repeatedly injecting microspheres into the left coronary sinus is safe and reliable.Choosing three points (t1,1 m/s;t2,2 m/s;t3,3 m/s) in aortic regurgitant velocity spectrum and putting them into the corresponding formula,we can obtain Tau,which had a good correlation with the catheter-derived Tau.
ABSTRACT
Objective To investigate the effect of patient positioning on the Duplex ultrasound evaluation of great saphenous vein reflux elicited by the pneumatic cuff method. Methods FFifty great saphenous veins (GSV) with relfux (relfux group) and iffteen with no prior history of venous disease (healthy group) were examined by duplex scanning in the supine, 20 degrees reverse-trendelenburg (RT-20), 40 degrees reverse-trendelenburg (RT-40) and standing position. Each GSV was assessed for relfux at three venous sites:two centimeter below the sapheno-femoral junction (SFJ), the greater saphenous vein in the mid thigh (MGV) and the greater saphenous vein in the upper calf (CGV). Pneumatic cuff compression pressure of conifned 100 mmHg (1 mmHg=0.133 kPa) was used onto the calf to elicit relfux. The incidence of positive venous relfux was calculated. The statistical differences of the peak relfux velocity and duration of relfux in four positions were analyzed. Results TThe relfux elicited in the standing position was set as the gold standard. In healthy group, there was no false positive results of relfux in supine, RT-20 and RT-40 positions. In relfux group, false negative results were found at all venous sites when limbs were examined in supine position [false negative rate:59%(19/32), 22%(11/50), 24%(12/50)]. At RT-20 and RT-40 positions, the incidence of venous relfux reached 100% at MGV and CGV, and false negative cases were only detected at SFJ [false negative rate:12%(4/32), 12%(4/32)]. The relfux time in standing, supine, RT-20 and RT-40 positions were (7.75±3.23) s, (5.27±3.66) s, (8.67±3.72) s, (8.55±3.93) s respectively. There were signiifcant differences among different positions in reflux time (F=56.9, P 0.05), except for supine position (q=4.11, P<0.01). Peak relfux velocity in standing, supine, RT-20 and RT-40 positions were (55.26±22.24) cm/s, (22.87±12.03) cm/s, (38.46±16.30) cm/s, (45.13±19.21) cm/s respectively. There were also signiifcant differences among different positions in peak relfux velocity (F=13.7, P<0.01). Comparing the supine, RT-20 and RT-40 positions with standing position, differences of the peak relfux velocity between them were all statistically signiifcant (q=12.71, 6.59, 3.98 respectively, all P<0.01). Conclusions When GSV reflux was examined by pneumatic cuff compression, false negative rate was higher in the supine position. RT-20 and RT-40 position were effective to detect GSV relfux, espically for GSV at mid-thigh and upper calf.
ABSTRACT
Objective To evaluate the diagnostic value of ultrasound-guided pleural biopsy combined with thoracic biochemical detections in malignant and tuberculous pleural effusions. Methods Sixty-four patients with moderate or large pleural effusions and pleural thickening received the ultrasound-guided diagnostic pleural biopsy. All patients had chest CT enhancement scans to find out the suspicious pleural thickening preoperatively, facilitating the selection of puncture sites by ultrasound. Pleural tissue samples were sent for pathological examinations immediately. After successful achievements of pleural biopsy, ultrasound-guided aspiration or drainage was performed to alleviate symptoms, more importantly, to get pleural effusions for biochemical analysis. Biological results including carcinoembryonic antigen(CEA), CA125, CYFRA21 and lactate dehydrogenase(LDH) in malignant and tuberculous effusions were analyzed by group design t tests. The positive rates of CEA, CA125, CYFRA21, LDH in malignant and tuberculous effusions were compared by chi square tests. Results Pleural tissues in all cases were got by one pleural biopsy procedure. The strategy of pleural biopsy we used in this study had a successful rate reaching 100%(64/64), and 73% (46/64) patients had a definitive diagnosis as malignant or tuberculous effusion. Twenty-seven cases were diagnosed as malignant effusions and thirty-seven cases as tuberculous effusions based on the deifnitive clinical diagnosis. The positive rates of CEA, CA125, CYFRA21, LDH in malignant effusions were 100%(27/27), 100%(27/27), 100%(27/27), 89%(24/27) respectively, and 0%(0/37), 84%(31/37), 78%(29/37), 76%(28/37) respectively in tuberculous effusions. The positive rate of CEA between malignant and tuberculous effusions differed signiifcantly (χ2=64.0, P < 0.01), so did CA125 (χ2=3.1, P < 0.01) and CYFRA21(χ2=4.8, P<0.01). The average levels of CEA, CA125, CYFRA21, LDH in pleural effusion were (727.1±658.8)μg/L, (795.2±1249.6)×103 U/L, (296.2±320.7)μg/L, (1077.9±1058.5) U/L respectively, and (1.7±1.1)μg/L, (336.3±208.6)×103 U/L, (20.7±14.9)μg/L, (309.2±182.7) U/L in tuberculous effusions.There were signiifcant differences in CEA, CYFRA21 and LDH concentrations among malignant and tuberculous effusions (t=45.1, 27.4, 18.8 respectively, all P<0.01). Conclusion Ultrasound-guided pleural biopsy combined with CEA, CYFRA21 and LDH in pleural effusions had an important value in the etiological diagnosis of pleural effusions, while CA125 showed little value in the differential diagnosis.