Objective To reveal the exact mechanical principle of the respiration-driven variation of cardiac function by observing the effect of respiratory intrathoracic pressure change (RIPC) on the mechanical models using echocardiography.Methods Model 1 was designed to observe the influence of RIPC on systemic and pulmonary venous return systems (SVR and PVR) respectively.Model 2,as an equivalent mechanical model of septal swing,was used to study the influence of RIPC on the motion of the interventricular septum (IVS).Results Model 1 demonstrated that the simulated RIPC had totally different influences on the simulated SVR and PVR.It increased the volume of the simulated right ventricle when the internal pressure was kept constant (8.16 cm H2O),while it had the opposite effect on PVR.Model 2demonstrated that there was a corresponding relationship between RIPC and the position of the simulated IVS which might be called pressure-position relationship.Conclusions The different anatomical arrangement of the two venous return systems leads to a different effect of RIPC on right and left ventricles,and thus generates a pressure gradient across IVS that tends to shift IVS left-and right-wards with respiration.The swing of the IVS changes the short axis diameters of the ventricles,thus their fillings and then their functions reciprocally.

Objective To investigate the affecting factors of interventricular septum (IVS) swing by study of the mechanical model of the respiration-driven variation of cardiac function using echocardiography.Methods In present study,the equivalent mechanical model of septal swing in previous study was used.By changing the end-diastolic pressure difference between the simulated right and left ventricles and simulated intrapericardial pressure,the subsequent influences on IVS swing using echocardiography were observed.Results Under the rhythmic respiratory intrathoracic pressure change(RIPC)(0--4 mm Hg,1 mm Hg =0.133 kPa),the swing amplitude of simulated IVS increased with decrease of the simulated end-diastolic pressure difference between the simulated right and left ventricles (2.2-17.6 mm).With increasing of the simulated intrapericardial pressure,the simulated right ventricle and left ventricle collapsed in succession,the swing amplitude of simulated IVS also increased to a maximal amplitude of 22.4 mm.Conclusions The affecting factors of IVS swing including the magnitude of RIPC,the end-diastolic pressure difference between the two ventricles and the intrapericardial pressure.

Objective To explore the mechanism of intrathoracic pressure(ITP) influncing cardiac function and facilitate noninvasive determination of ventricular pressure theoretically.Methods With Valsalva and Mueller maneuver,two-dimension images of standard long axis views and the cross-sectional views were recorded in 20 volunteers,aged from 18 to 45 years,at the specific ITP levels(including-20 mmHg、-10 mmHg、0 mmHg、+ 10 mmHg and + 20 mmHg).The subjects were instructed to mantain for at least 10 s,and three successive measurements were recorded and averaged.The stroke volume(SV) and radius of curvature(R) were obtained from further off-line analysis.Results With the ITP maintaining at -20 mmHg,-10 mmHg,0 mmHg(end expiration),+ 10 mmHg and + 20 mmHg respectively,the corresponding radiuses of curvature were (2.35 ±0.24)cm,(2.25 ± 0.23)cm,(2.14 ± 0.21)cm,(2.02 ± 0.21) cm,(1.93 ± 0.19) cm,there were statistically significances between two groups (P =0.006,0.031,0.005 and ＜0.001,respectively].When the ITP were at 0 mmHg(end expiration),+ 10 mmHg and + 20 mmHg,the stroke volume were (71.54±8.81)ml,(73.20±9.52)ml and (78.81± 14.61)ml (P =0.674,0.135).When the intrathoracic pressure decreased from 0 mmHg to-20 mmHg,the stroke volume were (78.81±14.61)ml,(68.28 ±9.28)ml and (59.69±7.52)ml(P =0.029,0.037).Conclusions The ITP has different effects on the two ventricles,and subsequently generates a pressure gradient across the IVS which can alter its shape and position at end-diastole.With the IVS shifting,the preload and filling function of left ventricle gets changed acorrding to the Frank Starling principle.

Objective To propose an accurate method of noninvasive determination of central venous pressure(CVP ) by locating the central point of right atrium (RA ) using echocardiography .Methods Through the 3D reconstruction ,the accurate positions of RA of 30 patients who had been examined by multislice 3‐dimensional computed tomography for chest imaging were recorded .Based on solid geometric principles ,the central point in RA was located by echocardiography and then compared with CT‐location point .The accuracy and feasibility were assessed by absolute distance (Da) ,vertical distance (Dv) and the whole time of location (T) between the two points .Results Mean Da ,Dv and T of the whole subjects were 07.6cm(95% CI:06.2to08.1cm),01.6cm(95% CI:-00.2to03.4cm),and438.0s(95% CI:400.1to 47 4.0 s) ,respectively .Conclusions The echocardiographic method on the basis of solid geometry proposed in this study could be used to locate the central point in RA accurately and simply .Thus it would be helpful to improve the accuracy of noninvasive determination of central venous pressure .

Objective To determine the central venous pressure (CVP) noninvasively based on hemodynamics principles using ultrasound location of the collapse point of the internal jugular vein.Methods Forty patients were enrolled in this study.The collapse point of the internal jugular vein was located and marked by a linear transducer,the body mark of right atrium was marked on the right lateral wall of the chest.The noninvasive CVP was calculated according to the vertical distance between those two points.The invasive CVP determination by central venous catheter was also carried out on all the patients.Correlation analysis was used to compare the invasive and noninvasive methods.With invasive determination of CVP as the gold standard,the ROC curve of the noninvasive ultrasound method was sketched to explore the optimal cut-off points.Results The correlation analysis reveal high positive correlation between CVPs determined by ultrasound imaging and central venous catheter (r =0.906,P ＜0.01).By the ROC curve test,fluid column height of 10.75 cm by ultrasound method was determined as the cut-off point,with the sensitivity and specificity of diagnosing elevation of CVP being 88.9％ and 93.5 ％ respectively.The corresponding area under the curve was 0.971.Conclusions Ultrasound imaging could be used to determine CVP noninvasively,which would be helpful in diagnosis of the circulating load of patients.

Objective To observe the peripheral arterial Doppler flow velocity curve changes and elucidate the blood flow characteristics by adding extra pressure on the limbs,and to provide evidence for better diagnosis of peripheral arterial diseases by ultrasound.Methods Color Doppler ultrasound instrument was used to record the brachial artery(BA),radial artery(RA),common femoral artery(CFA) and popliteal artery(POA) Doppler flow velocity curves both at rest and under different grades of distal and proximal limb pressuring in 40 randomly selected healthy adults.The peak systolic and early diastolic reverse flow velocity(PSV,PRV) and the resistance index (RI) were measured and analyzed.Results Three-phase waveform was seen at rest.Significant changes were noticed in PRV and RI under distal pressuring,while no significant difference was seen in PSV between groups.Conclusions Normal peripheral arteries show pulsed step-by-step blood flow pattern along with the cardiac cycles.Peripheral arterial Doppler flow curves changes regularly with limb grading pressuring.

Objective To decompose left ventricular contractile motions and analyze the corresponding contributions of different components to left ventricular systolic function . Methods Sixty‐nine healthy adults with normal left ventricular eject fraction ( LVEF ) were recruited . T wo‐dimensional speckle tracking echocardiography was performed by GE Vivid E 9 system ,and strain parameters were analyzed by EchoPac software . Correlation and multiple stepwise regression analysis were performed to analyze the contributions of different components of myocardial motion to left ventricular contraction . Results Global longitudinal strain ( GLS) ,global circumferential strain ( GCS ) ,global radial strain ( GRS ) and twist were all significantly correlated with LVEF ( r ＝ －0 .668 , P ＜0 .001 ; r ＝ －0 .552 , P ＜0 .001 ;r ＝0 .335 , P ＝0 .006 ; r ＝0 .428 , P ＜0 .001) . Significant correlations were found between all the strain parameters ,except for GRS and twist . M ultiple stepwise regression adjusted for sex ,and age showed that the uni‐contributions of GLS , GCS , GRS and twist to LVEF were 21 .3% , 13 .0% , 7 .5% , 8 .8% , respectively . However ,with all strain parameters in the general regression model ,only GLS and twist were still significantly related with LVEF ( R2 ＝0 .566 , P ＜0 .001) . Conclusions T he contributions of various components of myocardial motion to left ventricular contraction in healthy adults are different . Although every component is significantly related with LVEF ,the longitudinal and twist motion are most important in the integrated view .

Objective:To reveal the diurnal variation characteristics of the exercise adaptability of cardiac function in healthy men of different ages by the analysis of echocardiographic parameter changes before and after exercise intervention using the left ventricular pressure-strain loop techniques.Methods:A prospective control design was used to collect 193 healthy male volunteers from October 2022 to July 2023 in Tangdu Hospital, 101 in the young group [(26±5) years old], and 92 in the middle-aged group [(50±4) years old]. The heart rate, blood pressure and routine echocardiographic parameters were collected at rest and after exercise stress (3-minute step test) at 7∶00 a.m.and 10∶00 p.m., respectively. The heart rate, blood pressure cardiac output, and echocardiographic parameters [anteroposterior diameter of left atrium (LAD), ratio of peak early diastolic flow velocity to late diastolic peak flow velocity of mitral valve (E/A), left ventricular ejection fraction (LVEF), left ventricular end diastolic diameter (LVEDD), left ventricular end systolic diameter (LVEDS)] were then determined. The parameters of myocardial work including left ventricular longitudinal strain (GLS), global work index (GWI), global work efficiency (GWE), global constructive work (GCW) and global wasted work (GWW) were obtained by left ventricular pressure-strain loop technique. The differences of the parameters above between before and after step test, morning and night, young group and middle-aged group were compared.Results:The heart rate, blood pressure and cardiac output of young and middle-aged healthy men increased significantly in the morning and night step test (all P<0.05), GLS, GWI, GCW and GWW were significantly higher than those in resting state (all P<0.05), and GWE was significantly lower than that in resting state ( P<0.05). The change rates of heart rate, cardiac output, GLS, GWI and GCW in the early morning were significantly higher than those at night (all P<0.05), while the change rates of blood pressure and GWE in each group were significantly lower than those at night ( P<0.05). The change rates of heart rate, systolic blood pressure, GLS and GWI in the middle-aged group were significantly higher than those in the young group in the morning and night (all P<0.05), while the change rate of diastolic blood pressure at night was significantly higher than that in the young group ( P<0.05), but there was no significant difference in the morning ( P>0.05). Conclusions:The cardiac adaptability of healthy men has obvious circadian rhythm, characterized by being of low in the morning and high in the evening. Age mainly affects the cardiac adaptability in the morning. The response to low-intensity load stimulation increases with aging, indicating the decrease of morning cardiac adaptability.

Objective:To study the prognostic value of left atrial strain in diastolic function response by treadmill exercise stress echocardiography.Methods:During May 2018 to February 2019, 64 patients underwent treadmill exercise stress echocardiography for diastolic function evaluation in Tangdu Hospital, Air Force Medical University, were recruited.Patients were categorized into diastolic stress test negative group (pre-stress E/e′ <14 & post-stress E/e′<14) (DST- group), and diastolic stress test positive group (pre-stress E/e′ <14 & post-stress E/e′>14) (DST+ group). Patients′ characteristics of the stress test, left ventricular diameter, left atrial volume index, systolic and diastolic function, and left atrial strain parameters were compared between these two groups. ROC analyses were performed based on the echocardiographic parameters with significant group differences ( P<0.01) to determine the predictive values for diastolic stress test response. Results:The pre-stress E/e′ and left atrial strain parameters were significantly differently between DST- and DST+ group. The DST- showed significantly lower E/e′ (8.20±1.27 vs 10.32±1.33, P<0.01), but higher left atrial strains than DST+ group[reservoir function(33.7±5.7)% vs (26.5±5.5)%, P<0.01; conduit function(16.8±4.0)% vs (11.8±3.4)%, P<0.01; pump function(16.9±5.7)% vs (14.7±5.5)%, P<0.05]. The left atrial reservoir function, conduit function and pre-stress E/e′ could predict the diastolic stress test response, the areas under ROC curve were 0.81 ( P<0.01), 0.62 ( P=0.04) and 0.71 ( P<0.01). Conclusions:The left atrial strain parameters under resting condition could predict the diastolic stress test response. It may serve as an alternative method of exercise stress echocardiography for diastolic function evaluation.

Objective To investigate the value of S-Detect classification in differential diagnosis of breast mass . Methods The data of forty-seven patients with breast mass lesions ( n=61) from our hospital during January to December in 2016 were retrospectively analyzed . Both the man-made BI-RADS classification ( identified by three different specialist physicians with 2 ,5 and 7 years of experience , respectively) and computer S-Detect classification were performed . The sensitivity ,specificity ,accuracy , positive predictive value and negative predictive value of the man-made BI-RADS classification and S-Detect classification of the benign or malignant diagnosis of breast lumps were calculated . The ROC curve was further plotted ,and the area under the curve ( AUC) of each group was compared ,respectively . Results Sixty-one breast mass lesions were confirmed 36 benign lesions and 25 malignant lesions by pathological biopsy . The sensitivity ,specificity and accuracy of man-made BI-RADS classification were as follows:2-year experience physicians 69 .4％ ,72 .0％ and 70 .5％ ;5-year experience physicians:64 .0％ ,92 .0％ and 75 .4％ ;7-year experience physicians:69 .4％ , 92 .0％ and 78 .7％ . The diagnostic sensitivity , specificity , and accuracy of S-Detect classification were 80 .6％ ,96 .0％ and 86 .9％ . The specificity ,accuracy and positive predictive value of S-Detect classification were significantly higher than those of 2-year experience physicians by BI-RADS classification ( P <0 .05) . The area under the ROC curve of each group was 0 .729 ,0 .786 and 0 .801 for 2 , 5 and 7-year experience physicians , respectively , and 0 .917 for S-Detect classification . Conclusions Compared with the man-made BI-RADS classification ,S-Detect classification has advantages in diagnosis of the benign or malignant of breast mass and is helpful to improve the accuracy of diagnosis , especially for junior physicians .