Acoustic cardiography to improve detection of coronary artery disease with stress testing

AIM:To assess if performance of 12-lead exercise tolerance testing(ETT) can be improved by simultaneous acoustic cardiography and to compare the diagnostic performances of electrocardiography(ECG) during ETT and acoustic cardiography for detection or exclusion of angiographically proven coronary artery disease(CAD).METHODS:We conducted an explorative study with retrospective data analysis using a convenience sample of consecutive patients(n = 59,mean age:62 years) from an outpatient clinic in Switzerland,who were referred for ETT by their general practitioner on suspicion of CAD,and in whom,coronary angiography was carried out.Measurements included sensitivity,specificity,likelihood ratios and receiver operating characteristic curves.A standard,symptom-limited,12-lead ECG exercise tolerance test was performed by independent persons with simultaneous acoustic cardiography and subsequent cardiac angiography for determination of significant CAD.RESULTS:Thirty-four of the 59 adult subjects(58%) had a final diagnosis of CAD by angiography,and in 25 subjects,CAD was excluded by angiography.Sensitivity/specificity of ST segment depression in the group was 29%/92%,whereas the most powerful acoustic cardiographic parameter was the strength of the fourth heart sound(S4),with corresponding sensitivity/specificity of 53%/92%.The disjunctive combination of the S4 and ST depression had sensitivity/specificity of 68%/84%.CONCLUSION:In this preliminary pilot study,the use of acoustic cardiography alone during ETT or disjunctively with ST depression has been shown to be a simple and convenient method for the detection of CAD,which was superior to ST depression on the standardized ECG.

Dynamic Characteristic Mechanism of Atrial Septal Defect Using Real-Time Three-Dimensional Echocardiography and Evaluation of Right Ventricular Functions

The dynamic characteristics of the area of the atrial septal defect（ASD） were evaluated using the technique of real-time three-dimensional echocardiography（RT 3DE）, the potential factors responsible for the dynamic characteristics of the area of ASD were observed, and the overall and local volume and functions of the patients with ASD were measured. RT 3DE was performed on the 27 normal controls and 28 patients with ASD. Based on the three-dimensional data workstations, the area of ASD was measured at P wave vertex, R wave vertex, T wave starting point, and T wave terminal point and in the T-P section. The right atrial volume in the same time phase of the cardiac cycle and the motion displacement distance of the tricuspid annulus in the corresponding period were measured. The measured value of the area of ASD was analyzed. The changes in the right atrial volume and the motion displacement distance of the tricuspid annulus in the normal control group and the ASD group were compared. The right ventricular ejection fractions in the normal control group and the ASD group were compared using the RT 3DE long-axis eight-plane（LA 8-plane） method. Real-time three-dimensional volume imaging was performed in the normal control group and ASD group（n=30）. The right ventricular inflow tract, outflow tract, cardiac apex muscular trabecula dilatation, end-systolic volume, overall dilatation, end-systolic volume, and appropriate local and overall ejection fractions in both two groups were measured with the four-dimensional right ventricular quantitative analysis method（4D RVQ） and compared. The overall right ventricular volume and the ejection fraction measured by the LA 8-plane method and 4D RVQ were subjected to a related analysis. Dynamic changes occurred to the area of ASD in the cardiac cycle. The rules for dynamic changes in the area of ASD and the rules for changes in the right atrial volume in the cardiac cycle were consistent. The maximum value of the changes in the right atrial volume occurred in the end-systolic period when the peak of the curve appeared. The minimum value of the changes occurred in the end-systolic period and was located at the lowest point of the volume variation curve. The area variation curve for ASD and the motion variation curve for the tricuspid annulus in the cardiac cycle were the same. The displacement of the tricuspid annulus exhibited directionality. The measured values of the area of ASD at P wave vertex, R wave vertex, T wave starting point, T wave terminal point and in the T-P section were properly correlated with the right atrial volume（P〈0.001）. The area of ASD and the motion displacement distance of the tricuspid annulus were negatively correlated（P〈0.05）. The right atrial volumes in the ASD group in the cardiac cycle in various time phases increased significantly as compared with those in the normal control group（P=0.0001）. The motion displacement distance of the tricuspid annulus decreased significantly in the ASD group as compared with that in the normal control group（P=0.043）. The right ventricular ejection fraction in the ASD group was lower than that in the normal control group（P=0.032）. The ejection fraction of the cardiac apex trabecula of the ASD patients was significantly lower than the ejection fractions of the right ventricular outflow tract and inflow tract and overall ejection fraction. The difference was statistically significant（P=0.005）. The right ventricular local and overall dilatation and end-systolic volumes in the ASD group increased significantly as compared with those in the normal control group（P=0.031）. The a RVEF and the overall ejection fraction decreased in the ASD group as compared with those in the normal control group（P=0.0005）. The dynamic changes in the area of ASD and the motion curves for the right atrial volume and tricuspid annulus have the same dynamic characteristics. RT 3DE can be used to accurately evaluate the local and overall volume and functions of the right ventricle. The local and overall volume loads of the right ventricle in the ASD patients increase significantly as compared with those of the normal people. The right ventricular cardiac apex and the overall systolic function decrease.

Frequency domain cardiography and radionuclide ventriculography for evaluation of left ventricular function in coronary artery disease

Fifty-six patients with chest pain underwent selective coronaryangiography,radionuclide ventriculography (RNV) and frequency domaincardiography (FCG) to evaluate left ventricular function in coronary artery dis-ease (CAD).The sensitivity,specificity and accuracy of FCG were 87.5%,77.8%and 82.9%,respectively,which were slightly less than those of RNV (92.5%,88.9% and 90.8%,respectively).The changes of FCG scores were negatively corre-lated with changes of LVEF (r=-0.586,P【0.01),and TS (r=-0.679,P【0.01).These results indicate that FCG may be useful for the evaluation of leftventricular function in patients with CAD.

Non-invasive cuffless blood pressure and heart rate monitoring using impedance cardiography

Background Continuous blood pressure(BP)monitoring provides additional information about how changes in BP may correlate with daily activities and sleep patterns.Recommendations from the American Heart Association and American College of Cardiology strongly suggest confirming a diagnosis of hypertension with continuous BP monitoring.Non-invasive and non-intrusive detection of haemodynamic parameters is emerging as a norm,based on self-monitoring wearable medical devices.Researchers have carried out several studies using non-invasive and continuous BP measurements as an alternative to conventional cuff-based measurements.In this work,we proposed a novel method for cuffless estimation of BP using impedance cardiography(ICG).Methods We conducted a single-centre,cross-sectional study of 104 subjects(of whom 30 were categorized as controls and the remaining 74 as the disease group)at the Medical College and Hospital,Kolkata.The disease group consisted of patients with confirmed coronary artery disease,while the individuals in the control group were deemed to be healthy.All subjects underwent electrocardiogram recording by on-duty doctors in order to determine their health status.A custom-made device based on the principle of impedance plethysmography was designed to record impedance changes due to subjects’peripheral blood flow.The device was used to record ICG signals.In this study,we developed a novel auto-adaptive algorithm based on ICG signals for non-invasive,cuffless,continuous monitoring of BP and heart rate.Separate mathematical models were developed for all the estimated parameters(BP and heart rate)for both the study groups(control and disease).The developed models were auto-adaptive and did not require subject-specific calibration.Performance indicators including,𝑟2,error percentage,standard deviation,and mean difference were used to quantify the performance of the models.Results The ICG signal recorded by the device was used to extract features and compute the augmentation index.The calculated augmentation index values showed strong correlations with systolic BP(𝑟=0.99,𝑃<0.05),diastolic BP(𝑟=0.95,𝑃<0.05),and heart rate(𝑟=0.78,𝑃<0.05).The models were also shown to have a high degree of accuracy for systolic and diastolic BP.Error margins were in the range±2.33 and±1.79 mmHg for systolic BP in disease and control subjects,respectively,and±3.60 and±1.82 mmHg for diastolic BP.However,the accuracy was lower in the prediction of heart rate in disease subjects,with a reported𝑟2 value of 0.72 and an error margin of±2.88 beats per min;for healthy subjects,the results were marginally better,with an error margin of±1.82 beats per min.All statistical analyses were performed using MATLAB(R2017a,MathWorks R○,USA).Conclusion In this study,we developed a non-invasive cuffless approach for estimation of systemic peripheral BP and heart rate using ICG.The proposed methodology eliminated any discomfort to patients caused by inflation of the cuff(in the case of cuff-based BP monitoring)or the need to constantly wear a fingertip photoplethysmography device(in the case of cuffless BP monitoring).The results obtained appeared promising and increased the potential scope of ICG for monitoring other haemodynamic parameters related to heart function.

阻抗心动描记法的研究现状和进展

目前医院获得血流动力学参数大多采用有创手段如脉搏指示连续心输出量监测（PiCCO）,由于其并发症及费用等因素,制约着它的临床应用。阻抗心动描记法（impedance cardiography,ICG）是一种无创血流动力学监测方法,以电传导为基础,人体主动脉的血液比肺部气体的导电性好,绝大多数的电信号通过主动脉传导,随着每一次心跳,主动脉内血液的容量和血流速度发生变化,血流的电阻也随之变化。

Development of a low cost fetal heart sound monitoring system for home care application

Variations in fetal heart rate (FHR) is a potential indicator of stress on unborn in the womb of mother. In hospitals, FHR surveillance is performed by ultrasound based Doppler equip-ments. However, recent studies show that frequent exposure to ultrasound radiations is not recommended for the fetal well-being. Because of this and many other reasons, these instruments are not recommended for prolonged home monitoring applications. This work is focused around development of a prototype system for fetal home monitoring application. Presented system can record the abnormal FHR and alert the pregnant women to report to a physician. Recorded data is then processed by a novel methodology for deriving results of diagnostic importance. The instrument has been tested on pregnant women in the clinical environment and has gone through an extensive clinical trial at local hospitals. The results show that the technique is suitable and effective for long-term FHR home monitoring application.

NEURO-INDOCRINAL CHANGES DURING ACUPUNCTURE OR GENERAL ANESTHESIA FOR CRANIOCEREBRAL OPERATIONS

This study compared the hemodynamic changes during acupuncture anesthesiaand N2O-O2-enflurane inhalating anesthesia for craniotomy with impedance cardiography.