Cardiac rhythm in healthy elderly subjects

Summary To study the normal cardiac rhythm in elderly subjects we performed 24-h Holter monitoring on 94 subjects aged over 70 years. We had previously discarded those with cardiac disease by using history, physical examination, electrocardiography (ECG), chest X-radiography and Doppler echocardiography. The maximum, average and minimum heart rates were 113, 79 and 62, respectively, during the day, and 90, 64 and 53 during the night. Supraventricular and ventricular arrhythmias were frequent (91% and 89.4% respectively). Some 50% of the subjects had complex ventricular arrhythmias. Two subjects presented with sinus pauses of more than 2 s, and 4 had Wenckebach second-degree atrioventricular (AV) block. During a follow-up averaging 20.8 months, there were no deaths or symptoms of an arrhythmic origin.Abbreviations ECG electrocardiogram - AV atrioventricular - HBP hypertension - AT atrial tachycardia - FC functional class - VT ventricular tachycardia - bpm beats per minute - SVE supraventricular extrasystoles - AF atrial fibrillation - VE ventricular extrasystole - W-AVB Wenckebach atrioventricular block     

Evaluating cardiac murmurs; are diagnostic tests helpful?

The detection of an asymptomatic murmur in a child usually results in a referral to a consultant paediatrician. In most cases a chest radiograph (CXR) and electrocardiograph (ECG) are performed as an aid to diagnosis, however the evidence for this is contradictory. A retrospective chart review of children referred with asymptomatic cardiac murmurs in a one-year period was conducted. We wished to determine whether CXR and ECG are useful diagnostic aids. 81 patient charts were reviewed. Of those patients with a clinical diagnosis of pathological murmur all had normal CXR and ECG. Never the less 2 cases were referred for echocardiogram and were found to have structural heart disease. Of those with a clinical diagnosis of innocent murmur most (81%) had a CXR and ECG and in most cases (96%) these were normal. Those cases with abnormal investigations subsequently were shown to have structurally normal hearts on echocardiogram. We conclude that routine use of CXR and ECG in evaluating asymptomatic cardiac murmurs in children is not useful.     

Sudden death caused by heart block in a patient with multiple myeloma and cardiac amyloidosis

A patient with multiple myeloma and amyloidosis was admitted to hospital following successful cardiopulmonary resuscitation at home. No disturbances in heart rhythm were seen during the first 48 hours of continuous telemetric ECG recording. The patient died from ventricular asystole due to complete atrioventricular block, while he was on a 24-hour Holter monitoring the fifth night in hospital. Patients with known cardiac amyloidosis and syncope should undergo long-term ECG recordings, preferably by telemetry. Repeated registrations may be necessary to discover disturbances in heart rhythm.     

152例青年学生晕厥患者动态心电图分析

目的:评价动态心电图在青年晕厥患者中的诊断价值。方法:在152例青年晕厥患者中,进行了动态心电图和心电图检查。结果:对窦性心动过速,各种传导阻滞,Q-T间期延长的检出率与普通心电图差异不大,而对窦性静止,快-慢综合征,阵发性室上性心动过速,阵发性室性心动过速动态心电图明显优于普通心电图(P<0.01)。结论:动态心电图为诊断心源性晕厥可提供依据。     

Spatial indices of repolarization correlate with non-ST elevation myocardial ischemia in patients with chest pain

Mild-to-moderate ischemia does not result in ST segment elevation on the electrocardiogram (ECG), but rather non-specific changes in the T wave, which are frequently labeled as non-diagnostic for ischemia. Robust methods to quantify such T wave heterogeneity can have immediate clinical applications. We sought to evaluate the effects of spontaneous ischemia on the evolution of spatial T wave changes, based on the eigenvalues of the spatial correlation matrix of the ECG, in patients undergoing nuclear cardiac imaging for evaluating intermittent chest pain. We computed T wave complexity (TWC), the ratio of the second to the first eigenvalue of repolarization, from 5-min baseline and 5-min peak-stress Holter ECG recordings. Our sample included 30 males and 20 females aged 63 ± 11 years. Compared to baseline, significant changes in TWC were only seen in patients with ischemia (n = 10) during stress testing, but not among others. The absolute changes in TWC were significantly larger in the ischemia group compared to others, with a pattern that seemed to depend on the severity or anatomic distribution of ischemia. Our results demonstrate that ischemia-induced changes in T wave morphology can be meaningfully quantified from the surface 12-lead ECG, suggesting an important opportunity for improving diagnostics in patients with chest pain.     

IgG4-Related Sclerosing Disease Involving the Superior Vena Cava and the Atrial Septum of the Heart

A 55-year-old woman presented with frequent episodes of syncope due to sinus pauses. During ambulatory Holter monitoring, atrial fibrillation and first-degree atrioventricular nodal block were observed. Magnetic resonance imaging and CT scans showed a tumor-like mass from the superior vena cava to the right atrial septum. Open chest cardiac biopsy was performed. The tumor was composed of proliferating IgG4-positive plasma cells and lymphocytes with surrounding sclerosis. The patient was diagnosed with IgG4-related sclerosing disease. Because of frequent sinus pauses and syncope, a permanent pacemaker was implanted. The cardiac mass was inoperable, but it did not progress during the one-year follow-up.     

Interrelationship between cardiac structure and function and incidence of arrhythmia in peritoneal dialysis patients

Cardiovascular complications in patients with end-stage renal disease requiring dialytic therapy are frequent and account for approximately 40% of all deaths in these patients. The aim of this study was to analyze the occurrence of cardiac arrhythmia in peritoneal dialysis (PD) patients with respect to the changes in left ventricular structure and function. To determine characteristics of arrhythmia in patients on PD for chronic renal failure, 30 patients (18 male and 12 female; aged 54.1+/-13.8 years) underwent twice (interval of 20+/-4.1 months) ambulatory 24 hour Holter ECG monitoring. At the same time all the patients were analyzed by echocardiography and pulsed Doppler echocardiography to estimate cardiac structure and function. Ventricular arrhythmias were seen in 9 patients (30%) during the first examination and in 13 patients (43.3%) on the second. Ventricular arrhythmias were observed only in patients with left ventricular hypertrophy (LVH). Supraventricular arrhythmias were seen in 12 (40%) and 17 (56.7%) patients. The majority of these patients also had LVH, with 11/12 (91.7%) patients at the first examination and 15/17 (88.2%) at the second respectively. We conclude that the incidence of arrhythmia is primarily dependent on the presence of LVH in PD patients. It appears that peritoneal dialysis does not provoke or aggravate arrhythmia.     

Development and preliminary clinical tests of an impedance sensing VDD recording pacemaker for diagnosis and research

Episodes of serious but infrequently occurring cardiac arrhythmias can be difficult to detect and analyse, even with modern Holter monitoring. A previous diagnostic pacemaker developed by this group provided VVI pacing therapy and recorded intracardiac ECG signals but had no atrial sensing or impedance measuring capability. A new external diagnostic pacemaker system is described that has been developed to assist in diagnosing intermittent arrhythmias by selectively recording intracardiac signals. Unlike other ambulatory monitors, in addition to recording ECG, the device combines VDD pacing therapy with the capability of monitoring and recording intracardiac impedance and pressure waveforms through a temporary intracardiac lead. A PCMCIA memory card allows storage of 48 arrhythmic events of 21 seconds each. Twelve seconds of waveform are retained before the event occurs and nine seconds after. Data retrieval and processing is performed with a PC which reconstructs each waveform for display. The ECG provides data on cardiac rhythm while cardiac function is inferred from the haemodynamic signals. During simulated trials, 14 event types were presented to the system. All events were successfully detected and recorded. During in vivo clinical tests 83 waveform recordings were made. Impedance fluctuations with typical peak-to-peak values of 64 ohms were successfully recorded.     

Generation of digital time database from paper ECG records and Fourier transform-based analysis for disease identification

ECG signals recorded on paper are transferred to the digital time database with the help of an automated data extraction system developed here. A flatbed scanner is used to form an image database of each 12-lead ECG signal. Those images are then fed into a Pentium PC having a system to extract pixel-to-pixel co-ordinate information to form a raw database with the help of some image processing techniques. These raw data are then ported to the regeneration domain of the system to check the captured pattern with the original wave shape. The sampling period of each ECG signal is computed after detection of QRS complex. Finally, discrete Fourier transform of the generated database is performed to observe the frequency response properties of every ECG signal. Some interesting amplitude properties of monopolar chest lead V4 and V6 are noticed which are stated.     

A wearable real-time telemonitoring electrocardiogram device compared with traditional Holter monitoring

Arrhythmias are very common in the healthy populations as well as patients with cardiovascular diseases. Among them, atrial fibrillation (AF) and malignant ventricular arrhythmias are usually associated with some clinical events. Early diagnosis of arrhythmias, particularly AF and ventricular arrhythmias, is very important for the treatment and prognosis of patients. Holter is a gold standard commonly recommended for noninvasive detection of paroxysmal arrhythmia. However, it has some shortcomings such as fixed detection timings, delayed report and inability of remote real-time detection. To deal with such problems, we designed and applied a new wearable 72-hour triple-lead H3-electrocardiogram (ECG) device with a remote cloud-based ECG platform and an expert-supporting system. In this study, 31 patients were recruited and 24-hour synchronous ECG data by H3-ECG and Holter were recorded. In the H3-ECG group, ECG signals were transmitted using remote real-time modes, and confirmed reports were made by doctors in the remote expert-supporting system, while the traditional modes and detection systems were used in the Holter group. The results showed no significant differences between the two groups in 24-hour total heart rate (HR), averaged HR, maximum HR, minimum HR, premature atrial complexes (PACs) and premature ventricular complexes (PVCs) (P>0.05). The sensitivity and specificity of capture and remote automatic cardiac events detection of PACs, PVCs, and AF by H3-ECG were 93% and 99%, 98% and 99%, 94% and 98%, respectively. Therefore, the long-term limb triple-lead H3-ECG device can be utilized for domiciliary ECG self-monitoring and remote management of patients with common arrhythmia under medical supervision.     

Development and preliminary clinical tests of an impedance sensing VDD recording pacemaker for diagnosis and research

Episodes of serious but infrequently occurring cardiac arrhythmias can be difficult to detect and analyse, even with modern Holter monitoring. A previous diagnostic pacemaker developed by this group provided VVI pacing therapy and recorded intracardiac ECG signals but had no atrial sensing or impedance measuring capability. A new external diagnostic pacemaker system is described that has been developed to assist in diagnosing intermittent arrhythmias by selectively recording intracardiac signals. Unlike other ambulatory monitors, in addition to recording ECG, the device combines VDD pacing therapy with the capability of monitoring and recording intracardiac impedance and pressure waveforms through a temporary intracardiac lead. A PCMCIA memory card allows storage of 48 arrhythmic events of 21 seconds each. Twelve seconds of waveform are retained before the event occurs and nine seconds after. Data retrieval and processing is performed with a PC which reconstructs each waveform for display. The ECG provides data on cardiac rhythm while cardiac function is inferred from the haemodynamic signals. During simulated trials, 14 event types were presented to the system. All events were successfully detected and recorded. During in vivo clinical tests 83 waveform recordings were made. Impedance fluctuations with typical peak-to-peak values of 64 ohms were successfully recorded.     

Transmission and non-transmission portable ECG in home care medicine

Portable electrocardiography is advantageous in that patients can record ECG by themselves at any time and place. Portable ECG can be classified into two kinds of devices, transmission type and non-transmission type. By using transmission-type portable ECG, patients can obtain an ECG diagnosis from the center by transmitting the recorded ECG. Transmission-type portable ECG is extremely useful for patients needing emergency treatment for such as an attack of ischemic heart disease or arrhythmic event. On the other hand, a patient has to go to a specialist to obtain an ECG diagnosis with the non-transmission-type portable ECG device after recording the ECG alone. As this model is slightly cheaper, and is easy to use, the non-transmission-type portable ECG is good in non-emergency use for early diagnosis and prevention of cardiac disease. Portable ECG is useful for ECG monitoring over time without seeing the patient, not only for symptomatic analysis of the patient. For example, silent myocardial ischemia and arrhythmic events developing during exercise will become clear in periodical portable ECG recording. In particularly, portable ECG is useful for noncontinual ECG monitoring of patients with Brugada syndrome and those administered with antiarrhythmic drugs. Portable ECG increases the opportunity to discover cardiac disease from the aspect of preventive medicine. When patients use a portable ECG during exercise, they can understand whether the exercise is suitable for their heart. Portable ECG is a useful measurement in preventive medicine as described above, not only for the home care of patients.     

常规心电图应用过程中存在的问题分析

目的:分析讨论常规心电图在临床应用中存在的不足。方法:选取2012年6月~2013年8月间来我院进行心电图检查的患者200例,分别进行常规心电图以及动态心电图检查,对患者的检查结果进行比较分析,着重比较确诊患有心脏病患者的检查结果。结果:常规心电图的阳性检出率48%,而动态心电图的阳性检出率则为66%,明显要高于常规心电图的检测结果。结论:常规心电图在临床检查中检查出心电异常的机率比动态心电图要低,诊断的阳性率也较低,因此有严重心脏病的患者还是应该采取动态心电图进行检查。     

Effective doses to patients undergoing thoracic computed tomography examinations

The purpose of this study was to investigate how x-ray technique factors and effective doses vary with patient size in chest CT examinations. Technique factors (kVp, mAs, section thickness, and number of sections) were recorded for 44 patients who underwent a routine chest CT examination. Patient weights were recorded together with dimensions and mean Hounsfield unit values obtained from representative axial CT images. The total mass of directly irradiated patient was modeled as a cylinder of water to permit the computation of the mean patient dose and total energy imparted for each chest CT examination. Computed values of energy imparted during the chest CT examination were converted into effective doses taking into account the patient weight. Patient weights ranged from 4.5 to 127 kg, and half the patients in this study were children under 18 years of age. All scans were performed at 120 kVp with a 1 s scan time. The selected tube current showed no correlation with patient weight (r2=0.06), indicating that chest CT examination protocols do not take into account for the size of the patient. Energy imparted increased with increasing patient weight, with values of energy imparted for 10 and 70 kg patients being 85 and 310 mJ, respectively. The effective dose showed an inverse correlation with increasing patient weight, however, with values of effective dose for 10 and 70 kg patients being 9.6 and 5.4 mSv, respectively. Current CT technique factors (kVp/mAs) used to perform chest CT examinations result in relatively high patient doses, which could be reduced by adjusting technique factors based on patient size.     

穿戴式随行监护系统心电信号质量评价研究

穿戴式生理参数监测技术是一种新型的生理监护技术,代表未来监护技术的发展方向,但该类技术应用于临床尚有许多问题亟待解决。本文针对自主研发的穿戴式随行监护系统(SensEcho-5B)的心电信号质量评价问题开展了探索性研究。首先基于模板匹配法开发出一种心电信号质量评价算法,用于心电信号的自动、定量评价,在100名受试者(15名健康人和85名心血管疾病患者)随机抽取的100 h心电信号数据集上进行了算法性能测试。在此基础上使用SensEcho-5B与心电Holter同步采集了30名受试者(7名健康人和23名心血管疾病患者)的24 h心电数据,使用心电信号质量评价算法对两个系统同步记录的心电信号质量进行评价。算法性能测试结果:敏感度为100%,特异度为99.51%,准确率为99.99%。30名受试者的对照试验结果:SensEcho-5B所检测到的心电信号,信号质量较差时间的中位数(Q1,Q3)为8.93(0.84,32.53)min,Holter所检测到的心电信号,信号质量较差时间的中位数(Q1,Q3)为14.75(4.39,35.98)min(秩和检验P=0.133)。研究结果表明,本文提出的心电信号质量评价算法能够对穿戴式随行监护系统的心电信号质量进行有效评价;随行监护系统SensEcho-5B与对照Holter相比,心电信号质量相当。后续研究将进一步在真实临床环境中采集大样本量的随行监护生理数据,并对心电信号质量进行分析和评价,从而使监护系统的性能得到持续优化。     

Removal of arterial wall calcifications in CT angiography by local subtraction

CT Angiography (CTA) is an established technique for the minimally invasive imaging of arteries. The technique of maximum intensity projection (MIP) is often used to get a comprehensive overview of the vascular anatomy. On a MIP, however, arterial wall calcifications may hinder the visualization of the arterial lumen. These calcifications are in direct contact with the contrast-enhanced blood, which makes removal difficult. We present a local subtraction method for the automatic removal of these calcifications. In our approach a second CT scan has to be made, prior to contrast injection. The calcifications in both scans are registered prior to subtraction to compensate for displacements in between the two scans. Local subtraction results are compared with results obtained by thresholding. The method was tested in a phantom and with data from four patients. The phantom represented an artery with different types of stenosis. Data were used from patients for which CTA of the renal arteries was performed. For two patients the electrocardiogram (ECG) was recorded during the CTA examination, making retrospective cardiac gated reconstructions possible. Both the phantom and the patient study showed that the local subtraction method is capable of removing calcifications and visualizing the residual lumen. In the patient study it appeared that some artifacts remained for higher pitch values. We conclude that the local subtraction method is less subjective and more accurate than thresholding. Best results are obtained by use of a small pitch, at the expense of the volume covered during a single breath hold.     

面向家庭健康监护的心电监护系统设计

目的研制一款面向家庭的心电监护系统。方法以基于ARM920T的s3c2440为核心,控制心电信号采集,并结合嵌入式软件技术,实时显示、分析和记录心电信号,对患者进行监护。算法部分采用适用于嵌入式系统的动态差分阈值法检测QRS波波群。结果该监护系统能实时、动态显示心电波形,并可以识别4种心率异常,能较好地反映和分析患者的心电活动状况。结论该心电监护系统操作简便,运行稳定,能够满足一般家庭需求,具有良好的应用前景。     

Frequency-plane analysis of normal and pathological ECG signals for disease identification

In this paper a frequency plane analysis of both normal and diseased ECG signals is performed specifically for disease identification. Image processing techniques are used to develop an automated data acquisition package of 12 lead ECG signals from paper records. A regeneration domain is also developed to check the captured pattern with the original wave shape. A QRS complex detector with an accuracy level approximately 98.4% in up to 30% signal to noise level is developed. Discrete Fourier transform (DFT) is performed to obtain the frequency spectrum of every ECG signal. Some interesting amplitude and phase response properties of chest lead V2, V3, V4, V6 and limb lead I, II, III, AVL, AVF are seen. Both amplitude and phase properties are different for normal and diseased subjects and can serve an important role in disease identification. A statistical analysis of amplitude property is carried out to show that this property is significantly different for normal and diseased subjects.     

Frequency-plane analysis of normal and pathological ECG signals for disease identification

In this paper a frequency plane analysis of both normal and diseased ECG signals is performed specifically for disease identification. Image processing techniques are used to develop an automated data acquisition package of 12 lead ECG signals from paper records. A regeneration domain is also developed to check the captured pattern with the original wave shape. A QRS complex detector with an accuracy level ～98.4% in up to 30% signal to noise level is developed. Discrete Fourier transform (DFT) is performed to obtain the frequency spectrum of every ECG signal. Some interesting amplitude and phase response properties of chest lead V2, V3, V4, V6 and limb lead I, II, III, AVL, AVF are seen. Both amplitude and phase properties are different for normal and diseased subjects and can serve an important role in disease identification. A statistical analysis of amplitude property is carried out to show that this property is significantly different for normal and diseased subjects.     

Using simulated noise to define optimal QT intervals for computer analysis of ambulatory ECG

The ambulatory electrocardiogram (ECG) is an important medical tool, not only for diagnosis of adverse cardiac events, but also to predict the risk of such events occurring. The 24-hour ambulatory ECG has certain problems and drawbacks because the signal is corrupted by noise from various sources and also several other conditions which may alter the ECG morphology. We have developed a Windows based program for the computer analysis of ambulatory ECG which attempts to address these problems. The software includes options for importing ECG data, different methods of waveform analysis, data-viewing, and exporting the extracted time series. In addition, the modular structure allows for flexible maintenance and expansion of the software. The ECG was recorded using a Holter device and oversampled to enhance the fidelity of the low sampling rate of the ambulatory ECG. The influence of different sampling rates on the interval variability were studied. The noise sensitivity of the implemented algorithm was tested with several types of simulated noise and the precision of the interval measurement was reported with SD values. Our simulations showed that, in most of the cases, defining the end of QT interval at the maximum of the T wave gave the most precise measurement. The definition of the onset of the ventricular repolarization duration is most precisely made on the maximum or descending maximal slope of the R wave. We also analyzed some examples of time series from patients using power spectrum estimates in order to validate the low level QT interval variability.