第二心音信号的瞬时功率和功率谱极大值分析

将时频分析方法用于第二心音的分析，研究了正常和异常第二心音信号的时频谱，根据时频分布的边缘条件，给出了第二心音的瞬时功率极大值和功率谱极大值特性，并将其作为描述心脏生理病理特性的量化指标。结果表明时频谱反映了第二心音各个成分在时频平面的能量分布及动态变化过程，瞬时功率极大值和功率谱极大值描述了第二心音信号的时变特征。     

体检时发现心脏有杂音要紧吗

最近我在医院体检时，医生说我的心脏有杂音，我对心脏杂音不了解、所以很紧张。请问心脏有杂音要紧吗？     

三种时频表示方法在心音信号分析中的研究应用

本文比较研究了短时傅里叶变换和连续小波变换以及ＡＲ谱谱阵在心音信号时－频分析方面的性能差异，指出了应用这三种方法应该注意的问题，并对正常的第二心音信号的时频分析进行了研究。结果表明，连续小波变换在反映信号的时频特性方面（谱峰值、谱峰的位置、谱的分布）具有比另外两种方法高的性能。     

体检时发现心脏有杂音要紧吗？

编辑同志： 最近我在医院体检时被医生提及发现心脏有杂音，由于我对心脏杂音了解不多，所以很紧张。请问心脏有杂音要紧吗？     

心脏杂音是怎么回事

学生在毕业、升学、参军、就业等时,都要进行身体健康检查。体检时常发现部分同学心脏有杂音。这些同学因此而不安。心脏杂音是怎么回事?影响健康、升学、参军、就业吗? 心脏杂音是指由心脏或其瓣膜所发出的一种异常的声音。它是由于血流加速或紊乱而产生的漩涡,使心壁或血管壁发生振动而形成。 心脏杂音一般分为生理性杂音(也称功能性杂音)和病理性杂音(也称器质性杂音)。生理性杂音常见于心脏无明显解剖或功能异常     

青少年左室假腱索与心脏杂音关系探讨

分析42例青少年左室假腱索超声心动图检测及心脏听诊结果，探讨左室假腱索与心脏杂音的关系。结果21例为收缩期喷射性杂音，12例为收缩或拍击者，9例为全收缩期杂音。假腱索呈横向型24例，纵向型18例；线状回声27例，带状回声15例。收缩期拍击音所占比例，在横向型及带状假腱索中发生率高，收缩期喷射性杂音在纵向型中发生率高，差异均有显著性（P＜0．05）。结果提示青少年左室假腱索可闻及多种心脏杂音，杂音的产生及性质可能与假腱索走向及形态有关。     

心脏有杂音 能否再锻炼

有些经常参加体育锻炼的人,在体格检查时,医生发现他们心脏有杂音,就产生一些疑问:心脏杂音是不是体育锻炼引起的?有了心脏杂音还能不能从事大运动量锻炼?     

青少年左室假腱室与心脏杂音关系探讨

分析了４２例青少年左室假腱索超声心动图检测及心脏听诊结果，探讨左室假腱索与心脏杂音的关系。结果２１例为收缩期喷射性杂音，１２例为收缩期拍击音，９例为全收缩期杂音，假腱索呈横向型２４例，纵向１８例；线状回声２７例，声状回声１５例。收缩期拍击音所占比例，在横向型及带状假腱索中发生率高，收缩期喷射性杂音在纵向型中发生率高，差异无有显著性。     

应届高中生左心室假腱索隋况分析

目的：探讨左心室假腱索（LVFT）与心脏杂音、心律失常的关系。方法：2825名高中生在内科体检中检出心脏杂音、心律失常（室性早搏）者,均列为人选条件。均进行心脏超声及心电图检查,对其检查结果进行分类,并对左心室假腱索与心脏杂音、心律失常的相关性进行分析。结果：2825人中检出心脏杂音306人,心律失常（室性早搏）11人,共317人,心脏超声检出LVFT共96人,心脏杂音306人中有85人检出LVFT,心律失常（室性早搏）11人中心脏超声均检出LVFT。结论：心脏有杂音者不一定有LVFT存在,对心律失常者,特别是在运动后出现或加重的室性早搏需要做进一步检查,及时发现心血管系统存在的隐患,并给予必要的医学干预,防止意外的发生。     

心脏杂音

心脏听诊可为心脏病的诊断提供极为有力的依据，虽然当今心脏检查的方法甚多，但均不能替代心脏的听诊。心脏杂音是心脏听诊的主要内容之一，它是指除心音和额外心音之外，由心室、瓣膜或血管振动产生的异常声音，它的特点是持续时间较长，性质特异，可与心音分开或连续，甚至掩盖心音。由于杂音的不同特性，对某些心脏病的诊断有重要意义。[第一段]     

Accurate assessment of heart murmurs in children: thorough medical history and physical examination required

4 children, boys aged 12, 5, 1.5 and 11 years, had a heart murmur. The 12-year-old boy could also not finish a football match and appeared to have atrioseptal defects (ASD). The 1.5-year-old boy had pulmonary symptoms that were not responsive to asthma medication; he also had ASD. The 11-year-old boy had had chest pain and pressure following exertion for 2 years; he appeared to have an aortic stenosis. Symptoms disappeared in all 3 patients after surgical correction. In the 5-year-old asymptomatic boy the murmur was deemed to be innocent following medical history and physical examination. Children frequently have heart murmurs. Most heart murmurs are innocent but some are caused by heart defects. Careful evaluation of the medical history and physical examination are critical in the differentiation of innocent and pathological heart murmurs. Routine supplementary diagnostic tests in children with heart murmurs are of limited value and are often misleading. One should inquire about specific and nonspecific symptoms and also perform systematic inspection, palpation and auscultation to identify any characteristics that suggest a heart murmur caused by a heart defect.     

68例应征青年心脏杂音临床分析

目的探讨应征青年心脏杂音与器质性心脏病的相关性。方法选择听诊有心脏杂音的应征青年68例,运用超声心动图检测其心脏结构及血液流动的改变。结果经超声心动图检出有相应瓣膜返流46例(67.6%)、左室假腱索11例(16.2%)、房间隔缺损3例(4.4%),总检出率88.2%,淘汰率27.9%;在边缘状态性心脏杂音24例中,相应瓣膜返流21例(87.5%)、左室假腱索3例(12.5),检出率100%,淘汰率66.7%。结论常规心脏听诊与超声心动图检查相结合是客观评价心脏杂音性质的理想方法 ,适合于各类健康体检对心脏杂音性质的判断。     

Heart murmurs in infants and children

A system is presented for evaluation of heart murmurs in infants and children. The system places emphasis on identification of functional murmurs, which the physician encounters so frequently in daily practice. A three-part approach is presented which includes: (1) evaluation of cardiovascular status, (2) assessment of the heart murmur, and (3) decision regarding the need for further evaluation. This approach relieves the physician of the necessity to remember the multiple details of the many congenital cardiac lesions, and requires only the knowledge of a few easily remembered details about functional murmurs. The system enables the physician to confidently distinguish organic and functional murmurs and to decide which children need further evaluation and referral to the pediatric cardiologist.     

小波多分辨率理论在心音信号分析中的应用

目的：心音信号是人体重要生理信号之一,通过小波多分辨率理论,能够准确地区分正常心音与杂音成分,使用现代信号处理技术能有效地提高诊断效果。方法：以LabVIEW8.6为开发平台,利用小波多分辨率理论,对心音信号进行多层分解。结果：通过对心音信号不同层中的分析,可以准确地区分S1、S2以及心脏杂音,还可将心音信号正确地划分为收缩期杂音信号（SM）、舒张期杂音信号（DM）和正常信号。结论：分析结果证明,该方法能准确地区分正常心音与杂音成分,为心脏病的辅助诊断提供有效的参考。     

Blood pressure and heart murmurs in a rural population in the United Republic of Tanzania.

Hypertension, congestive heart failure, and valvular heart disease are frequently seen among hospital inpatients in the United Republic of Tanzania. A population survey was therefore carried out to determine the prevalence of hypertension and cardiac murmurs in a random sample of people aged 25-64 years living in an undeveloped rural area. Standard cardiovascular survey methods as recommended by WHO were used. Only mean systolic blood pressure in women increased with age; even so, the difference in mean levels between those aged 25-34 and 55-64 years was only about 1.6 kPa (12 mmHg). Hypertension was found to be uncommon, only 2% of subjects having blood pressures ≥ 21.3/ 12.7 kPa (≥ 160/95 mmHg). By means of multiple regression analysis, less than 10% of the variance in blood pressure levels could be explained by age and anthropometric measurements. Murmurs of grade 2 or more were detected in 17% of the men and 22% of the women, being most commonly heard at the apex (54%) and the left lower border of the sternum (31%). Mitral valve diastolic murmurs were heard in 4 of 275 women and these were asymptomatic. The cause of the high prevalence of systolic murmurs is unknown.     

Divergence in student and educator conceptual structures during auscultation training

Context Simulation‐based medical education allows trainees to engage in self‐regulated learning (SRL), yet research aimed at elucidating the mechanisms of SRL in this context is relatively absent. We compared ‘unguided’ SRL with ‘directed’ SRL (DSRL), wherein learners followed an expert‐designed booklet. Methods Year 1 medical students (n = 37) were randomly assigned to practise identifying seven cardiac murmurs using a simulator and video only (SRL group) or a simulator and video plus the booklet (DSRL group). All participants completed a 22‐item test 3 weeks later. To compare interventions, we analysed students’ diagnostic accuracy. As a novel source of evidence, we documented how participants autonomously sequenced the seven murmurs during initial and delayed practice sessions. In addition, we surveyed clinical educators (n = 17) to find out how they would sequence their teaching of these murmurs. Results The DSRL group used 50% more training time than the SRL group (p < 0.001). The groups’ diagnostic accuracy, however, did not differ significantly on the post‐test, retention test or transfer test items (p > 0.12). Despite practising with the expert‐defined ‘timing‐based’ approach to murmur diagnosis (i.e. systolic versus diastolic), 84% of DSRL participants implemented a location‐based approach (i.e. practising aortic murmurs separately from mitral murmurs) during a second, unguided practice session. Notably, most SRL participants used that same approach spontaneously. By contrast, clinical educators were split in their use of the timing‐based (n = 10) and the location‐based (n = 6) approaches. Chi‐squared analyses suggested educators’ conceptions for organising murmurs differed significantly from students’ conceptions. Conclusions Contrary to our predictions, directing students’ SRL produced no additional benefit and increased their practice time. Our findings suggest one potential source of these results was a divergence between student and educator conceptions for structuring the practice of cardiac auscultation skills. This phenomenon has not been well articulated in the medical education literature, and may have important implications in many (especially technology‐mediated) educational contexts.     

Aortic stenosis presenting with predominant right heart failure

Two cases of severe aortic stenosis presenting with pure right heart failure and unimpressive cardiac murmurs are reported. Both responded well to aortic valve replacement. The mechanism of right heart failure is discussed as is the need for urgent surgery.     

Auscultation of the heart: a trial of classroom teaching versus computer-based independent learning

Declining skills in auscultation of the heart prompted an evaluation of teaching methods for medical students. A comparison of classroom teaching and computer-aided independent learning of auscultation was carried out with two groups of approximately 20 second-year medical students. Both groups used approximately 20 recorded normal and abnormal heart sounds and murmurs, chosen to illustrate learning issues. For the classroom group a cardiologist presented each case through multiple stethophones and led the discussion. The individual study group used a new CD-ROM collection of cases and recordings in quiz format, with a hypertext link to a comprehensive text on auscultation and additional recordings. Students were tested with 16 multiple choice and 5 open questions on eight selected recordings, and evaluated the teaching by questionnaire. The classroom-taught students scored higher on open questions than the CD-ROM-taught group, but in general performance by both groups was satisfactory and equivalent. Students of both groups repeatedly had difficulty classifying regurgitant and ejection murmurs and identifying characteristics of the second heart sound. Both CD-ROM and classroom teaching methods were highly rated by students but most students preferred a combination.     

Learning during simulation training is prone to retroactive interference

Medical Education 2012: 46 : 299–305 Context Retroactive interference occurs when newly acquired information inhibits recall of previously learned information. This has been shown to influence recall of sounds, tastes and word associations, and is typically seen when learners receive training on one area of content and are then exposed to new content before being evaluated on the original content. Thus far, retroactive interference has received little attention in medical education and has not been studied during simulation training. Our objective was to evaluate whether retroactive interference occurs during simulation training. Methods We randomised 167 Year 1 medical students to one of two training protocols. After training on a cardiac murmur, participants were tested either on the same cardiac murmur followed by a novel murmur (the non‐interference protocol), or on the novel murmur followed by the training murmur (the interference protocol). We evaluated performance on both murmurs at 1 hour and 6 weeks post‐training. Results We found a significant interaction between training protocol and diagnostic performance on training versus novel murmurs at both testing time‐points. Students in the non‐interference protocol had increased odds of achieving success on the training murmur relative to the novel murmur at 1 hour (odds ratio [OR] 4.96; p < 0.001) and at 6 weeks (OR 4.23; p = 0.001) after training. By comparison, students in the interference protocol did not demonstrate improved performance on the training murmur relative to the novel murmur at either evaluation (1 hour post‐training: OR 0.56 [p = 0.08]; 6 weeks post‐training: OR 0.66 [p = 0.23]). Conclusions Consistent with the theory of retroactive interference, students who encountered a novel murmur between training and evaluation on the murmur on which they had been trained showed no improvement in diagnostic performance following simulation training. These findings should serve to warn educators to consider retroactive interference when designing simulation training sessions.     

A review of the use of time-varying covariates in the Fine-Gray subdistribution hazard competing risk regression model

In survival analysis, time-varying covariates are covariates whose value can change during follow-up. Outcomes in medical research are frequently subject to competing risks (events precluding the occurrence of the primary outcome). We review the types of time-varying covariates and highlight the effect of their inclusion in the subdistribution hazard model. External time-dependent covariates are external to the subject, can effect the failure process, but are not otherwise involved in the failure mechanism. Internal time-varying covariates are measured on the subject, can effect the failure process directly, and may also be impacted by the failure mechanism. In the absence of competing risks, a consequence of including internal time-dependent covariates in the Cox model is that one cannot estimate the survival function or the effect of covariates on the survival function. In the presence of competing risks, the inclusion of internal time-varying covariates in a subdistribution hazard model results in the loss of the ability to estimate the cumulative incidence function (CIF) or the effect of covariates on the CIF. Furthermore, the definition of the risk set for the subdistribution hazard function can make defining internal time-varying covariates difficult or impossible. We conducted a review of the use of time-varying covariates in subdistribution hazard models in articles published in the medical literature in 2015 and in the first 5 months of 2019. Seven percent of articles published included a time-varying covariate. Several inappropriately described a time-varying covariate as having an association with the risk of the outcome.