Comparison of two diagnostic algorithms for regular broad complex tachycardia by decision theory analysis

Sensitivity and specificity are two inversely related properties of a diagnostic test and it is often practically infeasible to secure a high value for both simultaneously. Decision theory analysis shows that the utility of a diagnostic test depends not only on its sensitivity and specificity but also on the prevalence of the intended target disorder: when prevalence is low, a high specificity is more important than a high sensitivity, whereas when prevalence is high, a high sensitivity is more important than a high specificity. The significance of this principle is illustrated by two popular algorithms for the electrocardiographic diagnosis of regular broad complex tachycardia (BCT), of which the two main differential diagnoses are ventricular tachycardia (VT) and supraventricular tachycardia with aberrant conduction (SVTAG). Brugada et al. focused on criteria highly specific for VT and used them to build a four-step algorithm. In contrast, Griffith et al. first selected criteria highly sensitive for VT and then criteria highly specific for VT to build a simple two-step algorithm. It can be objectively demonstrated that the Griffith algorithm is more efficient and effective than the Brugada algorithm in terms of clinching the final diagnosis and improving overall diagnostic accuracy. The main reason for this is that VT is more common than SVTAC as the cause of regular BCT, and the Griffith algorithm adhered to the aforementioned principle governing the choice between sensitivity and specificity according to prevalence in its design. The Griffith algorithm also embodies an additional important principle, namely, it is easier and more efficient to choose alternatively between criteria highly specific and highly sensitive for the intended target disorder than concentrating on just one or the other in designing a multiple-step sequential diagnostic algorithm.     

Comparison of the performance of three diagnostic algorithms for regular broad complex tachycardia in practical application

The authors previously proposed a Bayesian approach to the electrocardiographic diagnosis of regular broad complex tachycardia (BCT), which can be due to VT or supraventricular tachycardia with aberrant conduction (SVTAC). They also published an account comparing the theoretical merits in the design of two of the most commonly used diagnostic algorithms for the same purpose, those of Brugada et al. and Griffith et al. In this study, a direct head-to-head comparison was performed on the practical performances of the three algorithms in this study. A set of 111 ECGs showing regular BCT (77 VT, 34 SVTAC) whose diagnoses were confirmed by electrophysiological study was shown to five internists in general medicine at a district general hospital. The observers were asked to comment on whether the ECG criteria in the three algorithms tested were fulfilled or not, and a computer program then derived the corresponding diagnoses. The sensitivity and specificity for VT achieved by the Brugada algorithm were 92% and 44%, 92% and 44% by the Griffith algorithm, and 97% and 56% by the Bayesian algorithm. The Bayesian algorithm achieved a higher sensitivity and specificity than the other two algorithms, but the differences are not statistically significant (P = 0.6583 and P = 0.5334, respectively). The Brugada, Griffith, and Bayesian algorithms show comparable performances in terms of overall sensitivity and specificity when tested in practice. Of the three algorithms, the Griffith algorithm excels in simplicity and is the easiest to implement in practice. The Bayesian algorithm achieved slightly higher values for sensitivity and specificity than the Brugada and Griffith algorithms but may be more suitable for automated computer-aided diagnosis of ECG due to its complexity.     

Electrocardiographic criteria for diagnosis of irregular broad complex tachycardia with a high sensitivity for preexcited atrial fibrillation

AF may appear as an irregular broad complex tachycardia (BCT) if atrioventricular conduction occurs via an accessory pathway (preexcited AF) or if bundle branch block (BBB), preexistent or rate related, exists in the His-Purkinje system (BBB-AF). While BBB-AF is relatively benign, preexcited AF may herald sudden cardiac death. Hence it is important that the two conditions can be reliably distinguished. Yet, there is no preexistent algorithms for this purpose. Griffith et al. previously proposed a simple algorithm for a similar problem, that of distinguishing the two differential diagnoses for regular BCT: VT and SVT with BBB, on the basis that unless the QRS morphologies in V1 and V6 are absolutely typical of BBB, VT will be diagnosed. The authors propose an extrapolation of this principle to irregular BCT by stating that, unless the QRS morphologies in V1 and V6 are absolutely typical of BBB, preexcited AF will be diagnosed. Seventy-five ECGs showing irregular BCT (41 preexcited AF and 34 BBB-AF) were shown to two fellows in electrophysiology who were given no other information and were instructed to diagnose preexcited AF unless the QRS morphology pattern was typical of BBB. Observer 1 achieved a sensitivity of 100% (41/41) and a specificity of 79% (27/34), while observer 2 achieved a sensitivity of 100% and a specificity of 85% (29/34). By QRS morphology pattern, an average sensitivity of 100% and specificity of 82% were achieved for the diagnosis of irregular BCT. The algorithm is simple and easy to implement and recommended for clinical use.     

The differential diagnosis of wide QRS complex tachycardia

Wide complex tachycardia is defined as a cardiac rhythm with a rate greater than 100 beats/min (bpm) and a QRS complex duration greater than 0.10 to 0.12 seconds (s) in the adult patient; wide complex tachycardia (WCT) in children is defined according to age-related metrics. The differential diagnosis of the WCT includes ventricular tachycardia and supraventricular tachycardia with aberrant intraventricular conduction, including both relatively benign and life-threatening dysrhythmias. This review focuses on the differential diagnosis of WCT with a discussion of strategies useful in making the appropriate diagnosis, when possible.     

肢体导联反向法和室性心动过速积分法在鉴别预激性心动过速中的临床价值

目的探讨肢体导联反向法和室性心动过速（VT）积分法在鉴别预激性心动过速中的临床价值。 方法回顾性分析2013年1月至2021年6月首都医科大学附属北京友谊医院经心内电生理确诊为预激性心动过速的住院患者18例,收集患者发作时的12导联心电图,分别采用肢体导联反向法和VT积分法进行评分。采用χ²检验比较二者诊断预激性心动过速的特异度差异,并分析2种流程诊断预激性心动过速不同类型和不同旁路位置中的特异度。 结果18例患者中,肢体导联反向法诊断的真阳性11例,特异度为38.89%;VT积分法积分≥2分、≥3分诊断预激性心动过速的特异度分别为55.56%、100.00%。肢体导联反向法与VT积分法积分≥2分诊断预激性心动过速的特异度比较,差异无统计学意义（P＞0.05）;肢体导联反向法与VT积分法积分≥3分的特异度比较,差异有统计学意义（P＜0.05）。2种诊断流程对不同类型和旁路位置预激性心动过速诊断的特异度差异无统计学意义（P＞0.05）。 结论VT积分法积分≥3分可区分预激性心动过速和VT,肢体导联反向法和VT积分法≥2分则不能区分。     

彩色室壁运动分析技术评估心肌梗死后左室壁的运动

目的评价CK技术评估心肌梗塞患者室壁运动的价值。方法应用Philips Sonos 7500型彩色多普勒超声诊断仪(具有CK技术)对14例心肌梗患者的室壁运动及11例正常对照组左室各节段室壁运动进行检测与对比分析。结果心肌梗塞患者的CK图像显示,梗死部位的室壁收缩与舒张时心内膜彩阶位移缩小,彩阶层次消失;正常组左室的CK图像显示,室壁各节段厚度均匀,连续完整,分步对称的彩色环。结论CK技术是评价心肌梗塞患者室壁运动异常的一种准确、敏感的无创手段。     

The Bayesian Approach Improves the Electrocardiographic Diagnosis of Broad Complex Tachycardia

LAU, E.W., et al. : The Bayesian Approach Improves the Electrocardiographic Diagnosis of Brand Complex Tachycardia. Despite numerous attempts at devising algorithms for diagnosing broad complex tachycardia (BCT) on the basis of the electrocardiogram (ECG), misdiagnosis is still common. The reason for this may lie with difficulty in implementing existent algorithms in practice, due to imperfect ascertainment of ECG features within them. An attempt was made to approach the problem afresh with the Bayesian inference by the construction of a diagnostic algorithm centered around the likelihood ratio (LR). Previously studied ECG features most effective in discriminating ventricular tachycardia (VT) from supraventricular tachycardia with aberrant conduction (SVTAC), according to their LR values, were selected for inclusion into a Bayesian diagnostic algorithm. A test set of 244 BCT ECGs was assembled and shown to three independent observers who were blinded to the diagnoses made at electrophysiological study. Their diagnostic accuracy by the Bayesian algorithm was compared against that by clinical judgement with the diagnoses from EPS as the criterial standard. Clinical judgement correctly diagnosed 35% of SVTAC, 85% of VT, and 47% of fascicular tachycardia. In comparison, by the Bayesian algorithm devised, 52% of SVTAC, 95% of VT, and 97% of fascicular tachycardia were correctly diagnosed. The Bayesian algorithm devised has proved to be superior to the clinical judgement of the observers who participated in this study, and theoretically will obviate the problem of imperfect ascertainment of ECG features. Hence, it holds the promise for being an effective tool for routine use in clinical practice.     

aVR导联ST段抬高对窄QRS波心动过速的鉴别及旁道定位作用

目的:观察aVR导联ST段抬高对窄QRS波心动过速的鉴别及旁道定位作用。方法:120例窄QRS波心动过速均经心内电生理和射频消融证实,分析其心动过速发作时体表12导联心电图aVR导联ST段抬高程度及持续时间。结果:120例窄QRS波心动过速中有58例房室折返性心动过速(AVRT),62例房室结折返性心动过速(AVNRT)。aVR导联ST段抬高在AVRT发生率为67.2%,AVNRT为16.1%(P<0.05),诊断AVRT的敏感性、特异性和准确性分别是67.2%、83.9%和75.8%。在39例aVR导联ST段抬高的AVRT中,有28例位于左旁道,7例位于右旁道,3例位于后间隔,1例位于前间隔。aVR导联ST段抬高定位左侧旁道的敏感性、特异性、阳性预测值和准确性分别是77.8%、50.0%、71.8%和76.5%。结论:aVR导联ST段抬高有助于鉴别窄QRS波心动过速及旁道定位。     

Review article: The utility of troponin and other investigations in patients presenting to the emergency department with supraventricular tachycardia

Patients with supraventricular tachycardia commonly present to the ED. There is a lack of consensus regarding assessment of these patients. Our aim was to determine the utility of troponin and four other investigations (full blood examination, electrolyte levels, thyroid function tests and chest X-rays) commonly requested for these patients. MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (January 1992–March 2017) were searched for randomised controlled trials and observational studies (of sample size greater than 10). Our search strategy yielded no randomised controlled trials and seven observational studies with significant statistical heterogeneity among selected studies (I² 87.3%, P < 0.001). Included studies investigated a total of 1155 patients. All studies reported on the utility of troponin testing in this patient population. The pooled proportion of patients investigated with troponin was 0.66 (95% confidence interval 0.44–0.88). The pooled proportion of positive troponin tests was 0.32 (95% confidence interval 0.23–0.41). Only one study reported on the utility of the remaining four investigations with abnormal results as follows: thyroid stimulating hormone 14%, haemoglobin 6%, white cell count 19% and chest X-ray 22%. Investigations are commonly requested for patients presenting with supraventricular tachycardia. Troponin testing is commonly performed with a high proportion of positive findings although these results did not appear to be associated with major adverse cardiac events. Heterogeneity among studies and low levels of evidence precluded conclusions on full blood examinations, electrolyte levels, thyroid testing and utility of chest X-rays in this patient population.     

The application of Cartwright's concept of capacities to complex interventions in psychiatry

Cartwright and Munro argued that extrapolation of findings from randomized controlled trials to other settings can be difficult because information about the underlying causal structure and subgroups is often not available. They advocated the use of ‘capacities’ – that is fixed causal contributions – in predicting effects of interventions. In psychiatry, it is often not possible to determine what the fixed causal contributions are and one can only establish ‘approximate capacities’. However, using ‘approximate capacities’ does imply a different way of evaluating health services, especially combined interventions. In health service research, if different studies, randomized controlled trials or other designs, have given different outcomes, the best way to investigate the effectiveness of a particular way of service organization is not to conduct more randomized controlled trials. It is preferable to study the effects of certain elements of the complex intervention, which have been tested before in other settings, that is investigating ‘approximate capacities’. One should check whether the separate elements do form a part of the complex intervention in practice and whether they have the same effect as in other studies and if not, why not. This enhances knowledge about the underlying causal structure and increases the possibility of extrapolation of the findings.     

Standardization and evaluation of a tetraplex polymerase chain reaction to detect and differentiate Mycobacterium tuberculosis complex and nontuberculous Mycobacteria--a retrospective study on pulmonary TB patients

The clinical presentation of pulmonary tuberculosis by members of Mycobacterium tuberculosis complex (MTC) and nontuberculous mycobacteria (NTM) cannot be differentiated using the available standard diagnostic procedures. A single-tube tetraplex polymerase chain reaction (T-PCR) was designed to simultaneously amplify 4 well-known DNA targets of MTC. Taguchi's protocol was followed for the optimization of the conditions and was then tested on 288 pulmonary TB patient samples. The analytical sensitivity of the T-PCR was 100 fg of purified mycobacterial DNA, and specificity was found to be 100% in being able to distinguish MTC and NTM in all the cases tested. The results correlated well when validated with hsp65 PCR restriction analysis and sequencing of the 16S-23S internal transcribed spacer region, hsp65, and rpoB. The T-PCR described here is a quick, valuable, and cost-effective tool for determining whether the causative organism is MTC or NTM, and thus is useful for disease surveillance.     

The value of small bowel wall contrast enhancement after sulfur hexafluoride-filled microbubble injection to differentiate inflammatory from fibrotic strictures in patients with Crohn's disease

We analysed the value of contrast-enhanced ultrasound to differentiate inflammatory from fibrotic ileal strictures in patients with Crohn's disease (CD). Twenty-eight patients (17 male and 11 female; mean age ± SD, 48.5 ± 17.17 years) with a biopsy-proven diagnosis of CD were included. In each patient, the terminal ileal loop was scanned by a convex-array probe (2-5 MHz) before and after sulphur hexafluoride-filled microbubble injection. The digital cine-clip registered after microbubble injection during the first-pass dynamic enhancement was quantified in gray-scale levels by a dedicated software through manually drawn regions-of-interest (ROIs) encompassing the anterior bowel wall. Time-intensity curves from patients with inflammatory and fibrotic ileal strictures, fitted according to the theoretical gamma variate curve, were compared. Inflammatory vs. fibrotic ileal strictures differed in the percentage of maximal enhancement (45.86 ± 5.32 vs. 37.33 ± 16.24%; p < 0.05) and area under the enhancement curve (1168.25 ± 437.65 vs. 570.47 ± 323.08; p < 0.05), whereas the difference in time to peak enhancement was found not significant (9.25 ± 4.21 vs. 12.01 ± 7.34 s; p > 0.05). The quantitative analysis of small bowel wall contrast enhancement after microbubble contrast agent injection may differentiate inflammatory from fibrotic ileal strictures in patients with CD.     

The anterior complex: A visual mnemonic to aid in identification of normal structures

The anterior complex of the fetal brain is a group of structures that are important to evaluate during the routine anatomic survey to exclude several serious brain malformations. These structures include the cavum septum pellucidum, anterior horns, interhemispheric fissure, callosal sulcus, and corpus callosum. The relationship between these structures is easily remembered with the presented visual cartoon. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45 :477–479, 2017     

The role of music therapy in an interdisciplinary approach to address functional communication in complex neuro-communication disorders: A case report

Purpose. This paper presents a case report of collaborative work between speech and language therapy (SLT) and music therapy (MT) in the case of an individual presenting with complex communication difficulties and lability caused by pseudo-Parkinsonian vascular disease.

Design. MT intervention was used to investigate whether participation could be enabled in a client presenting with complex problems as well as facilitate change in communication parameters which remained unresponsive to conventional SLT intervention. A single case design measured communication and well-being parameters using pre-, during and post-intervention measures. In addition, analysis of the client's musical responses was undertaken to examine changes in vocal functioning which are involved in communication.

Results. Analysis of the client's performance during MT intervention revealed improvements in prosody and phonation, with positive reports of participation, reduced incidence of lability and improvements in measures of well-being.

Conclusions. The results indicate the value of such collaborative working in addition to making recommendations for the modification of existing treatment protocols. The findings highlight that fatigue is a major consideration when working with people with severe and complex clinical presentations.     

The role of music therapy in an interdisciplinary approach to address functional communication in complex neuro-communication disorders: a case report

Purpose. This paper presents a case report of collaborative work between speech and language therapy (SLT) and music therapy (MT) in the case of an individual presenting with complex communication difficulties and lability caused by pseudo-Parkinsonian vascular disease.

Design. MT intervention was used to investigate whether participation could be enabled in a client presenting with complex problems as well as facilitate change in communication parameters which remained unresponsive to conventional SLT intervention. A single case design measured communication and well-being parameters using pre-, during and post-intervention measures. In addition, analysis of the client's musical responses was undertaken to examine changes in vocal functioning which are involved in communication.

Results. Analysis of the client's performance during MT intervention revealed improvements in prosody and phonation, with positive reports of participation, reduced incidence of lability and improvements in measures of well-being.

Conclusions. The results indicate the value of such collaborative working in addition to making recommendations for the modification of existing treatment protocols. The findings highlight that fatigue is a major consideration when working with people with severe and complex clinical presentations.