Differentiation of paroxysmal narrow QRS complex tachycardias using the 12-lead electrocardiogram

Usefulness of the intracardiac electrocardiogram recorded using central venous catheters on P-wave magnification

BACKGROUND

The detection of atrial electrical activity is extremely valuable in recognizing complex cardiac arrhythmias. However, P-wave detection on a surface electrocardiogram (S-ECG) can sometimes be challenging. The intracardiac electrocardiogram (IC-ECG), recorded by a central venous catheter loaded with saline solution, has proven to be a safe and effective method for amplifying atrial electrical activity. We aim to compare the P-wave amplitude recorded in the S-ECG and the IC-ECG in different venous accesses, catheters, heart rhythms, and atrial dimensions.

METHODS

We compared the P wave amplitude obtained by the IC-ECG and the S-ECG recordings from cardiac intensive care unit patients.

RESULTS

In 109 nonconsecutive patients, a total of 166 IC-ECG were collected. The median amplitude of the P wave was 0.1 (0.083-0.3) mV in the S-ECG and 0.4 (0.25-2.4) mV in the IC-ECG; p < 0.001. This difference remained significant regardless of the patient's heart rhythm, left atrial dimension, and catheter or vascular access used.

CONCLUSION

The IC-ECG acquired using central venous catheters significantly increases atrial electrical activity signals. This technique might help identify complex cardiac arrhythmias.

Localization and characterization of atrial depolarization waves on the surface electrocardiogram in dogs with rapid supraventricular tachycardia

BACKGROUND

Supraventricular tachycardias (SVTs), despite having various anatomical substrates and pathophysiological mechanisms, frequently show similar electrocardiographic presentations.

OBJECTIVES

To locate and characterize atrial deflections (ADs) on 12-lead electrocardiograms in dogs with sustained rapid SVT and assess the utility of different electrocardiographic variables in differentiating types of tachycardia.

ANIMALS

Ninety-two dogs with orthodromic atrioventricular reciprocating tachycardia, 17 with atrial flutter, 33 with focal atrial tachycardia recorded and confirmed by electrophysiological study, and 40 dogs with sinus tachycardia.

METHODS

Atrial deflection position on the 12-lead surface electrocardiogram was assessed according to the sequence of intracardiac activation. Its features were evaluated together with the relationship between AD and QRS complex interval (AD-R) and QRS complex and AD interval (R-AD).

RESULTS

Orthodromic atrioventricular reciprocating tachycardia was characterized by an AD-AD interval of 213 ± 30 ms, mean electrical axis (MEA) of AD of -90 (-90/-78)°, R-AD interval of 75 (65-80) ms, and R-AD/AD-R of 0.54 (0.45-0.64). Atrial flutter was characterized by an AD-AD interval of 199 ± 57 ms, MEA of 76° (72/81), R-AD of 120 (72-144) ms, and R-AD/AD-R of 0.81 (0.63-1.13). Focal atrial tachycardia was characterized by an AD-AD interval of 270 ± 38 ms, MEA of 49 (-72/76)°, R-AD of 160 (120-200) ms, and R-AD/AD-R of 1.45 (0.92-1.67). Sinus tachycardia was characterized by an AD-AD interval of 292 ± 31 ms, MEA of 66° (52/73), R-AD of 215 (192-222) ms, and R-AD/AD-R of 2.68 (2.25-3.08).

CONCLUSIONS AND CLINICAL IMPORTANCE

Analyzing AD on 12-lead electrocardiogram is helpful in differentiating the most common SVTs in dogs.

Recognition of Supraventricular Arrhythmias in Holter ECG Recordings by ECHOView Color Map: A Case Series Study

Ambulatory 24-72 h Holter ECG monitoring is recommended for patients with suspected arrhythmias, which are often transitory and might remain unseen in resting standard 12-lead ECG. Holter manufacturers provide software diagnostic tools to assist clinicians in evaluating these large amounts of data. Nevertheless, the identification of short arrhythmia events and differentiation of the arrhythmia type might be a problem in limited Holter ECG leads. This observational clinical study aims to explore a novel and weakly investigated ECG modality integrated into a commercial diagnostic tool ECHOView (medilog DARWIN 2, Schiller AG, Switzerland), while used for the interpretation of long-term Holter-ECG records by a cardiologist. The ECHOView transformation maps the beat waveform amplitude to a color-coded bar. One ECHOView page integrates stacked color bars of about 1740 sequential beats aligned by R-peak in a window (R ± 750 ms). The collected 3-lead Holter ECG recordings from 86 patients had a valid duration of 21 h 20 min (19 h 30 min-22 h 45 min), median (quartile range). The ECG rhythm was reviewed with 3491 (3192-3723) standard-grid ECG pages and a substantially few number of 51 (44-59) ECHOView pages that validated the ECHOView compression ratio of 67 (59-74) times. Comments on the ECG rhythm and ECHOView characteristic patterns are provided for 14 examples representative of the most common rhythm disorders seen in our population, including supraventricular arrhythmias (supraventricular extrasystoles, paroxysmal supraventricular arrhythmia, sinus tachycardia, supraventricular tachycardia, atrial fibrillation, and flutter) and ventricular arrhythmias (ventricular extrasystoles, non-sustained ventricular tachycardia). In summary, the ECHOView color map transforms the ECG modality into a novel diagnostic image of the patient's rhythm that is comprehensively interpreted by a cardiologist. ECHOView has the potential to facilitate the manual overview of Holter ECG recordings, to visually identify short-term arrhythmia episodes, and to refine the diagnosis, especially in high-rate arrhythmias.

Identification of supraventricular tachycardia mechanisms with surface electrocardiograms using a convolutional neural network

Background

It remains difficult to definitively distinguish supraventricular tachycardia (SVT) mechanisms using a 12-lead electrocardiogram (ECG) alone. Machine learning may identify visually imperceptible changes on 12-lead ECGs and may improve ability to determine SVT mechanisms.

Objective

We sought to develop a convolutional neural network (CNN) that identifies the SVT mechanism according to the gold standard of SVT ablation and to compare CNN performance against experienced electrophysiologists among patients with atrioventricular nodal re-entrant tachycardia (AVNRT), atrioventricular reciprocating tachycardia (AVRT), and atrial tachycardia (AT).

Methods

All patients with 12-lead surface ECG during sinus rhythm and SVT and had successful SVT ablation from 2013 to 2020 were included. A CNN was trained using data from 1505 surface ECGs that were split into 1287 training and 218 test ECG datasets. We compared the CNN performance against independent adjudication by 2 experienced cardiac electrophysiologists on the test dataset.

Results

Our dataset comprised 1505 ECGs (368 AVNRT, 304 AVRT, 95 AT, and 738 sinus rhythm) from 725 patients. The CNN areas under the receiver-operating characteristic curve for AVNRT, AVRT, and AT were 0.909, 0.867, and 0.817, respectively. When fixing the specificity of the CNN to the electrophysiologist adjudicators' specificity, the CNN identified all SVT classes with higher sensitivity: (1) AVNRT (91.7% vs 65.9%), (2) AVRT (78.4% vs 63.6%), and (3) AT (61.5% vs 50.0%).

Conclusion

A CNN can be trained to differentiate SVT mechanisms from surface 12-lead ECGs with high overall performance, achieving similar performance to experienced electrophysiologists at fixed specificities.

Artificial intelligence-enabled electrocardiogram to distinguish atrioventricular re-entrant tachycardia from atrioventricular nodal re-entrant tachycardia

Background

Accurately determining arrhythmia mechanism from a 12-lead electrocardiogram (ECG) of supraventricular tachycardia can be challenging. We hypothesized a convolutional neural network (CNN) can be trained to classify atrioventricular re-entrant tachycardia (AVRT) vs atrioventricular nodal re-entrant tachycardia (AVNRT) from the 12-lead ECG, when using findings from the invasive electrophysiology (EP) study as the gold standard.

Methods

We trained a CNN on data from 124 patients undergoing EP studies with a final diagnosis of AVRT or AVNRT. A total of 4962 5-second 12-lead ECG segments were used for training. Each case was labeled AVRT or AVNRT based on the findings of the EP study. The model performance was evaluated against a hold-out test set of 31 patients and compared to an existing manual algorithm.

Results

The model had an accuracy of 77.4% in distinguishing between AVRT and AVNRT. The area under the receiver operating characteristic curve was 0.80. In comparison, the existing manual algorithm achieved an accuracy of 67.7% on the same test set. Saliency mapping demonstrated the network used the expected sections of the ECGs for diagnoses; these were the QRS complexes that may contain retrograde P waves.

Conclusion

We describe the first neural network trained to differentiate AVRT from AVNRT. Accurate diagnosis of arrhythmia mechanism from a 12-lead ECG could aid preprocedural counseling, consent, and procedure planning. The current accuracy from our neural network is modest but may be improved with a larger training dataset.

Electrocardiographic variables associated with underlying Brugada syndrome or drug-induced Type 1 Brugada pattern in patients with slow/fast atrioventricular nodal reentrant tachycardia

Background

The coexistence of clinical atrioventricular nodal reentrant tachycardia (AVNRT) and drug-induced type 1 Brugada pattern (DI-Type 1 BrP) has been previously reported. The present study was designed to determine the 12-lead ECG characteristics at baseline and during AVNRT and to identify a subset of 12-lead ECG variables of benefit associated with underlying Brugada syndrome (BrS)/DI-Type 1 BrP among patients with slow/fast AVNRT.

Methods

A total of 40 (11 numerical/29 categorical) 12-lead ECG parameters were analyzed and compared between patients with (n = 69) and without (n = 104) BrS/DI-Type1-BrP matched for age, female gender, body mass index, left ventricular ejection fraction and comorbid conditions. Five distinct types of ECG pattern (Type A/B/C/D/E) in V1-V2 leads during AVNRT were defined.

Results

A total of nine electrocardiographic variables, four at baseline, and five during AVNRT were identified. At baseline, patients with BrS/DI-Type 1 BrP had higher prevalence of interatrial block, leftward shift of frontal plane QRS axis, the absence of normal QRS pattern (the presence of rSr' pattern or type 2/3 Brugada pattern) in V1-V2 and QRS fragmentation in inferior leads compared to patients without BrS/DI-Type 1 BrP. During AVNRT, patients with BrS/DI-Type 1 BrP had higher prevalence of Type A ECG pattern ("coved-type" ST-segment elevation) in V1-V2, Type C ECG pattern (pseudo-r' deflection in V1 and "RBBB-like" pattern in V2), pseudo-r' deflection in V1, QRS fragmentation in inferior leads and "isolated" QRS fragmentation/notching/slurring in aVL compared to patients without BrS/DI-Type 1 BrP.

Conclusions

We identify several electrocardiographic variables that point to an underlying type 1 BrP among patients with slow/fast AVNRT.

Flexible Hybrid Electronics for Digital Healthcare

Recent advances in material innovation and structural design provide routes to flexible hybrid electronics that can combine the high-performance electrical properties of conventional wafer-based electronics with the ability to be stretched, bent, and twisted to arbitrary shapes, revolutionizing the transformation of traditional healthcare to digital healthcare. Here, material innovation and structural design for the preparation of flexible hybrid electronics are reviewed, a brief chronology of these advances is given, and biomedical applications in bioelectrical monitoring and stimulation, optical monitoring and treatment, acoustic imitation and monitoring, bionic touch, and body-fluid testing are described. In conclusion, some remarks on the challenges for future research of flexible hybrid electronics are presented.

Supraventricular tachycardia: An overview of diagnosis and management

Supraventricular tachycardia (SVT) is a common cause of hospital admissions and can cause significant patient discomfort and distress. The most common SVTs include atrioventricular nodal re-entrant tachycardia, atrioventricular re-entrant tachycardia and atrial tachycardia. In many cases, the underlying mechanism can be deduced from electrocardiography during tachycardia, comparing it with sinus rhythm, and assessing the onset and offset of tachycardia. Recent European Society of Cardiology guidelines continue to advocate the use of vagal manoeuvres and adenosine as first-line therapies in the acute diagnosis and management of SVT. Alternative therapies include the use of beta-blockers and calcium channel blockers. All patients treated for SVT should be referred for a heart rhythm specialist opinion. Long-term treatment is dependent on several factors including frequency of symptoms, risk stratification, and patient preference. Management can range from conservative, if symptoms are rare and the patient is low risk, to catheter ablation which is curative in the majority of patients.

A new criterion to differentiate atrioventricular nodal reentrant tachycardia from atrioventricular reciprocating tachycardia: Combined AVR criterion

AIM

A combined aVR criterion is described as the presence of a pseudo r' wave in aVR during tachycardia in patients without r' wave in aVR in sinus rhythm and/or a ≥50% increase in r' wave amplitude compared to sinus rhythm in patients with r' wave in the basal aVR lead. We aimed to investigate the use of combined aVR criterion in differential diagnosis of atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT).

METHODS

In this prospective study, 480 patients with inducible narrow QRS supraventricular tachycardia (SVT) were included. Twelve-lead electrocardiogram (ECG) was conducted during tachycardia and sinus rhythm. The patients were divided into two groups according to the arrhythmia mechanism that determined via EPS, AVNRT, and AVRT. Criteria of narrow QRS complex tachycardia were compared between the two groups.

RESULTS

AVNRT was present in 370 (77%) patients and AVRT in 110 (23%) patients. Combined aVR criterion was found to be more frequent in patients with AVNRT (84.1% and 9.1%, p < 0.001). In logistic regression analysis, combined aVR criterion and classical ECG criterion were found to be the most important predictors of AVNRT (p < 0.001). The sensitivity, specificity, positive predictive value, and negative predictive value of the combined aVR criterion for AVNRT were 84.1%, 90.9%, 96.9%, and 62.9%, respectively.

CONCLUSION

In the differential diagnosis of patients with SVT, the combined aVR criterion identifies the presence of AVNRT with an independent and acceptable diagnostic value. In addition to classical ECG criteria for AVNRT, it is necessary to evaluate the combined aVR criterion in daily practice.

Supraventricular Arrhythmias: Clinical Framework and Common Scenarios for the Internist

Supraventricular arrhythmias can cause uncomfortable symptoms for patients. Often, the first point of contact is in the primary care setting, and thus, it is imperative for the general internist to have a clinical framework in place to recognize this cluster of cardiac arrhythmias, be familiar with immediate and long-term management of supraventricular tachycardias, and understand when cardiac electrophysiologic consultation is necessary. The electrocardiographic characteristics can have subtle but important clues to the diagnosis and initial management. An understanding of the mechanisms of these arrhythmias is essential to provide proper therapy to the patient. In addition, there are common practice strategies that should be emphasized to avoid common misperceptions that could pose risk to the patient. In this review, we provide a framework to more easily recognize and classify these arrhythmias. We also illustrate the mechanism for these arrhythmias to provide an understanding of the interventions generally used.

Diagnostic Accuracy of Several Electrocardiographic Criteria for the Prediction of Atrioventricular Nodal Reentrant Tachycardia

BACKGROUND AND AIMS

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal supraventricular tachycardia (SVT) whose diagnosis can be strongly suspected based on the surface eletrocardiogram alone. The purpose of this study is to determine the diagnostic accuracy of several electrocardiographic (ECG) criteria for the prediction of AVNRT.

METHODS

Between November 2010 and January 2014, a total of 256 patients who underwent electrophysiological testing (EP) with regular, paroxysmal and narrow QRS complex tachycardia were prospectively enrolled. We classified the ECG recordings during tachycardia for the presence of the following criteria: a) classical ECG findings of pseudo S wave in inferior leads and/or pseudo r' wave in lead V1, b) notch in lead aVL, c) no retrograde P waves visible during tachycardia; d) pseudo r' wave in lead aVR, e) notch in lead D1, f) any deflection after 100 ms of the QRS complex during tachycardia.

RESULTS

On multivariate analysis, independent predictors of AVNRT diagnosis were female sex (OR 4.17; 95% CI [2.11-8.24]; p <0.001), age >60 years (OR 3.53; 95% CI [1.25-9.96]; p = 0.017) and the classical ECG criteria (OR 7.41; 95% CI [3.62-15.17]; p <0.001).

CONCLUSIONS

Female, age >60 years and the classical ECG criteria were the independent predictors of AVNRT diagnosis. Although several of the ECG criteria for AVNRT diagnosis showed acceptable sensitivities and specificities, they do not improve its accuracy.

Differentiation of Slow-Slow Form of AVNRT from AVRT through a Posteroseptal Accessory Pathway by Retrograde P-Wave Amplitude

BACKGROUND

This study aimed to clarify whether retrograde P-wave amplitude during tachycardia can be used to differentiate slow-slow form of atrioventricular nodal reentrant tachycardia (S/S-AVNRT) from atrioventricular reentrant tachycardia through a posteroseptal accessory pathway (PS-AVRT).

METHODS

Sixteen patients with S/S-AVNRT and 14 patients with PS-AVRT constituted the study group. Electrocardiographic and electrophysiological parameters were compared between both the groups. HA(CS-His), which indicates the location of the earliest atrial activation site during tachycardia, was calculated as the difference of the shortest HA interval in the His bundle region and the coronary sinus region.

RESULTS

Negative deflection of the retrograde P wave during tachycardia was significantly greater in S/S-AVNRT than in PS-AVRT in the inferior leads (lead aVF, -0.22 ± 0.04 mV vs -0.10 ± 0.07 mV; P < 0.001). Among the electrocardiographic parameters, retrograde P-wave amplitude in lead aVF had the highest diagnostic accuracy (area under the curve 0.975, sensitivity 93%, and specificity 88% for a cutoff value of -0.16 mV). HA(CS-His) was negatively greater in S/S-AVNRT than in PS-AVRT (-24 ± 13 ms vs -3 ± 18 ms; P = 0.001), and was significantly correlated with the retrograde P-wave amplitude in lead aVF (P = 0.004).

CONCLUSION

Deeper negative deflection of the retrograde P wave in the inferior lead can help differentiate S/S-AVNRT from PS-AVRT.

Validation of Standard and New Criteria for the Differential Diagnosis of Narrow QRS Tachycardia in Children and Adolescents

To establish an appropriate treatment strategy and determine if ablation is indicated for patients with narrow QRS complex supraventricular tachycardia (SVT), analysis of a standard 12-lead electrocardiogram (ECG) is required, which can differentiate between the 2 most common mechanisms underlying SVT: atrioventricular nodal reentry tachycardia (AVNRT) and orthodromic atrioventricular reentry tachycardia (OAVRT). Recently, new, highly accurate electrocardiographic criteria for the differential diagnosis of SVT in adults were proposed; however, those criteria have not yet been validated in a pediatric population.All ECGs were recorded during invasive electrophysiology study of pediatric patients (n = 212; age: 13.2 ± 3.5, range: 1-18; girls: 48%). We assessed the diagnostic value of the 2 new and 7 standard criteria for differentiating AVNRT from OAVRT in a pediatric population.Two of the standard criteria were found significantly more often in ECGs from the OAVRT group than from the AVNRT group (retrograde P waves [63% vs 11%, P < 0.001] and ST-segment depression in the II, III, aVF, V1-V6 leads [42% vs 27%; P < 0.05]), whereas 1 standard criterion was found significantly more often in ECGs from the AVNRT group than from the OAVRT group (pseudo r' wave in V1 lead [39% vs 10%, P < 0.001]). The remaining 6 criteria did not reach statistical significance for differentiating SVT, and the accuracy of prediction did not exceed 70%. Based on these results, a multivariable decision rule to evaluate differential diagnosis of SVT was performed.These results indicate that both the standard and new electrocardiographic criteria for discriminating between AVNRT and OAVRT have lower diagnostic values in children and adolescents than in adults. A decision model based on 5 simple clinical and ECG parameters may predict a final diagnosis with better accuracy.

A Smartphone Application to Diagnose the Mechanism of Pediatric Supraventricular Tachycardia

Smartphone applications that record a single-lead ECG are increasingly available. We sought to determine the utility of a smartphone application (AliveCor) to record supraventricular tachycardia (SVT) and to distinguish atrioventricular reentrant tachycardia (AVRT) from atrioventricular nodal reentrant tachycardia (AVNRT) in pediatric patients. A prior study demonstrated that interpretation of standard event and Holter monitors accurately identifies the tachycardia mechanism in only 45 % of recordings. We performed an IRB-approved prospective study in pediatric patients undergoing an ablation for SVT. Tracings were obtained by placing the smartphone in three different positions on the chest (PI-horizontal, PII-rotated 60° clockwise, and PIII-rotated 120° clockwise). Two blinded pediatric electrophysiologists jointly analyzed a pair of sinus and tachycardia tracings in each position. Tracings with visible retrograde P waves were classified as AVRT. The three positions were compared by Chi-square test. Thirty-seven patients (age 13.7 ± 2.8 years) were enrolled in the study. Twenty-four had AVRT, and 13 had AVNRT. One hundred and eight pairs of tracings were obtained. The correct diagnosis was made in 27/37 (73 %) with position PI, 28/37 (76 %) with PII, and 20/34 (59 %) with PIII (p = 0.04 for PII vs. PIII and p = NS for other comparisons). A single-lead ECG obtained with a smartphone monitor can successfully record SVT in pediatric patients and can predict the SVT mechanism at least as well as previously published reports of Holter monitors, along with the added convenience of not requiring patients to carry a dedicated monitor.

High prevalence of concealed Brugada syndrome in patients with atrioventricular nodal reentrant tachycardia

BACKGROUND

Atrioventricular nodal reentrant tachycardia (AVNRT) may coexist with Brugada syndrome (BrS).

OBJECTIVES

The present study was designed to determine the prevalence of drug-induced type 1 Brugada ECG pattern (concealed BrS) in patients presenting with clinical spontaneous AVNRT and to investigate their electrocardiographic, electrophysiological, and genetic characteristics.

METHODS

Ninety-six consecutive patients without any sign of BrS on baseline electrocardiogram undergoing electrophysiological study and ablation for symptomatic, drug-resistant AVNRT and 66 control subjects underwent an ajmaline challenge to unmask BrS. Genetic screening was performed in 17 patients displaying both AVNRT and BrS.

RESULTS

A concealed BrS electrocardiogram was uncovered in 26 of 96 patients with AVNRT (27.1%) and in 3 of 66 control subjects (4.5%) (P ≤ .001). Patients with concealed BrS were predominantly female patients (n=23 [88.5%] vs n=44 [62.9%], P = .015), had higher prevalence of chest pain (n=10 [38.5%] vs n=13 [18.6%], p=0.042), migraine headaches (n=10 [38.5%] vs n=10 [14.2%], p=0.008), and drug-induced initiation and/or worsening of duration and/or frequency of AVNRT (n=4 [15.4%] vs n=1 [1.4%], p=0.006) as compared to patients with AVNRT without BrS. Genetic screening identified 19 mutations or rare variants in 13 genes in 13 of 17 patients with both AVNRT and BrS (yield = 76.5%). Ten of these 13 genotype-positive patients (76.9%) harbored genetic variants known or suspected to cause a loss of function of cardiac sodium channel current (SCN5A, SCN10A, SCN1B, GPD1L, PKP2, and HEY2).

CONCLUSION

Our results suggest that spontaneous AVNRT and concealed BrS co-occur, particularly in female patients, and that genetic variants that reduce sodium channel current may provide a mechanistic link between AVNRT and BrS and predispose to expression of both phenotypes.

U wave during supraventricular tachycardia: simulation of a long RP tachycardia and hiding the common type AVNRT

The main tool for the differentiation of supraventricular tachycardia is the 12-lead electrocardiogram (ECG). Especially differentiating the atrioventricular nodal reentrant tachycardia (AVNRT) from the atrioventricular reentrant tachycardia (AVRT) due to concealed accessory pathway or from an atrial tachycardia (AT) is very important for catheter setting and ablation approach in an electrophysiological study. In our case we saw the occurrence of a U wave during tachycardia-simulating a pseudo P wave. This mimicked a long RP-tachycardia, although it was a common type AVNRT.

Atrial tachycardia mimicking atrioventricular nodal reentry tachycardia

BACKGROUND

The term supraventricular tachycardia (SVT) is used to describe tachydysrhythmias that require atrial or atrioventricular nodal tissue for their initiation and maintenance. SVT can be used to describe atrioventricular nodal reentry tachycardia, atrioventricular reentry tachycardia, and atrial tachycardia (AT). AT is the least common of these SVT subtypes, accounting for only 10% of cases. Although the suggested initial management of each SVT subtype is different, they all can present with similar symptoms and electrocardiographic findings.

OBJECTIVE

Discuss the pathophysiology, diagnosis, and treatment of AT as compared with other types of SVT.

CASE REPORT

We report a 56-year-old woman with symptoms and electrocardiographic findings consistent with SVT. Although standard treatment with intravenous adenosine failed to convert the SVT, it revealed AT as the cause of the tachydysrhythmia. The AT was successfully terminated with beta-blockade and the patient eventually underwent successful radioablation of three separate AT foci.

CONCLUSIONS

AT frequently mimics other more common forms of SVT. AT might be recognized only when standard treatment of SVT has failed. Identification of AT in this setting is crucial to allow for more definitive therapy.

Supraventricular tachycardias: proposal of a diagnostic algorithm for the narrow complex tachycardias

The narrow complex tachycardias (NCTs) are defined by the presence in a 12-lead electrocardiogram (ECG) of a QRS complex duration less than 120ms and a heart rate greater than 100 beats per minute; those are typically of supraventricular origin, although rarely narrow complex ventricular tachycardias have been reported in the literature. As some studies document, to diagnose correctly the NCTs is an arduous exercise because sometimes those have similar presentation on the ECG. In this paper, we have reviewed the physiopathological, clinical, and ECG findings of all known supraventricular tachycardias and, in order to reduce the possible diagnostic errors on the ECG, we have proposed a quick and accurate diagnostic algorithm for the differential diagnosis of NCTs.

EGC diagnosis of paroxysmal supraventricular tachycardias in patients without preexcitation

This review is aimed at discussing the diagnostic value of the different electrocardiographic criteria so far described in the differential diagnosis of the major forms of paroxysmal supraventricular tachycardias (PSVTs). The predictive value of different combinations of these independent electrocardiographic (ECG) signs in distinguishing atrioventricular reentrant tachycardias (AVRTs) through a concealed accessory pathway (AP) versus atrioventricular nodal reentrant tachycardias (AVNRTs) are discussed in detail. In addition, the adjunctive diagnostic value of simple, bedside clinical variables and their combinations to the ECG interpretation in differentiating both tachycardia mechanisms is also reviewed.

A new method of filtering T waves to detect hidden P waves in electrocardiogram signals

AIMS

A correct identification of the P wave is crucial for the diagnosis of narrow QRS tachycardias. This is sometimes difficult because atrial activity is hidden in the T wave. The aim of this study is to evaluate the usefulness of a T wave filtering technique based on wavelet transformation to identify atrial activity.

METHODS AND RESULTS

Forty-two patients with narrow QRS tachycardias and regular atrial activity were studied. A surface electrocardiogram (ECG), intra-atrial recording, and the T wave filtering ECG were compared simultaneously to check the accuracy of the filtering system in detecting atrial activity. The sensitivity of the T wave filtering and P wave detection algorithm was 85.8% [95% confidence interval (CI): 81.2-89.4%] and the specificity was 89.4% (95% CI: 87.1-91.4%), with a global accuracy of 88.5% (95% CI: 86.5-90.3%). The expert cardiologist's accuracy in distinguishing between atrioventricular nodal reentry tachycardia and atrioventricular reentry tachycardia was 75% in the surface ECG vs. 100% in the ECG with the T wave filtering process (P<0.01).

CONCLUSIONS

T wave filtering based on wavelet transformation improves the capacity of the surface ECG to identify atrial activity in cases of regular narrow QRS supraventricular tachycardias.

Supraventricular tachycardia: diagnosis and management

Supraventricular tachycardia (SVT) includes all forms of tachycardia that either arise above the bifurcation of the bundle of His or that have mechanisms dependent on the bundle of His. We conducted a review of the techniques used to differentiate the mechanisms of SVT. We searched the PubMed and MEDLINE databases for English-language literature published from 1970 to 2008. Articles were selected for either their historical importance or up-to-date clinical data. This review focuses on techniques for scrutinizing electrocardiograms of patients, analyzing in particular the onset of tachycardia, the mode of tachycardia termination, and the effects of premature ventricular contractions, premature atrial contractions, and aberrancy during tachycardia. Both short-term and long-term management of SVT are examined, including the urgent treatment of patients in the emergency department. This review also describes management of patients who have ongoing symptomatic SVT, outlining such available treatment options as atrioventricular node-blocking drugs, antiarrhythmic drugs, and catheter ablation.

A modified electrocardiographic algorithm for differentiating typical atrioventricular node re-entrant tachycardia from atrioventricular reciprocating tachycardia mediated by concealed accessory pathway

Non-invasive prediction of tachycardia mechanism is becoming clinically important in the era of catheter ablation for curing supraventricular tachycardia. Twelve-lead electrocardiograms (ECGs) during sinus rhythm and atrioventricular node re-entrant tachycardia (AVNRT) or atrioventricular reciprocating tachycardia (AVRT) with a narrow QRS complex were obtained from 154 consecutive adult patients who had received successful radiofrequency catheter ablation. The ECGs of initial 104 patients were analysed by three observers without knowledge of the electrophysiological diagnosis. The two arrhythmias were accurately diagnosed in 68% of cases. Three criteria were found to be discriminators of tachycardia mechanism by univariable analysis. Pseudo r/Q/S waves predicated AVNRT in 92% of cases (sensitivity 71%; specificity 95%). Retrograde P wave predicated AVRT in 86% of cases (sensitivity 75%; specificity 85%), RP interval > or =100 ms in 93% (sensitivity 71%; specificity 94%) and ST-segment elevation in lead aVR in 83% (sensitivity 71%; specficity 83%). According to the initial results, we proposed a modified stepwise ECG algorithm which used pseudo r/S/Q waves, RP interval and ST-segment elevation in lead aVR during tachycardia. Two observers assessed the modified algorithm in the remaining 50 patients. The algorithm was able to correctly diagnose the tachycardia mechanism in 84% and 87%, respectively. Using the modified algorithm can improve the accuracy and simplify the differential diagnosis between typical AVNRT and AVRT via concealed accessory pathway in adult patients.

Differentiation of narrow QRS complex tachycardia types using the 12-lead electrocardiogram

BACKGROUND

Previous studies have shown that only 80% of narrow QRS supraventricular tachycardia (SVT) types can be differentiated by standard 12-lead electrocardiographic (ECG) criteria. This study was designed to determine the value of some new ECG criteria in differentiating narrow QRS SVT.

METHODS AND RESULTS

120 ECGs demonstrating paroxysmal narrow QRS complex tachycardia (QRS < or = 0.11 ms and rate > 120 beats/min) were analyzed. Forty atrioventricular reciprocating tachycardia (AVRT), 70 atrioventricular nodal reentrant tachycardia (AVNRT), and 10 atrial tachycardia defined with electrophysiologic study (EPS) consisted the study group. Eight surface ECG criteria were found to be significantly different between tachycardia types by univariate analysis. P waves separate from the QRS complex were observed more frequently in AVRT (70%) and atrial tachycardia (80%). Pseudo r' deflection in lead V(1), pseudo S wave in inferior leads, and cycle length alternans were more common in AVNRT (55, 20, and 6%, respectively). QRS alternans was also present during AVRT (28%). ST-segment depression (> or = 2 mm) or T-wave inversion, or both, were present more often in AVRT (60%) than in AVNRT (27%). During sinus rhythm, manifest preexcitation was observed more often in patients with AVRT (42%). When a P wave was present, RP/PR interval ratio > 1 was more common in atrial tachycardia (90%). By multivariate analysis, presence of a P wave separate from the QRS complex, pseudo r' deflection in lead V(1), QRS alternans, preexcitation during sinus rhythm, ST-segment depression > 2 mm or T-wave inversion, or both, were independent predictors of tachycardia type.

CONCLUSIONS

Several new ECG criteria may be useful in differentiation of SVT types. Prediction of mechanism prior to EPS may provide additional benefits concerning the fluoroscopic exposure time and cardiac catheterization procedure.

The 12-lead electrocardiogram in supraventricular tachycardia

The 12-lead electrocardiogram (ECG) is an invaluable tool for the diagnosis of supraventricular tachycardia (SVT). Most forms of SVT can be distinguished with a high degree of certainty based on specific ECG characteristics by using a systematic, stepwise approach. This article provides a general framework with which to approach an ECG during SVT by describing the salient characteristics, ECG findings, and underlying electroanatomical relationships of each specific type of SVT encountered in adults. It concludes by providing a systematic algorithm for diagnosing SVT based on the findings of the 12-lead ECG.

Tachydysrhythmias

Tachydysrhythmias arise from different mechanisms that can be characterized as being caused by re-entrant circuits, enhanced or abnormal automaticity, or triggered after-depolarizations. The approach to the tachydysrhythmia should begin with distinguishing sinus from non-sinus rhythms, then assessing QRS complex width and regularity. This article review tachydysrhythmias.

Differentiating atrioventricular nodal reentrant tachycardia from tachycardia via concealed accessory pathway

Studies analyzing the diagnostic value of 12-lead electrocardiographic criteria differentiating slow-fast atrioventricular nodal reentrant tachycardia (AVNRT) from atrioventricular reentrant tachycardia (AVRT) due to concealed accessory pathway have shown inconsistent results. In 97 patients (50 with AVNRT, 47 with AVRT) 12-lead electrocardiograms (ECGs) were recorded during sinus rhythm and tachycardia (QRS <120 ms). The ECGs were blinded for diagnosis and patient and analyzed independently by 2 electrophysiologists. The studied criteria differentiating AVNRT from AVRT included pseudo-r'/S, the presence of a retrograde P wave, RP interval, ST-segment depression >/=2 mm with the number and location of the affected leads, QRS amplitude, and cycle length alternans.

Differential Diagnosis of Slow/Slow Atrioventricular Nodal Reentrant Tachycardia from Atrioventricular Reentrant Tachycardia Using Concealed Posteroseptal Accessory Pathway by 12-Lead Electrocardiography

Slow pathways are used as both antegrade and retrograde conduction pathway in slow/slow atrioventricular nodal reentrant tachycardia (SS-AVNRT), and patients with SS-AVNRT have tachycardia ECGs mimicking atrioventricular reentrant tachycardia using concealed posteroseptal accessory pathway (PS-AVRT). Therefore, SS-AVNRT can be misdiagnosed as PS-AVRT, and the differential diagnosis is clinically important. Standard 12-lead ECGs during tachycardia were analyzed in patients with SS-AVNRT (n = 10) and PS-AVRT (n = 10). All these patients were diagnosed by electrophysiological study and underwent successful catheter ablation. Differences of the RP' intervals (dRP') between V1 and the inferior leads were evaluated. SS-AVNRT had significantly longer RP' intervals measured in V1 (167 +/- 25.2 vs 137 +/- 26.8 ms, SS-AVNRT vs PS-AVRT, respectively, P = 0.02), longer dRP' between V1 and II (dRP'[V1-II], 37 +/- 14 vs 17 +/- 6.7 ms, P = 0.0007), longer dRP'[V1-III] (39 +/- 14 vs 17 +/- 9.9 ms, P = 0.0011), and longer dRP'[V1-aVF] (39 +/- 13 vs 20 +/- 9.5 ms, P = 0.0008). The following criteria were suggested for differential diagnosis of SS-AVNRT from PS-AVRT: dRP'[V1-II] >25 ms (sensitivity and specificity: 80% and 100%, respectively), dRP'[V1-III] >23 ms (90% and 90%), dRP'[V1-aVF] >30 ms (90% and 90%). Differences of the RP' intervals between V1 and the inferior leads in the tachycardia ECGs were useful for differential diagnosis of SS-AVNRT from PS-AVRT.

Electrocardiographic differentiation of typical atrioventricular node reentrant tachycardia from atrioventricular reciprocating tachycardia mediated by concealed accessory pathway in children

The value of the electrocardiogram (ECG) in children with supraventricular tachycardia (SVT) is unclear. The noninvasive differentiation of typical atrioventricular node reentrant tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT) mediated by concealed accessory pathway conduction is clinically important, as it helps in counseling and potentially facilitates ablation procedures. One hundred forty-eight ECGs showing narrow QRS complex SVT were obtained from children before successful radiofrequency catheter ablation. An initial 102 ECGs were analyzed by 3 blinded observers to assess the utility of various electrocardiographic findings. No electrocardiographic criteria were found to discriminate between SVT mechanisms on 1- to 3-channel Holter/event recorder tracings (n = 32); their interpretation mainly (55%) resulted in an incorrect SVT diagnosis. On 12-lead ECGs (n = 70), the 2 arrhythmias were accurately diagnosed in 76% of patients; 5 findings were found to be discriminators of tachycardia mechanism. Predictors of AVRT were visible P waves in 74% of cases (sensitivity 92%; specificity 64%), RP intervals of > or =100 ms in 91% (sensitivity 84%; specificity 91%), and ST-segment depression of > or =2 mm in 73% of cases (sensitivity 52%; specificity 82%). Pseudo r' waves in lead V(1) and pseudo S waves in the inferior leads during tachycardia predicted AVNRT in 100% of cases (sensitivity 55% and 20%, respectively; specificity 100% for both). Based on these results, we developed a new diagnostic 12-lead electrocardiographic algorithm for pseudo r'/S waves, RP duration, and ST-segment depression during tachycardia. Two observers tested the algorithm in 46 (21 AVNRT; 25 AVRT) additional cases; they correctly diagnosed the SVT mechanism in 91% and 87%, respectively. Thus, the stepwise use of diagnostically relevant 12-lead electrocardiographic parameters helps to more accurately differentiate mechanisms of reentrant SVT.

Testing of a new T-wave subtraction algorithm as an aid to localizing ectopic atrial beats

BACKGROUND

Identifying the timing and morphology of an ectopic P wave from the surface electrogram can aid in the diagnosis and localization of atrial arrhythmias. Given the relatively short coupling interval of atrial ectopic beats, the P wave is often obscured by the larger amplitude QRS-T wave complex. A method to uncover such "buried" P waves using a standard 12-lead surface ECG would be clinically useful and could potentially be a noninvasive guide to catheter ablation of focal atrial tachycardia.

METHODS

We developed an automated computerized program (BARD DUO LAB SYSTEM trade mark ) designed to subtract the QRS-T wave complex from the surface electrogram and uncover a previously obscured P wave. The purpose of the present study was to validate this program. The surface ECG from 21 patients undergoing atrial pacing during electrophysiologic study (group I) and 10 patients with atrial tachycardia (group II) were analyzed and the derived P-wave morphology assessed using correlation waveform analysis (CWA) and visual grading by three reviewers.

RESULTS

The algorithm successfully uncovered the P wave in each surface ECG. For the 21 patients in group I, average CWA comparing the derived P wave with the previous paced P wave was 83%. Average CWA for group II was 82%. Visual grading of the match between derived P waves and paced P waves revealed a 21/21 match in group I patients and a 12/12 match in 9/10 of group II patients.

CONCLUSIONS

An ectopic atrial P wave obscured by a coincident QRS-T wave complex can be accurately uncovered using this new algorithm. Addition of this technique to existing methods may improve the diagnosis of atrial arrhythmias and aid in the localization and ablation of ectopic atrial foci.

Electrocardiographic manifestations: narrow QRS complex tachycardias

Narrow QRS complex tachycardia is a common dysrhythmia in Emergency Medicine practice. Diagnosis and mechanism often can be made by 12-lead electrocardiographic (EKG) analysis but may subsequently require electrophysiologic testing. The clinical manifestations are varied and dependent upon heart rate, prior cardiac disease, and general physiologic status. Patient management is directed towards the etiology and mechanism of the dysrhythmia and includes vagal maneuvers, pharmacologic therapy, and cardioversion. Hemodynamically compromised patients must be promptly treated. Patients are often admitted to the hospital but selected patients can be safely discharged from the Emergency Department for outpatient evaluation and management. Pediatric and pregnant patients are, in general, treated the same as adults. Several case examples and EKGs are presented.

Atrial components contributing to pseudo r' deflection in lead V1 in slow/fast atrioventricular nodal reentrant tachycardia: analysis of the atrial activation sequence by basket catheter isochronal mapping

Electrocardiographic recognition of the P' wave during tachycardia is very useful in the diagnosis of supraventricular tachycardias. In slow/fast (S/F) atrioventricular nodal reentrant tachycardia (AVNRT), no discrete P' waves are observed on ECG and pseudo r' deflection in lead V1 (pseudo r') is commonly recognized. However, the atrial components that contribute to the genesis of pseudo r' in lead V1 have not been described and this study aimed to clarify them by analysis of the whole activation sequence of the right atrium using Basket catheter isochronal mapping. The study group comprised 48 patients with AVNRT. Pseudo r' was defined as an upward deflection in the terminal portion of the QRS complex during tachycardia that was not recognized during sinus rhythm and it occurred in 45 patients (94%). During S/F AVNRT, the retrograde atrial activation was earliest on His bundle electrogram, followed by the coronary sinus ostium, distal coronary sinus and high right atrium. Only the high lateral aspect of the right atrium was activated after the end of the QRS complex. The interval between the onset of QRS in multiple surface ECG leads and the atrial activities on high right atrium was similar to the V-r' interval in lead V1 (111+/-20ms, 117+/-11 ms) and correlated with the V-r' interval (r=0.56). Pseudo r' deflection in lead V1 is a highly sensitive indicator of S/F AVNRT, and appears to result from the activation of the superolateral aspect of the right atrium.

Supraventricular tachycardia

Supraventricular tachycardias (SVT) comprise those tachycardias that originate above the bifurcation of the bundle of His. They can be classified broadly as AV node dependent and AV node independent. The mechanism and clinical manifestation of SVTs, which is essential to their correct diagnosis, is reviewed. The therapeutic management of SVTs, including acute and chronic drug therapy and catheter ablation, is discussed also.

Efficacy and safety of out-of-hospital self-administered single-dose oral drug treatment in the management of infrequent, well-tolerated paroxysmal supraventricular tachycardia

OBJECTIVES

We tested the efficacy of two drug treatments, flecainide (F) and the combination ofdiltiazem and propranolol (D/P), administered as a single oral dose for termination of the arrhythmic episodes.

BACKGROUND

Both prophylactic drug therapy and catheter ablation are questionable as first-line treatments in patients with infrequent and well-tolerated episodes of paroxysmal supraventricular tachycardia (SVT).

METHODS

Among 42 eligible patients (13% of all screened for SVT) with infrequent (< or =5/year), well-tolerated and long-lasting episodes, 37 were enrolled and 33 had SVT inducible during electrophysiological study. In the latter, three treatments (placebo, F, and D/P) were administered in a random order 5 min after SVT induction on three different days.

RESULTS

Conversion to sinus rhythm occurred within 2 h in 52%, 61%, and 94% of patients on placebo, F and D/P, respectively (p < 0.001). The conversion time was shorter after D/P (32 +/- 22 min) than after placebo (77 +/- 42 min, p < 0.001) or F (74 +/- 37 min, p < 0.001). Four patients (1 placebo, 1 D/P, and 2 F) had hypotension and four (3 D/P and 1 F) a sinus rate <50 beats/min following SVT interruption. Patients were discharged on a single oral dose of the most effective drug treatment (F or D/P) at time of acute testing. Twenty-six patients were discharged on D/P and five on F. During 17 +/- 12 months follow-up, the treatment was successful in 81% of D/P patients and in 80% of F patients, as all the arrhythmic episodes were interrupted out-of-hospital within 2 h. In the remaining patients, a failure occurred during one or more episodes because of drug ineffectiveness or drug unavailability. One patient had syncope after D/P ingestion. During follow-up, the percentage of patients calling for emergency room assistance was significantly reduced as compared to the year before enrollment (9% vs. 100%, p < 0.0001).

CONCLUSIONS

The episodic treatment with oral D/P and F, as assessed during acute testing, appears effective in the management of selected patients with SVT. This therapeutic strategy minimizes the need for emergency room admissions during tachycardia recurrences.

Supraventricular Tachyarrhythmia

The main treatment modalities for supraventricular tachycardia are medications and catheter ablation. Ablation is appropriate therapy for paroxysmal supraventricular tachycardia in patients who have a preference for ablation over medications, symptoms that are refractory to medications, severe symptoms, Wolff-Parkinson-White syndrome, or incessant tachycardia. Ablation also is reasonable as first-line therapy in patients with recurrent typical atrial flutter.

Significance of newly acquired negative T waves after interruption of paroxysmal reentrant supraventricular tachycardia with narrow QRS complex

Sixty-three patients with paroxysmal supraventricular tachycardia were studied and 25 patients (39%) showed newly acquired negative T waves after tachycardia termination. Silent coronary artery disease could not be found in about 90% of these patients; moreover, age, sex, organic heart disease, and tachycardia duration and rate did not predict the appearance of negative T waves.