Journal of Electrocardiology - Articles in Press

A Web-based tool for processing and visualizing body surface potential maps - Corrected Proof

Raymond R. Bond, Dewar D. Finlay, Chris D. Nugent, George Moore — 2010-07-23

Abstract: The body surface potential map (BSPM) is potentially more accurate for diagnosing cardiac pathologies when compared to the standard 12-lead electrocardiogram (ECG). However, a contributing factor to the lack of widespread adoption of the BSPM is the shortage of standard methods for its storage and visualization. Based on these observations, a BSPM storage format based on the eXtensible Markup Language has been developed within this study, alongside a Web-based BSPM viewer. This viewer was created using a lossless vector graphics tool (Adobe Flash) to maintain the quality of the ECG waveforms when they are enlarged. The viewer also runs inside the Web browser to facilitate BSPM visualization independent of the clinician's geographical location. This online nature enabled the creation of a comments system that can be used to assist in a collaborative diagnosis. This is useful because BSPM diagnostic criteria are not well established. Moreover, using the viewer's innovative tools (ie, calipers, isopotential maps), the clinician can explore BSPM datasets. Algorithms have also been integrated within the system to extract and display the 12-lead ECG and the vectorcardiogram from the BSPM. This viewer has been available online for 10 months alongside a Weblog, which has been used to record the user's feedback. During this period, 12 experts from both the clinical and visualization domains evaluated the viewer and contributed to its design. It has been the general consensus of all experts that the application is an effective solution for visualizing BSPMs. This viewer has been tested to visualize 2 different BSPMs using a PC (3 GHz CPU, 3 GB RAM, 6 MB broadband). The Lux-192 BSPM and the Kornreich-117 BSPM where both uploaded and visualized within 3.8 seconds (mean time from 10 trials). This BSPM storage format and its associated viewer provide a framework for a BSPM management system. If this system is made widely available, it has the potential to provide BSPM interoperability, knowledge sharing, and standardization. This has the potential to increase the uptake of BSPM integration into routine clinical practice.

Lability of R- and T-wave peaks in three-dimensional electrocardiograms in implantable cardioverter defibrillator patients with ventricular tachyarrhythmia during follow-up - Corrected Proof

Lichy Han, Larisa G. Tereshchenko — 2010-07-23

Abstract: Introduction: From experiments, we know that the heterogeneity of action potential duration and morphology is an important mechanism of ventricular tachyarrhythmia. Electrocardiogram (ECG) markers of repolarization lability are known; however, lability of depolarization has not been systematically studied. We propose a novel method for the assessment of variability of both depolarization and repolarization phases of the cardiac cycle.Methods: Baseline orthogonal ECGs of 81 patients (mean ± SD age, 56 ± 13 years; 61 male [75%]) with structural heart disease and implanted single-chamber implantable cardioverter defibrillator (ICD) were analyzed. Clean 30-beat intervals with absence of premature beats were then selected. Baseline wandering was corrected before analysis. Peaks of R wave and peaks of T wave were detected for each beat, and the axis magnitude was calculated. The peaks were plotted to show clouds of peaks and then used to construct a convex hull, and the volumes of the R peaks cloud and T peaks cloud and ratio of volumes were calculated.Results: During a mean (SD) follow-up period of 13 (10) months, 9 of the 81 patients had sustained ventricular tachycardia or ventricular fibrillation (VT/VF) and received appropriate ICD therapies. All ICD events were adjudicated by three independent electrophysiologists. There was no statistically significant difference in the volume of T-wave peaks or R-wave peaks between patients with and without VT or VF during follow-up; however, R/T peaks cloud volume ratio was significantly lower in patients with subsequent VT/VF (22.4 ± 25.4 versus 13.1 ± 7.9, P = .024).Conclusions: Larger volume of T peaks cloud, measured during 30 beats of three-dimensional ECG, is associated with higher risk of sustained ventricular tachyarrhythmias and appropriate ICD therapies. New method to assess temporal variability of repolarization in three-dimensional ECGs by measuring volume of peak clouds shows potential for further exploration for VT/VF risk stratification.

Low-voltage electrocardiogram in a comatose patient after endoscopic retrograde cholangiopancreatography - Corrected Proof

Claudia Stöllberger, Josef Finsterer — 2010-07-23

Abstract: A 59-year-old female became comateuse after endocscopic retrograde cholangiopancreatography, and developed low-voltage ECG. Computed tomography revealed air emboli in the brain, the intestinal veins and in the pericardium. Low-voltage ECG most probably was due to pneumopericardium.

An example of apparently normal electrocardiogram originating from incorrect electrocardiographic acquisition in a patient with ST-segment elevation myocardial infarction: Aslanger et al A valuable lesson and a clarification but still a puzzle. Author’s reply - Corrected Proof

Derek John Rowlands — 2010-07-23

I was delighted to read the carefully considered reply from Aslanger et al to my earlier letter commenting on their article “An example of apparently normal electrocardiogram originating from incorrect electrocardiographic acquisition in a patient with ST-segment elevation myocardial infarction.”

The signal-averaged electrocardiogram before and after electrical cardioversion of persistent atrial fibrillation—implications of the sudden change in rhythm - Corrected Proof

Christer Gottfridsson, Thomas Karlsson, Nils Edvardsson — 2010-07-22

Abstract: Background: Atrial fibrillation (AF), electrical cardioversion (direct current, or DC) shock energy, and a sudden change to sinus rhythm (SR) might all influence the interpretation of the signal-averaged electrocardiogram (SAECG) as risk markers of ventricular tachyarrhythmia.Methods: The SAECG was recorded in 82 patients with persistent AF before and 2 hours after DC and analyzed for ventricular late potentials (LPs) and spectral turbulence.Results: Sixty-nine patients (84%) obtained SR. Their mean (SD) heart rate decreased by 22 (20) beats/min, and the QTcF interval was significantly prolonged, 17 (38) milliseconds, as was the filtered QRS duration, 1.1 (4.7) milliseconds (40 Hz). The proportion of LP positivity (20%) did not change with the change in rhythm. Eight of 60 spectral turbulence–negative patients before DC became positive after DC (P = .01). The change in SAECG variables did not correlate significantly with the amount of energy delivered at DC.Conclusion: The LP analysis provided similar results in AF and SR, whereas the spectral turbulence analysis was more abnormal in SR. The electrical shock itself did not seem to explain this phenomenon.

Proarrhythmia in the setting of acute ST-segment elevation - Corrected Proof

2010-07-20

An 84-year-old woman with persistent atrial fibrillation was admitted to the emergency department complaining of repeated attacks of resting angina, palpitations, and dizziness. She was on oral anticoagulation, amiodarone, and bisoprolol. Transthoracic echocardiography revealed normal left ventricular ejection fraction and dilated left atrium. Ambulatory Holter monitoring revealed several episodes of short-coupled premature ventricular complexes and short runs of polymorphic ventricular tachycardia, initiated by an “R-on-T” phenomenon without QT interval prolongation or short-long-short sequences. All episodes were exclusively associated with ST-segment elevation (). Serum electrolytes and biochemical markers for myocardial damage were normal in 2 consecutive blood samples. Coronary angiography showed diffuse coronary artery ectasia without significant stenosis. She was discharged taking oral verapamil instead of β-blocker. The patient is asymptomatic and free of ischemic and arrhythmic events at 24-hour ambulatory Holter recordings after a 6-month follow-up period.

Analyzing murine electrocardiogram with PhysioToolkit - Corrected Proof

Thomas Galetin, Marco Weiergräber, Jürgen Hescheler, Toni Schneider — 2010-07-20

Abstract: Quantitative electrocardiogram (ECG) analysis is a very important tool in cardiovascular and neuroedocrine research. It is useful in clinical trials with human beings, as well as in animals such as rabbits, rats, and mice, for example, in studying knockout models.The species of interest differ in their typical baseline heart rate and therefore in the sampling rate in ECG detection. However, for obvious reasons, there are no available analysis programs adjusted to each species. We demonstrate how to use PhysioToolkit, an open source software developed by Massachusetts Institute of Technology for physiologic signal processing and analysis in humans, with murine ECG signals, with full control over analysis options. The procedure can be transferred on any other species in an analogue way.

Bivariate phase-rectified signal averaging for assessment of spontaneous baroreflex sensitivity: pilot study of the technology - Corrected Proof

2010-07-20

Abstract: Background: Assessment of spontaneous baroreflex sensitivity (BRS), an index of autonomic function, poses practical challenges. In this pilot study, we propose a novel technique for assessment of spontaneous BRS based on bivariate phase-rectified signal averaging (PRSA). This is an extension of the monovariate PRSA technology used for calculation of deceleration capacity.Methods: A prospective, observational study was conducted in a training cohort of 146 patients with heart failure (New York Heart Association class 2.7 ± 0.8, left ventricular ejection fraction 23.6% ± 9.0%) presenting with sinus rhythm. In all patients, 10-minute recordings of ECG and arterial and blood pressure were obtained in the supine resting position. The algorithm for BRS assessment based on bivariate PRSA (BRSPRSA) included (1) identification of heartbeat intervals occurring at the time of systolic pressure increases, (2) selection of heartbeat adjacent interval sections, (3) alignment and (4) averaging of these segments, and (5) quantification of the average heart beat interval change by Haar wavelet analysis. Primary end point was death of any cause. During mean follow-up of 2.7 ± 1.1 years, 42 patients (28.8%) died.Results: BRSPRSA was significantly associated with the primary end point (3.7 ± 5.3 ms vs −0.33 ± 6.6 ms in survivors and nonsurvivors, respectively). BRSPRSA yielded an area under the receiver operating characteristics curve of 69.8% (95% confidence interval, 59.9-79.7), which was comparable to the area under the curve of left ventricular ejection fraction (70.4%; 95% confidence interval, 61.3-79.5). Using the optimum dichotomy for BRSPRSA of 1.14 milliseconds, 52 (36%) patients had an abnormal BRSPRSA. The 3-year mortality risk of these patients was 45.3% compared to 19.0% in patients with normal BRSPRSA. On multivariate analysis, abnormal BRSPRSA was an independent risk factor from left ventricular ejection fraction ≤ 30% and New York Heart Association class > II.Conclusion: BRSPRSA is an independent and strong predictor of mortality in patients with heart failure. Prospective validation and comparisons with standard measures of BRS are needed.

Models of stretch-activated ventricular arrhythmias - Corrected Proof

Natalia A. Trayanova, Jason Constantino, Viatcheslav Gurev — 2010-07-20

Abstract: One of the most important components of mechanoelectric coupling is stretch-activated channels, sarcolemmal channels that open upon mechanical stimuli. Uncovering the mechanisms by which stretch-activated channels contribute to ventricular arrhythmogenesis under a variety of pathologic conditions is hampered by the lack of experimental methodologies that can record the 3-dimensional electromechanical activity simultaneously at high spatiotemporal resolution. Computer modeling provides such an opportunity. The goal of this review is to illustrate the utility of sophisticated, physiologically realistic, whole heart computer simulations in determining the role of mechanoelectric coupling in ventricular arrhythmogenesis. We first present the various ways by which stretch-activated channels have been modeled and demonstrate how these channels affect cardiac electrophysiologic properties. Next, we use an electrophysiologic model of the rabbit ventricles to understand how so-called commotio cordis, the mechanical impact to the precordial region of the heart, can initiate ventricular tachycardia via the recruitment of stretch-activated channels. Using the same model, we also provide mechanistic insight into the termination of arrhythmias by precordial thump under normal and globally ischemic conditions. Lastly, we use a novel anatomically realistic dynamic 3-dimensional coupled electromechanical model of the rabbit ventricles to gain insight into the role of electromechanical dysfunction in arrhythmogenesis during acute regional ischemia.

In vivo studies of Scn5a+/− mice modeling Brugada syndrome demonstrate both conduction and repolarization abnormalities - Corrected Proof

Claire A. Martin, Yanmin Zhang, Andrew A. Grace, Christopher L.-H. Huang — 2010-07-20

Abstract: Objectives: We investigate the extent to which the electrocardiographic (ECG) properties of intact Scn5a+/− mice reproduce the corresponding clinical Brugada syndrome phenotype and use this model to investigate the role of conduction and repolarization abnormalities in the arrhythmogenic mechanism.Methods and Results: The ECGs were obtained from anesthetized wild-type and Scn5a+/− mice, before and after administration of the known pro- and antiarrhythmic agents flecainide and quinidine. The ECG intervals were measured and their dispersions calculated. Scn5a+/− hearts showed ventricular arrhythmias, ST elevation, and conduction disorders including increased QT dispersion, accentuated by flecainide. Quinidine did not cause ventricular arrhythmias but exerted variable effects on ST segments and worsened conduction abnormalities.Conclusions: The ECG features in an Scn5a+/− mouse establish it as a suitable model for Brugada syndrome and demonstrate abnormal conduction and repolarization phenomena. Altered QT dispersion, taken to indicate increased transmural repolarization gradients, may be useful in clinical risk stratification.

The absence of the ST-segment elevation in acute coronary artery thrombosis: what does not fit, the patient or the explanation? - Corrected Proof

2010-06-30

Abstract: In a few patients with acute proximal thrombotic occlusion of the left anterior descending coronary artery (LAD), tall ischemic T waves never evolve into ST-segment elevation. This was recently inaccurately reported as a “novel sign” of proximal LAD occlusion. It has been speculated that the absence of ST-segment elevation could be attributed to the large area of transmural ischemia, the anatomic variant of Purkinje fibers, or to lack of activation of sarcolemal adenosine triphosphate–potassium channels. This electrocardiographic picture was recently explained by changes in the subendocardial but not in the epicardial action potential, suggesting subendocardial ischemia as the underlying mechanism. We present a patient with thrombotic lesion of proximal LAD, static precordial ST-segment depression, and tall T waves who underwent primary percutaneous intervention and stent placement. Surprisingly, total thrombotic stent occlusion on the following day was associated with ST-segment elevation in precordial leads, indeed supporting the concept of the regional subendocardial ischemia that was first described more than a decade ago.

The frequency of electrocardiographic errors due to electrode cable switches: a before and after study - Corrected Proof

Thomas Thaler, Volker Tempelmann, Marco Maggiorini, Alain Rudiger — 2010-06-30

Abstract: Introduction: Electrocardiographic (ECG) errors due to electrode cable reversal confuse physicians and provoke unnecessary diagnostic tests. They occur in approximately 4% of ECGs performed in the intensive care unit (ICU). We aimed to investigate whether this frequency could be reduced by an appropriate intervention.Methods: All ECGs from consecutive patients were collected at ICU discharge and analyzed by the investigators. Before collecting a second set of ECGs, we educated our ICU staff and performed technical improvements on the electrocardiographs (system approach). Electrocardiographic errors were identified applying previously published morphologic criteria.Results: We collected and analyzed 1123 ECGs from 416 patients. Nine hundred ten ECGs (81%) were recorded in the ICU; and the frequencies of electrode cable misplacements before and after the intervention were 4.8% and 1.2%, respectively (P = .002).Conclusions: Using a system approach, we were able to significantly reduce the frequency of ECG errors due to electrode cable switches by 75%.

Bipolar leads obtained from the unipolar precordial leads for noise filtering - Corrected Proof

Velislav N. Batchvarov, Elijah R. Behr — 2010-06-14

demonstrates a 12-lead electrocardiogram (ECG) excerpt (25 mm/s, 0.5 cm/mV) from a 12-lead 24-hour ambulatory Holter recording (CardioDay, GE Medical Products, Milwaukee, WI, USA, 1000 Hz, 5-μV resolution). All leads except lead I are very noisy, and some segments of the ECG are practically unreadable. Apparently, the noise originates from the left leg cable or electrode. Because the noise is transmitted via the central terminal to all precordial leads, it can be canceled if a bipolar ECG lead is acquired between any 2 precordial electrodes. In , leads V1, V2, V5, and V6 of the same ECG are displayed, along with bipolar precordial leads between V1 (positive pole) and V6 (negative pole) and between V5 (positive pole) and V2 (negative pole)—leads V16 and V52, respectively. These bipolar leads were derived by subtracting the unipolar leads V6 and V2 from V1 and V5, respectively, using a custom-made program. Leads V16 and V52 were chosen because (a) they display a “right ventricular” (ie, mainly negative) and a “left ventricular” (ie, mainly positive) QRS complex, respectively, and (b) they have a large QRS amplitude because their electrodes are relatively far apart.

Usefulness of electrocardiographic parameters as compared with computed tomography measures of left atrial volume enlargement: from the ROMICAT trial - Corrected Proof

2010-05-31

Abstract: Introduction: The 12-lead surface electrocardiogram (ECG) is commonly used as a noninvasive modality to assess for left atrial enlargement (LAE), but data comparing ECG against cardiac computed tomography (CT) for LAE is lacking. We aimed to determine the diagnostic performance of 6 ECG criteria for LAE as compared with CT left atrial volume (LAV) and index to body surface area (LAVI) as the reference standard.Materials and Methods: In 339 patients (age: mean ± mean, 53 ± 12 years; 63% male), we evaluated the quantitative ECG parameters of P duration, P to PR segment ratio, P wave area, and P terminal force in lead V1. We also assessed qualitatively the morphology of bifid and biphasic P waves. Patients were stratified into top and lowest quartile of LAV and LAVI by CT.Results: Of the 6 ECG criteria, patients with P duration greater than 110 milliseconds had a 2½-fold increase likelihood of being in the top quartile of LAV (adjusted odds ratio [OR], 2.51; P = .01) and LAVI (adjusted OR, 2.74; P = .007) as measured by CT. For this ECG criterion, the sensitivity and specificity were 71% and 55% for CT LAE by LAV and 61% and 55% for LAVI. The remaining ECG parameters of LAE assessed (P to PR segment ratio, P terminal force in lead V1, P wave area, bifid, and biphasic P wave) were not associated with LAE by CT-based LAV or LAVI (all P ≥ .20).Discussion: Only P duration greater than 110 milliseconds was independently associated with LAE based on CT-derived LA volume and index. However, none of the established ECG parameters of LAE have sufficient diagnostic accuracies for predicting volumetric enlargement by CT, thus limiting its clinical utility.

An unusual electrocardiogram artifact in a patient with near syncope - Corrected Proof

Emre Aslanger — 2010-05-31

Abstract: Electrocardiogram (ECG) artifacts are common and should be known by every physician. Although usual ECG artifacts can be identified by their clinical context, morphology, and dissociation with underlying normal cardiac rhythm, one may encounter with examples that closely imitate serious disorders. Here, we report an unusual ECG artifact mimicking several serious disorders, which is very exceptional because of its clinical importance, morphology, and association with normal rhythm.

Maybe a dazzle but not puzzle - Corrected Proof

Emre Aslanger — 2010-05-26

We would like to thank the author (Dr Rowlands) for his interest in our article. Also, we would like to add that we believe that his detailed mathematical explanations about limb lead misplacements will make our report more interesting.

“An example of apparently normal electrocardiogram originating from incorrect electrocardiographic acquisition in a patient with ST-segment elevation myocardial infarction”: Aslanger et al: A valuable lesson and a clarification but still a puzzle - Corrected Proof

Derek John Rowlands — 2010-05-24

I read with interest the article by Aslanger et al entitled “An example of apparently normal electrocardiogram originating from incorrect electrocardiographic acquisition in a patient with ST-segment elevation myocardial infarction.” The report provides a valuable reminder of the need to be able to recognize any limb lead connection error. Such errors are, of course, very common. In the case described, appropriate treatment would not have been given had another record not been taken within a short time interval. The authors have done a valuable service in reporting this case, but there are one or two items in the discussion that might benefit from clarification.

Characterization of recombinant hERG K+ channel inhibition by the active metabolite of amiodarone desethyl-amiodarone - Corrected Proof

2010-05-21

Abstract: The aim of this study was to determine the effects of desethyl-amiodarone (DEA), the major metabolite of the class III antiarrhythmic drug amiodarone, on human ether-à-go-go-related gene (hERG) encoded potassium channel current.Materials and methods: Whole-cell patch clamp recordings were made at 37°C of ionic current (IhERG) carried by recombinant hERG channels expressed in HEK-293 cells.Results: Desethyl-amiodarone inhibited IhERG with a half-maximal inhibitory concentration of approximately 158 nmol/L, compared with approximately 47 nmol/L for amiodarone. The inhibitory action of DEA on IhERG was contingent on channel gating, showing significant time and voltage dependence. Desethyl-amiodarone also produced an approximately −9 mV shift in the voltage dependence of activation of IhERG; however, there was no significant preference for activated over inactivated channels.Conclusions: Because hERG underlies native cardiac “IKr” channels, hERG/IKr inhibition by DEA as well as amiodarone may contribute to the overall effects of amiodarone administration on cardiac repolarization.

High-frequency electrocardiogram as a supplement to standard 12-lead ischemia monitoring during reperfusion therapy of acute inferior myocardial infarction - Corrected Proof

2010-05-20

Abstract: Background: Resolution of ST-segment elevation in the electrocardiogram (ECG) is used as a reperfusion sign during thrombolytic therapy in acute myocardial infarction. Analysis of high-frequency QRS components (HF-QRS) might provide additional information. The study compares changes in HF-QRS (150-250 Hz) to ST-segment changes in the standard ECG during thrombolytic therapy.Methods: Twelve patients receiving intravenous thrombolytic therapy were included. A continuous 12-lead ECG recording was acquired for 4 hours.Results: After 1 hour of therapy, 3 patients showed ST-elevation resolution as well as an increase in HF-QRS. These changes in ST and HF-QRS occurred simultaneously. No other patient showed significant changes in ST or HF-QRS after 1 hour. After 2 and 4 hours, there was less concordance between the standard and high-frequency ECGs.Conclusions: In patients with early ST-elevation resolution, the standard and high-frequency ECGs show similar results. Later changes are more disparate and may provide different clinical information.

Ventricular fibrillation induced by radiofrequency ablation for slow ventricular tachycardia associated with left ventricular dysfunction - Corrected Proof

2010-05-10

Abstract: A 59-year-old man with premature ventricular contractions (PVCs) and slow ventricular tachycardia (VT) underwent electrophysiologic testing. The left ventricular ejection fraction was 27%. Activation mapping showed the site of earliest activation to be the posterolateral site of the right ventricle inflow tract, and we considered this to be the focal mechanism underlying the PVCs/slow VT. Radiofrequency current delivered at this site induced a cluster of rapid ventricular beats (sustained VT) with the same QRS morphology as the PVCs, followed by ventricular fibrillation. The PVC/VT focus might have served as an abnormal automatic trigger and driver for the ventricular fibrillation.

Wolff-Parkinson-White alternans caused by adenosine stress test: supernormal conduction as an alternative mechanism - Corrected Proof

Shinji Kinoshita, Takakazu Katoh — 2010-05-05

We have read with much interest a recent report by Khouzam on Wolff-Parkinson-White (WPW) alternans diagnosis unveiled by adenosine stress test. Khouzam presented a 12-lead electrocardiogram in a 41-year-old woman with atypical chest pain. During an adenosine nuclear stress test, intermittent preexcited beats in a bigeminal pattern occurred transiently to confirm the diagnosis of midseptal WPW syndrome (). Khouzam explained that adenosine inducing an atrioventricular nodal blocking effect helped in unmasking the anomalous pathway causing WPW syndrome.

New precordial bipolar electrocardiographic leads for detecting left ventricular hypertrophy - Corrected Proof

Merja Puurtinen, Juho Väisänen, Jari Viik, Jari Hyttinen — 2010-05-03

Abstract: Background: Novel small and wearable electrocardiogram (ECG) devices offer new means of recording cardiac activity in different applications. Our objective was to evaluate the performance of closely separated (6 cm) bipolar leads in differentiating subjects with left ventricular hypertrophy (LVH) from healthy subjects.Methods: The material contained body surface ECG of 236 healthy and 116 LVH subjects. A total of 36 vertical, 30 horizontal, and 66 diagonal bipolar leads located on the anterior thorax were analyzed. The QRS amplitudes were calculated, and the leads' overall diagnostic performance was assessed by receiver operating characteristic (ROC) analysis.Results: The best overall diagnostic performances were obtained from 2 areas: one near the precordial electrodes of standard leads V1 to V3 and the other on lower anterior thorax. Vertical and diagonal bipolar leads located at lower anterior thorax provided the highest ROC areas (≥0.79). These bipolar leads also provided similar sensitivities than the traditional Sokolow-Lyon method.Conclusion: The new short distance vertical and diagonal bipolar leads are efficient in discriminating subjects with LVH from healthy subjects based on QRS amplitude.

The pattern of crescendo TWA may disclose the underlying cardiac pathology - Corrected Proof

2010-04-23

Abstract: We present an exercise test case in which crescendo TWA preceded ventricular tachycardia (VT). The patient was examined due to suspicion of ischemic heart disease. The ST-segment became elevated simultaneously with a distinct alternation in the ST-segment and the first half of the T-wave, and the patient developed polymorphic VT. Coronary angiography disclosed marked stenoses. Earlier reports of TWA in patients with congenital long QT syndrome show a pattern in which the T wave frequently alternates above and below the isoelectric line without concomitant ST-segment changes. In Brugada syndrome patients, the signature ST-T wave pattern is the locus of alternation. Future investigation should elucidate whether specific TWA morphologies may expose underlying heart disease.

Presence of a critical stenosis in left anterior descending coronary artery alongside a short “P-R” and “Q-T” pattern, in the same electrocardiographic record - Corrected Proof

Francisco R. Breijo-Márquez, Manuel Pardo Ríos, Miguel Alcaraz Baños — 2010-04-15

The knowledge of the heart and its functions is increasing every day. However, many cardiac dysfunctions remain undocumented. One of them might be the presence of the Wellens' sign, minimally elevated or isoelectric ST segments, and inverted T waves in the precordial leads, without changes in the QRS complex, together with a shortened of “P-R and Q-T intervals” in the same electrocardiographic record. Both patterns are greatly underdiagnosed. The risk implied by the aforementioned underdiagnosis could have lethal consequences because the inherent problems in a short “P-R”-“Q-T” pattern could be added to those inherent in Wellens' sign.

Are wide complex tachycardia algorithms applicable in children and patients with congenital heart disease? - Corrected Proof

2010-04-12

Abstract: Introduction: Several algorithms have been developed to help determine the etiology of wide complex tachycardias (WCTs) in adults. Sensitivity and specificity for differentiating supraventricular tachycardia (SVT) with aberration from ventricular tachycardia (VT) in adults have been demonstrated to be as high as 98% and 97%. These algorithms have not been tested in the pediatric population. We hypothesize that these algorithms have lower diagnostic accuracy in children and patients with congenital heart disease.Methods: A retrospective review of the pediatric electrophysiology database at Stanford from 2001 to 2008 was performed. All children with WCT, a 12-lead electrocardiogram (ECG) available for review, and an electrophysiology study confirming the etiology of the rhythm were included. Patients with a paced rhythm were excluded. The ECGs were analyzed by 2 electrophysiologists blinded to the diagnosis according to the algorithms described in Brugada et al, and Vereckei et al. Additional ECG findings were recorded by each electrophysiologist.Results: A total of 65 WCT ECGs in 58 patients were identified. Supraventricular tachycardia was noted in 62% (40/65) and VT in 38% (25/65) of the ECGs. The mean age was 13.5 years (SD ± 5.1), the mean weight was 51.8 kg (SD ± 22.4), and 48% (31/65) were male. The mean tachycardia cycle length was 340 milliseconds (SD ± 95). Congenital heart disease (CHD) was present in 37% (24/65) of patients (7 tetralogy of Fallot, 6 Ebstein's, 4 double-outlet right ventricle, 3 complex CHD, 2 d-transposition of great arteries, 1 status-post orthotopic heart transplantation, 1 ventricular septal defect). The Brugada algorithm correctly predicted the diagnosis 69% (45/65) of the time, the Vereckei algorithm correctly predicted the diagnosis 66% (43/65) of the time, and the blinded reviewer correctly predicted the diagnosis 78% (51/65) of the time. There was no difference in the efficacy of the algorithms in patients with CHD vs those with structurally normal hearts. The findings of left superior axis deviation (P < .01) and a notch in the QRS downstroke of V1 or V2 (P < .01) were more common in VT than SVT, whereas a positive QRS deflection in V1 (P = .03) was more commonly present in SVT than VT.Conclusion: The Brugada and Vereckei algorithms have lower diagnostic accuracy in the pediatric population and in patients with congenital heart disease than in the adult population. Left superior axis deviation and a notch in the QRS downstroke were more commonly associated with VT, whereas a positive QRS deflection in V1 was more commonly associated with SVT in this population.

High risk of sudden death associated with a PRKAG2-related familial Wolff-Parkinson-White syndrome - Corrected Proof

Li-Ping Zhang, Bin Hui, Bing-Ren Gao — 2010-04-12

Abstract: Familial appearance of Wolff-Parkinson-White (WPW) syndrome is rare and displays an autosomal dominant inheritance. Here we report a Chinese kindred of WPW syndrome whose unique clinical features consist of a high risk of sudden cardiac death due to atrial fibrillation, causing a rapid antegrade conduct over the accessory pathway. The mutation in the PRKAG2 gene was identified as responsible for the familial form of WPW syndrome.

T-wave alternans and risk of sudden cardiac death in community-dwelling elderly subjects - Corrected Proof

John E. Madias — 2010-04-09

The data of the article by Stein et al published on line in January 22, 2010, in the Journal are somewhat unique in that there was a large number of subjects with a repeat Holter examination. Notwithstanding a progression of clinical or subclinical underlying heart disease or other disease, or improvement as a result of therapies administered or lifestyle changes instituted, it would be of interest to evaluate in the subjects with 2 Holter examinations, 5 years apart, the rates of conversion of a positive to a negative and vice versa T-wave alternans (TWA) test result, and what were the values of TWA in microvolt in the 2 examinations of the patients with 2 tests who had sudden cardiac death (N) and the control subjects (2N) who did not. This inquiry is made in the vein expressed by some that the reproducibility of the TWA testing (both short-term and long-term) in patients with stable disease, clinical worsening, or improvement may be of value in the monitoring of patients. The authors reported the average of the 3 highest TWA values, which they termed the peak TWA for each of the 2 Holter leads for each patient. T waves vary widely in repeat Holter tests in the same patient, and thus, one wonders how influential were such changes in the T waves in determining the magnitude of the TWA. To this end, it will be of value to evaluate the relationship of the TWA magnitude to the corresponding T-wave amplitude in each of the 2 Holter leads of each studied patient. Also, along the same line of reasoning, it would be contributory to ascertain whether the TWA magnitude change from the repeat Holter tapes in each subject of sudden cardiac death or control subgroups could be accounted for by the change in the corresponding amplitude of the T waves in the same Holter lead. This could be evaluated by assessing TWA values by the amplitude of the corresponding T waves, if a modified moving average analysis used the peak of T wave, or the area under the curve of the ST-segment onset to T-wave offset, or any other time window in between, used in calculating TWA. I would greatly appreciate a response by the authors on the above.

Failure in short-term prediction of ventricular tachycardia and ventricular fibrillation from continuous electrocardiogram in intensive care unit patients - Corrected Proof

2010-04-08

Abstract: Background: Patients in the intensive care unit (ICU) setting are prone to malignant ventricular arrhythmias. We sought to test whether electrocardiographic (ECG) markers of autonomic tone, ventricular irritability, and repolarization lability could be used in short-term prediction of ventricular arrhythmias in this patient population.Methods: We studied 38 patients with sustained (>30 seconds) monomorphic ventricular tachycardia, polymorphic ventricular tachycardia, or ventricular fibrillation while monitored in the ICU and 30 patients without arrhythmia in the ICU who served as controls. All patients had at least 12 hours of continuously recorded multilead ECG before arrhythmic event. Mean heart rate and measures of heart rate variability, QT variability, and ventricular ectopy were quantified in 1-hour epochs for the 12 hours before the arrhythmic event and in 5-minute epochs for the last hour preevent (and using a random termination time point in controls).Results: A modest downward trend in QT variability and a rise in heart rate were observed hours before polymorphic ventricular tachycardia and ventricular fibrillation events, although no significant changes heralded monomorphic ventricular tachycardia and no changes in any parameter predicted imminent ventricular arrhythmia of any type. There were no significant differences in ECG parameters between arrhythmia patients and controls.Conclusions: In ICU patients, sustained ventricular arrhythmias are not preceded by change in ECG measures of autonomic tone, repolarization variability, and ventricular ectopy. Short-term arrhythmia prediction may be difficult or impossible in this patient population based on ECG measures alone.

Heterogeneous memory in restitution of action potential duration in pig ventricles - Corrected Proof

Linyuan Jing, Sonam Chourasia, Abhijit Patwardhan — 2010-04-08

Abstract: Background: Restitution of action potential duration and memory importantly affect electrical stability in ventricles. Studies have reported heterogeneous restitution among different regions of the ventricles. However, existence of heterogeneity in memory is not as well investigated.Methods: Transmembrane potentials were recorded in endocardial and epicardial tissues from both ventricles of farm pigs. Pacing protocols with sinusoidally changing diastolic intervals were used to reveal hysteresis in restitution, from which quantitative measures of memory were calculated.Results: Larger measures of hysteresis were observed in the endocardium than the epicardium (P < .05): loop thickness (in milliseconds), 26.9 vs 16.2; overall tilt, 0.376 vs 0.249; and loop area (in square milliseconds), 7288 vs 4146. Except for overall tilt, no significant differences in these measures were observed between ventricles.Conclusion: Heterogeneity in memory exists in pig ventricles. Because regions with the steepest restitution may also have the largest memory, our results suggest that heterogeneity in memory should also be factored in when predicting electrical stability.

Prevalence of electrocardiographic abnormalities in a middle-aged, biracial population: Coronary Artery Risk Development in Young Adults study - Corrected Proof

2010-04-07

Abstract: Background: Few studies to date have described the prevalence of electrocardiographic (ECG) abnormalities in a biracial middle-aged cohort.Methods and Results: Participants underwent measurement of traditional risk factors and 12-lead ECGs coded using both Minnesota Code and Novacode criteria. Among 2585 participants, of whom 57% were women and 44% were black (mean age 45 years), the prevalence of major and minor abnormalities was significantly higher (all P < .001) among black men and women compared to whites. These differences were primarily due to higher QRS voltage and ST/T-wave abnormalities among blacks. There was also a higher prevalence of Q waves (Minnesota Code 1-1, 1-2, 1-3) than described by previous studies. These racial differences remained after multivariate adjustment for traditional cardiovascular (CV) risk factors.Conclusions: Black men and women have a significantly higher prevalence of ECG abnormalities, independent of traditional cardiovascular risk factors, than whites in a contemporary cohort of middle-aged participants.

Functional atrioventricular conduction block in an elderly patient with acquired long QT syndrome: elucidation of the mechanism of block - Corrected Proof

2010-03-24

Abstract: The long QT syndrome (LQTS) is occasionally complicated by impaired atrioventricular (AV) conduction. This form of LQTS can manifest before birth or during neonatal life, and no previous report has demonstrated LQTS complicated by impaired AV conduction in elderly patient. This case report describes an elderly patient with an acquired form of LQTS who developed ventricular fibrillation that was successfully defibrillated during admission to the hospital. Electrophysiologic study demonstrated that HV interval was 38 milliseconds and QT interval was 635 milliseconds during sinus rhythm cycle length of 1167 milliseconds. 1:1 AV conduction was maintained to a pacing cycle length of 545 milliseconds with an AH interval of 144 milliseconds, HV interval of 44 milliseconds, and right ventricular monophasic action potential duration of 360 milliseconds. However, 2:1 HV block developed at a pacing cycle length of 500 milliseconds. Intravenous administration of mexiletine decreased the cycle length of developing HV block to 360 milliseconds.

How many leads through persistent left superior vein cava and coronary sinus? - Corrected Proof

Giovanni Morani, Corinna Bergamini, Mauro Toniolo, Corrado Vassanelli — 2010-02-15

Abstract: In the modern implanting era with progressive expanding indications to resynchronization therapy, upgrading procedure is a relatively common event. Persistent left superior vena cava (PLSVC), the most common venous abnormality, may exacerbate technical difficulties. We describe the procedure of upgrading from a dual chamber pacemaker to resynchronization/defibrillation system with a total of 4 leads through a PLSVC entering a dilated coronary sinus (CS) never described before. The case report, in addition to the description of a unique technical approach, raises a lot of clinical questions about how many leads we can introduce in such a venous structure and inside CS without hemodynamic impact on venous drainage potentially leading to life-threatening situations.

Artifacts posing as premature ventricular beats in an “event recorder” tracing - Corrected Proof

John E. Madias — 2010-02-01

Atrioventricular block with 4:2 conduction pattern: concealed electrotonic conduction as an alternative mechanism - Corrected Proof

Shinji Kinoshita, Takakazu Katoh — 2010-01-27

We have read with much interest a recent report by Jastrzebski and Kukla on atrioventricular (AV) block with 4:2 conduction pattern. They presented electrocardiograms showing AV block with 4:2 conduction pattern in a patient with myocardial infarction. They proposed 3 alternative explanations: (1) supernormal conduction; (2) 2-level block with 4:1 conduction ratio in the upper level and 3:2 conduction ratio in the lower level; and (3) presence of 2 populations of Purkinje cells in the remaining, critically injured, fascicle: one with the phase-3 block and the other with slow diastolic depolarization leading, during a pause after the first nonconducted P, to phase-4 block.

New York Heart Association Functional class influences the impact of diabetes on cardiac autonomic function - Corrected Proof

Phyllis K. Stein, Prakash Deedwania — 2010-01-25

Abstract: Background: Diabetes (D) and heart failure (HF) are associated with abnormal heart rate variability (HRV). It is unclear whether the HRV effect of having both is cumulative.Methods: Pretreatment HRV (traditional, nonlinear, and heart rate [HR] turbulence) in 80 D versus 74 non-D (ND) systolic HF patients was compared by New York Heart Association II versus III among patients entered into an HF drug evaluation study.Results: Age-adjusted HR was lower in class II D versus class III and most HRV including HR turbulence was better in class II ND versus all others, with few differences between class II D and class III ND and D patients.Conclusion: The effect of D and HF on autonomic function may be cumulative in class II, but D may have little additional effect on most HRV in class III patients. The prognostic value of different HRV measures in D versus ND HF patients should be further investigated.

Repetitive polymorphic ventricular tachycardia initiated by phase 4 block in the His-Purkinje system - Corrected Proof

Jose' Dizon, Daniel Wang, Alan Vainrib — 2010-01-25

Abstract: We report a case of a patient who developed repetitive episodes of polymorphic ventricular tachycardia with a stereotypical pattern of initiation. A premature atrial complex would result in a brief pause followed by left bundle branch block aberrancy. Ventricular bigeminy would ensue followed by episodes of polymorphic ventricular tachycardia, some requiring cardioversion. We postulate that delay within the His-Purkinje system initiated by phase 4 block was proarrhythmic in this patient.

Pleomorphic ventricular tachycardia originating from Purkinje fiber network of left anterior fascicle - Corrected Proof

2010-01-21

Abstract: A 55-year-old woman with recurrent syncope and palpitation experienced polymorphic ventricular tachycardia (VT) and more than 3 monomorphic VTs with a right bundle branch block configuration as inferior, middle, and superior axis. During the pleomorphic VT, the diastolic potential (dp) was recorded at the anterolateral left ventricle. Changes in the QRS morphology were associated with the time between dp and onset of QRS complex (dp-V interval), and prolongation of dp-V interval terminated the VT. In addition, the delayed potentials were seen during sinus rhythm around this area. Delivery of radiofrequency current targeting the delayed potentials abolished all the VTs. Different exits from relatively large area of slow conduction in the left anterior fascicle might have produced the pleomorphic VTs.

Variable presentation of ventricular tachycardia-like electrocardiographic artifacts - Corrected Proof

Jason M. Tarkin, Nearchos Hadjiloizou, Sam Kaddoura, Julian Collinson — 2009-11-25

Abstract: Diagnosis of clinically significant ventricular tachycardia (VT) relies on accurate electrocardiogram (ECG) interpretation, in the context of a convincing clinical picture. ECG artifacts resembling VT are common and can be misleading. We present two instances of VT-like ECG artifacts, which demonstrate the variable presentation of such artifacts and highlight ways in which these ECG tracings can be distinguished from true VT.

WITHDRAWN: “Pseudo-high lateral leads Brugada pattern” due to lead reversal - Corrected Proof

2008-08-26

Available online August 26, 2008This article has been withdrawn consistent with Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). The publisher apologizes for any inconvenience this may cause.