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Discussion The electrocardiogram shows a wide complex irregular tachycardia with a right bundle branch block–like pattern. The QRS morphology is not consistent with typical right bundle branch block because of the monophasic R wave in lead V1, unusual axis, and slurring of the initial forces. A long history of palpitations in a young man suggests the possibility of a manifest or concealed accessory pathway. The wide QRS complex points toward preexcited QRS complexes. Ventricular tachycardia is much less likely in a young man. Does this mean there is preexcited atrial fibrillation? No. A close examination of the QRS complexes reveals inverted P waves in the inferior

Telemetry devices for electrocardiographic (ECG) recording in conscious rats make it possible to obtain long-lasting recordings over extended periods of time, which raises the need for an automatic arrhythmia detection procedure. Numerous algorithms of arrhythmia detection have been developed for analyzing human ECG data. These algorithms, however, are not well suited for recordings characterized by nonsustained arrhythmias and variable QRS morphology, hence the need for a new algorithm. In 5 spontaneously hypertensive rats, 24-h ECG recordings were obtained once a month, from 6 to 11 months of age. A common algorithm detected R peaks, and artifacts were discarded either visually or by using an automatic procedure. All atrial and ventricular tachyarrhythmias were visually assessed. Using RR interval time series, automatic identification of tachyarrhythmias was performed by a fuzzy automaton. Parameters of the automaton were optimized using a cross-validation technique. The thirty 24-h recordings yielded a total of 161,615 atrial arrhythmic beats and 5186 ventricular arrhythmic beats. The automatic procedure provided a high sensitivity (0.89) and positive predictive value (0.91). This new algorithm is appropriate for telemetric recordings of ECG in rats, and allows a fully automatic, computationally efficient procedure for arrhythmia detection with a good performance.

It is recognized that a type of idiopathic ventricular tachycardia (VT) arises from the left ventricular outflow tract (LVOT). This VT exhibits sustained or nonsustained forms, but also appears as frequent premature ventricular contractions (PVCs) of monomorphic QRS morphology. The prognosis is almost uniformly benign. We describe a patient with tachycardiomyopathy resulting from LVOT VT.

International audience; We present an example of sudden modification in QRS morphology during ventricular pacing inside a scar-related isthmus. This is explained by a "concealed" sudden block in both the orthodromic and antidromic wavefront directions, allowing then the activation to proceed through a now overt antidromic conduction.

The 12-lead electrocardiogram (ECG) is the most frequently used technology in clinical cardiology. It is critical for evidence-based management of patients with most cardiovascular conditions, including patients with acute myocardial infarction, suspected chronic cardiac ischaemia, cardiac arrhythmias, heart failure and implantable cardiac devices. In contrast to many other techniques in cardiology, the ECG is simple, small, mobile, universally available and cheap, and therefore particularly attractive. Standard ECG interpretation mainly relies on direct visual assessment. The progress in biomedical computing and signal processing, and the available computational power offer fascinating new options for ECG analysis relevant to all fields of cardiology. Several digital ECG markers and advanced ECG technologies have shown promise in preliminary studies. This article reviews promising novel surface ECG technologies in three different fields. (1) For the detection of myocardial ischaemia and infarction, QRS morphology feature analysis, the analysis of high frequency QRS components (HF-QRS) and methods using vectorcardiography as well as ECG imaging are discussed. (2) For the identification and management of patients with cardiac arrhythmias, methods of advanced P-wave analysis are discussed and the concept of ECG imaging for noninvasive localisation of cardiac arrhythmias is presented. (3) For risk stratification of sudden cardiac death and the selection of patients for medical device therapy, several novel markers including an automated QRS-score for scar quantification, the QRS-T angle or the T-wave peak-to-end-interval are discussed. Despite the existing preliminary data, none of the advanced ECG markers and technologies has yet accomplished the transition into clinical practice. Further refinement of these technologies and broader validation in large unselected patient cohorts are the critical next step needed to facilitate translation of advanced ECG technologies into clinical cardiology.

Patient monitoring algorithms which use multimodal physiological waveforms are needed to reduce alarm fatigue by alarming only for physiologic events and not signal artifacts. When combining information from multiple ECG signals, computational approaches that automatically identify artifacts in ECG signals play an important role. Signal quality indices (SQIs) have been derived which can differentiate between ECG signal artifacts and normal QRS morphology. Some of these SQIs are derived using beat detections and might be affected by the beat detector used. Using ECG signals from the PhysioNet/Computing in Cardiology Challenge 2015 training set, we studied the effect of beat detector on previously reported ECG SQIs derived using beat detections. We found that, while being affected by the beat detector, some of these SQIs can predict beat detector failure. Using beat detector specific SQIs can improve the designs of robust monitoring algorithms.

Introduction Cardiac resynchronisation therapy (CRT) was initially developed to treat patients with left bundle branch block (LBBB). However, many patients with heart failure have a widened QRS but neither left-BBB nor right-BBB; this is called non-specific intraventricular conduction delay (NICD). It is unclear whether CRT is effective in this subgroup of patients. Methods and analysis The NICD-CRT study is a prospective, double-blind, randomised (1:1), parallel-arm, multicentre trial comparing the effects of CRT in patients with heart failure, a reduced left ventricular ejection fraction (LVEF

Since 1998, the Theo Rossi di Montelera (TRM) forum has brought together researchers working on computer modelling, experimental research, and clinical research, with the objective to facilitate the translation of research findings in computer modelling of the heart into the clinical field. The 8th TRM forum was held at Lugano, Switzerland, on 6–8 December 2015, organized by the TRM foundation and hosted by the Center for Computational Medicine in Cardiology in Lugano. The theme was ‘Towards Integration of Cardiac Functions’. In this forum, cardiac function was addressed from the perspectives of electrical cardiac function, mechanical cardiac function, and circulatory function. Electrical cardiac function is generally assessed clinically with a body-surface electrocardiogram (ECG). However, the ECG represents an integrative measure of whole heart electrical activity, from which it is sometimes challenging to derive information about local cardiac activity. Computer models can help us to derive better patient-specific knowledge from routine ECG and determine the underlying electrical activation sequence. An example was presented by Cardone-Noott et al. 1 with a multi-scale computational study on the role of ventricular endocardial activation sequences on QRS complex variations in both healthy hearts and in the presence of intraventricular block. This study provides physiological insights on ECG biomarkers in terms of QRS morphology and location of early endocardial activation sites. Van Dam et al. 2 presented a novel method to localize premature ventricular contractions on the papillary muscles using a 12-lead ECG together with cardiac anatomy and torso geometry derived from magnetic resonance imaging (MRI). The precise localization of the site of origin of premature ventricular contractions could facilitate the planning and execution of an ablation procedure. Saha et al. 3 developed a computer model of the atria and torso to study the changes in P wave morphology resulting from pulmonary vein (PV) ablation. Results were …

Background: There is a paucity of data concerning the use of QRS morphology patterns for identifying pacing sites during left ventricle (LV)-only epicardial pacing in patients with a biventricular device. The objective of this study was to identify QRS patterns during LV-only pacing, and to establish their relationship with LV lead position. In addition, to validate the diagnostic performance of such electrocardiogram (ECG) patterns for predicting posterolateral versus anterior and apical versus nonapical LV pacing site. Methods: The study retrospectively analyzed data from 376 cardiac resynchronization therapy device patients. Data analyzed included ECGs registered during LV-only VVI pacing, fluoroscopic projections, and lateral chest roentgenograms that documented postimplantation LV lead position. Phase one of the study involved categorization of the ECG patterns of the first 66 study cases. Phase two of the study examined the association between ECG pattern and different LV lead positions. Results: As the LV epicardial pacing site became more anteroapical, the LV-only paced QRS complexes in the precordial leads became more negative. Three ECG patterns were identified (posterolateral, intermediate, and anteroapical), and their distribution was found to be associated with LV lead position (P < 0.001). The posterolateral ECG pattern was mostly observed in cases where the LV lead was in the posterolateral area (diagnostic accuracy of 89.1% for predicting a nonapical LV lead position). The anteroapical ECG pattern was associated with LV leads in anteroapical segments (specificity of 98.5%, accuracy of 89.1% for predicting an anteroapical pacing site). Conclusions: Posterolateral and anteroapical ECG patterns are highly predictive of LV lead position. (PACE 2012; 35:1361–1368)

Red blood cell distribution width (RDW) predicts adverse outcomes in patients with heart failure. We aimed to investigate the prognostic value of RDW on response to cardiac resynchronization therapy (CRT).Sixty-six consecutive patients (mean age, 57 ± 13 years; 42 men) undergoing CRT were included in the study. Hematological parameters and echocardiographic parameters were measured before and 6 months after CRT. An echocardiographic response to CRT was defined as a ≥15 % relative increase in left ventricular ejection fraction after 6 months.After 6 months of CRT, 47 (71 %) patients were responders. High baseline RDW levels were found in 11 (23 %) and 10 (52 %) patients in responders and non-responders, respectively (p 0.05). In non-responders, RDW at 6 months was significantly high compared to baseline RDW (17.1 ± 2 vs. 19 ± 2.9) (p 0.001). There was not any significant change in RDW after CRT in responders (16 ± 1.6 vs. 15.5 ± 1.4) (p 0.05). In multivariate analysis, significant associates of response to CRT were evaluated adjusting for QRS width, QRS morphology, age, New York Heart Association functional class, hemoglobulin, and RDW level. Baseline RDW level was the only predictor of response to CRT (odds ratio, 1.435; 95 % confidence interval, 1.059-1.945, p = 0.020).Our data suggest that patients with elevated RDW at baseline are associated with poor response to CRT. Therefore, RDW at baseline could help to identify patients with response to CRT.

P e r s i s t e n t l e f t s u p e r i o r v e n a c a v a r e p r e s e n t s a c o n g e n i t a l v a s c u l a r d e f e c t o f t h e venous system, and is usually discovered accidentally. Temporary pacemaker lead placement should be performed under the fluoroscopy control, but also by using the ECG QRS morphology. Echocardiography also represents a reliable noninvasive diagnostic tool for the assessment of temporary pacemaker lead position. Acta Medica Medianae 2011; 50(3):54-57.

A 74-year-old man with symptomatic complete heart block underwent right ventricular apical permanent pacemaker implantation. The postoperative ECG showed, as expected, completely paced left bundle branch block QRS morphology. However, at the 2-month follow-up examination, his ECG showed paced right bundle branch block (RBBB) QRS morphology, although the patient was asymptomatic. On evaluation, pacemaker functioning was normal with no evidence of lead displacement. This case report highlights that RBBB morphology of paced QRS complex is not always a red flag sign.

A 62-year-old man with severe coronary artery disease and a left ventricular aneurysm underwent catheter ablation of ventricular tachycardia (VT) with right bundle branch block QRS morphology. Endocardial bipolar voltage mapping with standard threshold settings demonstrated no low-voltage areas within the aneurysm. Catheter ablation of the epicardial surface of the aneurysm eliminated the VT. Endocardial bipolar voltage mapping with any other settings could not predict the site of the epicardial arrhythmogenic substrate whereas endocardial unipolar voltage mapping could. Endocardial unipolar voltage mapping may be helpful for predicting epicardial arrhythmogenic substrates. (PACE 2012; 35:e13–e16)

Background: Prolonged right ventricle (RV) apical pacing is associated with left ventricle (LV) dysfunction due to dysynchronous ventricular activation and contraction. Alternative RV pacing sites with a narrower QRS compared to RV pacing might reflect a more physiological and synchronous LV activation. The purpose of this study was to compare the QRS morphology, duration, and suitability of RV outflow tract (RVOT) septal and mid-RV septal pacing. Methods: Seventeen consecutive patients with indication for dual-chamber pacing were enrolled in the study. Two standard 58-cm active fixation leads were passed to the RV and positioned in the RVOT septum and mid-RV septum using a commercially available septal stylet (model 4140, St. Jude Medical, St. Paul, MN, USA). QRS duration, morphology, and pacing parameters were compared at the two sites. The RV lead with less-satisfactory electrical parameters was withdrawn and deployed in the right atrium. Results: Successful positioning of the pacing leads at the RVOT septum and mid-RV septum was achieved in 15 patients (88.2%). There were no significant differences in the mean stimulation threshold, R-wave sensing, and lead impedance between the two sites. The QRS duration in the RVOT septum was 151 ± 14 ms and in the mid-RV septum 145 ± 13 ms (P = 0.150). Conclusions: This prospective observational study shows that septal pacing can be reliably achieved both in the RVOT and mid-RV with active fixation leads using a specifically shaped stylet. There are no preferences in regard to acute lead performance or paced QRS duration with either position. (PACE 2010; 33:1169–1173)

A case of Wolff-Parkinson-White syndrome with supraventricular tachycardia is presented in which 2 atrioventricular (AV) reentry circuits are identified. The first circuit used the AV node in the antegrade limb and a left lateral accessory pathway in the retrograde limb. The second circuit used an atriofascicular accessory pathway as the antegrade limb and the left lateral accessory pathway as the retrograde limb. The characteristics of these tachycardias are described, along with diagnostic maneuvers used in the electrophysiology laboratory. Mapping and ablation of both of these accessory pathways is also described. This article is aimed at clinical electrophysiologists interested in management of complex supraventricular tachycardias in the electrophysiology laboratory.

Ventricular tachycardia (VT) in patients without structural heart disease can be observed in 10% of patients presenting with ventricular arrhythmias. These VTs are characterized by QRS morphology, ventricular origin and their response to pharmacologic agents. It is essential to rule out structural heart disease in this population as this can significantly alter the management and the long-term prognosis. These VTs generally have a benign course and therapeutic options are aimed at relieving symptoms related to the arrhythmia. Medical therapy is effective in many patients and radiofrequency offers a cure to those who are refractory to medical therapy. Careful attention to the electrocardiogram can help localize the origin of the VTs, which is crucial when planning an ablation strategy.

Background: The current recommendation for cardiac resynchronization therapy (CRT) in congestive heart failure (CHF) patients is based on QRS duration, not on QRS morphology. It is not known whether patients with right bundle branch block (RBBB) respond to CRT. Hypothesis: This study was performed to compare the effects of CRT in CHF patients with pure RBBB vs those with a coexisting left hemiblock (LHB). Methods and Patient Population: A total of 271 consecutive patients who underwent CRT at Montefiore Medical Center were analyzed. Baseline ECGs were analyzed by 2 reviewers for RBBB and further classified into those with a coexisting LHB. Response to CRT was defined to be, at ≥6 months after CRT, either an improvement in ejection fraction (EF) of at least 5 %, or an improvement in New York Heart Association (NYHA) CHF class. A total of 44 patients were identified: 1 8 had pure RBBB and 2 6 had a coexisting LHB. The 2 groups were similar in respect to baseline characteristics (P > 0.05). Results: Only 4 out of 1 8 patients with pure RBBB compared to 1 8 out of 2 6 with LHB (P = 0.005) had an improvement in EF ≥5%. The mean EF was ―1% in the pure RBBB group, but +5.4% in those with LHB (P = 0 . 0031 ). Improvement in NYHA class was seen in o out of 1 8 with pure RBBB vs 7 out of 26 patients with LHB (P = 0.03). Conclusion: If patients with RBBB also had LHB, their response to CRT was significantly better than if they had RBBB alone.

Background: In this study we evaluate wide QRS complexes observed during pharmacologic termination of supraventricular tachycardias. Methods: Patients with supraventricular tachycardia, undergoing electrophysiologic study were enrolled. 12 mg of adenosine or 10 mg of verapamil were administered during tachycardia, under continuous monitoring of intaracardiac and surface electrocardiograms. Electrocardiographic features of ventricular ectopy were noted. Results: Seventy-four patients were enrolled. 48 patients were randomized to adenosine and 26 to verapamil. Five different appearance patterns of ventricular ectopy were observed during termination of tachycardias. All wide QRS complexes were of ventricular origin and all of them were observed during the termination of tachycardia. Adenosine more frequently resulted in appearance of ventricular beats (15.4% vs 41.7%, P = 0.003), and this was more frequently observed in patients with atrioventricular nodal reentrant tachycardia. Patients with ventricular beats were younger than those without, in both, verapamil (47.5 ± 15.6 vs 65.0 ± 8.8 years, P = 0.04) and adenosine (40.9 ± 13.8 vs 49.7 ± 16.8, P = 0.03) groups. Left bundle branch block (LBBB)/superior axis morphology was most frequent morphology in adenosine group (55%). Two of 4 patients in verapamil group displayed LBBB/inferior axis QRS morphology and another 2 patients displayed LBBB/superior axis morphology. Conclusions: Noncatheter induced, five different appearance patterns and four distinct morphologies of ventricular origin were observed. Most of them do not directly terminate tachycardia, but are associated with its termination and are not observed in ongoing tachycardia.

Macro-Reentrant ARVC epi-VT with a Focal Endo-Activation. A 55-year-old man with arrhythmogenic right ventricular cardiomyopathy underwent catheter ablation of ventricular tachycardia (VT) with left bundle branch block and left superior axis QRS morphology with an early precordial transition. Endocardial mapping during the VT revealed a focal activation pattern from a small region of low voltage in the left ventricular (LV) septum. Despite earliest endocardial activation in the LV septum, epicardial mapping demonstrated a macro-reentrant circuit with successful catheter ablation at an inferior peritricuspid annular site. Activation from the reentrant circuit propagated through the scar area in the epicardial right ventricle to the remote endocardial LV breakout site.

Fetal monitoring using abdominally recorded signals (ADS) allows physicians to detect occurring changes in the well-being state of the fetus from the beginning of pregnancy. Mainly based on the fetal electrocardiogram (fECG), it provides the long-term fetal heart rate (fHR) and assessment of the fetal QRS morphology. But the fECG component in ADS is obscured by the maternal ECG (mECG), thus removal of the mECG from ADS improves fECG analysis. This study demonstrates the performance of the event-synchronous interference canceller (ESC) in mECG removal from ADS data, recorded during pregnancy and labor. Its advantage as a compensation method for extended ADS processing is discussed.

Echocardiography shows that multiphasic septal movement and a septal to lateral apical systolic left ventricular (LV) motion have a high predictive value for dyssynchrony and the response to cardiac resynchronisation therapy (CRT). Presence of dyssynchrony is also the major marker for CRT response in the presence of scar tissue, provided the interventricular (V-V) pacing interval is optimalised. For atrioventricular (AV) interval optimisation, the velocity-time integral of the transmitral flow has an excellent correlation with invasive LVdP/dtmax. In acute haemodynamic measurements, LVdP/dtmax shows strongly the effect of AV and V-V optimisation. It also illustrates that the haemodynamic effect of LV pacing when associated with intrinsic conduction over the right bundle is equal to or better than biventricular pacing. We found that once AV and V-V interval were optimised, QRS morphology could be used as a template for optimal therapy. Automated continuous optimisation of the pacing intervals will be the big challenge for the future. (Neth Heart J 2008;16(suppl 1):S32-S35).

Symptomatic arrhythmias are frequently observed in the intensive care unit and often lead to significant hemodynamic compromise because of the presence of multisystem disease. In particular, prompt evaluation of patients with tachycardia is critical because treatment depends on the accurate diagnosis of the arrhythmia mechanism. The electrocardiogram remains the most important diagnostic tool for the evaluation of both wide complex and narrow complex tachycardia. For wide complex tachycardia, evaluation of the atrioventricular relationship and QRS morphology are critical, and for narrow QRS complex tachycardias, evaluation focuses on identification of the location and morphology of P waves. Bradycardia can arise from sinus node dysfunction or atrioventricular conduction block.

Idiopathic ventricular tachycardia (VT) is an uncommon form of VT that is seen in patients without structural heart disease. It is commonly seen in young patients and usually has a benign course. Recent studies have delineated the mechanisms and anatomical locations of this form of VT. Recognition of various forms of idiopathic VT based on characteristic QRS morphology from the 12-lead electrocardiogram (ECG) has important prognostic and therapeutic implications. The understanding of the mechanisms of idiopathic VT has led to the use of specific antiarrhythmic drugs targeting particular arrhythmias. Recent technological advances in the field of mapping and catheter ablation have led to a suitable alternative to drug therapy with a very high cure rate. This review describes the clinical features, ECG recognition, and management of idiopathic monomorphic VT.

Electrocardiographic characteristics can be useful in differentiating between right ventricular outflow tract (RVOT) and aortic sinus cusp (ASC) ventricular arrhythmias. Ventricular arrhythmias originating from ASC, however, show preferential conduction to RVOT that may render the algorithms of electrocardiographic characteristics less reliable. Even though there are few reports describing ventricular arrhythmias with ASC origins and endocardial breakout sites of RVOT, progressive dynamic changes in QRS morphology of the ventricular arrhythmias during ablation obtained were rare. This case report describes a patient with symptomatic premature ventricular contractions of left ASC origin presenting an electrocardiogram (ECG) characteristic of right ventricular outflow tract before ablation. Pacing at right ventricular outflow tract reproduced an excellent pace map. When radiofrequency catheter ablation was applied to the right ventricular outflow tract, the QRS morphology of premature ventricular contractions progressively changed from ECG characteristics of right ventricular outflow tract origin to ECG characteristics of left ASC origin. Successful radiofrequency catheter ablation was achieved at the site of the earliest ventricular activation in the left ASC. The distance between the successful ablation site of the left ASC and the site with an excellent pace map of the RVOT was 20 mm. The findings could be strong evidence for a preferential conduction via the myocardial fibers from the ASC origin to the breakout site in the right ventricular outflow tract. This case demonstrates that ventricular arrhythmias with a single origin and exit shift may exhibit QRS morphology changes.

International audience; We studied the effect of exercise-induced ischemia on high-resolution body surface potential maps in the depolarization interval. In particular our aim was to evaluate the effectiveness of selected nine ECG parameters in diagnostics of ischemic heart disease (IHD). The study group consisted of 123 subjects. The distributions of ECG signals averaged in time at rest and at peak exercise were compared. It was observed that for patients with IHD, averaged decreases of QRS amplitude at peak exercise were higher than in the control group and in the group of patients without IHD. IHD was associated also with enlargement of the area on the thorax surface where the decrease in the amplitude and increase in shape changes of the QRS complex were observed. The most effective parameters for the separation of patients with IHD were quantifiers of QRS shape changes. The use of an optimized ECG electrode layout improves the diagnostic value of QRS morphology descriptors.

Patients suffering from heart failure with left bundle branch block (LBBB) can be effectively treated by resynchronization therapy (CRT). The ejection fraction, QRS duration (QRSd) and QRS morphology are the main selection criteria. Unfortunately, approximately one-third of CRT recipients are non-responders. Here we introduce an additional marker capable of distinguishing ventricular dyssynchrony more accurately.

The QRS complex is the most striking waveform within the electrocardiogram (ECG). QRS provides the fundamentals for almost all automated ECG analysis algorithms. We proposed a novel method for classification of ECG beats using shared counters. We first developed a real-time QRS detection technique using two-phase hashing to extract precise QRS points. Then we proposed a classifier for profiling an ECG of normal patient. Our proposed technique depends much on the series of data corresponding to particular feature. For minimize the memory requirement shared counters concept has used. The algorithm automatically adjusts parameters periodically to adapt to ECG changes as QRS morphology and heart rate. The significance of such profiling is for diagnosis of various heart diseases. Automatic abnormal cardiac behavior of any individual can be detected by using this system.

Background: Common electrocardiogram (ECG) manifestations in acute pulmonary em­bolism (APE) include ST-segment deviation (STDV) along with negative T-waves (NTW). STDV could occur in 3 typical ischemic patterns: (i) the left ventricular (LV) subendocardial ischemic pattern; (ii) the right ventricular (RV) transmural ischemic pattern; and (iii) the LV subendocardial plus RV transmural ischemic pattern. The purpose of this study was to evalu­ate the relationship of STDV and adverse clinical outcomes and to identify the relationship of relatively normal ECG and favorable clinical outcomes. Methods: Retrospective analysis of electronic charts in APE patients was performed in a tertiary hospital. ECGs on admission were obtained and classified as with or without STDV. Adverse clinical outcomes were defined as need to intensify therapy and 30-day mortality. Relatively normal ECG was defined as without any STDV, abnormal QRS morphology in lead V1 and S1Q3T3. Results: From a total of 210 patients with NTW, 131 had STDV ≥ 0.1 mV, while 79 did not. Patients with STDV had worse evolution: higher incidence of dyspnea, hypotension, cardiogen­ic shock, intensification of therapy, and death compared to patients without STDV (p = 0.001 for each variable). The majority (89%) of the patients with STDV presented with 1 of the 3 typical ischemic ECG patterns. LV subendocardial ischemic pattern (OR = 4.963, p = 0.004), RV transmural ischemic pattern (OR = 3.128, p = 0.021) and LV subendocardial plus RV transmural ischemic pattern (OR = 3.036, p = 0.017) independently predicted the need to intensify therapy. RV transmural ischemic pattern (OR = 4.227, p = 0.031) and LV subendocardial plus RV transmural ischemic pattern (OR = 4.022, p = 0.032) independently predicted 30-day mortality. Compared to the patients with abnormal ECG, the patients with relatively normal ECG had a significant lower incidence of death (0% vs. 16%; p = 0.001) and need to intensify therapy during hospitalization (6% vs. 30%; p = 0.002). Conclusions: Ischemic ECG patterns are common ECG manifestations of APE and predict worse evolution and 30-day mortality. Additionally, relatively normal ECGs may associate with favorable clinical outcomes.

The recent introduction of quadripolar leads for cardiac resynchronization therapy raises the question which pacing vector is most beneficial to response and which parameter gives insight into the optimal vector. The study conducted by Trolese et al. is therefore of important value and unique in its kind.1 The found correlation between maximal difference of the QRS-width (ΔQRS) and acute haemodynamic response (AHR) (ΔLV d P /d t max) is an important finding to aid vector selection. However, their results give rise to questions. Figure 1A of Trolese et al. shows an equal QRS morphology comparing M3M2 and M3P4 indicating cathodal stimulation from M3 and no effect of the anodal electrode. However, comparing D1M2 …

Introduction: Right ventricular (RV) anodal capture (AC) has been reported in cardiac resynchronization therapy (CRT), when left ventricular (LV) pacing uses pseudobipolar (LV tip to RV proximal electrode) configuration. The aim of the study was to analyze the prevalence of AC and its implications for device programming. Methods and Results: When AC occurred, the resulting QRS morphology was evaluated with the following pacing modes: (1) LV tip pacing plus RV AC, (2) Biventricular (BiV) pacing (i.e., both LV and RV tip pacing), and (3) BiV pacing plus RV AC. Several interventricular pacing (VV) intervals from 50 ms of LV preactivation to 30 ms of RV preactivation were tested in modes 2 and 3. From 38 consecutive patients, AC was achieved in 14 (in 74% of the pacemakers and in none of the defibrillators). LV tip pacing plus RV AC obtained narrower QRS than BiV pacing at all VV intervals in seven of the patients with AC (50%). When BiV pacing is combined with RV AC, it produced a ventricular depolarization through two wave fronts (one from the LV tip and the second from either the ring or the tip of the RV lead depending on the VV interval programmed). Conclusions: AC obtained the narrowest QRS of all tested pacing modes in a significant proportion of patients undergoing CRT. Though the stimulus was delivered from three sites (BiV pacing plus RV AC mode), only two wave fronts of ventricular activation were seen by ECG.

A robust method is presented for electrocardiogram (ECG)-based estimation of the respiratory frequency during stress testing. Such ECGs contain highly nonstationary noise and exhibit changes in QRS morphology which, when combined with the dynamic nature of the respiratory frequency, make most existing methods break down. The present method exploits the oscillatory pattern of the rotation angles of the heart's electrical axis as induced by respiration. The series of rotation angles, obtained from least-squares loop alignment, is subject to power spectral analysis and estimation of the respiratory frequency. Robust techniques are introduced to handle the nonstationary properties of exercise ECGs. The method is evaluated by means of both simulated signals, and ECG/airflow signals recorded from 14 volunteers and 20 patients during stress testing. The resulting respiratory frequency estimation error is, for simulated signals, equal to 0.5% /spl plusmn/ 0.2%, mean /spl plusmn/ SD (0.002 /spl plusmn/ 0.001 Hz), whereas the error between respiratory frequencies of the ECG-derived method and the airflow signals is 5.9% /spl plusmn/ 4% (0.022 /spl plusmn/ 0.016 Hz). The results suggest that the method is highly suitable for analysis of noisy ECG signals recorded during stress testing.

We successfully performed radiofrequency catheter ablation (RFCA) in 2 cases involving patients with idiopathic ventricular tachycardias (VTs) and premature ventricular contractions (PVCs) originating from the pulmonary artery (PA). The QRS morphology of the VTs and PVCs in the two cases exhibited a left bundle-branch block (LBBB) morphology with an inferior axis. Activation and pace mappings were performed in the right ventricular outflow tract (RVOT) and above the pulmonary valve to determine the origin of the VTs and PVCs. In both cases, the earliest ventricular activation was recorded in the PA above the pulmonary valve. Applications of radiofrequency current at those sites in the PA resulted in the elimination and noninducibility of the VT and PVC. During the follow-up, the VT or PVC did not recur without any antiarrhythmic drug administration.

We present the interesting case of a young man with borderline wide QRS complexes noted on electrocardiogram (ECG). The diagnosis of an unusual form of preexcitation was reached using observations from intracardiac tracings at electrophysiology study. Atrial pacing consistently resulted in further widening of the first conducted QRS complex, and the physiology underlying this unusual finding is explored.

VAN GELDER, B.M., ET AL.: The Effect of Anodal Stimulation on V-V Timing at Varying V-V Intervals. We studied the effect of anodal capture at the ring electrode of the right ventricular (RV) lead on interventricular (V-V)timing during biventricular (BiV) pacing, in which left ventricular (LV) pacing was preceding RV pacing. The V-V interval was programmed from 80 to 4 ms (LV first) in the LV unipolar (LV tip-generator can) followed by the LV tip-RV ring pacing configuration. In the LV unipolar configuration, V-V programming leads to a continuous change in morphology of the QRS complex according to a change in collision of both activation fronts. When using the LV tip-RV ring configuration with anodal capture at the RV ring electrode no change in QRS morphology was recorded varying the V-V interval from 80 to 60 and 40 ms. However, at V-V intervals between 20 and 4 ms a change in morphology of the QRS complex was recorded, which was due to additional cathodal stimulation of the RV tip electrode during RV stimulation.

To the Editor: Cardiac resynchronization therapy (CRT) improves symptoms and decreases hospitalizations in selected patients with heart failure ([1,2][1]). With CRT, pacing from the left ventricle (LV) alters the ventricular activation (VA) sequence, changing the QRS morphology. In responders

Electrocardiographic (ECG) artifacts resulting from misplacements of electrodes are frequent, difficult to detect, and can become of clinical importance. We investigated 2 healthy volunteers and 3 patients with ECG signs of inferior myocardial scars. We exchanged the peripheral electrodes in a defined manner and investigated the resulting ECG for morphology and possible diagnostic errors. In the volunteers, ECG signs of inferior ischemia could be produced. In the patients with ischemic heart disease, normal ECG without signs of ischemia resulted by placing the electrode of the left leg to the left arm. The automatic ECG analyzer was not helpful in detecting artifacts by misplaced electrodes. A very low amplitude of the QRS complex in lead I, II, or III was pathognomonic for electrode misplacement in half of the cases. ECG artifacts must also be suspected when abnormal QRS- or P-axis occur or when QRS morphology does not match with the clinical presentation of the patient.

Changing axis deviation has been reported also during atrial fibrillation or atrial flutter. Changing axis deviation has been also reported during acute myocardial infarction associated with atrial fibrillation too or at the end of atrial fibrillation during acute myocardial infarction. Left bundle branch block is usually associated with normal or left axis deviation. Rarely the ECG shows a left bundle branch block with changing QRS morphology and changing axis deviation. We present a case of a left bundle branch block with changing axis deviation in an 86-year-old Italian man admitted to the Cardiology Unit with an acute myocardial infarction. Also this case focuses attention on left bundle branch block with changing axis deviation.

Changing axis deviation has been reported also during atrial fibrillation or atrial flutter. Changing axis deviation has been also reported during acute myocardial infarction associated with atrial fibrillation too or at the end of atrial fibrillation during acute myocardial infarction. Left bundle branch block is usually associated with normal or left axis deviation. Rarely the ECG shows a LBBB with changing QRS morphology and changing axis deviation. There are several possible explanations for the intermittent shift in the QRS axis in the presence of complete left bundle branch block. The most plausible explanation is the coexistence of left posterior hemiblock and predivisional left bundle branch block. We present a case of a left bundle branch block with changing axis deviation in a 93-year-old Italian woman admitted to the Cardiology Unit with an acute myocardial infarction.

MOTS CLES Syndrome de WolfA 25-year-old man was admitted to hospital for electrophysiological studies for WolfParkinson-White syndrome, discovered during a medical clearance examination to be a professional soccer referee. This athlete had no medical history, reported no symptoms and his physical examination was normal. A 12-lead electrocardiogram revealed the presence of ventricular pre-excitation, a negative delta wave in leads I and aVL, and right bundle branch-type QRS morphology, consistent with a left lateral accessory pathway (Fig. 1), which persisted during peak exercise. Electrophysiological studies confirmed the presence of a left lateral accessory pathway and the induction of atrial fibrillation by rapid atrial pacing, immediately followed by the development of ventricular fibrillation (Fig. 2a, b), requiring the delivery of two consecutive biphasic 200J DC shocks to restore sinus rhythm (Fig. 3a). The patient

This article reports a new, transient, but identical electrocardiogram presentation in 2 patients at 2 different institutions. While its mechanism is uncertain, analysis by exclusion suggests that a diffusely prolonged but nonhomogenous myocardial refractoriness may have altered both QRS morphology and amplitude and also may have resulted in periods of 2:1 AV block.

“ Mahaim” Automatic Tachycardia. A series of four patients with right-sided accessory pathways with long conducting times and decremental properties is reported. All patients underwent radiofrequency catheter ablation, and target areas were guided by a discrete “ Mahaim” potential recorded at the lateral aspect of the tricuspid valve. A slow automatic and irregular rhythm with a QRS morphology similar to that of a fully preexcited QRS complex occurred during radiofrequency current delivery. The occurrence of so-called “ Mahaim” automatic tachycardia heralded successful elimination of the accessory pathway in a manner similar to that of junctional automatic rhythm during slow pathway ablation in patients with AV nodal reentrant tachycardia. The observation of an automatic rhythm brought about during radiofrequency current ablation of a Mahaim-like accessory pathway is electrophysiologic evidence of the accessory AV nodal behavior of this structure. (J Cardiovasc Electrophysiol, Vol. 13, pp.

Background Implantable cardiac monitors (ICMs) are valuable tools for long-term ECG monitoring, especially for AF. However, AF detection algorithms based solely on R-R interval variability are prone to a high number of false positives due to ectopic beats and noise. Objective The purpose of this analysis is to report on the simulated performance of an AF algorithm when using QRS morphology information. Methods Twelve-lead ECG data from 487 patients from 6 different clinical studies (collected in both in-clinic and ambulatory settings), including 35 AF patients, were used to evaluate the AF algorithm. The ECG vector V2–V3 was used to approximate the implanted ICM electrode configuration. The algorithm made a classification of AF or Non-AF for every 2-min window. Morphology Evaluation: The V2–V3 signal morphology of each detected beat in the 2-min window was compared against a QRS template built during sinus rhythm. A match score was assigned to each beat based on the similarity to the template. The percentage of mismatched beats per 2-min window (for example, due to noise or ectopic beats) was used to determine the degree of R-R interval variability not associated with AF. The user-programmed levels for ectopy rejection and AF sensitivity will determine the thresholds used to reject potential AF rhythms. Results A total of 44,716 2-min windows were evaluated. Morphology information was available in 228 windows of true AF along with 51 windows of false positives for AF. Morphology assessment was not conducted for 4 patients in persistent AF throughout the data recording (i.e. no sinus rhythm). Using the morphology evaluation, the results ranged from 41.2% reduction in false positives (21/51 windows) with no impact on sensitivity, to 56.9% (29/51 windows) reduction in false positives with a cost of missing 5 true AF windows (97.8% sensitivity) depending on how the ectopy rejection level is tuned. Conclusions Assessment of EGM morphology in an ambulatory AF detection algorithm can meaningfully reduce false positives with minimal impact to sensitivity.