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Introduction: The accuracy of surface ECG algorithms for predicting the origin of outflow tract ventricular arrhythmias (OT‐VAs) might be questioned. Intracardiac electrograms recorded at anatomic landmarks could provide new predictive insights. We aim to evaluate the efficacy of a novel criterion utilizing the activation pattern of the coronary sinus (CS) in localizing OT‐VAs, including VAs originating from the right ventricular outflow tract (RVOT), endocardial left ventricular outflow tract (Endo‐LVOT), and epicardial left ventricular outflow tract (Epi‐LVOT). Methods: We measured the ventricular activation time of the mitral annulus (MA) from the onset of the earliest QRS complex of VAs to the initial deflection over the isoelectric line at local signals, namely the QRS‐MA interval. The activation at 3 and 12 o'clock of the MA was recorded as the QRS‐MA3 and QRS‐MA12 intervals, respectively. Their predictive values were compared to previous ECG algorithms. Results: A total of 68 patients with OT‐VAs were enrolled (51 for development and 17 for validation). From early to late, the ventricular activation sequences at MA12 were as follows: Epi‐LVOT, Endo‐LVOT, and RVOT. In LBBB morphology OT‐VAs, the QRS‐MA12 interval was significantly earlier for LVOT origins than RVOT origins. In the combined cohort of development and validation cohort, a cut‐off value of ≤10 ms predicted the LVOT origin with a sensitivity of 100% and specificity of 78%. The QRS‐MA12 interval ≤ −24 ms additionally predicted epicardial LVOT sites of origin. Conclusions: The QRS‐MA interval could accurately differentiate the OT‐VAs localization. [ABSTRACT FROM AUTHOR]

Introduction: Our team once proposed a correction of transitional zone index (CTZI) based on the transitional zone index (TZI) in view of achieving a more precise prediction of outflow tract ventricular arrhythmia (OTVA). The predictive accuracy of these two electrocardiogram (ECG) algorithms has not been validated and compared. The purpose of this study was to compare the predictive accuracy of TZI and CTZI in a much larger population with idiopathic OTVA. Methods: The predictive accuracy of TZI and CTZI was compared in 695 individuals with idiopathic premature ventricular complex or ventricular tachycardia which exhibited a left bundle branch block pattern and inferior axis QRS morphology. Receiver operating characteristic curve analysis, decision curve analysis, and calibration curve were used to compare the predictive accuracy of TZI and CTZI. Results: TZI and CTZI manifested the similar area under the curve. While a TZI of <0 predicted a left ventricular outflow tract (LVOT) origin with a high specificity of 88.2% but a low sensitivity of 67.1%, a CTZI of <0 yielded a high sensitivity of 84.3% but a low specificity of 59.5% in the overall analysis. Similar results were yielded in the sub-analysis of participants with a precordial transition occurring at lead V3. In the sub-analysis of participants with a TZI = 0, CTZI demonstrated a bit higher but not satisfactory predictive accuracy than TZI. Conclusion: Based on the scientific spirit of self-criticism and seeking truth from facts, our team disproves the correction of TZI proposed previously. [ABSTRACT FROM AUTHOR]

Background: As an indicator of cardiac autonomic nervous activity, heart rate variability (HRV) is closely linked to premature ventricular complexes (PVCs). However, its role in patients with frequent PVCs originating from the ventricular outflow tract remains unclear. Hypothesis: Here, we hypothesize that there may be alterations in HRV among patients with frequent PVCs originating from the ventricular outflow tract, which could play significant roles in the management of such patients. Methods: A retrospective study was conducted, including 106 patients with frequent outflow tract PVCs and 106 healthy participants as controls. HRV was assessed based on the 24‐hour Holter recording. The originating foci of PVCs were identified during radiofrequency catheter ablation. Results: Patients with frequent outflow tract PVCs exhibited decreased levels of high frequency (HF), standard deviation of all NN intervals, and standard deviation of the average NN intervals, but increased ratios of low frequency to HF (LF/HF ratio), even after propensity score‐matched analysis. Further investigation revealed that patients with PVCs originating from right ventricular outflow tract (RVOT) had much higher LF/HF ratios. Multivariate logistic regression analysis demonstrated that the LF/HF ratio was independently associated with PVCs originating from RVOT. Receiver operating characteristics curve indicated that the LF/HF ratio effectively determined the origin of PVCs (the area under the curve = 0.75, p <.001). Conclusions: Patients with frequent outflow tract PVCs exhibited impaired HRV. Additionally, the LF/HF ratio played a significant role in determining the origin of outflow tract PVCs. [ABSTRACT FROM AUTHOR]

Background: The features of the unipolar electrogram (UEGM) and bipolar electrogram (BEGM) have been utilized to identify the site of origin of idiopathic premature ventricular contractions (PVCs) arising from pulmonary sinus cusps (PSCs), but for these PVCs, whether a negative concordance in the initial waves of both EGMs recorded above pulmonary valves can be used as a parameter to localize the origin has not been previously studied. We aimed to assess whether an initial negative concordance (INC) between the UEGM and BEGM might determine the origin of PVCs mapped and ablated within PSCs. Methods: Data were collected from 22 patients undergoing successful radiofrequency catheter ablation for symptomatic idiopathic PVCs within PSCs. The morphological features of both the UEGM and the BEGM recorded at all ablation sites were analyzed. Results: A total of 109 sites within PSCs were ablated in 22 patients with an age (mean ± SD) of 47.2 ± 17.2 years. Ablation resulted in procedural success in all patients. The INC was observed at 18 of 22 (81.8%) successful ablation sites, contrasted with 3 of 87 (3.4%) unsuccessful sites (P < 0.001). The INC was consistent with the outcomes of conventional mapping parameters and proved to be an additional useful predictor of ablation success, with a sensitivity, specificity, positive predictive value and negative predictive value of 81.8%, 96.6%, 85.7% and 95.5%, respectively. Conclusions: An INC between the UEGM and the BEGM can predict the origin of PVCs arising from PSCs. An initial negative concordance between unipolar and bipolar electrograms indicates that the distal electrode of the ablation catheter is at the origin of premature ventricular contractions within pulmonary sinus cusps. [ABSTRACT FROM AUTHOR]

Abstract Background Mastering cardiac anatomy is a formidable obstacle in the learning process for cardiac electrophysiology trainees. The complex three-dimensional characteristics and contiguous relationship of the ventricular outflow tract are particularly difficult to visualize with the limited study methods available. The hands can recreate a morphology similar to the ventricular outflow tract; this study explored whether a two-handed model of the heart helps electrophysiology trainees improve their understanding of ventricular outflow tract anatomy. Methods After an initial assessment, trainees were randomly placed into variable and control groups. Subsequently, all trainees learned the outflow tract anatomy using routine methods, with the variable group receiving additional instruction using the two-handed model. One day and one week after the course conclusion, knowledge of the ventricular outflow tract anatomy was assessed for the participants in both groups. Results Thirty-eight trainees participated (19 in each group). The median scores obtained for the first, second, and third tests were 38 (24,55), 80 (70,86), and 75 (70,81) points, respectively. In the second test, trainees in the variable group had a mean score 6.8 points higher than those in the control group (p = 0.103); in the last test, the mean score was 9.7 points higher in the variable group than in the control group (p = 0.003). Conclusions It is convenient to use hands to create a model representing the ventricular outflow tract. Trainees using this model had a better understanding and retention of the ventricular outflow tract anatomy compared to those of the control group.

Background: Mastering cardiac anatomy is a formidable obstacle in the learning process for cardiac electrophysiology trainees. The complex three-dimensional characteristics and contiguous relationship of the ventricular outflow tract are particularly difficult to visualize with the limited study methods available. The hands can recreate a morphology similar to the ventricular outflow tract; this study explored whether a two-handed model of the heart helps electrophysiology trainees improve their understanding of ventricular outflow tract anatomy. Methods: After an initial assessment, trainees were randomly placed into variable and control groups. Subsequently, all trainees learned the outflow tract anatomy using routine methods, with the variable group receiving additional instruction using the two-handed model. One day and one week after the course conclusion, knowledge of the ventricular outflow tract anatomy was assessed for the participants in both groups. Results: Thirty-eight trainees participated (19 in each group). The median scores obtained for the first, second, and third tests were 38 (24,55), 80 (70,86), and 75 (70,81) points, respectively. In the second test, trainees in the variable group had a mean score 6.8 points higher than those in the control group (p = 0.103); in the last test, the mean score was 9.7 points higher in the variable group than in the control group (p = 0.003). Conclusions: It is convenient to use hands to create a model representing the ventricular outflow tract. Trainees using this model had a better understanding and retention of the ventricular outflow tract anatomy compared to those of the control group. [ABSTRACT FROM AUTHOR]

Idiopathic ventricular arrhythmias (VAs) most commonly originate from the ventricular outflow tracts. Because the anatomy of this region is complex and some of those VA origins are intramural and epicardial, it may sometimes be difficult to locate the site of the VA origin. Meticulous mapping in multiple different locations such as the right and left ventricular outflow tracts, endocardial and epicardial sites, and above and below the aortic and pulmonic valves may be required to achieve successful catheter ablation of those VAs. Special ablation techniques may be considered to improve the outcome of catheter ablation of intramural and epicardial VAs. [ABSTRACT FROM AUTHOR]

Aims: Our objective was to explore whether the accuracy of the transitional zone index (TZI) for outflow tract ventricular arrhythmias (OT‐VAs) origin is affected by cardiac rotation and the additive value of interventricular septum angle (IVSa) obtained from coronary computed tomography angiography (CCTA). Methods: Standard 12‐lead ECGs of OT‐VAs with inferior axis in consecutive patients undergoing both CCTA examination and successful ablation were retrospectively analyzed. The IVSa was defined as an angle between the long axis of IVS and sagittal axis of the body from CCTA. Results: 64 patients (31 men; mean age 54.2 ± 11.6 years) were enrolled. The OT‐VAs exhibited right ventricular outflow tract origin in 46 (71.9%) patients and 36 (78.3%) were diagnosed correctly by TZI. The left ventricular outflow tract origin OT‐VAs was observed in 18 (28.1%) patients and 16 (88.9%) were diagnosed correctly by TZI. The patients were then divided into TZI correct group (n = 52) and TZI incorrect group (n = 12). In the TZI incorrect group, 11/12 (91.7%) cases were R/S transition in lead V3 with the TZ score during premature ventricular contractions [2.8(2.5−3.4)], and the TZI between −1.5 and 0. The IVSa was significantly larger in the TZI incorrect group than correct group (52.0 ± 6.9° vs. 39.0 ± 6.1°; p <.0001). The IVSa ≥46° predicted TZI incorrect with 92% sensitivity, 94% specificity, and 94% accuracy. Conclusion: The IVSa is a novel cardiac rotation index that reliably improves TZI to differentiate the OT‐VAs origin, especially for the OT‐VAs with lead V3 R/S transition. [ABSTRACT FROM AUTHOR]

A 68-year-old patient with triple vessel coronary artery disease was scheduled for elective coronary artery bypass grafting. Three days after the uneventful surgery, the patient went into cardiogenic shock, which was deemed to be caused by a dynamic left ventricular outflow tract obstruction and high-grade mitral regurgitation, which both had not been present before surgery. On an emergency basis, surgical transvalvular septal myectomy and mitral valve replacement were performed. After initial extra corporeal membrane oxygenation (ECMO) therapy and a prolonged (intensive care unit) ICU stay the patient finally recovered and is well one and a half years after surgery.

Background: Outflow tract (OT) premature ventricular contractions (PVCs) are commonly found in clinical practice; in most cases, PVCs are benign and observed in structurally normal hearts, not requiring any therapeutic intervention. In this study, we therefore sought to evaluate with cardiac magnetic resonance (CMR) patients with PVC and apparently normal heart at echocardiographic examination, in order to identify possible substrates linked with higher prevalence of arrhythmias or structural heart disease.Methods: Thirty-three consecutive patients with frequent PVCs originating from the ventricular OT (right and left) were enrolled in the study and assessed by echocardiography and CMR. All patients had normal baseline electrocardiogram.Results: CMR showed structural changes in 5 patients out of 33; in 3 cases, areas of fibrosis limited in one case to the middle basal segments of the interventricular septum and in two patients to the middle basal segments of the inferior-lateral wall were found. In 2 other cases, however, late gadolinium enhancement showed significant anomalies characterized in one patient by extensive areas of subepicardial fibrosis of the left ventricle, suitable with arrhythmogenic left dominant dysplasia; in another patient, a marked trabeculation of left ventricular medium apical segments suitable with non-compaction myocardium was present.Conclusions: CMR may identify cases of structural heart disease in subjects with OT PVCs and apparently normal electrocardiogram and echocardiogram examinations. A preliminary screening with CMR may be considered before any further invasive electrophysiology assessment and therapeutic planning. [ABSTRACT FROM AUTHOR]

Objectives. Catheter ablation is an effective method in the treatment of idiopathic ventricular arrhythmias. The mapping methods used for predicting the original site of arrhythmias are difficult to use and time-consuming. Consequently, developing methods using surface ECG for guiding the location is important. Here, we have tested a new ECG criterion to differentiate the left from the right ventricular originated complexes (PVCs) or tachycardias (VTs). Designs. Sixty patients with idiopathic PVC or VT who had undergone a successful radiofrequency catheter ablation (RFA) of arrhythmia were enrolled. The surface ECG during sinus rhythm and arrhythmia was analyzed. Initial r wave Surface Area (ISA) index was measured by multiplying the R wave duration in milliseconds by the R wave amplitude in terms of millivolt in V1 or V2 leads. Results. Thirty-seven patients with right ventricular (RVOT) and 23 with left ventricular outflow tract (LVOT) originated VT or PVC were enrolled. The ISA index was significantly greater in LVOT-VT/PVC compared to RVOTs (63.6 ± 78.9 vs. 8.3 ± 7.3, p < .001). With a cut off value of ≥15, the index could differentiate a left from right arrhythmia with 94.6% specificity and 78.2% sensitivity (Area on the curve, 0.81; p < .001). Compared to other previously reported indices, ISA is the most specific one. Conclusion. ISA index can serve as a very useful ECG criterion for differentiating a LVOT- from RVOT-originated VTs or PVCs. [ABSTRACT FROM AUTHOR]

Purpose: Idiopathic outflow tract ventricular arrhythmias are ventricular tachycardias or premature ventricular contractions presumably not related to myocardial scar or disorders of ion channels. These arrhythmias have focal origin and display characteristic electrocardiographic features. The purpose of this article is to review the state of the art of diagnosis and treatment of idiopathic outflow tract ventricular arrhythmias.Methods: We systematically reviewed scientific literature about idiopathic outflow tract ventricular arrhythmias selecting the most relevant papers on this topic.Results: The right ventricle outflow tract is the most common site of origin for outflow tract ventricular arrhythmias, but also left ventricle outflow tract can harbour these arrhythmias. Outflow tract ventricular arrhythmias are generally benign and may require treatment if they are symptomatic, incessant or give rise to cardiomyopathy. Radiofrequency catheter ablation is an effective and safe therapeutic strategy. A successful procedure requires a thorough preoperative analysis of the 12-lead electrocardiogram of the spontaneous arrhythmia combined with a detailed electroanatomical mapping and intracardiac echocardiography.Conclusions: Idiopathic outflow tract arrhythmias are frequent in daily clinical practice and can be successfully eliminated through discrete radiofrequency catheter ablation with low rates of complications. [ABSTRACT FROM AUTHOR]

Abstract Background Ventricular outflow tract(VOT) ventricular arrhythmias(VAs) presenting qrS pattern or QS pattern with a notch on the descending limb in lead V1 were consistently thought of arising from the commissure between left and right coronary cusp (L-RCC) by previous studies. However, we found they could originate from other anatomic structures in VOT. This study aimed to investigate the exact origin of this kind VAs. Methods Forty-nine patients of VOT premature ventricular contrations/ventricular tachycardia(PVCs/VT) with lead V1 presenting qrS pattern or QS pattern with a notch on the descending limb undergoing successful radiofrequency catheter ablation(RFCA) in our center were analyzed. Results 12-lead electrocardiogram(ECG) of these PVCs/VT were summarized. Among these PVCs/VT, 37 cases exhibited qrS morphology in lead V1, 12 cases presented QS pattern with a notch on the descending limb in the same lead. Based on the successful ablation sites, these PVCs/VT were divided into 2 groups: (1)Right ventricular outflow tract(RVOT) group (26 cases), and (2) Left ventricular outflow tract (LVOT) group(23 cases, 4 cases originating from the left coronary cusp(LCC), 2 from the right coronary cusp(RCC), 16 from the L-RCC, 1 from the area inferior to LCC(ILCC)). The ECG characteristics of each PVCs/VT were analyzed. Among these PVCs/VT, applying the precordial transitional zone index(TZ index)

Purpose: The aim of this study was to develop a new electrocardiographic criterion for differentiating the origin of outflow tract ventricular arrhythmias (OT-VAs) with precordial transition in lead V3.Methods: A total of 147 consecutive patients with OT-VAs displaying precordial transition in lead V3 who underwent successful catheter ablation in the right ventricular outflow tract (RVOT) (n = 118) or left ventricular outflow tract (LVOT) (n = 29) were included in this study. The V1-V3 transition index was defined as the sum of S-wave amplitude in lead V1 and V2 during premature ventricular contractions (PVCs) divided by the S-wave amplitude during sinus rhythm (SR), respectively, minus the sum of R-wave amplitude in lead V1, V2, and V3 during PVCs divided by the R-wave amplitude during SR, respectively, i.e., [(SPVC/SSR)V1 + (SPVC/SSR)V2] - [(RPVC/RSR) V1 + (RPVC/RSR)V2 + (RPVC/RSR)V3].Results: The V1-V3 transition index was significantly higher for RVOT origins than for LVOT origins (1.25 ± 2.48 vs. - 3.94 ± 3.11; P < 0.001). Receiver operating characteristic (ROC) analysis revealed an area under the curve (AUC) of 0.931 for the V1-V3 transition index, and a cutoff value of > - 1.60 predicted a RVOT origin with a 93% sensitivity and 86% specificity. With respect to AUC and accuracy, the V1-V3 transition index was superior to any previously proposed ECG indices for differentiating left from right OT-VAs. In 37 prospective cases, the new index was able to predict the site of a RVOT origin with 95% accuracy (35 of 37 cases).Conclusions: The V1-V3 transition index is a useful novel ECG criterion for distinguishing left from right OT-VAs with precordial transition in lead V3. [ABSTRACT FROM AUTHOR]

Background: Data regarding the successful ablation site of idiopathic outflow tract (OT) ventricular arrhythmias (VAs) in the modern era of mapping and ablation are limited.Methods and Results: Over a 4-year period, a total of 309 patients underwent detailed activation mapping of OT VAs including the right ventricular outflow tract (RVOT), the left ventricular outflow tract (LVOT) and the aortic cusps (AC), and the coronary venous system. 244 cases were successfully ablated at the index procedure (78.9%). The successful ablation site was more frequently located at the LVOT/ACs (51.6%) followed by RVOT (36.2%). In particular, the ACs was the predominant successful ablation site of idiopathic OT VAs (46.7%). An epicardial site of origin was predictor of ablation failure (p < 0.05).Conclusions: The ACs is the predominant successful ablation site of idiopathic OT VAs.Take-home Message: The aortic cusps are the predominant successful ablation site of idiopathic idiopathic outflow tract ventricular arrhythmias. [ABSTRACT FROM AUTHOR]

Abstract: Idiopathic sustained focal right ventricular tachycardia (VT) is most frequently due to outflow tract (OT) tachycardia. This arrhythmia is recognized by its characteristic ECG pattern and sensitivity to adenosine. However, there are other forms of idiopathic, focal sustained VT that originate from the right ventricle (RV), which are less well appreciated and easily overlooked. This review will identify the characteristic features and electrophysiologic properties of these forms of RV VT, including those originating from the tricuspid annulus, right ventricular papillary muscles, and moderator band as well as variants of classic RVOT tachycardia and those due to microreentry in the presence of preclinical disease. Recognition of these subtypes of focal RV tachycardia should facilitate targeted therapy. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Although several electrocardiographic (ECG) algorithms have been proposed for differentiating the origins of outflow tract ventricular arrhythmias, the most optimal one has not been agreed on. The purpose of this study was to establish an ECG diagnostic model based on the previous ECG algorithms. Methods and results: The following ECG diagnostic model, Y = − 1.15 × ( TZ ) − 0.494 × ( V 2 S / V 3 R ), was developed by standard 12‐lead ECG algorithms in 488 patients with idiopathic premature ventricular contractions or ventricular tachycardia with a left bundle branch block pattern and inferior axis QRS morphology. Binary logistic regression analysis was performed to establish the ECG diagnostic model. The ECG diagnostic model consisted of two ECG algorithms—the transition zone (TZ) index and V2S/V3R index. The area under the curve by receiver operating characteristic curve analysis for the ECG diagnostic model was 0.88, with a cut‐off value of ≥ –0.76 predicting a left ventricular outflow tract (LVOT) origin with a sensitivity of 82% and a specificity of 86%, which was higher than other ECG algorithms in this study. The predictive accuracy of the ECG diagnostic model was also the best among all ECG algorithms in patients with a lead V3 precordial transition. This model was tested prospectively in 207 patients with a sensitivity of 90%, a specificity of 87%, and Youden index of 0.77. Conclusions: A highly accurate ECG diagnostic model for correctly differentiating LVOT origin from right ventricular outflow tract origin was developed. [ABSTRACT FROM AUTHOR]

Background: Outflow tract ventricular tachycardias (OTVT) most commonly occur in the absence of structural abnormalities. We present two cases in which a structural variant in the outflow tract was critical to the OTVT. Cases: Subaortic muscular bands were identified using intracardiac echocardiography (ICE) in each of our cases with history of VSD and VT. Mapping demonstrating their critical involvement to the tachycardia and ablation along the muscular bands rendered the ventricular tachycardias non‐inducible. Conclusion: In rare instances, a structural variant may be involved in OTVTs. The use of ICE along with electroanatomic mapping can assist in successful ablation of these ventricular tachycardias. [ABSTRACT FROM AUTHOR]

The article presents a commentary on a study which developed a unique electrocardiography (ECG) algorithm for the prediction of a ventricular arrhythmia (VA) origin that is likely to be ablated within the left coronary cusp (LCC) or right coronary cusp (RCC) by combining several ECG algorithms proposed previously. Topics covered include use of ECG characteristics in predicting the site of idiopathic VA, and successful ablation of VA in the left pulmonary sinus cusp (PSC).

Aims: One of the disadvantages of classic pace mapping (PM) is the operator's subjective interpretation. The aim of this single-centre retrospective study was to evaluate the value of automated template matching (AMT) in patients ablated due to ventricular outflow tract arrhythmias (OTAs).Methods and Results: From an overall group of 105 patients with OTA who were scheduled for transcatheter ablation (TA), AMT was accessible in 42 patients [21 right ventricular outflow tract (RVOT), 21 left ventricular outflow tract (LVOT), 28 women, aged 51.5 ± 12.7 years]. We used AMT to compare spontaneous arrhythmia ORS (spontQRS) with paced QRS complexes during PM in sites where radiofrequency (RF) applications were successful and in sites where RF applications were unsuccessful. The concordance was presented in per cents as objective matching scores (OMS). Then, at the successful ablation sites, we examined the relationship between OMS and the visual interpretation of PM was presented as electrophysiologists matching scores (EMS). The OMS of PM at sites of successful ablation varied from 78 to 99% (mean 94.1 ± 3.8) and from 47 to 95% (mean 80.2 ± 12.6%) at sites of unsuccessful ablation. Pace mapping in unsuccessful RF sites was significantly less similar to spontQRS morphologies than in successful RF sites (P = 0.0001). There was a significant correlation between OMS and EMS (r = 0.82; P < 0.0001). The OMS that indicated optimal ablation site was 89% (sensitivity = 95%; specificity = 80%). The mean OMS for successful sites at RVOT (95.1 ± 1.8%) and LVOT (93.1 ± 4.9%) were not different (P = 0.0551).Conclusion: This analysis revealed that AMT is a valuable technique for the interpretation of PM and for the identification of successful ablation sites in OTA. [ABSTRACT FROM AUTHOR]

V2S/V3R Index Distinguishes LVOT from RVOT Origins Introduction Although several ECG criteria have been proposed for differentiating between left and right origins of idiopathic ventricular arrhythmias (VA) originating from the outflow tract (OT-VA), their accuracy and usefulness remain limited. This study was undertaken to develop a more accurate and useful ECG criterion for differentiating between left and right OT-VA origins. Methods and Results We studied OT-VAs with a left bundle branch block pattern and inferior axis QRS morphology in 207 patients who underwent successful catheter ablation in the right (RVOT; n = 154) or left ventricular outflow tract (LVOT; n = 53). The surface ECGs during the OT-VAs and during sinus beats were analyzed with an electronic caliper. The V2S/V3R index was defined as the S-wave amplitude in lead V2 divided by the R-wave amplitude in lead V3 during the OT-VA. The V2S/V3R index was significantly smaller for LVOT origins than RVOT origins (P < 0.001). The area under the curve (AUC) for the V2S/V3R index by a receiver operating characteristic analysis was 0.964, with a cut-off value of ≤1.5 predicting an LVOT origin with an 89% sensitivity and 94% specificity. In the AUC and accuracy, the V2S/V3R index was superior to any previously proposed ECG criteria in an analysis of all OT-VAs. This advantage of the V2S/V3R index over the V2 transition ratio and other indices also held true for a subanalysis of 77 OT-VAs with a lead V3 precordial transition. Conclusion The V2S/V3R index outperformed other ECG criteria to differentiate left from right OT-VA origins independent of the site of the precordial transition. [ABSTRACT FROM AUTHOR]

Background: Frequent ventricular premature depolarizations (VPDs) can cause cardiomyopathy (CMP). The mechanisms underlying its development remain unclear, with VPD burden being only a weak predictor of risk. Objective: To determine whether VPD QRS duration at the time of initial presentation could predict risk for the subsequent development of CMP in patients with normal left ventricular ejection fraction (LVEF). Methods: From consecutive patients referred for ablation between January 1, 2006, and April 2, 2013, with ≥10% VPDs on 24-hour Holter monitoring, we identified 45 patients with normal LVEF and an electrocardiogram of the targeted VPD, who were then followed for at least 6 months (median 14 months; interquartile range [IQR] 8–32 months) before intervention. We excluded patients with structural or genetic heart disease. Results: Of the 45 patients, 28 (62%) maintained normal LVEF and 17(38%) developed VPD-induced CMP. VPD burden was similar (26.5% [IQR 19.3%–39.5%] vs 26.0% [IQR 16.4%–41.0%]; P = 0.4) between the 2 groups. Patients who developed VPD-induced CMP had significantly longer VPD QRS duration (159 ms vs 142 ms; P < .001) and a longer sinus QRS duration (97 ms vs 89 ms; P = .04). A VPD QRS duration of ≥153 ms best predicted development of VPD CMP (82% sensitivity and 75% specificity). Longer VPD QRS duration and a non–outflow tract site of VPD origin were independent risk factors for left ventricular dysfunction after multivariate analysis. Conclusion: VPD QRS duration longer than 153 ms and a non–outflow tract site of origin might be useful predictors of the subsequent development of VPD-induced CMP. [Copyright &y& Elsevier]

Identification of Ventricular Outflow Tract Tachycardia. Background: Reentrant ventricular outflow tract (OT) tachycardia is rare in patients with nonischemic heart disease. The mechanism of ventricular tachycardia (VT) arising from the region of the aortic sinus of Valsalva (ASOV) is usually focal, rather than reentrant. Consequently, less is known about reentrant circuits in the OT and the aortic sinuses. The purpose of this study was to evaluate existence of reentry circuits in these areas using entrainment mapping techniques. Methods: We performed electrophysiological study in 51 consecutive patients with idiopathic or nonischemic symptomatic VT arising from the OT. Six of these patients were found to have VT of reentrant mechanism with 8 VT morphologies. Entrainment mapping, electroanatomical mapping (in 2 patients), and radiofrequency catheter ablation were performed. Results: Pacing entrained the VT at 93 sites, 52 of which were determined to be in the reentry circuit based on matching of the postpacing interval and VT cycle length. Of the reentry circuit sites, 6 were in the aortic sinus, 43 were below the aortic valve, and 3 were in the right OT below the pulmonary valve. Classification of reentry circuit sites identified 7 as exit, 1 as central-proximal, 19 as inner loop, and 25 as outer loop sites. Catheter ablation terminated VT at 4 of the 6 aortic sinus sites and 4 of the 46 OT sites (P = 0.0006). Conclusions: We definitively demonstrated involvement of the ASOV in OT reentrant tachycardia using entrainment mapping. It may be useful for successful VT ablation to identify reentry circuit localization. (J Cardiovasc Electrophysiol, Vol. 23, pp. 179-187, February 2012) [ABSTRACT FROM AUTHOR]

Our objective was to determine the normal dimensions of the ventricular segment of the human fetal heart between 13 and 20 weeks' gestation. Study Design: 103 hearts obtained by necropsy were dissected and measurements of different portions of ventricles were determined under stereoscopic magnification. In each ventricle were measured anteroposterior and lateral diameters, inlet and outlet length, and thickness of walls at different levels. Our results showed the cardiac apex was constituted by the left ventricle in 68.9% of the hearts. Both ventricles showed linear growth during this period of fetal development. Ranges in median values of external and internal ventricular measurements were determined. The left ventricular wall was thicker than the right, and the right ventricular cavity was larger. This study provides morphometric reference information concerning the dimensions and growth of both ventricles of the fetal heart, which may be useful in pediatric cardiac surgery and echocardiography. [ABSTRACT FROM AUTHOR]

The long-term characteristics of the right ventricular outflow tract have been assessed as an alternative permanent pacing site to the right ventricular apex. Thirty-three consecutive patients requiring ventricular pacing were randomized to he paced from one of the two sites. Pacing was performed using a screw-in lead, and a programmable pacemaker was used to facilitate threshold testing. There was no significant difference in the lead positioning time or any acute implant measurement (e.g., threshold at 0.5 msec 0.4 ± 0.2 V for both sites, P = 0.99). Chronic measurements were also comparable during follow-up (mean 73 months) with a mean threshold at most recent follow-up of 0.15 ± 0.2 msec (apex) and 0.13 ± 0.21 msec (outflow tract) at 5 V, P = 0.81. There was only one pacing related complication, a lead dislodgment (outflow tract) in a pacemaker twiddler. Overall, both sites were highly satisfactory. [ABSTRACT FROM AUTHOR]

A 22-year-old man was referred for palpitations. On transthoracic echocardiography, he was found to have a right ventricular outflow tract mass. Further cardiac imaging was conducted by means of transesophageal echocardiography, computed tomography, and cardiac magnetic resonance. Complete surgical resection of the tumor was achieved, and pathologic examination revealed the lesion to be a myxoma. Cardiac tumors located in the right ventricular outflow tract are rare and can present unusual diagnostic and therapeutic challenges. Cardiac computed tomography and magnetic resonance are becoming more widely available and can be useful adjuncts in the management of such tumors. [ABSTRACT FROM AUTHOR]