Lower sarcoplasmic reticulum Ca2+ threshold for triggering afterdepolarizations in diabetic rat hearts

BACKGROUND

Type 2 diabetes (T2D) increases arrhythmia risk through incompletely elucidated mechanisms. Ventricular arrhythmias could be initiated by delayed afterdepolarizations (DADs) resulting from elevated spontaneous sarcoplasmic reticulum (SR) Ca2+ release (SR Ca2+ leak).

OBJECTIVE

The purpose of this study was to test the role of DADs and SR Ca2+ leak in triggering arrhythmias in T2D hearts.

METHODS

We compared rats with late-onset T2D that display pancreatic and cardiac phenotypes similar to those in humans with T2D (HIP rats) and their nondiabetic littermates (wild type [WT]).

RESULTS

HIP rats showed higher propensity for premature ventricular complexes and ventricular tachyarrhythmias, whereas HIP myocytes displayed more frequent DADs and had lower SR Ca2+ content than WT. However, the threshold SR Ca2+ at which depolarizing transient inward currents (Itis) are generated was also significantly decreased in HIP myocytes and was below the actual SR Ca2+ load, which explains the increased DAD incidence despite reduced Ca2+ in SR. In agreement with these findings, Ca2+ spark frequency was augmented in myocytes from HIP vs WT rats, which suggests activation of ryanodine receptors (RyRs) in HIP hearts. Indeed, RyR phosphorylation (by CaMKII and protein kinase A) and oxidation are enhanced in HIP hearts, whereas there is no RyR O-GlcNAcylation in either HIP or control hearts. CaMKII inhibition dissipated the difference in Ca2+ spark frequency between HIP and WT myocytes.

CONCLUSION

The threshold SR Ca2+ for generating depolarizing Itis is lower in T2D because of RyR activation after hyperphosphorylation and oxidation, which favors the occurrence of DADs despite low SR Ca2+ loads.

Learning Domain Shift in Simulated and Clinical Data: Localizing the Origin of Ventricular Activation From 12-Lead Electrocardiograms

Building a data-driven model to localize the origin of ventricular activation from 12-lead electrocardiograms (ECG) requires addressing the challenge of large anatomical and physiological variations across individuals. The alternative of a patient-specific model is, however, difficult to implement in clinical practice because the training data must be obtained through invasive procedures. In this paper, we present a novel approach that overcomes this problem of the scarcity of clinical data by transferring the knowledge from a large set of patient-specific simulation data while utilizing domain adaptation to address the discrepancy between the simulation and clinical data. The method that we have developed quantifies non-uniformly distributed simulation errors, which are then incorporated into the process of domain adaptation in the context of both classification and regression. This yields a quantitative model that, with the addition of 12-lead ECG data from each patient, provides progressively improved patient-specific localizations of the origin of ventricular activation. We evaluated the performance of the presented method in localizing 75 pacing sites on three in-vivo premature ventricular contraction (PVC) patients. We found that the presented model showed an improvement in localization accuracy relative to a model trained on clinical ECG data alone or a model trained on combined simulation and clinical data without considering domain shift. Furthermore, we demonstrated the ability of the presented model to improve the real-time prediction of the origin of ventricular activation with each added clinical ECG data, progressively guiding the clinician towards the target site.

Isolated diastolic potentials as predictors of success in ablation of right ventricular outflow tract idiopathic premature ventricular contractions

Background and aims

Discrete potentials, low voltage and fragmented electrograms, have been previously reported at ablation site, in patients with premature ventricular contractions (PVCs) originating in the right ventricular outflow tract (RVOT). The aim of this study was to review the electrograms at ablation site and assess the presence of diastolic potentials and their association with success.

Methods

We retrospectively reviewed the electrograms obtained at the radiofrequency (RF) delivery sites of 48 patients subjected to ablation of RVOT frequent PVCs. We assessed the duration and amplitude of local electrogram, local activation time, and presence of diastolic potentials and fragmented electrograms.

Results

We reviewed 134 electrograms, median 2 (1–4) per patient. Success was achieved in 40 patients (83%). At successful sites the local activation time was earlier– 54 (-35 to -77) ms vs -26 (-12 to -35) ms, p<0.0001; the local electrogram had lower amplitude 1 (0.45–1.15) vs 1.5 (0.5–2.1) mV, p = 0.006, and longer duration 106 (80–154) vs 74 (60–90) ms, p<0.0001. Diastolic potentials and fragmented electrograms were more frequently present, respectively 76% vs 9%, p <0.0001 and 54% vs 11%, p<0.0001. In univariable analysis these variables were all associated with success. In multivariable analysis only the presence of diastolic potentials [OR 15.5 (95% CI: 3.92–61.2; p<0.0001)], and the value of local activation time [OR 1.11 (95% CI: 1.049–1.172 p<0.0001)], were significantly associated with success.

Conclusion

In this group of patients the presence of diastolic potentials at the ablation site was associated with success.

Noninvasive Imaging of Epicardial and Endocardial Potentials With Low Rank and Sparsity Constraints

In this study, we explore the use of low rank and sparse constraints for the noninvasive estimation of epicardial and endocardial extracellular potentials from body-surface electrocardiographic data to locate the focus of premature ventricular contractions (PVCs). The proposed strategy formulates the dynamic spatiotemporal distribution of cardiac potentials by means of low rank and sparse decomposition, where the low rank term represents the smooth background and the anomalous potentials are extracted in the sparse matrix. Compared to the most previous potential-based approaches, the proposed low rank and sparse constraints are batch spatiotemporal constraints that capture the underlying relationship of dynamic potentials. The resulting optimization problem is solved using alternating direction method of multipliers. Three sets of simulation experiments with eight different ventricular pacing sites demonstrate that the proposed model outperforms the existing Tikhonov regularization (zero-order, second-order) and L1-norm based method at accurately reconstructing the potentials and locating the ventricular pacing sites. Experiments on a total of 39 cases of real PVC data also validate the ability of the proposed method to correctly locate ectopic pacing sites.

PVC Detection Using a Convolutional Autoencoder and Random Forest Classifier

The accurate detection of premature ventricular contractions (PVCs) in patients is an important task in cardiac care for some patients. In some cases, the usefulness to physicians in detecting PVCs stems from their long-term correlations with dangerous heart conditions. In other cases their potential as a precursor to serious cardiac events may make their detection a useful early warning mechanism. In many of these applications, the long-term nature of the monitoring required and the infrequency of PVCs make manual observation for PVCs impractical. Existing methods of automated PVC detection suffer from drawbacks such as the need to use difficult to extract morphological features, domain-specific features, or large numbers of estimated parameters. In particular, systems using large numbers of trained parameters have the potential to require large amounts of training data and computation and may have issues generalizing due to their potential to overfit. To address some of these drawbacks, we developed a novel PVC detection algorithm based around a convolutional autoencoder to address these weaknesses and validated our method using the MIT-BIH arrhythmia database.

Discordant Alternans as a Mechanism for Initiation of Ventricular Fibrillation In Vitro

Background Ventricular tachyarrhythmias are often preceded by short sequences of premature ventricular complexes. In a previous study, a restitution-based computational model predicted which sequences of stimulated premature complexes were most likely to induce ventricular fibrillation in canines in vivo. However, the underlying mechanism, based on discordant-alternans dynamics, could not be verified in that study. The current study seeks to elucidate the mechanism by determining whether the spatiotemporal evolution of action potentials and initiation of ventricular fibrillation in in vitro experiments are consistent with model predictions. Methods and Results Optical mapping voltage signals from canine right-ventricular tissue (n=9) were obtained simultaneously from the entire epicardium and endocardium during and after premature stimulus sequences. Model predictions of action potential propagation along a 1-dimensional cable were developed using action potential duration versus diastolic interval data. The model predicted sign-change patterns in action potential duration and diastolic interval spatial gradients with posterior probabilities of 91.1%, and 82.1%, respectively. The model predicted conduction block with 64% sensitivity and 100% specificity. A generalized estimating equation logistic-regression approach showed that model-prediction effects were significant for both conduction block ( P<1×10-15, coefficient 44.36) and sustained ventricular fibrillation ( P=0.0046, coefficient, 1.63) events. Conclusions The observed sign-change patterns favored discordant alternans, and the model successfully identified sequences of premature stimuli that induced conduction block. This suggests that the relatively simple discordant-alternans-based process that led to block in the model may often be responsible for ventricular fibrillation onset when preceded by premature beats. These observations may aid in developing improved methods for anticipating block and ventricular fibrillation.

Coronary sinus as a site for stable temporary atrial pacing to tide over premature ventricular complex-triggered recurrent ventricular fibrillation in a patient with severe left ventricular dysfunction after coronary bypass surgery

Use of atrial pacing has been known, yet underutilized tool for effective temporary pacing whenever needed early after cardiac surgery. The reasons may be frequent failures of epicardial wires (fixed over atria intra-operative) leading to loss of capture. Endocardial atrial pacing sites for temporary pacing are unstable and hence continuous pacing with acceptable thresholds is impossible. We describe a case of ischemic cardiomyopathy and severe left ventricle systolic dysfunction who required atrial pacing post coronary artery bypass grafting (CABG) surgery for around 48–72 hours starting 4th day post operation when he had multiple episodes of ventricular fibrillation (VF) needing many defibrillation shocks. VF episodes were triggered by premature ventricular complexes (PVC) falling on as R on T. Episodes were refractory to anti-arrhythmic drugs and general anesthesia. These PVC were successfully overdriven by atrial pacing by fluoroscopically placing pacing lead in coronary sinus. This led to complete suppression of PVC induced VF for next 48–72 hours while the antiarrhythmic drugs were continued. Subsequently the patient was discharged in stable state. Atrial pacing, though quite valuable during the post-operative period after cardiac surgery, is underutilized, especially when pacing through surgically placed epicardial wire fails. This report is helpful in drawing attention towards coronary sinus (CS) as an alternate site for achieving stable, temporary atrial pacing during the post-operative period. This site can also be utilized for short term dual chamber pacing if required in post-operative state using transvenous CS site for atrial pacing and intraoperatively placed epicardial wire for ventricular pacing.

Autonomic influences related to frequent ventricular premature beats in patients without structural heart disease

To study the possible role of autonomic influences on the occurrence of frequent premature ventricular beats (VPBs) in subjects without structural heart disease.24-hour Holter ECG recordings (≥1500 VPBs/d, sinus rhythm) of 20 symptomatic patients (9 women, 11 men, mean age 58.9 years) without structural heart disease were used for the study. The circadian distribution pattern of VPBs was studied (paired t test) by dividing the day into 3 periods (16:00-22:00-06:00-16:00), and correlations were analyzed between the absolute (ln transformed) and relative (% of total beats) average hourly numbers of VPBs and the hourly mean values of global and vagal time domain parameters of heart rate variability (Pearson correlation).No significant (P > .3 for every comparison) tendency for circadian distribution of VPBs was found. However, VPBs showed a significant correlation with rMSSD (r = 0.51 and P = .02 for the relative number), which became even stronger if VPBs were > 8000/d (r = 0.65 and P = .04 for both numbers).The significant correlation between the number of VPBs and a vagally mediated parameter underlines the triggering/permitting effect of parasympathetic tone on ventricular ectopy. This fact suggests that initiation of beta-blocker therapy could not be recommended routinely in these patients.

Localization of Origins of Premature Ventricular Contraction by Means of Convolutional Neural Network From 12-Lead ECG

OBJECTIVE

This paper proposes a novel method to localize origins of premature ventricular contractions (PVCs) from 12-lead electrocardiography (ECG) using convolutional neural network (CNN) and a realistic computer heart model.

METHODS

The proposed method consists of two CNNs (Segment CNN and Epi-Endo CNN) to classify among ventricular sources from 25 segments and from epicardium (Epi) or endocardium (Endo). The inputs are the full time courses and the first half of QRS complexes of 12-lead ECG, respectively. After registering the ventricle computer model with an individual patient's heart, the training datasets were generated by multiplying ventricular current dipoles derived from single pacing at various locations with patient-specific lead field. The origins of PVC are localized by calculating the weighted center of gravity of classification returned by the CNNs. A number of computer simulations were conducted to evaluate the proposed method under a variety of noise levels and heart registration errors. Furthermore, the proposed method was evaluated on 90 PVC beats from nine human patients with PVCs and compared against ablation outcome in the same patients.

RESULTS

The computer simulation evaluation returned relatively high accuracies for Segment CNN (∼78%) and Epi-Endo CNN (∼90%). Clinical testing in nine PVC patients resulted an averaged localization error of 11 mm.

CONCLUSION

Our simulation and clinical evaluation results demonstrate the capability and merits of the proposed CNN-based method for localization of PVC.

SIGNIFICANCE

This paper suggests a new approach for cardiac source localization of origin of arrhythmias using only the 12-lead ECG by means of CNN, and may have important applications for future real-time monitoring and localizing origins of cardiac arrhythmias guiding ablation treatment.

Activation recovery interval imaging of premature ventricular contraction

Dispersion of ventricular repolarization due to abnormal activation contributes to the susceptibility to cardiac arrhythmias. However, the global pattern of repolarization is difficult to assess clinically. Activation recovery interval (ARI) has been used to understand the properties of ventricular repolarization. In this study, we developed an ARI imaging technique to noninvasively reconstruct three-dimensional (3D) ARI maps in 10 premature ventricular contraction (PVC) patients and evaluated the results with the endocardial ARI maps recorded by a clinical navigation system (CARTO). From the analysis results of a total of 100 PVC beats in 10 patients, the average correlation coefficient is 0.86±0.05 and the average relative error is 0.06±0.03. The average localization error is 4.5±2.3 mm between the longest ARI sites in 3D ARI maps and those in CARTO endocardial ARI maps. The present results suggest that ARI imaging could serve as an alternative of evaluating global pattern of ventricular repolarization noninvasively and could assist in the future investigation of the relationship between global repolarization dispersion and the susceptibility to cardiac arrhythmias.

Is There any Relationship Between Myocardial Repolarization Parameters and the Frequency of Ventricular Premature Contractions?

BACKGROUND

Ventricular premature contractions (VPCs) may trigger lethal ventricular arrhythmias in patients with structural heart disease. However, this role of VPCs in healthy people remains controversial once that not enough clinical trials are available. Recently, some myocardial repolarization markers, such as Tp-e interval, Tp-e/QT, and Tp-e/QTc ratios, have been reported to be useful for predicting lethal ventricular arrhythmias in various clinical disorders without structural heart disease.

OBJECTIVE

In this study, we aimed to investigate the relation between VPC frequent and myocardial repolarization markers in individuals without structural heart disease.

METHODS

This study included 100 patients who had complaints of dizziness and palpitations. Twelve-lead electrocardiography and 24-hour ambulatory Holter recordings were obtained from all patients. VPC burden was calculated as the total number of VPCs divided by the number of all QRS complexes in the total recording time. P-values < 0.05 were considered significant.

RESULTS

Tp-e interval and Tp-e/QTc ratio were significantly higher in patients with higher VPC burden than in patients with lower VPC burden, and a positive correlation was found between these markers and VPC burden. Tp-e (β = 1.318, p = 0.043) and Tp-e/QTc (β = -405.136, p = 0.024) in the lead V5 were identified as independent predictors of increased VPC burden.

CONCLUSIONS

Tp-e interval and Tp-e/QTc ratio increased in patients with high VPC number. Our study showed that VPCs may have a negative effect on myocardial repolarization. This interaction may lead to an increased risk of malignant arrhythmias.

An electrocardiographic diagnostic model for differentiating left from right ventricular outflow tract tachycardia origin

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×(V2S/V3R), 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.

The inhibitory effect of rosmarinic acid on overexpression of NCX1 and stretch- induced arrhythmias after acute myocardial infarction in rats

The incidence of arrhythmias is the main cause of high mortality after myocardial infarction (AMI). The aim of the present study was to determine whether the rosmarinic acid (RA) could reduce the stretch-induced arrhythmias (SIAs) related to overexpression of NCX1 after AMI. Adult male Sprague-Dawley rats were randomly allocated into six groups: Sham, MI (100 mg/kg of isoproterenol (Iso), subcutaneously, on two consecutive days), RA (30 mg/kg, orally, 14 days), and RA (10, 15 and 30 mg/kg, 14 days) + I. MI induction was performed on the 13th and 14th days of the study period. Forty-eight hours after the first injection of Iso, the parameters of hypertrophy, plasma levels of malondialdehyde (MDA) and lipid profile were evaluated. Using Langendorff apparatus, the isolated hearts were transiently stretched for 5 s with three different end-diastolic volumes (ΔV1to3 = 0.05, 0.1 and 0.2 mL). Cardiac function parameters were measured for 30 s, and ventricular arrhythmias were recorded for 3 min after each stretch. Finally, the levels of cardiac troponin-I and NCX1 mRNA expression were examined. The rats of MI group showed a significant increase in hypertrophy index, MDA, triglyceride and cholesterol (P < 0.001). Additionally, a marked impairment in cardiac parameters, an increase in the rates of SIAs and NCX1 expression, and a decrease in troponin-I (P < 0.001) were observed. RA at three doses especially 15 mg/kg strongly improved almost all the mentioned factors (P < 0.001). Our results confirm that RA pretreatment could prevent hypertrophia, arrhythmia and cardiac dysfunction following AMI which is associated with inhibition of lipid peroxidation and overexpression of NCX1.

Mode of initiation and clinical significance of malignant rapid ventricular arrhythmias: An observational study

The purpose of this study was to explore the modes of initiation and clinical significance of malignant rapid ventricular arrhythmias (MRVAs).The surface 12-lead electrocardiogram (ECG) or sustained electrocardiomonitor graph was analyzed in 79 patients. All patients had at least 1 MRVA after being admitted to the hospital.According to the length of coupling interval of the initial premature ventricular contraction of MRVA, the modes of initiation of MRVA were divided into the following types: those initiated by premature ventricular contraction with short coupling intervals in patients with normal Q-T interval, and for which short-long-short sequences before MRVA precipitation were not observed; those initiated following short-long-short sequences, which were divided into 2 types according to the length of Q-T interval: a normal Q-T interval and a long Q-T interval. On the basis of the different modes of onset, treatments of MRVA were different.MRVAs have different modes of onset depending on the patients' underlying condition. Prompt recognition of the mode of onset is necessary to facilitate appropriate management. These findings could have important pathophysiologic and clinical implications.

Ventricular arrhythmia as an initial sign in acute Kawasaki disease: A case report

RATIONALE

Coronary artery lesion is the most prominent cardiac manifestation in Kawasaki disease. However, few cases of life-threatening cardiac arrhythmia were reported in the acute phase of Kawasaki disease.

PATIENT CONCERNS

A 1-year-old girl presented in the hospital with ventricular premature beats and ventricular tachycardia after 2 days of fever.

DIAGNOSIS

On the fifth day of fever, the diagnosis of Kawasaki disease was achieved.

INTERVENTIONS

Immunoglobulin was administered.

OUTCOME

The temperature became normal and ventricular arrhythmia disappeared.

LESSONS

This case suggests that Kawasaki disease has various clinical manifestations besides typical features, and it can cause life-threatening cardiac arrhythmia in the acute phase with normal coronary artery and normal cardiac function.

Frequency of Electrocardiographic Abnormalities in Patients With Psoriasis

Psoriasis is a chronic inflammatory disease associated with cardiovascular disease, for example, myocardial infarction, stroke, cardiovascular death, and arrhythmias. The resting electrocardiogram may carry prognostic information, but limited evidence is available of electrocardiographic findings in subjects with psoriasis. The electrocardiographic results were compared between 1,131 subjects with self-reported psoriasis and 18,397 controls participating in the Danish General Suburban Population Study (GESUS). The mean heart rate was marginally increased in patients with psoriasis (66 ± 11 vs 65 ± 11 beats/min, p = 0.007), but not after adjustment for smoking and body mass index. All other examined electrocardiographic variables, including QT interval corrected for heart rate with the Fridericia formula, PR interval, QRS duration, R axis, P-wave duration in lead V1, P-terminal force, J point elevation in lead V1, electrocardiographic criteria for left ventricular hypertrophy, electrocardiographic signs of previous myocardial infarction, and premature ventricular or supraventricular complexes, respectively, were comparable between the 2 groups. In conclusion, psoriasis was associated with a marginal increase in resting heart rate, which was driven by smoking and increased body mass index. All other examined electrocardiographic variables were similar between the 2 groups. The results suggest that psoriasis per se is not associated with significant abnormalities of the electrocardiogram.

Post-Ventricular Premature Contraction Phase Correction Improves the Predictive Value of Average T-Wave Alternans in Ambulatory ECG Recordings

OBJECTIVE

We proposed and evaluated a method for correcting possible phase shifts provoked by the presence of ventricular premature contractions (VPCs) for a better assessment of T-wave alternans (TWA).  Methods: First, we synthesized ECG signals with artificial TWA in the presence of different noise sources. Then, we assessed the prognostic value for sudden cardiac death (SCD) of the long-term average of TWA amplitude (the index of average alternans, ) in ambulatory ECG signals from congestive heart failure (CHF) and evaluated whether it is sensitive to the presence of VPCs.

RESULTS

The inclusion of the phase correction after VPC in the processing always improved estimation accuracy of the under different noisy conditions and regardless of the number of the VPCs included in the sequence. It also presented a positive impact on the prognostic value of with increased hazard ratios (from 17% to 29%, depending of the scenario) in comparison to the noninclusion of this step.

CONCLUSION

The proposed methodology for estimation, which corrects for the possible phase reversal on TWA after the presence of VPCs, represents a robust TWA estimation approach with a significant impact on the prognostic value of for SCD stratification in CHF patients.

SIGNIFICANCE

An accurate TWA estimation has a potential direct clinical impact on noninvasive SCD stratification, allowing better identification of patients at higher risk and helping clinicians in adopting the most appropriate therapeutic strategy.

Impact of sedation vs. general anaesthesia on percutaneous epicardial access safety and procedural outcomes

Aims

Patient movement while under moderate/deep sedation may complicate percutaneous epicardial access (EpiAcc), mapping and ablation. We sought to compare procedural outcomes in patients undergoing EpiAcc under sedation vs. general anaesthesia (GA) for ablation.

Methods and results

Patients undergoing EpiAcc between January 2004 and July 2014 were included. Safety, procedural, and clinical outcomes were compared between patients undergoing EpiAcc under sedation or GA for ventricular tachycardia or premature ventricular complex ablation. Between January 2004 and July 2014, 170 patients underwent EpiAcc (mean age, 53.2 ± 15.8 years; average ejection fraction, 44.3 ± 15.3%). The majority (122 [72%] patients) were male. GA was used in 69 (40.6%). There was no difference in route of access (more often anterior, 53.0%) or the rate of successful access (96% overall) between groups. Similarly, the site of ablation (endocardial vs. epicardial vs. combined endocardial/epicardial) was similar between groups. Complications were equally seen between groups-the most frequent event/complication was pericardial effusion, occurring in 10.6% of patients. Finally, procedural and clinical success rates between GA and sedation groups were comparable (93 vs. 91% and 44 vs. 51%, respectively, P > 0.05).

Conclusions

Choice of anaesthesia for EpiAcc does not appear to significantly affect safety and procedural or clinical outcomes. For patients in whom anaesthesia may pose increased risk, it is reasonable to obtain epicardial access under sedation.

A correlative study of myocardial infarction scar characteristics by DE-MR and the Lown's classification of ventricular premature beats

OBJECTIVE

Correlation between myocardial infarction (MI) scar by cardiac magnetic resonance and the Lown's classification of ventricular premature beats (VPBs) is poorly understood. This study aims to investigate the correlation between the MI scar characteristics by delayed-enhancement magnetic resonance imaging (DE-MRI) and the Lown's classification of VPBs.

METHODS

Sixty-five patients, in the convalescence stage and consolidation phase of MI, were included in this retrospective study. All patient were divided into VPBs group (n = 39) and non-VPBs group (n = 26 patients) according to the clinical diagnostic criteria of Universal Definition of MI scar. VPBs patients were assigned to Lown's I-II group and Lown's III-IV subgroup in accordance with the Lown classification criteria. Cardiac function parameters and MI scar characteristics were detected by cardiac magnetic resonance (CMR) and DE-MRI, respectively.

RESULTS

Lown's classification was negatively correlated with left ventricular ejection fraction (LVEF), peak ejection rate (PER) and peak filling rate (PFR) (-0.724, -0.628, -0.559), and positively correlated with MI area, MI integral, MI segments number and left ventricular end systolic volume (LVESV) (0.673, 0.655, 0.586, and 0.514), respectively.CONCLUSIONSThe study indicated that MI area and MI integral were strongly associated with Lown's classification.

R-Wave Peak Time at Lead II in Adults With Ventricular Premature Beats, Bundle Branch Block and Left Anterior Fascicular Block

BACKGROUND

Recently, the R-wave peak time (RWPT) at lead II was reported to be a helpful and simple tool for differentiating wide QRS complex tachycardias with a RWPT ≥ 50ms for ventricular tachycardia diagnosis. Our previous study showed that the duration of RWPT at lead II in adults was ≈29ms. However, the effects of ventricular premature beats (VPBs), bundle branch block (BBB) or left anterior fascicular block (LAFB) on RWPT at lead II remain unknown.

METHODS

The study was conducted in the First Affiliated Hospital of Shantou University Medical College in Southern China. Adults with VPBs, BBB or LAFB were included. RWPT at lead II was determined.

RESULTS

Compared with the control groups, the right BBB, LAFB, RWPT were longer in groups with left BBB and VPBs. Compared with the group with left BBB, the group with VPBs had a significantly longer RWPT at lead II (54.20 ± 18.52 versus 84.76 ± 16.38ms, P < 0.01).

CONCLUSION

Our study showed that there is a significant difference in the RWPT at lead II between groups with left BBB, ventricular premature beat, right BBB and LAFB. A RWPT of 50ms may be optimal to differentiate between ventricular tachycardia and supraventricular tachycardia with right left BBB and LAFB, but not with left BBB.

Catheter ablation of premature ventricular contractions originating from aortic sinus cusps in a patient with dextrocardia and situs solitus: A case report

BACKGROUND

Premature ventricular contractions (PVCs) originating from aortic sinus cusps is not infrequent and can be eliminated effectively by radiofrequency ablation with rare complications. However, after a review of the medical literature, and to our knowledge, this is the first case of successful idiopathic aortic sinus cusps-PVC-ablation using a 3-dimensional (3D) mapping system in an adult with dextrocardia.

METHODS

A 62-year-old male with dextrocardia and situs inversus underwent catheter ablation of frequent PVCs. The electrocardiograms (ECG) were recorded by placement of the electrodes in reversed positions. The PVCs exhibited left bundle branch block and inferior axis QRS morphology with transition at leads V2-V3. The activation mapping indicated the earliest site of ventricular activation between the left and right aortic sinus cusps, highlighting that catheter ablation was successful at this point.

RESULTS

The catheter ablation was successful between the left and right aortic sinus cusps, and the PVCs were not detected for the subsequent 30 min following the procedure as well as for the rest of the hospital stay.

CONCLUSION

Combined with ECG electrodes in reversed positions and 3D electroanatomical mapping system, catheter ablation of PVCs originating from aortic sinus cusps in patients with dextrocardia can be safely and effectively performed.