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Background: Alteration in ventricular repolarization has been reported in patients with spinal cord injuries (SCIs). However, its clinical impact remains unclear., Objective: The purpose of this study was to investigate the correlation between SCIs and ventricular repolarization and the associated clinical impact., Methods: One hundred forty-four patients with an SCI were retrospectively reviewed and were divided into two groups (SCI level ≤ T6, n = 110; SCI level >T6, n = 34). The electrocardiograms were reviewed during acute phase (at emergency room) and chronic phase (>1 year)., Results: There were no differences in the underlying diseases or in ASIA score between the two groups, except there were more patients with tetraplegia among those with an SCI level ≤ T6. For the electrophysiological parameters from the electrocardiograms, the patients with an SCI level ≤ T6 had longer QTc and PR interval than those with an SCI level >T6 during acute phase. In the chronic phase, there were no differences in the electrophysiological parameters between the two groups. Only in patients with an SCI level ≤ T6 did a Kaplan-Meier analysis show that QTc prolongation could predict 30-day mortality after the acute injury. After multivariate Cox regression analysis, only tetraplegia and QTc prolongation were independent predictors of 30-day mortality (odds ratios 7.85 and 34.62, respectively). In patients with an SCI level ≤ T6, the QTc intervals were shorter in the chronic phase than those during the acute phase., Conclusion: QTc interval was associated with the level of acute SCI and predicted the 30-day mortality., (Copyright © 2011 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: The noncontact mapping (NCM) system possesses the merit of global endocardial recording for unipolar and activation mapping., Objective: We aimed to evaluate the unipolar electrogram characteristics and activation pattern over the bipolar complex fractionated atrial electrogram (CFAE) sites during atrial fibrillation (AF)., Methods: Twenty patients (age 55 +/- 11 years old, 15 males) who underwent NCM and ablation of AF (paroxysmal/persistent = 13/7) were included. Both contact bipolar (32-300 Hz) and NCM virtual unipolar electrograms (0.5-300 Hz) were simultaneously recorded along with the activation pattern (total 223 sites, 11 +/- 4 sites/patient). A CFAE was defined as a mean bipolar cycle length of

Aims: Fibrillatory waves observed in the surface electrograms may be a direct reflection of the electrophysiologic mechanism of the atrial fibrillation (AF). This study compared the fibrillatory waves in the surface ECG and the individual intracardiac mapping sites in different types of paroxysmal AF., Methods and Results: Thirty patients with paroxysmal AF originating from the pulmonary veins (PVs) or superior vena cava (SVC) were enrolled. Frequency analysis was performed on the intracardiac electrograms recorded from various mapping sites in both atria sequentially with simultaneous surface electrogram recordings. The SVC-AF patients had a trend toward a higher DF in ECG lead V1 when compared with the PV-AF patients (7.35 +/- 2.09 vs. 5.89 +/- 0.79 Hz, P = 0.018). The mean dominant frequency (DF) of the LA mapping sites in the PV-AF patients was higher than that in the SVC-AF patients (7.06 +/- 0.66 vs. 6.13 +/- 0.96 Hz, P = 0.009), whereas the mean DF of the RA mapping sites was similar between the two groups (5.84 +/- 0.80 vs. 6.26 +/- 1.11 Hz, P = NS). The intra-class correlation coefficient (ICC) between the mean DF of the RA sites and V1 was higher (r = 0.21, P = 0.02) when compared with the mean DF of the LA sites (r = -0.007, P > 0.05). Furthermore, the maximal ICC was observed in the anterolateral RA free wall (r = 0.84, P < 0.001) and not the other anatomic sites of the RA and LA., Conclusion: The fibrillatory activity observed in ECG lead V1 correlated primarily with the activity of the anterolateral RA free wall and thus may be useful for detecting the AF source if it is close to that area.

Introduction: Paroxysmal supraventricular tachycardia (PSVT) is often associated with paroxysmal atrial fibrillation (AF). However, the relationship between PSVT and AF is still unclear. The aim of this study was to investigate the clinical and electrophysiological characteristics in patients with PSVT and AF, and to demonstrate the origin of the AF before the radiofrequency (RF) ablation of AF., Methods and Results: Four hundred and two consecutive patients with paroxysmal AF (338 had a pure PV foci and 64 had a non-PV foci) that underwent RF ablation were included. Twenty-one patients (10 females; mean age 47 +/- 18 years) with both PSVT and AF were divided into two groups. Group 1 consisted of 14 patients with inducible atrioventricular nodal reentrant tachycardia (AVNRT) and AF. Group 2 consisted of seven patients with Wolff-Parkinson-White (WPW) syndrome and AF. Patients with non-PV foci of AF had a higher incidence of AVNRT than those with PV foci (11% vs. 2%, P = 0.003). Patients with AF and atypical AVNRT had a higher incidence of AF ectopy from the superior vena cava (SVC) than those with AF and typical AVNRT (86% vs. 14%, P = 0.03). Group 1 patients had smaller left atrial (LA) diameter (36 +/- 3 vs. 41 +/- 3 mm, P = 0.004) and higher incidence of an SVC origin of AF (50% vs. 0%, P = 0.047) than did those in Group 2., Conclusion: The SVC AF has a close relationship with AVNRT. The effect of atrial vulnerability and remodeling may differ between AVNRT and WPW syndrome.

Background: Temporal variation in complex fractionated atrial electrograms (CFAEs) exists during atrial fibrillation (AF)., Objective: This study sought to quantify the variation in CFAEs using a fractionation interval (FI) algorithm and to define the shortest optimal recording duration required to consistently characterize the magnitude of the fractionation., Methods: Twenty-seven patients undergoing AF mapping in the left atrium were studied. The FI and frequency analysis were performed at each mapped site for recording durations of 1 to 8 seconds. The magnitude of the fractionation was quantified by the FI algorithm, which calculated the mean interval between multiple, discrete deflections during AF. The results from each duration were statistically compared with the maximal-duration recording, as a standard. The FI values were compared with the dominant frequency values obtained from the associated frequency spectra., Results: The FIs obtained from recording durations between 5 and 8 seconds had a smaller variation in the FI (P < .05) and, for those sites with a FI < 50 ms, the fractionation was typically continuous. The fast-Fourier Transform spectra obtained from the CFAE sites with recording durations of >5 seconds harbored higher dominant frequency values than those with shorter recording durations (8.1 +/- 2.5 Hz vs. 6.8 +/- 0.98 Hz, P < .05). The CFAE sites with continuous fractionation were located within the pulmonary veins and their ostia in 77% of patients with paroxysmal AF, and in only 29% of patients with nonparoxysmal AF (P < .05)., Conclusion: The assessment of fractionated electrograms requires a recording duration of > or =5 seconds at each site to obtain a consistent fractionation. Sites with the shortest FIs consistently identified sites with the fastest electrogram activity throughout the entire left atrium and pulmonary veins.

Background: The optimal recording technique of the electrogram voltage for detecting abnormal atrial tissue remains unclear. The aim of this study was to compare the impact of various recording techniques on the electrogram voltage after the delivery of ablation therapy in the human right atrium (RA)., Material and Methods: Noncontact mapping was performed in 27 patients with typical atrial flutter (mean age = 63 +/- 16, males = 20). Noncontact unipolar and bipolar electrograms were obtained before and after cavotricuspid isthmus (CTI) linear ablation. All unipolar electrograms were acquired with both wide-band filtering (0.5-300 Hz) and narrow-band filtering (32-300 Hz). The unipolar voltage measurements included both the peak-to-peak voltage and peak-negative voltage (PNV) for both filter settings., Results: A comparison of the electrogram voltage along the ablation line before and after the ablation demonstrated a greater reduction in the unipolar PNV with wide-band filtering (70 +/- 24%) than in any of the other recording modalities (P = 0.03). It was the most sensitive and specific recording technique to predict conduction block (cut-off Value 0.35 mV; sensitivity = 94.4% and specificity = 80%). A comparison of the electrogram voltage between the ablated atrial myocardium and nearby nonablated myocardium showed that the unipolar PNV with the wide-band filtering remained the most sensitive method to detect the acute ablative tissue injury, whereas the peak-to-peak bipolar voltage was the most specific method., Conclusion: The noncontact unipolar electrogram using the PNV with wide-band filter settings (0.5-300 Hz) provided the most sensitive recording technique for detecting acute ablative tissue injury.

Objectives: This study was performed to differentiate upper loop re-entry (ULR) from reverse typical atrial flutter (AFL)., Background: Right atrial ULR and reverse typical AFL have different mechanisms and ablation strategies, but similar electrocardiographic characteristics., Methods: This study included 26 patients with reverse typical AFL and 20 patients with ULR. The noncontact mapping system (EnSite-3000, Endocardial Solutions, St. Paul, Minnesota) was used to confirm diagnosis and guide successful radiofrequency ablation. Flutter wave polarity and amplitude in the 12-lead surface electrocardiogram were determined by two independent electrophysiologists., Results: The flutter wave polarity in leads I and aVL was significantly different between the reverse typical AFL and ULR groups (p < or = 0.001). Voltage measurement revealed significant differences between reverse typical AFL and ULR in leads I, II, aVR, aVF, V1, and V2 (p < 0.001). A new diagnostic algorithm based on negative or isoelectric/flat flutter wave polarity and amplitude < or =0.07 mV in lead I was useful for diagnosis of ULR, with an accuracy of 90% to 97%, a sensitivity of 82% to 100%, and a specificity of 95%., Conclusions: Polarity and voltage measurement of flutter wave in lead I can differentiate reverse typical AFL from ULR.

Atrioventricular reciprocating tachycardia (AVRT) is known to be the most common supraventricular tachycardias in childhood. Because AF with rapid ventricular response may degenerate to ventricular fibrillation through conduction of accessory pathways (APs), it can be potentially life-threatening in some pediatric patients with WPW syndrome. However, information about WPW syndrome children associated with AF is limited. The purpose of this study was to investigate the specific electrophysiological characteristics in pediatric patients with WPW syndrome and AF. From July 1992 to February 2002, 51 pediatric patients with manifest WPW syndrome and documented AVRT underwent electrophysiological study and radiofrequency catheter ablation. In these patients, two (4%) were found to have several spontaneous episodes of AF recognized on 12-lead standard ECG or 24-hour Holter monitoring. Eleven (22%) patients had AF induced by rapid atrial pacing during the baseline procedure of electrophysiological study. The children with manifest WPW syndrome were divided into two groups: those with AF (group 1; n = 11) consisted of seven male and four female children (mean age 15 +/- 3 years, range 10-18), and those without AF (group 2; n = 40) consisted of 22 boys and 18 girls (mean age 16 +/- 3 years, range 7-18). The study excluded a patient who had Ebstein's anomaly associated with moderate tricuspid regurgitation and right atrial enlargement. The onset and duration of symptoms were not significantly different between the two groups. Comparing the electrophysiological characteristics, the atrial effective refractory period (ERP) was shorter in WPW syndrome children with AF (170 +/- 36 vs 190 +/- 38 ms, P = 0.041). This study demonstrated that the pediatric WPW syndrome patients with AF had different electrophysiological characteristics from those without AF.

Introduction: The superior vena cava (SVC) and right superior pulmonary vein (RSPV) are anatomically close structures. Using 12-lead ECG may facilitate identification of ectopic foci from SVC or RSPV. The aim of this study was to assess whether P wave polarity on surface ECG is helpful in distinguishing an arrhythmogenic focus of paroxysmal atrial fibrillation (AF) from SVC or RSPV., Methods and Results: Thirty-four patients with paroxysmal AF from the SVC (group I: 17 patients, 10 men and 7 women; mean age 57 +/- 12 years) or RSPV (group II: 17 patients, 15 men and 2 women, mean age 62 +/- 14 years) underwent electrophysiologic study and radiofrequency (RF) catheter ablation. All of the AF foci were confirmed by successful ablation. P wave polarities on surface ECG inferior leads were positive during sinus rhythm and ectopic beats in both groups. Leads I, aVR, aVL, and V1 were further analyzed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in predicting an arrhythmogenic focus of AF from SVC or RSPV were provided. P wave polarity in lead aVR was negative in all 34 patients. P wave polarity in lead V1 was positive in 47.1% of SVC ectopy but positive in all RSPV ectopy. The combination of a biphasic or isoelectric P wave polarity in lead V1 or a biphasic P wave polarity in lead aVL had a sensitivity of 71%, specificity of 82%, PPV of 80%, and NPV of 74% in predicting an arrhythmogenic focus of AF from SVC., Conclusion: P wave polarity in leads V1 and aVL may predict an arrhythmogenic focus of AF from SVC or RSPV.

Monophasic action potential-like electrocardiogram simulating acute myocardial infarction has been reported in patients with hyperkalemia. We report two cases presenting marked diffuse RS-T elevation resembling monophasic action potential. They had abnormal electrolyte levels, including hyperkalemia and hypocalcemia in case 1 and hypokalemia and hypocalcemia in case 2. The ECG abnormality returned to baseline after correction of potassium and calcium. We conclude that monophasic action potential-like electrocardiogram is caused by electrolyte disturbance other than acute myocardial infarction.

The average rate of fibrillatory activity may reflect the global activation pattern of AF. Electrical cardioversion is the most effective method of converting chronic AF to sinus rhythm. The aim of this study was to investigate the relation between the minimal defibrillation energy requirement and the dominant frequency of chronic AF. Twenty-nine patients with chronic AF (mean duration 57.9 +/- 7.7 months) underwent external electrical cardioversion. Before cardioversion, the frequency content of the 60-second AF in ECG lead V1 was quantified using digital signal processing. After band-pass filtering, QRST complexes were cancelled using a recursive lease squares algorithm. The resulting fibrillatory baseline signal was subjected to fast Fourier transform and was displayed as a power spectrum. The dominant AF frequency was found to range from 4.9 to 8.7 Hz (mean 6.7 +/- 0.9 Hz). Twenty-six patients had successful conversion of AF to sinus rhythm without immediate recurrence. There was a positive correlation between the minimal defibrillation energy and the dominant frequency of chronic AF (rho = 0.414, P = 0.035). Thus, power spectral analysis of AF using the surface ECG is feasible and may be useful in predicting the minimal shock energy required for successful cardioversion of chronic AF.

Macroreentrant and Focal Atrial Tachycardias. Background: Atrial tachycardias (ATs) are commonly observed following catheter ablation of atrial fibrillation (AF). The aim of this study was to identify ECG characteristics that differentiate focal from macroreentrant ATs after circumferential pulmonary vein isolation (CPVI). Methods and Results: One hundred and twenty ATs that occurred after CPVI were mapped using a 3-dimensional mapping system in 87 patients with AF. Further ablation was performed to eliminate the ATs. The surface ECGs of 68 ATs in 41 consecutive patients (Group 1) were analyzed retrospectively to create diagnostic algorithms. The algorithms were tested in the second 46 consecutive patients (Group 2). Patients with macroreentrant AT had lower left atrial (LA) voltage than those with focal AT (1.3 ± 0.3 vs 1.5 ± 0.2 mV, P = 0.01). Focal AT had a higher incidence of a positive polarity in V6 compared with macroreentrant AT (88% vs 55%, P = 0.03). The positive amplitude of the flutter/P waves in V6 was higher for focal AT than macroreentrant AT. The cycle lengths of the focal ATs were longer than those for macroreentrant AT (296 ± 107 vs 244 ± 25 ms, P < 0.001). Right atrial macroreentrant AT had a higher incidence of a negative polarity in at least 1 precordial lead compared with LA macroreentry. The positive flutter waves in V1 could differentiate roof/mitral isthmus dependent from non-roof/mitral isthmus dependent macroreentry. This algorithm correctly differentiated the focal from macroreentrant ATs with a sensitivity of 94%, specificity of 91%, and predictive accuracy of 92% in Group 2. Conclusion: Different electrophysiological properties may facilitate the differentiation between macroreentrant and focal ATs after CPVI. (J Cardiovasc Electrophysiol, Vol. 22, pp. 748-755, July 2011) [ABSTRACT FROM AUTHOR]

Information about the impact of age on the electrophysiological characteristics of accessory pathways (APs) in patients with Wolff-Parkinson-White (WPW) syndrome remains limited. A total of 1,885 consecutive patients (mean age 43 ± 17 years, male 61.5%) with WPW syndrome who were referred to the tertiary center for an electrophysiological study and radiofrequency catheter ablation were investigated. The patients were divided into 4 groups based on their age (Group 1: <20; Group 2: 20-39; Group 3: 40-59; Group 4: ≧60 years old). With age, more left-sided APs (53.2%, 67.7%, 71.7%, 75.7%, P < 0.001) and a longer duration of the arrhythmia (4.3 ± 2.8 years, 10.1 ± 7.0 years, 12.4 ± 10.9 years, 14.0 ± 12.4 years, P < 0.001) were noted. The incidence of concealed APs (53.5%, 53.0%, 57.8%, 60.9%, P = 0.01), and orthodromic atrioventricular (AV) reentrant tachycardia (92.4%, 94.2%, 96.5%, 96.3%, P = 0.023) increased with age. The tachycardia cycle length, antegrade (275.5 ± 42.2 ms, 286.7 ± 62.7 ms, 302.5 ± 66.5 ms, 315.2 ± 80.2 ms, P < 0.001) and retrograde AP effective refractory periods (APERPs) (254.0 ± 42.5 ms, 263.3 ± 51.8 ms, 274.5 ± 100.5 ms, 292.7 ± 57.0 ms, P < 0.001), atrial ERP, antegrade AV node effective refractory period (AVNERP), and ventricular effective refractory period (VERP) lengthened as the age increased. The incidence of decremental APs, multiple APs, and a catecholamine response were similar. The duration of the catheter ablation, total fluoroscopy time, acute success rate, complication rate, and incidence of a secondary procedure were similar between the different age groups. The electrophysiological characteristics and pattern of the arrhythmic attack associated with the AP changed with age. (J Cardiovasc Electrophysiol, Vol. 22, pp. 274-279, March 2011) [ABSTRACT FROM AUTHOR]

Introduction: The left atrial (LA) substrate plays an important role in the maintenance of atrial fibrillation (AF). However, little is known about the acute effect of circumferential pulmonary vein isolation (CPVI). This study was to investigate the acute change of LA activation, voltage and P wave in surface electrocardiogram (ECG) after CPVI. Methods and Results: Electroanatomic mapping (NavX) was performed in 50 patients with AF (mean age = 54 ± 10 years, 36 males) who underwent only CPVI. The mean peak-to-peak bipolar voltage and total activation time of LA were obtained during sinus rhythm before and immediately after CPVI. The average duration and amplitude of P waves in 12-lead ECG were also analyzed before and after CPVI. Change in the earliest LA breakthrough sites could cause decreased LA total activation time. Downward shift in the breakthrough site was inversely proportional to the proximity of the breakthrough site to the radiofrequency lesions. A shortening of P-wave duration and decrease in voltage after CPVI were observed after CPVI. Patients with recurrent AF had less voltage reduction in the atrial wall 1 cm from the circumferential PV lesions compared with those without recurrent AF (60.1 ± 11.7% vs 74.1 ± 6.6%, P = 0.002). Reduction of voltage ≤64.4% in this area after CPVI is related with recurrent AF. Conclusion: CPVI could result in acute change of LA substrate, involving LA activation and voltage. Less reduction of voltage in the atrial wall adjacent to the circumferential PV lesions after CPVI may be associated to the recurrence of AF. [ABSTRACT FROM AUTHOR]

Characteristics of Midseptal Accessory Pathways. Background:The purpose of the present study was to investigate the electrocardiographic and electrophysiologic characteristics of right midseptal (RMS) and left midseptal (LMS) accessory pathways (APs), and to develop a stepwise algorithm to differentiate RMS from LMS APs.Methods and Results:From May 1989 to February 2004, 1591 patients with AP-mediated tachyarrhythmia underwent RF catheter ablation in this institution, and 38 (2.4%) patients had MS APs. The delta wave and precordial QRS transition during sinus rhythm, retrograde P wave during orthodromic tachycardia, and electrophysiologic characteristic and catheter ablation in 30 patients with RMS APs and 8 patients with LMS APs were analyzed. There was no significant difference in electrophysiologic characteristics and catheter ablation between RMS and LMS APs. The polarity of retrograde P wave during orthodromic tachycardia also showed no statistical difference between patients with RMS and LMS APs. The delta wave polarity was positive in leads I, aVL, and V3 to V6 in patients with RMS and LMS APs. Patients with LMS APs had a higher incidence of biphasic delta wave in lead V1 than patients with RMS APs (80% vs. 15%, P= 0.012). The distributions of precordial QRS transition were different between RMS APs (leads V2; n= 10, V3; n= 7 and V4; n= 3) and LMS APs (leads V1; n= 1 and V2; n= 4) (P= 0.03). The combination of a delta negative wave in lead V1 or precordial QRS transition in lead V3 or V4 had a sensitivity of 90%, specificity of 80%, positive predictive value of 95%, and negative predictive value of 66% in predicting an RMS AP.Conclusions:Delta wave polarity in lead V1 and precordial QRS transition may differentiate RMS and LMS APs.(J Cardiovasc Electrophysiol, Vol. 16, pp. 1-7, March 2005) [ABSTRACT FROM AUTHOR]

Repolarization Changes During SVT. Introduction: Previous literature has documented the association between narrow QRS supraventricular tachycardia (SVT) and pronounced ST-T segment change. The aim of this study was to evaluate repolarization changes during SVT initiation and demonstrate the possible mechanism. Methods and Results: Fifty-one consecutive patients (20 men and 31 women; mean age 46.1 ± 16.4 years) with narrow QRS SVT (32 patients with AV nodal reentrant tachycardia and 19 patients with AV reentrant tachycardia) were included. We retrospectively analyzed the intracardiac recordings and ST-T segment changes on 12-lead surface ECGs during SVT initiation. Twenty-six (51%) patients developed ST segment repolarization changes during SVT initiation. Patients with shorter baseline sinus cycle length, shorter tachycardia cycle length, elevated systolic blood pressure before tachycardia induction, and greater reduction of systolic blood pressure had a higher incidence of repolarization changes. However, multivariate analysis showed that reduction of systolic blood pressure after SVT induction was the only independent predictor of repolarization changes. Furthermore, the maximal degree of ST segment depression during SVT correlated with the reduction of systolic blood pressure (r = 0.75, P < 0.001). Conclusion: Repolarization changes during SVT initiation were caused mainly by concurrent hemodynamic change after SVT initiation with abrupt cycle length shortening. [ABSTRACT FROM AUTHOR]

We report a case with SVC ectopy initiating AF; the origin and breakout point of the sinus node was inside the SVC, and the SVC ectopy was conducted through the same path as the sinus node activation to depolarize the right atrium. Injury to the sinus node happened after successful isolation of SVC. [ABSTRACT FROM AUTHOR]

SVC Rhythm Masquerading as NSR . We report the case of a patient with persistent cardiac rhythm originating from the superior vena cava (3 cm above the vena cava-atrial junction). It was detected by noncontact balloon mapping before induction of tachycardia and confirmed by conventional contact mapping with image studies. Thus, a 12-lead ECG showing normal morphologies of P waves may not indicate that the P waves are of sinus node origin. (J Cardiovasc Electrophysiol, Vol. 15, pp. 950-952, August 2004) [ABSTRACT FROM AUTHOR]

The article presents a medical case of a 51-year-old patient who developed incessant wide QRS tachycardia after pulmonary vein isolation and pacemaker implantation for the treatment of tachycardia-bradycardia syndrome. Five months after the surgery, he presented with palpitations and exertional dyspnea. A 12-lead electrocardiography revealed a wide QRS tachycardia, with a rapid regular ventricular paced rhythm and irregular P waves.

The article comments on the mechanism of pseudosinus rhythm. According to the author the potential mechanisms of the dissociated sinus rhythm were postulated as the origin of the arrhythmogenic foci that were from the superior vena cava (SVC) and right superior pulmonary vein (RSPV), with exit block from both sites, resulting in the dissociated right and left atrial activities. Another is the arrhythmogenic focus originated in the SVC with exit block, and far-field potentials from the SVC were recorded in the RSPV. Recent evidence indicates that focal electric firing originating from the SVC can initiate paroxysmal atrial fibrillation.

Describes a case involving a patient suffering from alternating wide and narrow QRS complex tachycardias. Symptoms exhibited by the patient; Characteristics of tachycardias; Diastolic potential shown by endocardial mapping.

Describes the electrocardiogram of a 25-year-old man with supraventricular tachycardia with intermittent 2:1 atrioventricular conduction. Mechanism behind the spontaneous termination of atrioventricular nodal reentrant tachycardia with 2:1 atrioventricular block.