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Biomedical subjects

Yenn-Jiang Lin

Publications and source records attributed to Yenn-Jiang Lin.

At least 37 records · Page 2Linked to original sources
PubMed2005

A new electrocardiographic algorithm to differentiate upper loop re-entry from reverse typical atrial flutter.

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.

Adult↗
PubMed2005

Effects of right bundle branch block during atrioventricular nodal reentrant tachycardia.

BACKGROUND: The significant role of bundle branch block during atrioventricular nodal reentrant tachycardia (AVNRT) is not clear. The purposes of this study were to study the effects of complete right bundle branch block (RBBB) on electrophysiological parameters during AVNRT and to define the significance of complete RBBB during AVNRT. METHODS AND RESULTS: According to characteristics of electrocardiogram during sinus rhythm and AVNRT, 50 patients who underwent catheter ablation for slow-fast AVNRT were divided into three groups. Group I included 20 patients who had narrow QRS (< or = 110 ms) during sinus rhythm and AVNRT. Group II included 18 patients who had persistent RBBB (< or = 120 ms) during sinus rhythm and AVNRT. Group III included 12 patients who had narrow QRS during sinus rhythm, but they had narrow QRS and transient RBBB during AVNRT. The atrio-His (AH) interval (296+/-60 vs. 288+/-75 ms), His-ventricular (HV) interval (36+/-11 vs. 35+/-11 ms), His-atrial (HA) interval (72+/-24 vs. 71+/-28 ms), VA(HRA) interval (defined as the interval between the onset of ventricular depolarization and the onset of atrial activity of right high atrium; 34+/-24 vs. 37+/-25 ms), VA(CSO) interval (defined as the interval between the onset of ventricular depolarization and the onset of atrial activity of coronary sinus ostium; 13+/-28 vs. 26+/-23 ms) and tachycardia cycle length (TCL; 368+/-67 vs. 359+/-73 ms) during AVNRT were similar between group I and group II (all P > 0.05). In group III, the AH interval (255+/-81 vs. 246+/-83 ms), HV interval (44+/-5 vs. 42+/-11 ms), HA interval (66+/-19 vs. 70+/-15 ms), VA(HRA) interval (27+/-15 vs. 29+/-16 ms), VA(CSO) interval (23+/-25 vs. 21+/-25 ms) and TCL (322+/-76 vs. 316+/-77 ms) were not significantly different between AVNRT with narrow QRS and those with transient RBBB (all P > 0.05). CONCLUSIONS: Persistent RBBB and transient RBBB have no significant effects on the electrophysiological parameters during AVNRT. These findings suggest that RBBB might not influence the conduction of lower common pathway or the circuit of AVNRT.

Adult↗
PubMed2005

Electrocardiographic and electrophysiologic 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.

Adolescent↗
PubMed2005

Characterization of right atrial substrate in patients with supraventricular tachyarrhythmias.

UNLABELLED: Right atrial substrate of supraventricular tachyarrhythmias. BACKGROUND: Voltage mapping has been used to detect diseased myocardium. However, accurate determination of the local atrial voltage at the same site, and simultaneous recordings from multiple mapping sites were limited. The purpose of this study was to investigate the right atrial (RA) substrate properties in patients with supraventricular tachyarrhythmias (SVT). METHODS AND RESULTS: Forty patients (aged 55+/-20 years) undergoing noncontact mapping and ablation of SVT constituted the study population. There were eight patients with atrioventricular node reentrant tachycardia (AVNRT), eight patients with focal atrial tachycardia (AT), 14 patients with atrial flutter (AFL), and 10 patients with atrial fibrillation (AF). The mean peak negative voltage (PNV) was analyzed in virtual unipolar electrograms, which were obtained from 256 equally distributed RA endocardial sites during sinus rhythm (SR), atrial pacing, and tachycardia. The mean PNV of global RA during SR (-1.34+/-0.22 vs. -0.90+/-0.40 vs. -1.00+/-0.36 vs. -0.85+/-0.35 mV, P=0.04), atrial pacing at cycle lengths of 500 ms (-1.30+/-0.29 vs. -0.70+/-0.35 vs. -0.76+/-0.25 vs. -0.64+/-0.26 mV, P=0.02), and 300 ms (-1.54+/-0.47 vs. -0.94+/-0.21 vs. -0.75+/-0.27 vs. -0.57+/-0.22 mV, P<0.01) were significantly greater in patients with AVNRT compared to AT, AFL, and AF. Furthermore, the mean PNV decreased during atrial pacing with shorter pacing cycle length was demonstrated only in patients with AFL and AF. CONCLUSION: Negative unipolar voltage analysis of global RA showed different RA substrate characteristics during various SVT. The substrate property of activation and cycle length-dependent voltage reduction may be related to the development of AFL and AF.

Atrial Fibrillation↗
PubMed2005

Morphology of the thoracic veins and left atrium in paroxysmal atrial fibrillation initiated by superior caval vein ectopy.

INTRODUCTION: The structural changes of the superior caval vein, pulmonary veins, and left atrium in atrial fibrillation initiated by superior caval vein ectopy have not been reported. METHODS AND RESULTS: Nine patients with atrial fibrillation initiated by superior caval vein ectopic beats (male = 5, 54 +/- 10 years) and 15 control (n = 15, male = 10, 52 +/- 8 years) without any cardiac arrhythmias were included in this study. Using gadolinium-enhanced magnetic resonant angiography with three-dimensional reconstruction, the parameters of the superior caval vein morphology (length, various diameters, area, eccentricity, and volume) were measured. The morphological parameters of the four pulmonary veins (diameter, ostial area, and eccentricity) were also measured at the pulmonary vein-left atrial junction in an oblique sagittal section from the multiple-plane reconstruction images. The left atrial diameters and volume were measured. The different morphological parameters were compared between the two groups. The patients with atrial fibrillation initiated by superior caval vein ectopic beats exhibited a more eccentric structure of the second part of the superior caval vein as compared to the control group. All the ectopic beats initiating atrial fibrillation were located in the second part of the superior caval vein. Furthermore, the patients with atrial fibrillation initiated by superior caval vein ectopic beats had a larger superior caval vein volume, left atrial volume, and pulmonary vein size, and more eccentric pulmonary vein ostia than the controls. CONCLUSION: Structural changes of the superior caval vein were demonstrated in the patients with atrial fibrillation initiated by superior caval vein ectopic beats. These findings might explain the arrhythmogenic mechanism of atrial fibrillation initiated by superior caval vein ectopy.

Atrial Fibrillation↗
PubMed2005

Sinus node injury as a complication of superior vena cava isolation.

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.

Atrial Fibrillation↗
PubMed2004

Non-contact mapping to guide radiofrequency ablation of atypical right atrial flutter.

OBJECTIVES: This study was aimed at evaluating the efficacy of non-contact mapping and ablation of non-incisional atypical right atrial (RA) flutters. BACKGROUND: The majority of atypical RA flutters were reported in patients after surgical incision of the RA. METHODS: The study group consisted of 15 patients (61 +/- 13 years, 8 males) with atypical atrial flutter (AFL). The RA activation during AFL was delineated using a non-contact mapping system (EnSite 3000 with Precision Software, Endocardial Solutions, St. Paul, Minnesota). The narrowest part of each reentrant circuit was targeted using radiofrequency energy. RESULTS: In all 15 patients, non-contact mapping showed AFLs confined to the RA with RA activation time accounting for 100% of the cycle length (210 +/- 19 ms). During single-loop re-entry in seven patients, the activation wave front circulated around the central obstacle (CO) in the anterolateral wall with conduction through the channel between the CO and the crista terminalis (CT). During figure-of-eight re-entry in eight patients, simultaneous upper and lower loop re-entry through the conduction gap in the CT was found in four patients, and simultaneous upper loop and free-wall single-loop re-entry was observed in four patients. Radiofrequency ablation of the free-wall channel and/or CT gap was effective in eliminating these AFLs in 13 patients. During a follow-up of 16.8 +/- 3.8 months, two patients had recurrence of left AFL, and one had recurrence of atrial fibrillation. CONCLUSIONS: Atypical RA flutters could arise from single-loop or double-loop figure-of-eight re-entry. Radiofrequency ablation of the free-wall channel and/or the CT gap was effective in eliminating these arrhythmias.

Adult↗
PubMed2004

Characteristics of virtual unipolar electrograms for detecting isthmus block during radiofrequency ablation of typical atrial flutter.

OBJECTIVES: The purpose of this study was to investigate the characteristics of the second component of local virtual unipolar electrograms recorded at the ablation line during coronary sinus (CS) pacing after radiofrequency ablation (RFA) of the cavotricuspid isthmus (CTI) for typical atrial flutter (AFL). BACKGROUND: Radiofrequency ablation of the CTI can produce local double potentials at the ablation line. The second component of unipolar electrograms represents the approaching wavefront in the right atrium opposite the pacing site. We hypothesized that the morphologic characteristics of the second component of double potentials would be useful in detecting complete CTI block. METHODS: Radiofrequency ablation of the CTI was performed in 52 patients (males = 37, females = 15, 62 +/- 12 years) with typical AFL. The noncontact mapping system (Ensite 3000, Endocardial Solutions, St. Paul, Minnesota) was used to guide RFA. Virtual unipolar electrograms along the ablation line during CS pacing after RFA were analyzed. Complete or incomplete CTI block was confirmed by the activation sequence on the halo catheter and noncontact mapping. RESULTS: Three groups were classified after ablation. Group I (n = 37) had complete bidirectional CTI block. During CS pacing, the second component of unipolar electrograms showed an R or Rs pattern. Group II (n = 12) had incomplete CTI block. The second component of unipolar electrograms showed an rS pattern. Group III (n = 3) had complete CTI block with transcristal conduction. The second component of unipolar electrograms showed an rSR pattern. CONCLUSIONS: A predominant R-wave pattern in the second component of unipolar double potentials at the ablation line indicates complete CTI block, even in the presence of transcristal conduction.

Action Potentials↗
PubMed2004

Functional characterization of the crista terminalis in patients with atrial flutter: implications for radiofrequency ablation.

OBJECTIVES: The aim of the study was to investigate the conduction properties and anisotropy of the crista terminalis (CT) in patients with atrial flutter (AFL) using non-contact mapping. BACKGROUND: The CT is a posterior barrier during typical AFL. However, the CT has transverse conduction capabilities in patients with upper loop re-entry (ULR). METHODS: Twenty-two patients (16 males, 63 +/- 15 years) with typical AFL and ULR were included. Non-contact mapping of the right atrium during AFL and pacing from coronary sinus (CS) and low anterolateral right atrium (LARA) was performed to evaluate transverse conduction across the CT. During ULR, the longitudinal (CV(L)) and transverse (CV(T)) conduction velocity along and across the CT were measured. The width of the CT conduction gap was evaluated to guide radiofrequency ablation (RFA). RESULTS: No transverse CT gap conduction was found during typical AFL. Transverse CT gap conduction was found in three patients during CS pacing and in three patients during LARA pacing. During ULR, CV(L) was greater than CV(T) (1.28 +/- 0.43 vs. 0.73 +/- 0.30 m/s, p < 0.001). The CV(L)/CV(T) ratio was 1.95 +/- 0.77, which was inversely related to the CT gap width (15.7 +/- 6.8 mm) (p < 0.001). The RFA of the CT gap was successful in 18 patients. Four patients had recurrence of arrhythmias during the follow-up of 11 +/- 3 months. CONCLUSIONS: Most of the CT conduction gaps were functional and only appeared during ULR. The width of the CT gap was inversely related to the anisotropic ratio of the CT. The RFA of the CT gap was effective in eliminating ULR.

Aged↗
PubMed2004

Comparison of hemostatic activation created by right- and left-heart radiofrequency catheter ablation.

BACKGROUND: Thromboembolic complications commonly occur in radiofrequency (RF) ablation procedures (0.6-1.3% of cases). Comparison of hemostatic activation between left and right RF ablation is limited. HYPOTHESIS: The purpose of this study was to evaluate platelet and hemostatic activation before, immediately after, and 48 h following left and right myocardial RF ablation procedures. METHODS: The subjects were two groups of patients who underwent right-heart (24 patients) and left-heart (20 patients) RF ablation. Blood samples taken before, immediately after, and 48 h after the procedure were tested for changes in platelet and hemostatic activation. RESULTS: No indication of clinically symptomatic thromboembolism and no major differences in baseline characteristics and procedure were apparent in either group, except for a higher temperature mode setting (p < 0.001) in the left-heart group. The hemostatic evaluation levels increased significantly by the end of the procedure in both groups and the platelet activation level remained elevated for 48 h after the procedure. The platelet activation level increased insignificantly at the end and 48 h after the procedure. Of the other changes in levels of platelet and hemostatic activation, only an increase in one of the hemostatic levels in the right-heart group at 48 h after procedure was significant (p = 0.01). CONCLUSIONS: Our findings suggest that similar hemostatic activation occurred during and immediately after RF ablation in both groups. Sustained elevation of the hemostatic marker after the ablation procedure in the right-heart group was observed as of significant therapeutic and prognostic implications.

Adult↗
PubMed2004

Mechanism of repolarization change during initiation of supraventricular tachycardia.

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.

Adult↗
PubMed2004

Mechanism of adenosine-induced termination of focal atrial tachycardia.

INTRODUCTION: Adenosine can terminate most focal atrial tachycardias (ATs). However, information about the termination mechanism is limited. This study investigated the effects and mechanism of adenosine on terminating focal AT using a three-dimensional noncontact mapping system. METHODS AND RESULTS: The study consisted of 7 patients (4 men and 3 women; age 44 +/- 29 years) with focal AT. Cycle length variation and atrial activation pattern at baseline and just before AT termination by adenosine (3-12 mg) were analyzed. Noncontact mapping demonstrated focal AT propagated from the origin (O) with preferential conduction and spread away from the breakout sites to the whole atrium. Compared to baseline AT, termination episodes revealed higher mean beat-to-beat variation of AT cycle length (11.7 +/- 11.7 msec vs 4.7 +/- 4.5 msec, P < 0.001) and standard deviation of normalized AT cycle length (0.033 +/- 0.014 vs 0.011 +/- 0.005, P < 0.001). In termination episodes, adenosine significantly decreased the peak negative voltage of AT-O (-27.2 +/- 15.3%, P < 0.01), preferential conduction (proximal: -32.1 +/- 18.7, mid: -28.4 +/- 22.8, distal portion: -29.6 +/- 21.4%, P < 0.01), and breakout (-31.4 +/- 12.5%, P < 0.01). However, adenosine did not affect voltage in nontermination episodes. Adenosine shifted the locations of AT-O in 5 of 10 AT episodes with termination. Mean number of shifting AT-O was 2.4 +/- 1.5 (range 1-4), with maximum shifting distance of 15.0 +/- 3.1 (range 10-19) mm. Focal activation at AT-O simply disappeared in all termination episodes and therefore was not due to conduction block within preferential conduction or breakout site. Catheter ablation lesions covered 50% of total shifting origins, without late recurrence. CONCLUSION: Adenosine-induced AT termination was associated with significantly decreased electrogram voltage, shifting AT-O locations, and disappearance of focal activation.

Adenosine↗
PubMed2004

Development of atrial fibrillation in patients with atrioventricular block after atrioventricular synchronized pacing.

Many studies have evidenced an increased incidence of AF in patients receiving single chamber ventricular pacing (VVI) when compared with those undergoing an atrial-based system (AAI or DDD). However, the difference in incidence of AF between two atrial-based systems (VDD, DDD) in patients with AV block was still controversial. This study was conducted to compare the development of AF between different modes of pacemakers (VDD and DDD) in patients with symptomatic AV block. A retrospective review was conducted of the detailed records of all consecutive patients who received permanent pacemakers due to symptomatic bradycardia from March 1995 to March 2000. The occurrence of AF was documented when there was presence of AF in the free-run or 12-lead ECG, any ECG strips, or persistent AF on 24-hour Holter ECG during the follow-up. The study included 152 patients (44 women, 108 men; mean age 73). The patients were divided into two groups: VDD (n = 100) and DDD (n = 52). The mean follow-up was 48.9 +/- 22.9 months. The incidence of AF was 7.9%. A higher incidence of AF was noted in the DDD group (15.4%) when compared with the VDD group (4.0%, P = 0.023). The incidence of development of AF in patients with AV block was higher in those receiving DDD cardiac pacing when compared with those who received the VDD system. The authors suggest that VDD pacing may be a better choice than the DDD system for patients with AV block, but without clinical evidence of sinus node dysfunction, and if an atrial lead is required, it should be placed close to the Bachmann's bundle.

Adult↗
PubMed2004

Electrophysiological mechanisms and catheter ablation of complex atrial arrhythmias from crista terminalis:.

Paroxysmal atrial fibrillation (PAF) can be initiated by ectopic activation from the crista terminalis. The crista terminalis conduction gap is also a critical isthmus in atrial reentrant arrhythmias like upper and lower loop reentry. The aim of this study was to investigate the mechanism and results of catheter ablation for complex atrial arrhythmias originating from the crista terminalis using the noncontact mapping system (NCM). The study population consisted of six patients (5 men, 1 woman; 70 +/- 9 years) with drug refractory PAF and typical/atypical atrial flutter. NCM identified the earliest ectopic activation originating from the crista terminalis in these six patients. The reentry circuit of atypical atrial flutter propagated around the upper crista terminalis in five patients, and lower crista terminalis in one patient. The reentry circuit of atypical atrial flutter and the initial reentry circuit of AF conducted through the crista terminalis gap in all patients. Radiofrequency applications were delivered on the sites of ectopy, which initiated AF. Substrate modification was also performed over the crista terminalis gap (six patients) and cavotricuspid isthmus (three patients) responsible for the reentry. During a mean follow-up of 9 +/- 5 months (range 5-18 months), five patients were free of AF without antiarrhythmic drugs, and one patient did not have AF or atrial flutter using propafenone. NCM demonstrated the mechanism of crista terminalis ectopy-initiating AF and associated typical/atypical atrial flutter. Catheter ablation of crista terminalis ectopy and substrate for the reentry guided by NCM successfully eliminated these atrial arrhythmias.

Aged↗