Search PubMed⌕ Search

Biomedical subjects

C E Chiang

Publications and source records attributed to C E Chiang.

At least 73 records · Page 4Linked to original sources
PubMed1996

Efficiency of heating during radiofrequency catheter ablation of accessory atrioventricular pathways.

Adequate heating with myocardial thermal injury is necessary for successful ablation. This study was designed to examine the relationship between power, temperature, and efficiency of heating during radiofrequency catheter ablation of accessory pathways in 76 patients. During each application of radiofrequency energy, temperature was continually monitored by use of an ablation catheter with a thermistor embedded in the tip of the distal electrode. The efficiency of heating varied by location, with the greatest efficiency of heating for posteroseptal energy applications (2.7 +/- 2.3 degrees C/W), which were significantly greater than for left-sided (2.1 +/- 1.9 degrees C/W, P < 0.01) or right-sided (1.0 +/- 1.1 degrees C/W, P < 0.01) applications. For patients with left free wall and posteroseptal pathways, the temperature, radiofrequency power, time to peak temperature and efficiency of heating were similar between the successful and unsuccessful pulses. However, the mean temperature (53.5 +/- 4.5 vs. 45.1 +/- 5.1 degrees C, P < 0.01) and radiofrequency power (49.6 +/- 5.2 vs. 40.3 +/- 10.2 watt, P < 0.05) differed significantly between the successful and unsuccessful ablation pulses in patients with right free wall pathways. To achieve greater efficiency of heating and higher temperature, it is reasonable to use higher power outputs (40-50 W) in radiofrequency ablation of right free wall pathways, whereas less power outputs (30-40 W) are likely to produce adequate heating of posteroseptal and left free wall pathways, and minimize the risk of impedance rise and coagulum formation.

Adolescent↗
PubMed1996

Multiple anterograde atrioventricular node pathways in patients with atrioventricular node reentrant tachycardia.

OBJECTIVES: This study sought to investigate electrophysiologic characteristics and possible anatomic sites of multiple anterograde slow atrioventricular (AV) node pathways and to compare these findings with those in dual anterograde AV node pathways. BACKGROUND: Although multiple anterograde AV node pathways have been demonstrated by the presence of multiple discontinuities in the AV node conduction curve, the role of these pathways in the initiation and maintenance of AV node reentrant tachycardia (AVNRT) is still unclear, and possible anatomic sites of these pathways have not been reported. METHODS: This study included 500 consecutive patients with AVNRT who underwent electrophysiologic study and radiofrequency ablation. Twenty-six patients (5.2%) with triple or more anterograde AV node pathways were designated as Group I (16 female, 10 male, mean age 48 +/- 14 years), and the other 474 patients (including 451 with and 23 without dual anterograde AV node pathways) were designated as Group II (257 female, 217 male; mean age 52 +/- 16 years). RESULTS: Of the 21 patients with triple anterograde AV node pathways, AVNRT was initiated through the first slow pathway only in 3, through the second slow pathway only in 8 and through the two slow pathways in 9. Of the five patients with quadruple anterograde AV node pathways, AVNRT was initiated through all three anterograde slow pathways in three and through the two slower pathways (the second and third slow pathways) in two. After radiofrequency catheter ablation, no patient had inducible AVNRT. Eleven patients (42.3%) in Group I had multiple anterograde slow pathways eliminated simultaneously at a single ablation site. Eight patients (30.7%) had these slow pathways eliminated at different ablation sites; the slow pathways with a longer conduction time were ablated more posteriorly in the Koch's triangle than those with a shorter conduction time. The remaining seven patients (27%) had a residual slow pathway after delivery of radiofrequency energy at a single or different ablation sites. The patients in Group I had a longer tachycardia cycle length, poorer retrograde conduction properties and a higher incidence of multiple types of AVNRT than those in Group II. CONCLUSIONS: Multiple anterograde AV node pathways are not rare in patients with AVNRT. However, not all of the anterograde slow pathways were involved in the initiation and maintenance of tachycardia. Radiofrequency catheter ablation was safe and effective in eliminating critical slow pathways to cure AVNRT.

Adult↗
PubMed1996

Electrophysiologic characteristics, electropharmacologic responses and radiofrequency ablation in patients with decremental accessory pathway.

OBJECTIVES: This study sought to characterize the functional properties of decremental accessory atrioventricular (AV) pathways and to investigate their pharmacologic responses. BACKGROUND: Although decremental AV pathways associated with incessant reciprocating tachycardia have been studied extensively, information about the electrophysiologic characteristics and pharmacologic responses of anterograde and retrograde decremental AV pathways is limited. METHODS: Of 759 consecutive patients with accessory pathway-mediated tachyarrhythmia, 74 with decremental AV pathways were investigated (mean age 43 +/- 18 years). After baseline electrophysiologic study, the serial drugs adenosine, verapamil and procainamide were tested during atrial and ventricular pacing. Finally, radiofrequency catheter ablation was performed. RESULTS: Five patients had anterograde decremental conduction over the accessory pathway but had no retrograde conduction. Of the 64 patients with retrograde decremental conduction over the accessory pathway, anterograde conduction over the pathway was absent in 41 (64%), intermittent in 5 (8%) and nondecremental in 18 (28%). In the remaining five patients, anterograde and retrograde decremental conduction over the same pathway was found. The anterograde and retrograde conduction properties and extent of decrement did not differ between anterograde and retrograde decremental pathways. Posteroseptal pathways had the highest incidences of anterograde and retrograde decremental conduction. Intravenous adenosine, procainamide and verapamil caused conduction delay or block, or both, in 10 of 10, 10 of 10 and 4 of 10 of the anterograde and 20 of 20, 20 of 20 and 8 of 20 of the retrograde decremental pathways, respectively. All patients had successful ablation of the decremental pathways without complications. During the follow-up period of 31 +/- 19 months, only one patient experienced recurrence. CONCLUSIONS: Decremental accessory pathways usually had functionally distinct conduction characteristics in the anterograde and retrograde directions. Their pharmacologic responses suggested the heterogeneous mechanisms of decremental conduction.

Adenosine↗
PubMed1996

Comparisons of oral propafenone and quinidine as an initial treatment option in patients with symptomatic paroxysmal atrial fibrillation: a double-blind, randomized trial.

OBJECTIVE: The main aim of the study was to evaluate the safety and efficacy of propafenone versus quinidine as an initial choice in treatment of symptomatic paroxysmal atrial fibrillation. DESIGN: The study consisted of a 3-month treatment with oral propafenone hydrochloride or quinidine sulphate in patients with paroxysmal symptomatic atrial fibrillation, according to a double-blind randomized system. SETTING: The study was performed in the out-patient clinic of university hospital. MAIN OUTCOME MEASURES: The effects of the two drugs on attack frequency, ventricular rate and symptoms of symptomatic paroxysmal atrial fibrillation. RESULTS: In the oral propafenone group (n = 48), two patients (4%) discontinued the treatment because of dizziness. In the 46 patients who continued the treatment, the attack frequency decreased from 11 +/- 3 times per week at baseline to 1 +/- 1 times per week after treatment (P < 0.01). Forty (87%) out of the 46 patients had effective response to oral propafenone (more than 75% reduction of symptomatic arrhythmic attacks) on a mean dose of 615 +/- 10 mg day-1; the decrease in attack frequency was from 10 +/- 3 to 1 +/- 1 times per week. Twenty-three (50%) patients were free from recurrence of symptomatic paroxysmal atrial fibrillation. Comparisons of symptom scores for patients (n = 23) with attacks of paroxysmal atrial fibrillation after oral propafenone treatment showed that there was a significantly lower symptom score of palpitation, asthenia, effort dyspnea, dizziness, rest dyspnea and chest oppression in attacks of paroxysmal atrial fibrillation after propafenone treatment (11.05 +/- 3.78 versus 7.60 +/- 3.46, P < 0.01). From the oral quinidine group (n = 48), two patients (4%) discontinued treatment because of gastrointestinal discomfort. In the 46 patients who continued the treatment, the attack frequency decreased from 11 +/- 4 times per week at baseline to 3 +/- 2 times per week after treatment (P < 0.01). Twenty-one (46%) out of the 46 patients had effective response to oral quinidine on a mean dose of 1067 +/- 462 mg day-1, with a decrease in attack frequency from 12 +/- 3 to 1 +/- 1 times per week. Only 10 (22%) patients were free from recurrence of paroxysmal atrial fibrillation. Comparisons of symptom scores for patients (n = 36) with attacks of paroxysmal atrial fibrillation after quinidine treatment showed that there was no significant decrease of symptom score in attacks of atrial fibrillation (10.65 +/- 3.92 versus 10.20 +/- 3.80, P = 0.57). Furthermore, the percentage decrease of ventricular rate during atrial fibrillation was significantly greater in patients with propafenone (-25 +/- 4% versus -8 +/- 3%, P < 0.01). CONCLUSIONS: Oral propafenone appeared to be more effective than quinidine in suppressing attacks and alleviating symptoms of paroxysmal atrial fibrillation.

Administration, Oral↗
PubMed1996

Electrophysiologic characteristics and anatomical complexities of accessory atrioventricular pathways with successful ablation of anterograde and retrograde conduction at different sites.

INTRODUCTION: Catheter ablation may eliminate anterograde and retrograde accessory pathway conduction at closely adjacent but anatomically discrete sites. However, the mechanisms of this discrepancy, the electrophysiologic and anatomical characteristics, and information about systematic study from a large patient population are not available. The purpose of this study was to investigate the electrophysiologic characteristics and anatomical complexities of the accessory pathway in which anterograde and retrograde conduction was successfully ablated at different sites. METHODS AND RESULTS: Thirty-eight (10.9%) patients (19 men and 19 women; mean age 37 +/- 2.4 years) fulfilling the criteria of having separate ablation sites for anterograde and retrograde conduction were designated as group I, and the other 310 patients (215 men and 95 women; mean age 47 +/- 0.6 years) were designated as group II. The patients with right-sided free-wall pathways had the highest incidence (18.6%) of separate ablation sites. The anatomical distance between anterograde and retrograde directions (left anterior oblique view, 13 +/- 0.6 vs 8 +/- 0.9 mm, P < 0.01; right anterior oblique view, 17 +/- 0.6 vs 5 +/- 0.7 mm, P < 0.01), and incidence of conduction impairment in one direction after successful ablation of another direction (15% vs 78%, P < 0.05) differed significantly between left and right free-wall pathways. The mean distances obtained from left (7 +/- 0.4 vs 14 +/- 0.4 mm, P < 0.05) and right (7 +/- 1.1 vs 15 +/- 0.9 mm, P < 0.05) anterior oblique views were shorter in patients who had impairment of conduction properties than those in patients without impaired conduction after successful ablation of one direction. CONCLUSIONS: This study showed that anatomical and functional dissociation of the accessory pathway into anterograde and retrograde components was possible. Further study on the relation between electrophysiologic and pathologic characteristics would be helpful to confirm these findings.

Adolescent↗
PubMed1996

Dimension and related anatomical distance of Koch's triangle in patients with atrioventricular nodal reentrant tachycardia.

INTRODUCTION: The dimension of Koch's triangle in patients with AV nodal reentrant tachycardia has not been well described. Understanding the dimension and anatomical distance related to Koch's triangle might be useful in avoiding accidental AV block during ablation of the slow pathway. The purposes of this study were to define the dimension of Koch's triangle and its related anatomical distance and correlate these parameters with the successful ablation sites in patients with AV nodal reentrant tachycardia. METHODS AND RESULTS: We studied 218 patients with AV nodal reentrant tachycardia. The distance between the presumed proximal His-bundle area and the base of the coronary sinus orifice (DHis-OS) measured in the right anterior oblique view was used to define the dimension of Koch's triangle. The distance of the proximal His-bundle recording site from the successful ablation site (DHis-Ab) and the distance as a fraction of the entire length of Koch's triangle (DHis-Ab/DHis-Os) were determined. The mean DHis-Os and DHis-Ab were 25.9 +/- 7.9 and 13.4 +/- 3.8 mm, respectively. DHis-Os negatively correlated with patient age (r = -0.41, P < 0.0001) and body mass index (r = -0.18, P = 0.004). Among the patients with successful ablation sites in the medial area, DHis-Os was longer (27.2 +/- 6.6 vs 24.6 +/- 8.4 mm, P < 0.005), DHis-Ab was similar (12.9 +/- 3.1 vs 13.9 +/- 4.0, P > 0.05) and DHis-Ab/DHis-Os was smaller (0.48 +/- 0.04 vs 0.74 +/- 0.11, P < 0.05). Furthermore, the patients with successful ablation sites in the medial location needed more radiofrequency pulse numbers than those in the posterior location (6 +/- 4 vs 4 +/- 3, P < 0.05). CONCLUSION: The site of successful slow pathway ablation was consistently about 13 mm from the site recording the proximal His-bundle deflection in patients with AV nodal reentrant tachycardia despite marked variability in the dimensions of Koch's triangle; therefore, patients with large triangles required ablation in the medial region rather than the posterior region. Care should be taken when delivering radiofrequency energy to the posteroseptal area in patients with shorter DHis-Os to avoid injury to AV node.

Adolescent↗
PubMed1996

Temperature monitoring in radiofrequency catheter ablation of atrial flutter using the linear ablation technique.

INTRODUCTION: Information about temperature and impedance monitoring during radiofrequency catheter linear ablation of atrial flutter has not been reported. We proposed that a radiofrequency catheter ablation system using a closedloop temperature control model could decrease the incidence of coagulum formation and shorten the radiation exposure and procedure times compared with those found in a power control model. METHODS AND RESULTS: Forty patients (8 women and 32 men; mean age 64 +/- 7 years) with atrial flutter were referred for radiofrequency ablation. The patients were randomized into two groups: group I patients underwent radiofrequency catheter linear ablation of atrial flutter using a power control of energy output model; and group II patients underwent the closedloop temperature control model with a target electrode temperature of 70 degrees C. As compared with group II, group I patients had a higher incidence of coagulum formation (12% vs 2%, P < 0.05), temperature shutdown (11% vs 0%, P < 0.01), and impedance shutdown (16% vs 3%, P < 0.01), more radiofrequency applications (7 +/- 3 vs 4 +/- 2, P < 0.01), and longer procedure time (100 +/- 25 vs 75 +/- 23 minutes, P < 0.05) and radiation exposure time (31 +/- 10 vs 20 +/- 7 minutes, P < 0.05) required for successful ablation. Larger deviations of temperature (9.0 degrees +/- 2.4 degrees C vs 5.0 degrees +/- 1.2 degrees C, P < 0.0001) and impedance (9.2 +/- 2.6 omega vs 5.3 +/- 1.6 omega, P < 0.0001) were also found in group I patients compared with those in group II. CONCLUSIONS: This study demonstrated that a closed-loop temperature control model could facilitate the effects of radiofrequency catheter ablation of the atrial flutter circuit by decreasing coagulum formation, temperature and impedance shutdown, and procedure and radiation exposure times.

Adult↗
PubMed1996

Paradox of accessory pathway block after radiofrequency ablation in patients with the Wolff-Parkinson-White syndrome.

Although pacing technique has demonstrated that the most common site of conduction block in a manifest accessory pathway (AP) was between the AP and the ventricle, most of the block sites have been found to be between the atrium and AP after successful radiofrequency ablation. Furthermore, the block site in a concealed AP after successful radiofrequency catheter ablation has not been reported in the literature, and comparisons between a manifest and concealed AP have not been performed. This study included 219 consecutive patients undergoing successful radiofrequency catheter ablation of a single AP. AP potential was recorded at the successful target site in 76 of 92 (82.6%) patients with manifest APs, and in 99 of 127 (77.9%) patients with concealed APs. All the left-sided APs (including left posteroseptal APs) were ablated by a ventricular approach, and right-sided APs (including anteromidseptal and right posteroseptal APs) were ablated by an atrial approach. The site of conduction block was determined by analyzing and comparing the local electrograms recorded before and after radiofrequency ablation at successful ablation sites. Conduction block of manifest APs was between the atrial-AP (A-AP) in 69 patients (75%) and between the AP-ventricle (AP-V) interface in 7 patients (7.6%), whereas the conduction block of concealed APs occurred between the AP-V in 90 patients (70.9%) and between the A-AP interface in 9 patients (7.1%). Neither the preablation electrogram nor electrophysiologic characteristics of APs predicted the site of conduction block. Furthermore, neither the location of the APs nor the position of the ablation catheter affected the block site. It was concluded that the most common site of conduction block during successful radiofrequency catheter ablation of a manifest and concealed AP was between the A-AP and AP-V interface, respectively, and the impedance mismatch theory explained only part of the findings.

Adult↗
PubMed1996

Electrocardiographic and electrophysiologic characteristics of anteroseptal, midseptal, and para-Hisian accessory pathways. Implication for radiofrequency catheter ablation.

STUDY OBJECTIVE: To investigate the ECG characteristics, the electrophysiologic properties, and an effective radiofrequency catheter ablation technique in patients with septal accessory pathways. PATIENTS: Forty-six consecutive subjects with septal accessory pathways located in the anteroseptal, midseptal, and para-Hisian areas. DESIGN AND INTERVENTIONS: ECGs obtained during sinus rhythm and orthodromic tachycardia, conduction properties obtained from electrophysiologic study, and results of two different ablation techniques were analyzed. MEASUREMENTS AND RESULTS: (1) Twenty-four (52.2%) had manifest preexcitation and 15 (32.6%) had multiple accessory pathways; (2) midseptal pathways could be differentiated from anteroseptal and para-Hisian pathways by a negative delta wave in lead III and a biphasic delta wave in lead aVF during sinus rhythm, and a negative retrograde P wave in two inferior leads during orthodromic tachycardia; (2) midseptal pathways had better antegrade conduction properties and a significantly higher incidence (61.5%) of inducible atrial fibrillation; (4) radiofrequency catheter ablation using lower energy (20+/-6 W) had a comparable effect to ablation using higher energy (36+/-5 W), but without impairment of atrioventricular (AV) node conduction or development of AV block; and (5) during the follow-up period of 26+/-14 months (range, 5 to 54 months), three (6.5%) patients had recurrence. CONCLUSIONS: Midseptal accessory pathways had ECG and electrophysiologic characteristics that were distinctive from those of anteroseptal and para-Hisian pathways. Catheter ablation of these septal pathways using low radiofrequency energy was safe and effective.

Adolescent↗
PubMed1996

Accessory atrioventricular pathway at the antero-medial mitral annulus--electrophysiologic characteristics and radiofrequency catheter ablation: a case report.

Accessory atrioventricular (AV) pathway located at or near the region of aorta-mitral continuity has rarely been mentioned. This report describes one such case with a concealed accessory AV pathway at the anteromedial mitral annulus adjacent to aorta-mitral continuity. The location of the accessory pathway was confirmed by successful radiofrequency catheter ablation. This patient was a 26-year-old male. His 12-lead surface ECG showed no evidence of ventricular preexcitation during sinus rhythm. The earliest retrograde atrial depolarization recorded from the routine catheters was at the His bundle area during ventricular pacing and orthrodromic AV reentrant tachycardia; paradoxically, the earliest left-sided atrial activation recorded from the coronary sinus catheters was at the distal coronary sinus area. The unique retrograde atrial activation sequence over the left atrium and His bundle area was not true for patients with left lateral or anterolateral accessory pathway. During tachycardia, the local electrogram from the successful ablation site showed local VA fusion in the anteromedial mitral annulus. After delivering one pulse of radiofrequency energy (30W), the accessory AV pathway was successfully eliminated without complication. This report presents a concealed left-sided accessory AV pathway at an unusual location. It is very important to describe special electrophysiologic characteristics and ablation technique in this unusual accessory pathway to improve knowledge in the era of interventional electrophysiology.

Adult↗
PubMed1995

Effects of pregnancy on first onset and symptoms of paroxysmal supraventricular tachycardia.

It is important for women to understand the risk of first onset and symptomatic exacerbation of paroxysmal supraventricular tachycardia (SVT) during pregnancy. Reports regarding the effects of pregnancy on first onset and symptomatic exacerbation of paroxysmal SVT have been controversial, and have not been conducted in a systematic fashion. Two hundred seven consecutive female patients diagnosed with symptomatic paroxysmal SVT were requested to respond to multiple questionnaires before electrophysiologic study and catheter ablation. A person-years data method was used to estimate risk of first onset of paroxysmal SVT during pregnancy. Exacerbation of paroxysmal SVT was assessed by a score scale including each of the following symptoms: palpitation, fatigue, rest dyspnea, effort dyspnea, dizziness, chest oppression, blurred vision, and syncope (total score change > 2 points). In the 107 patients with accessory pathway-mediated tachycardia, 7 patients had had a first onset of tachycardia during pregnancy (relative risk ratio 0.86, confidence interval 0.4 to 1.9, p = 0.35). In the 100 patients with atrioventricular nodal reentrant tachycardia, 1 patient had had the first onset of tachycardia during pregnancy (relative risk ratio 0.11, confidence interval 0.02 to 0.56, p = 0.004). Otherwise, 14 of the 63 patients (22%) with tachycardia in the pregnant and nonpregnant periods had exacerbation of symptoms during pregnancy. Thus, first onset of paroxysmal SVT during pregnancy was rare (3.9%), and pregnancy was associated with a low risk of first onset of paroxysmal SVT. However, symptoms of paroxysmal SVT were exacerbated during pregnancy in some patients.

Adolescent↗
PubMed1995

Recurrent tachycardia after selective ablation of slow pathway in patients with atrioventricular nodal reentrant tachycardia.

Recurrence rate of atrioventricular (AV) nodal reentrant tachycardia after successful radiofrequency ablation varies widely, and the determinants of recurrent AV nodal reentrant tachycardia remain controversial. Furthermore, true or pseudorecurrence of tachycardia after successful ablation in patients with different forms of AV nodal reentrant tachycardia has not been evaluated systematically. Three hundred sixty-two patients (161 men and 201 women [mean age 52 +/- 16 years]), including 314 patients with typical-form, 10 patients with atypical-form, 4 patients with variant-form, and 34 patients with multiple-form AV nodal reentrant tachycardias, received selective radiofrequency ablation of the anterograde and/or retrograde slow AV nodal pathway. During a mean follow-up of 27 +/- 11 months, 9 patients (2.5%) experienced recurrent AV nodal reentrant tachycardia (true recurrence, group A), and 8 (2.2%) had inappropriate sinus tachycardia or paroxysmal atrial tachyarrhythmias (pseudorecurrence, group B). Neither the true nor pseudorecurrence rate was different among the 4 different forms of tachycardia. Factors including presence of residual slow pathway conduction, a single AV nodal reentrant echo beat, absence of an accelerated junctional rhythm during successful ablation, facilitating induction of tachycardia by isoproterenol, radiofrequency pulse number, and successful ablation site were not associated with an increased risk of recurrent AV nodal reentrant tachycardia. The onset time of recurrent tachycardia was significantly late in group B patients (30 +/- 21 vs 292 +/- 240 days, p = 0.04). Thus, this study demonstrated that both true and pseudorecurrence could occur after successful ablation.

Adolescent↗
PubMed1995

An accurate stepwise electrocardiographic algorithm for localization of accessory pathways in patients with Wolff-Parkinson-White syndrome from a comprehensive analysis of delta waves and R/S ratio during sinus rhythm.

Prediction of accessory pathway location before radio-frequency ablation has become increasingly important for patients with Wolff-Parkinson-White syndrome. However, existing electrocardiographic (ECG) criteria for localization of accessory pathways have several limitations, and the polarity of delta waves has not been well defined. In the present study, 369 patients with a single anterogradely conducting accessory pathway who underwent successful radiofrequency ablation were included. The polarity of delta waves was defined and categorized in detail, and various ECG characteristics of the most preexcited QRS complexes were examined and compared with QRS complexes after successful ablation in the initial 182 patients, which included morphology and polarity of delta waves, initial 20, 40, and 60 ms segments of the preexcited QRS complex, R/S ratio in the precordial leads, R/S ratio in the frontal leads, delta wave axis in the frontal plane, polarity of delta waves in the frontal leads, and polarity of delta waves in the precordial leads. The polarity of the initial 40 ms segment of the most preexcited QRS complexes in each of the frontal leads, and the polarity of the initial 60 ms segment of the most preexcited QRS complex in each of the precordial leads proved to be the best representatives of delta wave polarity in the respective leads.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗
PubMed1995

Radiofrequency catheter ablation of paroxysmal supraventricular tachycardia in patients with congenital heart disease.

Radiofrequency catheter ablation was performed in 21 patients who had congenital heart diseases associated with accessory pathway (AP)-mediated tachycardia (14 patients), with atrioventricular (AV) nodal reentrant tachycardia (4 patients), with intraatrial reentrant tachycardia (1 patient), with coexistent AP mediated tachycardia and AV nodal reentrant tachycardia (1 patient) and with coexistent AV nodal reentrant tachycardia and atrial tachycardia (1 patient). Congenital heart diseases diagnosed were seven with Ebstein's anomaly and six with septal defect; the others included patent ductus arteriosus, supravalvular aortic stenosis and left superior vena cava-coronary sinus fistula. Incidence of multiple APs (26.7 vs. 7.7%, P = 0.027), antidromic tachycardia (20.0 vs. 2.9%, P = 0.011), tachyarrhythmia-related syncope (26.7 vs. 7.2%, P = 0.022) and cardiac arrest (13.3 vs. 0%, P = 0.001) was higher in patients with AP and congenital heart diseases. Longer procedure (3.9 +/- 0.7 vs. 2.4 +/- 1.3 h for AP, P = 0.001; 3.0 +/- 0.7 vs. 2.5 +/- 0.8 h for AV nodal reentrant tachycardia, P = 0.001), and radiation exposure times (102 +/- 27 vs. 35 +/- 23 min for AP, P = 0.001; 62 +/- 23 vs. 20 +/- 11 min for AV nodal reentrant tachycardia, P = 0.001) were necessary to achieve a high success rate (95%) in patients with congenital heart disease.

Adolescent↗
PubMed1995

Initial onset of accessory pathway-mediated and atrioventricular node reentrant tachycardia after age 65: clinical features, electrophysiologic characteristics, and possible facilitating factors.

OBJECTIVE: To evaluate the clinical features electrophysiologic characteristics, and possible facilitating factors in older patients (> or = 65 years) with initial onset of accessory pathway-mediated and atrioventricular (AV) node reentrant tachycardia. DESIGN: Of the patients undergoing electrophysiologic study and radiofrequency catheter ablation of accessory pathway-mediated and AV node reentrant tachycardia at this institution, patients with initial tachyarrhythmia after age 65 years were compared with those presenting initially before age 30. SETTING: A tertiary medical center for the general public. PARTICIPANTS: Sixty-six patients had their initial symptoms after age 65: Group I, 32 patients with accessory pathway-mediated tachycardia, and Group II, 34 patients with AV node reentrant tachycardia. Four-hundred forty patients had their initial symptoms before age 30: Group III, 283 with accessory pathway mediated tachyarrhythmia, and Group IV, 157 with AV node reentrant tachycardia. INTERVENTION: All patients underwent electrophysiological study to determine the mechanisms of tachyarrhythmia, and radiofrequency catheter ablation for treatment of tachycardia. RESULTS: (1) Older patients with initial arrhythmia had incidence of critical clinical manifestations, including tachyarrhythmia-related syncope and cardioversion, similar to those with initial arrhythmia at a younger age. (2) Patients in Group III, showed anterograde effective refractory period (ERP) of the AV node (P = .432), longer anterograde ERP of the accessory pathway (P = .004), and greater difference of the anterograde ERP between the AV node and the accessory pathway (D-ERP) (P = .003) similar to patients in group I. In Group II, the ERP and Wenckebach cycle length of the retrograde fast pathway was significantly longer than in Group IV (P = .037 and P < .001, respectively), and a greater percentage of patients in Group II than in Group IV AV node reentrant tachycardia needed isoproteronol to facilitate the induction of reentrant tachycardia (P = .034). (3) Patients in Group I and Group II had a higher incidence of supraventricular and ventricular ectopic activity than those in Group III (P = .002 and P = .005, respectively) and Group IV (P = .024 and P = .012, respectively) in 24-hour ambulatory electrocardiograms. CONCLUSION: The initial onset of accessory pathway-mediated tachycardia after age 65 may be caused by changes of electrophysiologic properties (greater D-ERP) as well as increased supraventricular and ventricular ectopic activity. Influence of the autonomic nervous system, rather than changes of conduction properties in the AV node, and increase in ectopic activity may contribute to the new onset of AV node reentrant tachycardia in older adults. The choice of antiarrhythmic drugs and radiofrequency ablation require attention to the clinical profile and facilitating factors of reentrant tachycardia in this group of patients.

Adult↗
PubMed1995

Future ablation concepts of tachyarrhythmias.

Application of radiofrequency energy to arrhythmogenic substrates after careful cardiac mapping could ensure a high success rate in eliminating certain types of tachyarrhythmias. Future studies of catheter ablation will focus on how to improve ablation efficacy and achieve a better result in various types of tachyarrhythmias. More information about the arrhythmogenic mechanisms will be provided to improve the knowledge of diagnostic and interventional electrophysiology.

Arrhythmias, Cardiac↗
PubMed1995

Accessory atrioventricular pathways and atrioventricular nodal reentrant tachycardia in teenagers. Electrophysiologic characteristics and radiofrequency catheter ablation.

UNLABELLED: Accessory pathway-mediated tachyarrhythmias and AV nodal reentrant tachycardia represent a large portion of supraventricular tachycardia in younger patients. Reports comparing electrophysiologic characteristics and results of radiofrequency ablation between teenagers and adults from the same electrophysiology laboratory are rare, and these deserve further study. This study included 49 teenage patients (mean age 17 +/- 3 years, range from 10 to 20) and 1008 adult patients (mean age 50 +/- 13 years, range from 21 to 92) referred for electrophysiologic study and radiofrequency ablation for treatment of accessory pathway-mediated and AV nodal reentrant tachycardia. The results showed that: (1) mean duration of tachyarrhythmia was shorter in teenagers, but incidences of syncope, cardioversion for hemodynamic compromise and associated cardiovascular diseases were similar in both groups; (2) teenagers had a higher incidence of right-sided free wall accessory pathways (34.1% vs 14.9%, p = 0.048) and better conduction properties of accessory pathways and AV nodal pathways; (3) fast-slow and multiple forms of AV nodal reentrant tachycardia were significantly less frequent (p = 0.026) in teenagers, whereas atrial fibrillation with ventricular preexcitation was common in adults; (4) success rate, incidence of recurrent tachycardia, total procedure time, radiation exposure time and number of radiofrequency pulses for successful ablation did not differ significantly between teenagers and adults. IN CONCLUSION: (1) different electrophysiologic characteristics were found between teenagers and adults; and (2) radiofrequency ablation was effective and safe in teenagers with paroxysmal supraventricular tachycardia.

Adolescent↗