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Biomedical subjects

M S Wen

Publications and source records attributed to M S Wen.

At least 37 records · Page 2Linked to original sources
PubMed1995

Radiofrequency ablation therapy in concealed left free wall accessory pathway with decremental conduction.

An electrophysiologic study followed by transcatheter radiofrequency ablation therapy was performed in two adult patients with a permanent form of junctional tachycardia. Both patients had no structural heart disease and exhibited a normal resting ECG. The P wave during tachycardia was negative in leads 1, 3, and aVF, biphasic over V6, and positive in V1 and aVL in both patients, while the P-R/R-P interval ratio during tachycardia was 0.82 and 0.36, respectively, in both patients. Both patients displayed an eccentric atrial activation sequence with the earliest atrial activation occurring at the distal coronary sinus and a decremental retrograde conduction property during incremental ventricular pacing, suggesting the presence of a concealed slowly conducting left free wall accessory pathway. The tachycardia used the normal atrioventricular pathway for anterograde conduction and the concealed show left accessory pathway for retrograde conduction. It was terminated following adenosine administration in both patients; termination of tachycardia was due to a block in the retrograde accessory pathway in one patient and due to a block in the atrioventricular node in the other patient. Radiofrequency ablation was performed by the retrograde transaortic approach. The radiofrequency f4p4ent was delivered to the site of the earliest atrial activation during tachycardia at the ventricular aspect of the mitral annulus. The successful ablation site had a ventriculoatrial (VA) interval of 120 and 130 ms, respectively, and was located at the posterolateral and lateral aspects of the mitral annulus. Following ablation, there was no VA conduction; however, conduction through the normal atrioventricular pathway was noted during isoproterenol infusion in both patients. There was no induction of tachycardia. This study demonstrates that the permanent form of junctional tachycardia in adults can incorporate a concealed left free wall accessory pathway with a decremental property. Radiofrequency ablation therapy is effective and safe in this form of arrhythmia.

Adult↗
PubMed1994

Characteristics and radiofrequency ablation therapy of intermediate septal accessory pathway.

Fourteen patients (5%) with an intermediate septal accessory pathway were identified among 283 consecutive patients with the Wolff-Parkinson-White syndrome who had electrophysiologic study and radiofrequency ablation therapy. Nine were women and 5 were men (mean age 33 +/- 13 years). The resting electrocardiogram showed ventricular preexcitation in 8 patients and normal PR interval in 6. Anterograde and retrograde mapping studies revealed that the accessory pathway was para-Hisian in 11 patients and paranodal in 3. The accessory pathway was successfully ablated in 10 patients (9 para-Hisian and 1 paranodal) and damaged in 1 (para-Hisian). Treatment of 3 patients was complicated by transient atrioventricular (AV) block, of 1 by intermittent second-degree AV block, and of another by permanent complete AV block requiring implantation of a permanent pacemaker. Six patients underwent a follow-up electrophysiologic study 84 +/- 55 days after ablation; none had induction of tachycardia even after isoproterenol infusion. It is concluded that radiofrequency ablation therapy for intermediate septal accessory pathway is feasible. However, the success rate is only modest (71%), whereas complications with heart block (36%) or complete right bundle branch block (29%) are high. Thus, the procedure should be reserved for patients with life-threatening or troublesome symptomatic tachyarrhythmias.

Adolescent↗
PubMed1994

Radiofrequency ablation therapy in atypical or multiple atrioventricular node reentry tachycardias.

Electrophysiologic study and radiofrequency ablation therapy were performed in 23 patients with atypical (8 patients) or multiple (15) atrioventricular node reentry tachycardias. Dual pathways with anterograde fast and slow pathway conductions were demonstrated in 16 patients. Studies on retrograde conduction revealed the presence of three different pathways, including fast (15 patients), intermediate (17), and slow (16). The radiofrequency current was applied to the inferior aspect, one-third anterior two-thirds posterior between the His bundle and the ostium of the coronary sinus, of Koch's triangle along the tricuspid annulus in all patients. Application of the current resulted in selective ablation or modification of both retrograde intermediate and slow pathway conductions in 20 patients. In two patients retrograde fast pathway conduction was also modified. Complete atrioventricular block occurred in the remaining patient. Sixteen patients had no induction of tachycardia or echo, 4 had induction of a single echo, and 2 had induction of the slow-fast form tachycardia; one of those 2 patients underwent a second trial and was successful. A median application of 2 was delivered at a power of 25 +/- 5 W and a duration of 18 +/- 4 sec. The total fluoroscopic time was 25 +/- 21 minutes. The anterograde fast pathway conduction was unaffected; the shortest atrial paced cycle length that sustained 1:1 fast pathway conduction was 329 +/- 65 msec and 330 +/- 68 msec before and after ablation, respectively. A follow-up electrophysiologic study was performed in 16 patients 60 +/- 15 days after ablation. Eleven had no induction of tachycardia or echo, and five had induction of < 3 echoes. This study demonstrated that radiofrequency ablation with the inferior approach is effective and safe in atypical or multiple atrioventricular node reentry tachycardias. It resulted in ablation of the slow pathway and retrograde intermediate pathway conduction with preserved atrioventricular conduction.

Adult↗
PubMed1994

Late clinical and electrophysiologic outcome of radiofrequency ablation therapy by the inferior approach in atrioventricular node reentry tachycardia.

A late electrophysiologic study was conducted in 182 of 289 patients with slow-fast atrioventricular node reentry tachycardia 81 +/- 36 days after radiofrequency ablation therapy by the inferior approach. Of these 182 patients, electrophysiologic study immediately after ablation revealed a selective modification of the slow pathway in 159, a modification of both the slow and fast pathways in 15, a modification of the fast pathway alone in 3, and failure of ablation in 5. One hundred two patients had no induction of echoes; 75 had induction of fewer than four echoes; and 5 had induction of sustained tachycardia with or without isoproterenol infusion. The late electrophysiologic study in these 182 patients revealed a persistent effect without changes in conduction properties in 161 (88%) patients. A change in conduction properties was noted in 21 patients, including 5 with resumption of slow- or fast-pathway conduction with induction of sustained tachycardia, 8 with improved fast- or slow-pathway conduction, and 8 with an additional depression of fast- or slow-pathway conduction. Of the 102 patients with no induction of echoes and the 75 patients with induction of fewer than four echoes during the immediate postablation electrophysiologic study, 5 (3 and 2, respectively) patients had induction of tachycardia. Of the 5 patients with induction of sustained tachycardia in the immediate postablation electrophysiologic study, 3 continued to have induction of sustained tachycardia; 1 had induction of echoes only; and 1 had no induction of echoes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Double loop figure-of-8 reentry as the mechanism of multiple atrioventricular node reentry tachycardias.

Seven patients with multiple atrioventricular node reentry tachycardia were analyzed to unravel the mechanism of these tachycardias. Six of the seven patients showed anterograde dual atrioventricular node pathways and one showed anterograde conduction through the fast pathway. Three types of retrograde pathways were noted among these seven patients: (1) the fast pathway with the earliest atrial activation at the His bundle area; (2) the intermediate pathway with the earliest atrial activation at the ostium of the coronary sinus; and (3) the slow pathway with the earliest atrial activation at the ostium of the coronary sinus. All seven patients used the intermediate pathway for retrograde conduction. However, one patient showed evidence of retrograde slow pathway conduction with demonstrable retrograde dual pathways, and another showed evidence of retrograde fast pathway conduction with a shift of atrial activation sequence when conduction switched to the intermediate pathway. Four different types of reentry circuits using either the fast or the slow pathway as the anterograde limb and one of the three retrograde pathways as the retrograde limb were demonstrated in these seven patients, resulting in two types of tachycardias in four patients and three types of tachycardias in three patients. A change in tachycardia type could be induced with atrial or ventricular stimulation. A radiofrequency current delivered to the inferior aspect of Koch's triangle along the tricuspid anulus in five patients resulted in selective ablation or modification of the intermediate pathway or the slow pathway, with preservation of anterograde atrioventricular conduction and abolition of tachycardias. The findings suggest that a double loop figure-of-8 reentry circuit including a fast pathway, a slow pathway, and an intermediate pathway is responsible for multiple atrioventricular node reentry tachycardias.

Adult↗
PubMed1994

Increased frequency of apolipoprotein B signal peptide sp24/24 in patients with coronary artery disease. General allele survey in the population of Taiwan and comparison with Caucasians.

Apolipoprotein B (apoB) signal peptide (sp) polymorphism was characterized by polymerase chain reaction in blood samples of 58 coronary artery disease (CAD) patients and 319 control individuals of Chinese Han ethnic origin in Taiwan. In the CAD group, 77% of the observed alleles were sp27 (sp with 27 amino acids), and the remaining 23% sp24 (sp with 24 amino acids). The frequency distributions of the apoB sp allele in the control group were 0.81 for sp27 and 0.19 for sp24. The genotype distributions were 0.64 sp27/27, 0.26 sp27/24 and 0.10 sp24/24 in the CAD group; 0.64 sp27/27, 0.33 sp27/24 and 0.03 sp24/24 in the control group. The frequency of sp24/24 was significantly higher (p = 0.012) in the CAD group than in the control group. Several studies have shown that the frequency of sp24/24 is higher in hyperlipidemic than in normolipidemic groups. This marker is probably in linkage disequilibrium with some other atherogenic genes. Our study shows that the differences in both apoB signal peptide alleles and sp27/27 and sp27/24 genotype distributions are statistically significant between the Taiwanese and Caucasians.

Adult↗
PubMed1994

Radiofrequency ablation therapy in idiopathic left ventricular tachycardia with no obvious structural heart disease.

BACKGROUND: The feasibility and efficacy of radiofrequency ablation therapy in idiopathic left ventricular tachycardia has not been assessed in a large group of patients. METHODS AND RESULTS: Twenty consecutive patients with idiopathic left ventricular tachycardia and without structural heart disease underwent electrophysiological study, pharmacological interventions with administration of verapamil and adenosine, and radiofrequency ablation therapy. There were 17 men and 3 women with a mean age of 28 +/- 8 years. The QRS configuration during tachycardia was of right bundle branch block and superior axis in 13 patients, indeterminate axis in 6 patients, and right axis in 1 patient. The tachycardia was electrically inducible and responsive to verapamil but not to adenosine. Thirteen patients demonstrated entrainment. Activation and pace-mapping studies disclosed that the tachycardia originated from the inferior apical septum in 15 patients, the midseptum in 4 patients, and the anterior lateral wall of the left ventricle in 1 patient. Radiofrequency ablation was successful in 17 of the 20 patients (85%). The successful ablation sites were characterized by an endocardial activation time 30 milliseconds earlier than the onset of QRS during tachycardia and by a pace-mapping QRS similar to or closely resembling the tachycardia. All patients displayed sharp spikes preceding the local ventricular electrogram at the ablation site. However, these sharp spikes also were noted in 15 control patients and were not specific for this tachycardia; they persisted after ablation. There were no complications. A follow-up of 7 +/- 8 months in the 17 successfully ablated patients showed no symptomatic tachyarrhythmias without medications. Six patients underwent repeat electrophysiological study, and no induction of tachycardia was revealed. CONCLUSIONS: Radiofrequency ablation therapy is effective and safe in patients with idiopathic left ventricular tachycardia. It should be considered as the primary therapeutic modality in these patients.

Adult↗
PubMed1994

Concertina-like phenomenon in ventricular preexcitation due to spontaneous atrioventricular nodal Wenckebach periodicity.

Electrophysiologic study and radiofrequency ablation therapy were performed in a 28-year-old male patient with the Wolff-Parkinson-White syndrome and electrocardiographic manifestation of concertina phenomenon. His bundle recordings showed a sinus cycle length of 720 = ms with a cyclic variation of QRS morphologies of every 3 beats and an antidromic atrial echo following the last fully preexcited QRS complex. After successful radiofrequency ablation of a left posterior accessory pathway, spontaneous 3:2 atrioventricular nodal Wenckebach periodicity was noted and the mechanism of the concertina phenomenon was unraveled.

Adult↗
PubMed1994

Worsening of vasovagal syncope after beta-blocker therapy.

Head-up tilt test was done in a 27-year-old man with recurrent syncope of unexplained cause. Severe sinus bradycardia and hypotension accompanied by light-headedness, cold sweating, and nausea occurred at 80 degrees head-up position during 4 micrograms/min isoproterenol infusion. Oral propranolol, 160 mg/d, in four divided doses, effectively prevented the above-mentioned abnormal vasovagal reflexes; diltiazem was only partially effective while disopyramide, aminophylline, or atropine was ineffective in preventing the abnormal vasovagal reflexes induced by head-up tilt with isoproterenol infusion. However, the patient experienced ten episodes of syncope in 2 weeks after he was discharged from the hospital on a regimen of atenolol, 50 mg/d. His symptoms ameliorated immediately after discontinuation of atenolol therapy and he became free of severe symptoms while receiving fludrocortisone. Thus, we have documented a patient with worsening of vasovagal syncope after beta-blocker therapy.

Adrenergic beta-Antagonists↗
PubMed1993

Radiofrequency ablation in multiple accessory pathways and the physiologic implications.

The presence of multiple accessory pathways was noted in 24 of 210 consecutive patients (12 males and 12 females aged 15 to 77 years [mean +/- SD 43 +/- 16]) with the Wolff-Parkinson-White syndrome who underwent electrophysiologic study and radiofrequency ablation. Six had 3 and 18 had 2 accessory pathways. There were 25 manifest and 29 concealed accessory pathways. The location of the accessory pathways was in the left free wall in 22, the right free wall in 17, the left posterior portion of the ventricular septum in 8, the right posterior portion of the ventricular septum in 6, and the midseptum in 1. The success rate of accessory pathway ablation and the fluoroscopic time in these 24 patients with multiple accessory pathways were 89% and 78 +/- 66 minutes, respectively, whereas they were 98% (p < 0.01) and 36 +/- 37 minutes (p = 0.01) in the 186 patients with a single accessory pathway. The mean applications, the power level of the radiofrequency current and the application duration in these 24 patients were 21 +/- 22, 30 +/- 3 W, and 27 +/- 10 seconds, respectively. In the 186 patients with a single accessory pathway, they were 9 +/- 12 applications (p = 0.02), 30 +/- 4 W (p = NS) and 26 +/- 9 seconds (p = NS), respectively. Seventeen of the 24 patients had a follow-up electrophysiologic study 89 +/- 40 days after ablation, and 2 (12%) had resumption of a right and left accessory pathway conduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

A simple technique for selective radiofrequency ablation of the slow pathway in atrioventricular node reentrant tachycardia.

OBJECTIVES: A simple technique was designed for radiofrequency ablation therapy of atrioventricular (AV) node reentrant tachycardia. BACKGROUND: This technique was based on the hypothesis that slow pathway conduction reflects conduction through the compact node and its posterior atrial input. METHODS: A total of 100 consecutive patients were studied; there were 37 men and 63 women, with a mean age of 48 +/- 15 years. All 100 patients had induction of sustained tachycardia with (51 patients) or without (49 patients) administration of isoproterenol or atropine, or both. The ablation catheter was initially manipulated to record the largest His bundle deflection from the apex of Koch's triangle. It was then curved downward and clockwise to the area of the compact node when His deflection was no longer visible and the ratio of atrial to ventricular electrogram was < 1. The radiofrequency current was delivered from the 4-mm tip electrode a mean of 5 +/- 7 times at a power of 25 +/- 4 W for a duration of 21 +/- 4 s. The total fluoroscopic time was 19 +/- 11 min. RESULTS: Selective ablation (56 patients) or modification (26 patients) of the slow pathway without affecting anterograde and retrograde fast pathway conduction was achieved in 82 patients. Ablation or modification of both the retrograde fast pathway and the slow pathway but with preservation of anterograde fast pathway conduction was noted in 12 patients. Ablation or modification of the retrograde fast pathway alone or both anterograde and retrograde fast pathway conduction was noted in three patients. Complete AV node block occurred in three patients. Seventy-three patients had no induction of echo beats or tachycardia and 24 patients had induction of a single echo beat after ablation. Follow-up study was performed in 62 patients 76 +/- 18 days after ablation. Thirty-nine patients had no induction of echo beats or tachycardia, 22 had induction of echo beats alone and 1 patient had induction of sustained tachycardia. CONCLUSION: Selective ablation of the slow AV node pathway can be achieved by a simple procedure with a high success rate and few complications.

Adolescent↗
PubMed1993

Radiofrequency ablation therapy in three patients with paroxysmal atrial tachycardia.

Radiofrequency ablation therapy was performed in three patients with paroxysmal atrial tachycardia. There were two females and one male, aged 80, 63, and 75 years, respectively. All three patients had induction of sustained atrial tachycardia. The tachycardia could be terminated by overdrive atrial pacing or atrial premature stimulation; it could also be terminated by intravenous bolus of adenosine triphosphate. In all three patients, there was no fragmented atrial electrograms recorded within the right atrium, and there was no ventriculo-atrial conduction during ventricular pacing. The earliest atrial activation during tachycardia in these three patients was registered, respectively, at a site slightly posterior and inferior to the His-bundle recording site, at the anterior-superior border of Koch's triangle slightly posterior to the His-bundle recording site, and at the mid-lateral aspect of the right atrium over the crista terminalis at the junction of right atrial appendage and sinus venarum. Radiofrequency current was delivered to the site of the earliest atrial activation during tachycardia through a 4-mm tip electrode catheter. It resulted in termination of tachycardia and ablation of the tachycardia focus. Follow-up observation over a period of 16, 15, and 4 months, respectively, in these three patients showed no recurrence of tachycardia. A repeat electrophysiological study was performed 52 and 63 days after ablation in two patients and revealed no induction of atrial tachycardia.

Aged↗
PubMed1993

DNA polymorphisms of apolipoprotein B in the population of Taiwan.

Four apolipoprotein B (apoB) genetic polymorphisms, the AluI, XbaI, MspI and EcoRI restriction fragment length polymorphisms (RFLPs), were analyzed for 162 individuals in Taiwan by polymerase chain reaction. Allele frequency determination revealed that this population has 0.86 AluI- (A-), 0.99 XbaI- (X-), 1.0 MspI+ (M+), and 0.98 EcoRI+ (E+) alleles. Major genotypes were A-/A- (0.75), X-/X- (0.98), M+/M+ (1.0) and E+/E+ (0.96). There were 0.22 A-/A+, 0.02 X-/X+ and 0.04 E+/E- heterozygous genotypes and one minor homozygous A+/A+ (0.03) genotype. The XbaI allele frequency is similar to that found in the Japanese population (XbaI- 0.96), but is significantly different from that in Caucasians (XbaI- 0.31-0.54). Significant differences (p < 0.001) between the Taiwanese and Caucasians were also observed for the AluI, EcoRI and MspI RFLP alleles of the apoB gene. More heterozygous genotypes are observed in Caucasians than in the Taiwanese.

Adult↗
PubMed1993

Coronary artery disease risk predicted by plasma concentrations of high-density lipoprotein cholesterol, apolipoprotein AI, apolipoprotein B, and lipoprotein(a) in a general Chinese population.

We measured lipid and lipoprotein concentrations in blood samples from control subjects and patients with coronary artery disease (CAD) in Taiwan. We found significant differences (P < 0.01) in the concentrations of high-density lipoprotein cholesterol (HDLC), apolipoprotein AI (ApoAI), apolipoprotein B (ApoB), and lipoprotein(a) [Lp(a)]. Concentrations of HDLC < 350 mg/L, ApoAI < 900 mg/L, ApoB > 800 mg/L, and Lp(a) > 200 mg/L occurred, respectively, 2.8, 5.2, 1.7, and 2.3 times more frequently in the patients than in the control group. If one considers HDLC at < 350 mg/L, ApoAI at < 900 mg/L, ApoB at > 800 mg/L, and Lp(a) at > 200 mg/L as separate risk factors for CAD, the ratio of individual patients to control subjects having 4, 3, 2, 1, or 0 risk factors was [symbol: see text] 9.4, 2.1, 0.2, 0.2, respectively. Individuals displaying three or more risk factors were found 15 times more frequently in the CAD group than in the control group. These risk factors may be used clinically for the prediction and prevention of CAD in the general population.

Adult↗
PubMed1992

Nature of dual atrioventricular node pathways and the tachycardia circuit as defined by radiofrequency ablation technique.

OBJECTIVES: A comprehensive electrophysiologic study followed by selective radiofrequency ablation from three sites was performed in patients with atrioventricular (AV) node reentrant tachycardia to better delineate the nature of the tachycardia circuit. BACKGROUND: We postulated that the retrograde fast pathway is the anterior superficial group of transitional cells and the slow pathway is the compact node with its posterior input of transitional cells. Twenty-three consecutive patients were studied. In nine, the atria could be dissociated from the tachycardia by delivery of an atrial extrastimulus during tachycardia. METHODS: Radiofrequency ablation was performed with three approaches. The anterior approach was designed to interrupt the anterior superficial atrial input to the compact node, the posterior approach to interrupt the posterior atrial input to the compact node and the inferior approach to destroy the compact node itself. RESULTS: Selective ablation of the retrograde fast pathway was achieved in seven patients, six with the anterior and one with the inferior approach. Anterograde fast pathway conduction was not affected, whereas retrograde fast pathway conduction was either abolished or markedly depressed. None had induction of echoes or tachycardia after ablation. Selective ablation of the slow pathway was successful in 13 patients, 1 with anterior, 3 with posterior and 9 with inferior approaches. In these 13 patients, both anterograde and retrograde fast pathway conduction were not affected, the dual pathway physiology was abolished and the tachycardia was not inducible after ablation. Ablation of both the retrograde fast pathway and the slow pathway occurred with the inferior approach in three patients. CONCLUSIONS: We conclude that the retrograde fast pathway is likely to be the anterior superficial group of transitional cells, whereas the slow pathway is the compact node and its posterior input of transitional cells. A barrier seems to exist between the atrium and the tachycardia circuit. In a broad view of the AV node structure, the tachycardia circuit is confined to the node.

Atrial Function↗