Association of 1617 C --> T genetic variation in exon 11 of human low-density lipoprotein receptor and plasma lipid concentration.
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Exons↗
Biomedical subjects
M S Wen
Publications and source records attributed to M S Wen.
Variation of P-QRS relation during atrioventricular node reentry tachycardia.
OBJECTIVES: The main objective of this study was to characterize the phenomenon of variation in the P-QRS relation during atrioventricular node reentry tachycardia. BACKGROUND: Variation of P-QRS relation during tachycardia has been observed occasionally in atrioventricular node reentry tachycardia. However, the incidence, the characteristics and the mechanisms of this phenomenon have not been investigated previously. METHODS: Retrospective analysis was performed in 311 consecutive patients with slow-fast form and 108 patients with atypical or multiple form of atrioventricular node reentry tachycardia to examine whether variation of P-QRS relation with changes in AH, HA and AH/HA (A = atria; H = His bundle) ratio occurred during tachycardia. RESULTS: A total of 28 patients, 8 with slow-fast and 20 with atypical or multiple tachycardias, were found to manifest this phenomenon. There were 6 males and 22 females, with an average age of 38+/-16 years. In 10 patients, this phenomenon occurred transiently following electrical induction of the tachycardia. In 15 patients, changes in AH, HA and AH/HA ratio were associated with the occurrence of Wenckebach or 2:1 block proximal to the His bundle (H) recording site without interruption of the tachycardia. In nine patients, three with nonsustained tachycardia and six after administration of adenosine triphosphate, this phenomenon was observed at the termination of the tachycardia. This phenomenon was usually accompanied by a mild lengthening of the tachycardia cycle length. CONCLUSIONS: Variation of P-QRS relation with or without block may occur during atrioventricular node reentry tachycardia, especially in atypical or multiple-form tachycardias. It was postulated that decremental conduction in the distal common pathway, which exists between the distal link of the reentry circuit and the H, is primarily responsible for this phenomenon.
Adenosine Triphosphate↗
Determinants of tachycardia recurrences after radiofrequency ablation of idiopathic ventricular tachycardia.
Clinical and electrophysiologic parameters were analyzed to define the factors potentially related to tachycardia recurrences in 79 patients undergoing successful radiofrequency ablation of idiopathic right or left ventricular tachycardia. It was found that the endocardial activation time at the successful ablation site was the only independent predictor of tachycardia recurrences.
Adolescent↗
Adenosine-sensitive ventricular tachycardia from the anterobasal left ventricle.
OBJECTIVES: This study demonstrates that exercise-provocable tachycardia resembling right ventricular outflow tract tachycardia may originate from the anterobasal left ventricle. BACKGROUND: Reentry is the operative mechanism of idiopathic left ventricular tachycardia, with a QRS complex of right bundle branch block and superior axis that is responsive to verapamil but not adenosine. Whether some mechanism other than reentry is operative in some idiopathic left ventricular tachycardias is unclear. METHODS: In 4 of 53 consecutive patients with idiopathic left ventricular tachycardia, the tachycardia was sensitive to adenosine. These four patients were women 63, 61, 61 and 31 years old and were the subjects of the present study. RESULTS: In all four patients, spontaneous tachycardia was related to exercise or emotional stress. The tachycardia displayed atypical left (one patient) or right (three patients) bundle branch block with an inferior axis and marked variation in cycle length. An intravenous bolus of adenosine triphosphate (10 to 20 mg) terminated tachycardia in all four patients. Tachycardia was terminated or prevented in three patients given intravenous or oral verapamil. Atrial or ventricular incremental or extrastimulus testing induced tachycardia in all four patients (three with, one without isoproterenol infusion). Electrically induced tachycardia also demonstrated marked variation in cycle length, which ranged from 230 to 390 ms. Entrainment was not demonstrable with overdrive pacing from multiple sites. Endocardial mapping during tachycardia revealed that the earliest activations were registered 25, 40, 35 and 50 ms before onset of the QRS complex, respectively, from the anterior aspect of the left ventricle just below the mitral annulus, adjacent to the left ventricular outflow tract. High frequency Purkinje spikes were not recorded at this site. Radiofrequency current delivered to this site successfully ablated the tachycardia in three of the four patients. CONCLUSIONS: Exercise-provocable, catecholamine-mediated, verapamil-responsive, adenosine-sensitive ventricular tachycardia may arise from the anterobasal left ventricle adjacent to the outflow tract.
Adenosine↗
Successful radiofrequency ablation of idiopathic left ventricular tachycardia at a site away from the tachycardia exit.
OBJECTIVES: This study sought to assess the possibility of ablating verapamil-responsive idiopathic left ventricular tachycardia at a site distant from the tachycardia exit and thus to define the tachycardia circuit. BACKGROUND: The nature of the reentry circuit in idiopathic left ventricular tachycardia is unclear. If the circuit is of considerable size, then it should be possible to ablate the tachycardia at a site distant from the exit site. METHODS: Electrophysiologic studies and radiofrequency ablation were performed in 27 consecutive patients with verapamil-responsive idiopathic left ventricular tachycardia. In all 27 patients, the tachycardia exit site was defined as the site where the earliest Purkinje potential was recorded > or = 25 ms before the onset of the QRS complex during the tachycardia and where the pace map QRS complex resembled that during the tachycardia. A potential ablation site other than the exit site was then sought around the midseptum, proximal to the exit site. At such sites the tachycardia could be terminated transiently by pressure applied to the catheter tip, without induction of ventricular ectopic beats. RESULTS: The potential ablation site, other than the tachycardia exit site, was identified in seven male patients (mean [+/-SD] age 31 +/- 12 years, range 13 to 52). Application of the radiofrequency current at this site resulted in termination of the tachycardia within 1 to 5 s (mean 2.9 +/- 1.6), and successful ablation of the tachycardia was achieved in all seven patients (success rate 100%, 95% exact confidence interval 0.5898 to 1). The mean distance between the ablation site and the tachycardia exit site was 3.1 +/- 0.7 cm (range 2.0 to 4.0). A presystolic Purkinje spike was recorded 14 +/- 5 ms (range 8 to 20) before the onset of the QRS complex during the tachycardia. During the follow-up period of 24 +/- 11 months (range 12 to 39), there was no recurrence of tachycardia in these seven patients. CONCLUSIONS: Successful ablation of idiopathic left ventricular tachycardia can be achieved at sites away from the tachycardia exit site in some patients. This finding suggests that the reentry circuit is likely to be of considerable size, encompassing the middle, inferior and lower aspects of the left interventricular septum.
Action Potentials↗
Atypical atrioventricular nodal reentry tachycardia with atrioventricular block mimicking atrial tachycardia: electrophysiologic properties and radiofrequency ablation therapy.
INTRODUCTION: Fast-intermediate form AV nodal reentry tachycardia (AVNRT) sometimes may mimic atrial tachycardia or atrial flutter and render the diagnosis difficult when the tachycardia rate is fast and AV block occurs during tachycardia. METHODS AND RESULTS: A 45-year-old woman with paroxysmal supraventricular tachycardia was referred to this institution. Initially, the tachycardia was thought to be an atrial tachycardia because of: (1) a short cycle length of the tachycardia with 2:1 and Wenckebach AV block; (2) a difference in the atrial activation sequence during tachycardia and during ventricular pacing; and (3) failure of burst ventricular pacing to affect the atrial rate and the atrial activation sequence during tachycardia. An accurate diagnosis of fast-intermediate form AVNRT was subsequently made based on the finding that the tachycardia was induced following delivery of a third ventricular extrastimulus, which showed a sequence of V-A-H and a change on atrial activation sequence of the induced beat. Successful radiofrequency ablation was achieved only after accurate diagnosis of the tachycardia was made. CONCLUSION: Fast-intermediate form AVNRT sometimes may masquerade as atrial tachycardia. Accurate diagnosis is mandatory for successful ablation therapy.
Catheter Ablation↗
Radiofrequency ablation for supraventricular and ventricular tachycardia in young patients.
Radiofrequency ablation therapy was conducted in 86 consecutive children and young patients with a mean age of 14 +/- 3 years (range = 3-18). Fifty-two patients had Wolff-Parkinson-White syndrome, one had re-entry tachycardia incorporating a nodoventricular fiber, 22 had atrioventricular node re-entry tachycardia, two had atrial tachycardia and nine had idiopathic ventricular tachycardia. Radiofrequency ablation was successful in 50 of the 52 patients (96%) with Wolff-Parkinson-White syndrome and the one with nodoventricular fiber. Radiofrequency modification of the atrioventricular node using the inferior approach was successful in eliminating atrioventricular node re-entry tachycardia in 20 of the 22 patients (91%). Radiofrequency ablation in the two patients with atrial tachycardia was unsuccessful. Of the nine patients with idiopathic ventricular tachycardia, eight from the left ventricle and one from the right ventricular outflow tract, eight were successfully ablated (88%). Follow-up over a period ranging from 1 to 46 months (21 +/- 13) revealed a recurrence of tachycardia in seven patients; a late electrophysiological study in 38 patients revealed the induction of tachycardia in 11 patients (seven with accessory pathway-mediated tachycardia, three with atrioventricular node re-entry tachycardia and one with idiopathic ventricular tachycardia). All 11 patients were successfully ablated by a second trial. In conclusion, radiofrequency ablation therapy is effective and safe in pediatric patients with supraventricular and ventricular tachycardia and should be considered as the therapy of choice in this group of patients.
Adolescent↗
Left ventricular fibromuscular band is not a specific substrate for idiopathic left ventricular tachycardia.
BACKGROUND: A fibromuscular band has been detected in patients with idiopathic left ventricular tachycardia, and this band has been suggested to be the anatomic substrate for the arrhythmia. Whether the fibromuscular band is a specific substrate for the tachycardia was systematically evaluated in a large group of consecutive patients with and without idiopathic left ventricular tachycardia. METHODS AND RESULTS: Conventional transthoracic two-dimensional echocardiography and multiplane transesophageal echocardiography were performed in 18 patients with idiopathic left ventricular tachycardia that was responsive to calcium blockers (group 1, tachycardia patients) and 40 patients with paroxysmal supraventricular tachycardia (group 2, control patients). There were 17 men and 1 woman, with a mean age of 29 +/- 11 years, in group 1 patients, and 21 men and 19 women, with a mean age of 42 +/- 12 years, in group 2 patients. The QRS morphology during tachycardia in group 1 patients displayed a pattern of right bundle-branch block with superior axis in 15 patients, indeterminate axis in 2 patients, and inferior axis in 1 patient. Radiofrequency ablation successfully eliminated the tachycardia in all 18 patients; the successful ablation site was located at the inferior apical septum in 11 patients, at the midseptum in 6 patients, and at the anterior lateral wall in 1 patient. Transthoracic echocardiography detected the fibromuscular band in 11 of the 18 patients, whereas multiplane transesophageal echocardiography detected the band in 17 of 18 patients. The fibromuscular band extended from the interventricular septum to the apex of the left ventricle. In group 2 patients, transthoracic echocardiography detected the fibromuscular band in 22 and multiplane transesophageal echocardiography detected the band in 35 of the 40 patients. The presence of a fibromuscular band in these two groups of patients was not statistically different. CONCLUSIONS: The presence of a left ventricular fibromuscular band is not a specific anatomic substrate for idiopathic left ventricular tachycardia.
Adult↗
Catheter-induced atrioventricular nodal block during radiofrequency ablation.
This study examined the incidence and significance of catheter-induced atrioventricular nodal block (AVNB) during a radiofrequency ablation procedure that uses stiff large-tip steerable ablation catheters. AVNB was noted in 10 (1.6%) of 613 consecutive patients undergoing radiofrequency ablation therapy for atrioventricular nodal (AVN) reentrant tachycardia (592 patients) or atrioventricular reentry tachycardia incorporating a midseptal accessory pathway (21 patients). Of these 10 patients, 9 underwent AVN modification for AVN reentrant tachycardia and 1 for ablation of a midseptal accessory pathway. One patient had two episodes of AVNB during two sessions undertaken because of recurrence of tachycardia. No patient had a preexisting conduction defect before the study. In all 10 patients, AVNB was transient, and it lasted for a mean of 9.1 +/- 19 minutes. It occurred during positioning of the ablation catheter in the junctional area before (8 patients) or after (2 patients) the start of radiofrequency current applications. Complete AVNB was noted on six occasions, second-degree AVNB on four occasions, and first-degree AVNB on one occasion. All blocks were associated with narrow QRS ventricular beats and with a site of block proximal to the His bundle. The mean ventricular heart rate during AVNB was 60 +/- 23 beats/min. Two patients had transient asystole, with one having loss of consciousness. No patient required special treatment for heart block. One-to-one conduction resumed after repositioning of the catheters, and the subsequent ablation procedure was successfully completed in 8 of the 10 patients. During a follow-up of 20 +/- 12 months, none of the patients had severe dizziness or syncope, and none required implantation of a permanent pacemaker. In conclusion, transient AVNB due to mechanical injury occurs during positioning of a stiff large-tip steerable ablation catheter in the junctional area. Delivery of radiofrequency current to the site that provokes catheter-induced AVNB should be avoided.
Adolescent↗
Effective therapy with transthoracic video-assisted endoscopic coagulation of the left stellate ganglion and upper sympathetic trunk in congenital long-QT syndrome.
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Adult↗
Radiofrequency ablation therapy of the posteroseptal accessory pathway.
Among 652 patients with Wolff-Parkinson-White syndrome who underwent radiofrequency ablation in this laboratory, 139 (21%) were found to have a total of 146 posteroseptal accessory pathways. Ablation was conducted by the regular transvenous or transaortic approach; ablation from cardiac venous structures was used only if regular approaches were unsuccessful. Of the 146 posteroseptal accessory pathways, 94 were successfully ablated from the left posteroseptal region and 45 from the right posteroseptal region. In 3, successful ablation of the accessory pathway required delivery of the current to the proximal coronary sinus, and in 1 it required delivery of the current to both the atrial and ventricular aspects of the tricuspid valve at the right posteroseptum. Thus, the accessory pathway was successfully ablated in 143 (98%) of 146 instances or in 136 (98%) patients. In 3 patients, ablation was unsuccessful despite delivery of current to the left posteroseptum, the right posteroseptum, the proximal coronary sinus, and the middle cardiac vein. Seventy-seven (57%) patients with an initial success, including 9 patients with resumed preexcitation or recurrence of paipitations, underwent a follow-up electro-physiologic study 90 +/- 72 days after ablation. Of these 9 patients, the initial successful ablation site was the right posteroseptum in 7 and the left posteroseptum in 2. The accessory pathways were ablated successfully by subsequent trials in 8 patients, whereas in 1 the accessory pathway was severely damaged. Thus radiofrequency ablation of posteroseptal accessory pathways can be achieved by the regular transvenous or transaortic approach; delivery of current to the coronary sinus or middle cardiac vein is unnecessary in most patients.
Adult↗
Apolipoprotein B 3' hypervariable repeat genotype: association with plasma lipid concentration, coronary artery disease, and other restriction fragment polymorphisms.
Apolipoprotein B gene 3' variable number tandem repeat (VNTR) and related regions were amplified by PCR and analyzed by agarose gel electrophoresis. Eighteen VNTR alleles (VNTR25, 26, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 58, 60) and 45 genotypes were observed in 477 Taiwanese subjects. The VNTR35 allele and genotype VNTR35/35 were observed most frequently in this population. The polymorphism information content was 0.62. Some minor alleles, such as VNTR25 and 60, were found only in coronary artery disease (CAD) and stroke patients in our sampling, and no statistically significant difference was observed in VNTR allelic frequency between control and CAD or stroke patients. Significant differences in allelic distribution of some VNTR alleles were observed between our normal Taiwanese population and a Caucasian group studied by others. VNTR43-47 and AluI+ (coding Ala591) restriction fragment length polymorphism (RFLP) as well as VNTR49-60 and EcoRI- (coding Lys4154) RFLP were found to be highly coinherited. No apparent association between the VNTR genotype and plasma lipid concentration was observed; however, for the same genotype, the CAD and stroke patients frequently showed higher lipoprotein(a) and lower HDL cholesterol concentrations than the control group.
Alleles↗
Retrograde atrio-His bundle dissociation as a sign indicative of retrograde accessory pathway conduction.
Electrophysiologic study and radiofrequency ablation therapy were performed in a 36-year-old male with Wolff-Parkinson-White syndrome and Ebstein's anomaly. The study disclosed the presence of a posteroseptal accessory pathway and dual atrioventricular (AV) nodal pathways. Retrograde atrio-His bundle (A-H) dissociation was noted during rapid ventricular pacing, in which the atria were activated by retrograde impulse from the accessory pathway with a fixed ventriculo-atrial (VA) interval while the retrograde His bundle potential was visible during the diastolic isoelectric period due to the occurrence of Wenckebach periodicity within the His-Purkinje system. This phenomenon is a useful sign for rapid recognition of the accessory pathway conduction.
Adult↗
Multiplane transesophageal echocardiography in the diagnosis of congenital coronary artery fistula.
The purpose of this study was to examine the advantages of multiplane transesophageal echocardiography in the diagnosis of congenital coronary artery fistula, specifically in depicting the origin, the course, and the drainage site. Seven consecutive patients ranging in age from 20 to 72 years with a suspected coronary artery fistula underwent conventional transthoracic and multiplane transesophageal echocardiographic studies between March 1993 and July 1994. When a coronary artery fistula was noted, the origin, the course, and the drainage site were carefully searched for. All patients then underwent a cardiac catheterization with the performance of coronary angiography. A large right coronary artery fistula was detected in three patients; one of them had a drainage to the posterior left ventricle, one to the lateral right ventricle, and the other to the medial aspect of the right ventricle just below the insertion of the septal leaflet of the tricuspid valve. A small coronary artery fistula arising from the left coronary artery was noted in four patients, two from the left anterior descending artery and the other two from the left circumflex artery. Three of these four patients had a drainage to the main pulmonary artery and one to the left ventricle. The drainage site was clearly depicted in all seven patients, whereas the origin and the course were precisely defined in five patients by using multiplane transesophageal echocardiographic examination. The multiplane transesophageal echocardiography provides a panoramic view of the coronary artery and the fistulous vessel with a precise definition of the origin, the course, and the drainage site of the fistula. Therefore it is the noninvasive diagnostic mode of choice.
Adult↗
Progression to complete atrioventricular block in a patient with bundle branch re-entry tachycardia.
A 38-year-old man with no significant structural heart disease suffered from one episode of wide QRS tachycardia. The electrocardiogram showed a PR interval of 0.20 second and a QRS duration of 0.10 second. His bundle recording revealed an HV interval of 90-100 ms. The tachycardia was inducible with programmed stimulation and displayed a QRS morphology of complete left bundle branch block. It was characterized by an atrioventricular dissociation, a cycle length of 280 ms, and an H deflection preceding each QRS complex. Pacing from the right ventricular apex at a cycle length of 270 ms entrained the tachycardia, while at a cycle length of 260 ms, the tachycardia was terminated. Four years later, the patient presented with complete atrioventricular block with a wide QRS escape rhythm. An electrophysiologic study conducted while he was in 1:1 atrioventricular conduction showed an HV interval of 100 ms. Second-degree infrahisian block developed at an atrial paced cycle length of 700 ms. There was no induction of tachycardia with programmed stimulation before or after isoproterenol. The patient was treated with an implantation of a permanent pacemaker.
Adult↗
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↗
Effects of adenosine on paroxysmal atrial tachycardia.
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Adenosine Triphosphate↗
The effects of adenosine on idiopathic ventricular tachycardia.
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Adenosine Triphosphate↗