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Jiunn-Lee Lin

Publications and source records attributed to Jiunn-Lee Lin.

34 records · Page 2Linked to original sources
PubMed2004

Functional genomic study on atrial fibrillation using cDNA microarray and two-dimensional protein electrophoresis techniques and identification of the myosin regulatory light chain isoform reprogramming in atrial fibrillation.

INTRODUCTION: Functional and structural changes of atrial tissue occur during the natural course of atrial fibrillation (AF), and these changes may contribute to further AF. We investigated the changes in AF tissue using cDNA microarray and two-dimensional protein electrophoresis techniques. METHODS AND RESULTS: We established a porcine model of AF by rapid right atrial appendage pacing at a rate of 600/min. Atrial tissue was obtained after rapid atrial depolarization for 6 weeks. Microarrays containing 6,035 cDNA clones were used to evaluate the alterations of mRNA. Two-dimensional protein electrophoresis was performed to compare protein patterns. In cDNA microarray studies, we identified 387 genes with significant change in the left atrium and 81 genes in the right atrium. Among the genes, the ventricular isoform of the myosin regulatory light chain (MLC-2V) showed the greatest fold of change (9.4 and 7.3 in the left and right atrium, respectively). In protein electrophoresis, the expression levels of three protein spots spanning from 18 to 20 kDa in the acidic region (PI 4.5-5.0) were specifically elevated in the AF group. Interestingly, through tandem mass spectrometric analysis, these three spots were identified as MLC-2V. Thus, MLC-2V expression at the mRNA and protein levels corresponded well, and both indicated a significant increase in AF. CONCLUSION: Both cDNA microarray and two-dimensional polyacrylamide protein electrophoresis studies revealed characteristic changes in AF tissue. We demonstrated the reprogramming of myosin regulatory light chain isoform composition, with a significant increase of its ventricular isoform (MLC-2V).

Animals↗
PubMed2004

Use of double-potential barrier to identify functional isthmus at the cavotricuspid isthmus for facilitating catheter ablation of isthmus-dependent atrial flutter.

INTRODUCTION: The aim of the study was to identify an alternative target for more effective radiofrequency catheter ablation (RFCA) of isthmus-dependent atrial flutter (AFL). METHODS AND RESULTS: We hypothesized that a functional isthmus formed by preexisting double potential barrier at the cavotricuspid isthmus (CTI) could serve as a new target site for facilitating RFCA of AFL. Forty-three consecutive patients with recurrent isthmus-dependent AFL were studied using three-dimensional navigated magnetic mapping and ablation technique. Twenty patients (47%, group A) were shown to have a narrower functional channel at the CTI (functional isthmus). The remaining 23 patients did not have this feature (53%, group B). In group A, double potentials were clustered near the border of the inferior vena cava (IVC) of the CTI and served as a functional channel along the tricuspid annulus (TA). The interspike interval of double potentials was 87 +/- 26 ms near the IVC border and 45 +/- 17 ms (P < 0.0001) near the TA border of CTI. RFCA targeting at the functional isthmus in group A resulted in interruption of bidirectional transisthmus conduction with fewer radiofrequency pulses (6.7 +/- 4.7 in group A vs 21.1 +/- 17.1 pulses in group B, P < 0.001), shorter ablation line (11.6 +/- 4.0 mm vs 37.8 +/- 7.2 mm, P < 0.0001) with no arrhythmia recurrence. These functional isthmuses were found to be located at the lateral third of CTI in 12 patients, middle third in 7, and medial third in 1. This finding is different from that obtained by the conventional method in group B (lateral in 5, middle in 16, medial in 2, P < 0.038). CONCLUSION: In our study, a functional, rather than anatomic, isthmus formed by preexisting double-potential barrier at the CTI was identified in 47% of patients with isthmus-dependent AFL. It is a useful guide to facilitate RFCA of isthmus-dependent AFL.

Atrial Flutter↗
PubMed2004

Activation of the calcineurin-nuclear factor of activated T-cell signal transduction pathway in atrial fibrillation.

STUDY OBJECTIVES: The calcineurin-nuclear factor of activated T-cell (NFAT) signal transduction pathway regulates the expression of a plethora of genes in the myocardium. Cytosolic calcium overloading occurs in atrial fibrillation (AF), and this fulfills the condition needed for activation of this pathway. We therefore investigated the NFAT pathway in atrial tissue in a porcine model of AF. METHODS AND RESULTS: AF was induced in eight adult pigs by rapid atrial pacing. Investigations on the calcineurin and NFAT pathway were performed on transmural left atrial tissue obtained 6 weeks after implantation of the pacemaker (pacing for 4 weeks, and AF without pacing for 2 weeks). In the AF group, the left atrial dimension increased significantly (26 +/- 4 mm vs 31 +/- 4 mm, respectively, p < 0.05 [mean +/- SD]). Calcineurin enzyme activity increased significantly in pigs with AF (n = 8) when compared to control pigs (n = 6) [0.143 +/- 0.034 vs 0.038 +/- 0.063 mmol PO(4)(-) released, p < 0.01]. We found that both NFAT-c3 and NFAT-c4, the downstream effectors of calcineurin, increased significantly in the nuclei in AF tissue using immunoblotting. Translocation of NFAT-c3 and NFAT-c4 into the nuclei was also demonstrated in AF tissue microsections using immunohistochemistry. The electrophoresis mobility shift assay further demonstrated that nuclear extracts from AF tissue had a significantly larger binding capacity for NFAT-specific oligonucleotide probes. CONCLUSIONS: Our results demonstrate that calcineurin activity was increased in AF with subsequent NFAT-c3 and NFAT-c4 translocation into the nucleus. Activation of this signal transduction pathway may play an important role in the pathogenesis of AF.

Animals↗
PubMed2004

Exercise-provoked bidirectional ventricular tachycardia in a young woman.

Exercise-induced ventricular tachycardia (VT) is rare in children and young adults without structural heart disease. Catecholaminergic polymorphic VT (CPVT) is among the possible causes and carries a poor prognosis. The QRS morphology of CPVT can be bidirectional, polymorphic or even ventricular fibrillation. We report a case of CPVT initially presenting as sudden collapse in an 18-year-old Taiwanese woman. Family history was negative for arrhythmias and sudden death. Laboratory analyses, transthoracic echocardiography, magnetic resonance imaging, electrophysiological study including procainamide and isoproterenol test were all negative. Bidirectional VT was induced by treadmill exercise test. She responded well to beta-blocker therapy. Some cases of CPVT are sporadic and some occur in patients with a family history. The treatment of choice for this disease is beta-blocker and implantation of an internal cardioverter defibrillator.

Adolescent↗
PubMed2003

Usefulness of ST-segment elevation in lead aVR during tachycardia for determining the mechanism of narrow QRS complex tachycardia.

In the present study, we analyzed ST-segment elevation in lead aVR during tachycardia to differentiate the narrow QRS complex tachycardia. A total of 338 12-lead electrocardiograms during narrow QRS complex tachycardia were analyzed. Each patient underwent a complete electrophysiologic study. There were 161 episodes of atrioventricular nodal reentrant tachycardia (AVNRT), 165 episodes of atrioventricular reciprocating tachycardia (AVRT), and 12 episodes of atrial tachycardia (AT). The prevalence of aVR ST-segment elevation was 71% for AVRT, 31% for AVNRT, and 16% for AT. For ST-T changes in different leads, logistic regression analysis showed aVR ST-segment elevation was the only significant factor to differentiate the types of narrow QRS complex tachycardia (p<0.001 for AVRT and AVNRT; p=0.02 for AVRT and AT). The sensitivity, specificity, and accuracy of aVR ST-segment elevation to differentiate AVRT from AVNRT and AT were 71%, 70%, and 70%, respectively. Among 117 episodes of AVRT with aVR ST-segment elevation, there were 76 (65%) left side, 23 (20%) right side, 14 (12%) posterior septal, and 4 (3%) antero- and mid-septal accessory pathways (p=0.002). In conclusion, aVR ST-segment elevation during narrow QRS complex tachycardia favors the atrioventricular reentry through an accessory pathway as the mechanism of the tachycardia.

Adult↗
PubMed2003

Distinct clinical features in the recipients of the implantable cardioverter defibrillator in Taiwan: a multicenter registry study.

Little information about the ICD is available from the Asian Pacific region. The purpose of this study was to characterize the clinical features in ICD patients in Taiwan and to compare these features with those in patients in the Western populations, mainly the Canadian Implantable Defibrillator Study (CIDS), the Antiarrhythmics versus Implantable Defibrillator (AVID) trial, and the Cardiac Arrest Study Hamburg (CASH) trial. From February 1995 to October 2001, 101 ICDs were implanted in 92 patients (78 [84%] men) in 12 hospitals. Clinical presentations included sudden cardiac death due to VF/VT in 35 (38%) patients, syncopal VT in 25 (27%), drug refractory nonsyncopal VT in 27 (29%), and unexplained syncope with inducible sustained VT/VF in 5 (6%). The mean age was significantly younger than that in CIDS or AVID (59 +/- 16 vs 63 +/- 9 years in CIDS, P = 0.02; vs 65 +/- 11 years in AVID, P < 0.001), but was comparable to that in CASH (59 +/- 16 vs 58 +/- 11 years in CASH, P = 0.75). The mean LVEF was significantly higher than that in CIDS or AVID (48 +/- 19% vs 34 +/- 15% in CIDS, P < 0.001; vs 32 +/- 13% in AVID, P < 0.001), but was comparable to that in CASH (48 +/- 19 vs 46 +/- 19% in CIDS, P = 0.83). The ICD patients in the current study also showed a higher incidence of normal heart (23 vs 4% in CIDS, P < 0.001; vs 3% in AVID, P < 0.001; vs 9% in CASH, P < 0.001) and cardiomyopathy (41% vs 10% in CIDS, P < 0.001; vs 15% in AVID, P < 0.001; vs 11% in CASH, P < 0.001), but a lower incidence of coronary artery disease (29% vs 83% in CIDS, P < 0.001; vs 82% in AVID, P < 0.001; vs 73% in CASH, P < 0.001). During a mean follow-up of 28 +/- 24 months, 13 (14%) patients died. Older age was the only factor associated with poorer survival after ICD implantation. Forty-seven (51%) patients received appropriate ICD discharges during follow-up. History of prior myocardial infarction was the only factor associated with an earlier first appropriate ICD discharge and LVEF < 0.35 the only factor associated with subsequent poorer survival after the first ICD discharge. In conclusion, this study demonstrated many distinct clinical features in our ICD population that were different from those in the Western populations.

Aged↗
PubMed2003

Characteristic P wave morphology in patients undergoing the atrial compartment operation for chronic atrial fibrillation with mitral valve disease.

The P wave in the surface ECG represents atrial electrical activation and may be altered in certain pathological conditions. Atrial compartment operation has been used to convert chronic AF to sinus rhythm. However, this procedure may result in changes of impulse conduction in various atrial compartments and alters the P wave morphology. This study sought to elucidate the P wave changes after the atrial compartment operation for AF. Fifteen patients undergoing the atrial compartment operation for chronic AF were studied. In the operation, the atrium was divided into three compartments, namely the left atrium, the atrial septum including sinus and AV nodes, and the right atrial compartment. The anatomic connection between adjacent compartments were preserved at the posterior lower margin of incisions. The surface lead P waves were correlated with intracardiac recording and stimulation in various atrial compartments. Fifteen age- and sex-matched control patients without structural heart diseases were compared. The results showed that patients undergoing the atrial compartment operation had a prolonged P wave duration (190 +/- 27 v s95 +/- 14 ms, P < 0.001), a prolonged PR interval (207 +/- 23 vs 155 +/- 20 ms, P < 0.001), and a shortened PR segment (17 +/- 19 vs 60 +/- 17 ms, P < 0.001). The increase in P wave duration was primarily due to a conduction delay from the sinus node to the other atrial compartments as the conduction time from the high right atrium to the right atrial appendage was 132 +/- 57 ms(vs 21 +/- 6 ms for control,P < 0.001), and the conduction time from the high right atrium to the distal coronary sinus was 140 +/- 55 ms(vs 70 +/- 15 ms, P < 0.001). However, the conduction from the high right atrium to the low septal right atrium, which were located in the same compartment, was not impaired. Also, the conduction in the AV node and His-Purkinje system were not impaired. The mean axis of P waves varied greatly, but was not statistically different from that of the control group (60 +/- 48 degrees vs 52 +/- 18 degrees,P > 0.05). Although the patients undergoing atrial compartment operation had a larger left atrial size, their P wave amplitude was smaller (1.0 +/- 0.3 vs 1.3 +/- 0.3 mm, P < 0.01), and an increased negative terminal force in V1 was not seen (0.02 +/- 0.02 vs 0.02 +/- 0.01 mm/s, P > 0.05). Alteration in P wave morphology was seen in 14 patients. All the P waves showed a biphasic configuration with an initial positive and a terminal slurred negative deflection in leads II, III, and aVF. The terminal components represented the activation of right atrial appendage in 5 patients, the left atrium in 1, and the combined activation of right atrial appendage and the left atrium in 8 patients. The P wave morphology suggested that activation of both the right atrial appendage and the left atrial compartments proceeded in a caudocranial direction as a result of the atrial incisions. In conclusion, atrial compartment operation altered the conduction time and direction in the atria and resulted in characteristic P wave changes.

Adult↗
PubMed2003

Electrophysiological mapping and histological examinations of the swine atrium with sustained (> or =24 h) atrial fibrillation: a suitable animal model for studying human atrial fibrillation.

OBJECTIVES: Interventional elimination of chronic persistent atrial fibrillation (AFib) remains difficult. An animal model mimicking the clinical situation is important. METHODS AND RESULTS: Twenty-five adult pigs were implanted with a high-speed atrial pacemaker. After continuous pacing at 600 bpm for 6 weeks, 20 (91%) of the 22 survivals developed sustained AFib lasting for at least 24 h. Epicardial dense mapping revealed multiple coexisting reentrant wavelets in the left and the right atrium (LA and RA, respectively; 10.6 +/- 2.9 vs. 7.6 +/- 2.4 wavelets/cm(2)/s; p < 0.002). The mean local A-A intervals were 87.2 +/- 14.6 ms in the LA and 103.3 +/- 19.0 ms in the RA (p < 0.0002). Acute termination of sustained AFib was successful in 3 of the 5 pigs by propafenone, but in none of the 6 by dl-sotalol. Epicardial cryothermal ablation failed to terminate any AFib by compartmentalization of the RA free wall alone (4 pigs) or together with the LA appendage (4 pigs). Electron microscopic examination demonstrated diffuse perinuclear myolysis, myofibrillar fragmentation and mitochondrial crystal disruption in the atrium. CONCLUSIONS: Pacing-induced sustained AFib (> or =24 h) in adult pigs is a feasible and efficient animal model with electrophysiological and histological characteristics closely similar to those seen in humans.

Animals↗
PubMed2003

Characteristics of Chinese patients with symptomatic Brugada syndrome in Taiwan.

Since 1992, the Brugada syndrome has been increasingly recognized worldwide, although its incidence and distribution remain unclear. In Asia, several cases have been reported in Japan, Thailand, Singapore, and Vietnam. However, little information is available from the Chinese population. Since June 1997, we have identified 10 patients with the diagnosis of the Brugada syndrome from six hospitals in Taiwan. All patients were male with the mean age of 46 +/- 7 years (range 36-61). They all had a normal chemistry profile, coronary angiography and echocardiography. Clinical presentations varied from seizure and syncope to sudden cardiac death. MRI and ultrafast CT of the heart did not show any abnormalities. Sustained ventricular tachycardia/ventricular fibrillation (VF) was induced in 7 of 8 patients who underwent an electrophysiologic study. The pharmacological provocation test was positive in 4 of 5 patients. One of the 4 patients who had a genetic study showed SCN5A gene mutation. An implantable cardioverter defibrillator (ICD) was implanted in 8 patients. During a mean follow-up of 29 +/- 17 months (range 2-54), 3 of 8 patients who had an ICD received appropriate ICD discharges after implantation. These 3 patients who were subsequently treated with antiarrhythmic agents have had no further recurrent ICD discharges. Two patients who refused ICD implantation are alive and well without taking antiarrhythmic agents. Our study showed that the clinical characteristics of our patients are similar to those described in the literature and that ICD is an effective treatment modality for patients with recurrent VF. However, antiarrhythmic agents may be beneficial for suppressing arrhythmia recurrences in selected patients.

Adult↗
PubMed2003

Molecular genetic studies in atrial fibrillation.

Atrial fibrillation is a complex disease. Its etiologies are diverse and genetic factors may also contribute to this disease. With the advent of modern molecular biology technology, it is now possible to explore the genetic components in the pathogenesis of atrial fibrillation. Past molecular genetic studies on atrial fibrillation in the literature can be divided into linkage analysis studies and association studies. The subjects for linkage analysis studies are pedigrees of probands with Mendelian hereditary atrial fibrillation. The first locus identified for autosomal dominant atrial fibrillation locates at 10q22-q24. However, the exact gene is still unknown. Another linkage analysis study in Chinese revealed that LQT1 gene (I(Ks) alpha-subunit) was the responsible gene. A missense mutation in the I(Ks) alpha-subunit results in a gain of function, which is important in causing atrial fibrillation. The third known locus for familial atrial fibrillation locates at 6q14-16. The responsible gene remains still unknown. The other type of studies takes the case-control design (association studies) and the subjects have multigenic atrial fibrillation. In a study in a Japanese population, it was reported that the angiotensin-converting enzyme insertion/deletion polymorphism was not associated with atrial fibrillation. On the other hand, researchers in Taiwan reported that a nonsynonymous single nucleotide polymorphism of the LQT5 gene (I(Ks) beta-subunit) is associated with atrial fibrillation. In summary, there is growing evidence showing that genetic factors are important in the pathogenesis of atrial fibrillation. We expect that more genes responsible for or contributing to atrial fibrillation will be identified in the future and these will elucidate the molecular mechanisms of atrial fibrillation.

Animals↗
PubMed2003

Atrial fibrillation is associated with accumulation of aging-related common type mitochondrial DNA deletion mutation in human atrial tissue.

STUDY OBJECTIVE: Accumulation of somatic mutations of mitochondrial DNA (mtDNA) contributes to the aging process and progressive organ dysfunction. We investigated the mitochondrial DNA with 4977-base-pair mtDNA deletion mutation (mtDNA(4977)) in human atrial tissue and correlated the amount of mtDNA(4977) to clinical atrial fibrillation (AF). METHODS AND RESULTS: Atrial tissue from the right atrial appendage was obtained in 88 patients during open-heart surgery (22 children/adolescents and 66 adults). The amount of mtDNA(4977) was measured using a nested polymerase chain reaction protocol and normalized to wild-type mtDNA. We found that the mtDNA(4977) was absent in all 22 pediatric/adolescent patients. In the adult group, the relative amount of mtDNA(4977) was significantly higher in patients with AF than in patients without AF (0.55 +/- 0.26 vs 0.35 +/- 0.29, p < 0.007) [mean +/- SD]. The amount of mtDNA(4977) was also positively associated with age (r = 0.29, p < 0.01). Left and right atrial pressures, left atrial dimension, hypertension, and cardiac diagnosis did not influence the amount of mtDNA(4977) significantly. Further multivariate analysis showed that both aging and AF contributed independently to the accumulation of mtDNA(4977). CONCLUSION: AF is associated with an increase of mtDNA(4977). This change is similar to the aging process of atrial tissue and might contribute to atrial dysfunction in AF.

Adolescent↗
PubMed2002

Tight mechanism correlation between heart rate turbulence and baroreflex sensitivity: sequential autonomic blockade analysis.

INTRODUCTION: Heart rate turbulence is a powerful de novo risk predictor for patients surviving acute myocardial infarction. However, little is known about its underlying physiologic mechanism. METHODS AND RESULTS: Hypothesizing that heart rate turbulence is barorceptor reflex related, we studied heart rate and blood pressure fluctuations at rest and after systematically introduced ventricular premature beats in 16 patients without structural heart disease (10 men and 6 women; mean age 45 +/- 17 years) before and after sequential sympathetic (esmolol 4-mg bolus followed by 120 microg/kg/min intravenously), parasympathetic (atropine 0.04 mg/kg intravenously), and combined autonomic blockade (esmolol plus atropine). Turbulence onset (%) and turbulence slope (msec/beat) were averaged from 10 respective ventricular premature beats. Spontaneous baroreflex sensitivity (msec/mmHg) was calculated from 5 minutes of sinus rhythm recording. The results showed that turbulence slope decreased after atropine (0.71 +/- 0.50 msec/beat vs 5.17 +/- 3.96 msec/beat at baseline; P < 0.01) and combined autonomic blockade (1.23 +/- 1.02 msec/beat; P < 0.01) but was unchanged after esmolol (4.53 +/- 3.30 msec/beat; P > 0.05). Turbulence onset increased after atropine (0.32% +/- 0.35% vs -0.45 +/- 0.94 at baseline; P < 0.05) and combined sympathetic and parasympathetic blockade (0.58% +/- 0.86%; P < 0.05) but was unchanged after esmolol (-0.62% +/- 1.33%; P > 0.05). Turbulence slope was positively correlated with baroreflex sensitivity at baseline (r = 0.78, P < 0.01) and after esmolol (r = 0.8, P < 0.01), but dissociated after atropine (r = 0.16, P > 0.05) and combined autonomic blockade (r = 0.31, P > 0.05). Turbulence onset was negatively correlated with baroreflex sensitivity at baseline (r = -0.61, P < 0.05), after esmolol (r = -0.80, P < 0.01), and after atropine (r = -0.53, P < 0.05). CONCLUSION: Heart rate turbulence of turbulence onset and turbulence slope is critically vagal dependent and highly correlated with spontaneous baroreflex sensitivity, which underscores its clinical importance in cardiovascular risk stratification.

Adult↗
PubMed2002

Association of the human minK gene 38G allele with atrial fibrillation: evidence of possible genetic control on the pathogenesis of atrial fibrillation.

BACKGROUND: Human minK protein is the beta-subunit of I(Ks) potassium channel and plays an important role in cardiac cellular electrophysiology. We investigated the association between human atrial fibrillation and the polymorphism of minK gene (38G or 38S) with a case-control study. METHODS: We included 108 patients with atrial fibrillation and 108 control subjects. The case patients and control subjects were matched regarding age, sex, presence of valvular heart disease, and presence of left ventricular dysfunction. The genotype of minK was determined with polymerase chain reaction and restriction fragment analysis. RESULTS: The results showed an association between the minK 38G allele and atrial fibrillation. The odds ratios for atrial fibrillation in patients with 1 and 2 minK 38G alleles were 2.16 (95% CI 0.81-5.74) and 3.58 (95% CI 1.38-9.27), respectively, when compared with patients without minK 38G allele. In a logistic regression model, the odds ratio for atrial fibrillation was 1.80 (95% CI 1.20-2.71, P <.0046) for patients with 1 more minK 38G allele. CONCLUSION: We report the association between the minK 38G allele and clinical atrial fibrillation. Our findings suggest possible genetic control on the pathogenesis of atrial fibrillation.

Alleles↗
PubMed2002

Predictors of clinical recurrence after successful electrical cardioversion of chronic persistent atrial fibrillation: clinical and electrophysiological observations.

Recurrence of atrial fibrillation (AF) after electrical cardioversion of chronic AF is not uncommon. However, it remains unclear which parameter(s) predict clinical recurrence. To assess the potential predictors of clinical recurrence after successful electrical cardioversion, we analyzed clinical, echocardiographic and electrophysiologic parameters in 36 patients (age 63 +/- 11 years; 26 males, 10 females) with chronic persistent AF lasting more than 3 months. The dimensions of the left atrium and left ventricular end diastole and end systole were measured by echocardiography. The P wave characteristics from the surface 12-lead electrocardiogram (ECG) were studied in sinus rhythm. Atrial local activations were studied by biatrial basket electrode mapping in AF. With a mean of 7 +/- 2 months of follow-up, 17 (47%) patients had AF recurrence despite multiple antiarrhythmic drug therapy. None of the clinical or echocardiographic parameters were relevant to the recurrence. However, among the surface ECG and intraatrial electrophysiological parameters, the mean P wave duration was the only independent predictor of the risk of clinical recurrence after successful electrical cardioversion. The sensitivity and predictive accuracy of recurrence were 82 and 70%, respectively, when the mean P wave duration was more than 125 ms.

Adult↗