• Journal of Chest Surgery
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• v.50 no.3
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• pp.163-170
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• 2017

Background: The absence of atrial contraction (AC) after the maze procedure has been reported to cause subsequent annular dilatation and to increase the risk of embolic stroke. We hypothesized that the lack of AC could increase the risk of permanent pacemaker (PPM) implantation in patients undergoing the maze procedure. Methods: In 376 consecutive patients who had undergone a cryo-maze procedure and combined valve operation, recovery of AC was assessed at baseline and at immediate (${\leq}2$ weeks), early (${\leq}1$ year, $4.6{\pm}3.8$ months), and late (>1 year, $3.5{\pm}1.1$ years) postoperative stages. Results: With a median follow-up of 53 months, 10 patients underwent PPM implantation. Seven PPM implants were for sinus node dysfunction (pauses of $9.6{\pm}2.4$ seconds), one was for marked sinus bradycardia, and two were for advanced/complete atrioventricular block. The median (interquartile range) time to PPM implantation was 13.8 (0.5-68.2) months. Our time-varying covariate Cox models showed that the absence of AC was a risk factor for PPM implantation (hazard ratio, 11.92; 95% confidence interval, 2.52 to 56.45; p=0.002). Conclusion: The absence of AC may be associated with a subsequent risk of PPM implantation.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.112-112
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• 2003

Voltage-gated $K^{+}$ (Kv) channels represent a structurally and functionally diverse group of membrane proteins. These channels play an important role in determining the length of the cardiac action potential and are the targets for antiarrhythmic drugs. Many $K^{+}$ channel genes have been cloned from human myocardium and functionally contribute to its electrical activity. One of these channels, Kv1.5, is one of the more cardiovascular-specific $K^{+}$ channel isoforms identified to date and forms the molecular basis for an ultra-rapid delayed rectifier $K^{＋}$ current found in human atrium. Thus, the blocker of hKv1.5 is expected to be an ideal antiarrhythmic drug for atrial fibrillation. Chelidonine was isolated from Chelidonium majus L. We examined the effect of chelidonine on the hKv1.5 current expressed in Ltk-cells using whole cell mode of patch clamp techniques. Chelidonine selectively inhibited the hKv1.5 current expressed in Ltk-cells in a concentration-dependent manner, whereas did not affect the HERG current expressed in HEK-293 cells. Additionally, chelidonine reduced the tail current amplitude recorded at -50 mV after 250 ms depolarizing pulses to +60 mV, and slowed the deactivation time course resulting in a 'crossover' phenomenon when the tail currents recorded under control conditions and in the presence of chelidonine were superimposed. We found that chelidonine also inhibited the $K^{+}$ current in isolated human atrial myocytes where hKv1.5 channels were predominantly expressed. Furthermore, we examined the effects of chelidonine on the action potentials in rabbit hearts using conventional microelectrode technique. Chelidonine prolonged the action potential durations (APD) of atrial, ventricular myocytes and Purkinje fibers in a dose-dependent manner. However, the effect of chelidonine on atrial APD was frequency-dependent whereas the effect of chelidonine on the APDs of ventricular myocytes and Purkinje fibers was not frequency- dependent. Also, the selective action of chelidonine on heart was more potent than dofetilide, $K^{+}$ channel blocker.

• Journal of Genetic Medicine
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• v.15 no.1
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• pp.20-23
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• 2018

Point mutations in the human cardiac homeobox gene NKX2.5 are associated with familial atrial septal defect (ASD), atrioventricular (AV) conduction disturbance, as well as sudden cardiac death. To date, more than 60 NKX2.5 mutations have been documented, but there are no reports in Korea. We are reporting the first Korean family with ASD and AV block associated with a novel mutation in the NKX2.5 coding region. A 9-year-old boy presented with a slow and irregular pulse, and was diagnosed with secundum ASD and first degree AV block. The boy's father, who had a history of ASD correction surgery, presented with second degree AV block and atrial fibrillation. The boy's brother was also found to have secundum ASD and first degree AV block. There were two sudden deaths in the family. Genetic testing revealed a novel mutation of NKX2.5 in all affected members of the family.

• Progress in Superconductivity
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• v.7 no.1
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• pp.28-35
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• 2005

We propose a method to measure atrial arrhythmias (AA) such as atrial fibrillation (Afb) and atrial flutter (Afl) with a SQUID magnetocardiograph (MCG) system. To detect AA is one of challenging topics in MCG. As the AA generally have irregular rhythm and atrio-ventricular conduction, the MCG signal cannot be improved by QRS averaging; therefore a SQUID MCG system having a high SNR is required to measure informative atrial excitation with a single scan. In the case of Afb, diminished f waves are much smaller than normal P waves because the sources are usually located on the posterior wall of the heart. In this study, we utilize an MCG system measuring tangential field components, which is known to be more sensitive to a deeper current source. The average noise spectral density of the whole system in a magnetic shielded room was $10\;fT/{\surd}Hz(a)\;1\;Hz\;and\;5\;fT/{\surd}Hz\;(a)\;100\;Hz$. We measured the MCG signals of patients with chronic Afb and Afl. Before the AA measurement, the comparison between the measurements in supine and prone positions for P waves has been conducted and the experiment gave a result that the supine position is more suitable to measure the atrial excitation. Therefore, the AA was measured in subject's supine position. Clinical potential of AA measurement in MCG is to find an aspect of a reentry circuit and to localize the abnormal stimulation noninvasively. To give useful information about the abnormal excitation, we have developed a method, separative synthetic aperture magnetometry (sSAM). The basic idea of sSAM is to visualize current source distribution corresponding to the atrial excitation, which are separated from the ventricular excitation and the Gaussian sensor noises. By using sSAM, we localized the source of an Afl successfully.

• Korean Circulation Journal
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• v.52 no.9
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• pp.699-711
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• 2022

Background and Objectives: We investigated whether extra-pulmonary vein (PV) ablation targeting a high maximal slope of the action potential duration restitution curve (Smax) improves the rhythm outcome of persistent atrial fibrillation (PeAF) ablation. Methods: In this open-label, multi-center, randomized, and controlled trial, 178 PeAF patients were randomized with 1:1 ratio to computational modeling-guided virtual Smax ablation (V-Smax) or empirical ablation (E-ABL) groups. Smax maps were generated by computational modeling based on atrial substrate maps acquired during clinical procedures in sinus rhythm. Smax maps were generated during the clinical PV isolation (PVI). The V-Smax group underwent an additional extra-PV ablation after PVI targeting the virtual high Smax sites. Results: After a mean follow-up period of 12.3±5.2 months, the clinical recurrence rates (25.6% vs. 23.9% in the V-Smax and the E-ABL group, p=0.880) or recurrence appearing as atrial tachycardia (11.1% vs. 5.7%, p=0.169) did not differ between the 2 groups. The post-ablation cardioversion rate was higher in the V-Smax group than E-ABL group (14.4% vs. 5.7%, p=0.027). Among antiarrhythmic drug-free patients (n=129), the AF freedom rate was 78.7% in the V-Smax group and 80.9% in the E-ABL group (p=0.776). The total procedure time was longer in the V-Smax group (p=0.008), but no significant difference was found in the major complication rates (p=0.497) between the groups. Conclusions: Unlike a dominant frequency ablation, the computational modeling-guided V-Smax ablation did not improve the rhythm outcome of the PeAF ablation and had a longer procedure time.

• Journal of Chest Surgery
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• v.38 no.11 s.256
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• pp.739-745
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• 2005

Background: The Maze procedure considered the most effective method of treatment for atrial fibrillation. However, the sinus conversion rates decreased due to several factors, especially enlarged left atrium. The purpose of this study was to investigate the effects of Maze procedure with aen atrial volume reduction plasty on rheumatic mitral valve disease, Material and Method: From December of 200f to July of 2004, 45 patients received mitral valve and Maze operation. The patients were placed in either group f or group 2, based on the left atrial volume reduction plasty. The presence and onset of sinus rhythm and the incidence of trans mitral A waves were monitored during the postoperative 7 days and throughout the follow up period of 3 and 6 months. Mean follow up periods were 15.8 10.1 months in group 1 and $6.1\pm2.7$ months in group 2. Result: The sinus onset were $9.88\pm12.2$ days in group 1, and $1\pm3.6$ days in group 2 (p<0.01). The sinus conversion rates in the group 1 and 2 were $65\%,\;75\%$ (p=0.07) in the postoperative 7 days, $70.5\%,\;100\%$ (p<0.01) at postoperative 3 months, and $93\%,\;100\%$ (p<0.01) at postoperative 6 months, respectively. The wave detection rates in the postoperative 7days were $31.2\%\;and\;63.6\%$, and continued to improve over time to $83.3\%\;and\;100\%$ by 6months, respectively. Conclusion: The results suggest that Maze procedure with left atrial volume reduction plasty is effective for inducing sinus rhythm and for restoring left atrial contractile function after concomitant rheumatic mitral valve surgery. However further follow up of this patients for long time is necessary.

• Journal of Chest Surgery
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• v.31 no.10
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• pp.939-944
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• 1998

Background: The sugical results of the Cox-Maze procedure (CMP) for lone atrial fibrillation(AF) have proven to be exellent. However, those for AF associated with mitral valve(MV) disease have been reported to be a little inferior. Materials and methods: To assess the efficacy and safety of the CMP as a combined procedure with MV operation, we studied retrospectively our experiences. Between April 1994 and October 1997, we experienced 70 (23 males, 47 females) cases of CMP concomitantly with MV operation. Results: The etiologies of MV disease were rheumatic in 67 and degenerative in 3 cases. The mean duration of AF before sugery was 66$\pm$70 months. Fifteen patients had the past medical history of thromboembolic complications, and left atrial thrombi were identified at operation in 24 patients. Twelve cases were reoperations. Aortic cross clamp (ACC) time was mean 151$\pm$44 minutes, and cardiopulmonary bypass (CPB) time was mean 246$\pm$65 minutes. Concomitant procedures were mitral valve replacement (MVR) in 19, MVR and aortic valve replacement (AVR) in 14, MVR and tricupid annuloplasty (TAP) in 8, MVR with AV repair in 3, MV repair in 11, MVR and coronary artery bypass grafting (CABG) in 2, MVR and AVR and CABG in 1, redo-MVR in 10, redo-MVR and redo-AVR in 2 patients. The rate of hospital mortality was 1.4%(1/70). Perioperative recurrence of AF was seen in 44(62.9%), and atrial tachyarrhythmias in 10(14.3%), low cardiac output syndrome in 4(5.7%), postoperative bleeding that required mediastinal exploration in 4(5.7%) patients. Other complications were acute renal failure in 2, aggravation of preoperative hemiplegia in 1, and transient delirium in 1 patient. We followed up all the survivors for 16.4 months(3-44months) on an average. Sinus rhythm has been restored in 65(94.2%) patients. AF has been controlled by operation alone in 73.9% and operation plus medication in 20.3%. Two patients needed permanent pacemaker implantation; one with sick sinus syndrome, and the other with tachycardia- bradycardia syndrome. Only two patients remained in AF. We followed up our patients with transthoracic echocardiography to assess the atrial contractilities and other cardiac functions. Right atrial contractility could be demonstrated in 92% and left atrial contractility in 53%.We compared our non-redo cases with redo cases. Although the duration of AF was significantly longer in redo cases, there was no differences in ACC time, CPB time, postoperative bleeding amount and sinus conversion rate. Conclusions: In conclusion, the CMP concomitant with MV operation demonstrated a high sinus conversion rate under the acceptable operative risk even in case of reoperation.

• Journal of Chest Surgery
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• v.42 no.2
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• pp.244-247
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• 2009

A left atrial appendage aneurysm is a very rare medical condition which can develop by an inflammatory reaction or a degenerative change. If there is no accompanying anomaly, a left atrial appendage is considered a congenital disease. The majority of left atrial appendage aneurysms are detected incidentally because they usually do not cause any symptoms. Surgery is indicated, even for asymptomatic patients, because of the risk of life-threatening complications, such as atrial fibrillation, supraventricular tachycardia, systemic embolization, and cardiac arrest. Left atrial appendage aneurysms are usually treated by a median sternotomy with extracorporeal circulation, especially if the aneurysm has a broad base or contains a thrombus, but can treated by thoracotomy without extracorporeal circulation. We report a case of a successfully treated left atrial appendage aneurysm that was misdiagnosed as a partial pericardial defect without extracorporeal circulation in a 13-year old child.

• Journal of Chest Surgery
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• v.51 no.4
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• pp.266-272
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• 2018

Background: Limited comparative data are available on the efficacy of cryoablation versus radiofrequency ablation in patients with atrial fibrillation. This study aimed to compare radiofrequency ablation and cryoablation with regard to clinical outcomes and the restoration of sinus rhythm or atrial contractility. Methods: A total of 239 patients who underwent surgical ablation between August 2003 and December 2016 at our institution were included. The patients were divided into 2 groups according to the energy device that was used (group A: n=140, radiofrequency ablator; group B: n=99, cryoablator). Echocardiographic data, overall survival, and major cardiovascular and cerebrovascular event (MACCE)-free survival were compared between the 2 groups. Results: At 1 year of follow-up, the atrial contractility recovery rate was 32.2% (19 of 59) in group A and 48.8% (21 of 44) in group B. In addition, cryoablation was found to be a predictive factor for the recovery of atrial contractility (cryoablation vs. radiofrequency ablation: odds ratio, 2.540; 95% confidence interval, 1.063-6.071; p=0.036). The left ventricular ejection fraction was significantly higher in group B ($53.1%{\pm}11.5%$ vs. $59.1%{\pm}6.3%$, p=0.001). The median follow-up duration was 36 months. The 5-year overall survival rate was $80.1%{\pm}3.6%$ in group A and $92.1%{\pm}2.9%$ in group B (p=0.400). The 5-year MACCE-free survival rate was $70.3%{\pm}4.0%$ in group A and $70.9%{\pm}5.6%$ in group B (p=0.818). Conclusion: Cryoablation was associated with a higher atrial contractility restoration rate and better left ventricular function than radiofrequency ablation. However, no significant relationship was observed between the energy source and overall or MACCE-free survival.

• Molecules and Cells
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• v.43 no.4
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• pp.408-418
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• 2020

The sinus node (SN) is located at the apex of the cardiac conduction system, and SN dysfunction (SND)-characterized by electrical remodeling-is generally attributed to idiopathic fibrosis or ischemic injuries in the SN. SND is associated with increased risk of cardiovascular disorders, including syncope, heart failure, and atrial arrhythmias, particularly atrial fibrillation. One of the histological SND hallmarks is degenerative atrial remodeling that is associated with conduction abnormalities and increased right atrial refractoriness. Although SND is frequently accompanied by increased fibrosis in the right atrium (RA), its molecular basis still remains elusive. Therefore, we investigated whether SND can induce significant molecular changes that account for the structural remodeling of RA. Towards this, we employed a rabbit model of experimental SND, and then compared the genome-wide RNA expression profiles in RA between SND-induced rabbits and sham-operated controls to identify the differentially expressed transcripts. The accompanying gene enrichment analysis revealed extensive pro-fibrotic changes within 7 days after the SN ablation, including activation of transforming growth factor-β (TGF-β) signaling and alterations in the levels of extracellular matrix components and their regulators. Importantly, our findings suggest that periostin, a matricellular factor that regulates the development of cardiac tissue, might play a key role in mediating TGF-β-signaling-induced aberrant atrial remodeling. In conclusion, the present study provides valuable information regarding the molecular signatures underlying SND-induced atrial remodeling, and indicates that periostin can be potentially used in the diagnosis of fibroproliferative cardiac dysfunctions.