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Ayako Tano, Yuji Kasamaki,
Yasuo Okumura,
Masakatsu Ohta,
Tatsuya Kofune,
Nobuyuki Fujii,
Yosihiro Aizawa,
Toshiko Nakai,
Satoshi Kunimoto,
Takafumi Hiro,
Ichiro Watanabe,
Atsushi Hirayama
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ABSTRACT: BACKGROUND: A sigmoid ventricular septum (SVS) may be related to normal aging, but some people with an SVS develop a left ventricular outflow tract (LVOT) obstruction (defined as a gradient of >30mmHg). Therefore, we investigated the association of LVOT obstructions with an SVS by dobutamine stress echocardiography (DSE) and assessed the possible mechanism of the latent LVOT obstruction. METHODS AND RESULTS: DSE was performed in 64 subjects with SVS (mean age: 73.3±7.7 years; 36 women) without an LVOT obstruction. In 40 of the 64 subjects, an LVOT obstruction occurred during the DSE (defined as latent obstruction). At rest, the subjects with a latent obstruction had a shorter end-systolic mitral leaflet tethering distance ("α" distance, i.e. the distance between the tip of the posterior papillary muscle and the contralateral anterior mitral annulus) than those without one (29.9±4.2mm versus 35.2±4.6mm), as well as a smaller end-systolic LVOT diameter (13.4±2.7mm versus 16.1±3.4mm) and larger ejection fraction (72.0±5.0% versus 67.8±5.9%) (all p<0.05). They also had a higher LV outflow velocity at rest (1.23±0.24m/s versus 1.03±0.24m/s) and during the Valsalva maneuver (1.31±0.27m/s versus 1.03±0.27m/s) (both p<0.05). After adjusting for these parameters, the resting end-systolic "α" distance and LV outflow velocity at rest remained independent predictors of a latent obstruction. CONCLUSION: A short leaflet tethering distance ("α") was the major determinant of a latent obstruction, suggesting that a mitral leaflet displacement/redundancy caused by a short "α" distance contributes to the LVOT obstruction.
Journal of Cardiology 03/2013; · 1.28 Impact Factor
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Jie Jiang,
Tomohiro Nakayama,
Masanori Shimodaira,
Naoyuki Sato,
Noriko Aoi,
Mikano Sato,
Yoichi Izumi, Yuji Kasamaki,
Masakatsu Ohta,
Masayoshi Soma,
Koichi Matsumoto,
Hiroshi Kawamura,
Yukio Ozawa,
Yitong Ma
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ABSTRACT: Smoothelin is a specific cytoskeletal protein that is associated with smooth muscle cells. The human SMTN gene encodes smoothelin-A and smoothelin-B, and studies using SMTN gene knockout mice have demonstrated that these animals develop hypertension. The aim of the present study was to investigate the association between the human SMTN gene and essential hypertension (EH) using a haplotype-based case-control study. This is the first study to assess the association between essential hypertension and this gene. A total of 255 EH patients and 225 controls were genotyped for the five single-nucleotide polymorphisms (rs2074738, rs5997872, rs56095120, rs9621187 and rs10304) used as genetic markers for the human SMTN gene. Data were analyzed for three separate groups: total subjects, men and women. Although there were no differences for genotype distributions, or the dominant and recessive model distributions noted for total subjects, men and women for all of the SNPs selected for the present study, for the total subjects group, the frequency of the G-C-A-C haplotype constructed with rs2074738-rs5997872-rs56095120-rs9621187 was significantly lower in the essential hypertension patients than in the controls (P = 0.002). The G-C-A-C haplotype appears to be a useful protective marker of essential hypertension in Japanese, and the SMTN gene might also be a genetic marker for essential hypertension.
Hereditas 10/2012; 149(5):178-185. · 0.79 Impact Factor
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Jie Jiang,
Tomohiro Nakayama,
Masanori Shimodaira,
Naoyuki Sato,
Noriko Aoi,
Mikano Sato,
Yoichi Izumi, Yuji Kasamaki,
Masakatsu Ohta,
Masayoshi Soma,
Koichi Matsumoto,
Hiroshi Kawamura,
Yukio Ozawa,
Shigeaki Hinohara,
Nobutaka Doba,
Yitong Ma
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ABSTRACT: Smoothelin is a specific type of cytoskeletal protein found in smooth muscle cells (SMCs). Several previous research studies have examined the relationship between smoothelin and atherosclerotic plaque. The aim of the present study was to further assess the association between the human SMTN gene and cerebral infarction (CI) using a haplotype-based case-control study. A total of 168 CI patients and 259 supercontrols were genotyped for the five single-nucleotide polymorphisms (SNPs) used as genetic markers for the human SMTN gene (rs2074738, rs5997872, rs56095120, rs9621187 and rs10304). Data were analyzed for three separate groups that included total subjects, men and women. The genotypic distribution of rs10304 for men showed a significant difference between the control and CI groups. In addition, the frequency of the C-T-T-A haplotype (established by rs5997872, rs56095120, rs9621187 and rs10304) was significantly higher in the CI versus the control group (p = 0.013), while the frequency of the C-A-T-G haplotype (established by rs5997872, rs56095120, rs9621187 and rs10304) in the CI group was significantly lower than that seen in the controls (p = 0.021). In conclusion, we confirmed that the haplotype constructed using rs5997872, rs56095120, rs9621187 and rs10304 was a useful genetic marker of CI in Japanese men.
Vascular Medicine 10/2012; 17(5):317-25. · 1.46 Impact Factor
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Jie Jiang,
Tomohiro Nakayama,
Masanori Shimodaira,
Naoyuki Sato,
Noriko Aoi,
Mikano Sato,
Yoichi Izumi, Yuji Kasamaki,
Masakatsu Ohta,
Masayoshi Soma,
Koichi Matsumoto,
Hiroshi Kawamura,
Yukio Ozawa,
Yitong Ma
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ABSTRACT: Objectives: Smoothelin is a specific kind of cytoskeletal protein present in smooth muscle cells. Some researchers have shown the relationship between smoothelin and atherosclerotic plaque. The human SMTN gene encodes smoothelin-A and smoothelin-B. The aim of the present study was to assess the association between the human SMTN gene and myocardial infarction (MI) using a haplotype-based case-control study. Methods: A total of 227 MI patients and 257 supercontrols were genotyped for five single-nucleotide polymorphisms used as genetic markers of the human smoothelin gene. Data were analyzed for three separate groups: total subjects, men, and women. Results: For the women, the frequency of the C-T-T-G haplotype (established by rs5997872, rs56095120, rs9621187, and rs10304) was significantly higher in the MI group than in the control group (p=0.012). Conclusions: We confirmed that the haplotype constructed using rs5997872, rs56095120, rs9621187, and rs10304 is a useful genetic marker of MI in Japanese females.
Genetic Testing and Molecular Biomarkers 09/2012; 16(9):1019-26. · 1.11 Impact Factor
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ABSTRACT: BACKGROUND: Cardiovascular disease is the leading cause of death among patients with chronic kidney disease (CKD). Therefore, stratification of the prognostic risk of cardiovascular events is useful for their clinical management. We evaluated the ability of electrocardiogram (ECG)-gated myocardial perfusion single photon emission computed tomography (SPECT) to predict cardiac events among Japanese patients at all stages of CKD including those on hemodialysis. METHODS: Patients with CKD undergoing ECG-gated myocardial perfusion SPECT to investigate suspected ischemic heart disease were followed up to monitor retrospectively major cardiac events including cardiac death, non-fatal myocardial infarction, and unstable angina pectoris. Summed stress score, summed rest score, and summed difference score were estimated with a 20 segment 5-point scoring model. The severity of CKD was divided into five levels based on estimated glomerular filtration rate (eGFR) revised for the Japanese population. RESULTS: The follow-up period was 25.8±11.0 months. Sixty-two major cardiac events (cardiac death, n=30; non-fatal myocardial infarction, n=13; unstable angina pectoris, n=19) developed in 2243 patients during the first year of follow-up. The findings of multivariate Cox proportional hazards regression analysis indicated that diabetes, eGFR, the summed difference score, and summed stress score were significant independent predictors of cardiac events. The major cardiac event rate at one year increased in proportion to the progression of CKD stage. The major cardiac event-free survival rate decreased steeply over time in patients with CKD stage 5 compared with those who had CKD stages 4 or less. CONCLUSION: Myocardial perfusion SPECT can contribute to the prediction of cardiac events and survival in patients at all stages of CKD including those on hemodialysis.
Journal of Cardiology 08/2012; · 1.28 Impact Factor
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Zhenyan Fu,
Tomohiro Nakayama,
Naoyuki Sato,
Yoichi Izumi, Yuji Kasamaki,
Atsushi Shindo,
Masakatsu Ohta,
Masayoshi Soma,
Noriko Aoi,
Mikano Sato,
Yukio Ozawa,
Yitong Ma
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ABSTRACT: CYP4A11, which is a member of the cytochrome P450 family, acts mainly as an enzyme that converts arachidonic acid to 20-hydroxyeicosatetraenoic acid (20-HETE), a metabolite involved in the maintenance of cardiovascular health. Recently, it was reported that many subfamilies of CYP genes have an association with myocardial infarction (MI). The aim of the present study was to assess the association between the human CYP4A11 gene and MI, using a haplotype-based case-control study with a separate analysis of the gender groups. A total of 239 MI patients and 285 controls were genotyped for 3 single-nucleotide polymorphisms (SNPs) of the human CYP4A11 gene (rs2269231, rs1126742, rs9333025). The data obtained via haplotype-based case-control studies were assessed for 3 separate groups: total subjects, men, and women. For the total, men and women groups, the distribution of the genotypes and alleles of the 3 SNPs did not show any significant difference between the MI patients and the control subjects. For the total and the men groups, the overall distribution of the haplotypes constructed with the 3 SNPs significantly differed between the MI patients and control subjects (P < 0.001). Also, for the total and for the men, the frequency of the T-T-A haplotype constructed with the 3 SNPs was significantly lower for the MI patients than for the control subjects (both P < 0.001). The T-T-A haplotype constructed with the 3 SNPs appears to be a protective genetic marker for MI in Japanese men.
Hereditas 06/2012; 149(3):91-8. · 0.79 Impact Factor
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ABSTRACT: Association between sudden cardiac arrest and early repolarization (QRS slurring in the inferolateral leads) has drawn recent attention. We retrospectively assessed the prevalence of electrocardiographic J waves in 19 men aged 46.5±13.7 years who, between 1979 and 2011, were resuscitated after cardiac arrest due to ventricular fibrillation. There was no structural heart disease in this group. The J wave is an elevation of the QRS-ST junction of at least 0.1mV from baseline in the inferior or lateral leads, manifested as QRS slurring or notching. Eleven patients (age, 37.3±13.9 years) showed J waves in the inferior leads (n=8) or in both the inferior and lateral leads (n=3). Brugada syndrome was diagnosed in 5 patients (age, 46.4±15.7 years). The QRS complex was normal in the remaining 3 patients (age, 44.3±9.5 years). Ventricular fibrillation was induced by programmed ventricular stimulation with up to 3 extrastimuli from the right ventricular apex or outflow tract in 7 of the 10 J-wave syndrome patients tested, in all 5 Brugada syndrome patients, and in all 3 patients with a normal electrocardiogram. There appears to be an increased prevalence of J-wave syndrome among patients with a history of idiopathic ventricular fibrillation.
Journal of Cardiology 03/2012; 59(3):313-20. · 1.28 Impact Factor
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Yuji Kasamaki,
Yoichi Izumi,
Yukio Ozawa,
Masakatsu Ohta,
Ayako Tano,
Ichiro Watanabe,
Atsushi Hirayama,
Tomohiro Nakayama,
Hiroshi Kawamura,
Dilxat Himit,
Maisumu Mahemuti,
Akira Sezai
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ABSTRACT: A relationship may exist between plasma atrial natriuretic peptide (P-ANP) and heart rate variability (HRV), which reflects the activity of the autonomic nervous system. We performed a survey in human subjects to examine the relationship between P-ANP and HRV parameters. Three ethnic groups (Han, Uygur, and Kazakh) provided blood and urine samples and underwent 24-h ambulatory blood pressure monitoring and 24-h ECG recording (24-h Holter ECG). There was a positive correlation between P-ANP and HF, as well as a negative correlation between P-ANP and the LF/HF ratio, in all subjects from the 3 ethnic groups. There was no association of BP with any of the blood, urinary, and HRV parameters. Our results suggested the possibility of a relationship between P-ANP and HRV, which reflects autonomic activity. These findings are consistent with the previous report of a close relationship between ANP and cardiac parasympathetic and/or sympathetic activity.
Heart and Vessels 02/2012; · 2.05 Impact Factor
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ABSTRACT: Adenosine and related compounds have been shown to produce atrioventricular (AV) conduction block during acute myocardial ischemia. We investigated the effects of the antianginal drug trapidil, which has been shown to inhibit phosphodiesterase, on AV conduction disturbances in a canine model of acute myocardial ischemia. In 35 anesthetized dogs, the AV node artery was cannulated and perfused with arterial blood. Adenosine (300 µg, 650 µg, or 1000 µg) was injected into the AV node artery. With administration of adenosine at 300 µg, 650 µg, or 1000 µg, the atrio-His (AH) interval was increased by 14.6 ms, 22.3 ms, and 29.7 ms, respectively. The effects of adenosine were potentiated by pretreatment with intravenous dipyridamole (250 µg/kg), an inhibitor of adenosine uptake, but the effects of adenosine were attenuated with intravenous trapidil (3 mg/kg), an inhibitor of phosphodiesterase. AV node artery occlusion resulted in prolongation of the AH interval in 4 of 12 dogs. The ischemia-induced AH prolongation was potentiated with intravenous dipyridamole and attenuated with intravenous trapidil. AV conduction disturbances associated with inferior myocardial infarction may be related in part to endogenously released adenosine, and trapidil may be useful in treating AV block associated with acute AV node ischemia.
International Heart Journal 01/2012; 53(3):187-92. · 1.16 Impact Factor
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Kimie Ohkubo,
Ichiro Watanabe,
Yasuo Okumura,
Masayoshi Kofune,
Koichi Nagashima,
Kazumasa Sonoda,
Hiroaki Mano,
Toshiko Nakai,
Satoshi Kunimoto, Yuji Kasamaki,
Atsushi Hirayama
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ABSTRACT: The stepwise approach to radiofrequency (RF) ablation of atrial fibrillation (AF) can include ablation of the coronary sinus (CS) by RF delivery at the left atrium (LA) and/or within the CS. In both cases, the energy is applied between the tip electrode of a percutaneous catheter and a dispersive electrode on the body surface. We explored the feasibility of using the electrode rings of a diagnostic catheter placed in the CS as dispersive electrode(s) for RF delivery within the LA and compared this technique to an established CS ablation method.Excised pig hearts were superfused with a pulsatile saline flow. Bipolar ablation was performed between a saline-irrigated (20 mL/minute) 4-mm tip electrode placed in the LA adjacent to the CS and 7 electrode rings of a 6F, septapolar, 4-mm nonirrigated electrode placed within the CS adjacent to the LA endocardial electrode. Unipolar ablation was performed between the endocardial electrode and dispersive electrode. A continuous transmural lesion was produced in 6/8 (75%) attempts with bipolar ablation, but in 0/6 (0%) attempts with unipolar ablation. However, the incidence of steam pop tended to be increased with bipolar ablation.Bipolar ablation of the CS appears to be highly effective for creating a transmural LA-CS lesion.
International Heart Journal 01/2012; 53(2):129-32. · 1.16 Impact Factor
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Koichi Nagashima,
Ichiro Watanabe,
Yasuo Okumura,
Kazumasa Sonoda,
Masayoshi Kofune,
Hiroaki Mano,
Kimie Ohkubo,
Toshiko Nakai,
Satoshi Kunimoto, Yuji Kasamaki,
Atsushi Hirayama
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ABSTRACT: Ablation of ventricular tachycardia originating from the left ventricular (LV) epicardium is often limited by the radiofrequency power delivery. We compared the effect of bipolar vs. unipolar epicardial ablation on lesion size.
Eleven excised pig hearts were superfused with saline (2 L/min). Unipolar ablation (25 or 30 W for 120 s) was performed between the LV epicardial saline-irrigated electrode and an indifferent electrode (n = 33 lesions). Bipolar ablation (25 or 30 W for 120 s) was performed between a 4-mm saline-irrigated-tip (20 ml/min) electrode on the LV epicardium and an opposing 10-mm non-irrigated-tip electrode on the LV endocardium (n = 38 lesions). Wall thickness did not differ between experiments (15.4 ± 2.4 vs. 15.3 ± 2.1 mm). Impedance was lower at the beginning and end of unipolar ablation than at the beginning and end of bipolar ablation (163.2 ± 20.3Ω and 109.9 ± 16.0Ω vs. 194.6 ± 23.3Ω and 127.1 ± 16.4Ω, respectively) (P<0.001). Epicardial lesion width did not differ between unipolar and bipolar ablation (10.1 ± 2.7 vs. 10.2 ± 2.4 mm), but lesion depth was greater with bipolar ablation (10.6 ± 2.7 vs. 7.5 ± 1.0 mm) (P<0.001). Unipolar ablation produced no transmural lesion, but bipolar ablation produced 15 (46%) (P<0.001). Steam pop occurred in 11 (29%) and 3 (9%) cases, respectively (P = 0.036).
Bipolar ablation of the LV free wall is highly effective at creating an appropriately deep epicardial lesion.
Circulation Journal 12/2011; 76(2):322-7. · 3.77 Impact Factor
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Sonoko Ashino,
Ichiro Watanabe,
Masayoshi Kofune,
Koichi Nagashima,
Kimie Ohkubo,
Yasuo Okumura,
Hiroaki Mano,
Toshiko Nakai,
Satoshi Kunimoto, Yuji Kasamaki,
Atsushi Hirayama
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ABSTRACT: On a cellular level, Brugada syndrome has been attributed to a deep phase 1 notch and subsequent shallow and prolonged repolarization in the right ventricular outflow tract (RVOT). A sodium channel mutation that leads to early inactivation of the late sodium current has been identified in some patients. Thus, drugs that inhibit the transient outward current (I(to)) responsible for the phase 1 notch and/or enhance the late sodium current might suppress arrhythmic events in patients with Brugada syndrome. The effects of quinidine gluconate, a potent inhibitor of I(to), on RVOT action potential duration (APD) restitution kinetics in patients with Brugada syndrome were evaluated.
Programmed ventricular stimulation was performed in 9 Brugada syndrome patients by delivering up to 3 extrastimuli from the right ventricular apex and RVOT. RVOT monophasic action potentials (MAPs) were recorded before and after intravenous administration of quinidine (n=6) or ibutilide (n=3). All patients had inducible ventricular fibrillation (VF) before drug administration. Both quinidine and ibutilide increased steady-state and minimum RVOT MAP duration during programmed stimulation. Quinidine decreased the maximum slope of the RVOT APD restitution curve and VF could not be induced after administration of quinidine in 5 of the 6 patients.
Quinidine appears to suppress the induction of VF by increasing RVOT MAP duration and decreasing the maximum slope of the restitution curve.
Circulation Journal 07/2011; 75(9):2080-6. · 3.77 Impact Factor
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ABSTRACT: We tested the efficacy and feasibility of percutaneous subxiphoid video pericardial endoscopy in five dogs. After percutaneous subxiphoid puncture, steerable 9F endoscope and 7F irrigated-tip catheters were advanced into the epicardial space. Epicardial vessels were visualized, and basal fat was distinguishable. Lesions created by the irrigated-tip catheter could be also appreciated on the epicardial surface. The endoscopic pericardial procedure was successful and may increase the efficacy and safety of epicardial irrigated radiofrequency catheter ablation.
Europace 04/2011; 13(10):1501-3. · 1.98 Impact Factor
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Yasuo Okumura,
Ichiro Watanabe,
Toshiko Nakai,
Kimie Ohkubo,
Tatsuya Kofune,
Masayoshi Kofune,
Koichi Nagashima,
Hiroaki Mano,
Kazumasa Sonoda, Yuji Kasamaki,
Atsushi Hirayama
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ABSTRACT: Although catheter ablation can effectively eliminate atrial fibrillation (AF), the progression of atrial remodeling increases the risk of recurrence. AF is associated with inflammation and subsequent myocardial fibrosis. We therefore examined the possibility of determining the postablation prognosis of patients with AF using biomarkers of inflammation and collagen turnover.
Subjects were 50 patients who underwent catheter ablation for drug-resistant AF. High-sensitivity CRP (hs-CRP), interleukin (IL)-6, carboxyl-terminal telopeptide of collagen type I (ICTP), metalloproteinase (MMP)-2, tissue inhibitor of MMP-2 (TIMP-2), atrial natriuretic peptide (ANP), and brain natriuretic peptide (BNP) were measured before and 2.2 ± 0.8 months after ablation. During the follow-up period of 14.0 (4.7-20.9) months, AF recurred in 21 of the 50 patients. Recurrence was associated with an MMP-2 elevation (860.3 ± 120.8 ng/mL vs 687.0 ± 122.5 ng/mL [in patients without recurrence]), ICTP elevation (3.2 ± 1.1 ng/mL vs 2.7 ± 0.6 ng/mL), BNP elevation, greater body mass index, nonparoxysmal AF, and hypertension (P < 0.05 for all). Serum MMP-2 and nonparoxysmal AF were shown by multivariate analysis to be independent predictors for postablation AF recurrence. Overall, hs-CRP, IL-6, ANP, and BNP levels decreased, and MMP-2, TIMP-2, and ICTP levels increased 2 months after ablation.
Our finding that markers of collagen turnover were elevated in patients who experienced AF recurrence after ablation indicate that these markers might be a useful guide to identify a subgroup of AF patients who require extensive ablation strategies. A 2-month postablation elevation in collagen turnover markers suggests that the wound healing process persists for that long after ablation.
Journal of Cardiovascular Electrophysiology 04/2011; 22(9):987-93. · 3.06 Impact Factor
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ABSTRACT: The International Conference on Harmonization E14 Guideline specifies detailed assessment of QT interval or corrected QT interval prolongation when developing new drugs. We recently devised new software to precisely measure the QT interval.
The QT intervals of all leads for a selected single heart beat were compared between automated measurement with the new software from Fukuda Denshi and manual measurement. With both automated and manual measurement, QT intervals obtained by the tangent method were shorter than those obtained by the differential threshold method, but the extent of correction was smaller. QT interval data obtained by the differential threshold method were more similar to values obtained by visual measurement than were data obtained by the tangent method, but the extent of correction was larger. Variability was related to the T-wave amplitude and to setting the baseline and tangent in the tangent method, while skeletal muscle potential noise affected the differential threshold method. Drift, low-amplitude recordings, and T-wave morphology were problems for both methods. Among the 12 leads, corrections were less frequent for leads II and V(3) -V(6) .
We conclude that, for a thorough assessment of the QT/QTc interval, the tangent method or the differential threshold method appears to be suitable because of smaller interreader differences and better reproducibility. Correction of data should be done by readers who are experienced in measuring the QT interval. It is also important for electrocardiograms to have little noise and for a suitable heart rate and appropriate leads to be selected.
Annals of Noninvasive Electrocardiology 04/2011; 16(2):156-64. · 1.10 Impact Factor
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ABSTRACT: Due to the difficulty in producing a transmural linear lesion and the possibility of complications such as thrombus formation leading to thromboembolism, the catheter-based maze procedure remains problematic. We tested, in pigs, the possibility of using a temperature-controlled cooled-tip radiofrequency (RF) ablation system together with a realtime position management (RPM) system to create a transmural linear lesion uncomplicated by thrombus formation.Nine pigs underwent insertion of two electrode catheters (each with two ultrasound electrodes), one into the coronary sinus (CS) and one into the right ventricular apex (references for ultrasound-based non-fluoroscopic three-dimensional mapping). A cooled-tip catheter (with two ultrasound electrodes) was introduced into the right atrium. Linear right atrial ablation was performed with a custom radiofrequency (RF) generator. The catheter was perfused with 0.66 mL/second of saline. RF was delivered for 60 seconds at a target temperature of 40°C. A linear ablation line was created between the superior vena cava and inferior vena cava. Three-dimensional isochronal maps were created during CS pacing before and after ablation. In 4 of the 9 pigs, a transmural linear ablation line was confirmed by three-dimensional mapping and postmortem macroscopic examination. No endocardial thrombus formation was noted. Temperature-controlled cooled-tip RF linear ablation guided by an RPM system appears to have potential for creating linear lesions in the atria. Further studies are needed to determine whether such an ablation technique and the parameters used will facilitate successful completion of the catheter-based maze procedure.
International Heart Journal 01/2011; 52(1):50-5. · 1.16 Impact Factor
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ABSTRACT: Increased action potential duration (APD) induces early afterdepolarization (EAD) in vitro and torsade de pointes in vivo, and ATP-sensitive K(+) channel openers decrease APD in cardiac tissue. We tested whether the ATP-sensitive K(+) channel opener nicorandil has antiarrhythmic effects on class III antiarrhythmic drug-induced ventricular arrhythmia. In 10 anesthetized dogs with chronic atrioventricular block, we recorded monophasic action potentials (MAPs) from the left and right ventricular (LV and RV) endocardium. The class III antiarrhythmic drug nifekalant (1 mg/kg, IV) was administered at 5 minute intervals (total doses; 2-6 mg/kg) until the appearance of EADs, premature ventricular contractions (PVCs), or polymorphic ventricular tachycardias (PVTs). Five minutes after the end of nifekalant administration, nicorandil (1.0 mg/kg) was administered over 5 minutes. Nifekalant decreased the ventricular escape rate from 75 ± 5 beats/minute to 45 ± 10 beats/minute and increased RV-MAP duration (MAPD) from 217 ± 32 msec to 308 ± 2 msec (P < 0.01) and LV-MAPD from 232 ± 32 msec to 353 ± 82 msec (P < 0.01). EADs were recorded in 9 dogs, frequent premature ventricular contractions (PVCs) developed in 10 dogs, incessant PVTs developed in 3 dogs, and monomorphic ventricular tachycardia developed in 3 dogs after nifekalant administration. Nicorandil decreased RV-MAPD to 267 ± 57 msec and LV-MAPD to 279 ± 44 msec. It suppressed EADs, decreased the incidence of PVCs, and abolished PVT. Nicorandil may be clinically useful for treatment of PVCs and PVTs accompanying acquired long QT syndrome.
International Heart Journal 01/2011; 52(5):318-22. · 1.16 Impact Factor
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ABSTRACT: The type 1 (coved) ECG pattern is diagnostic for Brugada syndrome; types 2 and 3 require antiarrhythmic drug challenge to confirm its presence. We evaluated a 12-lead ECG-based criterion to differentiate between ordinary incomplete right bundle branch block (iRBBB) and true type 2 and 3 patterns that evolve toward type 1 during drug challenge. The subjects were 22 patients (21 men, 1 woman; mean age, 46.8 ± 13.2 years) referred for drug challenge (1 mg/kg pilsicainide, iv). In magnified ECG lead V1 and/or V2 with an iRBBB pattern, the baseline angle defined as the cross section of the upslope of the r' wave with the downslope of the r' wave was measured and compared between patients responding negatively versus positively to drug challenge, and was found to be significantly smaller in patients responding negatively (20.9 ± 12.9°, n = 6, versus 38.7 ± 16.5°, n = 13; P = 0.009). This ECG-based method successfully discriminates between the ordinary iRBBB pattern and drug-induced evolution toward a type 1 Brugada ECG.
International Heart Journal 01/2011; 52(3):159-63. · 1.16 Impact Factor
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Kimie Ohkubo,
Ichiro Watanabe,
Yasuo Okumura,
Sonoko Ashino,
Masayoshi Kofune,
Koichi Nagashima,
Tatsuya Kofune,
Toshiko Nakai,
Satoshi Kunimoto, Yuji Kasamaki,
Atsushi Hirayama
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ABSTRACT: Brugada syndrome is an inherited disorder that predisposes some patients to sudden cardiac death. It is not well established which Brugada syndrome patients are at risk of life-threatening arrhythmias. We investigated whether standard 12-lead electrocardiograms (ECG) can identify such patients. The subjects were 35 men with Brugada syndrome (mean age, 50.1 ± 12.4 years). Documented ventricular fibrillation or aborted sudden cardiac arrests were judged to be related to the Brugada syndrome. Ten patients (mean age, 49.6 ± 14.9 years) were symptomatic, and 25 (mean age, 50.3 ± 11.5 years) were asymptomatic. We determined the PR interval, QRS duration, and QT interval from baseline 12-lead ECG leads II and V2 as well as the J point elevation amplitude of lead V2. The QRS interval was measured from QRS onset to the J point in leads II and V2. The only significant difference between the symptomatic and asymptomatic patients was the QRS duration measured from lead V2. The mean QRS interval was 129.0 ± 23.9 ms in symptomatic patients versus 108.3 ± 15.9 ms in asymptomatic patients (P = 0.012). A QRS interval in lead V2 ≥ 120 ms was found to be a possible predictor of a life-threatening ventricular arrhythmia and/or syncope (P = 0.012). Prolonged QRS duration as measured on a standard 12-lead ECG is associated with ventricular arrhythmia and could serve as a simple noninvasive marker of vulnerability to life-threatening cardiac events in patients with Brugada syndrome.
International Heart Journal 01/2011; 52(2):98-102. · 1.16 Impact Factor
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ABSTRACT: The right ventricular outflow tract (RVOT) is considered the arrhythmogenic region that gives rise to Brugada syndrome. To obtain a better understanding of this substrate, we performed electroanatomic mapping of the right ventricle (RV) in patients with Brugada syndrome. The RV was mapped electroanatomically with the CARTO system in 11 patients with asymptomatic Brugada syndrome but in whom ventricular fibrillation was induced by programmed ventricular stimulation, and in 5 control patients. The low voltage zone area (< 1.5 mV) was larger (16.1% versus 7.8%, P < 0.01) and the bipolar electrogram duration was greater (81.6 ± 7.8 ms versus 53.4 ± 5.6 ms, P < 0.01) in the patients with Brugada syndrome versus the control patients; the bipolar electrogram duration was greater in the septal portion and free wall of the RVOT. Our data suggest that regional endocardial conduction slowing based on structural abnormalities exists at the RVOT in Brugada syndrome.
International Heart Journal 01/2011; 52(5):290-4. · 1.16 Impact Factor
