Pathological findings of myocardium in a patient with cardiac conduction defect associated with an SCN5A mutation.

A 16-year-old Japanese man was admitted to our hospital because of syncope during exercise. His father and his younger brother had permanent pacemaker implantation because of sick sinus syndrome. Several examinations revealed first-degree atrioventricular block, complete right bundle branch block, sick sinus syndrome, and ventricular tachycardia with normal cardiac function. As no abnormalities were evident on coronary angiography, right ventricular endomyocardial biopsy was performed. It showed myocardial disarrangement and lipofuscin accumulation in hypertrophic myocytes. Moreover, electron microscopy showed a few degenerative myocytes, Z-band streaming, disarrangement, increased small capillaries with Weibel-Palade bodies in endothelial cells, and endothelial proliferations. Genetic analysis of the proband, his father, and his younger brother revealed a missense mutation, D1275N, in SCN5A, a gene which encodes sodium ion channel protein, are related to cardiomyopathy and arrhythmia. The proband was diagnosed with a cardiac conduction defect (CCD) and underwent permanent pacemaker implantation. These pathological findings suggest various myocardial changes presented in CCD patients with a missense mutation, D1275N, in SCN5A.

Randomized, Open-Label, Cross-Over Comparison of the Effects of Benzbromarone and Febuxostat on Endothelial Function in Patients with Hyperuricemia.

Uric acid is generated with reactive oxygen species via xanthine oxidase (XO), and hyperuricemia, which is identified as the excess of uric acid in the blood, has been associated with vascular endothelial dysfunction. However, the effects of urate-lowering medicines on endothelial function have not been fully elucidated. Thus this study determined and compared the effects of benzbromarone (urate transporter 1 inhibitor) and febuxostat (XO inhibitor) on endothelial function.This randomized, cross-over, open-label study initially recruited 30 patients with hyperuricemia. They were divided into two groups, treated initially with benzbromarone or febuxostat for three months and then were switched for the next three months. Endothelial function was defined as reactive hyperemia indexes (RHI) determined using Endo-PAT 2000 before and at three and six months after medication using the two agents. Blood levels of asymmetric dimethylarginine (ADMA) and high-molecular-weight (HMW) adiponectin were also compared. We finally analyzed data from 24 patients whose endothelial function was assessed as described above.Our findings show that levels of uric acid significantly decreased, whereas those of HMW adiponectin and the RHI have significantly increased after treatment with benzbromarone. Meanwhile, in patients administered with febuxostat, uric acid levels tended to decrease and RHI significantly decreased. Neither of the two agents altered ADMA levels. The changes in RHI (P = 0.026) and HMW adiponectin levels (P = 0.001) were found to be significantly greater in patients treated with benzbromarone than febuxostat. Changes in the levels of HMW adiponectin and of uric acid were significantly correlated (r = -0.424, P = 0.039).Benzbromarone has increased adiponectin besides reducing uric acid levels, and thus, this might confer more benefits on endothelial function than febuxostat.

Postural Orthostatic Tachycardia in a Patient with Type 2 Diabetes with Diabetic Neuropathy.

A 24-year-old Japanese man with type 2 diabetes mellitus and diabetic neuropathy was admitted to our ward to evaluate the cause of orthostatic intolerance. During a head-up tilt test, his heart rate increased from 105 to 155 beats/minute within 3 minutes, and chest discomfort began. He was diagnosed with postural orthostatic tachycardia syndrome (POTS), and orthostatic intolerance disappeared after ß-blocker treatment. Scintigraphy using 123I-metaiodobenzylguanidine showed decreased cardiac uptake. Power spectral analysis of heart rate variability for 24 hours in Holter electrocardiography demonstrated decreases in both sympathetic and parasympathetic nervous system activities, with a greater decrease in parasympathetic activity than sympathetic activity. The relative sympathetic hyperactivity in the present patient with diabetic neuropathy seemed to be related to POTS.

Prognostic Significance of Premature Ventricular Contractions without Obvious Heart Diseases Determined by Standard 12-Lead Electrocardiography Considering their Morphology.

BACKGROUND: Although ventricular premature contraction (VPC) commonly arises in subjects with and without heart diseases, the prognosis of VPC has remained controversial and the effect of their morphology on mortality has not been fully determined in subjects without obvious heart diseases. The objective of this study was to assess the morphologic effect of VPC on mortality. METHODS: Japanese atomic bomb survivors (n = 6685) underwent baseline health examinations and standard 12-lead electrocardiogram (ECG) between January 1990 and December 1991. Of these, we extracted data from 5,685 (67.1% women) subjects who had neither heart diseases nor electrocardiographic abnormalities at baseline. Among them, we identified 131 VPC cases using standard 12-lead ECG and classified them into left bundle branch block (LBBB) type (n = 74), right bundle branch block (RBBB) type (n = 21), and undetermined type (n = 36) according to their morphology. These subjects were followed up until December 2008; we compared all-cause, cardiac and coronary heart disease (CHD) mortality rates using multivariate Cox regression analysis between those with and without VPC. RESULTS: No VPCs were associated with all-cause and cardiac mortality, but the LBBB type was significantly associated with CHD mortality (hazard ratio, 2.73; 95% confidence interval, 1.11-6.73) after controlling for age, sex, smoking status, alcohol consumption, and underlying diseases. CONCLUSIONS: Among Japanese atomic bomb survivors without obvious heart diseases, LBBB-type VPC was associated with increased CHD mortality. Larger studies are needed to confirm the effect of morphology as it might help to predict the risk.

Effective Management of Atrioventricular Interval for Paroxysmal Atrial Fibrillation That Developed After DDDR Pacemaker Implantation in a Sick Sinus Syndrome Patient.

A 68-year-old man with sick sinus syndrome (SSS) was referred to our department for pacemaker implantation. After implantation of a pacemaker with rate-responsive dual chamber (DDDR) mode and minimized ventricular pacing (MVP) functions, paroxysmal atrial fibrillation (PAF) repeatedly developed. Pacemaker memory showed that the intrinsic atrioventricular (AV) (atrial pacing-ventricular sensing [Ap-Vs]) interval was paradoxically prolonged during rate-responsive atrial single-chamber (AAIR) mode rapid pacing because of MVP. Accordingly, to eliminate the paradoxical prolongation of the AV interval during rapid atrial pacing, we changed MVP to medium AV hysteresis and conducted DDDR mode pacing with rate-dependent AV delay. PAF then sharply decreased without antiarrhythmic drugs.

Relationships Between Clinical Characteristics and Decreased Plakoglobin and Connexin 43 Expressions in Myocardial Biopsies From Patients With Arrhythmogenic Right Ventricular Cardiomyopathy.

Reduced expressions of plakoglobin and connexin 43 have been reported in the myocardium of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). However, the relationships between these expression abnormalities and the clinical features of ARVC remain unknown.The expressions of plakoglobin and connexin 43 in myocardial biopsy specimens from 10 patients with confirmed ARVC, and 13 control patients without ARVC (non-ARVC; hypertrophic cardiomyopathy, n = 7; dilated cardiomyopathy, n = 6), were examined by immunostaining to evaluate the relationships between these expressions and the clinical characteristics of ARVC. The ratios of plakoglobin/N-cadherin and of plakoglobin/connexin 43 expressions were significantly lower in the ARVC group than in the control group. Significantly more patients had decreased plakoglobin expression in the ARVC group than in the control group (9/10 versus 7/13; P = 0.0376). Sustained ventricular tachycardia occurred more frequently in patients with ARVC and with decreased expressions of both plakoglobin and connexin 43 than in those with decreased expression of plakoglobin alone (5/5 versus 1/4, P = 0.048).Decreased expressions of both connexin 43 and plakoglobin in the myocardium might be associated with the development of arrhythmia in ARVC.

Amyloid Deposition Mainly Localized in the Basal Area of the Left Ventricle in a Patient with Amyloid Transthyretin Cardiac Amyloidosis.

A 74-year-old Japanese man was admitted to our hospital for catheter ablation of paroxysmal atrial fibrillation. Transthoracic echocardiography revealed basal interventricular septal hypertrophy without apical sparing. Cardiac magnetic resonance imaging revealed late gadolinium enhancement in the hypertrophic lesions. The Kumamoto criteria was one point, and the patient had no carpal tunnel syndrome. However, technetium-99m pyrophosphate scintigraphy revealed an accumulation in the basal region of the left ventricle. A skin biopsy revealed transthyretin (TTR) amyloid deposition. A TTR gene examination revealed no variants. This case suggests that amyloid deposition in TTR may occur in the basal area of the interventricular septum.

Polymorphic Ventricular Tachycardia Associated with Coronary Vasospasm in a Patient with Coronavirus Disease 2019 Infection.

A 70-year-old man was admitted to our hospital for restoration of sinus rhythm from atrial fibrillation by direct current counter shocks. On admission, he had a coronavirus disease 2019 (COVID-19) infection and syncope during bed rest. Electrocardiography revealed polymorphic ventricular tachycardia after ST-segment elevation with a normal QT interval. Coronary angiography revealed coronary vasospasm. Coronary vasospasm may be a cause of polymorphic ventricular tachycardia in COVID-19 patients.

Successful management of heart failure 45 years after surgical correction of tetralogy of Fallot.

A 59-year-old Japanese woman was admitted with heart failure due to severe pulmonary regurgitation and tricuspid regurgitation, in addition to atrial fibrillation 45 years after surgical correction of tetralogy of Fallot (TOF). She had been under treatment with medication and catheter ablation for arrhythmia including ventricular tachycardia for the past 28 years. She underwent pulmonary valve replacement as well as tricuspid and mitral valvuloplasty, which obviously improved her status even though her right ventricular end-diastolic volume index exceeded the recommended threshold. Patients who have undergone surgical correction of TOF need to be managed over the long term. .

Sympathetic nerve abnormality in an adolescent patient with cardioinhibitory vasovagal syncope.

A 15 year-old-Japanese girl was admitted to our ward because of syncope. Electrocardiography (ECG) demonstrated sinus bradycardia with heart rate of 52/min. Holter ECG showed no arrhythmia related to syncope. Coronary enhanced computed tomography and cardiac magnetic resonance imaging showed no abnormal findings. Head-up tilt test revealed syncope with sinus arrest. 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy revealed focally decreased uptake on the anterior wall of the left ventricle but generally maintained uptake of MIBG. Finally, she was diagnosed with cardioinhibitory vasovagal syncope (CIVS). Sympathetic nerve abnormalities seemed to be related to CIVS in this patient. .

Correlation between Transient Hypotension and Exclusively Exercise-induced Symptoms of Two-to-One Atrioventricular Block.

A 62-year-old woman with activity-dependent two-to-one atrioventricular block (2:1AVB) and a normal left ventricular ejection fraction was referred to our department for the evaluation of exclusively exercise-induced marked symptoms. The treadmill test helped establish a clear correlation between 2:1AVB and symptoms. The test results demonstrated that exercise-induced marked symptoms were attributed to abrupt transient hypotension combined with relative bradycardia, probably due to increased diastolic mitral and tricuspid regurgitation because of 2:1AVB during moderate-to-heavy exercise. After pacemaker implantation for 2:1AVB, the symptoms and transient hypotension disappeared, and her exercise capacity improved.

Rivaroxaban therapy resulting in the resolution of right atrial thrombosis resistant to ordinary control with warfarin in a patient with atrial fibrillation.

A 72-year-old man with non-valvular atrial fibrillation and metastatic liver and lung cancer after surgery for colon cancer developed thrombosis in the right atrium one month after decreasing the dose of warfarin due to the introduction of double anti-platelet therapy for coronary stent implantation. Restoring the warfarin dose with ordinary control for two months did not result in any changes in the size of the thrombus; however, the subsequent substitution of rivaroxaban (oral treatment with a direct Factor Xa inhibitor) for warfarin ultimately resolved the thrombosis.

Sodium channelopathy underlying familial sick sinus syndrome with early onset and predominantly male characteristics.

BACKGROUND: Sick sinus syndrome (SSS) is a common arrhythmia often associated with aging or organic heart diseases but may also occur in a familial form with a variable mode of inheritance. Despite the identification of causative genes, including cardiac Na channel (SCN5A), the pathogenesis and molecular epidemiology of familial SSS remain undetermined primarily because of its rarity. METHODS AND RESULTS: We genetically screened 48 members of 15 SSS families for mutations in several candidate genes and determined the functional properties of mutant Na channels using whole-cell patch clamping. We identified 6 SCN5A mutations including a compound heterozygous mutation. Heterologously expressed mutant Na channels showed loss-of-function properties of reduced or no Na current density in conjunction with gating modulations. Among 19 family members with SCN5A mutations, QT prolongation and Brugada syndrome were associated in 4 and 2 individuals, respectively. Age of onset in probands carrying SCN5A mutations was significantly less (mean±SE, 12.4±4.6 years; n=5) than in SCN5A-negative probands (47.0±4.6 years; n=10; P<0.001) or nonfamilial SSS (74.3±0.4 years; n=538; P<0.001). Meta-analysis of SSS probands carrying SCN5A mutations (n=29) indicated profound male predominance (79.3%) resembling Brugada syndrome but with a considerably earlier age of onset (20.9±3.4 years). CONCLUSIONS: The notable pathophysiological overlap between familial SSS and Na channelopathy indicates that familial SSS with SCN5A mutations may represent a subset of cardiac Na channelopathy with strong male predominance and early clinical manifestations.

Cardiogenic shock due to left ventricular outflow obstruction and complete atrioventricular block in a patient with hypertrophic cardiomyopathy with acute myocarditis.

A 67-year-old woman was referred to our hospital with a sudden syncopal attack. She suffered from cardiogenic shock due to left ventricular (LV) outflow stenosis with simultaneous complete atrioventricular (AV) block. An endomyocardial biopsy of the left ventricle demonstrated myocardial disarray and myocardial fibrous and edematous tissue with infiltration of mononuclear cells. Cardiac magnetic resonance imaging (cMRI) detected a damaged septal area that was likely associated with the conduction disturbance. The diagnosis was hypertrophic cardiomyopathy accompanied by acute myocarditis. Although the LV outflow stenosis was transient, the complete AV block was persistent, thus requiring permanent pacemaker implantation.

Electrocardiographic characteristics and SCN5A mutations in idiopathic ventricular fibrillation associated with early repolarization.

BACKGROUND: Recently, we and others reported that early repolarization (J wave) is associated with idiopathic ventricular fibrillation. However, its clinical and genetic characteristics are unclear. METHODS AND RESULTS: This study included 50 patients (44 men; age, 45 ± 17 years) with idiopathic ventricular fibrillation associated with early repolarization, and 250 age- and sex-matched healthy controls. All of the patients had experienced arrhythmia events, and 8 (16%) had a family history of sudden death. Ventricular fibrillation was inducible by programmed electric stimulation in 15 of 29 patients (52%). The heart rate was slower and the PR interval and QRS duration were longer in patients with idiopathic ventricular fibrillation than in controls. We identified nonsynonymous variants in SCN5A (resulting in A226D, L846R, and R367H) in 3 unrelated patients. These variants occur at residues that are highly conserved across mammals. His-ventricular interval was prolonged in all of the patients carrying an SCN5A mutation. Sodium channel blocker challenge resulted in an augmentation of early repolarization or development of ventricular fibrillation in all of 3 patients, but none was diagnosed with Brugada syndrome. In heterologous expression studies, all of the mutant channels failed to generate any currents. Immunostaining revealed a trafficking defect in A226D channels and normal trafficking in R367H and L846R channels. CONCLUSIONS: We found reductions in heart rate and cardiac conduction and loss-of-function mutations in SCN5A in patients with idiopathic ventricular fibrillation associated with early repolarization. These findings support the hypothesis that decreased sodium current enhances ventricular fibrillation susceptibility.