Publications by authors named "Sivalokanathan S"

Cardiac sarcoidosis (CS) is a rare entity characterized by granulomatous infiltration of the myocardium, which can lead to myocardial fibrosis, conduction abnormalities, and the development of heart failure, thereby elevating the risk of sudden cardiac death (SCD). While endomyocardial biopsy (EMBx) is regarded as the gold standard for diagnosis, its low sensitivity and inherent procedural risks may limit its practical application. This study retrospectively explored the role of advanced imaging modalities, specifically cardiovascular magnetic resonance imaging (CMR) and fluorodeoxyglucose positron emission tomography (FDG-PET), in the diagnosis and management of CS within a single center.

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Background: Signal-averaged electrocardiogram (SAECG) records myocardial depolarization, and can detect inhomogeneous/slow conduction in fibrotic myocardium, which promotes reentrant ventricular arrhythmias (VAs). Hypertrophic cardiomyopathy (HCM) is associated with a high prevalence of cardiac fibrosis and VAs, but abnormal SAECG has low predictive power for VAs. We hypothesized that HCM-specific structural/electrical remodeling underlies this result.

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Atrial fibrillation, the most common cardiac arrhythmia in the Western world, confers a 5-fold increase in stroke, mainly due to thrombus formation in the left atrial appendage. Early rhythm control is often beneficial in reducing adverse cardiovascular events in higher-risk populations. Here, we present a patient who was found to have a 1 cm stalk-like lesion in the left atrial appendage on transesophageal echocardiogram prior to electrical cardioversion.

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Introduction: Athletic training can result in electrical and structural changes of the right ventricle that may mimic phenotypical features of arrhythmogenic right ventricular cardiomyopathy (ARVC), such as T-wave inversion and right heart dilatation. An erroneous interpretation may have consequences ranging from false reassurance in an athlete vulnerable to cardiac arrhythmias, to unnecessary sports restriction in a healthy individual. The primary aim of this study was to define normal RV dimension reference ranges for academy adolescent footballers of different ethnicities.

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Background: The heart has metabolic flexibility, which is influenced by fed/fasting states, and pathologies such as myocardial ischemia and hypertrophic cardiomyopathy (HCM). Hyperpolarized (HP) C-pyruvate MRI is a promising new tool for non-invasive quantification of myocardial glycolytic and Krebs cycle flux. However, human studies of HP C-MRI have yet to demonstrate regional quantification of metabolism, which is important in regional ischemia and HCM patients with asymmetric septal/apical hypertrophy.

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Introduction: The healthy heart has remarkable metabolic flexibility that permits rapid switching between mitochondrial glucose oxidation and fatty acid oxidation to generate ATP. Loss of metabolic flexibility has been implicated in the genesis of contractile dysfunction seen in cardiomyopathy. Metabolic flexibility has been imaged in experimental models, using hyperpolarized (HP) [2- C]pyruvate MRI, which enables interrogation of metabolites that reflect tricarboxylic acid (TCA) cycle flux in cardiac myocytes.

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Introduction: The normal heart has remarkable metabolic flexibility that permits rapid switching between mitochondrial glucose oxidation and fatty acid (FA) oxidation to generate ATP. Loss of metabolic flexibility has been implicated in the genesis of contractile dysfunction seen in cardiomyopathy. Metabolic flexibility has been imaged in experimental models, using hyperpolarized (HP) [2-C]pyruvate MRI, which enables interrogation of metabolites that reflect tricarboxylic acid (TCA) cycle flux in cardiac myocytes.

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Background: The heart has metabolic flexibility, which is influenced by fed/fasting states, and pathologies such as myocardial ischemia and hypertrophic cardiomyopathy (HCM). Hyperpolarized (HP) C-pyruvate MRI is a promising new tool for non-invasive quantification of myocardial glycolytic and Krebs cycle flux. However, human studies of HP C-MRI have yet to demonstrate regional quantification of metabolism, which is important in regional ischemia and HCM patients with asymmetric septal/apical hypertrophy.

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Background: Coronary microvascular dysfunction (CMD) and hypertension (HTN) occur frequently in hypertrophic cardiomyopathy (HCM), but whether blood pressure (BP) influences CMD and outcomes is unknown.

Objective: The purpose of this study was to test the hypothesis that HTN is associated with worse CMD and outcomes.

Methods: This retrospective study included 690 HCM patients.

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Bicuspid aortic valve and aortopathy are generally considered contraindications to isometric exercise. For athletes with mild disease at low risk of adverse events, a shared decision-making approach for continued sports participation is reasonable. We present a case of a collegiate wrestler with bicuspid aortic valve and aortopathy to illustrate shared decision making.

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Background: The right ventricle (RV) in hypertrophic cardiomyopathy (HCM) tends to be neglected, as previous efforts have predominantly focused on examining the prognostic value of left ventricular (LV) abnormalities. The objectives of this study were to assess RV function in HCM, changes over time, and association with clinical outcomes.

Methods: Two hundred and ninety HCM patients with preserved LV ejection fraction (LVEF ≥ 55%) and 30 age- and sex-matched controls underwent cardiovascular magnetic resonance (CMR).

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Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disorder, affecting 1 out of 500 adults globally. It is a widely heterogeneous disorder characterized by a range of phenotypic expressions, and is most often identified by non-invasive imaging that includes echocardiography and cardiovascular magnetic resonance imaging (CMR). Within the last two decades, cardiac magnetic resonance imaging (MRI) has emerged as the defining tool for the characterization and prognostication of cardiomyopathies.

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Coronavirus disease 2019 (COVID-19) is an infectious respiratory disease that is often the trigger for thrombotic complications. Cerebral venous sinus thrombosis (CVST) represents a small percentage of strokes, frequently proving to be a diagnostic challenge. We report a 31-year-old lady presenting with a persistent headache, 18 weeks after a mild COVID-19 illness.

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Background: Coronavirus disease 2019 (COVID-19) myocarditis is emerging as a component of the hyperactive inflammatory response secondary to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Isolated gastrointestinal symptoms are uncommon presenting features in adults with COVID-19 myocarditis. The availability of antibody testing is a valuable addition to the confirmation of COVID-19, when repeated reverse transcriptase-polymerase chain reaction of nasopharyngeal swabs are negative.

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Several performance-enhancing or ergogenic drugs have been linked to both significant adverse cardiovascular effects and increased cardiovascular risk. Even with increased scrutiny on the governance of performance-enhancing drugs (PEDs) in professional sport and heightened awareness of the associated cardiovascular risk, there are some who are prepared to risk their use to gain competitive advantage. Caffeine is the most commonly consumed drug in the world and its ergogenic properties have been reported for decades.

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Objectives: This study hypothesized that paroxysmal atrial fibrillation (PAF) reflects the presence of a more severe cardiac hypertrophic cardiomyopathy (HCM) phenotype.

Background: HCM is characterized by myocyte hypertrophy, fibrosis, and a high prevalence of PAF. It is currently unresolved whether atrial fibrillation (AF) is a marker or a mediator of adverse outcomes in HCM.

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Background: Vasodilator-induced transient left ventricular cavity dilation (LVCD) by positron emission tomography (PET) is associated with microvascular dysfunction in hypertrophic cardiomyopathy (HCM). Here we assessed whether HCM patients who develop LVCD by PET during vasodilator stress also develop LV cavity dilation by echocardiography (ECHO-LVCD) following exercise stress.

Methods: A retrospective analysis of cardiac function and myocardial blood flow (MBF) was conducted in 108 HCM patients who underwent perfusion-PET and exercise-ECHO as part of their clinical evaluation.

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Aims: Myocardial fibrosis as detected by late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) is a powerful prognostic marker in hypertrophic cardiomyopathy (HCM) and may be progressive. The precise mechanisms underlying fibrosis progression are unclear. We sought to assess the extent of LGE progression in HCM and explore potential causal mechanisms and clinical implications.

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Patients with hypertrophic cardiomyopathy (HC) are at increased risk of sudden cardiac death. Abnormalities in myocardial blood flow (MBF) detected by positron emission tomography (PET) are common in HC, but a PET marker that identifies patients at risk of sudden cardiac death is lacking. We hypothesized that disparities in regional myocardial perfusion detected by PET would identify patients with HC at risk of ventricular arrhythmias.

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Background: Hypertrophic cardiomyopathy (HCM) is characterized by myocyte hypertrophy, disarray, fibrosis, and increased risk for ventricular arrhythmias. Increased QT dispersion has been reported in patients with HCM, but the underlying mechanisms have not been completely elucidated. In this study, we examined the relationship between diffuse interstitial fibrosis, replacement fibrosis, QTc dispersion and ventricular arrhythmias in patients with HCM.

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Amyotrophic lateral sclerosis is a neuromuscular disease characterized by selective loss of motor neurons leading to fatal paralysis. We previously reported a coding mutation in D-amino acid oxidase (R199W DAO) associated with familial amyotrophic lateral sclerosis. DAO metabolizes D-serine, a co-agonist at the N-methyl-D-aspartic acid receptor.

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