Roddy Hiram

• doctor of Physiology & Pharmacology
• Professor/Investigator at Montreal Heart Insitute - University of Montreal

Background: Conditions affecting the right heart, including diseases of the lungs and pulmonary circulation, promote atrial fibrillation (AF), but the mechanisms are poorly understood. Objectives: This study sought to determine whether right heart disease promotes atrial arrhythmogenesis in a rat model of pulmonary hypertension (PH) and, if so,...

Aims Recent studies suggest that bioactive mediators called resolvins promote an active resolution of inflammation. Inflammatory signalling is involved in the development of the substrate for atrial fibrillation (AF). The aim of this study is to evaluate the effects of resolvin-D1 on atrial arrhythmogenic remodelling resulting from left ventricular...

Aims Right heart disease (RHD), characterized by right ventricular (RV) and atrial (RA) hypertrophy, and cardiomyocytes’ (CM) dysfunctions have been described to be associated with the incidence of atrial fibrillation (AF). Right heart disease and AF have in common, an inflammatory status, but the mechanisms relating RHD, inflammation, and AF remai...

INTRODUCTION: Atrial Fibrillation (AF) is the most common cardiac arrhythmia. Hypertension, obesity, diabetes or right heart disease (RHD) are important risk factors for AF. Inflammation stands as a common denominator among most AF risk factors. Studies have shown that patients with AF present high levels of circulating IL-18. Our group recently de...

Introduction: Atrial Fibrillation (AF) is the most frequent cardiac arrhythmia. AF can lead to severe complications such as myocardial infarction, strokes, and sudden death. With 70% of AF patients aged 65 and older, aging stands as the major risk factor for AF. Our group have recently contributed to reveal that old Wistar rats (20 months) are more...

Background: Atrial Fibrillation (AF) is the most diagnosed cardiac arrhythmia in clinical practice. Catheter ablation (ABLA) is a method used to manage AF by cauterizing the left atrium (LA) to isolate arrhythmogenic areas. However, ABLA is paradoxically associated with atrial inflammation and AF recurrence, with 10% of patients experiencing recurr...

Aims Changes in myocardial mitochondrial morphology and function in premature ventricular contractions (PVCs)-induced cardiomyopathy (PVCCM) remain poorly studied. Here, we investigated the effects of PVCs with different coupling intervals (CIs) on myocardial mitochondrial remodelling in a canine model of PVCCM. Methods and Results Twenty-one beag...

Aims Cellular senescence is a stress-related or aging response believed to contribute to many cardiac conditions; however, its role in atrial fibrillation (AF) is unknown. Age is the single most important determinant of the risk of AF. The present study was designed to (i) evaluate AF susceptibility and senescence marker expression in rat models of...

Highlights What are the main findings? Abnormally increased concentrations of ingested or inhaled pollutants can lead to cardiac oxidative stress and inflammation. Untreated cardiac inflammation promotes myocardial fibrosis and cardiac arrhythmias. What is the implication of the main findings? Patients hospitalized for acute pesticide poisoning of...

Aims: Transglutaminase (TG) inhibitors represent promising therapeutic interventions in cardiac fibrosis and related dysfunctions. However, it remains unknown how TG inhibition, TG2 in particular, affects the signaling systems that drive pathological fibrosis. This study aimed to examine the effect TG inhibition by cystamine on the progression of...

Transglutaminase (TG) isoforms control diverse normal and pathophysiologic processes through their capacity to cross-link extracellular matrix (ECM) proteins. Their functional and signalling roles in cardiac fibrosis remain poorly understood, despite some evidence of TG2 involvement in abnormal ECM remodelling in heart diseases. In this study, we i...

Atrial fibrillation (AF) is the most common cardiac arrhythmia associated with increased cardiovascular morbidity and mortality. The pathophysiology of AF is characterized by electrical and structural remodeling occurring in the atrial myocardium. As a source of production of various hormones such as angiotensin-2, calcitonin, and atrial natriureti...

Background: Malignant ventricular arrhythmia (VA) is a major contributor to sudden cardiac death (SCD) in patients with pulmonary arterial hypertension (PAH)-induced right heart failure (RHF). Recently, dapagliflozin (DAPA), a sodium/glucose cotransporter-2 inhibitor (SGLT2i), has been found to exhibit cardioprotective effects in patients with lef...

Inflammation has been implicated in atrial fibrillation (AF), a very common and clinically significant cardiac rhythm disturbance, but its precise role remains poorly understood. Work performed over the past 5 years suggests that atrial cardiomyocytes have inflammatory signalling machinery - in particular, components of the NLRP3 (NACHT-, LRR- and...

Cardiac diseases are the leading cause of mortality and morbidity worldwide. Mounting evidence suggests that transglutaminases (TGs), tissue TG (TG2) in particular, are involved in numerous molecular responses underlying the pathogenesis of cardiac diseases. The TG family has several intra- and extracellular functions in the human body, including c...

Chronic heart diseases have in common an unresolved inflammatory status. In atherosclerosis, myocarditis, myocardial infarction, or atrial fibrillation, mounting evidence suggests that unresolved inflammation contributes to the chronicity, aggravation, and morbidity of the disease. Following cardiac injury or infection, acute inflammation is a norm...

Introduction Atrial fibrillation (AF) is the most commonly diagnosed cardiac arrhythmia. The genet mutation Myl4-pE11k affecting the atrial cardiomyocyte contractile machinery, via a myosin light chain abnormality, is associated with familial AF. The underlying pathophysiological mechanisms governing the through which the Myl-4 mutation causes AF r...

Inflammation is a complex program of active processes characterized by the well-orchestrated succession of an initiation and a resolution phase aiming to promote homeostasis. When the resolution of inflammation fails, the tissue undergoes an unresolved inflammatory status which, if it remains uncontrolled, can lead to chronic inflammatory disorders...

Atrial fibrillation is associated with aging, obesity, heart disease, diabetes, and/or hypertension. Recent evidence suggests that parenchymal and vascular lung diseases increase atrial fibrillation risk. We review the epidemiology, clinical features, pathophysiologic mechanisms, and treatment implications of atrial fibrillation associated with dis...

Peptidylarginine deiminase (PAD) family members have a vital role in maintaining the stability of the extra-cellular matrix (ECM) during remodelling in several heart diseases. PAD-mediated deamination, or citrullination, has been studied in different physiological and pathological conditions in the body. However, the role of PAD isoforms has not be...

Aims: Inflammation plays a role in atrial fibrillation (AF), but classical anti-inflammatory molecules are ineffective. Recent evidence suggests that failure of inflammation-resolution causes persistent inflammatory signaling and a novel drug-family called resolvins promotes inflammation-resolution. Right heart disease (RHD) is associated with AF;...

Background Atrial flutter (AFL) and atrial fibrillation (AF) are associated with AF-promoting atrial remodeling, but no experimental studies have addressed remodeling with sustained AFL. Objectives This study aimed to define the atrial remodeling caused by sustained atrial flutter (AFL) and/or atrial fibrillation (AF). Methods Intercaval radiofre...

Aims No studies have assessed the specific contributions of atrial fibrillation (AF)-related atrial vs. associated ventricular arrhythmia to remodelling. This study assessed the roles of atrial arrhythmia vs. high ventricular rate in AF-associated remodelling. Methods and results Four primary dog-groups (12/group) were subjected to 3-week pacing:...

Plate S1. Pharmacological effects of MAG‐DPA on GPR‐32 protein expression in TNF‐α‐pretreated human bronchi. Plate S2. Effects of MAG‐DPA on GPR‐32 protein expression in IL‐13‐pretreated human bronchi.

Bronchial inflammation contributes to a sustained elevation of airway hyperresponsiveness (AHR) in asthma. Conversely, omega-3 fatty acid derivatives have been shown to resolve inflammation in various tissues. Thus the effects of docosapentaenoic acid monoacylglyceride (MAG-DPA) were assessed on inflammatory markers and reactivity of human distal b...

Pulmonary hypertension (PH) is a disease of the lung vessels involving abnormal vasoconstriction which limits lung blood circulation and oxygenation. Despite current pharmacological treatments, PH still remains associated with high morbidity. Our hypothesis is that systemic lung inflammation may be resolved via relevant treatment in a rat model of...

L'inflammation pulmonaire contribue à l'augmentation de l'hyperréactivité bronchique (HRB) chez les patients souffrant d'asthme chronique. Des études ont démontré le rôle potentiel du monoacylglycéride de l'acide docosapentaénoique (MAG‐DPA), un dérivé d'oméga‐3, dans des maladies comme le cancer colorectal (Morin et al., 2013) et l'hypertension ar...

Pulmonary hypertension (PH) is a rare disease in which pathophysiology is characterized by an increase in pro-inflammatory mediators, chronic endothelial dysfunctions and a high migration rate of smooth muscle cells (SMC). During the course of the last decade, various treatments have been proposed to relax the pulmonary arteries, none of which have...

Introduction L’hypertension artérielle pulmonaire (HTAP) est une maladie progressive caractérisée par une augmentation anormale des résistances vasculaires pulmonaires. La dysfonction endothéliale a été démontrée et a permis d’élaborer des traitements, mais la composante inflammatoire reste encore un aspect mal compris de l’HTAP. Les omégas-3 à lon...

Pulmonary Hypertension (PH) is a rare and progressive disease characterized by an inflammatory status and vessel wall remodeling, resulting in increased pulmonary artery resistance. Hence PH remains associated with significant morbidity. We hypothesize that inflammation plays a crucial role in the severity of the abnormal vasoconstriction in PH. Th...

N-3 polyunsaturated fatty acids (n-3 PUFA) have been shown to reduce inflammation and proliferation of pulmonary artery smooth muscle cells under pathophysiological conditions. However, the anti-inflammatory effect of the newly synthesized docosapentaenoic acid monoacylglyceride MAG-DPA on key signaling pathways in pulmonary hypertension (PH) patho...

Pulmonary Hypertension (PH) is a rare and progressive disease characterised by an inflammatory status and vessel wall remodeling, resulting in an increased pulmonary arteries resistance. In the last 20 years, pharmacological treatments have been proposed. However PH remains associated with an important morbidity. Recent studies demonstrate that ome...

Pulmonary Hypertension (PH) is a rare and progressive disease characterised by an inflammatory status and vessel wall remodeling, resulting in an increased pulmonary arteries resistance. In the last 20 years, pharmacological treatments have been proposed. However PH remains associated with an important morbidity. Recent studies demonstrate that ome...