Interactions Between Activation And Repolarisation In Predisposition Towards Cardiac Arrhythmia

The lethal cardiac arrhythmias ventricular fibrillation (VF) and ventricular tachycardia (VT) are a leading cause of death in heart disease. We hypothesised that dynamic activation and repolarisation interactions will vary according to autonomic tone and the nature of the myocardial substrate as affected by disease states. This hypothesis was tested in a series of human and murine experiments. Incorporation of data from human electrophysiological studies into a linear computer model was able to predict activation dynamics of sequential extrastimuli. This served as a validation of the concept of dynamic interactions between activation and repolarisation in man. A human model of mental stress demonstrated that activation and repolarisation dynamics are altered by intrinsic autonomic stimulation. Specifically, a reduction in activation potential duration and an increase in dispersion of repolarisation occurred at short coupling intervals during stress. A weak increase in conduction velocity and excitability was also observed. Patients with early-stage arrhythmogenic right ventricular cardiomyopathy (ARVC) were seen to exhibit conduction changes prior to the onset of structural disease. This was used to determine potential diagnostic criteria based on surface ECG correlates of intracardiac observations. These criteria are able to distinguish early ARVC from benign right ventricular outflow tract tachycardia. Finally, the mechanism of modulation of tissue level activation dynamics were further studied using a novel thin-tissue slice murine model. Conduction velocity and excitability were modulated by both sympathetic and parasympathetic stimuli, parasympathetic modulation is demonstrated to be dependent on the Gαi2 regulatory pathway at the tissue level. The tissue slice method provides a novel tissue-level platform for the study of cardiac electrophysiology in genetically modified mice. In conclusion, this work demonstrates that modulations of activation and repolarisation dynamics are seen in pro-arrhythmic states, specifically in sympathetically active states and in arrhythmogenic right ventricular cardiomyopathy

Ischemic Heart Disease in the Context of Different Comorbidities

Ischemic heart disease is a cardiovascular condition with very high prevalence worldwide and a major source of morbidity and mortality, especially in the geriatric population. The management of coronary artery disease is one that requires high-level expertise. The presence of comorbidities, usually multiple at advanced ages, makes the diagnosis and therapy very challenging. In this setting, the effort of a multidisciplinary team is urgently needed to achieve integrated management of these cases, being the only one capable of leading to the best results for the patient.The purpose of this reprint is to bring together the experience of specialists in treating ischemic heart disease in the presence of major related conditions that require particular modulations of diagnostic and therapeutic interventions. The chapters address difficult areas of interference between ischemic heart disease and frailty, cancer, liver diseases, inflammatory bowel disease and the new SARS-CoV-2 infection. Special consideration is granted to cardiac remodeling and progression to heart failure. Niche topics such as acute coronary syndromes triggered by carbon monoxide poisoning are present as well. The book also contains a particularly interesting chapter dedicated to the genetic substrate of ischemic heart disease, which once again emphasizes the need for a multidisciplinary team approach to this disease.We consider the reprint an excellent source of information for medical practitioners who have to solve complex cases of ischemic heart disease

Cardiac Arrhythmias

The most intimate mechanisms of cardiac arrhythmias are still quite unknown to scientists. Genetic studies on ionic alterations, the electrocardiographic features of cardiac rhythm and an arsenal of diagnostic tests have done more in the last five years than in all the history of cardiology. Similarly, therapy to prevent or cure such diseases is growing rapidly day by day. In this book the reader will be able to see with brighter light some of these intimate mechanisms of production, as well as cutting-edge therapies to date. Genetic studies, electrophysiological and electrocardiographyc features, ion channel alterations, heart diseases still unknown , and even the relationship between the psychic sphere and the heart have been exposed in this book. It deserves to be read