Cardiac Arrhythmias–New Considerations

Chronobiological Aspects of the Heart Rhythm Disorders at the Change of Pulmonary Ventilation in Rat Model (Pathophysiology of Cardiac Arrhythmias) Part 1

Introduction Presently is well established, that most physiological functions of living organisms fluctuate with a circadian dependence. Many experimental and clinical studies have demonstrated that cardiovascular functions show a marked circadian rhythmicity (Smith et al., 1987; Henry et al., 1990). Circadian fluctuations occur both in blood pressure and heart rate, but also in the ocurrence […]

Chronobiological Aspects of the Heart Rhythm Disorders at the Change of Pulmonary Ventilation in Rat Model (Pathophysiology of Cardiac Arrhythmias) Part 2

The electrical stability of the heart in a hypoventilation/reoxygenation model The onset and development of ventricular arrhythmias depends on many factors to which some disorders of pulmonary ventilation also belong. However, not all consider the effect of the recovery of oxygen delivery (reoxygenation) after hypoxic episodes to be the onset or development of ventricular arrhythmias. […]

Chronobiological Aspects of the Heart Rhythm Disorders at the Change of Pulmonary Ventilation in Rat Model (Pathophysiology of Cardiac Arrhythmias) Part 3

Chronobiological aspects of preconditioning by systemic asphyxia Ventricular arrhythmia threshold – A measure of the electrical stability of the heart There is ample evidence that repeating brief periods of myocardial ischemia and reperfusion may provide protection against electrical instability of the heart evoked by subsequent ischemia/reperfusion injury. This mechanism, known as ischemic preconditioning (IPC), was […]

Late Ventricular Potentials in Cardiac and Extracardiac Diseases (Pathophysiology of Cardiac Arrhythmias) Part 1

Introduction Late ventricular potentials (LVPs) are low amplitude, high frequency waveforms, appearing in the terminal part of the QRS complex of the electrocardiogram (Barbosa et al, 2002; Olinic & Zdrenghea, 1998), generated by diseased myocardium. They may extend in the ST segment (Zimmermann et al, 1983). Late ventricular potentials may be also defined as fragmented […]

Late Ventricular Potentials in Cardiac and Extracardiac Diseases (Pathophysiology of Cardiac Arrhythmias) Part 2

Cardiomyopathies Cardiomyopathies are an important cause of SCD in young people. Arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC) is an inherited myocardial disease, characterized by fibro-fatty substitution of the right ventricle (Corrado & Thiene, 2006). The fibro-fatty areas can create reentry circuits, the substrate for repetitive ventricular arrhythmias and a delayed, fragmented activation font (Folino et al, […]

Late Ventricular Potentials in Cardiac and Extracardiac Diseases (Pathophysiology of Cardiac Arrhythmias) Part 3

Chronic obstructive pulmonary disease (COPD) COPD is an independent risk factor for cardiovascular morbidity and mortality (Celli et al, 2010). Potential explanations for this association include: smoking, negative cardiac consequences of dynamic hyperinflation, exercise limitations and hypoxemia (Celli et al, 2010; Priori et al, 2001). Carjea (Carjea, 2003) studied the prevalence and characteristics of late […]

Influence of Patern and Degree of Left Ventricular Hypertrophy on Cardiac Arrhythmias (Pathophysiology of Cardiac Arrhythmias)

Introduction Ventricular arrhythmias A large number of clinical and epidemiological studies [1,2] have reported a correlation between the mass increase of the left ventricle (LV) and the risk of disease or death. The prevalence of left ventricular hypertrophy (LVH) in patients with essential hypertension may be as high as 40% (12%-70%) [3]. It has been […]

Sleep-Related Breathing Disorders and Cardiac Arrhythmia (Pathophysiology of Cardiac Arrhythmias) Part 1

Introduction Sleep-disordered breathing (SDB) includes a range of conditions characterized by abnormalities in the frequency and/or depth of breathing during sleep. Cessations in breathing rhythm (apneas) are momentary and often cyclical, while reductions in breath amplitude (hypopneas) may be momentary or sustained (Dempsey et al., 2010). Obstructive sleep apnea (OSA)/hypopnea syndrome (HS), obesity hypoventilation syndrome, […]

Sleep-Related Breathing Disorders and Cardiac Arrhythmia (Pathophysiology of Cardiac Arrhythmias) Part 2

Pathophysiological mechanisms of arrhythmia in SDB The exact mechanisms linking SDB and arrhythmia are not completely understood, as there are several complex and interrelated pathways by which arrhythmias may be produced or become more severe in the presence of SDB. Autonomic, hemodynamic, chemical, inflammatory, and metabolic mechanisms may be involved to varying degrees in relation […]

Approach to Ventricular Arrhythmias in the Pediatric Intensive Care Unit (Pathophysiology of Cardiac Arrhythmias) Part 1

Introduction Ventricular arrhythmia was once regarded uncommon in infants and children, since most cardiac arrests were thought to be hypoxia-induced bradycardia followed by asystole. Furthermore, ischemic heart disease, the basis for many of the ventricular arrhythmias in adults, is rare in pediatric patients. However, with the advent of pediatric critical care, improved techniques of extracorporeal […]

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