Part of the book: Cardiac Arrhythmias
Part of the book: Cardiac Arrhythmias
Signal-averaged ECG (SAECG) is a high-resolution, noninvasive electrocardiographic method enabling detection of late ventricular potentials (LVP), which are low-amplitude and high-frequency signals, predicting reentry ventricular arrhythmias, and sudden cardiac death (SCD). Three criteria are used to detect late ventricular potentials as follows: signal-average ECG QRS duration (SAECG-QRS), the duration of the terminal part of the QRS complex with an amplitude below 40 μV (LAS40) and the root mean square (RSM) signal amplitude of the last 40 ms of the signal < 20 μV (RMS40). Late ventricular potentials can be detected not only at the end of a QRS complex but also as intra-QRS (IQRS) potentials. Signal-averaged ECG was modified to enable the analysis of the P-wave and to detect atrial late potentials (ALPs), low-amplitude potentials at the terminal part of the filtered P-wave, and predictors of atrial fibrillation (AF). Late atrial and ventricular potentials originate from areas of delayed, fragmented, and heterogenous conduction within atrial or ventricular myocardium. This chapter reviews the most important mechanisms explaining the occurrence of late ventricular, intra-QRS, and atrial potentials; their predictive value for arrhythmia, focusing on recent clinical data, long-term follow-up, and outcome; and analysis of SAECG variables in cardiac and noncardiac diseases.
Part of the book: Interpreting Cardiac Electrograms
Several studies reported the cross talk between oral health and cardiovascular disorders. The aim of the present chapter is to review the main mechanisms linking oral and cardiovascular disorders, the main pathologies which could be linked, and possibilities for prophylactic and therapeutic interventions. Periodontitis was associated with cardiovascular risk, and the links between the two entities are represented by bacteria and their toxins released into the blood, causing endothelial dysfunction and providing a proatherogenic and prothrombotic effect and an inflammatory and immune reaction. The mentioned mechanisms explain the reported associations of periodontitis with stroke, coronary heart disease, and peripheral vascular disease. Periodontitis was also associated with diabetes mellitus and impaired lipid metabolism. Not all studies confirmed the association between periodontitis and coronary artery disease or stroke. Tooth loss, the most important consequence of periodontitis, has been also associated with cardiovascular disease. Dental and pulpal caries were also found to be independent risk factors for atherosclerosis, while restorations were inversely related to an atherosclerotic burden. Sucrose is involved in both cariogenesis and atherosclerosis. Fluorides prevent aortic calcifications and enamel demineralization and inhibit bacterial metabolism but are cardiotoxic. Heightening awareness of good dental hygiene can improve cardiovascular health.
Part of the book: Understanding the Molecular Crosstalk in Biological Processes