Components of heart rate variability have attracted considerable attention in psychology and medicine and have become important dependent measures in psychophysiology and behavioral medicine. Quantification and interpretation of heart rate variability, however, remain complex issues and are fraught with pitfalls. The present report (a) examines the physiological origins and mechanisms of heart rate variability, (b) considers quantitative approaches to measurement, and (c) highlights important caveats in the interpretation of heart rate variability. Summary guidelines for research in this area are outlined, and suggestions and prospects for future developments are considered.

Blood pressure variability includes rhythmic and nonrhythmic fluctuations that, with the use of spectral analysis, appear as clear peaks or broadband power, respectively. This review offers a concise and critical description of the spectral methods most commonly used (fast Fourier transform versus autoregressive modeling, time-varying versus broadband spectral analysis) and an evaluation of their advantages and disadvantages. It also provides insight into the problems that still affect the physiological and clinical interpretations of data provided by spectral analysis of blood pressure and heart rate variability. In particular, the assessment of blood pressure and heart rate spectra aimed at providing indexes of autonomic cardiovascular modulation is discussed. Evidence is given that multivariate models--which allow evaluation of the interactions between changes in blood pressure, heart rate, and other biological signals (such as respiratory activity) in the time or frequency domains--offer a more comprehensive approach to the assessment of cardiovascular regulation than that represented by the separate analysis of fluctuations in blood pressure or heart rate only.

LAMP2 mutations typically cause multisystem glycogen-storage disease (Danon's disease) but can also present as a primary cardiomyopathy. The glycogen-storage cardiomyopathy produced by LAMP2 or PRKAG2 mutations resembles hypertrophic cardiomyopathy but is distinguished by electrophysiological abnormalities, particularly ventricular preexcitation.

No abstract

Cardiovascular variables such as heart rate, arterial blood pressure, stroke volume and the shape of electrocardiographic complexes all fluctuate on a beat to beat basis. These fluctuations have traditionally been ignored or, at best, treated as noise to be averaged out. The variability in cardiovascular signals reflects the homeodynamic interplay between perturbations to cardiovascular function and the dynamic response of the cardiovascular regulatory systems. Modern signal processing techniques provide a means of analyzing beat to beat fluctuations in cardiovascular signals, so as to permit a quantitative, noninvasive or minimally invasive method of assessing closed loop hemodynamic regulation and cardiac electrical stability. This method promises to provide a new approach to the clinical diagnosis and management of alterations in cardiovascular regulation and stability.