D. R. Rigney

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OBJECTIVES To determine the effects of congestive heart failure on a person's ability to walk at a steady pace while ambulating at a self-determined rate. SETTING Beth Israel Hospital, Boston, a primary and tertiary teaching hospital, and a social activity center for elderly adults living in the community. PARTICIPANTS Eleven elderly subjects (aged(More)
We describe the theory and computer implementation of a newly-derived mathematical model for analyzing the shape of blood pressure waveforms. Input to the program consists of an ECG signal, plus a single continuous channel of peripheral blood pressure, which is often obtained invasively from an indwelling catheter during intensive-care monitoring or(More)
OBJECTIVES The purpose of this report was to study heart rate variability in Holter recordings of patients who experienced ventricular fibrillation during the recording. BACKGROUND Decreased heart rate variability is recognized as a long-term predictor of overall and arrhythmic death after myocardial infarction. It was therefore postulated that heart rate(More)
Head-down bed rest is used to model physiological changes during spaceflight. We postulated that bed rest would decrease the degree of complex physiological heart rate variability. We analyzed continuous heart rate data from digitized Holter recordings in eight healthy female volunteers (age 28-34 yr) who underwent a 13-day 6 degree head-down bed rest study(More)
When excessive fluid accumulates in the pericardial space, the heart, suspended by the great vessels, is then free to swing as a pendulum. The swinging may occur at either the same frequency as the heart rate (1:1 oscillation) or at half the heart rate (2:1 oscillation), the latter frequency often arising during cardiac tamponade. We show that these two(More)
DNA topoisomerase I (Topo I) is an enzyme that alters the superhelicity of DNA. It has been implicated in such critical cellular functions as transcription, DNA replication, and recombination. Roles for Topo I in DNA repair following DNA damage have also been studied extensively. In the present investigation, we examined the regulation of Topo I expression(More)
Two-dimensional echocardiographic pictures from elderly patients are often technically unsatisfactory. It may be helpful or even necessary to improve the signal-to-noise ratio of these images before interpreting them. A novel picture-averaging method for obtaining the improved image is described here. The procedure may be performed with either live video or(More)