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Biomedical subjects

T A Preston

Publications and source records attributed to T A Preston.

At least 55 records · Page 3Linked to original sources
PubMed1977

Drug management of stable angina pectoris.

Nitroglycerin and long-acting nitrates are the pharmacologic mainstays of antianginal therapy, both for acute attacks and for prophylaxis. Propranolol is often effective for prophylaxis in patients incompletely helped by nitrates. A holistic approach is stressed. Appropriate drug use will effect marked improvement in most pateints.

Angina Pectoris↗
PubMed1976

Personality patterns in insomnia. Theoretical implications.

Subjects with a primary complaint of insomnia (N = 124) were evaluated with Minnesota Multiphasic Personality Inventories (MMPIs). A high percentage of subjects (85%) had one or more MMPI scales elevated to a pathological degree. The scales most elevated were, in order. 2 (depression), 7 (psychasthenia), and 3 (conversion hysteria). A striking finding was the preponderance of depression. This was indicated by the frequency in which scale 2 was elevated above 70, the frequency in which this this scale had the highest elevation, and the frequency of MMPI code types that included scale 2. Four common MMPI code types representing various types of depression were noted, indicating considerable homogeneity for code types in this sample. The predominant personality styles in this sample were characterized by the internalization of psychological distrubances rather than by acting out or aggression. We propose that this internalization produces a state of constant emotional arousal and resultant physiological activation and that this process is a psychophysiological mechansim underlyling insomnia.

Adolescent↗
PubMed1976

Temporary unipolar pacing using a dual cathode.

Using standard biopolar, temporary pacing catheters, thresholds were measured in four configurations: (1) bipolar (distal electrode negative, proximal electrode positive); (2) distal unipolar (distal electrode negative, right arm electrode positive); (3) proximal unipolar (proximal electrode negative, right arm electrode positive); (4) dual-cathode unipolar (distal and proximal electrodes negative, right arm electrode positive). With one exception, the bipolar threshold was the lower of the distal or proximal unipolar thresholds, suggesting that bipolar temporary pacing is reliable because one of the two electrodes is in good contact with the endocardium. In both the distal and proximal unipolar configurations there were numerous instances of high threshold and failure to pace. However, with one exception, in all cases either the distal or proximal unipolar threshold was normal and thus pacing was possible and effective in the dual-cathode configuration. Dual-cathode unipolar pacing combines the excitation and sensing advantages of unipolar pacing with the reliability of bipolar stimulation.

Arrhythmias, Cardiac↗
PubMed1975

Clinical applications of the threshold tracking pacemaker.

The concept of automatic threshold tracking is the most recent adaptation of artificial cardiac pacemakers to physiologic needs. Earlier pacemaker innovations were primarily in the area of timing of impulse delivery, whereas more recent changes have focused on alteration of the amplitude and duration of the pacemaker stimulus. Matching of this stimulus to the cardiac excitation threshold is important because a stimulus greater than necessary is wasteful of battery energy and may produce arrhythmias, whereas a stimulus of less than threshold intensity fails to pace the heart. Because of the wide range of clinically encountered threshold levels it is impossible to design a fixed output pacer that is efficient and safe for all patients at all times. The threshold tracking pacemaker searches for and finds the threshold level, and adjusts its stimulus to just above this level. The device ensures an adequate safety margin of stimulation, but reduces the stimulus level to the lowest safe level possible. It is fully automatic, adjusts immediately to any threshold changes and is not dependent on manual alteration.

Arrhythmias, Cardiac↗