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Biomedical subjects

P M Cashman

Publications and source records attributed to P M Cashman.

10 recordsLinked to original sources
PubMed1992

Spontaneous variability of left ventricular ejection fraction assessed with the Cardioscint.

A miniature, non-imaging caesium iodide nuclear probe optically coupled to a photodiode (the 'Cardioscint') has been developed which, in conjunction with a modified personal computer, is capable of continuous on-line monitoring of left ventricular function and ST-segment level at the bedside. The purpose of this study was to assess the variability in ejection fraction over periods of time and to compare this variability with that of equilibrium gamma camera radionuclide ventriculography. Ten normal volunteers (nine male) of mean (S.D.) age 49 (10) years underwent semisupine radionuclide ventriculography using both gamma camera and Cardioscint in randomized order. The gamma camera recorded four consecutive acquisitions (mean of 7.2 min each) and the Cardioscint, using a 20 s acquisition time, recorded left ventricular function over 35 min per subject. The mean ejection fraction of the group by gamma camera was 52 (7)% and by Cardioscint was 54 (5)%. When the variability in ejection fraction by gamma camera was compared with the Cardioscint averaged over corresponding time periods (i.e. an average of 7.2 min), the mean coefficient of variation of the camera was 5.0% versus 2.9% for the probe system. Individual 20-s probe acquisitions over the total study duration (reflecting the short-term variability of the system) had a coefficient of variation of 5.1%. Thus the Cardioscint provides a stable continuous recording of ejection fraction. These volunteer data provide a basis for interpretation of data acquired in the clinical situation.

Adult↗
PubMed1978

Study of untreated hypertensive subjects by means of continuous intra-arterial blood pressure recordings.

Continuous recording of intra-arterial blood pressure and electrocardiograms has been performed in 41 ambulant untreated essential hypertensive subjects for periods up to 48 hours. Statistical analysis of the results has revealed: (1) A group of patients who developed a persistent tachycardia during the day. This response was not observed in a control population free of overt cardiovascular disease. (2) Three different haemodynamic responses to day-time activities suggesting different mechanisms for the production of high blood pressures. No normal controls are available for these changes. (3) No differences in responses between patients defined as 'labile' and 'fixed' hypertensives.

Adult↗
PubMed1978

Ambulatory electrocardiography in car workers.

A previous study in a car assembly plant showed that production-line workers had a lower incidence rate of heart attacks than executive staff. In the present study some major coronary risk factors and 24-hour ambulatory electrocardiograms were investigated in two age-matched samples of 30 middle-aged men drawn from these occupations. Men with a known history of heart disease were excluded. Compared with production-line workers, executive staff on average had a higher diastolic blood pressure (P less than 0.05) and fewer took heavy exercise during their leisure time (P less than 0.05). Ventricular premature beats (VPB was also similar for each of the periods of work, leisure and sleep. Apart from isolated ectopic beats, disturbances of rhythm were uncommon, and neither VPB nor other arrhythmias appeared to be induced by occupational factors.

Adult↗
PubMed1977

The use of R-R interval and difference histograms in classifying disorders of sinus rhythm.

A data reduction technique is presented which enables the patterns of cardiac rhythm inherent in a long-term ECG recording to be described in a concise fashion. The method consists in combining an R-R interval difference histogram, which gives information about the detailed structure of cardiac rhythm patterns, with an R-R interval histogram, which concisely describes the trends in heart rate over a period. Example of the histogram patterns corresponding to some common cardiac rhythms are presented. The histograms can be treated mathematically to yield information which is useful in assessing the long-term effects of drugs and in classifying disorders of cardiac rhythm.

Arrhythmia, Sinus↗
PubMed1975

Ambulatory electrocardiographic records in patients with transient cerebral attacks or palpitation.

Continuous electrocardiographic (ECG) records were made over 24 hours in 130 ambulant outpatients complaining of syncope, dizzy turns, or palpitation. In all these patients resting ECGs had failed to show significant dysrhythmias. Exercise testing was performed on 64 patients and also failed to reveal any dysrhythmias. Analysis of the tape recordings, however, showed appreciable dysrhythmias in 74% of the group. In most cases the dysrhythmias were complex mixtures of rapid supraventricular and ventricular rhythms. bouts of ventricular tachycardia were seen in seven patients, all of whom were women. Episodic complete heart block was seen in only two patients, but prolonged ventricular gaps (greater than 1-5 s), not associated with ectopic beats, were found in 26. No episodes of ventricular fibrillation were recorded. We conclude that many patients with vague symptoms suggestive of transient cerebral ischaemia or irregular heart action have significant and often dangerous dysrhythmias which can be diagnosed only by long-term recording of the ECG under fully ambulant conditions.

Adolescent↗