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Biomedical subjects

D H Bennett

Publications and source records attributed to D H Bennett.

At least 19 recordsLinked to original sources
PubMed1992

Reduction of radiation exposure to the cardiologist during coronary angiography by the use of a remotely controlled mechanical pump for injection of contrast medium.

Selective coronary cineangiography was carried out in 103 consecutive patients. In half the examinations (53) injection of contrast medium was performed by hand using a syringe, with the cardiologist standing in the usual position next to the X-ray table. In the other half (50) contrast medium was injected by a remotely controlled mechanical pump whilst the cardiologist stood well away from the X-ray source. Radiation dose to the lens of the cardiologists eye was estimated for the two groups by measurement of head badge dosimetry. In the first group (hand injection) total radiation dose was 1.30 mSv; in the second group (mechanical injection) it was reduced five-fold, to 0.25 mSv. This technique therefore represents an important means of achieving substantial reductions in radiation exposure to cardiologists.

Cineangiography↗
PubMed1992

Acute and chronic performance of a steroid eluting electrode for ventricular pacing.

Studies have demonstrated consistently low stimulation thresholds in the first months following implantation of steroid eluting electrodes. There have been no reported cases of exit block. There is little information on the long-term performance of these leads. Data were collected on 15 patients in whom Medtronic steroid eluting leads (5023 and 4003) had been implanted in 1987. Stimulation thresholds were measured at implantation and at weeks 1, 2, 3, 4, 5, 6 and 12. Stimulation threshold, lead impedance and sensing thresholds were monitored periodically for 3 yr using the telemetered function of the pulse generator. Three-month follow-up was obtained in all the patients and 3-yr follow-up in 10. Stimulation thresholds remained low throughout the follow-up period in all but one patient who developed exit block necessitating the replacement of the pacing system. In the remaining patients there was a significant increase in mean stimulation threshold from implantation to week 1 (mean stimulation threshold at implantation = 0.106 ms, mean ST at week 1 = 0.182 ms; p = 0.05), and also a gradual increase in the stimulation threshold over the first 2 yr of follow up (mean stimulation threshold 1 week = 0.182 ms, mean stimulation threshold months 13-24 = 0.243 ms; p = 0.05). Lead impedance showed no significant change over the follow-up period (mean change in impedance = 4.3 omega, SD 163.2, p = 0.97). Unlike many conventional electrodes, steroid eluting leads show no early peak in stimulation threshold but exit block can occur. Stimulation thresholds show a small but significant rise over time.

Atrial Fibrillation↗
PubMed1992

Atrial latency in a dual chambered pacing system causing inappropriate sequence of cardiac chamber activation.

A transvenous atrioventricular pacemaker was implanted in a patient in whom junctional bradycardia and recurrent ventricular tachycardia had occurred after coronary artery bypass surgery. The period between delivery of the atrial stimulus and resultant atrial excitation was prolonged by up to 0.22 seconds and exceeded the programmed delay between atrial and ventricular stimulation. Consequently, ventricular stimulation preceded atrial excitation. Cardiac failure resulted: it was resolved by reprogramming the pacemaker to the atrial inhibited mode.

Atrial Function↗
PubMed1992

[What must the community contribute to the managements of chronic psychiatric patients?--Reflections from England].

Chronically disabled psychiatric patients who are living outside hospital still need help. The degree of disability they show and the support which they receive from family or friends differs greatly. How they manage will depend on their ability to adapt and one can recognize the difference between those who adapt well in spite of disability and those for whom this is very difficult. In consequence their need for support from others varies. In England some national voluntary agencies traditionally offer support. However, today the combined work of voluntary organisations, hospitals and statutory community authorities in local areas is often impressive and two examples are described. Even so families are perhaps still the most important form of support although some are unable or unwilling to help. Other alternative forms of help noted are two-patient marriages, long-term hospital support of discharged patients and regular employment. Examples of innovations in Australia and the U.S.A. are also described.

Chronic Disease↗
PubMed1991

Paucity of risk factors in women with angina and normal coronary angiograms.

A significant proportion of women who undergo coronary arteriography for investigation of angina have normal coronary angiograms. We wanted to test the hypothesis that screening women with risk factors for coronary arterial disease would reduce the need for subjecting them to this invasive procedure. Comparisons were made between 100 women with normal coronary angiograms and 100 women with angiographic evidence of coronary arterial disease. Both groups had presented with angina and had undergone coronary angiography in 1985 or 1986. Women with angina and normal coronary angiograms had fewer risk factors than those with coronary arterial disease. They were younger (mean 49.0 and 55.9 years, respectively), had less severe angina on presentation (atypical or mild angina: 35% vs 16%), were less likely to have a family history of myocardial infarction (12% vs 53%), were more likely to have never smoked cigarettes (64% vs 13%), and fewer of them had a serum cholesterol in excess of 6 mmol/l (36% vs 64%). Five independent predictors of coronary arterial disease were identified; family history, myocardial infarction, age, hypertension and smoking habit. No women with angina and abnormal coronary angiograms were found to be free of risk factors, whereas 42% of women with angina and normal coronary angiogram were free of risk factors. The data suggests that coronary angiography will probably be normal in women with angina who are free of risk factors.

Adult↗
PubMed1991

Desirability of immediate surgical standby for coronary angioplasty.

OBJECTIVE: To assess the value of emergency surgical standby for percutaneous transluminal coronary angioplasty. DESIGN: Retrospective review of the major complications of coronary angioplasty in a regional cardiac centre. SETTING: All angioplasties were performed in the cardiac catheterisation laboratory of Wythenshawe Hospital with surgical standby in an adjoining operating theatre. PATIENTS: 1262 vessels were dilated in 1032 patients (mean age 53 years) between 1984 and 1989. MAIN OUTCOME MEASURES: In-hospital mortality from emergency surgical revascularisation after angioplasty; the rate of myocardial infarction and overall morbidity. RESULTS: Coronary angioplasty achieved primary success in 90% of cases. Thirty eight (3.7%) patients (five women (mean age 55.8) and 33 men (mean age 53.0] were referred for urgent surgical revascularisation--36 direct to operation and two within 24 hours. All patients survived surgery. Five of the 38 had had a previous angioplasty to the same vessel and one had had previous coronary artery grafts. Four of the 38 had an angioplasty for unstable angina. Eighteen had single, 13 double, and seven triple vessel coronary artery disease. The target vessel was the left anterior descending in 25, right coronary artery in nine, circumflex in three, and the left anterior descending and circumflex coronary arteries in one. Five required external cardiac massage on the way to the operating theatre; two of them had a left main stem occlusion. Four internal mammary artery and 60 reversed saphenous vein grafts were implanted (1.6 per patient). Complete revascularisation was achieved in 36 (94.7%) patients. Q wave myocardial infarction occurred in six (15.8%). The final outcome was: none dead, three patients with angina, one late death, one cerebrovascular accident, one late operation for a new left anterior descending lesion, two patients on diuretics with or without an angiotensin converting enzyme inhibitor. One orthotopic transplant was performed in a patient in whom cardiogenic shock developed after the left anterior descending coronary artery became occluded 72 hours after angioplasty. CONCLUSION: There was no surgical mortality and low morbidity among patients for whom immediate surgical cover was requested.

Angioplasty, Balloon, Coronary↗
PubMed1978

Identical twins with differing forms of ventricular pre-excitation.

Identical 10-year-old twins, both with electrocardiograms showing a short PR interval and a normal QRS complex but with dramatically different electrophysiological characteristics, are described. One twin experienced episodes of rapid palpitation and on one occasion was resuscitated from ventricular fibrillation. An intracardiac electrophysiological study confirmed the presence of an atrioventricular nodal bypass tract and in addition revealed the presence of an accessory atrioventricular pathway, thus demonstrating that the patient had both the Lown-Ganong-Levine and Wolff-Parkinson-White syndromes. Re-entry tachycardia and atrial fibrillation, with a very rapid ventricular rate, were precipitated. After treatment with amiodarone, the patient became asymptomatic and a repeat study showed that the features of the atrioventricular nodal bypass tract were no longer present and though re-entry tachycardias using the accessory atrioventricular pathway could still be induced, their rates were slower than before treatment. The other twin, in spite of an identical surface electrocardiogram, was asmymptomatic. An electrophysiological study showed the features of an atrioventricular nodal bypass tract but there was no evidence of additional atrioventricular accessory connections and a tachycardia could not be induced.

Amiodarone↗
PubMed1978

Social deviance in a day hospital.

A search was made of records available for 65 nonpsychotic patients referred to a psychiatric day hospital. Assessments were made of whether they had shown various specified types of deviant social conduct, such detailed objective surveys of social conduct being regarded as superior to the use of concepts such as "psychopathic personality". The correlational structures of the areas of deviance produced four factors, i.e. deviant family roles, poor social integration, violence, and a more heterogeneous antisocial behaviour factor. The relationship was examined between areas of deviance and indices of the course and outcome of day hospital admission. The prognostic significance of social deviance was different for men and women; for example, only men showed a correlation between the number of areas of social deviance and the outcome of day hospital admissions. Violence and poor social integration showed no relation to outcome at all. It is suggested that there is no basis for excluding such patients from day hospitals on the assumption that they are less likely to be helped than other non-psychotic patients.

Antisocial Personality Disorder↗
PubMed1978

Disopyramide in patients with the Wolff-Parkinson-White syndrome and atrial fibrillation.

The effect of administration of disopyramide on the ventricular response to atrial fibrillation was studied in six patients with the Wolff-Parkinson-White syndrome. The drug was given intravenously to five patients during intracardiac electrophysiologic studies and to a sixth patient during electrocardiographic monitoring in a coronary care unit. One patient with a very rapid ventricular response to atrial fibrillation underwent a second electrophysiologic study after oral treatment for four weeks with disopyramide. In all cases, administration of disopyramide reduced the mean ventricular rate and increased the shortest interval between consecutive preexcited ventricular complexes during atrial fibrillation. Therapy with disopyramide should therefore be useful in preventing ventricular fibrillation which can result from a rapid ventricular response to atrial fibrillation in patients with an accessory atrioventricular pathway. There has been no recurrence of paroxysmal tachycardia in the four patients who have been maintained on oral therapy with disopyramide.

Adult↗
PubMed1977

Previous occupational stability as a predictor of employment after psychiatric rehabilitation.

Several indices of occupational stability are discussed and the importance of controlling for age in assessing occupational stability emphasized. The ability of 6 indices to predict the stable resettlement of psychiatric patients at work after a course of rehabilitation was examined. Though mean job length was a significant predictor, indices based on change of occupation rather than change of job were more successful. Stable resettlement at work was related to how much time people had spent in long jobs but not to how little time they had spent in short jobs. The amount of unemployment during the 2 years before hospital admission predicted return to work immediately after discharge, but did not predict stable resettlement at work.

Age Factors↗
PubMed1977

Valvar aortic stenosis with unusual features.

This case report documents the co-existence of valvar aortic stenosis and hypertrophic obstructive cardiomyopathy with systemic hypertension and calcific mitral annulus, a combination which has not hitherto been reported. It is the purpose of this paper to help assess the true incidence of the co-existence of aortic stenosis and hypertrophic cardiomyopathy.

Aged↗
PubMed1977

Effects of instructions, biofeedback, and cognitive activities on heart rate control.

In a factorial experiment, 90 male and 90 female subjects were given (a) either instructions to increase heart rate (HR), decrease HR, or no instructions to change their HR; (b) either true biofeedback, false biofeedback, or no biofeedback; and (c) either instructions concerning cognitions to help them change HR or no instructions concerning cognitions. The results indicated that (a) for increasing HR, instructions to increase HR were as effective as the combination of instructions and true biofeedback; (b) for decreasing HR, neither instructions nor biofeedback nor the combination of instructions and biofeedback was more effective than simply sitting quietly; (c) although subjects instructed to increase HR showed higher HRs at the end of training than subjects instructed to decrease, the increase subjects showed a decline in HR from the initial period; (d) almost all subjects reported using cognitions to influence HR, and instructions concerning the use of cognitions did not facilitate changes in HR; and (e) women showed higher HRs, which declined more slowly than those of men, but sex did not interact with any treatment variable. It was concluded that increases (or retarded decreases) in HR were due to instructions, and decreases were due to simple adaptation, thus raising serious questions concerning the effectiveness of the biofeedback component of "biofeedback training" for altering HR.

Biofeedback, Psychology↗
PubMed1976

Echocardiographic assessment of mitral valve calcification.

The mitral valve was assessed by echocardiography in 20 patients, aged 27 to 67 years, who subsequently underwent mitral valve replacement. After removal, the mitral valve cusps were examined by direct measurement, radiography, and quantitative calcium extraction. Increased thickness of the E-F echo was found where calcification or fibrosis was present, differentiation by echocardiography alone being unreliable. However, multiple dense parallel E-F echoes were found in all 10 patients with more than 80 milligrammes of calcium in the valve, while a single thin E-F echo indicated the absence of significant calcification or fibrosis.

Adult↗
PubMed1976

Test of reliability of echocardiographic estimation of left ventricular dimensions and volumes.

This test is based on the incompressibility of myocardium, which dictates that left ventricular wall volume remains constant throughout the cardiac cycle. The volumes occupied by the left ventricular cavity, by ventricular wall plus cavity, and hence by ventricular wall alone were estimated, both at end-systole and at end-diastole, from ecocardiographic measurements of cavity transverse dimension and wall thickness. Wall volumes were determined by assuming an ellipsoid shape (the major axis being predicted from aggression equations relating angiocardiographic and echocardiographic cavity dimensions) and also by the cube method. A discrepancy between systolic and diastolic wall volume estimates indicates either that the measurements of ventricular dimensions were unreliable or that the assumptions of ventricular geometry involved in the volume calculations were incorrect. Studies were made on 60 subjects. Using the ellipsoid formula, values for wall volume ranged from 66 to 719 ml; systolic and diastolic wall volumes correlated closely (r = 0-96, mean difference = 6-8 +/- 0-9 (SEM) %) supporting the reliability of the echocardiographic dimensions and estimates of cavity and wall volume. In the 12 patients with very large end-diastolic cavity transverse dimensions (6-5 to 8-6 cm) however, correlation was less good (r - 0-81, mean difference = 14-3 +/- 2-3 (SEM) 5). Using the cube method, which does not allow for the changing relation between minor and major cavity axes with increasing cavity size, wall volumes were greater (76 to 986 ml) but correlation was similar (r = 0-94, mean difference = 7-1 +/- 0-9 (SEM)%). Having established that it is possible to obtain close agreement between wall volumes determined at different points in the cardiac cycle, this test can be used to assess the reliability of echocardiographic left ventricular dimensions and volume estimates in individual subjects.

Adolescent↗
PubMed1975

Influence of denial (situation redefinition) and projection on anxiety associated with threat to self-esteem.

Subjects in a threat condition were informed that they had failed an important test while subjects in a nonthreat condition were not told that they had failed. To manipulate the use and timing of coping strategies for dealing with threat, subjects were told to (a) redefine the nature and importance of the test before receiving feedback, (b) redefine the nature and importance of the test after feedback, or (c) estimate the performance of their friends on the test (i.e., project) after receiving feedback. Repeated measures of subjective anxiety and pulse rate indicated that (a) the threat manipulation was effective in increasing stress, (b) redefinition occurring before the onset of threat was effective in eliminating stress, and (c) redefinition occuring after the onset of threat was ineffective in reducing stress. Projection reduced the report of subjective anxiety. The results revealed factors that influence coping strategy effectiveness and resolved conflicts in previous findings.

Adolescent↗