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Biomedical subjects

E Harrison

Publications and source records attributed to E Harrison.

At least 19 recordsLinked to original sources
PubMed1991

Ventricular arrhythmias during treatment with alteplase (recombinant tissue plasminogen activator) in suspected acute myocardial infarction.

Continuous electrocardiography during the first 24 hours of a stay in a coronary care unit was used to record ventricular arrhythmias during treatment with alteplase (recombinant tissue plasminogen activator) or placebo. Recordings were made on 378 of the 436 patients admitted to a double blind trial of alteplase or placebo in one participating centre of the Anglo-Scandinavian study of early thrombosis (ASSET), patients being selected according to the availability of recorders. Of these, 309 (158 given alteplase and 151 placebo) had greater than 5 hours of analysable data. Most of the arrhythmias were recorded in patients with an in hospital diagnosis of myocardial infarction. Ventricular couplets and ventricular tachycardia were significantly more common in the patients treated with alteplase. Further, in patients with myocardial infarction who had ventricular extrasystoles, couplets, or ventricular tachycardia type a, the number of hours in which each arrhythmia was recorded was significantly higher in the alteplase group. The various ventricular arrhythmias in the alteplase group tended to cluster in the first 4-12 hours of the recordings. During the first 24 hours admission there were four episodes of ventricular fibrillation in the alteplase group and five in the placebo group of taped patients. By one month there had been 18 deaths in these 309 patients (alteplase four, placebo 14). These bore no relation to any recorded arrhythmia. Clinical records for the patients with no or minimal tape data yielded six further episodes of ventricular fibrillation during the first 24 hours (three in the alteplase group and three in the placebo group). Of the total 436 patients, 10 of the 218 patients in the alteplase group had died by one month compared with 22 of the 218 patients treated with placebo. The use of alteplase increases the incident of non-life threatening ventricular arrhythmias. These results, however suggest that arrhythmia after thrombolysis in the pre-hospital phase may be less of a problem than it is perceived to be.

Adolescent↗
PubMed1991

Post-prandial worsening of angina: all due to changes in cardiac output?

BACKGROUND: The precise mechanism leading to the post-prandial worsening of angina has yet to be adequately defined. It has been attributed to an increase in double product but is perhaps more likely to be related to an increase in cardiac output after food. This study was designed to evaluate the effects of food on patients' exercise tolerance and compare these with changes in haemodynamic variables. METHODS: 23 patients with chronic stable angina who had post-prandial worsening of their angina were studied. The patients were evaluated on two occasions and at each visit they underwent two symptom limited treadmill exercise tests. They remained fasting on the first visit and were given a 1400 kcal meal 60 minutes before the second exercise test on the second visit. Time to onset of 1 mm ST segment depression, heart rate, systemic arterial blood pressure, and cardiac output were measured at rest and during exercise. RESULTS: There were no differences in any of the variables during the two exercise tests on the day the patients remained fasting. After the meal exercise tolerance fell significantly by 136 seconds and the stage at which 1 mm ST segment depression was first seen was also significantly reduced. Resting cardiac output increased significantly by 0.86 1/min with the patients sitting and by 0.89 1/min standing. The exercise times after food were significantly related to cardiac output even when fasting times were taken into account. Resting heart rate increased significantly by 8.3 beats per minute sitting and 10.4 beats per minute standing. There was little change in blood pressure and no evidence that the double product predicted the post-prandial exercise time. CONCLUSIONS: Worsening of angina was related to the increase in cardiac output after a meal and successful treatment will depend upon the prevention of this increase.

Aged↗
PubMed1988

Does prolonged breastfeeding adversely affect a child's nutritional status?

In 202 children who visited a children's hospital in the city of Accra, Ghana, breastfeeding beyond the age of 19 months was found to be associated with malnutrition. The effect of weaning on food intake was then studied in 15 breastfed malnourished children in a rural community. Before weaning (complete cessation of breast-feeding) protein and energy intakes of all the malnourished children were about half those of 5 normal children. 10 of the malnourished children were weaned, and their intakes rose to the levels of the normal children; the 5 who continued breastfeeding maintained their low intakes. These results indicate that prolonged breastfeeding can reduce total food intake and thus predispose to malnutrition. They also suggest that in Ghana and other developing countries the proper weaning age may be about 18 months.

Age Factors↗
PubMed1986

Efficacy and safety of medium- and high-dose diltiazem alone and in combination with digoxin for control of heart rate at rest and during exercise in patients with chronic atrial fibrillation.

We evaluated the efficacy and the safety of medium-(240 mn/day) and high-dose (360 mg/day) diltiazem alone and in combination with digoxin when used for control of heart rate in 12 patients with chronic atrial fibrillation. Medium-dose diltiazem was comparable to therapeutic dose of digoxin at rest (88 +/- 19 vs 86 +/- 12 beats/min) but superior during peak exercise (154 +/- 23 vs 170 +/- 20 beats/min; p less than .05). High-dose diltiazem resulted in better control of heart rate than digoxin both at rest (79 +/- 17 beats/min; p less than .05) and exercise (136 +/- 25 beats/min; p less than .05) but was associated with side effects in 75% of the patients. Combined therapy of digoxin and diltiazem enhanced the effect of digoxin alone and resulted in significantly better control of heart rate at rest (67 +/- beats/min with medium-dose and 65 +/- beats/min with high-dose diltiazem) and during peak exercise (132 +/- 32 and 121 +/- 24 beats/min, respectively). However, the difference in heart rate between these two doses was not significant. Reduction of heart rate combined with concomitant effect on blood pressure resulted in a significant fall in pressure-rate product at rest from 10,077 +/- 1708 mm Hg/min on digoxin alone to 7877 +/- 1818 mm Hg/min after the addition of medium-dose diltiazem (p less than .05) and during exercise form 25,670 +/- 3606 to 18,439 +/- 4115 mm Hg/min (p less than .05). Continued therapy with digoxin combined with diltiazem 240 mg/day for 21 +/- 8 days in nine patients showed persistent effect on heart rate and blood pressure without any toxic manifestations or change in serum digoxin (1.5 +/- 0.4 vs 1.3 +/- 0.4 ng/ml) or plasma diltiazem concentrations (204 +/- 72 vs 232 +/- 129 ng/ml). In conclusion, medium-dose diltiazem when combined with digoxin is an effective and safe regimen for the treatment of patients with chronic atrial fibrillation and enhances digoxin-mediated control of heart rate both at rest and during exercise.

Adult↗
PubMed1986

Constant velocity dynamometer: an appraisal using mechanical loading.

Measurement characteristics of two constant velocity dynamometers (Cybex II, Lumex, Inc., NY) were evaluated at 11 selected speeds (0 to 5 rad X s-1) under various conditions of inert gravitational loading. A linear accelerometer was affixed to the lever arm. Speed settings were standardized percentages of each machine's maximum tachometer feedback voltage (0 to 100% Vfb max). Regression of Cybex transducer-observed voltages (V0) on true, i.e., expected, torques (Me) revealed that, for any static loading condition or angle, the measurement system was essentially linear and valid, although greater variance was evident for smaller torques. However, different calibrations, i.e., regression lines, were required for different speed settings. The error in predicting Me from V0 increased substantially with increased % Vfb max. Methodologies which assume constant velocity dynamic loading induce questionable, often invalid, results and inferences. Dynamic V0 represents both gravitational and inertial components. Considerable fluctuations in lever arm instantaneous velocity were ascribed to the combined influence of load and % Vfb max upon the servomotor. After computing inertia-corrected Me, calibration variability and prediction error were markedly reduced. Unexplained variability may be due to poor proximity of the Cybex transducer to the force application point. We concluded that: Cybex II should be calibrated only statically; use of an optimal filter will avoid false estimates of joint torque; inertial corrections must be applied in order to minimize potentially serious errors due to system angular acceleration; and reported muscle function relationships might be usefully re-assessed in view of these findings.

Biomechanical Phenomena↗
PubMed1984

Simple devices for the physically disabled.

A report is given on a number of devices for the disabled that have been developed in the Biomedical Engineering Department at the Mississippi Methodist Rehabilitation Center. The primary criteria used in selection of devices to be included use simplicity, ease of fabrication and low cost.

Automobile Driving↗
PubMed1984

Distancing for intimacy in lesbian relationships.

The authors present a collaborative treatment model designed to help the closely merged, troubled lesbian relationship. Therapeutic techniques focus on change in territorial, temporal, monetary, cognitive, emotional, and environmental space. A case example illustrates the interventions, which include individual and conjoint work, collaboration between therapists, education, bibliotherapy, referral to gay community resources, and specific suggestions for behavior change. The therapeutic goal is to restore intimacy to the relationship by offering each partner increased distance, personal space, and individual autonomy.

Adaptation, Psychological↗
PubMed1983

Mitral valve aneurysm: clinical features, echocardiographic-pathologic correlations.

Aneurysm of the mitral valve occurs most commonly in association with infective endocarditis of the aortic valve. The probable mechanism of its formation is destruction of the aortic valve which results in a regurgitant jet that strikes the anterior leaflet of the mitral valve, creating a secondary site of infection leading to the development of an aneurysm. Perforation of these aneurysms may occur, resulting in mitral regurgitation and pulmonary edema from a ventricle already volume overloaded from aortic regurgitation. This report describes the clinical and echocardiographic-pathologic findings in five patients with pathologically proven aneurysm of the mitral valve. There are no clinical features that appear specific for this abnormality. The two-dimensional echocardiographic feature that is helpful in the diagnosis is a bulge of the mitral valve leaflet toward the left atrium that persists throughout the cardiac cycle. Preoperative diagnosis is important because a mitral valve aneurysm may produce serious complications and is frequently overlooked during surgery. Repair of the aneurysm may be feasible; otherwise, valve replacement becomes necessary. Careful two-dimensional echocardiographic examination should be done in patients with left-sided infective endocarditis to detect an aneurysm of the mitral valve.

Adult↗
PubMed1979

Isolated chronic tricuspid insufficiency due to closed chest trauma: report of a case with long-term follow-up.

A case of isolated chronic tricuspid insufficiency due to closed chest trauma is described in this report. Studies for carcinoid syndrome were negative. At surgery the posterior leaflet of the tricuspid valve appeared to be torn and disrupted. The other leaflets were shortened and atrophic. The results of pre- and postoperative cardiac catheterization with long-term follow-up to the present, and the available literature on this rare entity has been briefly reviewed.

Aged↗
PubMed1978

Surgical management of the small aortic annulus. Hemodynamic evaluation.

Replacement of the aortic valve can be accomplished with ease and safety in most instances. The presence of a small aortic root, however, remains a problem in that both mechanical and stent-mounted tissue valves produce higher resting gradients in the smaller sizes. To avoid this, a technique has been developed to enlarge the aortic annulus. In a series of 253 patients undergoing aortic valve replacement, 22 required division of the aortic annulus. Extension of the incision inferiorly to the anterior leaflet of the mitral valve and a resulting separation of the annulus facilitated implantation of a larger valve. The resulting defect is obliterated with a woven Dacron patch. Hemodynamic data obtained on 12 patients who had recatheterization one to ten months postoperatively disclosed an average resting transvalvular gradient of 13.5 mm Hg. This procedure has been used successfully in combined aortic and mitral valve replacement and heart block has not occurred. Based upon encouraging follow-up studies of the Hancock glutaraldehyde-stabilized porcine heterograft, we use this prosthesis in patients with annular diameters of less than 25 mm. Our experience suggests that enlargement of the aortic annulus is necessary in a significant number of patients undergoing aortic valve replacement.

Animals↗