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Biomedical subjects

R M Boyle

Publications and source records attributed to R M Boyle.

At least 37 records · Page 2Linked to original sources
PubMed1988

Comparison between manual and computer measurement of ST-segment amplitude during exercise.

Several studies have shown that the maximal ST/HR slope may be used as a reliable index of myocardial ischemia as assessed by coronary angiography, but this involves laborious training and derivation, particularly with respect to the measurement of ST segment amplitude, which is obtained by averaging values measured in at least 10 cardiac cycles in the steady state. The authors compared manual measurement of ST-segment amplitude with computer-processed beat using cardiac cycles in six consecutive patients with standard 12-lead records obtained over 5 seconds and a beat processed by the recorder to represent each lead (modal beat, over 10 seconds). All recordings were made in the steady state. Two patients had myocardial ischemia, as assessed by means including the maximal ST/HR slope and the occurrence of ST-segment depression at the end of exercise. Comparisons were made between measurements in 324 pairs of ST-segment amplitude obtained, respectively, from manually averaged recorded beats (average beat) and the modal beat during each step of the exercise test. The level of the ST-segment, (80 msec after the end of QRS complex) was independently obtained from the two records in a blinded fashion. The group data showed that the modal beat gave significantly lower values of ST-segment amplitude than the average beat. Similar results were obtained when 286 pairs of positive amplitudes were compared in the range of 0-7.25 mm. In the remaining 38 pairs in which ST-segment depression was found, the amplitude in the modal beats was not significantly different from the average beats.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Changes in myocardial ischaemia during isosorbide dinitrate or indoramin therapy in patients with stable angina using relations between the ST segment and heart rate.

The effect of isosorbide dinitrate or indoramin on myocardial ischaemia was examined in patients with stable angina pectoris. In a prospective trial, randomization resulted in 8 and 9 patients, respectively, given isosorbide dinitrate in a dose of 30-90 mg daily, and indoramin in a dose of 75-225 mg daily; 2 of these patients were serially examined during the two types of therapy. Changes in myocardial ischaemia were assessed by exercise testing using 12 standard electrocardiographic leads and a bipolar lead CM5. Individual and group comparisons showed that isosorbide dinitrate resulted in an increase in ST segment depression, the maximal ST/heart rate slope and the ratio of net ST segment depression to increases in heart rate (at least P less than 0.01). In contrast, with indoramin therapy there were no significant changes in these indices. The results in these patients suggest that isosorbide dinitrate leads more consistently to increases in the severity of myocardial ischaemia than indoramin, although this effect on ischaemia is apparently less than the benefit of these agents on exercise performance.

Adult↗
PubMed1988

Aortic valve disease and the ST segment/heart rate relationship: a longitudinal study before and after aortic valve replacement.

The ST segment/heart rate relationship or maximal ST/HR slope has been validated as an index of myocardial ischemia in selected populations of patients with angina pectoris. The present study involved patients selected as having aortic valve disease unaccompanied by angiographic coronary artery narrowing. In each of seven patients, so far examined, a slope value and ST segment depression of greater than 1 mm were obtained which, according to previous experience, indicated myocardial ischemia equivalent to coronary heart disease. After aortic valve replacement, there was a significant reduction in heart size as assessed using the cardiothoracic ratio, and the amplitude of QRS complex on the electrocardiogram. The slope was abolished (two patients) or markedly reduced (five patients), and the decrease in the seven patients was statistically significant. ST segment depression could be obtained in one patient. This study has shown the occurrence of maximal ST/HR slope in patients without large coronary artery disease who have aortic valve disease and cardiac enlargement.

Aortic Valve↗
PubMed1987

Use of the maximal ST/HR slope to estimate myocardial ischaemia after recent myocardial infarction.

Fifty two patients were examined 4-6 weeks after myocardial infarction to assess whether factors other than coronary artery narrowing affect the maximal ST/HR slope which is used as an index of myocardial ischaemia. The slope was compared with indices of myocardial scarring or cardiac enlargement derived from x ray and echocardiographic and angio-cardiographic investigations. In 35 (67%) patients the slope failed to predict the severity of myocardial ischaemia attributable to coronary artery narrowing: in 14 (27%) patients the slope overestimated the findings of coronary angiography and in 21 (40%) patients the slope underestimated the findings of coronary angiography. In the remaining 17 (33%) patients the slope accorded with the assessment of myocardial ischaemia by coronary angiography. Underestimation by the slope was associated with significantly poorer left ventricular function and a lower ejection fraction, indicating a greater degree of myocardial scarring. To assess whether overestimation was related to cardiac enlargement with better preservation of ventricular function a follow up examination was performed six months after infarction. In the overestimated group 11 patients were followed up and seven of them showed a reduction in the maximal ST/HR slope which correlated with a reduction in the cardiothoracic ratio. This suggested that cardiac enlargement had contributed to myocardial ischaemia. The results suggest that if the maximal ST/HR slope is an index of exercise induced myocardial ischaemia after recent infarction, it is subject to the influences of coronary artery narrowing as well as those of scarring and cardiac enlargement.

Adult↗
PubMed1987

Diagnostic value of the maximal ST segment/heart rate slope in asymptomatic factory populations.

In Leeds in hospital populations of patients with angina the maximal ST/HR slope was found to be a reliable index of myocardial ischemia as assessed by coronary angiography. Subsequent studies in Leeds and elsewhere in populations of patients with cardiac enlargement or following myocardial infarction have shown that the slope is affected by myocardial scarring, ventricular enlargement and aneurysm. These findings implied that the slope had features in common with other usual exercise tests; studies in Leeds and elsewhere, however, have shown a superior diagnostic reliability using the maximal ST/HR slope in patients with angina. The present report involves the use of the slope in asymptomatic populations. Trials are being undertaken in two factory populations, which respectively comprised all volunteers or asymptomatic men over the age of 30 who were randomly chosen by computer. Subjects with slope values indicating, according to previous experience, myocardial ischemia equivalent to coronary heart disease were referred for cardiological investigations which included angiocardiography; blind comparisons were performed between results of investigations and the slope. So far 1194 subjects have been examined. In 68 subjects the maximal ST/HR slope indicated myocardial ischemia, and in 24 of these cardiological investigations were completed. In nine of the 24 subjects the slope corresponded to the number of significantly narrowed coronary arteries (greater than 75% reduction in luminal diameter); in 12 of the remaining 15 subjects who had no coronary narrowing, there were cardiac lesions which included cardiac enlargement, aortic valve disease, myocarditis, pericarditis, myocardial bridging and conduction defects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Acetylsalicylic acid and dipyridamole improve the early patency of aorta-coronary bypass grafts. A double-blind, placebo-controlled, randomized trial.

A total of 125 patients undergoing aorta-coronary bypass grafting for disabling angina were randomized to receive either 330 mg of acetylsalicylic acid (aspirin) plus 75 mg of dipyridamole three times daily or a placebo for 6 months postoperatively. In addition, all patients were given warfarin for 3 months. Repeat angiography was performed at 6 months in 103 patients. In the treatment group 95 grafts were implanted in 48 patients, of which 87 were patent (91.6% patency rate). This figure compares with 88 grafts patent out of 118 implanted in 55 patients in the placebo group (74.6% patency rate) (p less than 0.01). We conclude that antiplatelet therapy improves the early patency of saphenous vein aorta-coronary bypass grafts.

Adult↗
PubMed1984

Assessment of aortocoronary bypass grafting using exercise ST segment/heart rate relation.

The maximal rate of progression of ST segment depression relative to increases in heart rate (maximal ST/HR slope) has recently been shown to be an accurate index of the presence and the severity of coronary heart disease in patients with angina. The value of this new exercise test was assessed in patients undergoing aortocoronary bypass. The maximal ST/HR slope and the results of coronary angiography were obtained in each of 46 patients before aortocoronary bypass surgery and in 26 of the 46 patients six months after the operation. At each stage of the investigation the maximal ST/HR slope detected without false results the absence and the number of significantly diseased vessels as shown by angiocardiography. As in previous findings the ranges of the maximal ST/HR slope showed no overlap between the four groups of patients: those with no significant disease and those with single, double, or triple vessel disease. In each of the 46 patients in whom the maximal ST/HR slope was determined before operation and three months afterwards the slope was lower after operation than before, indicating improvement. Follow up examinations showed that the maximal ST/HR slopes accurately detected the number of patent grafts used to bypass significantly diseased coronary arteries. Furthermore, the development of a significant narrowing or occlusion in any vein graft caused an increase in the maximal ST/HR slope which was equivalent to the value of single vessel disease. It is suggested that the maximal ST/HR slope may be used reliably in individual patients to indicate restoration of adequate blood supply to the myocardium after successfully aortorcoronary bypass surgery and the to detect in the period of six months after the operation the degree of severity of coronary heart disease whether it is caused by occlusion of the graft of significant disease of the coronary arteries.

Adult↗
PubMed1983

A comparison of once and twice daily atenolol for angina pectoris.

We have studied the effects of four doses of atenolol in 11 patients with stable angina pectoris using a symptom-limited exercise test and angina diaries. The doses 100 mg twice daily and 50 mg, 100 mg and 200 mg once daily were given double-blind and randomised within patients following run-in on placebo. Measurements were made 12 hours after the last twice daily dose and 24 hours after the last once daily dose. Exercise tolerance was improved by 40-74% and exercise duration before the onset of angina by 61-94% (P less than 0.01). Maximal heart rate was reduced further by a total daily dose of 200 mg than by lower doses, but no extra benefit was derived by giving the drug twice daily. The largest increase in exercise tolerance was obtained during treatment with 50 mg once daily. Atenolol was shown to be an effective anti-anginal agent when given once daily, and there were no major differences between the doses studied.

Adult↗
PubMed1981

Clinical cardiovascular experiences with iopamidol: a new non-ionic contrast medium.

Iopamidol, a new non-ionic water-soluble contrast medium, has been compared with standard ionic media in a number of cardiovascular applications. It is stable in aqueous solution, is much less viscous and only slightly more osmolar than metrizamide. Compared to sodium meglumine diatrizoate in a series of 40 coronary arteriograms, it produced a consistent and highly significant decrease in the incidence and severity of hypotension and bradycardia following intracoronary injection. In the same group and in 62 children undergoing ventricular or great vessel angiocardiography, a subjective assessment of patient reaction showed that iopamidol was better tolerated than the ionic medium. There was a very strong patient preference for iopamidol in a group of 20 of the adult patients who had also consented to femoral artery injections of both media. Throughout these series there was no detectable difference in arterial image quality between the media. Venous phase opacification during arterioportography was assessed in 11 cases comparing iopamidol with sodium meglumine iothalamate. No significant difference was found. We conclude that iopamidol is clearly preferable to ionic media for routine cardiovascular applications.

Angiocardiography↗
PubMed1981

A conversion code from ICHPPC-1 to ICHPPC-2.

Faculty members from four departments of family medicine participated in the production of a definitive conversion from the first to the second versions of the International Classification of Health Problems in Primary Care (ICHPPC). A detailed conversion code with the appropriate ICHPPC-2 equivalent for each ICHPPC-1 diagnostic title is provided. Differences between the two classifications are discussed and suggestions are made for the use of the conversion code.

Disease↗
PubMed1981

Accuracy of the patient identifier in a family practice data system.

The accuracy of a general practice data system has been measured and has improved considerably over three years. It is difficult to identify all the factors contributing to this change, but an overall effort to emphasize the importance of recording patient identifiers correctly has been effective. No directly comparable error rates have been reported elsewhere; consequently, relative accuracy cannot be known. Administrators and managers of data systems are urged to determine levels of error and disseminate this information.

Family Practice↗
PubMed1981

Exercise testing in ischaemic heart disease.

The exercise test may be regarded as an objective measure of functional capacity and a useful adjunct to the history given by the patient. As a means of diagnosis it has many limitations but a positive result in a male patient provides good corroborative evidence for the presence of coronary artery disease. As a means of predicting severity of disease the test remains imperfect but may prove useful with further refinements. The exercise test is of little value for screening except in special circumstances.

Arrhythmias, Cardiac↗
PubMed1980

Adding information and intelligence to a family practice data system.

A critical test of any data system is its relevance; more simply, reports must present what users want. At MCV, the current system is a direct response to expressed user demands (corroborated by results of a survey of British general practitioners). That is, resident and physicians are interested in workload rates, such as visits/patient, and a delineation of diagnoses by frequency. Applications of these reports are organizational, comparative, and educational. The ultimate goal of data systems in family practice is the production of intelligence about health and health affairs: clearly, this is valuable in patient care, research, and education. Methods outlined above will contribute to achieving this end by adding information and intelligence to data systems.

Data Collection↗