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N A Boon

Publications and source records attributed to N A Boon.

6 recordsLinked to original sources
PubMed1992

Early vasodilator treatment in myocardial infarction: appropriate for the majority or minority?

OBJECTIVE: To assess the influence of vasodilator treatment started early after myocardial infarction on left ventricular size and function. SETTING: Coronary care unit, Royal Infirmary, Edinburgh. PATIENTS: 105 patients with acute myocardial infarction (systolic blood pressure > 90 mm Hg) were randomised within 24 hours of the start of pain. Unlike previous studies 88% of the patients received thrombolysis. METHODS: Double blind randomised placebo controlled study with either 12.5 mg of captopril three times daily or 20 mg of isosorbide mononitrate three times daily for 28 days. MAIN OUTCOME MEASURES: Clinical outcome and left ventricular size and function assessed by echocardiography, radionuclide ventriculography, and magnetic resonance imaging. RESULTS: There was no difference in left ventricular size or function in either treatment group as measured one week after the end of the trial. Even the placebo group tended to decrease left ventricular diameter over the four week study period (one week: 5.0 (0.1) v, five weeks: 4.8 (0.1) cm, NS). Four patients had an adverse clinical outcome in the placebo group whereas no adverse outcome was seen in the captopril group. CONCLUSIONS: Vasodilator treatment may be of limited value or of no benefit for most infarct patients, particularly those treated with thrombolytic agents. Captopril, however, may benefit patients at high risk.

Captopril↗
PubMed1992

Myocardial dysfunction in patients infected with HIV: prevalence and risk factors.

OBJECTIVES: To determine the prevalence of and risk factors for myocardial dysfunction in HIV infection. SUBJECTS: 173 patients infected with HIV underwent echocardiography. 119 were current or previous injection drug users, 38 were homosexuals, 10 were haemophiliac patients, and six were heterosexual. MAIN OUTCOME MEASURE: Detection of impaired ventricular function. RESULTS: 26 patients with abnormalities of ventricular size or function or both were identified. The abnormality was (a) dilated cardiomyopathy in 13 patients (eight homosexuals, three drug users, and two haemophiliacs) with a mean CD4 count of 38 cells/mm3, which accords with end-stage disease (in addition, three patients were identified as having borderline impairment of left ventricular function); (b) left ventricular dilatation without loss of function in a further six patients; and (c) isolated right ventricular dilation in seven patients. Follow up echocardiograms were obtained in 71 patients, 18 of whom had myocardial dysfunction (103 echocardiograms, mean (SD) 2.5 (0.6) scans per patient, mean interval 200 (116) days, range 14-538 days). These showed that in four cases of isolated right ventricular dilatation, one of isolated left ventricular dilatation, and two with borderline left ventricular dysfunction myocardial function subsequently reverted to normal. There was no excess of exposure to zidovudine in the patients with myocardial dysfunction. Similarly, patients with myocardial dysfunction had no serological evidence of excess secondary infection with Toxoplasma gondii and cytomegalovirus. CONCLUSIONS: There was a high prevalence and wide range of myocardial dysfunction in HIV positive patients. Dilated cardiomyopathy was a feature of advanced HIV disease and affected all major risk groups for HIV infection. In contrast, isolated dilatation of either ventricle occurred at an earlier stage of HIV infection and, particularly in the case of the right ventricle, often was transient. Neither treatment with zidovudine nor infection with Toxoplasma gondii or cytomegalovirus seemed to be responsible for these findings.

Adult↗
PubMed1990

Atrial pacing: who do we pace and what do we expect? Experiences with 100 atrial pacemakers.

The records of 100 patients with permanent atrial pacemakers implanted over a 7-year period were reviewed to assess the role and results of this mode of pacing. Indications for pacing were sick sinus syndrome in 91, carotid sinus hypersensitivity in 3, and use of an antitachycardia device in 6 patients. The mean follow-up period was 32.9 months. Symptomatic relief was good. Lead dislodgment occurred in 11 patients (usually in the first week). Threshold rises not amenable to reprogramming occurred in three patients and loss of sensing occurred in seven patients but only one required intervention. Overall, 21 patients required reoperation. The type of lead did not influence the need for reoperation that appeared to be related to the experience of the operator. Complete atrioventricular block occurred in three patients, two of whom had carotid sinus hypersensitivity and one had sick sinus syndrome. Chronic atrial fibrillation occurred in five patients, none of whom required revision of the pacemaker system. Atrial pacing is a satisfactory pacing mode in patients with sick sinus syndrome. Provided satisfactory atrioventricular conduction has been shown by incremental atrial pacing to at least 120 beats/min and carotid hypersensitivity is absent, progression to complete atrioventricular block is uncommon. Greater implanting skills are required for good results.

Adult↗
PubMed1979

Incidence and significance of rising blood acetate levels during hemodialysis.

Recent work suggests that rising arterial acetate levels occur in some patients undergoing hemodialysis and that they may be responsible for some dialysis problems, particularly cardiovascular instability. Blood acetate levels and acetate flux rates have been determined in 20 adult and 4 pediatric patients during hemodialysis as well as in 4 patients with combined renal and hepatic failure. Rising acetate levels occurred in 25% of the adult patients, although they were stable in the children and the patients with renal and hepatic failure. The occurrence of hypotension during dialysis was unrelated to a high blood acetate level.

Acetates↗