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Biomedical subjects

R J Burns

Publications and source records attributed to R J Burns.

At least 19 recordsLinked to original sources
PubMed1992

Postoperative haemodynamic and pharmacological responses in patients with positive technetium pyrophosphate single-photon emission computed tomography following CABG.

The aim of this prospective study was to evaluate the postoperative haemodynamic variables and medication requirements in patients with perioperative myocardial infarction (PMI), following elective coronary artery bypass graft (CABG) surgery, as documented by technetium pyrophosphate scintigraphy using single-photon emission computed tomography (TcPPi-SPECT). A high-dose fentanyl anaesthetic technique was applied. Twelve of 58 patients (21%) developed PMI with an infarcted myocardial mass of 35.7 +/- 3.9 g. Over the 48 hr postoperative period, patients with positive TcPPi-SPECT (n = 12) did not differ from those with negative TcPPi-SPECT (n = 46) in mean heart rate (below 100 bpm), systolic blood pressure (100-120 mmHg) or central venous pressure (8-16 mmHg). However, patients with positive TcPPi-SPECT had higher pulmonary artery diastolic pressures at 5-8 hr after surgery. No differences were found in the incidence and dosage requirements for postoperative sedative or vasoactive drugs (morphine, diazepam, propranolol, lidocaine, nitroglycerin and nitroprusside) between the two groups. There was no difference in the incidence of dopamine requirement between the groups (positive-scan: 16.7%, negative-scan: 13.0%). However, the dopamine dosage for inotropic support was higher in the positive TcPPi-SPECT group over 24 hr (318.5 +/- 125.2 mg vs 71.2 +/- 24.7 mg, P less than 0.05) and 48 hr (869.1 +/- 19.0 mg vs 142.3 +/- 49.4 mg, P less than 0.001) periods after surgery. We postulate that careful control of postoperative haemodynamic variables did not prevent but may limit the extent of PMI in elective CABG patients.

Coronary Artery Bypass↗
PubMed1992

Reverse redistribution on exercise thallium scintigraphy: relationship to coronary patency and ventricular function after myocardial infarction.

OBJECTIVE: To define prevalence, pathophysiology and relation to thrombolytic therapy of reverse redistribution (appearance of a new, or worsening of an existing, scintigraphic defect on 4 h delayed images compared with the stress thallium image). DESIGN: Randomized, double-blind, placebo-controlled trial. SETTING: Referral centre. PATIENTS: Sixty-three patients with acute myocardial infarction. INTERVENTIONS: Tomographic exercise thallium scintigraphy, radionuclide angiography, and quantitative coronary angiography. MAIN RESULTS: Tomographic exercise thallium scintigraphy performed at day 10 revealed fixed defects in 15 patients, reversible defects in 22 patients and reverse redistribution in 26 patients; no difference in treatment assignment (tissue plasminogen activator versus placebo) was found among the three groups. Left ventricular function was similar in patients with fixed or reversible defects and reverse redistribution; global ejection fraction was 48 +/- 14, 51 +/- 10 and 48 +/- 5%, respectively, and regional infarct ejection fraction was 36 +/- 15, 40 +/- 13 and 37 +/- 18%, respectively. However, nitroglycerin administration resulted in a significantly greater improvement in regional ejection fraction in reverse redistribution patients (5 +/- 4%) than that in patients with fixed defect (2 +/- 5%, P < 0.05) or reversible defects (3 +/- 5%, P < 0.05). The infarct-related artery had a greater cross-sectional area in reverse redistribution patients (1.5 +/- 1.42 mm2) compared with those with reversible defects (0.50 +/- 0.26 mm2, P < 0.05), but was similar to fixed defect patients (1.04 +/- 0.88). CONCLUSIONS: Reverse redistribution on tomographic thallium scintigraphy is a frequent phenomenon (occurring in 40% of patients following acute myocardial infarction) and is independent of thrombolytic therapy. Patients with reverse redistribution have a more widely patent infarct-related artery and similar ventricular function, but significantly greater functional improvement following nitroglycerin administration compared with those with reversible or fixed defects. These data suggest myocardial salvage within the infarct zone in some patients with reverse redistribution.

Animals↗
PubMed1991

Improved specificity of myocardial thallium-201 single-photon emission computed tomography in patients with left bundle branch block by dipyridamole.

Reduced septal uptake of thallium-201 during exercise is frequently observed in patients with left bundle branch block (LBBB) and normal coronary arteries. This may reflect normal coronary autoregulation in response to lower septal oxygen demand; thus, dipyridamole, which uniformly exploits flow reserve, would be more accurate for diagnosis of coronary artery disease (CAD). Sixteen patients with LBBB underwent exercise and dipyridamole thallium-201 single-photon emission computed tomography and coronary angiography within 3 months. Sensitivity for detection of left anterior descending CAD (greater than 50% stenosis) was 0.83 for exercise and 1.00 for dipyridamole. Specificity was 0.30 (visual) or 0.20 (quantitative analysis) for exercise and 0.80 (visual) or 0.90 (quantitative) for dipyridamole (p less than 0.05). Dipyridamole combined with quantitative analysis also improved specificity of CAD detection overall (p less than 0.01). These data demonstrate that pharmacologic vasodilation is more accurate than exercise when diagnosing CAD by myocardial perfusion scintigraphy in patients with LBBB.

Aged↗
PubMed1991

South Australian carotid endarterectomy study.

OBJECTIVE: To determine the operative morbidity and mortality of carotid endarterectomy in South Australia. DESIGN: This was a prospective study on consecutive patients already selected independently by their treating clinicians for carotid endarterectomy. Patients were assessed before and after the operation by independent neurologists. SETTING AND PARTICIPANTS: The study involved all patients undergoing carotid endarterectomy in South Australia in public and private hospitals over the 20-months period of the study. All vascular surgeons agreed to participate. INTERVENTION: Two hundred and thirty-nine carotid endarterectomies were performed on 223 patients, always as primary procedures. MAIN OUTCOME MEASURES: Patient characteristics, angiographic findings and indications for surgery were documented before the operation by neurologists who then carried out postoperative assessments and determined neurological status at discharge. Follow-up at six and twelve months was by letter and telephone enquiry to general practitioners or direct to patients. RESULTS: The perioperative death and stroke rate was 6.3% including one stroke after angiography and before endarterectomy. Fourteen patients (5.9%) had strokes after the operation and three died as a result (1.3%). Three patients had reversible ischaemic neurological deficits. In 58 asymptomatic patients, operative morbidity was 3.4%. However, in 42 patients who had had a stroke before the operation, there were seven who had operative complications (16.7%). Neurological complication rates for individual surgeons varied from 0 to 13.8%. In the subsequent 12 months, follow-up of 214 patients revealed nine additional deaths (three known to be caused by stroke, four not caused by stroke and two of unknown cause) and six more cerebral infarctions (involving both operated and unoperated sides), an annual mortality plus stroke morbidity rate of 4.2%-5.1%. CONCLUSIONS: The morbidity and mortality of carotid endarterectomy in South Australia is acceptable by world standards but is high in the subgroup with a preceding stroke. In this audit, carotid endarterectomy had an average risk at least equal to one year of untreated carotid artery disease and did not diminish the expected stroke and death incidence after one year.

Adult↗
PubMed1991

Controlled release levodopa/carbidopa (Sinemet CR4) in Parkinson's disease--an open evaluation of efficacy and safety.

Twenty patients with moderately severe Parkinson's disease entered an open study of the efficacy and safety of a slow release preparation containing levodopa 200 mg and carbidopa 50 mg per tablet ('Sinemet CR4'). Following an initial four week baseline stabilisation period on conventional 'Sinemet' tablets, the patients were transferred to 'Sinemet CR4' and observed at intervals over the next 12 months. Fifteen patients completed the full year observation period. When compared with the baseline period, treatment with 'Sinemet CR4' was associated with longer periods of functional improvement and less fluctuation of response following each dose. The median (range) dose frequency was reduced from three (three-12) to two (two-seven) times daily (p less than 0.001) on 'Sinemet CR4' although median (range) total daily dose of levodopa was increased from 700 (375-2525) to 800 (400-2800) mg without any increase in adverse effects. Three patients developed peripheral neuropathy while receiving Sinemet CR4, but the association with this therapy is unclear. Overall 'Sinemet CR4' allowed a longer dosage interval and provided more stable control of disease manifestations than conventional 'Sinemet'.

Aged↗
PubMed1991

A clinical and pathological study of progressive supranuclear palsy.

The clinical features of 26 patients diagnosed as progressive supranuclear palsy are reviewed. The atypical findings were the relatively low frequency of visual complaints (23%) and of significant dementia (20%). As well, the characteristic eye signs, supranuclear ophthalmoplegia of vertical gaze, occurred some years after the onset of the initial symptoms in a small but substantial number (31%), which significantly delayed the diagnosis, in one case by as long as 18 years. The pathological studies on 2 of the clinical cases and an additional 6 cases showed the characteristic pattern of involvement of particular subcortical and brainstem nuclei. In particular, significant degeneration of the pedunculopontine tegmental nucleus was confirmed. Degeneration of the pedunculopontine tegmental nucleus may well play an important role in the motor disability in progressive supranuclear palsy.

Adult↗
PubMed1990

Effects of nifedipine versus hydralazine on sympathetic activity and cardiac function in patients with hypertension persisting on diuretic plus beta-blocker therapy.

In patients with hypertension persisting on combined diuretic and beta-blocker therapy, the effects of an additional 9-week therapy with a calcium antagonist (nifedipine) versus a classical arterial vasodilator (hydralazine) were compared for changes in blood pressure (BP), plasma catecholamines (n = 15), and left ventricular (LV) systolic and diastolic function (n = 6). Both drugs lowered BP, but nifedipine was significantly more effective in lowering systolic BP. Hydralazine increased both supine and standing plasma norepinephrine, nifedipine increased them only in the standing position and to a lesser extent. Patients on beta1-selective (n = 5) versus nonselective (n = 10) blockade showed similar responses. Left ventricular systolic function was not affected by hydralazine, whereas nifedipine increased the rate of ejection. In contrast, LV diastolic function was not affected by nifedipine, whereas hydralazine improved the peak filling rate. We conclude that arterial vasodilation by a calcium antagonist causes less sympathetic activation than caused by a classical arterial vasodilator. However, during short-term therapy in patients already on a diuretic and a beta blocker, nifedipine appears not to improve decreased LV diastolic function.

Adrenergic beta-Antagonists↗
PubMed1990

Covert orientation of visual attention in Parkinson's disease: an impairment in the maintenance of attention.

Covert orientation of attention was studied in a group of patients with idiopathic Parkinson's disease and compared to a matched control group using a cued reaction time task which measured disengagement, covert movement and engagement of attention. Parkinson patients had an increased response latency and disengaged from attended locations more readily than controls. This impairment in the maintenance of attention in Parkinson's disease was comparable to that produced in a previous study by pharmacological blockade of brain catecholamines in normal subjects. It is suggested that an impairment in the maintenance of oriented attention may underlie some of the cognitive deficits reported in Parkinson's disease.

Aged↗
PubMed1990

Creutzfeldt-Jakob disease in a recipient of human pituitary-derived gonadotrophin.

A forty-year-old female presented with an unsteady gait 13 years after receiving an eight-month course of human pituitary-derived gonadotrophin injections as treatment for infertility. Over the next ten months the patient subsequently developed generalised myoclonic jerks and dementia and finally died. Neuropathological examination revealed changes in the brain consistent with Creutzfeldt-Jakob disease. This is the first reported case of Creutzfeldt-Jakob disease in a recipient of human derived gonadotrophin.

Adult↗
PubMed1989

Myocardial infarction determined by technetium-99m pyrophosphate single-photon tomography complicating elective coronary artery bypass grafting for angina pectoris.

The incidence of acute myocardial infarction (AMI) complicating coronary artery bypass grafting (CABG) has previously been based on concordance of electrocardiographic, enzymatic and scintigraphic criteria. Technetium-99m pyrophosphate (Tc-PPi) single-photon emission computed tomography now enables detection of AMI with high sensitivity and specificity. Using this technique, perioperative AMI was detected in 12 of 58 patients (21%) undergoing successful elective CABG for stable angina pectoris. Stepwise multivariate logistic regression analysis was performed to compare the predictive value of preoperative (New York Heart Association class, left ventricular ejection fraction and use of beta blockers) and intraoperative (number of grafts constructed, use of internal mammary anastomoses, use of sequential saphenous vein grafts, smallest grafted distal vessel lumen caliber and aortic cross-clamp time) variables. Preoperative New York Association class (p = 0.04) and smallest grafted distal vessel lumen caliber (p = 0.03) were significant multivariate predictors of perioperative AMI. Only 1 perioperative patient with AMI (and 1 pyrophosphate-negative patient) developed new Q waves. Serum creatine kinase-MB was higher in patients with AMI by repeated measures analysis of variance (p = 0.0003). Five AMIs occurred in myocardial segments revascularized using sequential saphenous vein grafts, and 7 in segments perfused by significantly stenosed epicardial vessels with distal lumen diameter and perfusion territory considered too small to warrant CABG. At 6-month follow-up, the mean left ventricular ejection fraction increased from 0.61 to 0.65 in Tc-PPI-negative patients (p = 0.01), but not in perioperative patients with AMI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Mitral valve annuloplasty: the effect of the type on left ventricular function.

This study was undertaken to determine whether rigid-ring annuloplasty and flexible-ring annuloplasty have the same effect on left ventricular function in patients with chronic mitral regurgitation secondary to degenerative disease of the mitral valve. Twenty-five patients who underwent isolated mitral valve repair and required annuloplasty were randomized into two groups: rigid-ring and flexible-ring annuloplasty. Left ventricular function was assessed by echocardiography and radionuclide angiography on the day before operation and 2 to 3 months later. Preoperative left ventricular function was similar in the two groups of patients. Postoperatively, left ventricular end-diastolic diameter and volume decreased significantly in both groups. The left ventricular end-systolic diameter and volume decreased significantly only in patients with a flexible annuloplasty ring. Left ventricular systolic function as assessed by pressure-volume relationships was significantly better in patients with a flexible ring (p less than 0.02 by analysis of covariance), and left ventricular performance measured by stroke volume-end-diastolic volume relationships was also better in these patients (p less than 0.05 by analysis of covariance). These data indicate that patients with a flexible annuloplasty ring have better left ventricular systolic function than patients with a rigid annuloplasty ring 2 to 3 months after mitral valve reconstruction for chronic mitral regurgitation secondary to degenerative disease of the mitral valve.

Adult↗
PubMed1989

Postoperative myocardial infarction documented by technetium pyrophosphate scan using single-photon emission computed tomography: significance of intraoperative myocardial ischemia and hemodynamic control.

The aim of this prospective study was to document postoperative myocardial infarction (PMI) by technetium pyrophosphate scan using single-photon emission computed tomography (TcPPi-SPECT) in 28 patients undergoing elective coronary bypass grafting (CABG). The relationships of intraoperative electrocardiographic myocardial ischemia, hemodynamic responses, and pharmacological requirements to this incidence of PMI were correlated. Radionuclide cardioangiography and TcPPi-SPECT were performed 24 h preoperatively and 48 h postoperatively. A standard high-dose fentanyl anesthetic protocol was used. Twenty-five percent of elective CABG patients were complicated with PMI, as documented by TcPPi-SPECT with an infarcted mass of 38.0 +/- 5.5 g. No significant difference in demographic, preoperative right and left ventricular function, number of coronary vessels grafted, or aortic cross-clamp time was observed between the PMI and non-PMI groups. The distribution of patients using preoperative beta-adrenergic blocking drugs or calcium channel blocking drugs was found to have no correlation with the outcome of PMI. As well, no significant differences in hemodynamic changes or pharmacological requirements were observed in the PMI and non-PMI groups during prebypass or postbypass periods, indicating careful intraoperative control of hemodynamic indices did not prevent the outcome of PMI in these patients. However, the incidence of prebypass ischemia was 39.3% and significantly correlated with the outcome of positive TcPPi-SPECT, denoting a 3.9-fold increased risk of developing PMI. Prebypass ischemic changes in leads II and V5 were shown to correlate with increased CPK-MB release (P less than 0.05) and tends to occur more frequently with lateral myocardial infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗
PubMed1989

CNS cryptococcosis: unusual aspects.

Eleven patients with CNS cryptococcal infection are reviewed. The most prominent symptom was headache, present in all patients. The clinical manifestations were the direct result of the meningitis itself or a consequence of intracranial cryptococcal granulomata or hydrocephalus, these latter 2 complications being demonstrable on CT head scan. In the 2 patients who also had MRI scans, additional parenchymal lesions were revealed which had not been detected by CT. Combined amphotericin B and 5-fluorocytosine therapy was the treatment of choice, but in 3 patients fluconazole was also used. Chronic oral therapy with this agent has maintained a good clinical response in one patient who failed to respond to traditional antifungal therapy.

Adult↗
PubMed1988

Prenatal and adult presymptomatic testing for Huntington's disease.

The discovery of a fragment of DNA that is linked closely to the Huntington's-disease autosomal locus offers the opportunity for the presymptomatic diagnosis of this dominantly-inherited neurodegenerative disorder. Presymptomatic testing will present individuals and society with difficult choices and responsibilities. A pilot adult presymptomatic test programme is under way for SA families. Presymptomatic testing requires intensive counselling both before and after the test. A form of prenatal test, which is applicable to a significant proportion of couples with one partner at risk of Huntington's disease, is available also. As this form of prenatal test does not change the risk status of the parent, less extensive counselling is required and testing is available nationally through the SA programme. It is anticipated that other states will develop their own diagnostic programmes in the near future. This article explains the basis for the test, its accuracy and the importance of obtaining DNA from key individuals in pedigrees of Huntington's disease.

Female↗
PubMed1988

Calcium channel blockade does not offer adequate protection from perioperative myocardial ischemia.

This study aimed to detect the difference in hemodynamic and electrocardiographic responses during the prebypass period in patients undergoing coronary bypass grafting who were receiving beta-adrenergic blocking drugs, calcium entry blocking drugs, or both beta-adrenergic and calcium entry blocking drugs. Electrocardiographic evidence of myocardial ischemia was noted significantly more frequently in patients receiving calcium entry blocking drugs alone at induction of anesthesia (P less than 0.03), skin incision (P less than 0.05), and sternotomy (P less than 0.002). Heart rate at sternotomy was significantly higher in patients receiving calcium entry blocking drugs (P less than 0.02) as compared to patients receiving beta-adrenergic blocking drugs or the combination of both drugs. In conclusion, patients treated with calcium entry blocking drugs alone had significantly higher incidence of perioperative ischemic ECG changes compared with patients receiving beta-adrenergic blocking drugs alone or in combination with calcium channel blocking drugs.

Adrenergic beta-Antagonists↗
PubMed1986

Usefulness of radionuclide angiocardiography in predicting stenotic mitral orifice area.

Fifteen patients with pure mitral stenosis (MS) underwent high-temporal-resolution radionuclide angiocardiography for calculation of the ratio of peak left ventricular (LV) filling rate divided by mean LV filling rate (filling ratio). Whereas LV filling normally occurs in 3 phases, in MS it is more uniform. Thus, in 13 patients the filling ratio was below the normal range of 2.21 to 2.88 (p less than 0.001). In 11 patients in atrial fibrillation, filling ratio divided by mean cardiac cycle length and by LV ejection fraction provided good correlation (r = 0.85) with modified Gorlin formula derived mitral area and excellent correlation with echocardiographic mitral area (r = 0.95). Significant MS can be detected using radionuclide angiocardiography to calculate filling ratio. In the absence of the confounding influence of atrial systole calculation of 0.14 (filling ratio divided by cardiac cycle length divided by LV ejection fraction) + 0.40 cm2 enables accurate prediction of mitral area (+/- 4%). Our data support the contention that the modified Gorlin formula, based on steady-state hemodynamics, provides less certain estimates of mitral area for patients with MS and atrial fibrillation, in whom echocardiography and radionuclide angiocardiography may be more accurate.

Adult↗