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Biomedical subjects

K K Teo

Publications and source records attributed to K K Teo.

At least 109 records · Page 6Linked to original sources
PubMed1985

Use of impedance cardiography in evaluating the exercise response of patients with left ventricular dysfunction.

Invasive studies in patients with left ventricular dysfunction show that data at rest (e.g. ejection fraction-EF) are poor predictors of the changes in cardiac output (CO) which occur with exercise. This investigation was undertaken to determine whether impedance cardiography could be used in such patients to assess CO response to exercise. The method was compared with the direct Fick method. Over a range of COs between 4 and 18 min-1 there was no systematic error. Reproducibility for CO over one week was highly significant (r = 0.94; P less than 0.001). Impedance cardiography was incorporated into routine exercise testing on a bicycle ergometer for a group of 15 patients (mean age 53.2 +/- 3.0 yrs, SEM) who had sustained a major myocardial infarct 6 to 12 months previously, (EF 38.1 +/- 3.5%, SEM). CO was measured at the end of each 3-min stage. In eight patients (EF 40.0 +/- 3.4%, SEM) CO response was abnormal with either a decrease or a failure to increase with increasing workloads. Conventional end-points i.e. angina, attainment of 85% of predicted maximum heart rate, abnormal blood pressure response or excessive dyspnoea did not indicate consistently a need to terminate the test. It is suggested that impedance cardiography is a useful non-invasive method of evaluating patients with left ventricular dysfunction.

Adult↗
PubMed1985

Interaction of left atrial receptors and carotid sinus baroreceptors on heart rate in the dog.

This study was undertaken to determine the influence of 1) the left atrial receptors (LA) on the ability of the carotid sinus baroreceptors (CS) to regulate heart rate and 2) the CS on the reflex increase in heart rate mediated by the LA. The LA were stimulated by stretching the pulmonary vein-atrial junctions in dogs anesthetized with alpha-chloralose. Aortic pressure was controlled, and the pressure in the CS was regulated. Stimulus-response curves were obtained relating heart rate to pressures in the CS, in the control state, and during stimulation of LA (6 dogs). Factorial analysis revealed that LA exerted a significant influence on heart rate (P less than 0.01). Next the CS pressure was set at mid, low, and high levels and the LA stimulated. It was found that the effect on heart rate was greatest at the mid setting (+19.3 +/- 2.9 beats/min) and least at the low setting of the pressure in the CS (+0.9 +/- 0.5, 11 dogs). Sympathetic blockade attenuated significantly the response in the mid setting of the CS pressure and left intact the response at the high setting of the pressure in the CS. It is concluded that there is a significant interaction between these two reflexes.

Animals↗
PubMed1985

Sotalol infusion in the treatment of supraventricular tachyarrhythmias.

Sotalol, a noncardioselective beta-adrenergic blocking agent without partial agonist activity, has class-3 antiarrhythmic effects. Twenty-nine patients with supraventricular tachyarrhythmias were treated on 31 occasions to determine the effective therapeutic dosage and optimal method of administration. Fifty percent of patients with paroxysmal supraventricular tachycardia, 33 percent of those with atrial flutter, and 20 percent with atrial fibrillation were restored to sinus rhythm by bolus administration; and when sotalol was given by continuous infusion, sinus rhythm was obtained in 100 percent, 86 percent, and 33 percent, respectively. Comparable dosages were given to both responders and nonresponders in the bolus-treated group and higher dosages to nonresponders than to responders in those treated by infusion. Furthermore, plasma levels in nonresponders tended to be higher than in responders. When responders alone were considered, the average dose required was 0.630 +/- 0.090 mg/kg of body weight (+/- SE), and the plasma level obtained was 0.526 +/- 0.088 microgram/ml. No relationship between plasma levels and therapeutic effectiveness was shown. No serious side effects were observed at the dosages used. These data suggest that while no concordance with plasma levels was observed, sotalol given by infusion is an effective therapy for atrial flutter and supra-ventricular tachycardia. It is less effective in atrial fibrillation, where less than half were responders, but a satisfactory reduction in ventricular rate response was obtained. A controlled trial to further substantiate these findings is indicated.

Adult↗
PubMed1984

Comparative response of male and female patients with coronary artery disease to exercise rehabilitation.

Male (227) and female (37) participants in a supervised rehabilitation programme for patients with coronary artery disease were compared in relation to their compliance with and response to the programme. The drop-out rate was higher in females (18.9% vs 7.9%) and their attendance rate at sessions was lower (77% vs 87%). Following the programme, exercise duration was significantly increased in both groups to a similar degree, although absolute values were consistently higher in males. The heart rates required to perform given workloads were reduced for both sexes, the magnitude of reduction being similar. Blood pressure was not altered after rehabilitation. These findings show that female patients, despite poorer compliance than males, can benefit equally from exercise rehabilitation.

Blood Pressure↗
PubMed1983

Perhexiline during exercise training in coronary heart disease.

The effects of low-dose perhexiline on the exercise training response of 22 male patients, 14 after myocardial infarction and 8 after coronary artery bypass who underwent exercise training, were examined. All subjects underwent treadmill exercise testing and resting left ventricular function evaluation by radionuclide ventriculography before and after an 8-wk course of three-times-weekly exercise training. Blood levels of perhexiline confirmed that there was a steady state sufficient for antianginal therapy. There were no side effects. There were improvements in exercise tolerance in treated and placebo groups. There were no significant intergroup differences. Resting left ventricular ejection fraction and end-systolic and diastolic dimensions were not altered. Resting blood pressures were not affected by treatment. There was no evidence of a beta-adrenoceptor-blocking effect. Perhexiline during exercise training did not impair the training response.

Coronary Disease↗
PubMed1982

Abnormal cardiac enzyme responses after strenuous exercise: alternative diagnostic aids.

Serial estimations of activities of creatine kinase and its MB isoenzyme, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase and of concentrations of alpha(1)-acid glycoprotein were performed in 15 healthy well-trained male marathon runners. Estimations were made initially within three days before a race and then one, 24, and 96 hours after the race. Technetium-99m pyrophosphate myocardial scintigraphy was carried out at the initial prerace assessment and repeated 48 to 96 hours after the race. None of the subjects developed cardiac symptoms during or after the race.Activities of creatine kinase and creatine kinase MB became maximal 24 hours after the race. One and 96 hours after the race two and five subjects, respectively, showed amounts of creatine kinase MB totalling 5% or more of total creatine kinase. Lactate dehydrogenase activity peaked at one hour after the race, and activities of aspartate and alanine aminotransferases peaked at 24 and 96 hours after the race, respectively. Activities of all these enzymes showed a significant increase from prerace values during the rest of the study. Electrocardiographic features noted were similar to those reported elsewhere in athletes under similar conditions. They included first-degree heart block, incomplete right bundle-branch block, left ventricular hypertrophy, pseudoischaemic T-wave changes, and early repolarisation of variant ST-segment elevations in precordial leads. Technetium-99m pyrophosphate myocardial scintigraphy did not show evidence of myocardial damage before or after the race. Alpha(1)-acid glycoprotein concentrations were normal throughout.These data suggest that reliance on standard enzyme estimations and electrocardiographic criteria may yield false-positive indicators of myocardial injury during prolonged strenuous exercise. Technetium-99m pyrophosphate scintigraphy and alpha(1)-acid glycoprotein measurements offer additional information and may usefully be employed in evaluating circulatory collapse associated with such exercise.

Adult↗
PubMed1981

Echocardiographic evaluation of left ventricular function in patients showing an antihypertensive and biochemical response to indapamide.

Left ventricular function was evaluated non-invasively in hypertensive patients treated with indapamide by means of echographically determined velocity of circumferential fibre shortening (VCF). A statistically significant reduction in mean systolic and diastolic blood pressure in both the standing and supine position (P less than 0.001) and after exercise, systolic (P less than 0.001) diastolic (P less than 0.05) occurred but no alteration in left ventricular function was found. Blood lipids showed no change from pre-treatment levels. Serum uric acid demonstrated a significant elevation and serum potassium a significant fall but each remained within the normal range. Three patients required potassium supplementation. A significant rise in serum sodium and fall in serum chloride, both remaining within the normal range, occurred.

Adult↗
PubMed1980

The effects of topical and oral slow-release nitroglycerin on anterior myocardial infarction size assessed by precordial ST segment mapping.

The effect of slow-release nitroglycerin and nitroglycerin ointment in reducing anterior myocardial infarction size was assessed in 18 patients by means of epicardial mapping. The sum of all ST elevations (sigma ST), the number of leads with ST elevations greater than 1 mm (NST), the sum of the ST segment elevations of those leads with ST elevations greater than 1 mm (sigma STmm) and the average ST segment elevations (ST) were evaluated. No statistically significant difference between the two forms of nitroglycerin and placebo was found over a 72-h period. These data suggest that no benefit in terms of reduction in myocardial infarction size, assessed by epicardial mapping, is obtained from therapy with oral slow release nitroglycerin and nitroglycerin ointment.

Administration, Oral↗
PubMedDate not supplied

Cardiac rehabilitation referral and attendance: not one and the same.

Despite empirical evidence that cardiac rehabilitation programs can play a significant role in enhancing recovery following a primary cardiac event and in enacting secondary prevention measures, attendance rates remain remarkably low. Referral and attendance at cardiac rehabilitation programs are not one and the same. Recognizing this, issues related to the referral of eligible patients to cardiac rehabilitation and factors that affect patients' decisions regarding attendance must be identified and addressed. This article presents an overview of the potential benefits of cardiac rehabilitation programs, describes salient issues related to referral and attendance, and identifies directions for future research.

Coronary Disease↗