Biomedical subjects

T Kappagoda

Publications and source records attributed to T Kappagoda.

24 records · Page 2Linked to original sources

PubMed1985

Incremental value of the exercise treadmill test in determining the extent of coronary artery disease: a discriminant function analysis.

This study was undertaken to determine whether it was possible to use a multivariate discriminant function analysis to assess the severity of coronary artery disease in patients with angina pectoris. One hundred and forty-three patients diagnosed as having angina pectoris who formed a 'learning group' were subjected to an exercise test on a treadmill using a Bruce protocol. The items of data from the test least likely to be influenced by beta blockade were considered for the analysis along with two discrete variables (the gender and the use of beta blockers). All the patients subsequently underwent coronary angiography and the severity of the coronary artery disease was graded according to a scoring system. In addition, patients in 'learning group' were classified into two 'Groups', (I) those with normal vessels or with disease in one or two of the major arteries, (II) those with disease in the left main stem or in all three major arteries. The multivariate analysis yielded a score based upon 4 factors: (i) gender, (ii) percentage increase in double product at the highest level of exercise achieved, (iii) duration of ST depression in the recovery period and (iv) the summation of the ST depression in the standard electrocardiogram excluding lead aVR. There was a significant overall correlation between the discriminant function score and the coronary artery score for severity of the disease. In addition, it was found that, of patients having discriminant function score below 0, 96% (69/72) were in Group I. The post-test risk of a positive test was 0.005.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

PubMed1985

Localization of coronary artery disease with exercise induced ST segment depression: coronary angiographic correlation.

Abnormalities of the 12 lead electrocardiogram (ECG) are often used to localize the anatomic site of myocardial ischemia and vessel involvement in patients (pts) with coronary artery disease. This study is to determine if ischemia of specific vascular segments can be identified by exercise induced ST segment depression (STD) on 12-lead ECG. One hundred and forty three pts with a positive treadmill stress testing (TST) who had coronary arteriography within one month of TST were reviewed. There were 114 men and 29 women, aged 34-74 years (mean 55 years). The Bruce protocol was used for TST. Significant coronary stenosis was defined as obstruction of 70% or greater of the luminal diameter. The pattern of STD on 12 lead ECG during exercise was similar in pts with single vessel disease involving the left anterior descending artery (LAD), right coronary artery (RCA) or circumflex artery (Cx). This pattern of STD in single vessel disease was also comparable to 2-vessel, 3-vessel or left main stem disease. Twenty-two percent of pts with LAD disease had isolated STD in inferior leads. Twenty-five and 29% of pts with RCA and Cx disease respectively had STD in the anterior leads alone during exercise testing. It is concluded that exercise induced STD in 12 lead ECG can not predict ischemia of specific vascular segments or specific vessel involvement.

Adult↗

PubMed1984

Evidence for cardiovascular autonomic nerve dysfunction in multiple sclerosis.

In 21 patients with multiple sclerosis and 20 healthy controls, the following tests of autonomic function were examined: (1) variation in heart rate during deep breathing, (2) the variations in heart rate and systolic blood pressure during a standardised Valsalva manoeuvre, (3) the changes in heart rate and systolic blood pressure during arm ergometry starting at 30 W with increments of 20 W every 3 min. In the control subjects the maximum variation in heart rate from inspiration to expiration was greater than 16 beat/min (range 17-43). In patients with multiple sclerosis, five had a maximum variation in heart rate of less than 13 beat/min which was considered as the lower limit of normal. The Valsalva ratio in the control subjects ranged from 1.33-3.24. Four patients had Valsalva ratios of less than 1.30. In patients with multiple sclerosis the heart rate and systolic blood pressure responses to exercise were attenuated significantly in four and seven subjects respectively. It is concluded that a significant number of patients with multiple sclerosis show evidence of autonomic dysfunction involving the cardiovascular system.

Adult↗

PubMed1984

Tetrodotoxin-resistant relaxation to transmural nerve stimulation in isolated saphenous vein.

The response to transmural nerve stimulation (TNS) was characterized in rings of canine saphenous veins following sympathetic (guanethidine 10(-4) mol/l; phenoxybenzamine 2 X 10(-5) mol/l; propranolol 2 X 10(-6) mol/l) and muscarinic blockade (atropine 5 X 10(-6) mol/l). In preparations which were contracted with prostaglandin F2 alpha, TNS was applied as intermittent trains of stimuli of 30 s duration at frequencies of 1-32 Hz. This stimulus elicited a frequency-dependent relaxation [maximum relaxation 3.4 +/- 0.21 (SE) g]. This relaxation was present in rings denuded of endothelium and was not altered significantly by cimetidine (10(-4) mol/l), indomethacin (10(-5) mol/l), aminophylline (10(-5) mol/l), or cyproheptadine (10(-6) mol/l). It was abolished by the Na+-K+-ATPase inhibitor ouabain (2 X 10(-4) mol/l) and in zero-K+ Krebs solution. When the experiment was repeated following storage of the isolated saphenous veins for 9 days at 4 degrees C TNS failed to induce any relaxation. However, the relaxation in fresh rings was not abolished by tetrodotoxin (10(-6) mol/l). The present study demonstrates a nonadrenergic noncholinergic relaxation to TNS in the saphenous vein which could be mediated by 1) a tetrodotoxin-resistant nerve or 2) a direct effect of TNS on the smooth muscle.

Aminophylline↗

PubMed1981

An accurate method for the continuous measurement of oxygen consumption in infants during cardiac catheterization.

This paper describes the assessment of a method for measuring the oxygen consumption of infants and young children that is suitable for use in the cardiac catheterization laboratory. It is based upon the open-circuit technique and permits the continuous display of the oxygen consumption during the investigative procedures. The accuracy of the apparatus was assessed over the range 40-200 ml/min, both in vitro and in vivo. It was found that the apparatus was free from systematic error and that it had a random error of approximately 2% of the measured value.

Cardiac Catheterization↗

PubMedDate not supplied

The value of sum of ST segment depression in 12-lead electrocardiogram in relation to change in heart rate during exercise to predict the extent of coronary artery disease.

The present study was planned to investigate whether the sum of ST segment depression in 12-lead electrocardiogram (sigma STD) in relation to change in heart rate (delta HR) during exercise, sigma STD/delta HR index, could be utilized to predict the extent of underlying coronary artery disease. Two hundred and twenty-six consecutive patients were included in this study, 191 men and 35 women, aged 28-74 years (mean 56). Patients were classified into two groups. Group I consisted of 165 patients with either no coronary disease, single or double vessel disease. Group II included 61 patients with triple vessel or left main stem stenosis. It was found that the sigma STD/delta HR index at 25 mm. beat-1 X min. 10(2) provided the best separation between Groups I and II patients. All but 3 of the 61 patients in Group II had a sigma STD/delta HR index greater than 25. In contrast, all but 4 of the 165 patients in Group I had an index less than 25. The sensitivity, specificity and positive predictive value in the identification of Group II patients by using the index were 95%, 98% and 94% respectively. Utilization of ST segment depression of greater than or equal to 2 mm in a VF alone as a test criterion for the recognition of Group II patients had a low sensitivity (41%), specificity (88%) and positive predictive value (56%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗