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Biomedical subjects

M T Upton

Publications and source records attributed to M T Upton.

13 recordsLinked to original sources
PubMed1983

Treadmill exercise testing in hypertensive patients treated with hydrochlorothiazide and beta-blocking drugs.

Twelve patients with hypertension who did not become normotensive after treatment with hydrochlorothiazide alone were studied. Treadmill exercise testing was done before and after additional treatment to standing resting normotension with beta-blocker drugs. The double product (peak mean BP times peak heart rate) at peak performance fell significantly because of decreases in systolic arterial BP and heart rate, but diastolic pressures still rose with exercise in ten of the 12 patients, in seven of them to 100 mm Hg or higher. Thus, the data show that patients with hypertension treated to resting normotension with hydrochlorothiazide and a beta-blocker still often demonstrate a significant diastolic BP rise with exercise. In such patients, a rise in diastolic BP with exercise cannot be used as evidence of coronary atherosclerosis. The measurement of the arterial BP response to exercise is probably important in the assessment of the effectiveness of individual antihypertensive regimens.

Adrenergic beta-Antagonists↗
PubMed1982

Assessment of left ventricular function by resting and exercise radionuclide angiocardiography following acute myocardial infarction.

Left ventricular function was evaluated by first-pass radionuclide angiocardiography in 42 patients at 3 and 8 weeks following acute myocardial infarction. Left ventricular ejection fraction, diastolic volume, and wall motion were measured at rest and submaximal exercise at 3 weeks and at rest, submaximal and maximal exercise at 8 weeks. The mean ejection fraction, end-diastolic volume, and wall motion index did not change between 3 and 8 weeks in any group either at rest or during submaximal exercise. Ventricular function was decreased at rest in patients with previous and anterior myocardial infarctions, but not in patients with inferior and subendocardial myocardial infarctions. During maximal exercise at 8 weeks, nine patients (21%) had ST segment depression, whereas 25 patients (60%) had a decrease in ejection fraction or a deterioration in wall motion. These abnormalities of ventricular function during exercise occurred equally among the infarct groups. Radionuclide angiography in patients with recent myocardial infarction demonstrated highly variable ventricular function at rest and/or during exercise in each infarct subgroup.

Adult↗
PubMed1981

Accuracy of diagnosis of coronary artery disease by radionuclide management of left ventricular function during rest and exercise.

Rest and exercise radionuclide angiocardiographic measurements of left ventricular function were obtained in 496 patients who underwent cardiac catheterization for chest pain. Two hundred forty-eight of these patients also had an exercise treadmill test. An ejection fraction less than 50% was the abnormality of resting left ventricular function that provided the greatest diagnostic information. In patients with normal resting left ventricular function, exercise abnormalities that were optimal for diagnosis of coronary artery disease were an injection fraction at least 6% less than predicted, an increase greater than 20 ml in end-systolic volume and the appearance of an exercise-induced wall motion abnormality. The sensitivity and specificity of the test were lower in patients who were taking propranolol at the time of study and in patients who failed to achieve an adequate exercise end point. In the 387 patients with an optimal study, the test had a sensitivity of 90% and a specificity of 58%. Radionuclide angiocardiography was more sensitive and less specific than the exercise treadmill test. The high degree of sensitivity of the radionuclide test suggests that it is most appropriately applied to patient groups with a high prevalence of disease, including those considered for cardiac catheterization.

Adult↗
PubMed1980

Detecting abnormalities in left ventricular function during exercise before angina and ST-segment depression.

To determine if abnormalities in left ventricular function precede angina pectoris and electrocardiographic evidence of myocardial ischemia, we used radionuclide angiocardiography to measure left ventricular ejection fraction, volumes, cardiac output and wall motion in 10 normal subjects and 25 patients with coronary artery disease at rest and during two levels of upright bicylce exercise. In the patients with coronary artery disease, the first radionuclide study during exercise was performed before and the second after the onset of ST-segment depression. In all normal subjects, the ejection fraction increased more than 5%, the end-diastolic volume increased less than 25% and the end-systolic volume decreased from rest to both levels of exercise. Wall motion was normal at rest and increased with exercise. No patient with coronary artery disease had chest pain or ST-segment depression during the first level of exercise. The ejection fraction either decreased or increased less than 5% in 18 patients, the end-diastolic volume increased more than 25% in nine, the end-systolic volume increased in 19 and a segmental contraction abnormality developed in 14. Hemodynamic and wall motion abnormalities occurred in all patients during the second level of exercise when ST-segment depression was present. During exercise in patients with coronary artery disease, abnormalities in left ventricular function frequently develop before angina pectoris and electrocardiographic evidence of myocardial ischemia.

Adult↗
PubMed1979

Noninvasive assessment of hemodynamic effects of mitral valve commissurotomy during rest and exercise in patients with mitral stenosis.

Noninvasive radionuclide angiocardiography (RNA) provides simple and accurate assessment of parameters of cardiac function during rest and during maximal exercise. Left ventricular function was assessed by RNA in nine patients with isolated mitral stenosis before and approximately 6 months after mitral commissurotomy. Before operation, the mean mitral valve gradient was 14.0 +/- 2.8 mm Hg, and the mean mitral valve area was 1.20 +/- 0.3 cm2. Each patient was evaluated at rest and during maximal exercise on an isokinetic bicycle ergometer before and after commissurotomy. Heart rate, ejection fraction, end-diastolic volume, stroke volume, pulmonary transit time, cardiac output, and diastolic ventricular filling rate were determined by the radionuclide technique. Before operation, patients with mitral stenosis had characteristic changes from rest to exercise which supported restriction to diastolic ventricular filling as the primary limitation in generating a cardiac output during exercise. The stroke volume was unchanged from rest to exercise. Thus the cardiac output during exercise was heart rate dependent. However, after commissurotomy the stroke volume increased from rest to exercise. Therefore, cardiac output during exercise was achieved by heart rate and an augmented stroke volume. Moreover, the pulmonary transit time was reduced during rest and exercise after operation. The maximum ventricular ejection and filling rates were markedly increased during rest and exercise after commissurotomy. These differences in hemodynamic parameters at rest and during exercise document the mechanics of increased exercise tolerance in patients with mitral stenosis after mitral commissurotomy.

Adult↗
PubMed1977

Echocardiographic diagnosis of primitive ventricle with two atrioventricular valves.

Anatomical studies have shown that the pathognomonic feature of primitive ventricle is absence of that portion of the interventricular septum which interposes between the atrioventricular valves. The relation of this posterior septum to the atrioventricular valves is such that echocardiography should be a particularly suitable technique for showing its presence or absence. When a posterior septum is present, it is seen on an echocardiogram as a double echo between the two atrioventricular valves. It presence limits posterior movement of the septal cusp of the anterior atrioventricular valve. Absence of the posterior septum should, therefore, be seen echocardiographically as more than mere absence of the double septal echo. It should be possible to show unusual posterior excursion of the "septal" cusp of the anterior atrioventricular valve and apposition of the "septal" cusps of the atrioventricular valves during diastole. In most instances it should also be possible to demonstrate that the posterior great artery is in continuity with both atrioventricular valves. We have shown these echocardiographic features in 26 patients. The diagnosis of primitive ventricle has been confirmed at necropsy or at operation in 4 patients. In the other 22 patients in angiographic data are compatible with a diagnosis of primitive ventricle. Demonstration of these positive features at echocardiography is, therefore, of considerable value in the initial diagnosis of primitive ventricle and in particular its differentiation from other congenital malformations.

Echocardiography↗
PubMed1976

Instantaneous mitral valve leaflet velocity and its relation to left ventricular wall movement in normal subjects.

Echocardiograms showing mitral valve leaflets, interventricular septum, and posterior wall of the left ventricle simultaneously were recorded at a paper speed of 100 mm/s in 20 normal subjects. These records were manually digitized and a computer was used to derive mitral valve velocity, left ventricular dimension, and its rate of change continuously throughout a single cardiac cycle. The pattern of instantaneous mitral valve velocity with respect to time was similar in all subjects studied, showing a peak opening rate of 400 +/- 60 mm/s (mean +/- 1 SD), and continuously changing velocity throughout the period of mid-diastolic closure. The peak diastolic closure rate was 250 +/- 60 mm/s and thus appreciably higher than average velocities obtained by manually measuring the slope. A close time relation existed between mitral valve and left ventricular wall movement in early diastole. Forward movement of the anterior leaflet began 1 +/- 6 ms after the onset of outward wall movement, and peak velocity was reached 2 +/- 7 ms after the maximum rate of change of dimension. Later, a discontinuity in wall movement at the end of rapid filling preceded a corresponding discontinuity in the mitral valve velocity tracing by 5 +/- 10 ms. The technique, therefore, allows continuous measurement of mitral valve velocity, and demonstrates its close relation to left ventricular wall movement during diastole.

Adolescent↗
PubMed1976

Echocardiographic assessment of abnormal left ventricular relaxation in man.

In 64 patients requiring cardiac catheterization for chest pain, echocardiograms showing anterior mitral leaflet and left ventricular cavity simultaneously were recorded. These were digitized and their first derivatives computed in order to study time relations between mitral valve and left ventricular wall movement in early distole. In 10 patients with normal left ventricular angiograms and coronary arteriograms, mitral valve opening began 1-1 +/- 9-3 ms (mean +/- SD) before the onset of outward wall movement, and reached peak opening velocity 2-0 +/- 13 ms after maximum rate of change of dimension. Virtually identical time relations were seen in 15 patients with normal left ventricular angiograms but with obstructive coronary artery disease (3-6 +/- 9-3 ms and 0-7 +/- 7-3 ms, respectively). These close relations were lost in patients with segmental abnormalities of contraction on left ventricular angiogram. In 19 such patients with normal septal motion, outward wall movement began 53 +/- 31 ms before the onset of anterior movement of the mitral valve leaflet, and this isovolumic wall movement accounted for 31 per cent of the total diastolic excursion. In 9 patients with reversed septal movement, these abnormalities were greater, 92 +/- 39 ms and 33 per cent, respectively, while in 11 patients with diffuse left ventricular involvement they were small, 5-5 +/- 13 ms and 3 per cent. Frame-by-frame digitization of cineangiograms was used to confirm these findings which appear to reflect an abnormal change in left ventricular cavity shape during isovolumic relaxation.

Adult↗