PubMed Health⌕ Search

Biomedical subjects

C A Peter

Publications and source records attributed to C A Peter.

9 recordsLinked to original sources
PubMed1983

Radionuclide analysis of right and left ventricular response to exercise in patients with atrial and ventricular septal defects.

In patients with ventricular or atrial septal defect, the ventricle which is chronically volume overloaded might not appropriately respond to increased demand for an augmentation in output and thereby might limit total cardiac function. In this study we simultaneously measured right and left ventricular response to exercise in 10 normal individuals, 10 patients with ventricular septal defect (VSD), and 10 patients with atrial septal defect (ASD). The normal subjects increased both right and left ventricular ejection fraction, end-diastolic volume, and stroke volume to achieve a higher cardiac output during exercise. Patients with VSD failed to increase right ventricular ejection fraction, but increased right ventricular end-diastolic volume and stroke volume. Left ventricular end-diastolic volume did not increase in these patients but ejection fraction, stroke volume, and forward left ventricular output achieved during exercise were comparable to the response observed in healthy subjects. In the patients with ASD, no rest-to-exercise change occurred in either right ventricular ejection fraction, end-diastolic volume, or stroke volume. In addition, left ventricular end-diastolic volume failed to increase, and despite an increase in ejection fraction, left ventricular stroke volume remained unchanged from rest to exercise. Therefore, cardiac output was augmented only by the heart rate increase in these patients. Right ventricular function appeared to be the major determinant of total cardiac output during exercise in patients with cardiac septal defects and left-to-right shunt.

Adolescent↗
PubMed1982

Cardiac response to exercise in patients with chronic aortic regurgitation.

Rest and exercise measurements of left ventricular (LV) ejection fraction (EF) and volumes were obtained by radionuclide angiocardiography (RNV) in 30 patients with severe aortic regurgitation (AR). The ratio of peak systolic pressure to end-systolic volume was used as an index of contractility. Volumetric cardiac output (CO) averaged 11.7 +/- 3.8 L/min at rest and 18.4 +/- 5.6 L/min during exercise. Much individual variation occurred in LVEF and end-diastolic volume (EDV) responses to exercise, and there was no consistent change in these measurements. Resting hemodynamic parameters and clinical history correlated poorly with changes observed during exercise. An increase in heart rate was one mechanism used by all 30 patients to increase CO during exercise. An inverse relationship was defined between the change in myocardial contractility and the change in EDV during exercise. Patients with the greatest increase in contractility during exercise showed the greatest decrease in EDV. Less use of an exercise increase in contractility was associated with an exercise increase in EDV to meet the demand for greater CO. Therefore, exercise measurements of LV function provide unique information regarding the degree of impairment of the LV myocardium in these patients with chronic AR.

Adolescent↗
PubMed1981

Radionuclide angiocardiography in the diagnosis of congenital heart disorders.

Radionuclide angiocardiography provides a noninvasive assessment of cardiac function and blood flow through the heart and lungs. During the past three years, this procedure has been used at the Duke University Medical Center for evaluation of 343 patients with congenital heart disorders. A review of this experience shows tat the resulting data were frequently useful in the surgical management of these patients. In patients with abnormal blood flow patterns, noninvasive imaging of blood flow was useful before and after operative correction. Radionuclide measurements of left-to-right intracardiac shunts were sufficiently accurate for use in the initial evaluation of patients with murmurs and to document the absence of shunt after operative closure of intracardiac septal defects. Moreover, measurements of right-to-left cardiac shunts were of benefit in the management of children with cyanotic heart disease. Measurements of left ventricular function obtained during rest and exercise were most useful in patients with origin of the left coronary artery from the pulmonary artery and in patients with congenital valvular insufficiency. This experience demonstrates that radionuclide angiocardiography provides important measurements of central hemodynamics and cardiac function which are useful in the management of patients with congenital heart disorders.

Adolescent↗
PubMed1981

Radionuclide quantitation of right-to-left intracardiac shunts in children.

A simple, noninvasive method for measurement of right-to-left intracardiac shunts would enhance the management of patients with congenital heart disease. This study describes application of data processing techniques used previously in dye-indicator curves to data recorded during the initial transit of radioactive bolus through the central circulation. Radionuclide angiocardiograms were performed in 20 children, mean age 30 months, immediately after cardiac catheterization for congenital heart disease. The radionuclide data recorded over the carotid artery were used to replace arterial sampling required for dye indicators, and forward triangles were fitted to calculate the right-to-left shunt in an approach similar to that of Wood for indicator-dilution curves. Ten of the children had right-to-left shunts by Fick and radionuclide measurement, and 10 of the children with septal defects had no right-to-left shunt by either technique. Both the radionuclide and Fick measurements correlated well (r = 0.95). Therefore, radionuclide angiocardiographic data may be used for accurate calculation of right-to-left shunts in small children, eliminating the need for arterial sampling.

Cardiac Catheterization↗
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↗
PubMed1981

Effect of valve replacement for chronic mitral insufficiency on left ventricular function during rest and exercise.

In this study we measured left ventricular function at rest and during exercise before and after operation in 18 patients who underwent mitral valve replacement (MVR) for chronic mitral insufficiency. First-transit radionuclide angiocardiography was employed a week before operation and 5 to 19 months after operation to calculate left ventricular ejection fraction, volumes, output, filling, and emptying rates. Preoperatively, left ventricular ejection fraction increased from 0.56 +/- 0.09 (mean +/- S.D.) at rest to 0.62 +/- 0.11 during exercise, and this response was not altered for the group after operation. After valve replacement, there was no consistent change in end-diastolic volume (EDV), and cardiac function was not related to an alteration in filling rates of the left ventricle. After operation, the patient group achieved a maximal ventricular filling rate during exercise comparable to that measured before operation. In addition, postoperative maximal filling rates did not correlate with prosthetic valve size. These data suggest that the hemodynamic changes elicited by MVR for chronic insufficiency are primarily related to the elimination of the regurgitant flow but no attributable to alterations of the myocardium. It is suggested that limitation in exercise performance after operation may be primarily related to the functional status of the myocardium prior to operation.

Adult↗
PubMed1980

Radionuclide measurements of left ventricular function. Their use in patients with aortic insufficiency.

Radionuclide angiocardiography was used to measure left ventricular ejection fraction and end-diastolic volume while at rest and during exercise in 20 patients with severe aortic insufficiency. A second study was performed one year later in ten of these patients who did not undergo aortic valve replacement and in ten patients one year after operation. In patients without aortic valve replacement, the maximum ejection fraction achieved during exercise was 63% +/- 9% during the first study, and decreased to 57% +/- 9% after one year without a change in ejection fraction while at rest. No change in end-diastolic volume either while at rest or during exercise occurred during that period of time. In patients undergoing aortic valve reconstruction, the most striking change after one year was a decrease in end-diastolic volume from 296 +/- 107 to 148 +/- 37 mL at rest and from 306 +/- 92 to 155 +/- 38 mL during exercise. Ejection fraction increased by 10% at rest and 12% during exercise. Therefore, medically treated patients with aortic insufficiency lost the ability to increase ejection fraction during exercise without alteration of the ejection fraction while at rest over the one year of study. In contrast, aortic valve reconstruction resulted in a decrease in end-diastolic volume and an increase in ejection fraction during rest and exercise.

Adolescent↗
PubMed1980

Effects of isometric handgrip and dynamic exercise on left-ventricular function.

Radionuclide angiocardiography was used to assess cardiac function during isometric handgrip and bicycle exercise in ten normal volunteers and in 20 patients with documented coronary artery disease. Handgrip stress evoked a small increase in cardiac output that resulted from a concomitant increase in heart rate and no change in left-ventricular function. The most reliable criterion for diagnosis of coronary artery disease by handgrip was development of a new well-motion abnormality. However, abnormal wall motion was observed in only 45% of patients with coronary artery disease and in one of the ten normal subjects. In normal subjects, left ventricular function during bicycle exercise was characterized by an increase in left-ventricular ejection fraction with little change in cardiac volumes. The failure to increase left-ventricular ejection fraction by at least 0.05 identified 19 to 20 patients with coronary artery disease with no false positives. Therefore, bicycle exercise evokes a more dramatic cardiovascular response than handgrip stress and is the preferable stress modality for inducing abnormalities of left-ventricular function for detection of coronary artery disease.

Adult↗