sodium-pertechnetate-tc-99m and Heart-Defects--Congenital

Three main nuclear medicine methods are used in paediatric cardiology: sequential first-pass radionuclide imaging of the cardiac cavities, radionuclide equilibrium ventriculography and radionuclide myocardial imaging. Valuable functional information is obtained, and invasive explorations can be avoided in an ever increasing number of cases. Of particular interest is left-to-right shunt measurement which indicates that atrial septal defects must be surgically corrected when the pulmonary/systemic flows ratio (QP/QS) is above 2. This technique is also useful to evaluate the tightness of repairs in ventricular and atrial septal defects. Radionuclide studies of the right and left ventricles may detect dysfunction in one or the other cavity. The left ventricular ejection fraction is reduced in myocardiopathy an in aortic or mitral valve diseases seen at a late stage. The right ventricular function is often abnormal, notably during exercise, after repair of the tetralogy of Fallot and after atrial correction of complete transposition of the great arteries. An altered ejection fraction in patients with single ventricle is also a sign of deterioration. Right ventricular diastolic overload evaluated by radionuclide equilibrium ventriculography correlates with the QP/QS ratio value in atrial septal defects and with the inducibility of ventricular tachycardia by endocavitary pacing in repaired tetralogy of Fallot. Thallium 201 myocardial imaging provides information on myocardial ischaemia, notably that associated with congenital abnormalities of the coronary arteries. Its use had now been extended, albeit with some limitations, to the evaluation of right ventricular systolic overload. Other radionuclide techniques are being developed with new tracers: Kryton 81m for studies of the right ventricle, short-lived radionuclides for first-pass studies, Iodine 123-labelled fatty acids for myocardial imaging. More recently, some substrates, such as deoxyglucose, have been labelled with positron emitters permitting in vivo metabolic studies.

Topics: Cardiac Output; Child; Child, Preschool; Heart; Heart Defects, Congenital; Heart Diseases; Heart Ventricles; Humans; Infant; Infant, Newborn; Pulmonary Circulation; Radiation Dosage; Radioisotopes; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Thallium

Left ventricular (LV) ejection fraction (EF) was measured in 25 patients, aged 2 weeks to 20 years (mean 8.6 years), using a portable nonimaging scintillation stethoscope. Technically satisfactory studies were obtained in 23 patients. LVEF was validated by cineangiography in 19 patients and by standard gated blood pool scintigraphy in 4. EF measured by the nuclear stethoscope correlated well with values obtained by cineangiography or scintigraphy (r = 0.869, p less than 0.001) over a wide range of EF values (18 to 79%). In children younger than 5 years (n = 11), the correlation (r = 0.728, p less than 0.02) was less satisfactory than in those older than 5 years (r = 0.926; p less than 0.001). Although modifications in the instrument and further clinical trials with the stethoscope are needed before the device becomes clinically useful to pediatric cardiologists, our data indicate that the nuclear stethoscope can provide reliable assessment of LVEF in pediatric patients.

Topics: Adolescent; Adult; Cardiac Output; Child; Child, Preschool; Cineangiography; Computers; Heart Auscultation; Heart Defects, Congenital; Humans; Infant; Infant, Newborn; Microcomputers; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Stroke Volume; Technetium

With first-pass radionuclide angiography, it is possible to visualize sequentially the cardiovascular structures and to obtain computer-generated time-activity curves for regions of interest over these structures. Analysis of these curves permits the detection, localization, and quantitation of intracardiac shunts and shunts between the great arteries. The authors present the formulae used for the quantitative analysis and discuss clinical applications.

Topics: Ductus Arteriosus, Patent; Electrocardiography; Heart Defects, Congenital; Heart Septal Defects, Atrial; Heart Septal Defects, Ventricular; Hemodynamics; Humans; Infant; Infant, Newborn; Models, Cardiovascular; Postoperative Complications; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Tetralogy of Fallot; Transposition of Great Vessels

A 22 year old man with asymptomatic hypoxemia was found to have a large right to left shunt due to a rare congenital anomaly: total drainage of the right superior vena cava into the left atrium. The anomaly was first suspected after radionuclide angiocardiography was performed using technetium-99m macroaggregated albumin and was confirmed by cardiac catheterization. Contrast echocardiographic and surgical findings are discussed. Other reports on this anomaly are reviewed.

Topics: Adult; Cardiac Catheterization; Coronary Circulation; Echocardiography; Heart Atria; Heart Defects, Congenital; Humans; Hypoxia; Male; Serum Albumin; Sodium Pertechnetate Tc 99m; Technetium; Technetium Tc 99m Aggregated Albumin; Vena Cava, Superior

First pass radionuclide angiocardiography was utilized to calculate right and left ventricular ejection fraction in 74 infants and children. For the synchronization of radionuclide imaging with the cardiac cycle, the peaks and valleys of corrected ventricular time activity curve were adopted as the time reference points instead of R wave of electrocardiogram. Left ventricular ejection fractions obtained by the radionuclide technique correlated well with those derived from the contrast angiographic technique (r = 0.90), but right ventricular ejection fractions correlated less well (r = 0.74). This noninvasive technique appeared useful for evaluation of right and left ventricular ejection fraction.

Topics: Aortic Valve Insufficiency; Aortic Valve Stenosis; Cardiac Output; Cardiomyopathies; Child; Child, Preschool; Female; Heart Defects, Congenital; Heart Diseases; Humans; Infant; Male; Mitral Valve Insufficiency; Mucocutaneous Lymph Node Syndrome; Pulmonary Valve Insufficiency; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Stroke Volume; Syndrome; Technetium

Radionuclide angiocardiography was used to assess pulmonary vascular reactivity in eight patients (nine studies) with a large, relatively unrestrictive intracardiac defect and pulmonary arterial hypertension. Radionuclide angiocardiograms, using technetium-99m pertechnetate, were performed first with the patient breathing room air and then after 10 minutes of breathing a mixture containing 90 percent or more of oxygen. The pulmonary to systemic flow ratios obtained by gamma variate analysis of the radionuclide time-activity curves were compared with those calculated with the Fick principle at the time of cardiac catheterization. There was a good correlation between the two methods both in room air studies (r = 0.88) and in those obtained with 90 percent or more of oxygen (r = 0.94). All six studies (in five patients) with a reactive pulmonary vasculature (judged by a pulmonary vascular resistance at cardiac catheterization of less than 6 units/m2 with oxygen or after tolazoline) had a radionuclide pulmonary to systemic flow ratio of 3.0 or greater with oxygen. The three patients with a nonreactive pulmonary vasculature had a radionuclide pulmonary to systemic flow ratio of 2.3 or less with oxygen, a value that was unchanged from the room air value. These data suggest that radionuclide angiocardiography may be a useful, relatively noninvasive method of assessing pulmonary vascular reactivity in patients with a large, relatively unrestrictive intracardiac defect.

Topics: Angiocardiography; Cardiac Catheterization; Child, Preschool; Heart Defects, Congenital; Heart Septal Defects, Ventricular; Hemodynamics; Humans; Hypertension, Pulmonary; Infant; Pulmonary Artery; Pulmonary Circulation; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Technetium; Vascular Resistance

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.

Topics: Adolescent; Adult; Angiocardiography; Child; Child, Preschool; Coronary Circulation; Female; Heart; Heart Defects, Congenital; Heart Ventricles; Hemodynamics; Humans; Infant; Male; Sodium Pertechnetate Tc 99m; Technetium

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.

Topics: Cardiac Catheterization; Carotid Arteries; Child; Child, Preschool; Dye Dilution Technique; Female; Heart; Heart Defects, Congenital; Heart Rate; Humans; Infant; Male; Oximetry; Pulmonary Artery; Radioisotope Dilution Technique; Radionuclide Imaging; Sodium Pertechnetate Tc 99m; Technetium; Tetralogy of Fallot; Time Factors