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Biomedical subjects

W E Adam

Publications and source records attributed to W E Adam.

At least 73 records · Page 4Linked to original sources
PubMed1981

Evaluation of aortic and mitral valve regurgitation by radionuclide ventriculography: comparison with the method of Sandler and Dodge.

The present investigation was undertaken to introduce a quantitative scintigraphic method for evaluation of regurgitation and to compare it with the generally accepted quantitative method of Sandler and Dodge (Sandler et al., 1963). Radionuclide ventriculography was carried out after injection of 20 mCi 99mtechnetium-labeled red blood cells. Time-activity curves were obtained from the left and right ventricular regions. The ratio (A) of end-diastolic-end-systolic count-rate differences for the left and right ventricles was calculated. The ratio (A) was compared with a hemodynamic ratio (Ah) determined after the method of Sandler and Dodge (1963) with the stroke volume of the left ventricle measured angiographically, and the stroke volume of the right ventricle measured by thermodilution. In 33 patients with aortic and mitral valve regurgitation we found a correlation of r = 0.75 between (A) and Ah). Due to a broad range of normal values of (A) the sensitivity of the scintigraphic method is low. The specificity seems to be high, however, since in 64 patients with all types of heart diseases there were no false positive results. Comparing the described scintigraphic method with other modern or generally accepted methods, the principal advantages are noninvasiveness, good practicability, and the fact that important additional information about the functional state of the heart is gained. This is important in follow-up studies in patients with chronic valvular incompetence. It seems that this method will become a valuable supplement to heart catheterization in the diagnosis of valvular heart disease and may partially replace invasive methods for measuring the regurgitation fraction.

Adult↗
PubMed1981

[Determination of endogenous labelling of thyroid hormones during a radioiodide test in euthyroid goiter patients and hyperthyroid patients (author's transl)].

The administration of a diagnostic dose of radioiodide, as in the radioiodide uptake test, results in the formation and secretion of radioactive thyroid hormones (endogenous labelling). In this report a method is described by which thyroid hormones are chromatographically isolated from serum, with the simultaneous assessment of the incorporated radioactivity over a period of time. A low-level counter was used to measure the small amounts of activity present. By this method the hormone phases during a radioiodide uptake test may be better evaluated. The present results show a good diagnostic discrimination between euthyroidism and borderline or definite hyperthyroidism (by a factor of 10 and 40, respectively). The influence of factors such as a small intrathyroidal iodide pool need, or course, to be considered. Hence, by taking into account such parameters as the intrathyroidal iodide pool, the hormone clearance etc, a technique for the measurement of thyroid hormone secretion can be developed.

Goiter↗
PubMed1981

[Assessment of left ventricular regional function by means of radioactive isotopes (author's transl)].

Extensive analysis of heart function by scintigraphy yields global parameters of ventricular volumes and their changes during the heart cycle (ejection fraction, enddiastolic and endsystolic volumes, velocity of contraction and relaxation). Additionally, information regarding localized disorders of wall motion may be obtained in a qualitative and quantitative manner by the parameters "phase" and "amplitude". These parameters can be computed from regional time-activity curves by Fourier analysis. The radionuclide ventriculogram at rest is suitable for the detection and follow-up of asynergies caused by acute and chronic infarction. In can also be used as a method of distinguishing between reversible and irreversible asynergy by therapeutical intervention (intervention ventriculography). Abnormalities of regional wall motion which develop during exercise may indicate hemodynamically relevant coronary artery stenoses.

Cardiac Output↗
PubMed1980

Assessment of the left ventricular function with the nuclear stethoscope.

The evaluation of the left ventricular function with the "Nuclear Stethoscope" was performed on 27 patients with heart diseases. The reproducibility of the measurements was good. Repetitions of EF, ER and EDV estimations yielded errors of 2.63%, 1.45% and 0.31%, respectively. The comparison with the results of camera ventriculography showed a good agreement of EF, contraction velocity parameters and relaxation velocity parameters, with a cor. coeff. of greater or equal to 0.750. An especially high correlaton was found between the NS EF and NS ER (r = 0.968). It was concluded that the "Nuclear Stethoscope" provides a reliable evaluation of left ventricular function.

Adult↗
PubMed1980

[Radionuclide ventriculography as a special case of functional scintigraphy (author's transl)].

Computer processed dynamic scintigraphy (CPDS) (Funktionsszintigraphie), as developed 15 years ago essentially in the German Cancer Research Center (Institute of Nuclear Medicine), Heidelberg, shows limitations with regard to temporal spatial resolution. Under fixed count rate conditions, temporal resolution can only be improved at the expense of spatial resolution. The adverse implications of this inverse relationship may be overcome by the use of trigger techniques, resulting in an improvement in statistical information. The strict application of principles as developed in CPDS in gated blood pool procedures leads to parametric scans (functional imaging) displaying optimal utilisation of available information and presentation of regional wall motion abnormalities.

Evaluation Studies as Topic↗
PubMed1979

Predictive value of radionuclide methods in the diagnosis of unilateral renovascular hypertension.

The validity of noninvasive (iodine-131 iodohippurate renogram, iodine-131 ortho-iodohippurate clearance, indium-113m EDTA--technetium-99m DTPA sequential renal scan) and invasive (xenon-133 washout) radionuclide screening tests was evaluated in the diagnosis of 105 patients with unilateral renovascular hypertension (RVH) and in 45 patients with essential hypertension (EH). In RVH positive findings on the stenosed side were noted in 73% of renograms, 73% of o-iodohippurate-clearance tests (N = 22), 81% of sequential renal scans, and 90% of xenon-washout studies (N = 67). In a subgroup of 55 retrospectively selected patients with normal or improved blood pressure following renovascular surgery, the preoperative findings had been positive on the stenosed side in 78% of renograms, 75% of o-iodohippurate-clearance tests (n = 20), 85% of sequential renal scans, and 93% of xenon-washout studies (n = 23). The sequential renal scan appears to be a sufficiently reliable method in noninvasive screening for unilateral RVH, although invasive xenon-washout studies show a higher percentage of hemodynamic alterations in the stenosed kidney. o-iodohippurate clearance tests, and in particular xenon-washout studies, can reveal arteriosclerotic lesions in the contralateral, non-stenosed kidney, which may be of importance when the decision for renovascular surgery is pending.

Female↗
PubMed1978

Effects of saralasin on blood pressure, renin and renal blood flow in unilateral renovascular hypertension.

The effect of saralasin, a competitive inhibitor of angiotensin II, was assessed in hypertensive patients with unilateral renal artery stenosis after furosemide application. A significant fall of systemic arterial blood pressure, an increase of renal venous renin activity, significantly on the stenosed side in patients without arteriosclerosis of the contralateral kidney, and an almost equal decrement of renal blood flow in both kidneys were observed. Conceivably saralasin exerts different sodium-dependent effects on peripheral angiotensin II and specific intrarenal vascular receptors.

Angiotensin II↗
PubMed1978

[Radionuclide ventriculography. I. Fundamentals and methods (author's transl)].

Using local time activity curves parameters are calculated which depend on the local wall motion of the heart cavities. These functional parameters allow the determination of the contours of the heart cavities and the assessment of segmental wall motion disorders. The left ventricular ejection fraction has been calculated by enddiastolic and endsystolic counts using a method which takes into account background inhomogeneity.

Electrocardiography↗
PubMed1978

[Radionuclide ventriculography. II. Clinical results--parameters of global ventricular function (author's transl)].

The ejection fraction as determined by gated blood pool studies was compared with the ejection fraction as evaluated by the following conventional methods: 1) biplane cineangiography employing the Simpson rule. Correlation was r = 0.805 (n = 25); 2) the same patients using the area-length method (r = 0.88, n = 25); 3) monoplane cineangiography using the method of Greene et al. (5) (r = 0.86, n = 35). In 20 patients the maximal contraction velocity as evaluated by radionuclide ventriculography was compared with the mean systolic ejection rate. The observed correlation was weak (r = 0.62, n = 20); however, it should be noted that the radionuclide method determines the maximum contraction velocity whereas cinceangiography measures an average value over the whole systole.

Cineangiography↗
PubMed1978

[Radionuclide ventriculography. III. Clinical results--parameters of regional wall motility (author's transl)].

Radionuclide ventriculography and cineangiography were performed in 62 patients with suspected coronary artery disease. Regional wall motility irregularities could be demonstrated in 97% of those patients who revealed an irregularity in the cineangiogram. Two small scars of the posterior myocardial wall escaped detection. The sensitivity of the radionuclide ventriculography was 97%, the specificity was 80%, 4 patients with normal cineangiography showed small irregularities in the radionuclide ventriculogram. 70 patients with infarction revealed wall motility irregularities in 90%, whereas perfusion defects could be detected by thallium scintigraphy in 66% (young and old infarctions).

Cineangiography↗
PubMed1977

[Regional myocardial motility as evaluated by analysis of "gated blood pool" data (author's transl)].

Cyclic precordial variations of radiation after i.v. administration of 15 mCi 99mTc-HSA correspond to cyclic volume changes of ventricular volumes of the heart. The "gated blood pool procedure" yields reliable data. Extensive analysis of these data results in subsequent information concerning left ventricular myocardial behaviour: 1. extent of the regional myocardial contraction 2. homogeneity of the contraction 3. regional contraction velocity 4. regional relaxation velocity. Four parametric scans present the distribution of each one of those parameters within the heart. Gated blood pool data have been compared with angiographic data. Reliability of those parameters obtained by extensive analysis of the gated blood pool data could be proven.

Adult↗