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Biomedical subjects

H R Schelbert

Publications and source records attributed to H R Schelbert.

At least 217 records · Page 12Linked to original sources
PubMed1975

Nontraumatic determination of left ventricular ejection fraction by radionuclide angiocardiography.

Previous reports have suggested that left ventricular ejection fraction can be assessed by recording the passage of peripherally administered radioactive bolus through the heart. The accuracy and validity of this technique were examined in 20 patients undergoing diagnostic cardiac catheterization. 99m-Tc-human serum albumin was injected via a central venous catheter into the superior vena cava and precordial activity recorded with a gamma scintillation camera interfaced to a small digital computer. A computer program was designed to generate time-activity curves from the left ventricular blood pool and to calculate left ventricular ejection fractions from the cyclic fluctuations of the left ventricular time-activity curve which correspond to left ventricular volume changes during each cardiac cycle. The results correlated well with those obtained by biplane cineangiocardiography (r equals 0.94) and indicated that the technique should allow accurate and reproducible determination of left ventricular ejection fraction. The findings, however, demonstrated that the time-activity curve must be generated from a region-of-interest which fits the left ventricular blood pool precisely and must be corrected for contributions arising from noncardiac background structures. This nontraumatic and potentially noninvasive technique appears particularly useful for serial evaluation of the acutely ill patient and for follow-up studies in nonhospitalized patients.

Adult↗
PubMedDate not supplied

Doxorubicin cardiotoxicity: response of left ventricular ejection fraction to exercise and incidence of regional wall motion abnormalities.

Gated radionuclide ventriculograms were performed to evaluate cardiac function in 53 patients who received doxorubicin treatment for various malignancies (mean dose: 449 +/- 128 mg/m2 BSA). In fourteen patients (Group I) function was evaluated before and after treatment; there was a significant decrease of resting left ventricular ejection fraction after therapy (p less than 0.001). Twenty-two patients (Group II) had serial studies during treatment which also showed a significant fall of resting left ventricular ejection fraction (p less than 0.001). Eighteen patients in Groups I and II had supine exercise studies. A normal exercise response was maintained in the majority of patients. Exercise testing added little to the diagnostic performance when compared to serial resting studies. We found regional wall motion abnormalities (mild apical hypokinesis) at rest by visual inspection in 33 of 36 Group I and Group II patients who had received doxorubicin. In the baseline or initial study, only 4 of these patients demonstrated WMA. In 18 Group I and II patients who were exercised, 3 had wall motion abnormalities during the initial study. All of these patients demonstrated wall motion abnormalities at rest after the second study, however only 7 of 18 demonstrated abnormalities during the exercise study. The results indicate that resting left ventricular ejection fraction declines after doxorubicin treatment. Exercise radionuclide angiography may not increase diagnostic accuracy for the detection of doxorubicin related cardiotoxicity. Regional wall motion abnormalities occur with a relatively high incidence following doxorubicin therapy, more readily detectable at rest. However, the exercise study can distinguish doxorubicin related wall motion abnormalities from those due to coronary artery disease.

Adolescent↗
PubMedDate not supplied

Merits and limitations of radionuclide approaches to viability and future developments.

Radionuclide imaging approaches have proved useful for the noninvasive identification of a potentially reversible impairment of contractile function in human myocardium. Foremost among these approaches are (1) the thallium 201 uptake, redistribution, and reinjection technique and (2) the evaluation of blood flow and metabolism with positron emission tomography (PET). Both general approaches appear equally accurate in predicting the postrevascularization outcome of regional contractile function. In patients with severely depressed left ventricular function who are likely to benefit most from viability assessments, the available evidence suggests that the metabolic approach with PET outperforms the more conventional approach with 201Tl. Several investigations have suggested that PET can identify those patients with a low probability of long-term survival, as well as patients in whom revascularization will reduce mortality rates, improve global left ventricular function, and relieve related symptoms of congestive heart failure. Moreover, several new radionuclide techniques are currently emerging. They probe key points of viable myocardium, such as residual oxidative metabolism, fatty acid uptake and oxidation, membrane function, and cellular homeostasis. Although initial observations have been encouraging, further validation and especially testing in those patients in whom viability assessment is clinically critical will be required. These new approaches may also offer new insights into the mechanisms of reversible contractile dysfunction in the human myocardium.

Carbon Radioisotopes↗