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Biomedical subjects

A Gottschalk

Publications and source records attributed to A Gottschalk.

At least 127 records · Page 7Linked to original sources
PubMed1981

A miniature cadmium telluride detector module for continuous monitoring of left-ventricular function.

The authors describe a miniature cadmium telluride (CdTe) detector module for continuous monitoring of ventricular function using an equilibrium radionuclide blood-pool label. The detector and collimator are small, light, and suitable for direct attachment to the chest wall. Clinical studies in 18 patients using a prototype system demonstrated reasonably good correlation with left-ventricular ejection fractions (LVEF) determined by first-pass studies performed with a multicrystal scintillation camera (r = 0.74) and gated equilibrium studies performed with a computerized sodium iodide (Nal) probe (r = 0.76). The CdTe device may prove to be useful in patients in intensive and coronary care units as well as in ambulatory patients.

Adult↗
PubMed1981

Beat-to-beat left ventricular performance assessed from the equilibrium cardiac blood pool using a computerized nuclear probe.

The feasibility, accuracy and reproducibility of continuous beat-to-beat evaluation of left ventricular performance with a computerized nonimaging scintillation probe was assessed in 71 patients. This portable instrument has enough sensitivity to generate a real-time relative left ventricular volume curve using the labeled equilibrium blood pool without electrocardiographic gating. The probe was positioned at the left ventricular and background regions of interest using a systematic series of computerized algorithms and operator routines that were developed and standardized during the initial phase of this study. In each patient, left ventricular ejection fraction was calculated manually from the strip-chart recording in 10 consecutive sinus beats. Beat-to-beat left ventricular ejection fraction determined by the probe correlated well with first-pass studies obtained using a computerized multicrystal scintillation camera (r = 0.92). There was no systematic over- or underestimation, and the correlation was evident over a wide range of first-pass values (15-81%). There was excellent agreement between initial and repeat analyses (n = 58, r = 0.97) and between initial and repeat studies (n = 48, r = 0.94). The absolute variability of beat-to-beat ejection fraction measurements determined from all 710 beats was +/- 5.9% (expressed in ejection fraction units as +/- 2 SD). This technique should provide a reliable means of addressing pathophysiologic questions that require sampling of data directly on a beat-to-beat basis.

Diastole↗
PubMed1981

Imaging the inflammatory response to acute myocardial infarction in man using indium-111-labeled autologous platelets.

The feasibility of imaging the inflammatory response to acute transmural myocardial infarction in man using biologically active indium-111 (111In)-labeled autologous leukocytes was assessed in 36 patients. Indium-111 leukocytes (approximately 500 microCi) were injected i.v. 18-112 hours after the onset of chest pain. Cardiac imaging was performed 24 hours later with a mobile gamma camera. Twenty-one patients had positive images and 15 had negative images. The percent of positive images increased as the interval between infarction and 111In-leukocyte injection shortened; all patients injected within 24 hours of infarction had positive images. Patients with positive images were injected with 111In leukocytes earlier after infarction (mean +/- SEM, 43 +/- 4 vs 63 +/- 7 hours; p less than 0.05) and were younger (53 +/- 2 vs 65 +/- 3 years; p less than 0.05) than those with negative images. Several other parameters that could possibly have affected the imaging results were examined and were not significantly different in patients with positive and negative images. These included peak serum creatine kinase, location of infarction, incidence of pericarditis, use of antiinflammatory drugs (aspirin and indomethacin) or membrane-active antiarrhythmic drugs (lidocaine and procainamide), peripheral leukocyte count and cell labeling efficiency. The function of the labeled cell was similar in patients with positive and negative images. Six patients with acute infarction serving as controls and given free 111In oxine and six patients with stable coronary artery disease given 111In leukocytes all had negative cardiac images.

Acute Disease↗
PubMed1981

Indium-111-labeled human platelets: improved method, efficacy, and evaluation.

An improved method for labeling human platelets with In-111 oxine is described. The method used modified Tyrode's solution (MTS) as a labeling medium and allowed 86 +/- 7% incorporation of In-111 into platelets, which upon stimulation with ADP aggregated 66 +/- 15% of control platelets. This compared favorably with the 5% radioactivity uptake in plasma and the 36 and 55% aggregability of platelets labeled in saline and citrated saline, respectively. The influence of parameters affecting the platelet aggregability were examined. The studies revealed that excess of oxine (50 microgram oxine/1.6 x 10(9) platelets in 1 ml MTS), and centrifugation at greater than 1000 g, reduced platelet aggregability. Excess of oxine also caused a dose-dependent release of In-111 from platelets labeled either in MTS or in plasma, but 4 millimol EDTA did not. Release of In-111 upon aggregation of platelets labeled in either medium was negligible.

Blood Platelets↗
PubMed1980

Radionuclide assessment of right and left ventricular exercise reserve after total correction of tetralogy of Fallot.

First pass radionuclide angiocardiography under conditions of rest and exercise was utilized to evaluate a group of 16 postoperative patients who had undergone total surgical correction of tetralogy of Fallot. Functional data were related to thallium-201 myocardial imaging at rest, a noninvasive means of detecting right ventricular hypertrophy. All 16 patients were asymptomatic and 15 demonstrated normal right ventricular ejection fraction (equal to or greater than 45 percent) at rest. However, 13 patients manifested abnormal right ventricular ejection fraction responses to exercise (normal response is an absolute increment in an ejection fraction of 5 or greater percent). For the entire group, right ventricular ejection fraction at rest was 55 +/- 2 percent, whereas at exercise it was 52 +/- 2 percent (p = not significant). In contrast, left ventricular ejection fraction responses were normal in all patients. Thallium-201 imaging revealed substantial right ventricular uptake consistent with residual right ventricular hypertrophy, which was quantifiable in all patients. Thus, abnormalities in right ventricular performance during exercise may be detected readily by this radionuclide approach in these postoperative patients despite their asymptomatic clinical status and generally normal right ventricular performance at rest.

Adolescent↗
PubMed1980

Current status of ventilation-perfusion imaging.

The major clinical use of ventilation-perfusion (V/Q) scintigraphy is for the diagnosis of pulmonary embolism (PE). Accurate diagnosis of PE is essential since effective treatment is available but involves some risk to the patient. The scintigraphic characteristics of PE are segmental perfusion defects in lung that is normally ventilated and normal on the radiograph. The inherent shortcoming of perfusion scintigraphy is its lack of specificity. Combining a ventilation study with perfusion imaging improves the diagnostic specificity of lung scintigraphy. Xenon-133 is currently the most commonly used radionuclide for routine ventilation studies; a long washout technique is more sensitive than single-breath imaging when this radionuclide is used. We obtain preperfusion xenon-133 ventilation studies with a 4-min rebreathing equilibrium phase and a long 5-min washout phase to obtain maximum information. It is imperative that V/Q studies be interpreted with a current high quality chest radiograph. Interpretation of V/Q studies for PE is perhaps best done by assigning a probability diagnosis, since rarely is absolute specificity possible. This article details the criteria we use for these probability determinations.

Adult↗
PubMed1980

Problems in the scintigraphic detection of osteomyelitis in children.

99mTc-pyrophosphate studies in 21 children with acute hematogenous osteomyelitis were compared with radiographic, clinical and surgical findings. Eleven 99mTc studies revealed obvious abnormalities, four showed subtle abnormalities, two were misleading, and four were normal. No consistent explanation for the lack of positive radionuclide findings was found. We concluded that pediatric osteomyelitis presents a spectrum of scintigraphic appearances and interpretation is often difficult.

Acute Disease↗
PubMed1980

Ordering patterns and clinical impact of cardiovascular nuclear medicine procedures.

We analyzed the ordering and impact of the first 171 fee-for-service cardiovascular nuclear medicine procedures at one hospital. The ordering physicians said 72% of the study results were useful and 28% contributed to changes in patient management. Experienced cardiology reviewers, however, felt that only 65% of studies were appropriately ordered, that 97% of appropriately ordered studies provided potentially useful information, and that 12% of all studies made important contributions to appropriate changes in patient management. The revieweres were most likely to rate exercise thallium procedures and procedures ordered by physicians from distant hospitals as being appropriately ordered and having important clinical impact. We conclude that (1) ordering physicians and revieweres may disagree substantially in their estimates of the impact of a diagnostic test; and (2) although a test may yield important information in appropriate patients, its total clinical impact will depend on how often it is suitably ordered and used.

Cardiovascular Diseases↗
PubMed1980

Right and left ventricular exercise performance in chronic obstructive pulmonary disease: radionuclide assessment.

Right and left ventricular pump performance was assessed at rest and during upright bicycle exercise in 30 patients with chronic obstructive pulmonary disease and in 25 normal control subjects. Right ventricular and left ventricular ejection fractions were ascertained noninvasively using first-pass quantitative radionuclide angiocardiography. The normal ventricular response to exercise was at least a 5% absolute increase in the ejection fraction of either ventricle. In patients the predominant cardiac abnormality involved performance of the right ventricle. Right ventricular ejection fraction was abnormal at rest in eight patients. Twenty-three patients demonstrated an abnormal right ventricular response to submaximal exercise. Airway obstruction and arterial hypoxemia were significantly more severe in patients with abnormal right ventricular exercise reserve than in those with normal reserve. Abnormal left ventricular performance was infrequent either at rest (four patients) or during exercise (six patients). Thus, this radionuclide technique allows noninvasive assessment of biventricular exercise reserve in chronic obstructive pulmonary disease.

Adult↗
PubMed1980

A simplified method of selective spleen scintigraphy with Tc-99m-labeled erythrocytes: clinical applications. Concise communication.

We report our initial clinical experience with a simplified spleen-imaging technique that requires no red cell washing or special kits. Thirty minutes after an injection of "cold" pyrophosphate containing 0.5 mg of stannous chloride or fluoride, a blood sample is drawn, 2 mCl of pertechnetate (Tc-99m) are added, the sample is incubated at 49--50 degrees for 35 min, and then reinjected into the patient. We have studied 13 patients with this technique, and have found it useful in the clarification of various questionable splenic abnormalities found on the sulfur colloid scan, as well as in the detection of splenosis.

Adult↗
PubMed1979

Differences in lipid and lipoprotein concentrations of capillary and venous blood samples.

The concentrations of lipids and lipoproteins measured in capillary blood serum taken from young adults were significantly lower than in venous blood, although they correlated satisfactorily. These differences may reflect differences in the morphological and hemodynamic conditions existing either in large veins or in the peripheral circulatory system. It was concluded that venous and capillary blood serum cannot be used interchangeably for these estimations.

Adult↗
PubMed1979

Serial assessment of doxorubicin cardiotoxicity with quantitative radionuclide angiocardiography.

We measured cardiac performance sequentially, using quantitative radionuclide angiocardiography to estimate left ventricular ejection fraction in 55 patients receiving doxorubicin for treatment of cancer. With final doxorubicin dosages greater than 350 mg per square meter, the lowest ejection fraction measured was significantly less than the initial determination. Five patients had severe cardiotoxicity (congestive heart failure). All had an ejection fraction of less than 30 per cent at the time of heart failure, and demonstrated moderate cardiotoxicity (a decline in ejection fraction by at least 15 per cent to a final value of less than 45 per cent) before clinical manifestations. Six patients with moderate toxicity in whom doxorubicin was discontinued did not have heart failure or a further decline in ejection fraction during the follow-up period. Moderate toxicity was continued, but mild toxicity (decline of ejection fraction by greater than 10 per cent, noted in 11 patients) was not well predicted. The assessment of radionuclide left ventricular ejection fraction during doxorubicin therapy may make it possible to avoid congestive heart failure.

Adult↗