Extraction of long-chain fatty acids in isolated rat heart during acute low-flow ischemia.

UNLABELLED: Although beta-oxidation of fatty acids is suppressed rapidly during ischemia, the behavior of fatty acid extraction at different flow rates is incompletely understood. This study assessed the relationship between flow and extraction of (123)I-iodophenylpentadecanoic acid (IPPA) in the isolated heart model, especially at low flow. METHODS: Isolated hearts from male Wistar rats (n = 15) were subjected to retrograde perfusion with constant flow (Krebs Henseleit solution containing 10 mmol/L glucose). A latex balloon in the left ventricle allowed isovolumetric contractions and ventricular pressure measurements. The extraction of (123)I-IPPA was assessed with the indicator dilution technique and (99m)Tc-albumin as the intravascular reference. The flow was either increased from the control flow (8 mL/min) until 300% or reduced until 10%. (123)I-IPPA extraction was measured three times before and 10 min after flow alteration. The tracer uptake was estimated from the product of net extraction and flow. RESULTS: The mean (123)I-IPPA extraction at the control flow (third measurement) was 51.6% +/- 2.8%. Between flow rates of approximately 25% and 300%, (123)I-IPPA extraction increased exponentially at decreasing flow rates. At flow rates < or =25% of the control flow, (123)I-IPPA extraction was exponentially higher than predicted. (123)I-IPPA uptake and flow changed largely in parallel. During low flow, the rate-pressure product showed the expected decline (perfusion-contraction matching). CONCLUSION: The extraction of (123)I-IPPA is preserved and slightly increased (relative to flow) during acute low-flow ischemia.

Immunoscintigraphy of the bone marrow: normal uptake values of technetium-99m-labeled monoclonal antigranulocyte antibodies.

UNLABELLED: The aim of our study was to determine the normal range of the 99mTc-labeled anti-NCA 95 antigranulocyte antibody (AGAb) uptake in the bone marrow using the sacroiliac-to-background uptake ratio in the posterior view. METHODS: We made 169 planar bone marrow scans on 162 patients who were each injected with 555 MBq AGAb. Fifty patients with the diagnosis of infection/pyrexia of unknown origin (PUO) and with completely normal bone marrow scintigraphy were defined as the normal group. Uptake ratios were calculated drawing irregular regions of interest around the sacroiliac and a background area, respectively. RESULTS: The normal group revealed a mean uptake ratio of 7.3 +/- 2.3 (range 4.4-12.6). Similar uptake ratios were obtained in patients with the primary diagnosis of infection/PUO and bone marrow extension (7.4 +/- 2.2, range 4.2-11.7), suggesting that the bone marrow reacts on infection primarily by extension into the periphery, without any significant increase of the activity of the central hemopoietic/granulopoietic bone marrow. Mean uptake ratios also were not significantly different in patients with normal bone marrow scintigraphy and the primary diagnosis of solid malignant tumors, lymphomas and plasmacytomas, and in patients with focal lesions visible on bone marrow scintigraphy (soft tissue inflammation or cold lesions in the bone marrow but with normal sacroiliac regions). Mean uptake ratios in the normal group were significantly age related, amounting to 8.5 +/- 1.8, 7.5 +/- 1.9 and 6.1 +/- 2.0 in patients younger than 40 yr, between 40 and 59 yr, and 60 yr or older, respectively (p = 0.0025). The method revealed good inter- and intraobserver agreement with correlation coefficients of about r = 0.90 and r = 0.95, respectively. Inter- and intraobserver coefficients of variation were 6.6% and 4.6%, respectively. CONCLUSION: Determination of the bone marrow uptake ratio is simple and reproducible. The normal values established in this study were age dependent, which has to be considered when interpreting bone marrow uptake ratios. The presence of infection/PUO, solid malignant tumors, lymphomas and plasmacytomas does not seem to alter the AGAb uptake ratio significantly. The most important application of the quantitative analysis of bone marrow scintigraphy could be the diagnosis and follow-up of diseases with depression of the central hemopoietic activity.

Iodine-123-iodo-lisuride SPECT in Parkinson's disease.

UNLABELLED: Recently, [123I]iodo-lisuride was synthesized for possible applications in SPECT studies. The purpose of this investigation was to compare the striatal binding and kinetics of this radioligand in patients with Parkinson's disease and normal controls. METHODS: Six patients with Parkinson's disease and three normal controls were examined. After intravenous injection of 111 MBq [123I]iodo-lisuride, sequential SPECT examinations at 20, 40, 80 and 120 min were performed. For each SPECT series the basal ganglia-to-cerebellum ratio of tracer accumulation was calculated. In one patient a repeat SPECT examination was undertaken under identical conditions to test the reproducibility of the procedure. In two other patients a second SPECT examination was performed after injection of cold lisuride as a receptor saturation study. In addition, the time course of the radioactivity was measured in the plasma and red blood cells in each individual. RESULTS: In both patients and controls, the highest tracer accumulation was found within the striatum. The basal ganglia-to-cerebellum ratio was 1.182 and 1.303 at 20 min, 1.353 and 1.450 at 40 min, 1.490 and 1.533 at 80 min, 1.550 and 1.583 at 120 min for patients and controls, respectively, which was not statistically different. In the saturation study, 50 micrograms and 100 micrograms cold lisuride led to a 28% and 33% reduction, respectively, of the basal ganglia-to-cerebellum ratio at 120 min. The ligand showed a rapid decline in plasma and red blood cells. The percent injected dose per liter was calculated to be 1.6 and 0.9, respectively, for plasma and red blood cells at 20 min. CONCLUSION: Iodine-123-iodo-lisuride SPECT seems useful for imaging intact striatal dopamine D2 receptors in patients with Parkinson's disease and may provide clinically relevant information for quantitative assessment of the availability and integrity of dopamine D2 receptors.

Combined dipyridamole and dobutamine echocardiography in myocardial hibernation: comparison with thallium uptake in patients after percutaneous transluminal coronary revascularization under circulatory support.

OBJECTIVE: To investigate the specificity and sensitivity of the combination of dipyridamole and dobutamine echocardiography for predicting functional recovery in patients with reduced ventricular function after coronary angioplasty. METHODS: Twenty-five patients, mean (SD) age 60.8 (10) years, with previous myocardial infarction (> 3 months), angiographically assessed coronary artery disease, and resting regional dysfunction (left ventricular ejection fraction < 35%) were studied. They underwent rest-redistribution thallium Tl-201 single photon emission computed tomography, and low-dose pharmacologic stress echocardiography with dobutamine (up to 10 microg/kg per minute), ultra low-dose dipyridamole (0.28 mg/kg over 4 minutes), and combined dipyridamole-dobutamine administration. RESULTS: The rate of agreement between Tl-201 and stress echo was 59% for dipyridamole, 62% for dobutamine, and 71% for combined dipyridamole-dobutamine (P <.05 vs dipyridamole and vs dobutamine). Combined dipyridamole-dobutamine showed a higher sensitivity (89%) than Tl-201, dobutamine, or dipyridamole (84%, 78%, and 80%). Specificity was lower for functional recovery prediction with Tl-201 (60%) compared with dobutamine (89%), dipyridamole (90%), and combined dipyridamole-dobutamine (91%). CONCLUSION: Thallium is more sensitive than dipyridamole or dobutamine; the sensitivity gap is filled with combined dipyridamole-dobutamine. Pharmacologic stress echocardiography is more specific than Tl-201 scintigraphy.

Echocardiographic AV-interval optimization in patients with reduced left ventricular function.

BACKGROUND: Ritter's method is a tool used to optimize AV delay in DDD pacemaker patients with normal left ventricular function only. The goal of our study was to evaluate Ritter's method in AV delay-interval optimization in patients with reduced left ventricular function. METHODS: Patients with implanted DDD pacemakers and AVB III degrees were assigned to one of two groups according to ejection fraction (EF): Group 1 (EF > 35%) and Group 2 (EF < 35%). AV delay optimization was performed by means of radionuclide ventriculography (RNV) and application of Ritter's method. RESULTS: For each of the patients examined, we succeeded in defining an optimal AV interval by means of both RNV and Ritter's method. The optimal AV delay determined by RNV correlated well with the delay found by Ritter's method, especially among those patients with reduced EF. The intra-class correlation coefficient was 0.8965 in Group 1 and 0.9228 in Group 2. The optimal AV interval in Group 1 was 190 +/- 28.5 ms, and 180 +/- 35 ms in Group 2. CONCLUSION: Ritter's method is also effective for optimization of AV intervals among patients with reduced left ventricular function (EF < 35%). The results obtained by RNV correlate well with those from Ritter's method. Individual programming of the AV interval is fundamentally essential in all cases.

[Septal myocardial perfusion in complete left bundle branch block: case report and review of the literature]. / Septale Myokardperfusion bei komplettem Linksschenkelblock: Kasuistik und Literaturübersicht.

Myocardial scintigraphy was performed three times in a 55-year-old woman with left bundle branch block (LBBB). A significant LAD stenosis had been excluded by coronary angiography. The first scintigraphy was performed with Tc-99m sestamibi after submaximal bicycle exercise and revealed a septal perfusion deficit. This deficit could not be reproduced in the following examinations after pharmacological stress testing with dipyridamole using both Tl-201 and Tc-99m sestamibi. Perfusion at rest assessed with Tl-201 was normal in all studies. It is concluded that pharmacological stress testing with dipyridamole is to be preferred in patients with LBBB. With respect to the accuracy of myocardial perfusion imaging the choice of the radiopharmaceutical plays a less important role.

[Lung activity in 201Tl myocardial scintigraphy: distribution and correlation with hemodynamic parameters]. / Die Lungenaktivität in der 201Tl-Myokardszintigraphie: Verteilung und Korrelation zu hämodynamischen Parametern.

UNLABELLED: The aim of this study was 1. to investigate whether the pulmonary activity in 201Tl myocardial scintigraphy can be accurately quantified from the anterior SPECT projection, 2. to determine the pattern of the intrapulmonary Tl distribution, and 3. to assess the influence of parameters of left ventricular function on the lung/heart ratio (LHR). Scintigraphic images of 85 patients were analysed. In 24 patients planar anterior imaging of the thorax was performed in addition to myocardial SPECT, in 41 patients radionuclide ventriculography was performed within 4 weeks after Tl scintigraphy. IN CONCLUSION: 1. pulmonary Tl-content can be quantitated from the anterior SPECT projection with sufficient accuracy, 2. a lower thallium activity was registered over the apical part of the lung as compared to the basal part, and 3. in the multiple regression analysis the left ventricular ejection fraction (LVEF) during exercise and heart rate during exercise (HRex) exhibited the strongest relation to LHR. After correction with regard to HRex the elevated LHR points to a pathological LVEF during exercise.

Combined thallium-201 and dynamic iodine-123 iodophenylpentadecanoic acid single-photon emission computed tomography in patients after acute myocardial infarction with effective reperfusion.

BACKGROUND: Considerable derangements of energy metabolism are to be expected during ischemia and reperfusion. In ischemic myocardium, the oxidative degradation of carbohydrates is shifted toward the anaerobic production of lactate and the oxidation of fatty acids is suppressed. HYPOTHESIS: The aim of this study was to examine the uptake and metabolism of iodine-123 (123I) iodophenylpentadecanoic acid (IPPA) in stunned myocardium. METHODS: In 15 patients, SPECT with 201Tl and 123I IPPA as well as echocardiography with low-dose dobutamine stimulation were performed 12 +/- 5 days after myocardial infarction with reperfusion. Follow-up echocardiography was carried out 24 +/- 8 days later for documentation of functional improvement. Uptake of 201Tl and 123I IPPA were obtained in five left ventricular segments, and dynamic SPECT imaging was used for calculation of the fast and the slow components of the biexponential myocardial 123I IPPA clearance. RESULTS: Wall motion improved in 14 of 26 dysfunctional segments (54%). Stunned segments were characterized by a reduced 123I IPPA extraction, a shorter half-life of the fast, and a longer half-life of the slow clearance component. All parameters of the combined 201Tl/123I IPPA study predicted functional recovery with similar accuracies (area under the receiver operator characteristic curves between 0.68 and 0.76; p = NS). Analysis of 201Tl uptake alone could not predict functional recovery in this study. CONCLUSIONS: Stunned myocardium is characterized by a disturbance of fatty acid metabolism. For prediction of functional improvement, 123I IPPA imaging added significant diagnostic information.

Washout and redistribution between immediate and two-hour myocardial images using technetium-99m sestamibi.

The aim of this study was to assess whether a clinically relevant change in myocardial sestamibi activity could be documented within the first 120 min following injection (p.i.). In 17 patients planar anterior imaging of the heart was performed 5 min and 120 min p.i. During this time interval, mean decay-corrected myocardial activity declined to 77.9% +/- 9.7% after stress and to 85.7% +/- 7.9% after injection at rest (P < 0.05). In 19 patients with angiographically documented coronary artery disease, single-photon emission tomography was performed 5 min and 120 min after injection at maximum stress. For analysis, sestamibi activity was scored semiquantitatively in six left ventricular segments. Furthermore, sestamibi uptake was assessed quantitatively using a circumferential profile method. In 35 of 114 segments the score improved within 120 min p.i. (early fill-in); in these segments relative sestamibi activity rose from 69.9% +/- 22.5% to 74.5% +/- 20.8% (P < 0.01). In five patients this early fill-in was the only sign of exercise-induced hypoperfusion. In 7 of 114 segments the score deteriorated 120 min p.i. (early tracer washout); in these segments relative sestamibi activity declined from 85.6% +/- 9.9% to 80.1% +/- 10.7% (P < 0.02). In three of four patients with early tracer washout the corresponding coronary artery was significantly narrowed. In conclusion, a global myocardial sestamibi washout was registered within the first 120 min after injection. A fill-in of initial defects as well as an early tracer loss could be detected in a relevant number of patients with chronic coronary artery disease during the first 2 h p.i.(ABSTRACT TRUNCATED AT 250 WORDS)