17-iodoheptadecanoic-acid and Coronary-Disease

Due to its advantageous nuclear physical properties iodine-123 is an excellent label for radiopharmaceuticals very well suited for measurements by gamma-cameras and single-photon emission tomography. The development of 123I-radiopharmaceuticals should be based on a clear biochemical concept, reliable labelling procedures and careful pharmacokinetic studies in order to evaluate the physiological behaviour of the radioiodinated compounds being analogues of metabolic substrates. The development of 123I-labelled fatty acids and biogenic amines clearly proved the successful use of 123I for labelling compounds applied in medical diagnosis.

Topics: Amphetamines; Animals; Brain; Cerebral Arterial Diseases; Coronary Disease; Fatty Acids; Heart; Humans; Iodine Radioisotopes; Iodobenzenes; Iofetamine; Isotope Labeling; Mice; Middle Aged; Rats; Tomography, Emission-Computed

Ten patients underwent myocardial scintigraphy with 123I-iodo-heptadecanoic acid (HDA), which was injected in the last minute of maximal exercise testing. Six of the patients were rescanned following percutaneous transluminal coronary angioplasty. All ten patients underwent full coronary angiography. There were visible perfusion defects on the static images in 74% of the myocardial areas which were supplied by an artery with a stenosis greater than 75%. The mean half life recorded from areas distal to an arterial stenosis of at least 90% (35.69 min +/- 41.25 min), was longer than the expected normal mean (18.85 min +/- 3.35 min). However, the difference was not statistically significant. The static images changed in some patients following angioplasty, however there was no consistent alteration in the half lives. It was concluded that HDA is a suitable agent for investigating myocardial perfusion, but that the half life cannot be measured adequately for clinical purposes with a planar imaging system.

Topics: Angioplasty, Balloon; Coronary Disease; Coronary Vessels; Fatty Acids; Heart; Humans; Iodine Radioisotopes; Radionuclide Imaging

Myocardial time-activity curves can be described by two or more parameters. To establish the optimal curve fitting method 33 myocardial time-activity curves were analyzed with different curve fitting methods: monoexponential, biexponential and monoexponential plus constant. A background correction was not applied. Biexponential curve fitting resulted in redundancy of parameters. Optimal curve fitting was obtained with monoexponential plus constant. The constant represents the background activity together with the stored radiolabelled lipids and the half-time value represents the wash-out of radioiodide from the myocardium. A strong relation was found between the constant and the half-time value: small errors in the determination of the constant (background activity) resulted in considerable errors of the half-time value. It is concluded that optimal analysis of a myocardial time-activity curve can be performed with a monoexponential plus constant without earlier correction for background activity.

Topics: Coronary Disease; Fatty Acids; Half-Life; Humans; Iodine Radioisotopes; Myocardium; Radionuclide Imaging

Optimal fitting of a myocardial time-activity curve is accomplished with a monoexponential plus a constant, resulting in three parameters: amplitude and half-time of the monoexponential and the constant. The aim of this study was to estimate the precision of the calculated parameters. The variability of the parameter values as a function of the acquisition time was studied in 11 patients with cardiac complaints. Of the three parameters the half-time value varied most strongly with the acquisition time. An acquisition time of 80 min was needed to keep the standard deviation of the half-time value within +/- 10%. To estimate the standard deviation of the half-time value as a function of the parameter values, of the noise content of the time-activity curve and of the acquisition time, a model experiment was used. In most cases the SD decreased by 50% if the acquisition time was increased from 60 to 90 min. A low amplitude/constant ratio and a high half-time value result in a high SD of the half-time value. Tables are presented to estimate the SD in a particular case.

Topics: Coronary Disease; Fatty Acids; Half-Life; Humans; Iodine Radioisotopes; Myocardium; Radionuclide Imaging

We have evaluated 123I-heptadecanoic acid for myocardial scintigraphy in the diagnosis of coronary heart disease by comparing the results obtained with it in subject groups with high and low probabilities of disease. We conclude that although some patients in the former group can be identified, the test is neither sufficiently sensitive nor specific for routine clinical use.

Topics: Adult; Aged; Coronary Disease; Fatty Acids; Female; Humans; Iodine Radioisotopes; Male; Middle Aged; Radionuclide Imaging

In an attempt to evaluate the dynamics of fatty acid metabolism after aortocoronary bypass grafting (ACBG), ten patients were investigated after ACBG by 123I-HDA myocardial scintigraphy. Tracer kinetics were followed for 90 min and compared to those of 36 nongrafted patients with different underlying heart diseases, including healthy volunteers. Regional analysis and monoexponential curve fitting were used to evaluate t1/2 (half-life of the early period of tracer elimination); biexponential curve analysis was used to calculate Ca/Cb, the ratio of a fast and a slow component of tracer elimination. Rest and stress MUGA-RNV served as discriminating parameters to discern between patient groups with normal and abnormal ventricular function. Group I (normal controls) encompassed ten patients with normal ventricular function, including three after ACBG, and group II seven patients after ACBG and with abnormal ventricular function. Group III had coronary artery disease (CAD) documented by angiography, and group IV by prior myocardial infarction (MI). Group V included patients with cardiomyopathy (CMP). Regional analysis of group II revealed no significant differences to control regions (Gr I) for t1/2 or Ca/Cb, but showed for Ca/Cb a nonsignificant shift toward group III values. However, group II differed significantly from group III and V. Three patients with normal ventricular function after ACBG showed elimination values that were all well within the range of completely normal individuals. Thus our data support the assumption that a normal function is indicative of a normal metabolism. Following myocardial fatty acid metabolism during rest might be a helpful noninvasive tool for etiologic differentiation of disturbed ventricular function.

Topics: Coronary Artery Bypass; Coronary Disease; Fatty Acids; Fatty Acids, Nonesterified; Heart; Humans; Iodine Radioisotopes; Kinetics; Myocardium; Tomography, Emission-Computed

This study was undertaken to elucidate if the myocardial elimination rate of the radioactivity after administration of radioiodinated heptadecanoic acid was related to beta-oxidation of the fatty acid or related to washout of free radioiodide. In samples of normal and ischaemic myocardium the distribution of the radioactivity over free radioiodide, heptadecanoic acid and lipids was determined. In normal myocardium the major component was free radioiodide, only a small percentage being heptadecanoic acid. In ischaemic myocardium more radiolabelled lipids were present and less free iodide when compared with normal myocardium. The percentage heptadecanoic acid was slightly increased. It is concluded that radioiodinated heptadecanoic acid behaves like the natural analogues regarding uptake and distribution. However, washout of free radioiodide determines the elimination rate as observed during a scintigraphic study.

Topics: Animals; Blood Pressure; Coronary Disease; Dogs; Electrocardiography; Fatty Acids; Heart; Iodine Radioisotopes; Kinetics; Lipid Metabolism; Male; Myocardium; Radionuclide Imaging

In an experimental study, we evaluated the uptake of (131I)-17-iodo heptadecanoic acid (131I-HDA), (125I)-15-4 (4-iodophenyl) pentadecanoic acid (125I-PPA) and thallium-201 (201Tl) in the dog heart. Twenty dogs were studied and divided into 3 groups: in group A, 10 dogs (4 normal, 6 with coronary artery occlusion) were studied with 131I-HDA and 201Tl; in group B, 5 dogs (with occlusion) received 125I-PPA and 201Tl; and in group C, 5 dogs (with occlusion) were studied with 125I-PPA and 131I-HDA. Two min after administration of the compounds the hearts were excised and stored in formaldehyde. After sectioning of the left ventricle, total uptake was counted and expressed in percentage of injected dose. Uptake in the normal myocardium (group A) was 4.2 +/- 0.6% for 131I-HDA and 4.6 +/- 0.7% for 201Tl; in the occluded dog hearts (group A) we measured values of 2.6 +/- 0.4% for 131I-HDA (p less than 0.001) and 3.4 +/- 0.6% for 201Tl (p less than 0.01). Uptake of 131I-HDA, 125I-PPA and 201Tl in groups B and C was not significantly different: group B, 125I-PPA 2.8 +/- 0.8% and 201Tl 2.5 +/- 0.5%; group C, 125I-PPA 1.9 +/- 0.7% and 131I-HDA 1.6 +/- 0.6%. Moreover, regional distribution of both iodinated fatty acids was quite comparable with the distribution of 201Tl. We conclude that 131I-HDA and 125I-PPA show similar uptake as 201Tl and are distributed according to coronary artery perfusion, which underscores their value as myocardial imaging agents.

Topics: Animals; Coronary Disease; Dogs; Fatty Acids; Iodine Radioisotopes; Iodobenzenes; Male; Myocardium; Radioisotopes; Radionuclide Imaging; Thallium

Topics: Animals; Coronary Disease; Dogs; Fatty Acids; Fatty Acids, Nonesterified; Iodine Radioisotopes; Iodobenzenes; Male; Myocardium; Palmitic Acids

I-123-omega-heptadecanoic acid (HDA) was evaluated for myocardial scanning in 59 healthy volunteers and 133 patients, using a 7-pinhole collimator. Early (uptake) and late (retention) images were compared visually. Regional HDA elimination was also followed semiquantitatively based on the calculation of a retention-over-uptake ratio, R(phi), derived from the maximal counts/pixel in 60 midventricular slice sectors. The healthy heart concentrated HDA homogeneously in all segments with no difference between early and late images. The minimal R(phi), taken as representative of that myocardium with the best function, was unchanged after maximal ergometer stress and with dipyramidole-induced hyperperfusion. A circumscribed decreased HDA uptake is the clear-cut criterion for an abnormal finding. HDA tomography of the myocardium had an 86% sensitivity for myocardial infarcts (MIs) up to 4 wk old, and 83% for myocardial scars (MSs). Comparing early and late tomograms, we find a cool-warm sequence more often with acute and subacute MIs. A cool-cool or a cold-cold sequence dominated with MSs. HDA tomoscintigraphy cannot replace TI-201 for the evaluation of regional coronary reserve in coronary heart disease.

Topics: Adult; Aged; Coronary Disease; Evaluation Studies as Topic; Fatty Acids; Female; Heart; Humans; Iodine Radioisotopes; Male; Middle Aged; Myocardial Infarction; Myocardium; Radioisotopes; Radionuclide Imaging; Thallium; Tomography

In twenty patients with primary congestive cardiomyopathy (COCM) the patterns of accumulation and washout of the fatty acid analogue [17-123I]iodoheptadecanoic acid (I-123 HA) were studied. In contrast to patients with ischemic heart disease, where reduced I-123 HA accumulation was correlated with stenosis of the main coronary arteries, thus usually involving larger wall segments, the patients with COCM concentrated I-123 HA heterogeneously in small spotty segments throughout the entire left-ventricular myocardium. The regional washout half-times varied between 15.1 and 116.2 min. It seems that in patients with severe COCM the elimination half-times are more prolonged than in early stages of the disease. There was no correlation between the regional uptake and the elimination half-times. Sequential myocardial imaging with I-123 HA appears useful for noninvasively diagnosis of COCM.

Topics: Cardiomyopathies; Coronary Disease; Diastole; Fatty Acids; Half-Life; Heart; Heart Septum; Heart Ventricles; Humans; Iodine Radioisotopes; Myocardium; Radionuclide Imaging

To characterize externally detectable changes in the myocardial metabolism of free fatty acids (FFA) and glucose, which are associated with ischemia and cardiomyopathy, omega-123I-heptadecanoic acid (stearic acid analogue), 75Br-phenylpentadecanoic acid, and 3-0-11C-methyl-D-glucose were used as indicators. It could be demonstrated that in the metabolism of free fatty acids at least two different patho-physiological situations may exist. Disturbances in the mechanism of the accumulation of free fatty acids lead to a decrease of the amount of the free fatty acids which are available for energy production (these disturbances can be recognized as indicator accumulation defects). Disturbances associated with the mechanism of free fatty acid catabolism lead to a decrease of the ability of the myocardial cell to utilize the free fatty acids (these disturbances can be recognized as changes in indicator elimination rates). Whereas in ischaemic heart disease, the areas with altered FFA accumulation correlate with the areas of altered FFA-elimination, no correlation was found in the case of cardiomyopathy. The 11C-methylglucose seems to be an excellent indicator for the in-vivo assessment of the function of transport system in the myocardial cell membrane.

Topics: Animals; Carbon Radioisotopes; Cardiomyopathies; Coronary Disease; Fatty Acids; Fatty Acids, Nonesterified; Humans; Iodine Radioisotopes; Methylglucosides; Methylglycosides; Mice; Myocardium; Tomography, Emission-Computed

Topics: Cardiomyopathies; Coronary Disease; Fatty Acids; Heart; Humans; Iodine Radioisotopes; Middle Aged; Myocardium; Radionuclide Imaging

After intravenous administration of the stearic acid analogue [17-123I]iodoheptadecanoic acid (I-123 HA), myocardial metabolism was studied in ten normal individuals, eight patients with coronary artery disease and three patients with congestive heart failure. High-quality images were obtained in sequential scintigraphy of I-123 metabolically bound in myocardial tissue. Infarcted zones as well as ischemic regions are indicated by reduced tracer uptake. Iodine-123 in the blood pool and interstitial space consists mainly of radioiodide that is liberated by fatty-acid metabolism and was corrected for. Using the proposed correction not only are the images improved but the uptake and elimination of the I-123 in the myocardial cells can be followed. The average disappearance half-time of I-123 HA from the myocardium of normal persons was 24 +/- 4.7 min. In patients with coronary artery disease significant differences between myocardial regions were observed.

Topics: Adult; Aged; Coronary Disease; Fatty Acids; Fatty Acids, Nonesterified; Half-Life; Heart; Heart Diseases; Heart Failure; Humans; Iodine Radioisotopes; Male; Middle Aged; Myocardium; Radionuclide Imaging