Biomedical subjects
Publications and source records attributed to M Comet.
15-(p-Iodophenyl) pentadecanoic acid labelled with carbon-14 in the carboxyl group is obtained with good yields in five steps from [14C]NaCN, starting from 14-bromo 1-phenyl tetradecane 2. Specific radioactivity: 0.019 mCi/mg, 8.45 mCi/mmol; radiochemical yield: 74.6%.
The intracellular and subcellular distribution of 16-(123I)-iodo-9-hexadecenoic acid were studied in isolated rat hearts, perfused with or without glucose. At various time intervals after injection, cardiac lipids were extracted and the activity was determined for all fractions and all lipid classes. The total cardiac activity was maximal within 1 min postinjection and most of the activity was in the aqueous phase. The presence of glucose in the perfusion medium induced an increase of total cardiac and organic fraction activities. In the latter fraction, activity was very low for FFA, but high for triglycerides (TG), and especially polar lipids. The presence of an exogenous substrate, led to a more active esterification of fatty acids. Coronary effluent analysis showed, in the hydrophilic phase, a lower activity spike in the presence than in the absence of glucose. In the mitochondrial fraction most activity occurred in the organic phase, especially as polar lipids. In the nonmitochondrial fraction, activity was much higher in the aqueous phase. At 90 s postinjection of 1-14C-palmitic acid, over 80% of the myocardial activity was found in the hydrophilic fraction, which indicates, as for the iodo-fatty acid (IFA), an immediate and important oxidation, especially without glucose. These data seem to prove that IFA is taken up by the myocardial cell, subsequently enters the mitochondria and, without an early deiodination, is oxidized with iodide release. Changes in IFA metabolism, consecutive to modifications of glucose concentration in the perfusion medium can be observed by external detection of the myocardial activity curve. Omega-Iodinated fatty acids do not undergo a nonspecific deiodination and are therefore well suited for an external study of myocardial metabolism.
External counting, intracellular and subcellular distribution of (16 123I) iodohexadecenoic acid are studied on isolated rat hearts perfused with or without glucose. The presence of an exogenous substrate reduces the fatty acid oxidation and induces an increase of total cardiac and organic fraction activities. In this fraction, activity is very low for free fatty acids, but high for triglycerides and especially for polar lipids. The presence of an exogenous substrate leads to a more active esterification of fatty acids. Coronary effluents analysis shows, in the hydrophilic phase, a lower activity rebound in the presence of glucose. In the mitochondrial fraction, activity is mostly in the organic phase, as polar lipids especially. In the non-mitochondrial fraction, activity is much higher in the aqueous phase. 90 s p.i. of (l 14C) palmitic acid, over 80% of the myocardial activity is found in the hydrophilic fraction, which indicates--as for the iodo fatty acid (IHA)--an immediate and important oxidation, especially without glucose. These data seem to prove that IHA is taken up by the myocardial cells, enters the mitochondria where it is, without an early deiodination, oxidized with iodide release. IHA metabolic changes can be seen on the external detection myocardial activity curve. Omega iodinated fatty acids do not undergo a nonspecific important deiodination and are therefore well adapted to an external study of myocardial metabolism.
The aims of this comparative study by vectorcardiography and myocardial scintigraphy in the topographical analysis of primary inferior and/or posterior wall infarction, were: to obtain data confirming the value of identifying true posterior wall infarction; to confirm the diagnostic value of vectorcardiography in this condition. The patients in this retrospective study were admitted to hospital for primary inferior and/or posterior wall infarction and underwent vectorcardiography and myocardial scintigraphy either with Thallium 201 (137 patients) or 99m Technetium (88 patients) in the acute phase. The scintigraphies of all patients included showed hypofixation compatible with inferior and/or posterior infarction as this was used as the topographical reference. The results of vectorcardiography and myocardial scintigraphy were concordant in 164 of the 225 patients (72.8%), 18 with true posterior infarction [%), 110 with inferior wall infarction (48.8%) and 36 with postero-inferior wall infarction (16%). The results were discordant in 61 patients (27.1%); infarcts of the inferior or posterior walls according to one technique, were observed on the posterior or inferior walls with the other. The majority of these cases had postero-inferior wall changes on vectorcardiography and inferior wall infarction alone on scintigraphy (35 patients: 15.5%). The specificity of the vectorcardiographic signs of true posterior wall infarction remained satisfactory.(ABSTRACT TRUNCATED AT 250 WORDS)
The methyl-branched fatty acids, if radioiodine labelled in alpha position, are potentially adapted to a selective study of FA myocardial uptake. To determine the position and the number of methyl radicals that are necessary to obtain a maximal uptake and a minimal degradation, we measured time-activity evolution of isolated and perfused rat hearts after an injection of iodinated fatty acids which are mono- or dimethylated in alpha or beta position. Except for dimethyl fatty acid, the uptake is similar for all fatty acids studied to that of the straight chain analogue; beta mono- or dimethyl fatty acids seem best adapted to a study of the uptake because alpha monomethyl fatty acids undergo a metabolic degradation and alpha mono- and dimethyl fatty acids induce ventricular fibrillations.
UNLABELLED: Between January 1983 and May 1984, 104 patients with no known cardiac pathology were referred by their cardiologist for diagnosis of chest pain. They all underwent coronary angiography which was used as the reference investigation and the following sequential Bayes' analysis was performed. The percentage probability of coronary artery disease was estimated from clinical date (age, sex, characteristics of the chest pain subdivided into 3 groups); an exercise ECG was performed in all cases (classified as positive, negative or non diagnostic); if the probability of coronary artery disease was greater than 95% (or less than 5%) after exercise stress testing the patients was diagnosed as having (or not having) coronary artery disease. If the probability was between 6 and 94% the patient underwent Thallium myocardial scintigraphy (Thallium dipyridamole; analysis on a colour television screen); the coronary risk probability before Thallium was that calculated after exercise stress testing. If after myocardial scintigraphy the coronary risk remained between 6 and 94%, an exercise angioscintigraphy was performed and interpreted in the same way. The clinical and complementary date was analysed on a mini-computer, the values of the sensitivity and specificity of the tests used for the calculation of the probability of coronary artery disease were those previously published by our group. RESULTS: 31/88 (35%) of patients were classified in the 5% risk groups after exercise stress testing (24 coronary artery disease; 7 normals: no errors of classification). Fifty six out of the 88 patients (65%) were classified in the 5% risk group after myocardial scintigraphy (42 patients with coronary artery disease with 41 abnormal coronary angiographies and 14 normal patients, all of whom had normal coronary angiographies; this represents a 1.8% divergence of classification compared with coronary angiography). Angioscintigraphy only classified 3 of the remaining patients, one wrongly, and did not seem to be useful diagnostically as a third-line investigation after Thallium scintigraphy or as a second-line investigation instead of Thallium scintigraphy. This strategy is less costly than carrying out coronary angiography systematically in these patients: if diagnostic coronary angiography is performed alone in patients with a risk of 6 to 94% the cost is 4 800 FF vs 10 400 FF per patient; if coronary angiography is performed in all patients in whom coronary artery disease is possible or certain (all patients with a risk of over 5%), the cost is 8 400 FF vs 10 400 FF per patient, a saving of 20%.(ABSTRACT TRUNCATED AT 400 WORDS)
The aim of this study was to compare the diagnostic value of exercise stress testing, Thallium 201 myocardial scintigraphy or after administration of dipyridamole and left ventricular angioscintigraphy performed either during a static (handgrip) or dynamic exercise (bicycle ergometry) for the positive diagnosis of stenosing coronary artery disease. The exercise angioscintigraphy was performed at equilibrium with 99m Tc red blood cell labelling. The global ejection fraction and that of seven radial segments of the left ventricle were measured, the data being recorded within a period of 2 minutes. The handgrip consisted in compressing a dynamometric ball at 1/3 maximal force for 3 minutes, with both hands; the ergometric exercise was increased by 30 Watt 2 minute increments until a positive ECG or 85% of the theoretical maximal heart rate for age was obtained. Normal subjects (n = 29) increased their global (+ 8%) and regional ejection fractions in each of the seven segments (p less than 0.05) during ergometric exercise: there was no significant change of global (-3% NS) or segmental ejection fractions during the handgrip exercise. In the coronary group (at least one greater than 70% stenosis) (n = 61) the fall in global ejection fraction was the same (-14%) with both forms of exercise; a similar fall in the segmental ejection fraction in the territory distal to the stenosis was observed with the handgrip (-22%) and bicycle ergometry (-28% NS). Dynamic exercise testing seemed superior to handgrip exercise. Therefore, the finding of an abnormal global ejection fraction on exercise (i.e. either a global ejection fraction less than the lower limit of normal on exercise, or lower than the global ejection fraction at rest), or of an abnormal regional ejection fraction (i.e. either a regional ejection fraction less than the lower limit of normal over at least 3 segments, or a regional ejection fraction on exercise lower than the regional ejection fraction at rest over at least 3 segments) detected coronary artery disease with a sensitivity of 94% and a specificity of 72%. Dynamic exercise angiography seemed to be more sensitive than maximal ECG stress testing (94% compared to 64%) more rapidly positive (p less than 0.05), as sensitive (94% compared to 83% NS) than Thallium myocardial scintigraphy, but less specific (72% compared to 90%, p less than 0.05), and as unspecific as ECG stress testing.(ABSTRACT TRUNCATED AT 400 WORDS)
The right ventricular ejection fraction is rarely measured, as conventional diagnostic methods (radiology, echocardiography) are confronted with the problem of representing the right ventricle as a simple tridimensional geometrical model. This is not necessary with the radio-isotopic techniques. However, all those used for the measurement of right ventricular ejection fraction lead to important methodological problems. We have therefore developed a technique of measuring this parameter with an infusion of 81 m Kr. This radioactive gas is pure gamma-ray emitter with a 13 second period. Dissolved and infused intravenously, it is eliminated during the first passage through the lung. The continuous separation of the generator of 81 m Kr is performed with isotonic dextrose solution which is then infused for a period of 7 minutes. During this time, the activity detected by the scintillation camera inclined in the 30 degrees RAO projection is stored, together with the electrocardiogram in a computer. The precordial radioactivity of the retrocardiac lung tissue is subtracted after injection of 74 MBq of 99 mTc microspheres. A graph of right ventricular activity can then be reconstructed and the right ventricular ejection fraction calculated. The left ventricular ejection fraction is then measured with 99 mTc--labelled RBCs. This method allows the right ventricular ejection fraction to be measured in the RAO projection, the best incidence for the separation of the right atrial from the right ventricular activity without interference from left ventricular activity because of the pulmonary elimination of the Krypton radioactivity. The measurement performed on a large number of cardiac cycles allows a continuous study of the right ventricular ejection fraction. At the end of the infusion there is no circulating radioactivity so that the measurement can be repeated. This technique was used in 17 patients with acute myocardial infarction. In the 7 patients with anterior infarcts reduction of the left ventricular ejection fraction was the predominant finding (21,6 +/- 6,8%). The right ventricular ejection fraction was 34,2 +/- 6,4%. On the other hand, patients with a postero-inferior infarction had little change in left ventricular ejection fraction (59,2 +/- 12%) but those with right ventricular extension of their infarcts had very reduced right ventricular ejection fractions (less than 23%). The measurement of right ventricular ejection fraction with 81 m Kr is a reliable atraumatic method for diagnosing right ventricular infarction by the quantification of its functional impairment.
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One hundred and five scintiscans of the mammary lymphatic system were performed in 100 patients with breast cancer by intratumoral injection of 99 m Tc-labelled colloidal rhenium. The progression of the radioactive colloidal agent was followed on a series of films taken 1, 2 and 4 hours after the injection, and the images obtained were compared with post-operative findings of lymph node involvement. Patients with more than 3 carcinomatous lymph nodes had less than 2 foci of activity, while those with less than 3 carcinomatous lymph nodes had more than 2 foci of activity, owing to more rapid progression of the compound. The difference was highly significant (p less than 0,001).
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154 patients investigated for chest pain underwent 12 lead exercise electrocardiography and also exercise 201-Thallium myocardial scintigraphy performed at coronary angiography. 92 patients had typical angina; in this group the sensitivity and specificity of exercise electrocardiography was good (91% and 86% respectively) and exercise myocardial scintigraphy did not give significantly better results. On the other hand, in cases when exercise electrocardiography was negative (27%) exercise myocardial scintigraphy was positive in 75%. 201-Thallium did not discriminate between ischaemia and necrosis in patients with previous myocardial infarction, ischaemia alone causing hypofixation on basal myocardial scintigraphy. 62 patients had atypical chest pain. The low incidence of coronary artery disease in this group (30%) increases the value of exercise 201-Thallium scintigraphy as it is both more sensitive (59% compared to 21%, p less than 0,05) and more specific than exercise electrocardiography (43% compared to 85%, p less than 0,1). 29% monotruncular lesions had negative exercise electrocardiography and myocardial scintigraphy. However, multivessel and left main coronary disease may be excluded with great probability by a negative exercise 201-Thallium scintigraphy.
A comparative study of the diagnosis of intracardiac left-to-right shunts by isotope radiography on the one hand and oxymetry, abnormal catheter trajectory and angiocardiography on the other, was performed on a series of 110 patients, comprising 12 normals, 46 valvulopathies or cardiomyopathies without shunts, 23 ASDs, 22 VSDs, and 7 other shunts. Intravenous injection of Technetium 99 m with scintigraphic imagery and interpretation of time-activity curves detected even small left-to-right shunts and appeared to be more sensitive than oxumetry. The estimation of the size of the shunt correlated well with oxymetry for VSDs but not for ASDs. The localisation of the shunt was more difficult. The atrial level of the defect was detected in some but not the majority of cases. The isotopic technique appeared unreliable in the presence of severe haemodynamic disturbances. The isotopic method is a quick means of detecting left-to-right shunts without measurable risk, particularly useful in the investigation of children and young adults thought to have left-to-right shunts.
Rheoplethysmography with occlusion (RPO) is useful in the diagnosis of deep venous thrombosis. Bilateral phlebography with cavography performed afterwards as an emergency gives information as to the embolic potential of the thrombosis and orientates treatment towards surgical interruption of the inferior vena cava. In the C.H.U. at Grenoble 83 clips, 25 umbrella filters and 2 ligatures were placed on the inferior vena cava from 1974 to 1977. Prevention of pulmonary emboli was achieved in 99% cases with lower limb embolic foci. Follow-up by RPO and isotopic phlebography showed that the course of venous thrombosis of the lower limbs seemed to be unchanged by partial interruption of the inferior vena cava, provided that elastic stockings and adequate anticoagulant therapy adapted to venous haemodynamics are used.
The authors report their experience of isotopic angiography as means of post-operative control in peripheral vascular surgery in 200 cases. This investigation is very simple and non-traumatic. It gives very satisfactory morphological information and a good idea of the hemodynamics of the acts carried out.
Natural history of pulmonary embolism observed during a 4-year period in a non-discriminayory Department of Internal Medicine, with reference to 7,843 admissions : 2 per cent of patients, 9 per cent of deaths, 22 per cent of post-mortem examinations. Value of various paraclinical examinations, more especially ECG, lung scintigraphy and determination of blood gases.