Biomedical subjects

D Fagret

Publications and source records attributed to D Fagret.

At least 37 records · Page 2Linked to original sources

PubMed1997

Biological evaluation of two anomeric glucose analogues iodinated in position 6.

Two anomeric analogues of glucose labelled with 123 iodine in position 6, proposed as tracers of glucose transport in vivo, have been synthesized: alpha- and beta-methyl-6-deoxy-6-iodo-D-glucopyranoside (alpha MDIG and beta MDIG). The aim of this study was to determine whether these molecules interact with the glucose transporter and whether they could be used as tracers of glucose transport in vivo. The biodistribution of alpha MDIG and beta MDIG was studied in the mouse in vivo. To determine if these two anomers enter the cell via the glucose transporter, their uptake was measured in isolated perfused rat hearts, in human erythrocytes in suspension, and in cardiomyocytes of neonatal rat in culture. Both alpha MDIG and beta MDIG had similar repartitions in the mouse: myocardial uptake averaged 7% of the injected dose/g of organ at 2 min postinjection and alpha MDIG competed with D-glucose to enter the cells. Insulin produced a 123% increase of its uptake in isolated perfused rat hearts and a 100% increase in cardiomyocytes of neonatal rat in culture. alpha MDIG uptake was lowered in the presence of glucose transport inhibitors in each experimental model. An interaction between beta MDIG and glucose transporters was observed only in human erythrocytes in suspension. Only alpha MDIG interacts with the glucose transporter, and thus could be used to estimate glucose transport in vivo.

Animals↗

PubMed1997

[123I]-6-deoxy-6-iodo-D-glucose (6DIG): a potential tracer of glucose transport.

A glucose analogue labelled with iodine-123 in position 6 has been synthesized: [123I]-6-deoxy-6-iodo-D-glucose (6DIG). The aim of this study was to examine its biological behaviour in order to assess whether it could be used to evaluate glucose transport with SPECT. To establish whether 6DIG enters the cells using the glucose transporter, four biological models have been used: human erythrocytes in suspension, neonatal rat cardiomyocytes in culture, isolated perfused rat hearts, and biodistribution in mice. 6DIG competed with D-glucose to enter the cells and its entry was increased by insulin and inhibited in the presence of cytochalasin B. The biological behaviour of 6DIG was similar to that of 3-O-methyl-D-glucose. 6DIG is a tracer of glucose transport which is very promising for clinical studies.

Animals↗

PubMed1996

Additive value of thallium single-photon emission computed tomography myocardial imaging for prediction of perioperative events in clinically selected high cardiac risk patients having abdominal aortic surgery.

The present study was designed to prospectively evaluate whether reinjection thallium-201 single-photon emission computed tomography (SPECT) has a significant additive predictive value for occurrence of perioperative cardiac events in clinically selected patients at high cardiac risk undergoing abdominal aortic surgery. Of a group of 517 consecutive patients referred, 134 had > or = 2 of the following clinical or electrocardiographic cardiac risk variables: age > 70 years; history of myocardial infarction, angina, or congestive heart failure; diabetes mellitus; hypertension with severe left ventricular hypertrophy; and Q waves or ischemic ST-segment abnormalities on electrocardiogram at rest. Operation was performed after thallium SPECT study. Twelve patients (9%) had major perioperative events (cardiac death or nonfatal myocardial infarction) and 18 patients had other cardiac events (unstable angina, congestive heart failure, or severe ventricular tachyarrhythmia). Variables correlated with the occurrence of major events were history of myocardial infarction (p < 0.05) and the presence (p < 0.001) and number of segments with thallium reversible defects (p < 0.001). In multivariate analysis, history of myocardial infarction (p < 0.05) and the number of segments with reversible thallium defects (p < 0.001) were independent predictors. When all the cardiac events were taken into consideration, all the previous variables, as well as Q waves and ischemic ST abnormalities on the electrocardiogram, showed significant predictive value in both univariate and multivariate analyses. Furthermore, thallium SPECT imaging has an additive predictive value for major cardiac events over clinical and electrocardiographic risk factors. When performed on clinically selected patients at high cardiac risk undergoing abdominal aortic surgery, thallium SPECT demonstrates significant prognostic value for cardiac events over that provided by clinical variables alone.

Aged↗

PubMed1996

Interaction of metaiodobenzylguanidine with cardioactive drugs: an in vitro study.

Metaiodobenzylguanidine (MIBG), an analogue of noradrenaline, is used to explore the functional integrity of sympathetic nerve endings in the human heart. Various drugs inhibit noradrenaline transport systems and may block the uptake of MIBG. As in vivo studies of the effect of these drugs on myocardial [123I]MIBG uptake are often difficult to perform, we used an in vitro human blood platelet model for this purpose. A platelet preparation from healthy volunteers was incubated with [125I]MIBG alone or different concentrations of drugs currently used in cardiology. Labetalol and propranolol inhibited [125I]MIBG uptake, whereas all other drugs tested (other beta-blockers, calcium inhibitors, digoxin and amiodarone) had no effect even at doses exceeding 50 microM. The labetalol dose inhibiting 50% of [125I]MIBG uptake was lower than the plasma concentration of this drug in treated patients, whereas the propranolol dose was higher. This in vitro study of the effect of drugs on MIBG uptake by human blood platelets is predictive of their in vivo effect on myocardial uptake of [123I]MIBG in treated patients, provided that plasma concentration is taken into account.

3-Iodobenzylguanidine↗

PubMed1995

Thallium-201 rest-reinjection and iodine-123-MIHA imaging of myocardial infarction: analysis of defect reversibility.

UNLABELLED: Rest SPECT imaging with [123I]-16-iodo-3-methylhexadecanoic acid (MIHA) frequently shows an increased level of uptake in areas with irreversible defects on exercise 201TI SPECT. Such mismatch patterns between flow (201TI) and metabolic (MIHA) tracers might correspond to areas with ischemic but viable myocardium misidentified by 201TI imaging. METHODS: Eighty-three patients with myocardial infarction underwent exercise SPECT 201TI with rest-reinjection and rest SPECT with MIHA. Defect areas on the exercise images were reversible on MIHA but not on 201TI reinjection images that were determined visually. The presence and extent of these areas were quantified from normalized uptake values for both tracers. RESULTS: In areas with irreversible 201TI reinjection defects, MIHA detected exercise defect reversibility in 59% of patients. In areas with irreversible 201TI reinjection defects, the extent of visually determined defect reversibility on MIHA scans was related to the quantified extent of areas with 201TI uptake > or = 50% of normal; the correlation, however, was weak. In 86% of patients, areas with > or = 50% 201TI uptake were larger than those that were reversible on MIHA. CONCLUSION: After myocardial infarction, rest SPECT with MIHA often enables visual detection of increased uptake in areas with irreversible 201TI reinjection defects.

Exercise Test↗

PubMed1995

Myocardial kinetics of TcN-NOET: a neutral lipophilic complex tracer of regional myocardial blood flow.

UNLABELLED: [Bis (N-etoxy, N ethyl dithiocarbamato) nitrido] 99mTc (V) (TcN-NOET) is a new neutral lipophilic myocardial imaging agent proposed for clinical use for detecting coronary artery disease. We studied the relation between myocardial retention of TcN-NOET and myocardial blood flow (MBF) in a canine model. METHODS: A wide range of MBF was induced by partial regional coronary occlusion and dipyridamole infusion (protocols 1,2 and 3). Myocardial activity of TcN-NOET was determined by in vitro tissue counting at 15 or 90 min postinjection. Tracer activity was correlated with radiolabeled microspheres using linear regression analysis. RESULTS: There was a linear correlation between myocardial TcN-NOET activity and microspheres in protocol 1 (r = 094, 15 min postinjection, protocol 2 (r = 0.94, 15 min postinjection after dipyridamole) and protocol 3 (r = 0.91, 90 min postinjection after dipyridamole). When arterial occlusion was discontinued (protocol 4), there was no longer a close linear correlation (r = 0.26). The first-pass myocardial extraction action of TcN-NOET was 75.5% +/- 4% under basal conditions and 85% +/- 2% under hyperemic conditions (p < 0.01). CONCLUSION: Up to 90 min after injection, the relationship between TcN-NOET myocardial retention and blood flow is excellent over a wide range of flows. After reflow, TcN-NOET redistributes almost completely within 90 min.

Animals↗

PubMed1995

Myocardial perfusion imaging with technetium-99m-Tc NOET: comparison with thallium-201 and coronary angiography.

UNLABELLED: We compared TcN-NOET [bis(N-ethoxy, N-ethyl dithiocarbamato)nitrido 99mTc] and 201Tl images to estimate the utility of this compound in the detection of coronary artery disease (CAD). METHODS: Twenty-five patients undergoing cardiac catheterization had stress-redistribution-reinjection 201Tl SPECT imaging, stress-delayed (2, 4 and 6 hr postinjection) and rest-delayed (4 hr postinjection) TcN-NOET SPECT imaging. RESULTS: Nineteen patients had coronary stenosis > or = 50% and six were normal. Stress TcN-NOET and 201Tl imaging were concordant for the presence of CAD in 22/25 patients (88%, kappa = 0.76 +/- 0.20). The overall sensitivity of TcN-NOET SPECT imaging was 74% (14/19 patients) and 68% (13/19 patients) for 201Tl SPECT imaging. The specificity was 100% (6/6 patients) for both techniques. The overall agreement of TcN-NOET and 201Tl for the presence of disease in individual coronary arteries was 96% (72/75 arteries, kappa = 0.92 +/- 0.16). Segmental analysis of stress images showed a concordance in 211/225 segments (94%, kappa = 0.82 +/- 0.09). Comparison of the 4-hr images showed a concordance between 201Tl and TcN-NOET in 21/23 patients. Following TcN-NOET injection at rest, seven patients had a defect on the initial images, which had normalized 4 hr postinjection in four patients (57%). CONCLUSION: Perfusion imaging with TcN-NOET and 201Tl gives comparable diagnostic information in patients undergoing exercise testing for assessment of CAD. Because of the normalization of myocardial activity 4 hr after injection in some patients, we conclude that TcN-NOET is a potential technetium compound equivalent to 201Tl.

Adult↗

PubMed1994

Prognostic value of thallium-201 single-photon emission computed tomographic myocardial perfusion imaging according to extent of myocardial defect. Study in 1,926 patients with follow-up at 33 months.

OBJECTIVES: This study was designed to assess the prognostic value of thallium-201 single-photon emission computed tomographic (thallium SPECT) perfusion imaging in patients evaluated for stable angina pectoris and to examine the relation, if any, between the presence and extent of myocardial defect and future fatal or nonfatal cardiovascular events (revascularization, secondary myocardial infarction). BACKGROUND: Compared with planar scintigraphy, thallium SPECT enables better evaluation of the extent of myocardial perfusion defect. However, its prognostic value has not yet been studied in a large population of patients. METHODS: Between 1987 and 1989 we studied 3,193 patients. After exclusion of patients with unstable angina, myocardial infarction during the previous month or earlier revascularization, 1,926 patients were followed up for 33 +/- 10 (mean +/- SD) months after stress thallium SPECT imaging (performed after exercise in 1,121 patients or during dipyridamole infusion in 805 patients). Thallium SPECT imaging of the left ventricle was divided into six segments. RESULTS: After normal thallium SPECT imaging (715 patients), the annual total and cardiovascular mortality rates were, respectively, 0.42%/year and 0.10%/year and were significantly higher after abnormal thallium SPECT imaging (respectively, 2.1%, relative risk 5, p = 0.012; 1.5%, relative risk 15, p < 0.0001 [log-rank test]). There was a significant relation between the number of abnormal segments and cardiovascular mortality during follow-up (p < 0.02) or the occurrence of nonfatal events (p < 0.001). The extent of defect on the initial scan provided the best SPECT variable for long-term prognosis. Thallium SPECT imaging provided additive prognostic information compared with other clinical variables (gender, previous myocardial infarction) and exercise electrocardiogram. CONCLUSIONS: In patients with stable angina, normal thallium SPECT imaging indicates a low risk patient, and the extent of myocardial defect is an important prognostic predictive factor.

Adult↗

PubMed1994

Circadian changes of left ventricular ejection fraction in normal subjects.

Sleep has a specific physiology with related cardiovascular changes. We have previously found in respiratory patients [chronic obstructive pulmonary disease (COPD) and sleep apnea syndrome (OSAS)] an unexpected decrease in left ventricular ejection fraction (LVEF) at waking in the morning when compared with the rest period during the day. Whether this observation was linked to the consequences of the respiratory abnormalities or reflected physiological fluctuations related to the changes in autonomic nervous system tone remained unknown. Thus, we have set out to analyze the changes in LVEF with sleep in normal individuals. Eight healthy young men had LVEF measured before and after submaximal exercise, at rest before bedtime, and on waking in the morning. Technetium-99m with in vivo red cell labelling was used. Sleep parameters were assessed using classical polysomnography. In order to detect any influence of autonomic nervous system stimulation on LVEF, sympathovagal tone (SVT) was also assessed during night-time LVEF measurements using spectral analysis of RR intervals. LVEF at rest was within the normal limits for all the subjects (range 51-62%). On submaximal exercise, the LVEF increased in four subjects, was unchanged in two, and decreased in two. The main result concerns the changes in LVEF overnight. In the morning, LVEF decreased dramatically in three subjects and reached a level of < 30% in four. These decreases in LVEF were not related to changes in SVT or sleep structure. LVEF values returned to normal in 30 min. The LVEF changes during exercise are in accordance with previous data in the literature. The dramatic decrease in LVEF observed in the morning could be related either to vascular resistance changes or to nocturnal variations in cardiac contractility, which both need further studies to be established.

Adult↗

PubMed1994

Regional uptake of [123I]-16-iodo3-R,S-methyl hexadecanoic acid in patients with myocardial infarction. Comparison with thallium 201 uptake and wall motion.

Thirty patients with recent myocardial infarction were intravenously injected with the modified fatty acid [123I]16-iodo-3R,S-methyl hexadecanoic acid (MIHA) at peak exercise to quantify viable myocardium after infarction. The results were analysed visually and quantitatively and compared with those obtained after injection of thallium 201 at peak exercise with single-photon emission computed tomography (SPECT) imaging immediately and 4 hours later. Ventriculography was used to study regional wall motion in all patients. In the visual comparison of 201Tl- and MIHA-SPECT scintigrams, 98.8% of normal segments (N) and 96% of temporary thallium-defect segments (T) were N or T on MIHA-SPECT scintigrams (91.3% and 70.5%, respectively, in the quantitative analyses). In contrast, 47.2% of permanent thallium-defect segments (P) were N or T on the MIHA-SPECT scintigrams (20.6% in the quantitative analysis). Revascularization therapy could only be recommended on the basis of MIHA-SPECTs in 5 to 8 of the 30 patients. To confirm the superiority of MIHA over 201Tl to evaluate myocardial viability, one must compare their uptake with myocardial contractility after revascularization.

Exercise Test↗

PubMed1994

Bis(dithiocarbamato) nitrido technetium-99m radiopharmaceuticals: a class of neutral myocardial imaging agents.

UNLABELLED: The synthesis and biodistribution in various animal models (rat, dog, pig and monkey) of 99mTc radiopharmaceuticals containing the Tc = N multiple bond are reported. METHODS: The complexes are represented by the general formula 99mTcN(L)2, where L is the monoanionic form of a dithiocarbamate ligand of the type [R1(R2)-N-C(=S)S]-, and R1 and R2 are variable, lateral groups. The preparations were carried out, both as a liquid and freeze-dried formulation, through a simple procedure involving the initial reaction of [99mTcO4]- with S-methyl N-methyl dithiocarbazate [H2NN(CH3)C(=S)SCH3], in the presence of tertiary phosphines or Sn2+ ion as reductants, followed by the addition of the sodium salt of the ligand (NaL) to afford the final product. The chemical identity of the resulting complexes was determined by comparing their chromatographic properties with those of the corresponding 99Tc analogs characterized by spectroscopic and x-ray crystallographic methods. The complexes are neutral and possess a distorted, square pyramidal geometry. RESULTS: No decomposition of the complexes, in physiological solution, was observed over a period of 6 hr. Imaging and biodistribution studies demonstrated that these radiopharmaceuticals localize selectively in the myocardium of rats, dogs and primates, but that they failed to visualize the pig heart. The kinetics of heart uptake and clearance were studied in rats and dogs, and found to be strongly influenced by variation of the lateral R1 and R2 groups. CONCLUSION: The high quality of myocardial images obtained in dogs and monkeys demonstrates that the derivative 99mTcN[E-t(EtO)NCS2]2 [99mTcN(NOEt)] exhibits the most favorable distribution properties for further studies in humans.

Animals↗

PubMed1993

[Evaluation of prognosis and myocardial ischemia using thallium in myocardial tomoscintigraphy].

Thallium scintigraphy holds a unique position amongst the methods available for evaluating the prognosis of coronary patients: it enables quantification of underperfused myocardium and evaluates already constituted ventricular damage (irreversible necrosis) and areas at risk of future coronary events (viable but ischemic myocardium). In a series of 1,926 patients who underwent exercise stress or dipyridamole Thallium myocardial scintigraphy for angina pectoris and followed up fort an average of 34 months, the following features were observed: the long-term prognosis in patients with normal myocardial scintigraphy (715 patients) was identical to that of a normal population of the same age (0.11% cardiovascular deaths per year) whereas the cardiovascular mortality was 15 times higher in cases with a pathological scintigraphy: finally, the long-term prognosis (cardiovascular deaths, infarcts or secondary revascularisation) was directly related to the severity of the initial lack of Thallium uptake. This method was used to assess the prognosis and evaluate the myocardial ischaemia in 75 patients who underwent complete surgical revascularisation fort ischaemia, 50 of whom had previous myocardial infarction: all patients had at least one arterial bypass graft: 39% of the myocardium was underperfused before revascularisation; this procedure reduced by 80% (p < 0.0001) the zones of reversible underperfusion but also zones of irreversible underperfusion by 17% (p = 0.04). The results were particularly impressive in patients who underwent revascularisation with an arterial pedicle (left and right internal mammary, gastroepiploic alone or in association) as 91% of the ischemic territories recovered on average 13 days after revascularisation.(ABSTRACT TRUNCATED AT 250 WORDS)

Dipyridamole↗

PubMed1993

Myocardial uptake of metaiodobenzylguanidine in patients with left ventricular hypertrophy secondary to valvular aortic stenosis.

UNLABELLED: The time course of myocardial uptake of metaiodobenzylguanidine ([123I]MIBG) was studied in 26 patients: seven control subjects (Group 1) and 13 patients with left ventricular hypertrophy secondary to valvular aortic stenosis. Seven of these had received no treatment (Group 2) and six were receiving amiodarone or digoxin (Group 3); six heart transplant recipients were investigated for extra neuronal myocardial uptake of [123I]MIBG (Group 4). The index of myocardial [123I]MIBG uptake was lower in Groups 2 and 3 than in Group 1 (Group 2: 1.42 +/- 0.07, p < 0.001; Group 3: amiodarone, 1.30 +/- 0.10, p < 0.05; digoxin, 1.22 +/- 0.06, p < 0.01; Group I: 1.83 +/- 0.18) and lower in Group 3 than in Group 2. Patients of Group 4 showed a much lower mean index of myocardial [123I]MIBG uptake than the control group (1.07 +/- 0.08, p < 0.001). IN CONCLUSION: 1. Patients with left ventricular hypertrophy secondary to valvular aortic stenosis were found to have lower myocardial [123I]MIBG activity and rapid washout than the control subjects. 2. Amiodarone and digoxin partially inhibited myocardial [123I] MIBG uptake. 3. Extra neuronal myocardial uptake of [123I]MIBG in humans only accounts for 13% of the total cardiac activity.

3-Iodobenzylguanidine↗

PubMed1992

[Value of new isotopes in cardiology].

Nuclear Cardiology has seen many advances in the past few years: new indications for tracers already known, but also the appearance of new markers, by single photon imaging or by position emission (PET). With regard to the investigation of myocardial perfusion, thallium remains the most widely used isotope. Its sensitivity in the diagnosis of coronary disease is improved by the use of scintigraphic CT scan (SPECT) and excellent predictive value in terms of the onset of coronary events or mortality has been confirmed in particular. At the same time, the sensitivity and specificity of new technetium markers have been better defined. The investigation of myocardial metabolism, accessible up to now only via PET and confined, in France, to the domain of clinical research, is in the process of becoming a tool suitable for use by clinicians as a result of new SPECT-Thallium protocols (reinjection, late redistribution and rest), but also because of the development of single photon markers of myocardial viability, e.g. iodinated fatty acids. A functional approach to coronary disease, indispensable adjuvant to the anatomical approach, is now possible on a routine basis.

Heart Diseases↗

PubMed1992

[Study of new thrombolytic agents in myocardial infarction: a multicenter randomized trial (APSAC versus rt-PA)].

A hundred and eighty three patients with a primary myocardial infarction less than 4 hours old were included in a double blind trial versus placebo comparing an isolated plasminogen streptokinase activator complex (APSAC: 30 mu in 5 mn) and tissue type plasminogen activator (rt PA: 10 mg bolus followed by 90 mg in 130 mn). Clinical evolution, side effects, patency of the artery responsible for infarction, left ventricular contractile function (contrast angiography on the 7th day and angioscintigraphy on the 21st day) and infarct size were studied. The two groups were comparable in age (54 +/- 11 years), delay in randomisation (170 +/- 50 mn), infarct site and severity of cardiac failure. There was no significant difference in hospital mortality (7 in the rt PA group and 5 in the APSAC group) or in adverse effects (haemorrhage: rt PA: 9 patients, APSAC: 11 patients). The patency was 72% in the APSAC and 76% in the rt PA group. Left ventricular function and infarct size were comparable in the two groups: angiographic EF (0.50 +/- 0.1 in the APSAC and 0.52 +/- 0.1 in the rt PA group: NS); asynergic score (11.3 +/- 1.7 in the APSAC and 10.5 +/- 1.8 in the rt PA group: NS); infarct size (10.9 +/- 8.0 in the APSAC and 9.4 +/- 7.2 in the rt PA group: NS). This trial shows that these two thrombolytic agents have the same efficacy. The authors recommend adaptation of the dosage of rt PA to body weight.

Adult↗

PubMed1992

[Evaluation of norepinephrine content in the myocardium in hypertensive patients with left ventricular hypertrophy].

The sympathetic nervous system seems to be a non hemodynamic factor involved in the development of hypertension and in left ventricular hypertrophy determinism. The aim of this study was to estimate the myocardial norepinephrine content in essential hypertensive patients, using a reliable radio-iodinated marker of norepinephrine: the 123I-meta-iodobenzylguanidine (123I-meta-iodobenzylguanidine). Eight male and female hypertensive patients with left ventricular hypertrophy and average age of 52 +/- 9 years underwent a resting, ambulatory and effort blood pressure measure. Echocardiographic parameters allowed measure of left ventricular mass index (according to Devereux, and we considered left ventricular hypertrophy as left ventricular mass index greater than 120g/m2. Plasma norepinephrine is measured at rest. Cardiac and mediastinal radioactivity is detected 4 h after a 4mCi i.v. injection of 123I-meta-iodobenzylguanidine and meta-iodobenzylguanidine myocardial uptake is definite as the cardiac/mediastinal ratio (N:1.78 +/- 0.19). Meta-iodobenzylguanidine-myocardial uptake average value of hypertensive patients was 1.89 +/- 0.19 (1.63 to 2.25) without statistical difference to control subjects. We found a significative correlation between meta-iodobenzylguanidine myocardial uptake and effort systolic blood pressure variation in one hand, and with heart rate increase with effort in the other hand. There is no correlation between meta-iodobenzylguanidine-myocardial uptake and left ventricular mass index or ambulatory blood pressure. In hypertensive patients with left ventricular hypertrophy, meta-iodobenzylguanidine myocardial uptake is normal or high, in agreement with experimental data in SHRs, model of human essential hypertension. Therefore myocardial scintigraphy with 123I-meta-iodobenzylguanidine can appreciate cardiac norepinephrine content in humans.

3-Iodobenzylguanidine↗

PubMed1992

[Action of labetalol on norepinephrine myocardial content in left ventricular hypertrophy in hypertensive patients].

The high incidence of cardiovascular morbidity and mortality in hypertensive patients with left ventricular hypertrophy shows the great interest in understanding the pathophysiology of this process. Many reports suggest the role of catecholamines in generating left ventricular hypertrophy. The aim of this study is to evaluate the effect of labetalol on myocardial norepinephrine content in hypertensive subjects with left ventricular hypertrophy by using an isotopic norepinephrine marker, the 123I-meta-iodobenzylguanidine (123I-MIBG). Eight male and female hypertensive patients with left ventricular hypertrophy were investigated after a 30 day placebo period. Resting, ambulatory and effort blood pressure was measured. Echocardiographic parameters allowed measure of left ventricular mass index according to Devereux. And we considered left ventricular hypertrophy as left ventricular mass index greater than 120 g/m2. Cardiac and mediastinal radioactivity is detected 4 h after a 4 mCi i.v. injection of 123I-MIBG and MIBG myocardial uptake is definite as the cardiac/mediastinal ratio (N : 1.78 +/- 0.19). All subjects received at the beginning of the study (D0) 2 tablets of labetalol 200 mg, increased to 4 tablets if diastolic blood pressure during follow-up remained above 95 mmHg. Patients again underwent these explorations after 3 months of treatment (D90). Labetalol decreases in considerable manner MIBG myocardial uptake as it has been shown that it decreases tissular norepinephrine content in experimental studies. Therefore, MIBG myocardial uptake seems to be a reliable tool in evaluating drugs effect on cardiac sympathetic nervous system.

3-Iodobenzylguanidine↗

PubMed1992

[Clinical evaluation after myocardial infarction. Its role, date and methods].

Although global mortality in the year following myocardial infarction is about 10%, this figure varies from less than 1% to more than 50% in some very high risk cases. The principal objective of clinical evaluation during the acute phase is to establish a prognosis and propose a rational strategy for myocardial revascularisation (by bypass grafting or angioplasty) in patients with a poor prognosis. An essential feature of this evaluation is to reduce health care costs and hospital stay to a minimum. Coronary angiography is the only investigation which allows assessment of the coronary circulation and is probably the best method of evaluating global and regional left ventricular function, two essential prognostic factors: on the other hand, it does not provide information about the presence of residual ischaemia or persistent myocardial viability in the infarcted territory. Some very high risk patients should undergo systematic coronary angiography to determine the possibilities for myocardial revascularisation: early post-infarction angina, left ventricular failure, chronic angina, elderly but valid patients... The indications of coronary angiography should also extend to patients with non-Q wave infarction, to young patients with myocardial infarction on thrombolysed infarcts: results of coronary angiography should then be compared with those of standard exercise stress testing. It is only in other situations, concerning a minority of patients, in which two attitudes may be considered: the first, to perform coronary angiography very early (within 24-48 hours of admission) allowing early discharge from hospital of many cases, completed later by standard exercise stress testing: any revascularisation procedure is considered at that time and requires a second hospital admission. The second attitude consists in performing coronary angiography between the 7th and 10th day only if some paraclinical changes are present: exercise stress testing then has an essential role; to improve its negative predictive value for absence of long-term coronary events it should be associated with radionuclide investigation of myocardial perfusion (thallium, MIBI) or with an evaluation or residual myocardial viability (labelled fatty acids, cyclotron). This attitude also allows early identification of "good candidates" for myocardial revascularisation.

Coronary Angiography↗