Atrial fibrillation and anticoagulation.

Atrial fibrillation (AF) increases the risk of ischemic stroke due to the formation of a thrombus within left atrium. Thus, adjusted-dose (optimal INR: 2-3) anticoagulant therapy such as warfarin dramaticaly decreases this risk of embolic events both in primary and secondary prevention but slightly increases the risk of bleeding, particularly in the elderly. This explains that, although the benefit has been clearly demonstrated, the anticoagulant therapy remains underused. The efficacy of low doses of aspirin is less clear but it may be appropriate in younger patients with lone AF because of a low risk of embolic events. The combination of low doses of warfarin and aspirin should not be given. In case of contraindication to warfarin and aspirin, some others drugs such as indobufen or dipyridamole may be given but the most promising drug is ximelagatran, a direct thrombin inhibitor, which appears to be as effective than warfarin with a lower incidence of bleedings. For patients in AF who require urgent cardioversion, intravenous unfractionated heparin remains the anticoagulant of choice but an approach combining low-molecular-weight heparin and transesophageal echocardiography has been proposed. For each patient the decision of treatment must be tightly correlated to the benefit-risk ratio.

Comparative study of atrial vulnerability in patients with unexplained ischemic stroke or lone atrial paroxysmal fibrillation.

Strokes have a high prevalence, with a high rate of recurrence, and about 30-40% remain of unknown cause. Some patients might have asymptomatic paroxysmal atrial fibrillation (AF) which remains the main cause of embolic events. A latent atrial arrhythmogenic substrate may induce recurrent arrhythmias, including functional abnormalities such as nonuniform refractoriness and/or anatomic abnormalities such as atrial septum aneurysm (ASA) and patent foramen ovale (PFO). In 175 patients divided into three groups (Group I: 103 patients with unexplained ischemic stroke, Group II: 48 patients with paroxysmal AF and Group III or control group: 24 patients explored for another cause), such an atrial arrhythmogenic substrate was assessed by electrophysiological study. Groups I and II had a similar high rate of inducible atrial arrhythmias compared to control group III where no arrhythmia was induced. An induced atrial arrhythmia was observed in more than 50% of patients of Group I and in more than 70% of patients of Group II without any significant difference according to age. However, in 26 young patients of Group I who had a transesophageal echocardiography, both a high rate (46%) of ASA and/or PFO and a frequent latent atrial vulnerability (LAV) were observed, compared to older patients where an atrial septum abnormality was observed in only 21% of cases. Thus, among patients with stroke of unknown cause, a high percentage of them might have asymptomatic atrial paroxysmal arrhythmia. The predictive value of the electrophysiological study for spontaneous arrhythmias and recurrence of stroke remains to be demonstrated.

[Vascular risk and menopause: role of hormone replacement therapy]. / Risque vasculaire de la ménopause: intérêt du traitement hormonal substitutif.

RATIONALE: Menopause dramatically increases cardiovascular risk in women who lack the protecting effects of estrogens. This emphasizes the importance of hormone replacement therapy (HRT) which, until recently, was considered beneficial in spite of the heterogeneous nature of clinical studies. Such a benefit was supposed to result from the favorable effects of estrogens, including lipid lowering and a complex vasodilating action including the improvement of vascular endothelial function. RATIONALE REVISITED: The results of the HERS study have however questioned these affirmations because of the lack of clinical benefit due to HRT in secondary prevention of coronary artery disease in postmenopausal women, with an increased vascular risk during the first year of treatment. In clinical practice, it is not recommended to start HRT after a cardiac attack. PRACTICAL ATTITUDE: In fact, the HERS study used a conjugated equine estrogen and progestin (with possible deleterious effects) and cannot be compared to French prescription habits which are based on the use of natural hormones. However, it remains to be demonstrated that some HRT regimens, in particular those using progesterone, may provide a real benefit in terms of lower cardiovascular morbidity-mortality.

[Comparative study of cibenzoline and flecainide by oral route for preventing recurrence of paroxysmal atrial tachyarrhythmias]. / Etude comparative de la cibenzoline et du flécaïnide administrés par voie orale dans la prévention de récidive des tachyarythmies auriculaires paroxystiques.

Although paroxysmal atrial arrhythmias are the commonest form of arrhythmia, their therapeutic management still remains controversial. Seventy one patients were included in a multicentre, randomized double-blind, double-placebo study, in parallel groups (37 in group C and 34 in group F) to compare the efficacy of cibenzoline (C) and flecainide (F), administered orally, in the prevention of recurrent atrial arrhythmia. The arrhythmia usually consisted of atrial fibrillation (n = 65), while 6 patients presented with paroxysmal atrial flutter. The mean daily dosages were 221 +/- 60 mg (C) and 165 +/- 49 mg (F). The mean age was 63 +/- 12 years in group C and 63 +/- 16 years in group F. In this trial, atrial arrhythmia was idiopathic in almost two-thirds of cases. The duration of follow-up of this study was 6 months, during which recurrences of arrhythmia were evaluated in terms of the symptoms experienced and in terms of ECG and Holter examinations repeated at the 3rd and 6th months. Supplementary ECG and Holter examinations were also performed in the presence of a clinical suspicion of recurrent symptoms. Comparison of the percentages of patients not developing a documented recurrence and who tolerated treatment, by Kaplan-Meler curves, showed a significant difference between cibenzoline (58%) and flecainide (56%). In the not-responders, the mean time to recurrence was 75 +/- 48 days in group C and 75 +/- 62 days in group F(NS). Six patients dropped out of the trial because of adverse events, including 3 cardiac adverse events (2 case of ventricular proarrhythmic activity). Four extracardiac adverse events led to discontinuation of treatment in group C. In conclusion, the efficacy of cibenzoline and flecainlde in the secondary prevention of atrial arrhythmia was found to be comparable, with 58% and 58% of patients in sinus rhythm, respectively, with a follow-up of 6 months.

[Aspirin in secondary cardiovascular prevention: from clinical studies to daily practice]. / L'aspirine en prévention secondaire cardio-vasculaire: des études cliniques à la pratique quotidienne.

The clinical benefit of aspirin in coronary insufficiency has been validated in the acute phase of myocardial infarction and in secondary prevention with a reduction of the risk of recurrent infarction of the order of 30%. By interfering with the process of thrombolysis, aspirin modifies the natural history of coronary artery disease by decreasing the frequency and severity of pathological events. Although a relative consensus has been reached concerning the dosages (160 to 325 mg/day), the use of aspirin nevertheless remains very insufficient, sometimes because of the risk of gastrointestinal intolerance related to the gastrotoxicity of aspirin, hence the importance of pharmaceutical forms designed to improve the gastrointestinal tolerance, such as calcium carbasalate (soluble aspirin complex), which appears to be particularly well tolerated.

[Antiaggregant effect and tolerance of calcium carbasalate administrated immediately after aorto-coronary bypass. Results of a double-blind versus placebo study]. / Efficacité Antiagrégante et tolérance du carbasalate calcique administré dans les suites immédiates des pontages aorto-coronaires. Résultats d'une étude réalisée en double aveugle versus placebo.

The patency of aorto-coronary bypasses is greatly influenced by platelet aggregability, and there is an associated risk of thrombosis which may occur very early during surgery. It is in this context that aspirin has been the subject of successful clinical studies. When administering aspirin, it is preferable to choose formulations that are well tolerated by the gastro-intestinal tract. This was the reason for carrying out the present randomised single-centre double-blind parallel-group study aimed at confirming the platelet anti-aggregant effect and tolerability of calcium carbasalate administered during the immediate postoperative period. The dose prescribed was equivalent to aspirin 325 mg daily, and was given as a single dose 6 hours after the end of the operation and repeated for 7 days, versus placebo, in 56 patients undergoing aorto-coronary bypass grafts. A clinical assessment, ECG, platelet count and measurements of CPK and CPK-MB were carried out daily for the 7 days of the study. Tests of platelet aggregation (to arachidonic acid, ADP and collagen), assays of serum thromboxane B2, MDA and PDF, and urinary assays for beta-thromboglobulin and 6-keto-PGF-1 were carried out before treatment, then 1 and 7 days after the start of treatment. Fifty males (89%) and 6 females, mean age 58.3 years, received treatment with either calcium carbasalate (group C, n = 28) or placebo (group P, n = 28). The atheromatous lesions present in most cases represented triple-vessel disease (37 cases), and most operations were triple bypasses (23 cases) or double bypasses (20 cases). A significant reduction in platelet aggregation to arachidonic acid and collagen on D1 (p = 0.05) and D7 (p < 0.001), and to ADP on D7 (p < 0.01) was observed in group C as compared with group P. Group C also showed significant reductions as compared with group P in respect of serum thromboxane B2 levels on D1 (p < 0.01) and D7 (p < 0.001) and MDA levels on D1 and D7 (p < 0.001). No significant difference was demonstrated between the two groups in respect of urinary 6-keto-PFG-1 excretion. The number of patients showing a rise in CPK was lower in group C but this difference did not reach statistical significance. ST segments change were comparable in the two groups, and no patient complained of anginal pain during the study. These results show that calcium carbasalate administered at a dose equivalent to 325 mg aspirin daily caused very early inhibition of platelet aggregation, specifically inhibiting platelet production of thromboxane B2 without altering prostacyclin levels. In addition, calcium carbasalate was found to be well tolerated. This study confirms the value of early administration of aspirin at a dose of 325 mg daily during the hours immediately following aorto-coronary bypass graft surgery.

[Injectable and oral cibenzoline in the treatment of supraventricular tachycardia related to intranodal reentry or accessory atrioventricular conduction pathway]. / Etude de la cibenzoline injectable et orale dans le traitement des tachycardies supraventriculaires liées à une rentrée intranodale ou à une voie de conduction auriculo-ventriculaire accessoire.

Cibenzoline, a Vaughan-Williams Class I antiarrhythmic agent, was studied in 26 patients with orthodromic supraventricular tachycardia (SVT) by nodal reentry (n = 10) or an accessory pathway (AP) (n = 16). IV cibenzoline accelerated sinus rhythm, prolonged PR, AH, HV and QT, widened QRS and depressed or blocked anterograde and retrograde conduction in the accessory pathway, significantly, without significantly modifying conduction capacity in the AV node, nor atrial, nodal or ventricular refractory periods. It converted 6/10 of nodal reentries and 9/16 of reentries due to an AP, by a mean dose of 1 mg/kg, in 2 to 3 minutes, in 12 cases out of 16 by blocking retrograde conduction in the reentry circuit. It prevented reinduction of 12 of the 26 cases of SVT, significantly slowing the cycle of induced SVT in other patients. Oral cibenzoline (260 to 390 mg/day) prevented induced SVT in 11 cases out of 25 and spontaneous SVT in 14 cases out of 26, with a follow-up of 11 +/- 4 months (6 to 16), and this regardless of the reentry mechanisms. Intravenous cibenzoline was not associated with any clinical or hemodynamic intolerance but there was facilitation of episodes of SVT in one patient. Oral administration caused only one case of digestive intolerance, leading to lowering of the dose. Plasma levels showed no significant differences between successes and failures, for both the injection and oral formulations of cibenzoline, whether in terms of the conversion or prevention of episodes. Electrophysiological investigations had a 60% positive and 50% negative predictive value, a sensitivity of 64% and a specificity of 50%. Cibenzoline thus appears to be useful for the conversion and prevention of episodes, SVT, regardless of the reentry circuit, and seems justified, in view of its good safety/acceptability, as first line treatment in this diagnostic indication, measurement of plasma levels and electrophysiological investigations being of little apparent value in terms of guiding treatment and predicting its results.

[Study of the efficacy and tolerability of oral administration of cibenzoline in the prevention of recurrence of symptomatic atrial fibrillation]. / Etude de l'efficacité et de la tolérance de la cibenzoline administrée par voie orale dans la prévention des récidives de fibrillation auriculaire symptomatique.

The efficacy and safety of oral cibenzoline were evaluated in 42 patients aged 67 +/- 7 (55-80) and with recurrent symptomatic atrial fibrillation for at least a year and for which at least one previous anti-arrhythmic agent had been stopped for inefficacy or intolerance. Cibenzoline was administered for 6 months at the dose of 260 to 390 mg per day in patients aged under 70, with the possibility of reducing this dose in those aged over 70. Clinical, electrocardiographic and 24-hour Holter evaluation took place at inclusion and after 3 and 6 months' treatment or at the time of trial termination for documented recurrence (atrial arrhythmia persisting for 60 seconds or more). The mean duration of atrial fibrillation was 5.6 +/- 5 years (1-26). It was related to ischemic (22%), valvular (17%), hypertensive (17%), hypertrophic (7%) or dilated (7%) heart disease. No etiology was found in 45% of cases. All patients had taken at least one anti-arrhythmic agent in the past (mean of 2 drugs, range 1 to 6). All patients were symptomatic, the commonest symptoms being palpitations (82%), chest pain (28%), feelings of vertigo (11%) or episodes of acute dyspnea (9%). Thirteen patients (31%) had a documented recurrence (> 60 seconds) during the six months of the trial. Recurrence occurred during the first months of treatment in the majority of patients (11 out of 13). The number of symptomatic patients decreased considerably during treatment with cibenzoline, with the disappearance of palpitations in 83% of cases.(ABSTRACT TRUNCATED AT 250 WORDS)

[Angiotensin converting enzyme inhibitors and vascular remodelling in arterial hypertension]. / Inhibiteurs de l'enzyme de conversion et remodelage vasculaire dans l'hypertension artérielle.

The prescription of angiotensin converting enzyme (ACE) inhibitors contributes in everyday practice to the normalisation of blood pressure (BP) in individuals with essential hypertension (HT). Inhibition of the circulating renin angiotensin system (RAS) is accompanied, acutely, by a fall in BP. The effects of ACE inhibitors in the longer term is more complicated, including inhibition of tissue RAS and, finally, an action on the vascular structure itself which is apparently of fundamental importance. ACE inhibitors contribute to improving compliance of major arteries and to decreasing arteriolar resistance while leaving regional blood flow unaffected. There are additional beneficial modes of action such as the reversibility of endothelial dysfunction or inhibition of the cell migrations which are a prelude to atherosclerosis. These effects may be linked to the therapeutic group, but certain ACE inhibitors with particular tissue tropism have a more effective action regarding tissue RAS. This might be associated with a more significant fall in HT-related cardiovascular morbidity.

[Arterial hypertension, vascular remodelling and atherosclerosis]. / Hypertension artérielle, remodelage vasculaire et athérosclérose.

Therapy of essential hypertension (HT) should not imply the simple lowering of blood pressure alone but also reduction of the trophic effects provoked on the vascular system. Regression of left ventricular hypertrophy must be combined with "remodelling" of the overall arterial network to adapt to the abnormal physical forces acting on the vascular wall. This adaptive process has both qualitative and functional effects with structural modifications of the large arterial trunks as well as the smaller arteries, provoking adverse effects once they increase vascular resistance and diminish large artery compliance. Additionally, they tend to induce chronicity of HT, particularly since at the crossroad of these pathologic processes exist anomalies of endothelial secretory function. Treatment of HT should therefore comprise care of the vascular system, inasmuch as common mechanisms of cellular hypertrophy and proliferation are found in uncomplicated hypertension and atherosclerosis.

[Combination of oral administration of cibenzoline and digoxin in patients with supraventricular arrhythmia]. / Association de la cibenzoline et de la digoxine administrées par voie orale chez des patients ayant une arythmie supraventriculaire.

Chronic co-administration of digoxin and several antiarrhythmic drugs increases digoxin plasma levels. To determine the effects of the administration of oral cibenzoline on digoxin plasma levels and its effects on clinical and electrocardiographic parameters, we conducted a prospective multicenter study in 22 cardiac patients with a mean age of 66 +/- 12 years (39-85), who were on long term digoxin therapy (0.25 mg once daily for at least 2 weeks) and who required oral cibenzoline therapy in the prevention of recurrence of symptomatic atrial tachyarrhythmias. Cibenzoline was given for 4 weeks at a dose of 130 mg twice daily in patients aged less than 70 years (group I, n = 15) and this dosage was reduced by half in patients over 70 years of age (group II, n = 7). Evaluation of the effects of this combination on clinical and electrocardiographic tolerability as well as the drawing of blood samples for assay of cibenzoline and digoxin took place before and after 4 weeks treatment with cibenzoline. The digoxin plasma levels were (mean +/- sem) 0.96 +/- 0.1 ng.ml-1 before cibenzoline administration and remained unchanged after 4 weeks of combination therapy (1.0 +/- 0.1 ng.ml-1), p > 0.05. Digoxin plasma levels in group I varied from respectively 0.8 +/- 0.1 ng.ml-1 (0.5-1.7) to 0.8 +/- 0.1 ng.ml-1 (0.4-1.5) and in group II from 1.2 +/- 0.2 ng.ml-1 (0.6-2) to 1.4 +/- 0.3 ng.ml-1 (0.7-2.5). This therapy was well tolerated in 16 patients out of 21 evaluable patients (76%) and there was no significant change in vital signs during the study.(ABSTRACT TRUNCATED AT 250 WORDS)

[Interruption of the infra-renal inferior vena cava with azygos continuation. Case report]. / Interruption infra-rénale de la veine cave inférieure avec continuation azygos. A propos d'un cas.

The authors report a case of congenital interruption of the inferior vena cava with azygos continuation with a deep venous thrombosis of the left lower extremity. It is a rare congenital abnormality which is most of the time asymptomatic. However such an abnormality may be a problem in case of cardiac catheterization or thoracic surgery.

[Quality of life of patients with hypertension treated with converting enzyme inhibitors]. / Qualité de vie des hypertendus traités par inhibiteurs de l'enzyme de conversion.

Converting enzyme inhibitors (CEIs) are widely used in treatment of essential hypertension. Large-scale clinical studies have shown that CEIs are well tolerated and cause fewer side effects than most other antihypertensive agents. The latter observation is fundamental for compliance with long-term treatment. There do exist, however, some side effects which although rare are not negligible. It is necessary though to distinguish between side effects linked to the class of therapeutic agents and those associated with particular structural features. Three types of side effects have been seen: 1) manifestations linked to inhibition of angiotensin II with systemic vasodilation (hypotension, vertigo) and decreased glomerular pressure (functional renal impairment) with preferred onset in renovascular hypertension; 2) potentiation of the bradykinin-prostaglandin system which causes cutaneous eruptions and for reasons still poorly understood a cough which may justify discontinuance of treatment: 3) side effects for which the sulfydryl group is essentially responsible (rash, dysgeusia, neutropenia, proteinuria) and which basically appear to be linked to the use of high doses of captopril. In general terms, and bearing in mind the frequently dose-dependent character of the side effects, it is advisable to prescribe low doses of CEIs, and this therapeutic approach is strengthened by the possibility of concomitant use of a thiazide diuretic allowing improved antihypertensive effects, coupled to better reciprocal tolerance of the drugs. The end result is a better quality of life for the hypertensive subject, and hence improved compliance with long-term treatment.

[Oral contraception and the vascular risk]. / Contracepção oral e risco vascular.

PIP: Vascular risk, mainly thromboembolitic risk, attributed to oral contraceptives (OCs) since 1962, has been primarily linked to ethinyl estradiol (EE). OCs which combine estrogen and have been associated with cerebral vascular accidents. A 1977 study showed a 40% increase of mortality due to cardiovascular complications in women taking OCs. There were of both an arterial and a venous character. The risk of myocardial infarction was 3 times more frequent among OC users. Deep venous thrombosis and pulmonary embolism were more numerous. Some other risk factors include smoking, hypertension, diabetes, and age 35. The risk of heart attack vanishes a few years after stopping OC use. The reduction of EE (and similarly progesterone) dosage from 100-50 mcg also lower the risk of hypertension, cerebral vascular accidents, and venous thrombosis. Prolonged use of OCs causes disorders of hemostasis affecting the walls of blood vessels, modifying the viscosity of blood flow (increase of hematocrits, reduction of venous tonus), modifying plasmatic coagulation (increase of platelets, increase of factors VII and X and plasma fibrinogen, and decrease of antithrombin III activity), and increased fibrinolysis. These anomalies are exclusively associated with high doses of estrogens. 5% of women using OCs develop moderate hypertension of 5-10 mm Hg of systolic pressure 5 years later, but after cessation it is reversed. OCs stimulate the renin-angiotensin-aldosterone system causing accelerated production of angiotensin II with the resultant forceful vasotension. 3 months after quitting OC use, high blood pressure returns to normal. EE can provoke diabetes; it increases very low density lipoprotein (VLDL) and high density lipoprotein (HDL) production, but total cholesterol is hardly affected. The androgenic property of progestogens reduces HDL. Combined OCs are contraindicated for women with hypertension, hyperlipidemia, diabetes, and a family history of vascular accidents.^ieng

[Essential arterial hypertension. From notion to treatment]. / L'hypertension artérielle essentielle. Du concept au traitement.

Arterial hypertension (AH) is an excessive elevation of the arterial blood pressure (ABP) in the systemic circulation. It is, however, arbitrary to define a limit between normal and pathological ABP, since the ABP varies in a continuous fashion with the population. Occasional measurement of the blood pressure by sphygmomanometer is rather inaccurate but still remains the method of reference. A more precise determination of the ABP is possible by using the stress blood pressure profile and ambulatory measurement which are prognostically far superior to occasional measurement. AH is not a disease but a risk factor--quantitative and independent of the cardio-vascular system because it contributes to atherosclerosis and regional ischemic processes. The genesis of the so called essential AH still remains unclear, but it is getting better known: from a genetic factor of predisposition, the respective roles of the salt and the kidney as a filter are determining, along with the more or less appropriate action of hormonal factors of the sodium excretion. This is combined with the complex and synergistic action of potent vasopressor mechanisms such as the sympathetic nervous system and the renin-angiotensin systems--circulating as well as in the tissues. AH presents haemodynamic abnormalities, which vary according to age, and among which the elevation of systemic vascular resistances is most characteristic. This is combined with a lack of compliance of the large arterial vessels, and secondarily, a hypertrophy, partially adaptive, of the entire cardiovascular system. This includes left ventricular hypertrophy which has harmful effects on intracardiac and coronary haemodynamics, resulting in an increased mortality. It is therefore necessary that the treatment, not only decrease the blood pressure, but also take into account the regional vascular outputs while respecting and improving the renal, cerebral and coronary circulations with general improvement of the vascular compliance. The treatment must also result in an early and lasting decrease of the myocardial hypertrophy. This is why the new anti-hypertensive treatments (conversion enzyme inhibitors and calcium inhibitors) represent a desirable therapeutic alternative to the classical treatment. Their prescription follows a few general rules, but must, however, remain very personalized with evaluation of the results at two levels: individual control of the ABP and mass benefit in terms of decreased cardiovascular morbidity and mortality.

[Systemic effects of beta blockaders used in collyria]. / Effets systémiques des bêtabloquants en collyres.

Eye-drops containing beta-blockers are widely used by ophthalmologists in the treatment of chronic glaucoma, since they reduce the intraocular pressure by about 25-30 per cent. This treatment is usually well tolerated but not devoid of systemic effects. The eye-drops are rapidly removed by the lacrymal system, and 80 per cent of the drug is absorbed by the nasal mucosa. It is then taken up by the blood stream in low but not negligible concentrations, and since the liver is by-passed the active substance acts directly on the target organs. Side-effects are similar to those observed after oral administration, despite much lower plasma levels; although rare in routine clinical practice, they may result in decompensation of a fragile cardiac or respiratory function. This does not mean that beta-blocker eye-drops should not be prescribed to patients with chronic glaucoma, but attention must be paid to the patient's cardio-respiratory status and to a possible concomitant treatment with drugs that depress myocardial conductivity or contractility.

[Medical treatment of cardiac insufficiency. Advances and controversies]. / Le traitement médical de l'insuffisance cardiaque. Acquisitions et controverses.

In the treatment of chronic congestive heart failure (CHF), digitalis has empirically proved to be effective in reducing functional signs and symptoms. However, it is among patients treated with digitalis, diuretics and salt-free diet that mortality is still high. Moreover, the use of digitalis derivatives in CHF with sinus rhythm is controverted due to the frequent toxicity of these drugs and to their allegedly weak positive inotropic activity. Current research in this field therefore is oriented towards non-digitalis cardiotonic drugs capable of increasing intracellular calcium concentrations. In actual fact, a better understanding of physiopathological mechanisms has led to the use of vasodilators, and these in turn have shed additional light on regional blood flows and on the role of the renin-angiotensin-aldosterone system. Added to the digitalis-diuretics therapy, vasodilators not only have beneficial effects on haemodynamic parameters and functional symptoms, but they reduce mortality in patients with CHF: recent studies have demonstrated an increase in survival as compared to conventional treatment. This has revived the problem of whether vasodilators should be prescribed in the early stages of CHF, either alone or combined with the usual drugs.

[Limitations of scintigraphy using metaiodobenzylguanidine for locating pheochromocytomas. Apropos of 2 cases]. / Limites de la scintigraphie à la MIBG pour localiser les phéochromocytomes. A propos de deux cas.

Two cases of MIBG (metaiodobenzylguanidine) scintigraphy are reported: the first case concerns a female patient hospitalized for high blood pressure (HBP) with symptoms evocative of pheochromocytoma. Urinary titration of catecholamines metabolites, which are usually abnormally high, and tomodensitometry permit the visualization of a left adrenal tumor. On the contrary, the MIBG scintigraphy does not show any abnormal fixation. After resection, the pathological examination confirms the diagnosis of pheochromocytoma. The second case concerns a female patient hospitalized for HBP with, on the chest X-Ray, a left postero-inferior density. Serum and urinary catecholamine levels are normal. Tomodensitometry confirms the tumor of the posterior mediastinum and the MIBG scintigraphy demonstrates a focus of thoracic opposite the tumor. After resection, the pathological examination shows an ectopic supernumerary bronchial bud. These two cases illustrate the limitations of MIBG scintigraphy to locate pheochromocytomas. There are false negative (10%) which may be explained by an insufficient uptake of the tracer by the tumor, by an insufficient image formation or by medication interferences. On the contrary, there may be false positives because of histochemical similarities between the chromaffin tissues and certain glandular or neural tumors. Nevertheless, in spite of serious limitations, which we must be aware of, MIBG scintigraphy remains the best primary examination for the location of pheochromocytomas.