[Acute myocardial infarction: recent physiopathological data. 1: acute coronary occlusion]. / Infarctus myocardique aigu: données physiopathologiques récentes. Première partie: l'occlusion coronaire aiguë.

Acute myocardial infarction is the result of sudden coronary occlusion in the absence of a collateral circulation. There main factors are required for this to occur: an acute parietal lesion on a stenosis of variable, sometimes minor, importance; local coronary vasoconstriction and a platelet and fibrin thrombus. Parietal fissuration is the commonest "trigger" of coronary spasm and the thrombotic cascade. All factors of coronary occlusion are potentially reversible--vasodilation--platelet anti-aggregation--physiological fibrinolysis--remodeling and cicatrisation of the plaque, thereby explaining cases of spontaneous regression of occlusion (10% at 1 hour; 20% at 6 hours; 30% at 24 hours; 50 to 70% at 1 year). The pathogenesis of myocardial infarction with angiographically normal coronary arteries may be reviewed and attributed to acute parietal fissuration at a non-significant or angiographically undetectable plaque resulting in occlusive thrombosis. In this case, the role of other pathogenic factors is also discussed (diabetes, oral contraception, haemostatic abnormalities, platelet disorders...).

[Acute myocardial infarction: recent physiopathological data. 2: Left ventricular function]. / Infarctus myocardique aigu: données physiopathologiques récentes. Deuxième partie: la fonction ventriculaire gauche.

Myocardial infarction is an anatomical and therefore functional amputation of some of the myocardial tissues. Moments after acute coronary occlusion, a cascade of metabolic, mechanical and electrical ischaemia related events is observed. Contraction stops and regional left ventricular akinesis (then dyskinesis) occurs in the zone at risk of irreversible myocardial damage. This is partially compensated by hyperkinetic motion of non-ischaemic myocardium. The degree of alteration of the global ejection fraction is the resultant of these akinetic and hyperkinetic wall motions. It is lower in cases of anterior myocardial infarction, of occlusion of the proximal segment of the left anterior descending artery and of multivessel disease. Its eventual outcome depends on coronary blood flow. If the artery responsible is recanalized early, the global ejection fraction stabilises or improves. When this does not happen, the global ejection fraction decreases. The end-diastolic volume, an indicator of left ventricular remodeling, increases in relation to the size of the infarct and to the persistence of coronary artery occlusion. The delay before the appearance of the first irreversible lesions, the rate of their propagation within the myocardial wall and the presence of reperfusion lesions are poorly understood factors in the clinical setting and influence the efficacy of methods of myocardial protection.

[Left-right shunt caused by anomalous implantation of the left coronary artery in the trunk of pulmonary artery. Detection by contrast echocardiography]. / Shunt gauche-droite par anomalie d'implantation de l'artère coronaire gauche dans le tronc de l'artère pulmonaire. Détection par échocardiographie de contraste.

The authors describe a case of an anomalous left coronary artery arising from the main pulmonary artery in an 11 year old child suffering from chest pain on effort and with a continuous murmur in the second left intercostal space. Two dimensional echocardiography (2D E) showed dilatations of the first segment of the right coronary artery and the anomalous origin of the left main coronary artery. A peripheral injection of microbubbles showed a left-to-right shunt between the left coronary artery and the pulmonary artery. Semi-quantitative evaluation of LV regional wall motion showed abnormal contraction of the anterolateral walls. Haemodynamic, angiographic data and the operative findings confirmed the diagnosis. The abnormal coronary ostium was closed and a bypass graft from the aorta to the left anterior descending artery was performed. Clinical and echocardiographic follow-up 7 months after surgery was completely normal.

[Echocardiography of an operated case of a myxoma of the tricuspid valve]. / Echographie d'un myxome de la valve tricuspide opéré.

The case of a 6 year old child with a tricuspid valve myxoma is presented. Early diagnosis by echocardiography, confirmed by angiography, resulted in surgical cure before any symptoms appeared. This is the only reported echocardiographic study of a myxoma inserted on the tricuspid valve found in a review of the literature of 6 cases of right ventricular myxoma. The tricuspid valves were found to be thickened and prolapsed into the right atrium. The amplitude of excursion of the anterior leaflet was greatly increased, its mass projecting into the right ventricular outflow tract in diastole and remaining there until the end of right ventricular ejection. The echocardiographic signs localising the precise origin of the tumor in the tricuspid valve are developed. The differential diagnosis with right atrial myxoma prolapsing into the ventricular cavity, benign and malignant right ventricular tumours and tricuspid valve vegetations is discussed. The precision of the diagnostic information obtained by echocardiography suggests that angiography may not be essential any longer, especially when the risk of embolisation and acute obstruction are taken into consideration.