Effect of delayed percutaneous transluminal coronary angioplasty of occluded coronary arteries after acute myocardial infarction.

Whether angioplasty of occluded vessels after myocardial infarction may have beneficial effects on left ventricular function remains unknown. Patients with a first myocardial infarction and thrombolytic therapy who had an occluded infarct-related vessel at delayed coronary angiography were referred systematically for an elective coronary angioplasty performed between 3 and 4 weeks after the myocardial infarction. All patients underwent stress-redistribution-reinjection thallium-201 single-photon emission computed tomography for myocardial viability assessment. Prior angioplasty, a quantitative evaluation of global and regional left ventricular function, was performed. The study group consisted of 38 patients (aged 57 +/- 10 years); 18 had anterior wall infarctions and 20 inferior wall infarctions, but before angioplasty 3 had a patent artery and were excluded. Angioplasty was successful in 30 patients. At follow-up 13 patients (43%) had an occluded coronary artery. In contrast with patients with an occluded coronary artery at follow-up, those with a patent coronary artery had no left ventricular enlargement and had an improvement in both left ventricular ejection fraction (from 48 +/- 9% to 52 +/- 9.8%, p = 0.002) and regional wall motion index (delta = +0.95 SD, p <0.01). In patients with a patent vessel at follow-up, there was a positive correlation between the number of myocardial viable segments and improvement of the infarct zone wall motion (r = 0.52; p = 0.035), and the number of necrotic segments at baseline was positively correlated to the 4-month changes in end-diastolic volume indexes (r = 0.6; p = 0.04). Thus, elective revascularization of occluded coronary arteries with viable myocardium after myocardial infarction improves left ventricular function and lessens remodeling if the artery remains patent during follow-up.

Canine myocardial dihydropyridine binding sites: a positron emission tomographic study with the calcium channel inhibitor 11C-S11568.

The in vivo determination of the density of dihydropyridine (DHP) binding sites will allow the assessment of pathophysiological changes associated with heart disease. The calcium channel antagonist S 11568: (+/-)(amino-7 dioxa-2,5 heptyl)-2(dichloro -2,3 phenyl) -4 methyl-6dihydro -1,4 pyridine has an in vitro profile of high potency and of high selectivity for the L-type Ca2+ channel. S 11568 was labelled by a reaction between 11C-diazomethane and the precursor 6-(7-amino-2,5-dioxa heptyl)-4-(2,3-dichloro phenyl)-5-(ethoxycarbonyl)-2 methyl-1,4 dihydro nicotinic acid. (+)-PN 200 110, a DHP with in vitro high affinity for the L-type Ca2+ channel, was also radiolabeled. Positron emission tomographic (PET) studies of both 11C-DHP myocardial uptake were performed in Beagle dogs. 11C-(+)-PN 200 110 had a rapid wash-out from myocardium. In contrary, after a bolus injection, 11C-S 11568 myocardial concentration increased to reach a maximum in 1-2 minutes and then remained in a plateau with a slight downslope while the blood concentration fell rapidly. Myocardial uptake was 2 to 4 fold higher than lung uptake, leading to a good contrast on PET images. Pre-treatment with unlabeled S 11568 (2 mumol/kg or 6 mumol/kg over 15 minutes) reduced myocardial uptake by 60% and 80%, respectively. Specific binding was estimated during a displacement experiment: bolus of unlabeled S 11568: 1 mumol/kg followed by a continuous infusion of 3 mumol/kg over 2 hours. It was found to represent 80% of the total binding. To assess influence of S 11568 on coronary blood flow and therefore on the myocardial tracer delivery, coronary blood flow was measured using 15O-H2O and PET at baseline and following bolus injections of 0.4, 0.8, 2 mumol/kg of S 11568. Only the higher dose increased coronary blood flow. This is the in vivo demonstration of the binding characteristics to myocardial tissue of a DHP ligand. Such properties make S 11568 suitable for PET experiments. The studies of DHP binding sites will provided new insights concerning physiological situations as well as heart disease.

[Medical treatment after myocardial infarct: reflex prescription or thoughtful prescription]. / Le traitement médical après l'infarctus du myocarde: ordonnance réflexe ou ordonnance réfléchie.

There have been many therapeutic trials to determine the efficacy of given drugs prescribed after myocardial infarction. This may be explained by the very number of families of drugs which may intervene during the evolution of coronary artery disease. A common mistake is to think that the results of therapeutic trials can be automatically applied in clinical practice. In order for the demonstrated effect of a product to lead to its automatic prescription, there must be confirmation that the importance of the expected benefits does not depend on the type of infarction. This is probably the case for aspirin and the reduction of cholesterol levels which seem to be effective irrespective of the characteristics of the initial infarction. On the other hand, the efficacy or dangers of anti-ischaemic drugs, angiotensin converting enzyme inhibitors or antiarrhythmics, is very dependent on the impact of the infarct on left ventricular function. The prescription of drugs after myocardial infarction depends on individual parameters which lead to the adaptation of consensus recommendations to each particular case.

[Acquired pulmonary vein stenosis after surgery of complex partial anomalous pulmonary venous drainage in an adult. Diagnostic value of transesophageal echocardiography]. / Sténose acquise d'une veine pulmonaire après chirurgie d'un retour veineux pulmonaire anormal partiel complexe de l'adulte. Intérêt diagnostique de l'échocardiographie transoesophagienne.

Surgical correction of partial anomalous pulmonary venous drainage is difficult and may be complicated by acquired postoperative stenosis at the site of reimplantation of the pulmonary veins in the left atrium. Diagnosis should be made quickly because of the very poor prognosis due to acute pulmonary hypertension. The case described by the authors underlines the value of multiplane transesophageal echocardiography with two-dimensional and Doppler analysis for rapid and accurate diagnosis of this complication.

[Method of evaluation of relaxation and diastolic function]. / Méthode d'évaluation de la relaxation et de la fonction diastolique.

Impairment of relaxation and diastole is usual if not constant in cardiomyopathies and accompanies a disorder of cardiac contractile function. Certain heart diseases, especially hypertrophic cardiomyopathy, are associated with relative preservation of contractility and the predominant disorder concerns left ventricular filling. The clinical consequence of this impairment is dyspnoea due to elevated pressures of the left-sided cavities. The loss of atrial systole atrial is usually very poorly tolerated. There is an ambiguity of definitions, as, for the clinician, diastole starts at the time of closure of the aortic valve and consists of four phases: isometric relaxation, rapid ventricular filling, diastasis and atrial systole. In reality, this definition must be reviewed in physiological terms, asthe relaxation which allows the ventricle to return to its initial precontraction configuration is an active phenomenon which is actually part of ventricular systole. The reference methods of investigation remain haemodynamic methods with invasive measurements of left ventricular pressures and volumes. Myocardial isotope scan and especially echocardiography allow assessment of relaxation and diastole, although certain limitations of interpretation must be kept in mind. In terms of treatment, the demonstration of impairment of relaxation and diastole may require a different approach when contractile function is preserved. Calcium channel blockers could be useful and the preservation of atrial systole is always decisive.

[Medical treatment after implantation of intracoronary stents]. / Traitement médical après implantation de stents intracoronaires.

RATIONALE FOR ANTITHROMBOSIS THERAPY: Introducing a foreign body into the coronaries raises the risk of thrombosis in the acute phase and for the 4 following weeks. The objective of antithrombotic therapy is to inhibit platelet adhesion and aggregation or to induce hypocoagulability. AT IMPLANTATION: High-dose heparin is given in a bolus following pretreatment with aspirin. ASPIRIN-TICLOPIDINE COMBINATION: The risk of subacute thrombosis is low, about 1%, and the rate of vascular complications is minimal. Treatment is simple and compatible with short hospitalization.

[Different types of coronary stents]. / Les différents types de stent coronaire.

GENERAL CHARACTERISTICS: Several criteria are used for coronary stent design: biocompatibility, i.e. the capacity to resist thrombotic events and corrosion, flexibility, radial force sufficient to resist elastic recoil, percentage of the lesion covered, radio-opacity, minimal shortening at opening, absence of effect on collateral branches, possibility to use small calibre probe guides, and cost. TWO CATEGORIES: Both tubular stents (self-expanding stents and balloon stents) and filamentary stents (made of stainless steel or tantalum) are used, THE IDEAL STENT: There is no one ideal stent. Choice is dictated by the characteristics of the lesion and by the status of the artery to treat.

[Why so many stents?]. / Pourquoi autant de stents?

BETTER THAN ANGIOPLASTY: Prolonging inflation with a perfusion balloon decreases the risk of acute coronary occlusion after angioplasty. The longer the artery remains patent, the greater the chances of 0% residual stenosis. This is what the sent allows. Stent act on both mechanisms of stenosis: elastic recoil and fibrous remodeling of the arterial plaque. TARGETTED ACTION: Stents improve angioplasty prevention of acute stenosis. They have a real action on preventing degeneration of the saphenous graft and lead to a significant reduction in the rate of restenosis of the dilated site. There are however two specific complications: subacute occlusion and greater incidence of vascular events. Stents are particularly indicated for the treatment of restenosis and chronic occlusions. TWO IMPROVEMENTS: Risks related to the implantation of a foreign body in the vascular system have been reduced with the use of ticlopidine and high-pressure stent implantation. POSITIVE RESULTS: Stents have produced better angiographic results. They limit restenosis and the number of revascularizations required in treated patients. Several questions concerning indications remain open.

Iodine 123-labeled metaiodobenzylguanidine imaging in heart disease.

Scintigraphic images of myocardial iodine 123-labeled metaiodobenzylguanidine (MIBG) reflect the relative distribution of adrenergic neurodensity and function in the myocardium. In patients with hypertrophic cardiomyopathy or after infarction, MIBG uptake in hypertrophied myocardium and the infarct-related myocardium was found to be decreased in comparison to blood flow distribution, delineated with thallium 201. Most intriguingly, semiquantitative measurements in patients with congestive heart failure demonstrated reduced myocardial MIBG uptake. This reduction correlated directly with indexes of left ventricular function. Decreases in neuronal density, dysfunction of adrenergic neurons, or chronically elevated circulating norepinephrine levels may account for this diminished myocardial uptake, which, as demonstrated in a pilot study of 90 patients with congestive heart failure, was found to be of predictive value for survival.