Contrast-medium-induced ventricular fibrillation: arrhythmogenic mechanisms and the role of antiarrhythmic drugs in dogs.
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Animals↗
Biomedical subjects
T Lefevre
Publications and source records attributed to T Lefevre.
Safety and efficacy of the new iodinated nonionic low-osmolality contrast medium Iobitridol (Xenetix) in coronary and ventricular angiography.
PURPOSE: The aim of this phase-III clinical trial was prospectively to evaluate the clinical safety and diagnostic efficacy as well as the effects on laboratory and electrocardiographic parameters of new iodinated, nonionic, low-osmolality contrast medium, iobitridol(Xenetix 350) during coronary angiography in adults in comparison to an iodinated, nonionic, low-osmolality reference product, iohexol (Omnipaque). MATERIALS AND METHODS: This 2-center, comparative, randomized, double-blind trial involved 90 patients, 46 receiving iobitridol and 44 iohexol. Clinical safety was evaluated by recording the adverse events observed during investigation and by the patient's assessments. Electrocardiographic effects on laboratory parameters were evaluated as well as diagnostic efficacy. RESULTS: The age, sex, presence of risk factors and clinical picture ( unstable angina, postinfarction) were not significantly different between the 2 treatment groups. The incidence of significant coronary lesions (stenosis 50%) was also not significantly different between the 2 treatment groups. Clinical safety was good in both groups. Four patients experienced an adverse event, 2 in each group. In the iobitridol group, one patient had an episode of hypertension, followed by hypertension and prolonged chest pain was observed and one patient had sinus tachycardia. In the iohexel group, chest pain was observed in one patient and nausea in another. ECG safety was good in both groups. Transient excitability disorders were observed in 10 and 6 patients, respectively. Moderate conduction abnormalities were noted in one patient in each group and repolarization abnormalities in 10 and 8 cases, respectively. Safety in laboratory parameters was good with no significant changes in either. Diagnostic efficacy was good to excellent in all patients. CONCLUSION: Diagnostic efficacy and safety of iobitridol 350 in terms of effects on clinical, laboratory and electrocardiographic parameters were comparable to those of the nonionic reference product.
Contrast Media↗
[Coronary artery stenting without antivitamin K. Results after a month].
This paper reports experience with a new antithrombotic agent prescribed to reduce the incidence of subacute occlusions during the first month after coronary stenting. Therefore, a powerful association of platelet antiaggregant agents was tested. From December 1992 to October 1994, coronary stenting was successfully achieved in 1,294 patients (1,118 men, average age 60.5 +/- 10 years) who were then treated with the association of ticlopidine 0.25 g/day and aspirin 0.10 g/day for one month. This was covered with anticoagulation with a low molecular weight heparin for a variable period (one month, two weeks, then one week), according to the different phases of the study protocol. In all, 1487 stents were successfully implanted (1,330 Palmaz Schatz; 63 Cook; 80 Wictor; 13 AVE and 1 Strecker) in 1,326 vessels (520 left anterior descending, 208 left circumflex, 475 right coronary, 16 left main coronary arteries and 107 venous grafts) using balloon catheters of 2.5 mm to 5 mm diameter for average 3.45 +/- 0.4 mm). Major complications in the first month included 9 deaths (0.7%), 22 occlusions (1.7%): 14 myocardial infarcts (1%) and 11 aorto-coronary bypass procedures (0.85%). There were 136 local haematomas or false aneurysms (10.5%), 42 of which (3.25%) required blood transfusion or surgical repair. This multicenter trial of a protocol associating platelet antiaggregant agents and low molecular weight heparin for one month showed a low incidence of subocclusion after coronary stenting (1.7 +/= 2.5%) and should enable interventional cardiologists to widen the indications for coronary stenting.
Adult↗
[Restenosis on coronary endoprosthesis: treatment by implantation of a new endoprosthesis. Apropos of a case].
A 60-year-old man was admitted to hospital with threatened anterior myocardial infarction due to double tight stenosis in the 1st and 2nd segments of the left anterior descending artery. This double stenosis was successfully treated, without any complications, by two Palmatz-Schatz 15.4 mm (PS 154 A) coronary stents. He was readmitted to hospital six months later for another episode of threatened anterior infarction, due to restenosis involving the 2 coronary stents. Balloon angioplasty of this restenosis was attempted, but the poor result led us to insert 2 contiguous articulated Palmatz-Schatz 154 mm stents (PS 154 A) inside the previous two stents. The result was excellent with no complications apart from distal dissection induced by the guide, requiring insertion of an AVE Stent, 8 mm long and 3 mm in diameter. An exercising myocardial scintigraphy performed one month after the procedure was normal. The patient is still asymptomatic with a follow-up of 6 months. The feasibility and low risk of complication of balloon angioplasty in the case of restenosis, after insertion of an intracoronary stent have been demonstrated by several studies. To our knowledge, no case of restenosis of an intracoronary stent, treated by insertion of a new stent, have been reported. We report a case of restenosis on two Palmatz-Schatz stents successfully treated by insertion of two contiguous PS 154 A stents.
Angioplasty, Balloon, Coronary↗
Divalent cation channels activated by phenothiazines in membrane of rat ventricular myocytes.
Phenothiazines (PTZ) such as chlorpromazine (CPZ) or trifluoperazine (TPZ) induced a sustained divalent cation-permeable channel activity when applied on either side of inside-out patches or on external side of cell-attached patches of adult rat ventricular myocytes. The percentage of active patches was approximately 20%. In the case of CPZ, the Kd of the dose-response curve was 160 microM. CPZ-activated channels were potential-independent in the physiological range of membrane potential and were permeable to several divalent ions (Ba2+, Ca2+, Mg2+, Mn2+). At least three levels of currents were usually detected with conductances of 23, 50 and 80 pS in symmetrical 96 mM Ba2+ solution and 17, 36 and 61 pS in symmetrical 96 mM Ca2+ solution. Saturation curves corresponding to the three main conductances determined in Ba2+ symmetrical solutions (tonicity compensated with choline-Cl) gave maximum conductances of 36, 81 and 116 pS (with corresponding half-saturating concentration constants of 31.5, 38 and 34.5 mM). The corresponding conductance values were estimated to 1.7, 3.3 and 5.2 pS in symmetrical 1.8 mM Ba2+ and to 1.1, 2.4 and 3.7 pS in symmetrical 1.8 mM Ca2+ (the value in normal Tyrode solution). Channels were poorly permeable to monovalent cations, such as Na, with a PBa/PNa ratio of 10. A PTZ-induced channel activity similar to that described in cardiac cells was also observed in cultured rat aortic smooth muscle cells but not in cultured neuroblastoma cells. PTZ-activated channels described in cardiac cells appear very similar to the sporadically active divalent ion permeable channels described in a previous paper (Coulombe et al., 1989). Surprisingly, when 100 microM CPZ were applied to myocytes studied in the whole-cell configuration, and maintained at a holding potential of -80 mV in the presence of 24 mM external Ca2+ or Ba2+, no detectable macroscopic inward current could be observed, whereas the L-type Ca2+ current triggered by depolarizing pulses was markedly and reversibly reduced. The possible reasons are discussed.
Animals↗
[Intercoronary anastomoses of congenital origin. Apropos of a case].
Homo- or heterolateral intercoronary anastomoses are usually present in the normal heart. Owing to their small caliber they cannot be visualized at coronary arteriography, but they may become visible in case of obstructive coronary lesion. Congenital intercoronary anastomoses are entirely different. A case of intercoronary anastomosis between the right coronary artery and the circumflex artery, without any coronary lesion, is presented. This is an exceptional variant, only 12 cases of which were found in the literature. The anastomosis was located in the atrioventricular sulcus in 11 cases and in the interventricular sulcus in 1 case. This "abnormality" can be distinguished from collateral arteries by its angiographic features, and it does not reflect an underlying coronary disease. It may play a protective role if lesions develop on one of the two vessels it links together.
Adult↗
[Myocardial infarction during or after exertion related to sports. Clinical and coronary angiographic analysis of 10 cases].
The purpose of this study was to analyse characteristic of myocardial infractions that occur during, or immediately after sport-related exertion in subjects who are neither athletes nor professional sportsmen and who undergo coronary angiography. Ten cases where myocardial infraction developed during (n = 3) or immediately after (n = 7) a game were studied retrospectively. All patients were men aged from 21 to 61 years (mean 48.8 years); 8 of them were smokers and 5 had hypercholesterolaemia. The sports practised were tennis (3), cycling (2), football (2), skiing (2) and weight-lifting (1). The infarction was inferior or basal in 5 cases, lateral in 1 case and anterior or anteroseptal in 4 cases. Coronary lesions involved one vessel in 6 and two vessels in 2 patients aged from 47 to 61 years. They were absent in 2 patients aged 24 and 26 respectively, with methylergonovine-induced spasm in one case. The outcome over a 2.9 years follow-up period was favorable, except for one death 6 months after the infarction (patient aged 24, normal coronary arteries, spasm). The outstanding features in this study are: (1) the occurrence of infraction during the recovery period and the noxious role played by smoking; (2) the contrast between the presence of atherosclerotic coronary lesions in middle age subjects and their absence in younger subjects (infarction due to spasm or thrombosis?), and (3) the possible usefulness of an exercise test in sport players of more than 40 years of age.
Adult↗
[Value of the calibration of coronary angioplasty balloons].
A total of 197 polyethylene balloons of 2 to 4 mm diameter were inflated to 1 to 10 atmospheres to determine the variations of size with respect to pressure of inflation. A linear relationship was observed between diameter and pressure of inflation. The slope of this relationship represents the compliance. Balloons of the same diameter have almost identical compliances. The compliance of the balloon increases with size. The specified diameters are obtained with pressures of less than 6 atmospheres. However, the variations of size of a given balloon are important. This study shows that attention should be paid to the calibration of balloon catheters before angioplasty to avoid the risks of over-dilatation. New balloons made of therephtalane polyethylene are much less compliant and do not present this type of problem.
Angioplasty, Balloon, Coronary↗
[Left coronaro-ventricular microfistula].
Microfistulae between coronary arteries and left ventricle have long been regarded as mere curiosities, but their frequency seems to have been underestimated. A review of 2,520 consecutive coronary arteriographies performed in adults has yielded 34 cases. In most of the 28 patients without infarction or valve disease, the symptoms were suggestive of coronary pathology. Signs of ischaemia were found at electrocardiography in 19 of these 28 patients, and exercise tests or myocardial scintigraphy were positive in 2 out of 3 cases. Patients' mean age was 53.4 years. The coronary arteriographic diagnosis was usually easy when technical conditions were perfect. The division of patients into two groups according to the presence or absence of significant coronary lesions revealed that the "isolated microfistulae" group was primarily composed of women (19/21). It is generally accepted that these fistulae are of embryonic origin, but their relation to atherosclerosis needs to be determined. The causes of ischaemic manifestations (coronary artery steal, global disturbances of myocardial microcirculation) are considered. Treatment is essentially medical, surgery being exceptional. Prognosis is habitually favourable (mean follow-up 28.3 months in our series). Thus, microfistulae between coronary arteries and left ventricle usually present as angina-like symptoms in women in their fifties who are free from atheromatous disease. They are found in more than 1 p. 100 of coronary arteriographies in adults, i.e. 8 p. 100 of "normal" coronary arteriographies. Their origin, the mechanisms of their symptoms and their relationship with the "so-called healthy coronary arteries angina" are obscure.
Coronary Angiography↗
[Left coronaro-ventricular microfistulas. Apropos of 25 cases].
A retrospective study of 25 patients with left coronaroventricular microfistulae, investigated in the same vascular radiologic exploration unit, and data in the international literature were used to analyze these lesions in greater detail. Their frequency appears to have been underestimated since they represented 1.33% of coronarographies performed in adults in this series. Distribution into two groups as a function of presence or absence of significant coronary lesions, vascular disease or myocardial insufficiency showed that the group with isolated microfistulae was composed solely of women of about 50 years of age (16 cases). These patients presented typical angina with a simple course (absence of infarction), but a sometimes severe disability due to the symptomatology. The myocardial ischemia could result from a "coronary steal" phenomenon but other hypotheses have been evoked. Their congenital origin is widely accepted but their relation to atherosclerosis has not been established (cause, consequence or fortuitous association). They present specific images on routine coronarography. Treatment is symptomatic but surgical in exceptional cases with refractory, very disabling angina. Finally, detection of left coronaroventricular microfistulae should, when combined with metabolic studies, allow classification of the difficult problem of "angina with angiographically normal coronary arteries".
Aged↗
Stroking parameters in front crawl swimming and maximal lactate steady state speed.
In order to increase or maintain speed at sub-maximal intensities, well-trained swimmers have an increase in their stroke rate, thus a decrease in their stroke. The purposes of this study were i) to ascertain whether the maximal speed from which the stroke length decreases significantly (SSLdrop) corresponds to the maximal lactate steady state swimming speed (SMLSS), and ii) to examine the effect of the exercise duration on the stroking parameters above, below, and at SMLSS. Eleven male well-trained swimmers performed an all-out 400-m front crawl test to estimate maximal aerobic speed (MAS) and four sub-maximal 30-min tests (75, 80, 85, and 90 % MAS) to determine SMLSS and SSLdrop and to analyse the evolution of the stroking parameters throughout these tests. SMLSS (88.9 +/- 3.3 % MAS) and SSLdrop (87.3 +/- 4.5 % MAS) were not significantly different from each other (p=0.41) and were highly correlated (r=0.88; p <0.001). Moreover, a slight stroke rate increase, and a stroke length decrease, were observed above S (MLSS) but were only significant for the 5 swimmers unable to maintain this speed for 30 min (p >0.05). During the 30-min tests swum below and at SMLSS, a steady state of stroking parameters was statistically reported. Thus, SMLSS seems to represent not only a physiological transition threshold between heavy and severe sub-maximal intensities but also a biomechanical boundary beyond which the stroke length becomes compromised.
Adult↗