Molecular dynamics studies of the interface between a model membrane and an aqueous solution.

Molecular Dynamics (MD) computer simulation studies are reported for a system consisting of two model membranes in contact with an aqueous solution. The influence of the membrane on the adjacent liquid is of main interest in the present study. It is therefore attempted to make the system sufficiently large to encompass the entire region between bulk liquid and the membranes. The latter are modeled by two-dimensional arrays of COO- groups with rotational and translational degrees of freedom. The water molecules are represented by the well-tested TIP4P model. The intermolecular potentials are parametrized in terms of Coulomb interactions between partial charges on the molecular frames and empirical, mostly Lennard-Jones (12-6), interactions centered at the atomic positions. A strong layering of the liquid accompanied by an increase in average water density is found in the vicinity of the membrane. The structural perturbation reaches approximately 8 A into the liquid. We discuss the static structure in these layers in terms of atom-atom distance distribution functions and study the average orientation of the water molecule dipoles with respect to the membrane. From the distribution of the ions, we find that less than 50% of the surface charge of the membrane is neutralized by Na+ ions in the first layer above the membrane. A simplified model of the adsorption site of the ion on the membrane is developed from the distance distributions. Finally the hydration of the Na+ in the first adsorbed layer is discussed.

Emergency balloon angioplasty and digital subtraction angiography in the management of an acute iatrogenic occlusive dissection of a saphenous vein graft.

A 63-year-old male with status post quadruple aortocoronary bypass surgery suddenly complained of chest pain and had ST-segment elevation in lead III during routine coronary angiography. Subsequent selective injections showed occlusion of the bypass graft to the right coronary artery, whereas by digital angiography done 15 min earlier it had been patient. Iatrogenic dissection of the graft was assumed, and balloon recanalization was immediately performed. Chest pain and signs of ischemia rapidly resolved, and no evidence of myocardial infarction was found until hospital discharge.

[Change in indications for coronary angiography in a decade]. / Changement des indications à la coronarographie au cours d'une décennie.

To characterize the changes in indications for coronary angiography we compared indications and therapeutic conclusions of cardiac catheterization, including coronary angiography, in 100 consecutive patients in 1975 and 100 consecutive patients in 1985. The baseline characteristics of the patients in the two groups were similar, except for age (50 +/- 10 vs 56 +/- 9 years, p less than 0.0001) and prior angioplasty (0 vs 12, p less than 0.0001). The main indications for coronary angiography in the two groups were (1975 vs 1985) chest pain in 67 vs 62 (n.s.), myocardial infarction in 10 vs 17 (n.s.), prior coronary surgery in 3 vs 0 (n.s.), major arrhythmias in 1 vs 1 (n.s.), and incidental (coronary pathology not the primary issue) in 19 vs 8 (p less than 0.05). We further analyzed each of the main indications in the two groups. Chest pain: angina ruled out in 21% vs 26% (n.s.), stable angina 64% vs 61% (n.s.), unstable angina 15% vs 13% (n.s.), positive non-invasive tests 39% vs 44% (n.s.). Myocardial infarction: acute intervention 0 vs 12% (n.s.), angina after infarction 20% vs 47% (n.s.), positive non-invasive tests after myocardial infarction 20% vs 41% (n.s.). Incidental: valvular heart disease 57% vs 63% (n.s.), cardiomyopathy 26% vs 13% (n.s.), congenital heart disease 11% vs 0 (n.s.), aortic dissection 5% vs 25% (n.s.), other 5% vs 0 (n.s.). Overall, clinical suspicion of coronary artery disease was confirmed and documented in 80% (65/81) vs 77% (61/79) of patients (n.s.), and normal coronary arteries were found in 20% (16/81) vs 23% (18/79) of patients respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

[Congenital intercoronary arterial anastomosis. Apropos of a case and review of the literature]. / Artère anastomotique intercoronaire congénitale. A propos d'un cas. Revue de la littérature.

The authors report a case of coronary arterial anastomosis between the right coronary and left circumflex arteries in the absence of other coronary pathology. This is an exceptionally rare congenital malformation which is situated either in the atrioventricular groove or at the apex in the interventricular groove. It constitutes a diagnostic pitfall because, in contrast to a collateral circulation, it is not an indirect sign of occlusive coronary artery.

[Cardiac failure caused by an overdose of dantrolene]. / Insuffisance cardiaque par surdosage en dantrolène.

A case is reported of cardiac failure with repeated pulmonary oedema in a female patient suffering from renal failure and having been given incremental doses of dantrolene sodium. On withdrawal of the drug, all symptoms disappeared. This muscle relaxant was considered not to have any depressive myocardial side-effects. However, recent studies on isolated myocardial fibres showed the existence of a constant dose-dependent negative inotropic effect of dantrolene sodium, only noticeable with high concentrations of the drug.

Acute hemodynamic effects of intravenous amiodarone in patients with coronary artery disease.

The acute hemodynamic effects of intravenous amiodarone (Cordarone injectable; Labaz) were studied during cardiac catheterization in 16 male patients with coronary artery disease (age range, 38-64 years; mean, 53 years). Amiodarone was administered as a bolus at a dosage of 5 mg/kg bodyweight over a 1-min period. Measurements were made 5, 10, and 15 min thereafter. The drug had little effect on heart rate, aortic pressure, cardiac index, and vascular resistances. There were small and nonsignificant increases in left ventricular end-diastolic pressure and end-diastolic volume. The ejection fraction decreased slightly and not significantly. In addition to some increases in pulmonary wedge, pulmonary artery, and right atrial pressures, the significant findings were a 15% decrease in maximal dP/dt and a 12% decrease in left ventricular work. These changes point to a slight negative inotropic effect of amiodarone.

[Volume and regional contraction of the left ventricle studied with venous injection in subtraction angiography]. / Volumes et contraction régionale du ventricule gauche par injection veineuse en angiographie numérique.

UNLABELLED: The end-diastolic and end-systolic volumes, the left ventricular ejection fraction, and segmental contraction of the left ventricle (5 areas) were determined at rest in 31 patients using two methods: conventional cineventriculography (as reference) and digital subtraction angiography by venous injection (the inferior vena cava). RESULTS: the volumes and ejection fraction obtained by digital subtraction angiography were reliable, though slightly less accurate than conventional ventriculography. Quantification of segmental contraction was satisfactory in the apical, anterolateral, and anteroinferior portions. It was less satisfactory in the posteroinferior portion with questionable reliability in the diaphragmatic portion. Qualitative dynamic assessment of contraction was satisfactory in most patients.

Non-selective intra-arterial digital subtraction angiography for the assessment of coronary artery bypass grafts.

Non-selective intra-arterial digital subtraction angiography (DSA) was performed immediately before selective coronary and bypass angiography in 33 consecutive symptomatic patients 48 +/- 30 months after coronary surgery, for the assessment of 75 coronary bypass grafts. Forty ml of non-ionic, low-iodine content contrast medium (iohexol) were injected into the ascending aorta at 10-20 ml/sec through a 7 or 8 F femoral pigtail catheter. Electrocardiogram-triggered images were acquired on a Siemens Digitron II apparatus in multiple projections in 24 patients and in a single projection in 9 patients. The results of this technique were compared by two independent angiographers with those of selective graft angiography in the same patients. Patency was shown by DSA in 45 of 54 grafts confirmed to be open by selective angiography (sensitivity 83%). Of 21 occluded grafts, stumps were clearly visible at selective angiography in 18 and at DSA in 9 (sensitivity for graft stumps = 50%, p less than 0.01). Of 54 patent grafts with selective angiography, the distal anastomosis could be visualized by DSA in 28 (52%), but the resolution was comparable to selective angiography in 20 grafts (37%) only. A non-significant difference in the sensitivity of DSA was observed between patent saphenous grafts to the left anterior descending coronary artery versus all other coronary arteries (95 vs 85%, respectively), while only 1 of 5 patent left internal mammary artery grafts to the left anterior descending coronary artery was visualized. In 16 of 50 grafts (32%) visualized in a second projection substantial additional diagnostic information was obtained. In conclusion, non-selective intra-arterial electrocardiogram-triggered DSA can visualize patent saphenous grafts with a high sensitivity and may be a useful screening tool for bypass grafts patency; false negatives, however, and poor visualization of distal anastomoses limit its routine clinical use.

[Global ventricular function and synchronism of contraction during and after exertion]. / Fonction ventriculaire globale et synchronicité de contraction pendant et après l'effort.

Phase analysis and ejection fraction (EF) of the left ventricle were obtained by radionuclide angiography in 53 patients at rest, during submaximal exercise and 3-8 minutes after exercise. The standard deviation of the peak of the histogram of phases (SDP) was used as an index of the synchronicity of regional contraction. The material comprised 13 sportsmen and 40 patients who underwent coronarography, 12 of whom had normal coronaries and 28 significant lesions. EF, while comparable in the three groups at rest, increased significantly on effort in normals and did not change in patients with coronary disease. At rest SDP was higher in coronary patients than in normals (p less than 0.01), and during exercise, it increased, but decreased in normals (p less than 0.01). After exercise, mean EF decreased in comparison with exercise in normals (p less than 0.01), while the opposite was the case in coronary patients. Normals had lower SDP values in the post-exercise period than at rest; on the other hand, SDP of coronary patients was significantly higher in the post-exercise period than at rest (p less than 0.001). Phase analysis during, and particularly after, exercise was found to be superior to EF in detecting ischemic left-ventricular dysfunction, and should be used in conjunction with EF to evaluate patients suspect for coronary disease.

[Angiographic study of the dynamics of the interventricular septum]. / Etude angiographique de la dynamique du septum interventriculaire.

The interventricular septum was studied by biventricular angiography in 52 patients divided into 4 groups: the first group consisted of 14 normal subjects; the second of 10 patients with hypertension (9 cases) or aortic stenosis (1 case); the third, of 19 patients with echocardiographic asymmetric septal hypertrophy, and the fourth, of 9 cases of cardiomyopathy with dilatation. The following parameters were measured: septal thickness at 4 different points and mean septal thickness, the height (long axis) and surface of the septum in diastole and systole. The percentage variation was calculated. There were no significant differences between Group I and II; there was a significant difference (p less than 0,01) in the variations of septal thickness of the upper segments between Group I and III. This difference remained significant (p less than 0,05) for the variations of mean thickness between Group I (-38%) and Group III (-18%). There was also a significant difference (p less than 0,05) in the variation of height between Group I (23%) and Group IV (9%). None of the variations of septal surface reached the threshold of statistical significance between the four groups. Biventricular angiography can therefore demonstrate certain abnormalities of septal motion. In asymmetric septal hypertrophy, the variations in thickness are significantly less pronounced than in normal subjects but the motion in the longitudinal axis does not differ significantly. In cardiomyopathy with dilatation, however, the variation in septal height is the most affected parameter.

[Surgical correction of interventricular communication with pulmonary stenosis in a hemophiliac]. / Correction chirurgicale d'une communication interventriculaire avec sténose pulmonaire chez un hémophile.

Open heart surgery was performed in a 5 year-old boy with severe hemophilia A and large ventricular septal defect with pulmonary stenosis. High doses of Factor VIIIC superconcentrates delivered as small transfusion volumes allowed the use of extracorporeal circulation with heparin. Transfusions began 5 hours before surgery and were stopped 21 days later. No adverse reaction was observed. Thus major surgery is possible in severe hemophiliacs provided strict rules for replacement therapy are followed.

[Value of computer tomography compared to angiography and echocardiography in the diagnosis of intracardiac thromboses]. / Valeur de la tomodensitométrie par rapport à l'angiographie et à l'échocardiographie dans le diagnostic des thromboses intracardiaques.

Until recently the only means of diagnosing intracardiac thromboses were angiography and M mode and 2D echocardiography. The aim of this study was to assess the value of CAT scanning in this field and to compare it with angiography and ultrasonography. Twenty intracardiac thromboses were studied in 19 patients by CAT scanning: 14 in the left ventricle, 2 in the right ventricle, and 4 in the left atrium, one patient having both left and right ventricular intracavitary thrombosis. M mode and 2D echocardiography and angiography were carried out whenever possible. Although for different practical reasons all patients did not undergo all three investigations, CAT scanning appeared to be the most reliable diagnostic method in intracardiac thrombosis, being more specific than either angiography and ultrasonography. In addition, the therapeutic effects of anticoagulant therapy on the thrombus can be assessed and other associated pathology such as aneurysm, pericardial reaction, dilatation of the cardiac cavities, myocardial and valvular calcification can also be demonstrated.

Diastolic mitral gradient without associated valvular stenosis: usefulness of two-dimensional echocardiography for a correct diagnosis.

A diastolic gradient across the mitral valve is generally indicative of mitral valve stenosis. In the present study, echocardiography was used to demonstrate two less common causes of left ventricular inflow obstruction: one patient had a fibromuscular membrane beneath the valve, the other a large vegetation attached to the posterior leaflet of the mitral valve. Echocardiography proved to be the optimal imaging technique in each case.

Association of coarctation of the thoracic aorta with fibromuscular dysplasia of the renal arteries: a case report.

The case of a 25-year-old woman with coarctation of the thoracic aorta and combined bilateral fibromuscular dysplasia of the renal arteries is reported. Although marked hemodynamic changes induced by the coarctation were probably pre-existent, hypertension was revealed only during the last month of her first pregnancy and was spontaneously corrected 2 months post partum. Surgical treatment of the thoracic coarctation did not influence blood pressure which remained normal.

Acute hemodynamic effects of intravenous tiapamil in patients with coronary artery disease.

The acute hemodynamic effects of intravenous tiapamil were studied during heart catheterization in 19 patients with coronary artery disease (age range 41-66 years, mean 52.4 years). 10 subjects received an initial intravenous loading dose of 1 mg/kg followed by intravenous infusion of 50 micrograms/kg/min for 15 min. The other 9 patients received an initial intravenous dose of 1.5 mg/kg which was followed by an intravenous infusion of 75 micrograms/kg/min for 15 min. Tiapamil had little effect on heart rate, intracardiac pressures and left ventricular dp/dtmax. The ejection fraction increased, but not significantly. The most striking findings were an increase in cardiac output and a decrease in systemic vascular resistance. The overall results are consistent with the drug's propensity to produce peripheral vasodilatation which outweighs its intrinsic negative inotropic property due to calcium antagonism in myocardial tissues.

Dissection of ascending aorta. Rare complication of aortocoronary venous bypass surgery.

Dissection of the ascending aorta is a rare complication of aortocoronary bypass surgery. A 63-year-old man who had received a double graft was found to have dissection of the ascending aorta, which was shown angiographically four months after operation. Since the patient was asymptomatic, operation was postponed. He has been followed up regularly and two years later his condition is still satisfactory.

[Physical training in high altitude]. / Entraînement physique et haute altitude.

Hemodynamic parameters and myocardial extraction of lactate and free fatty acids (FFA) have been studied at rest and during exercise (bicycle) in 9 mountain climbers who spent 4 weeks in the Himalayas at an altitude of 5500-7000 m. All investigations were performed before and immediately after the stay at high altitude. The combined effect of physical training and hypoxemia of high altitude did not alter the hemodynamic parameters, calculated VO2 max, production of lactate or decrease of FFA during the exercise test, but myocardial extraction of lactate and FFA changed. After returning from the expedition myocardial extraction (at rest and during exercise) of lactate increased and that of FFA decreased. The reasons for these alterations and their goals and implications are discussed.