Clinical comparison of mitral valve replacement using porcine, Starr, and Bjork valves

The choice of a cardiac prosthesis for mitral valve replacement remains controversial, and thromboembolic complications are still a major cause of morbidity and mortality in patients with mechanical valves. Because of this, permanent anticoagulation with its risks and constraints on daily life is necessary. Bioprostheses, however, are associated with a lower rate of thromboembolic events. Therefore, the need for long-term anticoagulation is minimized. These advantages are counterbalanced by the limited durability of tissue valves. In an effort to give some perspective to this balance, we compared the long-term results of three commonly used mitral valve prostheses. Three hundred patients operated on in the same institution January 1974 to December 1978 form the basis of this evaluation.

Left ventricular outflow obstruction after mitral valve repair (Carpentier's technique). Proposed mechanisms of disease

Left ventricular outflow tract obstruction (LVOTO) after mitral valve repair by Carpentier's technique has been recently reported in the literature. To assess the mechanisms of this phenomenon, we investigated 307 mitral valve repairs performed between July 1985 and December 1986. Incidence of LVOTO related to the mechanism of the mitral insufficiency and to the etiology demonstrates a direct relation to preoperative mitral valve prolapse (posterior leaflet +/- anterior leaflet) of degenerative origin. No LVOTO occurred after rheumatic mitral insufficiency repair regardless of size of the left heart cavities or of the prosthetic ring. Intraoperative and surficial two-dimensional echocardiography, color Doppler methods, and cardiac catheterization were used to investigate the mechanisms leading to LVOTO. Nonspecific modifications induced by reduction in size of the mitral annulus by the prosthetic ring (anterior displacement of the posterior ventricular wall and of the posterior mitral leaflet and narrowing of the mitroaortic angle) are not sufficient to explain the LVOTO. The association of mitral leaflets (composed of excess tissue and opposed to flow by a perpendicular position attributable to a narrow mitroaortic angle) and geometric left ventricular modifications (responsible for the superposition of mitral inflow to ventricular outflow) also qualifies as a mechanism for the induction of LVOTO after mitral surgical repair.

[Mechanical methods of treating refractory cardiac failure]

Mechanical means tend to be used more frequently nowadays for the treatment of congestive heart failure which does not respond to more normal treatment. The indications and limits of such devices, as well as their cost, must be defined. The new problem created by these therapeutic tools is the evolution of the underlying cardiac disease: should it improve the patient will be weaned from the machine, whereas if it worsens heart transplantation would be the only answer. Three types of mechanical support are described. Balloon pumping, and especially intra-aortic balloon pumping, is the technique used most often. It has a true but limited efficacy. Its best indication is cardiogenic shock by left ventricular ischaemia with normal or slightly increased peripheral resistances. Intrapulmonary balloon pumping is occasionally used, but the system can only be set up surgically. Its best indication would seem to be right-sided heart failure by pulmonary hypertension. Circulatory assistance is the second type considered. All types of bypass pumps can be used. The output used is usually less than the patient's theoretical output, the aim being to allow the myocardium to recover. Vascular access for these pumps is either femoral or intrathoracic. An oxygenator may or may not be added to the bypass circuit, and support may be mono- or biventricular. Although the non pulsatile flow has not been shown to be detrimental, this has to be investigated further. The use of these devices is limited by their effects on blood coagulation and pulmonary function. The artificial heart or artificial ventricles are the last devices described.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of Mg-ATP hydrolysis in isolated Rhodospirillum rubrum H+-ATPase

The effects of lauryl dimethylamine oxide on the Rhodospirillum rubrum H+-ATPase have been studied. This detergent activates Mg2+-dependent ATP hydrolysis in the isolated R. rubrum F0-F1 34-fold, whereas the Ca2+-ATPase activity is only slightly modified. ATPase activation by lauryl dimethylamine oxide enhances the effect on ATP hydrolysis exerted by free Mg2+ ions. Concentrations of free Mg2+ in the range of 0.025 mM favor activation while higher concentrations inhibit ATPase activity by approximately 70%. Steady-state kinetic analysis shows that lauryl dimethylamine oxide induces a complex kinetic behavior for Mg-ATP in the chromatophores, similar to the untreated F0-F1 complex. The initial rate value for Mg-ATP unisite catalysis was found to be 6.3 times higher (3.5 X 10(-3) mol Pi per mol R. rubrum F0-F1 per second) in the presence than in the absence of detergent, where the initial rate was 5.5 X 10(-4) mol Pi per mol R. rubrum F0-F1 per second. These experiments show that lauryl dimethylamine oxide shifts the cation requirement for ATP-hydrolysis of the isolated R. rubrum H+-ATPase from Ca2+ to Mg2+ and that it activates both multisite and unisite catalysis. Results are discussed in relation to the possibility of a regulatory role by Mg2+ ions on ATP hydrolysis expressed through subunit interactions.

Structural and functional differences in H+-ATPases with native and reconstituted inhibitor protein

Anti F1 antibodies that react with the alpha and beta subunits of the mitochondrial F0-F1 ATPase complex do not interfere with the natural inhibitor protein-ATPase interaction as revealed by inhibitor peptide titration curves. Submitochondrial particles with endogenous or added bound inhibitor protein show differences in immunoprecipitation. Submitochondrial particles which are partially depleted of inhibitor protein gave the same immunoprecipitation curve as the Mg-ATP particle. Anti F1 antibodies induce differential effects in ATP hydrolysis and ATP-Pi exchange. ATP hydrolysis is stimulated in Mg-ATP particles to 200%, while inhibitor depleted and inhibitor reconstituted particles are inhibited by the presence of the antibodies. ATP-Pi exchange is stimulated in inhibitor reconstituted particles and inhibited in Mg-ATP and inhibitor depleted particles. These results suggest that the inhibitor protein when endogenously bound confers a different conformation to the F1-ATPase than that of the F1 ATPase with added bound inhibitor protein.

Porphyrin content of the cysticercus of Taenia solium

The strong red fluorescence of the cysticercus of Taenia solium depends on the presence of several porphyrins in the vesicular fluid of the parasite: probably protoporphyrin IX, coproporphyin I or III, and 2 decarboxylated porphyrins intermediate between uroporphyrin and coproporphyrin. Cyst porphyrins associated to form conglomerates of high molecular weight that dissociated in acid solutions and were not antigenic themselves nor associated with antigenic molecules. An appreciable fraction of the porphyrins was capable of undergoing oxidation and reduction, indicating that some of the porphyrins were complexed with metal ions. The metabolic basis for the accumulation of porphyrins is unknown. Preliminary results suggest that conditions deleterious to the cysticercus cause release of porphyrins so that the appearance of porphyrins in the cerebrospinal fluid of neurocysticercotic patients may prove useful in monitoring therapeutic attacks on the parasite.

Mitochondrial H+-ATPase activation by an amine oxide detergent

Lauryl dimethylamine oxide activates ATP hydrolysis by the mitochondrial H+-ATPase. Activation is observed in systems with a high content of inhibitor protein as described by Pullman and Monroy (Pullman, M.E., and Monroy, G.C. (1963) J. Biol. Chem. 238, 3762-3769), i.e. Mg-ATP submitochondrial particles and a Triton X-100-solubilized H+-ATPase from the same particles. Detergent activation of ATP hydrolysis is also present in inhibitor-reconstituted systems, i.e. submitochondrial particles, Triton extracts, and soluble F1-ATPase. In submitochondrial particles depleted of inhibitor protein, lauryl dimethylamine oxide induced a biphasic response which is characterized by a drop-in activity induced by relatively low concentrations of LDAO; at higher concentrations the detergent activates to an extent never greater than the initial activity. In inhibitor protein-depleted oligomycin-sensitive Triton extracts, lauryl dimethylamine oxide stimulates ATP hydrolysis to very high values (30 mumol min-1 mg-1). These findings suggest that in addition to the inhibitor protein ATP hydrolysis is controlled by other subunit interactions.

[Compressive hemopericardium of the right atrium after cardiac surgery]

Between June 1983 and September 1984, 3 patients operated for mitral valve disease presented with acute right heart failure due to right atrial compression. Emergency echocardiography did not show pericardial separation around the ventricles but in the apical 4 chamber view severe right atrial compression by an extracardiac mass was observed. Emergency surgery was performed in all three cases to evacuate a localised haemopericardium despite the absence of pericardial fusion. These cases of acute right ventricular failure underline the importance of multiplying the number of echocardiographic views in order to detect localised pericardial effusion. The diagnosis should be made as soon as possible as clinical deterioration may be rapid despite effusions of small volume. The main differential diagnoses are right atrial thrombosis and acute postoperative pulmonary embolism. In these cases of localised tamponade, the clinical signs are the result of vena caval compression or extrinsic compression of the tricuspid orifice. The preferential localisation of the haemopericardium around the right atrium is difficult to explain. It is probably related to the low pressures in this region. The echocardiographic appearances of this condition have been established allowing reliable diagnosis.

Regulation of the Pi-ATP exchange and hydrolytic reactions in F0-F1 reconstituted liposomes

The regulation of ATP hydrolysis and Pi-ATP exchange reactions by ATP, ADP, Mg2+, and phosphate was studied in liposomes containing F0-F1 obtained from bovine heart submitochondrial particles by solubilization with lauryl dimethylamino oxide as described previously (Dreyfus, G., Celis, H., and Ramirez, J. (1984) Anal. Biochem. 142, 215-220). A simultaneous analysis of ATP hydrolysis and the Pi-ATP exchange reactions showed that the ratio of hydrolysis/exchange is close to one when the ATP concentration is in the lower micromolar range. In this preparation ADP stimulates the Pi-ATP exchange reaction and depresses ATP hydrolysis. The exchange reaction is almost abolished when ADP is removed from the medium by an ATP-regenerating system. Mg2+ in millimolar concentrations stimulates Pi-ATP exchange, and at the same time decreases ATP hydrolysis; accordingly, the hydrolysis/exchange ratio depends on the concentration of Mg2+. Inorganic phosphate also controls this ratio, a lower ratio being observed at high phosphate concentrations. The Pi-ATP exchange reaction, but not ATP hydrolysis, depends on the concentration of medium phosphate. These results indicate that the kinetic characteristics of this F0-F1 preparation are modified by Mg2+, ATP, and phosphate.

Reversibility of muscular ischemia: a histochemical quantification by the nitroblue tetrazolium (NBT) test

The degree of muscular ischemia and its reversibility can be quantified in the early stages. This histochemical enzymatic study utilized Nitroblue tetrazolium (NBT) which when reduced by tissue dehydrogenase produces a blue pigment: "formazan." Seventy Wistar rats were subjected to transient hindlimb ischemia by means of a tourniquet for 3, 6, 9, 12, 15 and 18 hours, followed by reperfusion. Microsurgical muscle biopsies were obtained in each rat at 1 and 12 hours, and 3, 7, 14 days after reperfusion. Time increased in muscle staining demonstrated a succino-dehydrogenase deficit confirmed by clinical and histopathological follow-up. NBT staining time was 2 minutes (+/- 8 sec.) in the control group, between 2 and 6 minutes in the reversible ischemia group (rats with 3 and 6 hours of tourniquet), and more than 9 minutes (+/- 14 sec.) in the irreversible ischemia group (animals with more than 9 hours of tourniquet). In vascular surgery and in limb reimplantation this protocol is a practical method of evaluating cytoplasmic enzymatic activity and the status of myofibrillar oxidation in the early phases of ischemic injury, before histologic changes are clearly delineated.

Isolation of the mitochondrial F1-F0 adenosine triphosphatase by Sepharose-hexylammonium chromatography: properties and reconstitution in liposomes

Lauryl dimethylamino oxide, a zwitterionic detergent, was employed to solubilize the H+ ATPase from beef heart mitochondria. A simple preparation procedure has been devised to obtain F1-F0 based on a method described to purify F1 ATPase (M. Tuena de Gómez-Puyou and A. Gómez-Puyou, 1977, Arch. Biochem. Biophys. 182, 82-86) which consists of the selective adsorption of F1 to Sepharose-hexylammonium beads. The preparation showed approximately 18 bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis; 5 correspond to F1 subunits and the rest probably to the stalk and hydrophobic sector F0. The binding of [14C]dicyclohexylcarbodiimide to a low-molecular-weight component of this preparation was demonstrated. The F1-F0 complex was reconstituted into phospholipid vesicles which displayed ATP-Pi exchange and ATP-dependent 9-aminoacridine fluorescence quenching, both sensitive to proton channel inhibitors.

The epsilon subunit as an ATPase inhibitor of the F1-ATPase in Escherichia coli

The isolation of protein ATPase inhibitor was attempted directly from Escherichia coli membrane extracts to examine the possible presence of a Pullman-Monroy-type inhibitor [M. E. Pullman and G. C. Monroy (1963) J. Biol. Chem. 238, 3762-3769] distinct from the epsilon subunit of E. coli ATPase. Purification to homogeneity was achieved in a sequence of steps involving trichloracetic acid precipitation, DEAE-cellulose, Sephadex G75 chromatography, and a terminal isoelectric focusing step. An inhibitory protein was obtained and was identified by its physicochemical and inhibitory properties as the epsilon subunit of E. coli ATPase. The other inhibitory fraction observed in the purification procedure consisted of aggregated epsilon subunits.

Low molecular weight (LMW) heparin derivatives in experimental extra-corporeal circulation (ECC)

Low molecular weight (LMW) heparin has been shown to prevent experimental venous thrombosis. In order to investigate its biological action and its potential use in open heart surgery, we have conducted an experimental study using extracorporeal circulation (ECC) in sheep as an experimental model. 18 sheep were randomly selected to receive either LMW heparin (2 mg/kg), high dose heparin (HD; 160 U/kg), or low dose heparin (LD; 60 U/kg). The HD heparin yielded the same circulating anti-activated factor X (anti-Xa) activities as the LMW heparin and the LD heparin yielded the same anti-thrombin activity. LMW heparin and HD heparin were both effective in preventing blood clotting in the ECC circuit, demonstrating the antithrombotic activity of the LMW heparin. Clotting in the circuit was observed following LD heparin administration showing that the efficacy of LMW heparin does not only rely upon its weak anti-activated partial thromboplastin time (APTT) and anti-thrombin activity. Fibrinogen, fibrinogen degradation products (FDP), factor V (FV), platelet count, antithrombin III (AT III), fast acting antiplasmin (AP) were evaluated during and after ECC. The defects in hemostasis were similar in the three groups. Conclusions were: (1) heparin chain depolymerization diminishes the anti-APTT activity without altering the anti-thrombotic property; (2) LMW heparin is an effective alternative to heparin in cardiac surgery; (3) the absence of postoperative circulating anti-APTT activity might be associated with a reduced incidence of hemorrhagic complication, but we were not able to demonstrate it.

Regulation of the synthesis and hydrolysis of ATP by mitochondrial ATPase. Role of the natural ATPase inhibitor protein

The action of the natural ATPase inhibitor protein of Pullman and Monroy (Pullman, M. E., and Monroy, G. C. (1963) J. Biol. Chem. 238, 3762-3769) on the mechanisms of energy conservation of heart mitochondria has been explored. The synthesis and hydrolysis of ATP and the Pi-ATP exchange reaction were studied in submitochondrial particles that possess the ATPase-inhibitor protein complex in two distinguishable states. In addition to their different rates of hydrolysis, the two states of the complex have been identified from their different accessibility to antibodies directed against the inhibitor protein, and from the different action of antibodies and trypsin on the ATPase activity of the two types of particles studied. The steady state rates of hydrolysis and of the Pi-ATP exchange reaction of the particles are determined by the state in which the ATPase-inhibitor complex exists. Apparently by modifying the rate of one of the steps involved in the catalytic reaction of the ATPase, the inhibitor protein determines the extent to which the enzyme is able to catalyze ATP hydrolysis and the Pi-ATP exchange reaction. This action of the inhibitor protein also reflects the rate at which the particles carry out oxidative phosphorylation.

[Surgery of recurrent aortic dissection. Apropos of 6 cases]

The authors report a series of 6 cases of recurrent dissection, 4 of which were treated surgically, out of a total of 64 acute dissections of the aorta referred to the CMC Foch, between January 1969 and October 1981. Three types of recurrent dissection were identified: --"de novo" recurrent dissection: a new dissection occurring in part of the aorta previously unaffected with a new intimal tear; --recurrent dissection due to extension of the previous dissection; --"in situ" recurrent dissection. Surgery is the treatment of choice because of the poor prognosis. Extensive resection (sometimes carried out in several stages) and deep hypothermia are valuable techniques when part of the aorta giving off arteries to vital organs has to be replaced. The use of GRF biological glue in the treatment of the original acute dissection has been a significant advance in the prophylaxis of recurrent dissection as it ensures better repair of the distal false lumen (27% persistent false lumens). With respect to an extensive replacement of the dissected vessel, the authors advise operation in several stages, especially in young subjects with Marfan's syndrome who are at high risk of recurrent dissection. All cases of acute dissection of the aorta, operated or not, should be followed up indefinitely with clinical and radiological examination, completed, when necessary, by an angioscan and an aortography.