David Lagunoff

The Importance of Biventricular Failure in Patients with Postoperative Cardiogenic Shock

To evaluate the importance of severe biventricular failure in patients with postcardiotomy ventricular failure, we analyzed the data from 30 patients treated with ventricular assist devices (VADs) over a five-year period. All patients had profound postoperative ventricular failure refractory to drugs and an intraaortic balloon (IAB). Evaluation of preoperative ventricular function did not allow prediction of which patients would require VADs. However, the development of perioperative myocardial infarction was an important determinant of the need for postoperative support with a VAD. Twenty patients received only a left VAD (LVAD). Four of them had isolated left ventricular failure; 3 were weaned, and 2 survived. None of the 16 patients with biventricular failure who received only an LVAD were weaned. Ten other patients with biventricular failure received biventricular support, either with a right VAD and IAB, or with two VADs. Of these 10 patients, 5 were weaned and 3 survived. Considering all 26 patients with biventricular failure, those receiving biventricular mechanical support (10) had a better chance (p less than 0.025) of being weaned (5/10) and surviving (3/10) than those who received only an LVAD (0/16). We conclude that biventricular failure is common in patients with postcardiotomy ventricular failure and is often the result of perioperative infarction. While patients with isolated left ventricular failure did well with an LVAD only, those with biventricular failure required biventricular mechanical support for survival.

Experience with the pierce-Donachy ventricular assist device in postcardiotomy patients with cardiogenic shock

In order to assess the current status of ventricular assist device (VAD) support of patients with postcardiotomy ventricular failure, we evaluated the data from 17 patients treated over a 2-year period with a Pierce-Donachy paracorporeal pneumatic sac-type VAD using atrial cannulation and asynchronous pumping. All patients had severe ventricular failure refractory to intra-aortic balloon (IAB) and drug therapy. The effects of the VAD on left ventricular function were evaluated by nuclear ventriculography and hemodynamic measurements during brief pump on/pump off periods. Eight patients received only left VADs, 5 received right VADs and IAB, and 4 received 2 VADs. All patients were weaned from cardiopulmonary bypass with VAD flows ranging from 1.55 to 2.78 L/min per m2.Eight patients died of bleeding, biventricular failure, or multiple organ failure without improvement in cardiac function. However, 9 patients (53%) had improved cardiac function, 8 were weaned from the VAD, and 7 (41%) were discharged. Five of the last 6 patients survived. Two patients with isolated left ventricular failure survived with left VAD alone. However, of 15 patients with biventricular failure, 5 of 9 receiving biventricular assistance were weaned, while only 1 of 6 receiving left VAD alone was weaned. Although activation of the left VAD decreased left ventricular ejection fraction, left atrial pressure, and left ventricular volume, it concomitantly increased left ventricular afterload. The Pierce-Donachy VAD provided salvage of patients with severe ventricular failure after cardiac operations. The majority of patients had biventricular failure, which was best treated with biventricular mechanical support. Although the VAD reduced left ventricular preload, ejection fraction decreased as afterload increased, suggesting that asynchronous left atrial pumping does not unload the left ventricle.RésuméDe façon à définir lutilisation actuelle de la pompe dassistance ventriculaire chez les malades ayant une défaillance ventriculaire après chirurgie cardiaque, nous avons analysé les données de 17 malades traités pendant une période de plus de 2 ans par assistance ventriculaire avec une pompe para-corporelle Pierce-Donachy à type de sac pneumatique avec canulation auriculaire et pompage asynchrone. Tous les malades avaient une défaillance ventriculaire sévère ne répondant pas au ballon de contre-pulsion intra-aortique et aux drogues inotropes. Leffet de lassistance ventriculaire sur la fonction ventriculaire gauche fut apprécié par des ventriculographies isotopiques et par des mesures hémodynamiques pendant des brèves périodes darrêt de la pompe dassistance. Huit malades ont eu une assistance ventriculaire gauche isolée, 5 ont une assistance ventriculaire droite et un ballon de contre-pulsion diastolique et 4 ont eu deux pompes dassistance ventriculaire.Les 17 malades ont été sevrés de la circulation extra-corporelle avec un index dassistance ventriculaire allant de 1,55 à 2,78 L/mn/m2. Huit malades sont décédés dhémorragie, de défaillance bi-ventriculaire ou de défaillance polyviscérale sans amélioration de la fonction cardiaque, 8 ont été sevrés de la pompe dassistance, et 7 (41%) sont sortis de lhôpital. Cinq des 6 derniers malades ont survécu. Deux malades ayant eu une défaillance ventriculaire gauche isolée, ont survécu grâce à une assistance ventriculaire gauche sélective. Des 15 malades ayant eu une défaillance bi-ventriculaire, 5 sur 9 qui ont eu une assistance bi-ventriculaire ont pu être sevrés, alors que seulement un des 6 qui ont eu une assistance ventriculaire gauche isolée a pu être sevré. Bien que leffet de lassistance ventriculaire soit de diminuer la fraction déjection ventriculaire gauche, la pression auriculaire gauche et le volume ventriculaire gauche, cette assistance a pour effet concomitant daccroitre la précharge du ventricule gauche.Lassistance ventriculaire de Pierce-Donachy permet de sauver des malades ayant des défaillances ventriculaires sévères après chirurgie cardiaque. La majorité de ces malades qui avaient des défaillances bi-ventriculaires, ont été traités au mieux par un support mécanique bi-ventriculaire. Bien que lassistance ventriculaire diminue la précharge du ventricule gauche, la fraction déjection diminue autant que la post-charge augmente, ce qui laisse supposer quune assistance auriculaire gauche asynchrone ne décharge pas le ventricule gauche.ResumenCon el objeto de determinar el estado actual del soporte de pacientes con falla ventricular postcardiotomía mediante asistencia mecánica ventricular (AMV), procedimos a evaluar los datos sobre 17 pacientes tratados en un período de 2 años con AMV por el sistema de saco neumático paracorporéo Pierce-Donachi utilizando canulación atrial y bombeo asíncrono. Todos los pacientes exhibían severa falla ventricular refractaria al balón intraaórtico (BIA) y a terapia con drogas. Los efectos de la AMV sobre el ventrículo izquierdo fueron evaluados mediante ventriculografía nuclear y mediciones hemodinámicas durante breves períodos de interrupción de la bomba. Ocho pacientes recibieron sólo AMV izquierda, cinco recibieron AMV derecha y BIA, y cuatro recibieron dos AMVs.Todos los pacientes fueron desahijados de la perfusión cardiopulmonar extracorpórea con flujos de AMV fluctuantes entre 1.55 y 2.78 L/min/M2. Ocho pacientes murieron por hemorragia, falla biventricular o falla orgánica múltiple sin mejoría en la función cardíaca. Sinembargo, nueve pacientes (53%) mostraron mejor función cardíaca, ocho fueron desahijados de la AMV y siete (41%) fueron dados de alta del hospital. Cinco de los últimos seis pacientes han sobrevivido. Dos pacientes con falla ventricular izquierda aislada sobrevivieron después de AMV izquierda solamente. Sin embargo, de 15 pacientes con falla biventricular, cinco de nueve que recibieron asistencia biventricular fueron desahijados, en tanto que apenas uno de seis que recibieron AV, izquierda solamente pudo ser desahijado. Aunque la activación de la AMV izquierda disminuyó la fracción de eyección del ventrículo izquierdo, la presión en la aurícula izquierda y el volumen ventricular izquierdo, concomitantemente incrementó la postcarga ventricular izquierda.El sistema Pierce-Donachy de AMV permitió el salvamento de pacientes con severa falla ventricular después de operaciones cardiacas. La mayoría de los pacientes tenían falla biventricular, la cual fué tratada en forma óptima con soporte mecánico biventricular. Aun cuando la AMV redujo la precarga ventricular izquierda, la fracción de eyección disminuyó en la medida que se redujo la postcarga, lo cual sugiere que el bombeo atrial izquierdo asíncrono no descomprime en forma efectiva al ventrículo izquierdo y que éste en realidad queda sujeto a una mayor impedancia ventricular izquierda. A pesar de ello, también se observa una significativa disminución en el volumen diastólico y en la presión de la aurícula izquierda, lo cual resulta en una reducción de la precarga concomitante con el aumento en la postcarga. La reducción en el volumen diastólico probablemente explica la menor fracción de eyección durante el bombeo de AMV. Este efecto, más la reducción teórica en la tensión de la pared ventricular resultante de un menor volumen del ventrículo izquierdo, puede reducir el consumo miocárdico de oxígeno.

Phosphatidylcholine metabolism in endothelial cells: Evidence for phospholipase A and a novel Ca2+-independent phospholipase C

The metabolism of phosphatidylcholine (PC) was investigated in sonicated suspensions of bovine pulmonary artery endothelial cells and in subcellular fractions using two PC substrates: 1-oleoyl-2-[3H]oleoyl-sn-glycero-3-phosphocholine and 1,2-dipalmitoyl-sn-glycero-3-phospho[14C]choline. When these substrates were incubated with the whole cell sonicate at pH 7.5, all of the metabolized 3H label was recovered in [3H]oleic acid (95%) and [3H]diacylglycerol (5%). All of the 14C label was identified in [14C]lysoPC (92%) and [14C]phosphocholine (8%). These data indicated that PC was metabolized via phospholipase(s) A and phospholipase C. Substantial diacylglycerol lipase activity was identified in the cell sonicate. Production of similar proportions of diacylglycerol and phosphocholine and the low relative activity of phospholipase C compared to phospholipase A indicated that the phospholipase C-diacylglycerol lipase pathway contributed little to fatty acid release from the sn-2 position of PC. Neither phospholipase A nor phospholipase C required Ca2+. The pH profiles and subcellular fractionation experiments indicated the presence of multiple forms of phospholipase A, but phospholipase C activity displayed a single pH optimum at 7.5 and was located exclusively in the particulate fraction. The two enzyme activities demonstrated differential sensitivities to inhibition by p-bromophenacylbromide, phenylmethanesulfonyl fluoride and quinacrine. Each of these agents inhibited phospholipase A, whereas phospholipase C was inhibited only by p-bromophenacylbromide. The unique characteristics observed for phospholipase C activity towards PC indicated the existence of a novel enzyme that may play an important role in lipid metabolism in endothelial cells.

Isolation of rat mast cell granules with intact membranes

Abstract A method for controlled sonication of isolated rat peritoneal mast cells and separation of the membrane-bound secretory granules on a self-generating density gradient of Percoll (polyvinyl-pyrrolidone-coated silica gel particles) is described. Ruthenium red, which binds exclusively to the matrix of the membrane-free granules, proved to be an excellent agent for the quantitative assessment of the state of the perigranular membranes in the various preparations. The percentage of intact granules, as observed in the electron microscope, increased from 49% in the primary granule pellet to 75% after separation on Percoll gradient, whereas the corresponding figures as revealed by the ruthenium red method were 69 and 93% respectively. The observed discrepancies were due to difficulties involved in sampling the granule pellets for electron microscopy.

Recovery of rat mast cells after secretion: A morphometric study☆

Granule reconstitution in rat peritoneal mast cells following massive secretion was studied by morphometric techniques. Immediately following secretion, the earliest identifiable mast cells showed a substantial decrease in cell volume associated with granule loss. Cell volume then increased almost to the original level over a period of a month. The size of the Golgi apparatus increased markedly in the week following secretion and then returned to its original size. The total volume of granules increased slowly after the secretory depletion and by 34 days had not returned to the original value although the number of granules had recovered fully. The reconstitution of mast cells after secretion is a prolonged process with several phases resulting in mast cells of varying appearance and content. This heterogeneity generated by reconstitution post secretion must be considered in studies of populations of mast cells in vivo.

Evidence for control of mast cell granule protease in situ by low pH

The second order rate constant, k2, for the inhibition of mast cell protease I by phenylmethanesulfonyl fluoride (PMSF) is lower for intact mast cells and isolated granules with intact membranes than for granules stripped of their membranes and suspended in medium at pH 7.1. In order to test the hypothesis that the decreased activity of the protease in intact granules is attributable to low pH, two agents capable of lowering pH in intracellular compartments similar to mast cell granules were tested. Ammonium chloride increased k2 of the protease in isolated granules with intact membranes and mast cells and wash out of the salt partially reversed this effect. Treatment of cells with nigericin also substantially increased the rate of protease inactivation by PMSF. These results are consistent with the proposal that the observed k2 is determined in whole or part by a low pH of the granule in situ or isolated with intact membranes. If the low k2 in situ is solely dependent on low pH, then the rate of protease inhibition can be utilized as an endogenous probe of granule pH. On this basis we have estimated the pH of the intracellular granule as 5.2 and that of the isolated granule with its membrane intact as 6.0. The value for the pH of granules in situ is lower than that previously estimated, and we have considered possible bases for this discrepancy.

Aluminum-Containing Emboli in Infants Treated with Extracorporeal Membrane Oxygenation

We found fibrin thrombi or thromboemboli at autopsy in 22 of 23 infants with respiratory failure who had been treated with venoarterial extracorporeal membrane oxygenation (ECMO). In addition, distinctive basophilic aluminum-containing emboli were found in 12 of the infants; the distribution of these emboli was similar to that of the thromboemboli, except that an aluminum-containing embolus was found in a lung in only 1 infant. Sixteen infants had pulmonary thrombi or thromboemboli. We also found friable aluminum-containing concretions adhering loosely to the mixing rods of heat exchangers that had been used to warm the blood flowing through the ECMO circuit; such concretions were not present on unused mixing rods. We propose that these aluminum-containing concretions developed as the silicone coating of the heat exchanger wore away and aluminum metal was exposed to warm, oxygenated blood and that fragments of aluminum-containing concretions formed emboli. This hypothesis is supported by the fact that aluminum-containing emboli were generally not present in the lungs, which are bypassed by ECMO. Although infarcts were found in 16 of the 23 infants, we cannot be certain whether any of the infarcts were caused by the aluminum-containing emboli.

Secretion from rat basophilic leukaemia cells induced by calcium ionophores Effect of pH and metabolic inhibition

Previous experiments on the functional properties of rat basophilic leukaemia cells showed a major anomaly when compared to normal mast cells: though IgE-mediated secretion was dependent on external Ca2+ with both types of cells, substantial non-cytotoxic release with ionophore A23187 could be demonstrated with the normal cells but not with the tumour cells. We now show that when the pH of the incubation medium is increased to 8 it is possible to obtain excellent Ca-dependent, non-cytotoxic secretion from tumour basophils with the ionophores A23187 and ionomycin. These results provide further evidence that secretion from the tumour cells occurs via a mechanism similar to that used by normal mast cells and basophils. Experiments with metabolically inhibited tumour cells suggest that their unusual sensitivity to the cytotoxic effects of Ca2+ ionophores may be related to their ability to sequester intracellular calcium. Changes in the conditions of cell culture appeared to produce substantial and at least partially reversible changes in responsiveness to IgE-mediated triggering and ionophores.

Rat mast cell tryptase

Rat mast cell tryptase is located largely if not totally in the cells secretory granules. When the active site reagent [3H]diisopropyl fluorophosphate was used to label tryptase and chymase simultaneously, the ratio of tryptase:chymase active sites was determined to be 0.05. In comparison to chymase and tryptase in other species and chymase in the rat, rat tryptase is poorly bound to the granule matrix as evidenced by (1) its release parallel to histamine on induction of secretion and (2) its appearance in the supernatant when isolated granules were stripped of their membranes with hypotonic medium. Tryptase on release from the granule is moderately stable at a pH of 5.0 but unstable at pH 7.5, the pH that the enzyme encounters on secretion from the cell. These several properties indicate that the role of rat mast cell tryptase extracellularly is likely to differ greatly from that of chymase.

Histidine transport by isolated rat peritoneal mast cells

Abstract Kinetic constants for the transport of [3H]histidine into isolated rat peritoneal mast cells were determined. The value of Km for histidine transport was 44.0 μM; the value of Vmax under the same conditions was 18.9 pinoles · min− · (106 cells)−1. These parameters did not change in value after the addition of exogenous histamine. The uptake of histidine and its decarboxylation to histamine were relatively rapid processes compared to the transfer of the newly formed histamine into mast cell granules, so that nascent histaramine appeared transiently in the cytoplasm. Amino-acid competition experiments support the assignment of L system transport for the bulk of histidine uptake by mast cells. Metabolic inhibitors that deplete cellular ATP did not inhibit the uptake process.