Measurement of platelet microparticles during cardiopulmonary bypass by means of captured ELISA for GPIIb/IIIa.

A captured enzyme-linked immunosorbent assay (ELISA) using the disintegrin, kistrin, is described and used to measure platelet microparticles (PMP) generated during open heart surgery. This ELISA detects 75 ng/ml of glycoprotein IIb/IIIa (GPIIa/IIIa) in solution and is more sensitive and less variable than flow cytometry and radioimmunoassay. By ELISA, mean values of GPIIb/IIIa in PMP are 14.2 +/- 7.9 microg/ml for outdated platelets and 0.28 +/- 0.1 microg/ml in fresh blood from healthy donors. Normal washed platelets (10(8)) contain 8.8 microg of GPIIb/IIIa. In 12 cardiac surgical patients, PMP measured by ELISA significantly increased (p = 0.039) to 0.58 +/- 0.3 microg/ml at the end of cardiopulmonary bypass, but the increase measured by flow cytometry (1207 to 1447 events in PMP gate) was not significant. Neither heparin nor protamine alter PMP. After cardiopulmonary bypass, PMP concentrations return to baseline values before protamine is given. Concentrations of PMP in pericardial blood are greater than in simultaneous perfusate. This ELISA is more sensitive and accurate than alternate methods for measuring PMP and shows the PMP production and rapid clearance during open cardiac surgery.

Glycoprotein IIb/IIIa receptor antagonist tirofiban inhibits thrombin generation during cardiopulmonary bypass in baboons.

Platelets play a major role in coagulation mechanisms and anti-GPIIb-IIIa antibodies inhibit tissue-factor induced thrombin generation in in vitro studies. Tirofiban, a nonpeptide selective glycoprotein (GP) IIb/IIIa antagonist, preserves platelet number and function during cardiopulmonary bypass (CPB) in baboons. We tested the hypothesis that platelet inhibition by tirofiban inhibits thrombin generation in vivo. Four groups of baboons (n = 7-12) were perfused for 60 min; all groups received heparin (300 units/kg). The controls received only heparin. The low dose (0.1 microg/kg/min) and high dose (0.3 microg/kg/min) infusion groups received tirofiban for 60 min before and 60 min during CPB. The bolus plus low dose infusion group received a 15 microg/kg bolus before starting CPB and a low dose infusion (0.1 mg/kg/min) only during CPB. At end of CPB, compared to control group (2.99+/-0.36 nM), prothrombin fragment F1.2 levels were lower (p<0.05) in low dose infusion group (1.65+/-0.14 nM, mean +/- SE) and high dose infusion group (1.71+/-0.19 nM), but not bolus plus infusion group (2.69+/-0.49 nM); they remained significantly lower after protamine administration. At end of CPB, thrombin-antithrombin complex levels were lower in high dose infusion group (40.0+/-11.2 ng/ml, p<0.05) compared to control group (76.2+/-7.3 ng/ml). These studies indicate that tirofiban inhibits not only platelet aggregation but also thrombin generation in vivo during CPB, and that this effect is demonstrable even in the presence of intense heparin anticoagulation. They underscore the important inhibitory effect of GPIIb-IIIa antagonists on thrombin generation.

Alpha 1-antitrypsin Pittsburgh (Met358-->Arg) inhibits the contact pathway of intrinsic coagulation and alters the release of human neutrophil elastase during simulated extracorporeal circulation.

Cardiopulmonary bypass prolongs bleeding time, increases postoperative blood loss, and triggers activation of plasma proteolytic enzyme systems and blood cells referred to as the "whole body inflammatory response". Contact of blood with synthetic surfaces leads to qualitative and quantitative alterations in platelets, neutrophils, contact and complement systems. Contact and complement pathway proteins both induce neutrophil activation. alpha 1-antitrypsin Pittsburgh (Met358-->Arg), a mutant of alpha 1-antitrypsin, is a potent inhibitor of plasma kallikrein and thrombin. We investigated whether this recombinant mutant protein inhibited platelet activation, as well as contact and/or complement-induced neutrophil activation during simulated extracorporeal circulation. Arg358 alpha 1-antitrypsin did not prevent the 34% drop in platelet count at 5 min of recirculation, did not block the 50% decrease in ADP-induced platelet aggregation at 120 min of recirculation, nor inhibit the release of 6.06 +/- 1.07 micrograms/ml beta-thromboglobulin at 120 min of recirculation suggesting that the inhibitor had little effect on platelet activation. However, Arg358 alpha 1-antitrypsin totally blocked kallikrein-C1-inhibitor complex formation but not C1-C1-inhibitor complex formation. Most importantly, Arg358 alpha 1-antitrypsin decreased the release of 1.11 +/- 0.16 micrograms/ml human neutrophil elastase by 43%. The attenuation of neutrophil activation in the absence of an effect on complement activation via the classical pathway, supports the concept that kallikrein is a major mediator of neutrophil degranulation during cardiopulmonary bypass.

Nafamostat mesilate, a broad spectrum protease inhibitor, modulates platelet, neutrophil and contact activation in simulated extracorporeal circulation.

Activation of humoral and cellular participants in inflammation enhances the risk of postoperative bleeding and multiple organ damage in cardiopulmonary bypass (CPB). We now compare the effects of heparin alone in combination with nafamostat mesilate (NM), a protease inhibitor with specificity of trypsin-like enzymes, in an extracorporeal circuit which simulates CPB. NM significantly inhibits the release of platelet beta-thromboglobulin (beta TG) at 60 and 120 min. Platelet counts do not differ. ADP-induced aggregation decreases in circuits with NM, which is due to a direct effect of NM on platelet function. NM prevents any significant release of neutrophil elastase; at 120 min, plasma elastase-alpha 1-antitrypsin complex is 0.16 micrograms/ml in the NM group and 1.24 micrograms/ml in the control group. NM completely inhibits formation of complexes of C1 inhibitor with kallikrein and FXIIa. NM does not alter markers of complement activation (C1-C1-inhibitor complex and C5b-9), or indicators of thrombin formation (F1.2). However, at 120 min, thrombin activity as measured by release of fibrinopeptide A is significantly decreased. The data indicate that complement activation during CPB correlates poorly with neutrophil activation and that either kallikrein or FXIIa or both may be more important agonists. The ability of NM to inhibit two important contact system proteins and platelet and neutrophil release raises the possibility of suppressing the inflammatory response during clinical CPB.

Interaction of leukocytes with platelet microparticles derived from outdated platelet concentrates.

Platelet microparticles (PMP) were isolated from outdated platelets by a combination of differential centrifugation and gel filtration, and the concentration of PMP was expressed in the equivalent of GPIIb/IIIa complex measured by captured ELISA. PMP bound to isolated neutrophils and macrophages in a dose-dependent manner, but they did not bind to lymphocytes. Incubation of PMP with neutrophils did not activate these cells as measured by up-regulation of Mac-1, release of human granulocyte elastase, and calcium mobilization. Incubation of PMP with macrophages did not enhance IL-8 production and the oxygen burst but slightly and significantly increased production of MCP-1. After 10 min incubation of PMP with macrophages, an increase of GPIIb/IIIa antigen was observed suggesting that PMP may be endocytosed by macrophages. In conclusion, PMP bind to leukocytes, but, in contrast to activated platelets, do not play a significant role in leukocyte activation.

Thrombin and human plasma kallikrein inhibition during simulated extracorporeal circulation block platelet and neutrophil activation.

Cardiopulmonary bypass causes hemorrhagic complications, and initiates a chemical and cellular inflammatory response. Contact of blood with synthetic surfaces leads to qualitative and quantitative alterations in platelets, neutrophils, complement, and contact systems. Despite the fact that cardiopulmonary bypass is carried out in the presence of high doses of heparin, there is significant activation of both platelets and neutrophils. Thrombin is protected on cell and fibrin surfaces from antithrombin, even in the presence of high doses of heparin (approximately 5 U/ml). We therefore studied the effect of a small (Mr = 497), highly effective (Ki = 41 pM), reversible tripeptide inhibitor of thrombin, DUP 714 (1 microM), in a well characterized model of simulated extracorporeal circulation. In the absence of DUP 714, platelet counts decreased by 75% 5 min after the start of extracorporeal bypass and increased to 48% at 120 min of recirculation. DUP 714 significantly preserved platelet counts, decreased plasma levels of platelet beta-thromboglobulin levels, but did not prevent a decrease in sensitivity of platelets to adenosine diphosphate. Kallikrein-C1-inhibitor and C1-C1-inhibitor complexes increased progressively from 0.32 U/ml to 0.67 U/ml and from 4.45 U/ml to 7.25 U/ml, respectively, during 120 min of recirculation without DUP 714. Addition of DUP 714 significantly inhibited kallikrein-C1-inhibitor complex formation but did not affect C1-C1-inhibitor complexes. In the absence of DUP 714, human neutrophil elastase levels rose from a baseline of 0.01 +/- 0.00 microg/ml to 1.18 +/- 0.21 microg/ml during 120 min of recirculation. Human neutrophil elastase release at 120 min was significantly inhibited in the presence of DUP 714 to 37% of the value with heparin alone. These results indicated that addition of this novel thrombin (and kallikrein) inhibitor to heparin preserved platelet counts, decreased platelet secretion, and provided the additional benefit of partially blocking neutrophil activation during simulated extracorporeal circulation.

Operation for acute postinfarction mitral insufficiency and cardiogenic shock.

Since 1973, 11 patients have had emergency valve replacement for severe mitral insufficiency and cardiogenic shock within 1 month (mean 10.0 days) of acute myocardial infarction. Mean age was 60 years (range 44 to 71 years). Nine infarcts affected the inferior wall, one patient had a prior myocardial infarction, and only two patients had a history of cardiac symptoms. Ten patients had pulmonary edema, five were oliguric (less than 0.5 ml/kg/hr for 12 hours), four required endotracheal intubation, nine required preoperative intra-aortic balloon support, and three had had a cardiac arrest. Preoperative cardiac index averaged 1.7 L/m2/min even with pharmacologic and circulatory support. Eight patients had cardiac catheterization and nine had echocardiograms. Left ventricular ejection fraction varied from 23% to 83% (mean 51%) and was not prognostic. Five patients had papillary muscle rupture and six patients had papillary muscle dysfunction. The mitral valve was replaced with a mechanical prosthesis in all patients. Five had simultaneous coronary artery bypass grafts. Three of five patients with papillary muscle rupture and two of six with papillary muscle dysfunction survived hospitalization. Two patients could not be weaned from cardiopulmonary bypass, two patients died within 24 hours of low cardiac output, and two patients died 3 weeks postoperatively of acute tubular necrosis and sepsis following prolonged preoperative cardiogenic shock. The interval from onset of shock to operative therapy averaged 1.7 days for survivors versus 9.3 days for nonsurvivors. Although the amount of viable left ventricular mass cannot be measured preoperatively, we recommend early operation, before other organ systems fail, for patients having severe mitral insufficiency and cardiogenic shock within 30 days of acute myocardial infarction.

Simultaneous implantation of St. Jude Medical aortic and mitral prostheses.

Since January 1980, 92 consecutive patients received St. Jude Medical aortic and mitral prostheses simultaneously. Mean age was 57.6 years (standard deviation 12.4); 14 were 70 years or older. Twenty-three had a previous cardiac operation and 22 had additional procedures performed at the time of double valve replacement. Before the operation 62% of the patients were in New York Heart Association functional class III and 29% were in class IV or required emergency operation. There were six (6.5%) deaths within 30 days. None of the hospital deaths were valve related; all occurred in patients who had additional risk concerns. Follow-up is 100% complete and ranges from 2 to 80 months, totaling 242 patient-years (mean 33.8 months). All except four hospital survivors reached class I or II and 40 patients (47%) remain asymptomatic. The actuarial survival rates are 82% at 1 year, 70% at 3 years, and 60% at 5 years. Causes of late death include heart failure (10), sudden, unexplained death (five), reoperation for coronary artery disease (one), noncardiac (four), and valve related (five). The linearized rate of fatal valve-related events is 2.1% pt-yr. A total of 22 valve-related complications (including five fatal) occurred is 18 patients, for a linearized rate or incidence of 9.1%/pt-yr. Eleven thromboembolic episodes (rate 4.6%/pt-yr) occurred in nine patients; three of these (1.2%/pt-yr) were fatal. Thromboembolic and bleeding complications represented 64% of all valve-related complications. Four patients had six episodes of prosthetic valve endocarditis (incidence 2.5%/pt-yr), of which one (incidence 0.4%/pt-yr) was fatal. Paravalvular leak contributed to the fifth valve-related death. At 5 years, 83% of patients were free of thromboembolic complications; 94% were free of anticoagulant-related hemorrhage; and 71% were free of all valve-related complications. There are few comparable data for patients who have had simultaneous replacement of aortic and mitral valves with other mechanical prostheses. The total incidence of valve-related complications for patients with bioprostheses ranges between 3.9%/pt-yr and 10.4%/pt-yr and is similar to the 9.1%/pt-yr observed in the present series. The type of valve-related complication (thromboemboli and bleeding versus valve deterioration) is the principal difference between St. Jude Medical and bioprosthetic valves in patients who require simultaneous replacement of aortic and mitral valves.

Tetracycline pleurodesis during active pulmonary-pleural air leak for prevention of recurrent pneumothorax.

Pleurodesis with a sclerosing agent was attempted in an animal model in which a pneumothorax with an active air leak was created. Adult rabbits had a small left thoracotomy and then a 1-cm controlled cut in the lung surface. Animals served as control, or tetracycline was administered. The chest tube was removed after the air leak stopped. Animals were sacrificed after 20 days. Group A was control rabbits (6); group B had powdered tetracycline placed at thoracotomy; group C, tetracycline solution, 2 ml/kg, 25 mg/ml (4); and group D, tetracycline solution, 1 ml/kg, 50 mg/ml (10). Control rabbits showed few adhesions, and the pleura appeared to be normal by histologic examination. There was a spectrum of results with tetracycline, but with the concentrated tetracycline solution (group D) histologic examination showed uniform pleurodesis and thickening of the pleura. In group D it took no longer for the pulmonary air leak to seal than with the group A (control) rabbits. We conclude that concentrated tetracycline solution is effective in causing pleurodesis even when an active air leak is present. The lung, however, must be kept expanded so that symphysis can occur between the visceral and parietal pleura.

Bar calcification of the mitral anulus. A risk factor in mitral valve operations.

Between Jan. 1, 1979, and Jan. 1, 1986, 72 septuagenarians had open heart operations for disease of the mitral valve. Thirty-two (44%) had additional operative procedures. Overall seven patients (9.7%) died within 30 days of operation. Eleven patients had bar calcification of the posterior mitral annulus as defined by three criteria and 61 did not. No differences between these two groups were present except for hospital mortality. Three of the 11 patients (27.3%) died at or soon after operation of complications resulting from the calcified annular bar. Only four of 61 patients (6.6%) without bar calcification died early. The difference in early mortality between the two groups is significant (p less than 0.05) and identifies the presence of bar calcification of the posterior mitral annulus as an independent risk factor of mitral valve operations in elderly patients.

Unexpected, sustained ventricular tachyarrhythmia after cardiac operations.

Unexpected, sustained ventricular tachyarrhythmia after cardiac operations is differentiated from sustained ventricular tachycardia and ventricular fibrillation from known antecedent causes, such as recent or perioperative myocardial infarction, low cardiac output, preoperative ventricular arrhythmia, sympathomimetic drugs, drug toxicity, and metabolic abnormalities. Sixteen of 2364 patients (0.68%) who underwent heart operations met strict exclusion criteria for unexpected sustained ventricular tachyarrhythmia that occurred 1 hour to 12 days after operation. Recurrent ventricular tachyarrhythmias occurred in 12 patients; three died (21%), despite resuscitation from the initial episode. All patients had significant preoperative left ventricular dysfunction and 14 had ejection fractions below 30%. Fifteen of the 16 patients had monomorphic ventricular tachycardia at the initial episode. Empirically prescribed therapy was not effective in suppressing ventricular tachyarrhythmias inducible by programmed stimulation during postevent electrophysiologic studies in 10 of the 13 survivors. Inducibility was eventually prevented by drugs in nine patients, three patients received automatic implantable cardiac defibrillators, and one patient underwent successful catheter ablation of ventricular tachycardia. No patient died of recurrent ventricular tachyarrhythmias during the follow-up of 8 to 55 (mean 29) months after hospital discharge.

Aortopulmonary window and aortic isthmic hypoplasia. Operative management in newborn infants.

Aortopulmonary window with aortic isthmic hypoplasia is an unusual combination of congenital heart lesions that usually causes severe heart failure, poor systemic perfusion, and death shortly after birth. In 21 previously reported cases, survival beyond infancy was uncommon, yet only one neonate survived operation. This report describes three cases of aortopulmonary window and aortic isthmic hypoplasia and a two-stage operative approach that proved successful in both infants in which it was tried. During the first step the isthmic obstruction is relieved, the ductus is ligated, and the aortopulmonary window is plicated via a left thoracotomy. The second stage consists of definitive closure of the aortopulmonary window using the technique of deep perfusion hypothermia.

Massive hemoptysis secondary to pulmonary arteriovenous fistula. Treatment by a catheterization procedure.

Massive pulmonary hemorrhage secondary to an acquired arteriovenous fistula is a rare event associated with high mortality. Cotton wads mounted on steel coils were inserted by percutaneous catheter and successfully occluded a pulmonary arteriovenous fistula in a patient who had massive hemoptysis and contraindications to thoracotomy.

Changes in extravascular lung water during venovenous perfusion.

The accumulation of extravascular lung water was related to changes in plasma colloid osmotic pressure and pulmonary hydrostatic pressures in 12 normal dogs and 13 dogs that had venovenous perfusion for 2 hours at 45 to 70 ml. per kilogram per minute. The venovenous perfusion system included a membrane oxygenator and a roller pump. Net intravascular filtration pressure was calculated from plasma colloid osmotic pressure and pulmonary hydrostic pressures. Rapid accumulation of extravascular lung water occurred in control and bypass animals when net intravascular filtration pressure exceeded zero. At lower filtration pressures, venovenous perfusion did not affect accumulation of extravascular lung water.

Mitral atresia with premature closure of foramen ovale. A rare hemodynamic cause for failure of Blalock-Taussig anastomosis to relieve inadequate pulmonary blood flow.

The clinical, hemodynamic, and surgical findings encountered in the management of a hypoxic male infant with a rare and complex variety of cyanotic congenital heart disease associated with inadequate pulmonary blood flow are described. A poor clinical response to creation of a Blalock-Taussig anastomosis led to the discovery of mitral atresia complicated by premature closure of the foramen ovale and partially relieved by the presence of a levoatriocardinal vein. The subsequent creation of an atrial septal defect enhanced the function of the subclavian artery to pulmonary artery anastomosis and provided palliative relief of hypoxia. Some of the clinical and laboratory findings indicating the presence of additional lesions complicating the picture of a tetralogy of Fallot and requiring additional surgical considerations are discussed. The experience indicates that hemodynamic as well as surgical causes may explain the failure of a systemic artery to pulmonary artery anastomosis to function adequately and should be sought.

Prognosis of pulmonary scar carcinoma.

Eighty-one patients with resectable primary peripheral lung carcinomas were studied to determine the effect of associated scarring on prognosis. Twelve tumors (15%) originated from bronchi. 24 (30%) were associated with scars, and 45 (55%) were not associated with either bronchus or scar (non-scar). Scar carcinomas differed significantly in cell type from bronchogenic and non-scar tumors in that 21 (88%) scar carcinomas were either adenocarcinomas or bronchioloalveolar carcinomas (p less than 0.001). Origin (bronchogenic, scar, non-scar) independent of cell type and tumor stage did not significantly influence survival. Stage of disease independent of cell type or origin affected survival (p less than 0.0001), as did cell type independent of tumor stage or origin (p less than 0.0001). Stage I disease and bronchioloalveolar carcinoma were associated with longer survival, while Stage II or III disease, small cell anaplastic carcinoma, and adenocarcinoma were associated with reduced survival. We conclude that associated scar influences cell type of peripheral lung carcinoma but does not influence patient survival, even among patients with similar cell type and stage of disease.

Flow dynamics of peripheral venous catheters during extracorporeal membrane oxygenation with a centrifugal pump.

Extracorporeal membrane oxygenation uses peripherally placed cannulas and a streamlined circuit without a venous reservoir. This study tests the flow dynamics of venous catheters connected without a reservoir directly to a centrifugal pump. During in vitro testing, a 30 cm segment of collapsible tubing interposed between the reservoir and pump simulates the vein. In five sheep, flow was measured between catheters placed in the right atrium and inferior vena cava from peripheral sites. Catheter tip design (four types) does not affect flow within a simulated vein in vitro. Maximum pump flow is independent of filling pressures (6 to 21 mm Hg) in vitro and in vivo when the catheter tip is in a tank reservoir or the right atrium. However, when the catheter tip is within a collapsible segment or in the inferior vena cava, maximal flow is significantly influenced by filling pressure (6 to 18 mm Hg) and by the ratio of catheter outer diameter to venous diameter. At all filling pressures, maximal flow in vivo is significantly reduced when this ratio is greater than 0.5. During extracorporeal membrane oxygenation, central venous pressure and catheter/vein ratio, not catheter size alone, control flow through peripheral venous catheters.

Cardiovascular perfusion: evolution to allied health profession and status 1986.

The occupation of cardiovascular perfusion has evolved from a technical to a professional status during the past 25 years. The national thoracic surgical organizations, The American Association for Thoracic Surgery and the Society of Thoracic Surgeons, have supported this process of development through participation on various boards and committees of the perfusionist organizations. The rapid growth of cardiac surgical services in the past decade produced concern about the availability of perfusionist manpower. This concern was exacerbated by creation of formal processes for the certification of perfusionists and the accreditation of perfusion educational programs. Today, these issues are largely resolved and cardiovascular perfusion is recognized as an allied health profession.

Loss of platelet fibrinogen receptors during clinical cardiopulmonary bypass.

In 10 patients, cardiopulmonary bypass decreased the number of fibrinogen binding sites from 31,730 +/- 12,802 per platelet to 18,590 +/- 9,644 per platelet. Bypass also decreased the amount of the platelet membrane glycoprotein IIIa, which is part of the fibrinogen receptor complex, from 17.1 +/- 3.6 ng/10(9) platelets to 12.9 +/- 4.7. The fibrinogen binding constant did not change. Platelet sensitivity to adenosine diphosphate did not change; however, template bleeding times increased from 5.2 +/- 1.5 minutes before bypass to 8.5 +/- 2.3 minutes after bypass. Analysis of detergent washings from the perfusion circuit after bypass in five patients indicated that platelet material remains attached to the surface as membrane fragments and degranulated platelets. These data further elucidate the mechanism of platelet loss and dysfunction during cardiopulmonary bypass and highlight the importance of platelet membrane fibrinogen receptors and surface adsorbed fibrinogen in this process.

Left ventricular mechanics of ejecting, postischemic hearts during left ventricular circulatory assistance.

We measured the effects of left ventricular circulatory assistance on ventricular mechanics of ejecting sheep hearts before and after global ischemia. Flows from left atrium to femoral artery ranged between 20 and 100 ml/kg/min during circulatory assistance. In preischemic, ejecting hearts increasing flow through the left ventricular assist device progressively decreased stroke volume, end-diastolic volume, and circumferential systolic wall stress, but only slightly decreased end-systolic volume. In postischemic, ejecting hearts left ventricular assistance progressively and substantially decreased both end-diastolic volume and end-systolic volume; at high flows, end-systolic volume returned to the normal range of preischemic hearts. High flows through the assist device also shifted end-systolic points of pressure-volume loops leftward and increased the stroke work/end-diastolic volume ratio in ejecting postischemic hearts; these observations raise the possibility that left ventricular circulatory assistance acutely improves myocardial contractility of postischemic hearts.