Performance of allografts and xenografts for right ventricular outflow tract reconstruction.

BACKGROUND: We compared the long-term durability of allografts and xenografts implanted for reconstruction of the right ventricular outflow tract. METHODS: A total of 401 patients were studied from January 1974 to June 2000 (145 xeno- and 256 allografts), follow-up being 98% complete. We analyzed freedom from reoperation and allograft specific factors that may indicate degeneration. RESULTS: The age at implantation was 2 days to 31 years (median 4.0 years). Conduit exchange rate was similar (p = 0.2) for conduit diameters less than 15 mm (41%+/-9% for allografts, 30%+/-6% for xenografts), but significantly different (p = 0.02) for diameters of 15 mm or larger (60%+/-8% for allografts, 30%+/-10% for xenografts). Diagnosis-related 20-year survival analysis showed a significantly (p = 0.01) better survival of patients with tetralogy of Fallot/pulmonary atresia (83%+/-5%) and Rastelli-type surgery (81%+/-8%) compared with patients with truncus arteriosus communis (69%+/-8%). ABO-compatibility, preservation method, and aortic or pulmonary allograft could not be identified as risk factors for allograft longevity. CONCLUSIONS: For smaller diameters (less than 15 mm), allografts exhibit no advantage over xenografts, whereas in larger diameters (15 mm or larger) allografts are the conduit of choice for the right ventricular outflow tract.

Exercise capacity and mid-term survival in patients with tricuspid atresia and complex congenital cardiac malformations after modified Fontan-operation.

OBJECTIVE: Continued follow-up of the Fontan population group is mandatory in order to evaluate the best approach for long term treatment. We studied exercise capacity and survival in patients with either right atrial to right ventricular (Fontan-Bjoerk, RA-RV) anastomosis or right atrial to pulmonary artery (RA-PA) connection. METHODS: Between January 1980 and December 1995 Fontan-Bjoerk modifications were performed in 73 patients with tricuspid atresia. A RA-PA anastomosis (performed either with direct atrio-pulmonary connection or with a lateral tunnel of autologous atrial tissue) was used in 118 patients with single ventricle or complex cardiac malformations. Using bicycle ergospirometry and impedance cardiography standard variables of exercise testing were measured in 15 patients with RA-RV and in 18 patients with RA-PA connection. A group of 23 healthy pupils served as controls. RESULTS: Follow-up was complete for 97.9% (n = 187) of all operated patients. Survival (% mean +/- SEM) at 5, 10 and 15 years was 89.3 +/- 3.6, 76.8 +/- 0.6 and 63.6 +/- 10.5 for RA-RV connection and 80.2 +/- 4.0, 75.3 +/- 4.5 and 64.6 +/- 10.7 for RA-PA connection (P = 0.12) respectively. Exercise capacity was tested after a median time of 6.0 (0.8-19.8) years after Fontan operation in RA-RV and of 7.8 (4.3-18.2) years in RA-PA patients. Total work load was equal in the two Fontan groups, but it was below normal. Heart rate, respiratory rate, oxygen uptake and ventilatory equivalent for oxygen were not different between the two Fontan groups. Cardiac index and stroke volume index were consistently lower at anaerobic threshold and at maximal exercise in RA-PA patients compared with controls. CONCLUSION: Survival analysis between RA-RV and RA-PA Fontan connection failed to demonstrate a better outcome for patients with either Fontan modification. Although there was a tendency for RA-RV connection to adapt cardiac output more efficient to exercise compared with RA-PA patients, total work load and ventilatory equivalent was not significantly different between the two Fontan modifications. We conclude, that by incorporation of a residual subpulmonary ventricular chamber within the Fontan circulation no additional benefit for exercise capacity could be observed.

Allograft implantation in pediatric cardiac surgery: surgical experience from 1982 to 1994.

Between July 1982 and April 1994, a total of 290 patients (median age 6.5 years, range 1 month to 32.1 years, 69 patients younger than 1 year) underwent repair of their cardiac malformation by insertion of an allograft. The diagnoses were truncus arteriosus communis (n = 78, 27.0%), tetralogy of Fallot (n = 59, 20.0%), pulmonary atresia (n = 72, 25.0%), double outlet right ventricle (n = 15, 5.0%), complex transposition of the great arteries plus pulmonary stenosis (n = 37, 13.0%), and others (n = 29, 10.0%). Either pulmonary (n = 69) or aortic (n = 221) cadaver allografts were implanted. Two hundred twenty-nine of the allografts were antibiotic preserved. Since January 1991 (n = 61), a new cryopreservation procedure was employed for standardized uniform cooling using heat sinks and defined package geometry. Follow-up was complete for 95.2% (n = 276, 1,320 patient-years). Thirty-day mortality was 9.0% (n = 26) and late mortality was 12.1% (n = 35). Kaplan-Meier analysis revealed that patient survival was determined mainly by their underlying cardiac disease. All allografts with valve sizes less than 15.0 mm had to be exchanged within 7 years as these patients had outgrown their conduits. When the allograft was larger than 15.0 mm, exchange was necessary in 20% at 10 years. ABO compatibility and aortic or pulmonary origin of the allograft were not significant influences on allograft survival.(ABSTRACT TRUNCATED AT 250 WORDS)

[Thoracoscopic surgery of the lung and pleura]. / Thoracoskopische Chirurgie an Lunge und Pleura.

134 operations were performed using video-thoracoscopic techniques for patients, with diffuse lung disease (48), pneumothorax (46), peripheral coin lesions (29) und others (11). In 92% of the patients video-thoracoscopic operation was completed. Open reoperation was indicated only in patients with persistent pneumothorax (3). After hospital discharge open reoperation was performed once for recurrent pneumothorax. From our experience we conclude, that thoracoscopic surgery may be routinely indicated in future for lung biopsies, pneumothorax, peripheral coin lesions and pleural products.

Inhibition of plasma kallikrein with aprotinin in porcine endotoxin shock.

Activation of the contact phase of coagulation has been implicated in the pathogenesis of septic shock. We wanted to determine if inhibition of plasma kallikrein can prevent arterial hypotension and liberation of kinins from kininogen, induced by an infusion of bacterial lipopolysaccharide (LPS) in anesthetized, ventilated 20-kg pigs. The LPS was given IV in a dose of 5 micrograms/kg/h for 8 hours. The plasma kallikrein inhibitor aprotinin, 537 mumol, was given IV during 8 hours, resulting in plasma levels above 10 mumol/L. Ten animals (SA) received LPS and aprotinin and ten randomized controls (SC) received LPS and saline. Kinin-containing kininogen was determined on the basis of the amount of kinin releasable in plasma samples by incubation with trypsin. Kininogen decreased to 58% +/- 4% of the baseline value without any difference between groups. This may indicate participation of other processes than degradation by plasma kallikrein in the decrease of kininogen. Arterial blood pressure was higher at 7 hours in the SA animals than in the SC group (101% +/- 11% vs. 68% +/- 8%; mean +/- SEM; p = 0.026). Fibrin monomer and C3adesArg plasma levels were attenuated by aprotinin treatment. These findings underscore the important role of the contact system in LPS shock.

Surgical evaluation of the modified Fontan procedure.

From 1980 to 1990 152 patients underwent Fontan operation at our institution. The following patient groups were identified: 1. patients with tricuspid atresia (n = 82, 54.0%); 2. patients with single ventricle (n = 31, 20.3%); 3. patients with a wide variety of non correctable, complex cardiac malformations (n = 39, 25.7%). In 27.0% of the patients a primary Fontan operation was performed. 45.0% of the patients received a previous shunt to increase pulmonary blood flow and in 29.4% of the patients a pulmonary artery band was placed to reduce pulmonary flow. Overall mortality was not significantly different in patients with previous palliative procedures (19.4%, n = 18) as compared to 17.4% (n = 6) in patients with primary Fontan operation. Risk of death was high in the group with complex cardiac malformations (28.2%, n = 11) and in patients with single ventricle (19.4%, n = 6). Early mortality was considerably less in patients tricuspid atresia (8.5%, n = 7). Postoperatively patients with incorporation of the residual right ventricular chamber and pulmonary valve (Fontan-Bjoerk) showed a significant (p less than 0.05) lower incidence of pleural effusion as compared to patients with other modifications of the Fontan procedure. Actuarial survival rate of all patients is 83.8 +/- 3.1% (mean +/- SEM) at ten years. The modified Fontan procedures are providing an accepted surgical method for patients with otherwise non correctable cardiac malformations.

Effect of the elastase inhibitor eglin C in porcine endotoxin shock.

We wanted to demonstrate that the neutrophil elastase inhibitor eglin C reduces the loss of intravascular protein in endotoxin (LPS) shock and that effective concentrations are present in lymph. We used 45 anesthetized miniature pigs in a randomized, controlled trial. LPS 10 micrograms/kg/hr was given for 6 hr. Recombinant eglin C was given before LPS (250 nmol/kg) and continuously at 250 nmol/kg/hr (n = 18); septic controls received saline (n = 18); nine nonseptic controls were used. Eglin C significantly reduced the loss of intravascular protein (plasma volume times plasma protein concentration) from -0.79 g/kg in septic controls to 0.42 g/kg in eglin C-treated animals and reduced plasma concentration of neutrophil elastase, bound to the leukocyte neutral protease inhibitor (LNPI), but systemic hypotension was unchanged. Six additional pigs were anesthetized, prepared with a thoracic lymph fistula, and received eglin C at 475 nmol/kg/hr; three received saline; three received LPS. Eglin C concentrations in lymph were comparable to those in plasma. We conclude that eglin C reduced the loss of intravascular protein during LPS shock and attained effective concentrations in lymph.

A triazolodiazepine platelet activating factor receptor antagonist (WEB 2086) reduces pulmonary dysfunction during endotoxin shock in swine.

We wanted to determine the effects of WEB 2086, a platelet activating factor (PAF) antagonist, in lipopolysaccharide (LPS) shock in anesthetized pigs. In a randomized study, LPS from S. abortus equi, 2 micrograms/kg/h was given IV for six hours. Thirteen animals received LPS and WEB 2086, 10 mg/kg/h IV for 6.5 hours, beginning 30 minutes before LPS. Eleven septic controls received saline and LPS, three nonseptic controls received saline and WEB 2086, and three nonseptic controls received saline only. In six animals we investigated the effect of synthetic PAF in doses between 50 and 10,000 ng on arterial (AP) and pulmonary arterial (PAP) pressure before and during infusion of WEB 2086. The LPS-induced rise in PAP was reduced by WEB 2086 (p = 0.01) but not the decrease in AP. The LPS-induced leukopenia, hypoxia, increase in airway pressure, and release of plasminogen activator inhibitor were reduced by WEB 2086. Platelet activating factor produced an increase in PAP and a biphasic response in AP. All PAF dose response curves were shifted to the right by WEB 2086. Platelet activating factor was a pulmonary hypertensive agent and contributed to the LPS-induced respiratory alterations.

A purified antithrombin III--heparin complex as a potent inhibitor of thrombin in porcine endotoxin shock.

Inhibition of activated clotting factors is an important therapeutic approach in disseminated intravascular coagulation (DIC). We examined the possible protective effect of a purified complex of human antithrombin III (AT III) and heparin in endotoxin-induced DIC in pigs. Two groups of endotoxemic pigs were studied. AT III-heparin group pigs (n = 8) were pretreated with a bolus injection of 500 units AT III-heparin complex, followed by a continuous infusion of 1000 units of the complex for 6 hours given simultaneously with the infusion of 10 micrograms/kgh of S. abortus equi endotoxin. Controls (n = 9) were given saline in addition to the continuous infusion of endotoxin. AT III activity, prothrombin and soluble fibrin in plasma were determined by chromogenic substrate methods. Fibrinogen was measured turbidimetrically. Human AT III antigen in the treated group was 64 +/- 3% at 2 hours and increased to 84 +/- 4% until the end of the experiment. AT III activity in the AT III-heparin group was elevated throughout the whole observation period (greater than 100%), whereas it was significantly lower in the controls. Prothrombin decreased similarly in both groups by approximately 35% until the end of the experiment. AT III-heparin treatment significantly attenuated the endotoxin-induced consumption of fibrinogen and completely prevented the increase in soluble fibrin in plasma. However, no significant effect of AT III-heparin was observed on endotoxin-induced mortality and dysfunction in pulmonary gas exchange. Therefore we conclude that the purified AT III-heparin complex inhibits thrombin effects and prevents development of DIC, but fails to significantly influence clinical outcome in endotoxin shock of the pig.

Therapeutic effects of the combination of two proteinase inhibitors in endotoxin shock of the pig.

Thrombin activation is an important underlying pathomechanism for septic organ failure. The selective thrombin inhibitor, hirudin, reduces the endotoxin-induced fibrinogen consumption and thus the formation of fibrin monomer, as well as the pulmonary vasoconstriction in pigs at plasma concentrations of 70 to 100 nmol/l. PMN cell activation with subsequent release of digestive proteases is in part responsible for the loss of fluid and protein from the vascular compartment during septic shock. Administration of the inhibitor of PMN elastase, cathepsin G and mast cell chymase, eglin C, reduces the loss of intravascular protein during the first 4 hours of endotoxin shock at plasma concentrations in the range of 2 mumol/l.

The hypotensive response to des-Arg9-bradykinin increases during E. coli septicemia in the pig.

The sensitivity to des-Arg9-bradykinin of the cardiovascular system was largely increased in piglets with E. coli bacteremia. However, the sensitivity to bradykinin was unchanged under the same condition. These findings indicate the appearance of the kinin B1-receptor in the systemic circulation of the pig during septicemia. Bradykinin induced responses suggest a stable effect mediated by the classical B2-receptor.

Endotoxin shock in the rat: reduction of arterial blood pressure fall by the bradykinin antagonist B4148.

The selective competitive bradykinin (BK) antagonist (B4148) produced significant inhibition of the hypotensive effect of BK in rats. Using a rat model of endotoxin shock, the fall in mean arterial blood pressure to an intravenous injection of lipopolysaccharide from E. coli was significantly attenuated by the B4148 as compared to controls. These findings suggest that kinins are involved in the hypotensive response to endotoxin shock in rats. The development of potent BK antagonists offers a new experimental approach for evaluating the role of kinins in this and other disease states.

Attenuation of arterial blood pressure fall in endotoxin shock in the rat using the competitive bradykinin antagonist Lys-Lys-[Hyp2, Thi5,8, DPhe7]-Bk (B4148).

The selective competitive bradykinin (Bk) antagonist, B4148 (Lys-Lys-[Hyp2, Thi5,8, DPhe7]-Bk) infused at 100 micrograms kg-1 min-1 into rats produced a significant inhibition of the hypotensive effect of Bk and had no effect against acetylcholine-induced responses. In a rat model of endotoxin shock, the fall in mean arterial blood pressure in response to an intravenous injection of lipopolysaccharide from E. coli was significantly attenuated by the same infusion of B4148 compared to controls. These findings suggest that kinins are involved in the hypotensive response to endotoxin shock in rats. The development of potent Bk antagonists offers a new experimental approach for evaluating the role of kinins in this and other disease states and potential therapy in such disorders.

Prostaglandin synthetase inhibitors are not beneficial in the hypercatabolic state of acute uremia in rats.

In rats the effect of prostaglandin synthetase inhibition on the enhanced protein degradation in acute uremia was investigated. After 48 h of bilateral nephrectomy the urea nitrogen appearance, an indicator of net protein degradation, was calculated, and N tau-methylhistidine (N tau-MH) serum concentration was measured for judging myofibrillar breakdown. Also serum urea nitrogen, creatinine, and potassium serum concentrations were followed up. All bilateral nephrectomized rats showed severe uremic disturbances with increased (P less than 0.01) concentrations of serum urea nitrogen, creatinine, and potassium. Moreover, the urea nitrogen appearance and N tau-MH serum concentration increased (P less than 0.05) significantly. Administration of indomethacin (4 mg.kg-1b.wt./12 hi.p.) in bilateral nephrectomized rats did not influence the analyzed parameters significantly. Thus, we could not demonstrate a positive influence on the increased skeletal muscle degradation in acutely uremic rats by prostaglandin synthetase inhibition. These data suggest that in our model of acute uremia prostaglandins do not play a major role in the degradation of striated muscle.

Reduction of urea generation and muscle protein degradation by adrenalectomy in acutely uremic rats.

The effect of adrenalectomy on the enhanced protein degradation in acute uremia was investigated. Therefore, serum urea nitrogen, urea N appearance and Nt-methylhistidine were followed in bilaterally nephrectomized rats. At 48 h after induction of uremia the animals displayed serum urea nitrogen levels of 223 +/- 9.5 mg/dl as compared to 26.0 +/- 1.0 mg/dl in sham-treated rats. This increment was significantly attenuated in acutely uremic, adrenalectomized animals (176 +/- 6.0 mg/dl). When these rats were substituted with corticosterone (5 mg/kg body weight), serum urea nitrogen readily increased to levels of acutely uremic animals with intact adrenal glands (225 +/- 6.0 mg/dl). The net generation of urea, as determined by the urea N appearance, was significantly increased during acute uremia (370 +/- 26 mg/48 h) as compared to SHAM animals (220 +/- 15 mg/48 h). This increment of urea formation could almost be completely reversed by simultaneous adrenalectomy (238 +/- 20 mg/48 h). When these rats were substituted with corticosterone, the urea N appearance rebounded to values quite comparable to acutely uremic rats with intact adrenal glands (363 +/- 30 mg/48 h). To determine whether skeletal muscle proteins might serve as a source for the enhanced protein degradation in acute uremia, plasma levels of Nt-methylhistidine were measured. Bilaterally nephrectomized rats had Nt-methylhistidine values of 9.6 +/- 1.0 micrograms/ml. In acutely uremic rats without adrenal glands, Nt-methylhistidine levels were found to be significantly decreased (6.0 +/- 0.4 micrograms/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Observations on the microvascular repair process after confluent argon laser photocoagulation.

We observed the repair process of the choriocapillaris after confluent argon laser retinal photocoagulation in the domestic cat with a plastic injection-corrosion technique coupled with scanning electron microscopy and transmission electron microscopy. Confluent photocoagulation was applied to the area of the retinal tapetum, creating two kinds of lesions: one consisted of five confluent burns and the other of 20 confluent burns. Specimens were prepared at 1, 30, and 60 days. Occlusion of the choriocapillaris was noted regardless of the length of time after photocoagulation. The only sign of repair was noted at 60 days when the choriocapillaris located at the edge of the lesion showed a uniform rearrangement. Transmission electron microscopy revealed severe damage to the endothelial cells, with lack of cell activation and permanent capillary closure in the vessels of the lesion proper.