Economic analysis of thrombo inCode, a clinical-genetic function for assessing the risk of venous thromboembolism.

BACKGROUND: Patients with venous thromboembolism (VTE) commonly have an underlying genetic predisposition. However, genetic tests nowadays in use have very low sensitivity for identifying subjects at risk of VTE. Thrombo inCode(®) is a new genetic tool that has demonstrated very good sensitivity, thanks to very good coverage of the genetic variants that modify the function of the coagulation pathway. OBJECTIVE: To conduct an economic analysis of risk assessment of VTE from the perspective of the Spanish National Health System with Thrombo inCode(®) (a clinical-genetic function for assessing the risk of VTE) versus the conventional/standard method used to date (factor V Leiden and prothrombin G20210A). METHODS: An economic model was created from the National Health System perspective, using a decision tree in patients aged 45 years with a life expectancy of 81 years. The predictive capacity of VTE, based on identification of thrombophilia using Thrombo inCode(®) and using the standard method, was obtained from two case-control studies conducted in two different populations (S. PAU and MARTHA; 1,451 patients in all). Although this is not always the case, patients who were identified as suffering from thrombophilia were subject to preventive treatment of VTE with warfarin, leading to a reduction in the number of VTE events and an increased risk of severe bleeding. The health state utilities (quality-adjusted life-years [QALYs]) and costs (in 2013 EUR values) were obtained from the literature and Spanish sources. RESULTS: On the basis of a price of EUR 180 for Thrombo inCode(®), this would be the dominant option (more effective and with lower costs than the standard method) in both populations. The Monte Carlo probabilistic analyses indicate that the dominance would occur in 100 % of the simulations in both populations. The threshold price of Thrombo inCode(®) needed to reach the incremental cost-effectiveness ratio (ICER) generally accepted in Spain (EUR 30,000 per QALY gained) would be between EUR 3,950 (in the MARTHA population) and EUR 11,993 (in the S. PAU population). CONCLUSION: According to the economic model, Thrombo inCode(®) is the dominant option in assessing the risk of VTE, compared with the standard method currently used.

[Role of novel mitochondrial proteins in energy balance]. / Papel de nuevas proteínas mitocondriales en el balance energético.

Mitochondrial activity plays a key role in the control of thermogenesis and energy expenditure in homeothermic organisms. Recently, much attention has been paid to the novel protein members of UCP family as putative regulators of uncoupled respiration. Nevertheless, it is likely that other aspects, as yet unrecognized, of mitochondrial biology are also crucial to comprehend mitochondrial function. Thus, mitochondria are organized in filaments or in networks in many cell types as a result of the operation of fusion and fission events. The demonstration that mitofusin-2, a protein involved in mitochondrial fusion, stimulates the mitochondrial oxidation of substrates, cell respiration and mitochondrial membrane potential suggests that this protein may play an important role in mitochondrial metabolism, and as a consequence, in energy balance. Furthermore, the observation that mitofusin-2 expression is repressed in obese skeletal muscle suggests a posible role in the pathophysiology and/or etiopathogenesis of obesity.

Na(+)/H(+) exchange inhibitor cariporide attenuates cell injury predominantly during ischemia and not at onset of reperfusion in porcine hearts with low residual blood flow.

BACKGROUND: This study investigated whether myocardial protection by inhibition of Na(+)/H(+) exchange (NHE) occurs during ischemia and/or during reperfusion. METHODS AND RESULTS: The left anterior descending coronary artery was occluded in 32 pigs for 60 minutes and then reperfused for 24 hours. Infarct sizes (nitroblue tetrazolium [NBT] stain, histology) were determined at the end of the experiments. An extracorporeal bypass was used to achieve a constant residual blood flow of 3 mL/min in the myocardium at risk during ischemia. The NHE-1 inhibitor cariporide or distilled water was infused into the extracorporeal bypass system. In group 1, active treatment was administered from the onset of ischemia until 10 minutes of reperfusion (n=8). In group 2, active treatment was infused during the first 30 minutes of ischemia only (n=8). The group 3 animals (n=8) received intracoronary cariporide after 45 minutes of ischemia until 10 minutes of reperfusion. The control animals (group 4, n=7) were treated similarly to group 1 animals, with the cariporide solution being replaced by distilled water. Infarct sizes of group 1 (NBT stain, 41.5+/-20%; histology, 44. 6+/-12%) and group 2 (NBT stain, 33.5+/-14%; histology 34.9+/-15%) differed significantly (at least P:=0.012) from infarct sizes of group 3 (NBT stain, 71.6+/-15%; histology, 69.2+/-12%) and the control group (NBT stain, 76+/-9%; histology 72.4+/-12%). Cariporide treatment in group 1 and group 2 significantly improved functional recovery after 24 hours of reperfusion. CONCLUSIONS: Myocardial protection by cariporide is predominantly achieved by NHE inhibition during ischemia and not during early reperfusion.

Time-dependent protection by Na+/H+ exchange inhibition in a regionally ischemic, reperfused porcine heart preparation with low residual blood flow.

Inhibition of Na+/H+ exchange has been shown to protect the ischemic reperfused myocardium. This study investigated the time-dependent beneficial effect of the Na+/H+ exchange inhibitor HOE642 (4-isopropyl-3-methylsulphonylbenzoyl-guanedine methanesulphonite, cariporide). The left anterior descending coronary artery was ligated in 21 pigs (seven control animals) for 60 min and then reperfused for 24 h. An extracorporeal bypass system was used to achieve a constant residual blood flow of 3 ml/min within the ischemic myocardium. Cariporide (1 mg/kg) was injected intravenously in seven pigs after 15 min of ischemia (group A), and in another seven animals after 45 min of ischemia (group B). Histochemical (tetrazolium stain) and histologic infarct sizes were determined at the end of the experiments. Regional systolic shortening was determined by sonomicrometry. Mean calculated residual blood flows (ml/min/g of ischemic myocardium) amounted to 0.106 (group A), 0.093 (group B), and 0.117 (control group). Histochemical (32.9 +/- 21%) and histologic infarct sizes (36.7 +/- 17.7%) were significantly reduced in group A compared to both the control group (histochemical infarct size, 62.5 +/- 16.1%, P < 0.01; histologic infarct size. 67.8 +/- 16.3%, P = 0.013) and group B (histochemical infarct size 64.8 +/- 12.2%, P < 0.01; histologic infarct size 67.1 +/- 15.6%, P < 0.01). Infarct sizes of group B did not differ from control values. Recovery of regional systolic shortening after 24 h of reperfusion was insignificantly improved in group A compared to both other groups. In conclusion, inhibition of Na+/H+ exchange during early ischemia reduced cell death in an ischemic reperfused preparation with low residual blood flow.

Time delay of cell death by Na+/H+-exchange inhibition in regionally ischemic, reperfused porcine hearts.

Studies in different preparations have suggested that Na+/H+ exchange is one mechanism causally involved in cell death in myocardial ischemia and reperfusion. The time delay of cell death by pretreatment with the Na+/H+-exchange inhibitor HOE642, cariporide (4-isopropyl-3-methylsulphonylbenzoyl-guanidine methanesulphonate), was investigated in regionally ischemic, reperfused porcine hearts. HOE642 (1 mg/kg) was injected intravenously in 14 thoracotomized pigs 10 min before occlusion of the left anterior descending coronary artery (45 min of ischemia, six pigs; 70 min of ischemia, six pigs; 90 min of ischemia, two pigs). Ischemia was followed by 24 h of reperfusion. Six animals (45 min of ischemia) served as controls. Infarct size was determined as a ratio of infarcted (tetrazolium stain, histology) to ischemic myocardium (dye technique), and regional myocardial function was assessed by sonomicrometry. HOE642 did not affect global hemodynamic parameters. In the pretreated group with 45 min of ischemia, HOE642 significantly decreased histochemical infarct size from 51.2 +/- 12.6% (control group) to 13.2 +/- 12% (p < 0.005) and histologic infarct size from 44.5 +/- 9% to 17.1 +/- 7% (p < 0.005). Recovery of regional systolic shortening after 24 h of reperfusion was improved from 2 +/- 6% (control group) to 12 +/- 7% (p = 0.02). In addition, myocardial contracture and increase in heart rate during early reperfusion were attenuated. When ischemia was prolonged to 70 min after pretreatment with HOE642, infarct size, recovery of systolic shortening, myocardial contracture, and increase in heart rate did not differ from those of the control group. Pretreatment with HOE642 increased the tolerance to ischemia/reperfusion by approximately 20-25 min. Inhibition of Na+/H+ exchange appears to be very promising in the clinical treatment of acute myocardial ischemia and reperfusion.

Ultrastructural Evaluation of Postischemic Cell Death (Lethal Reperfusion Injury) in Porcine Hearts.

This study investigated whether reperfusion results in an increase of ultrastructurally determined myocardial injury in pig hearts. The left anterior descending coronary artery (LAD) was distally occluded in 12 pigs for 35-45 minutes and then reperfused for 3 hours. At the end of ischemia, as well as after 3 hours of reperfusion, one transmural biopsy was removed from the center of the risk region and subdivided into four-specimens, representing the subendocardial (I), subendo-midmyocardial (II), subepi-midmyocardial (III), and subepicardial layers (IV). The degree of injury was assessed by electronmicroscopy and was scored as reversible (1), an almost equal mixture of reversible and irreversible (2), and totally irreversible (3) damage. In addition, infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic (dye technique) myocardium. Infarct sizes ranged from 29.3% to 93% (mean 61.2%). The scores of injury of the four tissue layers before and after reperfusion did not differ significantly: layer I, 2.4 +/- 0.8/2.3 +/- 0.9; layer II, 2.2 +/- 0.9/2.0 +/- 0.9; layer III, 1.8 +/- 0.9/2.0 +/- 0.9; and layer IV, 1.6 +/- 0.9/1.3 +/- 0.6. The means of the four layers were almost identical at the end of ischemia (2.1 +/- 0.8) and after 3 hours of reperfusion (2.0 +/- 0.6). A linear regression analysis with 95% confidence limits of the score values before and after reperfusion indicated that maximally 25% of a mean final infarct size of about 50% may be due to lethal reperfusion injury. This study suggests that cell death in regional ischemia and reperfusion occurs predominantly during ischemia and not during reperfusion.

Myocardial protection by Na(+)-H+ exchange inhibition in ischemic, reperfused porcine hearts.

BACKGROUND: Studies in isolated myocytes and isolated heart preparations have suggested that Na(+)-H+ exchange is an important mechanism for myocardial ischemia-reperfusion injury. This study was undertaken to determine whether inhibition of Na(+)-H+ exchange limits infarct size and improves regional systolic shortening in regional ischemia and reperfusion in intact pigs. METHODS AND RESULTS: The left anterior descending coronary artery was occluded in 18 anesthetized and thoracotomized pigs for 45 minutes and then reperfused for 24 hours. As main end points of this study, regional systolic shortening (sonomicrometry) and infarct size (percentage of infarcted to ischemic myocardium) were determined at the end of the experiments. Infarcted myocardium was assessed by histochemistry (tetrazolium stain) and by quantitative histology of one heart slice. The Na(+)-H+ exchange inhibitor Hoe 694 was administered intravenously at a dose of 3 mg/kg in 6 pigs each either 10 minutes before ischemia (group A) or 10 minutes before the onset of reperfusion (group B). Six pigs served as controls (group C). Treatment with Hoe 694 before ischemia decreased histochemical infarct size from 65 +/- 18% (control group) to 13 +/- 8% (P < .01) and histological infarct size from 49 +/- 20% (control group) to 14 +/- 4% (P < .01). Histochemical (55 +/- 19%) and histological (42 +/- 15%) infarct sizes of group B were insignificantly reduced by 15%. Myocardial protection in group A was associated with an attenuated contracture after 10 minutes of reperfusion and an improved regional systolic shortening after 24 hours of reperfusion (group A, 25 +/- 12%; control group, 6 +/- 5%; P = .01). These parameters remained unaffected in group B. CONCLUSIONS: This study clearly demonstrates that Na(+)-H+ exchange is an important mechanism for cell death in myocardial ischemia and reperfusion in intact pigs; thus, inhibition of this exchange system may prove a promising new strategy in the clinical treatment of myocardial ischemia and reperfusion.

Comparative study on the effects of intracoronary nicorandil and nitroglycerin in ischaemic, reperfused porcine hearts.

The direct cardioprotective properties of nitroglycerin and nicorandil were compared in regionally ischaemic (45 min), reperfused (24 h) porcine hearts. Intracoronary treatments, which were started 15 min prior to occlusion of the distal left anterior descending coronary artery (LAD), were continuously administered for 105 min. The following equi-hypotensive drug dosages were used in nine pigs each; nitroglycerin 6 micrograms.kg-1 x min before ischaemia and during 45 min of reperfusion, 0.6 microgram.kg-1 x min during ischaemia; nicorandil 5 micrograms.kg-1 x min before ischaemia and during 45 min of reperfusion, and 0.5 microgram.kg-1 x min during ischaemia. Nine control animals were treated with isotonic sodium hydrochloride solution (1 ml.min-1). Despite comparable effects on blood pressure, intracoronary nicorandil, in contrast to intracoronary nitroglycerin, did not increase heart rate. Although neither drug affected coronary blood flow significantly, nicorandil substantially reduced regional myocardial oxygen consumption before coronary artery occlusion (-37 +/- 22%, P = 0.003 vs control group, P = 0.01 vs nitroglycerin treatment). Infarct sizes (tetrazolium method) after 45 min of ischaemia and 24 h of reperfusion were significantly decreased by nicorandil (control group 76.9 +/- 19%, nicorandil group 49.3 +/- 24%, P = 0.012) whereas nitroglycerin exhibited a borderline effect (62.5 +/- 15%, P = 0.054). Both treatments resulted in improved regional systolic shortening of the reperfused segment at the end of the experiments but this was not significant. At these drug dosages the direct cardioprotective action of nicorandil is slightly superior to nitroglycerin. This may be ascribed to its K-channel opening property associated with reduced regional myocardial oxygen consumption before the onset of ischaemia.

Effects of R56865, an Na(+)- and Ca(2+)-overload inhibitor, on myocardial injury in ischemic, reperfused porcine hearts.

The cardioprotective effect of R56865, an Na(+)- and Ca(2+)-overload inhibitor, was studied in 20 regionally ischemic reperfused (I/R) porcine hearts. Ten pigs were treated with a single intravenous (i.v.) injection of 0.4 mg/kg 15 min before occlusion of the distal left anterior descending coronary artery (LAD) for 45 min. Ten other animals served as controls. Infarct size (IS) was determined as percentage of infarcted (tetrazolium method) to ischemic (dye technique) myocardium after 24-h reperfusion. Regional systolic shortening (SS) was determined by sonomicrometry. Fifteen minutes after i.v. administration of R56865, a significant decrease in heart rate (HR) (from 83 +/- 15 to 74 +/- 16 beats/min), dP/dtmax (from 2,033 +/- 604 to 1,822 +/- 524 mm Hg/s), LAD blood flow (BF, from 17 +/- 7 to 14 +/- 7 ml/min), and calculated global myocardial O2 consumption (MVO2) (from 5.9 +/- 0.9 to 5.4 +/- 0.9 ml O2/min x 100 g) was observed. Although this investigational drug attenuated the increase in HR during early reperfusion, the incidence of ventricular fibrillation (VF) was not affected during either ischemia or reperfusion. R56865 reduced IS by 24% from 67.1 +/- 16% (control group) to 50.8 +/- 13%. In addition, this treatment improved systolic shortening after 24-h reperfusion from 6 +/- 8% (control group) to 15 +/- 9%. Our results support the concept that inhibition of intracellular Na(+)- and Ca(2+)-overload is a promising new principle in treatment of myocardial I/R.

Effect of epinephrine treatment during late ischemia and early reperfusion on regional myocardial function and infarct size in partially infarcted reperfused porcine hearts.

This study investigated whether epinephrine treatment during late ischemia and early reperfusion improves systolic shortening after 45 minutes of reperfusion at the cost of increased infarct size. A model consisting of both stunned and dead myocytes was used. The left anterior descending coronary arteries of 10 control and 10 treated pigs were occluded distally for 40 minutes and then reperfused for 3 days. Regional systolic shortening was determined by sonomicrometry, and infarct size was assessed as the percentage of infarcted (tetrazolium stain) to ischemic (dye technique) myocardium. Intravenous administration of epinephrine was started 10 minutes before the onset of reperfusion (5 micrograms/min) and continued until 45 minutes of reperfusion (mean 18 micrograms/min). Immediately before and during 45 minutes of reperfusion, left ventricular peak pressure, dp/dtmax, and heart rate were significantly increased in the treated animals. After 45 minutes of reperfusion, epinephrine treatment improved systolic shortening of the reperfused myocardium (treated group 9% +/- 8%; control group -1% +/- 6%; p < 0.01). Transient beta-adrenergic stimulation of the reperfused myocardium did not increase infarct size (treated group 57.2% +/- 19%; control group 55.4% +/- 17%). In conclusion, epinephrine treatment during late ischemia and early reperfusion improved systolic shortening after 45 minutes of reperfusion without affecting infarct size.

Postischemic cell death in reperfused porcine hearts is not attenuated by the spin trap agent PBN during early reperfusion.

Ischemic, reperfused porcine hearts were used to investigate whether the spin trap agent PBN (N-tert-butyl-alpha-phenylnitrone) attenuates postischemic cell death by scavenging of free radicals. The left anterior descending coronary artery (LAD) was ligated distally in 16 pigs for 45 min and then reperfused for 3 h. PBN (coronary concentration approximately 1 mM) was infused into the LAD of eight pigs during the first 45 min of reperfusion. Electron spin resonance spectroscopy (ESR) was performed to identify free radical adducts in the reperfused coronary venous blood. Regional systolic shortening (SS%) was determined by sonomicrometry. Infarct size was evaluated as the percentage of infarcted (tetrazolium stain) to ischemic (dye technique) myocardium. The transmural ultrastructural degree of myocardial injury as well as myocardial ATP levels were assessed at the end of the experiment. Intracoronary treatment with PBN during early reperfusion did not attenuate myocardial damage. Infarct sizes (control group 59 +/- 19%, treated group 55 +/- 14%), transmural ultrastructural alterations, myocardial ATP concentrations (control group 1.8 +/- 0.3 mumol/mg frozen weight, treated group 1.7 +/- 0.4 mumol/mg) and regional systolic shortening at the end of the experiments (control group -1 +/- 5%, treated group -2 +/- 6% did not differ significantly. Furthermore, under various experimental conditions of spin trapping, free radical adducts could not be identified in coronary venous blood during early reperfusion. The results suggest that the spin trap agent PBN (1 mM) does not affect postischemic cell death in porcine hearts.

Interstitial myocardial neutrophil accumulation between 3 and 72 h of reperfusion does not significantly affect infarct size in porcine hearts.

The inflammatory response--mediated by activated neutrophils--is assumed to play an important role in the pathogenesis of reperfusion injury. This study investigated whether extravascular myocardial neutrophil accumulation between 3 and 72 h of reperfusion affects infarct size in porcine hearts. The left anterior descending coronary artery was ligated distally in 24 pigs for 45 min and reperfused for 3 h (n = 8), 24 h (n = 8), or 72 h (n = 8). Infarct size and extravascular myocardial accumulation of neutrophils was evaluated at the end of the experiments. Global hemodynamic characteristics were comparable for the three groups both before and during ischemia. Neutrophil count/mm2 reperfused myocardium increased substantially from 4 +/- 2 (3 h of reperfusion) to 129 +/- 70 (24 h of reperfusion, p < 0.001). After 3 d of reperfusion, the neutrophil count had decreased to 10 +/- 7. The invasion of neutrophils between 3 and 24 h of reperfusion did not significantly affect the extent of myocardial necrosis. Infarct sizes after 3 h (62.6 +/- 20%), 24 h (71.8 +/- 13%), and 72 h of reperfusion (67.6 +/- 18%) did not differ significantly. This finding does not suggest that a significant amount of myocytes are destroyed by extravasated neutrophils between 3 and 72 h of reperfusion.

Failure of chronic, high-dose, oral vitamin E treatment to protect the ischemic, reperfused porcine heart.

Lipid peroxidation, presumably the result of free radical-mediated injury, has been shown to occur during myocardial ischemia and reperfusion. Since vitamin E is a very effective, naturally occurring, chain-breaking antioxidant, it was investigated whether a vitamin E-supplemented diet increased myocardial tolerance towards ischemia and reperfusion in pigs. In addition to a standard diet which contained 30 mg vitamin E/kg (approximately daily vitamin E intake 30 mg), ten pigs were fed with 10 g vitamin E (all-rac-alpha-tocopherol acetate, Merck AG, Darmstadt, Germany) daily for at least 4 weeks. Ten control pigs remained on the standard diet. In an open chest preparation, the left anterior descending coronary artery was distally ligated for 45 min followed by 3 d of reperfusion. Infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic myocardium (dye technique). Regional systolic shortening was evaluated by sonomicrometry. Vitamin E concentrations in plasma and myocardium were measured by high-performance liquid chromatography. Global hemodynamic characteristics did not differ between the two groups. Oral pretreatment with vitamin E raised the plasma concentration of this vitamin from 1.1 +/- 0.3 to 5.0 +/- 1.0 mg/l and the myocardial content from 4.2 +/- 0.7 to 18.6 +/- 2.7 ng/mg fresh weight. Vitamin E treatment did not reduce infarct size, which amounted to 71.3 +/- 5% in the control group and to 71.7 +/- 8.2% in the treated animals. Furthermore, recovery of regional systolic shortening of the reperfused segment did not significantly differ in the two groups after 3 d of reperfusion; it measured 2 +/- 4% in the controls and 6 +/- 6% (p = 0.16) in the treated animals. Therefore, chronic, oral treatment with vitamin E which raised myocardial and plasma concentrations of this vitamin 4- to 5-fold did not increase myocardial tolerance towards ischemia and reperfusion in this animal model.

Myocardial distribution of indium-111-antimyosin Fab and technetium-99m-sestamibi in experimental nontransmural infarction.

Early revascularization in acute myocardial infarction results in normal, necrotic and partially damaged and partially salvaged ("intermediate") myocardium. By combining a perfusion tracer and a marker for myocardial injury, we attempted to differentiate between these three types of cardiac tissue. The LAD was occluded in nine pigs for 45 min and then reperfused. After 48 and 72 hr, 74 MBq 111In-antimyosin Fab and 740 MBq 99mTc-sestamibi, respectively, were injected intravenously. Normally perfused myocardium was labeled with fluorescein and the heart excised. Three to four slices were cut from the apex. Tetrazolium staining revealed the zone of necrosis. Tracer distribution on double-nuclide scintigrams of the slices also reflected the three different myocardial zones. Guided by fluorescence and macrohistochemistry, tissue samples were excised from each zone. In relation to normal myocardium, mean activity in the intermediate zone was 0.82 +/- 0.20 for 99mTc-sestamibi and 2.84 +/- 1.31 for 111In-antimyosin Fab. Activity in necrotic myocardium was 0.30 +/- 0.19 and 3.95 +/- 2.47, respectively. These results show that 111In-antimyosin Fab fragments not only accumulate in necrotic but also in intermediate myocardium. Therefore, an overestimation of infarct size may occur if 111In-antimyosin Fab fragments are used alone without a perfusion tracer.

The effects of Trolox, a water-soluble vitamin E analogue, in regionally ischemic, reperfused porcine hearts.

Myocardial protection by the water-soluble vitamin E analogue, Trolox, was investigated in 18 regionally ischemic, reperfused porcine hearts. The left anterior descending coronary artery was distally ligated for 45 min and was reperfused for three days. Five grams of Trolox (n = 9) were infused intravenously before coronary occlusion. Treatment was continued with an intravenous dose of 5 grams Trolox/24 hours until the end of the experiment. Infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic myocardium (dye technique). Regional systolic shortening was assessed by sonomicrometry. Generation of free radicals by stimulated neutrophils was evaluated by luminol-enhanced chemiluminescence. Plasma concentrations of Trolox were measured by high-performance liquid chromatography. Aside from heart rate before ischemia, global hemodynamic values including calculated left ventricular oxygen consumption did not differ significantly between the two groups. Plasma concentrations of Trolox measured 1.8 +/- 0.3 mmol/l (before ischemia), 0.96 +/- 0.13 mmol/l (before reperfusion), 0.77 +/- 0.1 mmol/l (40 min of reperfusion), and 0.08 mmol/l (end of the experiment). Generation of free radicals by stimulated neutrophils was reduced by about 30% in the treatment group before ischemia and immediately before reperfusion, but was not reduced at the end of the experiment. Risk regions (control group 19.4 +/- 6 g, treatment group 19.3 +/- 7 g) and infarct sizes (control group 69.3 +/- 8%, treatment group 69.3 +/- 12%) were almost identical. Regional systolic shortening of a control segment and of the risk region were similar in both groups before ischemia, before reperfusion, and after 45 min of reperfusion. After 3 days of reperfusion, regional systolic shortening of the reperfused myocardium of the treated group had recovered to a significantly greater extent (P = 0.027). This parameter amounted to 9 +/- 6% in the treated group and to 3 +/- 3% in the control group. Improved functional recovery was not accompanied by higher tissue concentrations of adenosine triphosphate. It is concluded that the chosen treatment with Trolox does not reduce infarct size but accelerates functional recovery. This finding suggests that the mechanisms resulting in myocardial necrosis during ischemia/reperfusion and in post-ischemic myocardial dysfunction may differ.

Failure of iloprost to protect the regionally ischemic, reperfused porcine heart.

The effect of iloprost (Schering AG, Berlin), a stable prostacyclin analogue, was investigated in ischemic, reperfused porcine hearts. The left anterior descending coronary artery (LAD) was distally occluded in 18 pigs for 45 min followed by 3-d of reperfusion. Nine pigs were continuously treated with iloprost at a dose of 25 ng/kg per min. Treatment was started as intracoronary infusion into the proximal LAD 10 min before occlusion. The intercoronary infusion was replaced by an intravenous infusion after 45 min of reperfusion, which was continued until the end of the experiment. Infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic myocardium (dye technique). Regional systolic shortening was assessed by sonomicrometry. Myocardial concentrations of adenosine triphosphate were evaluated at the end of the experiment. Generation of free radicals by stimulated polymorphonuclear neutrophils was determined by luminol-enhanced chemiluminescence. Histologic and immunohistologic techniques were applied to characterize the myocardial inflammatory response. Global hemodynamics did not differ between the two groups. Neither infarct size (control group 68 +/- 18%, treated group 74 +/- 14%), recovery of systolic shortening (control group 3 +/- 6%, treated group 6 +/- 6%), nor myocardial adenosine triphosphate concentrations were improved by iloprost treatment. Myocardial inflammatory response remained unaffected by this treatment. The capacity of coronary venous, stimulated polymorphonuclear neutrophils to generate free radicals was slightly suppressed in the treated group before ischemia, at the end of ischemia and during early reperfusion. In this preparation, iloprost did not exhibit any beneficial effect on infarct size, recovery of systolic shortening and myocardial adenosine triphosphate concentrations.

Modulation of the inflammatory response in experimental myocardial infarction.

The role of inflammation in reperfused, ischaemic myocardium was assessed morphologically in 39 porcine hearts after 24 h (n = 23) and 72 h (n = 16) of reperfusion and after different antiphlogistic treatments. The left anterior descending coronary artery (LAD) was occluded distally for 45 min. Seven pigs received BW755C (10 mg kg-1) i.v. prior to ischaemia (A), eight pigs were given the same dose before 24 h of reperfusion (B), and eight pigs were treated with iloprost (25 ng kg-1 min-1) i.v. before occlusion and continuously for 72 h (C). Two groups of eight pigs each served as controls for 24 h (D) and 72 h (E) of reperfusion. Infarct sizes were determined, myocardium was investigated by light microscopy, and polymorphonuclear leucocytes (PMNs) and macrophages were quantitated after histo- and immunohistochemical staining. Jeopardized myocardium contained 129 neutrophils mm-2 and 120 macrophages mm-2 (D) vs 10 neutrophils mm-2 and 290 macrophages mm-2 (E). Neutrophils and infarct sizes were only significantly decreased in group A (68 neutrophils mm-2, 30% reduction of infarct size). Macrophages infiltration was not significantly affected for all treatment groups (A, B, C). It is concluded that myocardial infarct sizes are neutrophil-mediated postischaemic tissue injury can be reduced by BW755C applied prior to ischaemia. Neutrophil-mediated myocardial injury is unlikely to occur beyond 3 days of reperfusion.

Acute treatment with vitamin E does not protect the regionally ischemic, reperfused porcine heart.

Thirty pigs were randomly assigned to a blind treatment with vitamin E or placebo. Ten animals each received 0.5 g d-alpha tocopherol intravenously before ischemia (group 1) or before reperfusion (group 2). Ten control pigs were treated with a lipid emulsion as placebo. The left anterior descending coronary artery was distally ligated for 45 min followed by 3 days of reperfusion. Infarct size was determined as ratio of infarcted (tetrazolium stain) to ischemic myocardium (dye technique). Regional systolic shortening was assessed by sonomicrometry. Myocardial and plasma concentrations of vitamin E were determined by high-performance liquid chromatography. Global hemodynamic parameters and estimated left ventricular oxygen consumption did not differ among the three groups. Intravenous treatment with vitamin E raised the plasma levels of this vitamin from 1 +/- 0.3 mg/l (control group) to 21 +/- 6 mg/l before ischemia, to 4 +/- 2 mg/l before reperfusion and to 2 +/- 0.6 mg/l at the end of the experiments in group 1. In group 2, vitamin E plasma levels increased from 1 +/- 0.3 mg/l to 24 +/- 13 mg/l before reperfusion and to 2 +/- 0.6 mg/l after 3 days of reperfusion. At the end of the experiments, myocardial vitamin E concentrations amounted to 4.2 +/- 0.7 ng/mg fresh weight (control group), 9.7 +/- 2.1 ng/mg (group 1), and to 8.7 +/- 1.4 ng/mg (group 2). The increase in vitamin E plasma concentration was not associated with a cardioprotective effect. Infarct sizes of the three groups (group 1: 68 +/- 12%, group 2: 66 +/- 15%, control group: 69 +/- 8%) were almost identical.(ABSTRACT TRUNCATED AT 250 WORDS)

Combined treatment with vitamins E and C in experimental myocardial infarction in pigs.

The effect of two different combined treatments with vitamin E acetate and vitamin C on infarct size and recovery of regional myocardial function was investigated in ischemic, reperfused porcine hearts. The left anterior descending coronary artery was distally ligated in 30 thoracotomized pigs for 45 minutes followed by 3 days of reperfusion. Infarct size was determined as the ratio of infarcted (tetrazolium stain) to ischemic (dye technique) myocardium. Regional myocardial function was assessed by sonomicrometry. Ten pigs received vitamin E acetate (12 gm intravenously three times for 1 week) before ischemic and vitamin C (4.4 gm intravenously) before reperfusion (therapy A). Another 10 pigs were treated with vitamin E acetate (12 gm intraarterially) and vitamin C (4.4 gm intravenously) during ischemia (therapy B). An additional 10 pigs served as a control group. Global hemodynamics did not differ significantly among the groups before and during ischemia. Mean plasma concentrations of vitamin E amounted to 107 micrograms/ml in group A, 16 micrograms/ml in group B, and 0.9 micrograms/ml in the control group at the onset of reperfusion. Therapy A reduced the size of the infarct from 73 +/- 12% to 47 +/- 16% of the region at risk (p less than 0.005) and improved regional systolic shortening from 0 +/- 7% to 11 +/- 6% at 3 days after reperfusion (p less than 0.01). Therapy B decreased the size of the infarct to 64 +/- 9% of the region at risk (p = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)