Superiority of the University of Wisconsin solution over simple crystalloid for extended heart preservation

In Vivo Comparative Study of Two Lactobionate Based Solutions for Prolonged Heart Preservation

The duration of safe heart preservation must be improved. Using a heterotopic heart transplantation model, we compared in vivo the recovery of rabbits hearts preserved with a K+ Lactobionate based fluid (UW: University of Wisconsin solution) or with a Na+Lactobionate based fluid. In the “preservation” group, hearts were cold stored (4°C) for 6 hours with UW (n=9) or Na+Lactobionate solution (n=9). In the “transplantation” group, cold storage was followed by 3 hours of reperfusion (UW: n=8, Na+Lactobionate solution: n=7). Functional recovery, adenine nucleotide pool, circulating blood cardiac enzymes, circulating blood and tissue malondialdehyde (MDA) were measured. Left ventricular enddiastolic and developed pressures at different preload levels were better after preservation with UW than with Na+Lactobionate solution (p<0.05). Also with UW, adenosine diphosphate and total adenine nucleotide content were significantly higher than with Na+Lactobionate solution (p<0.05) whereas adenosine triphosphate, monophosphate and energy charges were similar. Cardiac enzymes and tissue MDA were similar with UW and Na+Lactobionate solution. In circulating blood, MDA was not detected. These results enhance the superiority of UW solution over a Na+Lactobionate based solution for long term heart preservation.

Use of (all-blood) miniplegia versus crystalloid cardioplegia in an experimental model of acute myocardial ischemia

PURPOSE

Several methods of myocardial protection have been used. The use of all-blood solutions modified with glutamate and aspartate has increased. Its use in situations of acute ischemia provides improved contractile function, "resuscitating" the previously lesioned muscle. The dilution preconized by literature is around 25% of the hematocrit. The present study evaluates an all-blood cardioplegia solution with tepid 1% dilution, denominated miniplegia.

MATERIAL AND METHOD

Pigs of the Large-White breed were used with an isolated heart and perfused with blood of a support animal. Three groups (n = 7 per group) were designated with the following treatments: Control group (CO), St. Thomas solution (ST), continuous normothermic all-blood solutions (SG). After the stabilization period, systolic pressure (PS), diastolic pressure (PD), developed pressure (PD), stress of the wall, elastance, and passive stiffness were recorded. The hearts were submitted to 30 minutes of regional ischemia with the clamping of the anterior interventricular artery, and subsequently to 90 minutes of global ischemia with the use of the three different treatments during this period. At the beginning of global ischemia, the coronary clamp was removed. The hearts were again reperfused. Upon three minutes into reperfusion the hearts were defibrillated when necessary. Measurements were taken every 30 minutes to 90 minutes into reperfusion.

RESULTS

The SG presented a better recovery of the ventricular function in several of the parameters recorded. The ST group was inferior to the SG group, which in turn was superior to the CO group in some of the parameters analyzed. A higher number of defibrillations were needed to reestablish coordinated heart beats in the ST and CO groups. There were no differences related to the percentage of wet weight between the SG and ST groups, and the percentage was higher in the CO group.

CONCLUSION

The use of all-blood miniplegia provided superior protection when compared to global ischemia or crystalloid cardioplegia in acutely ischemic hearts. The model employed is very close to the clinical situation due to the use of blood as a perfusate.

Celsior Preserved Cardiac Mechanoenergetics Better Than Popular Solutions in Canine Hearts

BACKGROUND

Better protective effects of Celsior on cardiac function than the other conventional solutions have been reported in acute experiments and in clinical trials for at-risk patients. However, no study has yet precisely elucidated how these preservation solutions affect cardiac mechanoenergetics. Therefore, we evaluated the effects of St. Thomas' Hospital solution No. 2, University of Wisconsin solution, and Celsior on left ventricular contractility (Emax: end-systolic pressure-volume ratio) and oxygen consumption.

METHODS

We used 32 canine excised cross-circulated hearts. Twenty-three hearts served as donor hearts after hypothermic ischemia with one of the three solutions, and the remaining 9 served as controls. After arrest with each solution, the hearts were preserved for 4 hours at 4 degrees C. Then, we measured left ventricular pressure, volume, and oxygen consumption to obtain Emax and the relation between ventricular pressure-volume area (a measure of total mechanical energy) and oxygen consumption. We also evaluated the oxygen cost of Emax by changing Emax with calcium administration.

RESULTS

Celsior did not significantly affect E(max) (6.3 +/- 2.4 in control versus 5.3 +/- 1.3 mm Hg.mL(-1).100 g with Celsior) nor the oxygen cost of Emax (1.2 +/- 0.6 versus 1.6 +/- 0.5 mL O2.mL.mm Hg(-1).beat(-1).100 g(-2), respectively). In contrast, St. Thomas' Hospital and University of Wisconsin solutions significantly decreased Emax (4.5 +/- 1.1 and 3.5 +/- 0.9 mm Hg.mL(-1).100 g, respectively) and increased the oxygen cost of Emax (2.5 +/- 0.8 and 2.4 +/- 0.9 mL O2.mL.mm Hg(-1).beat(-1).100 g(-2), respectively) compared with control and Celsior-preserved hearts. The slope and intercept of the oxygen consumption versus pressure-volume area relation showed no significant difference among the four groups.

CONCLUSIONS

Celsior showed better protective effects on cardiac mechanoenergetics than St. Thomas' Hospital and University of Wisconsin solutions in the acute phase of heart transplantation.

Histidine-tryptophan-ketoglutarate solution maximally preserves endothelium-derived hyperpolarizing factor-mediated function during heart preservation: comparison with University of Wisconsin solution

BACKGROUND

The University of Wisconsin (UW) solution is used widely in heart preservation but has been demonstrated to be detrimental to the endothelial function. The present study compares the effect of histidine-tryptophan-ketoglutarate (HTK) and UW solutions on endothelium-derived hyperpolarizing factor (EDHF)-mediated function in porcine small coronary arteries.

METHODS

An isometric force study was performed in a myograph and the membrane potential of a single smooth muscle cell was measured electrophysiologically. Small coronary arteries (diameter 457 +/- 15 microm) were incubated with UW (n = 8), HTK (n = 7) or Krebs solution (n = 15) at 4 degrees C for 4 hours. After washout, in the presence of indomethacin (Indo; 7 micromol/liter), N(G)-nitro-l-arginine (l-NNA; 300 micromol/liter) and oxyhemoglobin (HbO; 20 micromol/liter), bradykinin (BK; -10 to -6.5 log M)-induced relaxation was compared in U46619 (-8 log M) pre-contraction. EDHF-mediated hyperpolarization was elicited by BK (-6.5 log M) in the presence of Indo, l-NNA and HbO.

RESULTS

BK-induced, EDHF-mediated relaxation was reduced from 93.6 +/- 2.8% to 79.7 +/- 4.6% after UW preservation (p = 0.01 by unpaired t-test and p = 0.005 by 2-way analysis of variance [ANOVA]), whereas HTK incubation did not decrease EDHF-mediated relaxation (87.0 +/- 6.5%, p = 0.3 by unpaired t-test and p = 0.6 by 2-way ANOVA, compared with control, and p = 0.001 by 2-way ANOVA, compared with UW). EDHF-mediated hyperpolarization (10.3 +/- 1.6 mV) was attenuated by UW exposure (3.4 +/- 0.6 mV, [p = 0.002] vs control), but not by HTK exposure (8.3 +/- 1.1 mV, [p = 0.3] vs control).

CONCLUSIONS

HTK is superior to UW solution in protecting EDHF-mediated endothelial function in porcine small coronary arteries. The present findings supports the use of HTK solution in heart preservation.

Standardization of an isolated pig heart preparation with parabiotic circulation: methodological considerations

In the present study we standardized an experimental model of parabiotic circulation of isolated pig heart. The isolated heart was perfused with arterial blood from a second animal as support and submitted to regional ischemia for 30 min, followed by total ischemia for 90 min and reperfusion for 90 min. Parameters for measurement of ventricular performance using different indices measured directly or indirectly from intraventricular pressure were defined as: maximum peak pressure, final diastolic pressure, pressure developed, first derivative of maximum pressure (dP/dt max), first derivative of minimum pressure (dP/dt min), systolic stress of the left ventricle (sigmas), and maximum elastance of the left ventricle. Isolated hearts subjected to regional and global ischemia presented significant worsening of all measured parameters. Less discriminative parameters were dP/dt max and dP/dt min. Elastance was the most sensitive parameter during the reperfusion period, demonstrating an early loss of ventricular function during reperfusion. The model proved to be stable and reproducible and permitted the study of several variables in the isolated heart, such as ischemia and reperfusion phenomena, the effects of different drugs, surgical interventions, etc. The model introduces an advantage over the classical models which use crystalloid solutions as perfusate, because parabiotic circulation mimics heart surgery with extracorporeal circulation.

A comparative study of Celsior and University of Wisconsin solutions based on 12-hr preservation followed by transplantation in canine models

BACKGROUND

Celsior is a recently developed extracellular-type preservation solution that is effective in organ preservation. This experimental study was designed to compare the effects of Celsior and University of Wisconsin (UW) solutions in myocardial protection, using 12-hour preservation followed by orthotopic transplantation.

METHODS

Fourteen pairs of adult mongrel dogs were divided into 2 groups. In the UW group (n = 7), UW solution at 4 degrees C was used for coronary vascular washout and storage following cardiac arrest with glucose-insulin-potassium (GIK) solution. In the Celsior group (n = 7), Celsior solution was used to produce cardiac arrest, for coronary vascular washout, and for storage. After 12-hour cold preservation, orthotopic transplantation was performed under cardiopulmonary bypass (CPB). The rate of recovery (%) of cardiac function of donor hearts was compared 1 and 2 hours after weaning from CPB, and then the transplanted hearts were harvested for histological study.

RESULTS

Hemodynamic parameters including cardiac output, left ventricular pressure (LVP), and the maximum rates of positive and negative increase of LVP after transplantation were significantly (p < 0.05) higher in the Celsior group than in the UW group 2 hours after weaning from CPB. The transmission electron microscopic study found that degeneration of the mitochondria in the Celsior group was less extensive than in the UW group.

CONCLUSION

Celsior solution enhanced the cardiac function of hearts preserved for 12 hours prior to transplantation compared to UW solution. Our results indicate that Celsior solution is equivalent or superior to UW solution for cardiac preservation.

The influence of temperature on metabolic and cellular protection of the heart during long-term ischemia: a study using P-31 magnetic resonance spectroscopy and biochemical analyses

We have compared the influence of two different cold temperatures (below 10 degreesC) for cardiac ischemia by measuring a large variety of hemodynamic and metabolic parameters during ischemia and reflow. Isolated isovolumic rat hearts were arrested with a preservation solution which was developed in our laboratory and then submitted to 5 h of cold storage (4 degreesC, group I; and 7.5 degreesC, group II) in the same solution. After an additional period of 50 min of ischemia at 15 degreesC with intermittent cardioplegic infusion, hearts were reperfused for 60 min at 37 degreesC. Function was assessed during the control period and reflow. High-energy phosphates and intracellular pH were followed by 31P magnetic resonance spectroscopy. Analyses of metabolites and enzymes were performed by biochemical assays and HPLC in coronary effluents and in freeze-clamped hearts to assess cellular integrity. The energetic pool was better preserved at 4 degreesC during ischemia (ATP at the end of 4 degreesC ischemia, 59 +/- 7% in group I vs 31 +/- 5% in group II, P < 0.01) and reflow (P < 0.05) but membrane protection was higher when increasing the temperature to 7.5 degreesC (reduction of creatine kinase leakage, 89 +/- 16 IU/min in group I vs 51 +/- 5 IU/min in group II, P < 0.05). As a result, functional recovery, represented by the rate pressure product, was higher in hearts preserved at 7.5 degreesC (52 +/- 6% recovery in group I vs 77 +/- 7% in group II at the end of reflow, P < 0.05). Altogether, cold storage at 7.5 degreesC provides a better protection than storage at 4 degreesC.

Effects of cardioplegic solutions on the vasoreactivity of the internal mammary artery

BACKGROUND

During free internal mammary artery grafting, cardioplegia administration can be performed through the internal mammary artery. The present study examined whether cardioplegic solutions produce arterial graft constriction and functional endothelial damage.

METHODS

Forty internal mammary artery segments from 10 patients were incubated in Krebs solution (n=10), University of Wisconsin solution (n=10), Broussais Hospital solution (n=10), or blood cardioplegia (n=10).

RESULTS

There was a significant difference in sensitivity to norepinephrine between segments in Krebs solution and those in University of Wisconsin solution or Broussais Hospital solution but not segments in blood cardioplegia. There was a significant difference in relaxation to acetylcholine between segments in Krebs solution and those in the three other cardioplegic solutions and between those in blood cardioplegia and segments in University of Wisconsin solution or Broussais Hospital solution. There was no significant difference in relaxation to sodium nitroprusside between segments in any of the solutions.

CONCLUSIONS

These experiments suggest that storage in the different cardioplegic solutions studied does not preserve the initial vasoreactivity of the internal mammary artery. However, blood cardioplegia appears to be less deleterious in regard to endothelial and myogenic vascular function.

Effect of pressure on myocardial function after 6-hour preservation with blood cardioplegia

BACKGROUND

This study examined the return of cardiac function in pig hearts after 6 hours' preservation by continuous perfusion with blood cardioplegia at two perfusion pressures compared with preservation with crystalloid solutions.

METHODS

Isolated pig hearts were randomly divided into five groups (n = 8 per group) according to the following treatments: group 1 = fresh hearts (control); group 2 = hearts arrested with Queen's cocktail cardioplegia and then immersion in 0 degrees C saline solution (QS group); group 3 = hearts arrested with (5 degrees C) and simple immersion in 0 degrees C University of Wisconsin solution (UW group); and groups 4 and 5 = hearts arrested with blood cardioplegia at 10 degrees C and then continuously perfused at a pressure of 80 cm H2O or 40 cm H2O, respectively (groups BC80 and BC40). After preservation for 6 hours, donor hearts were reperfused by a cross-circulation support pig. Thereafter, cardiac function and metabolism were examined every half hour for 2 hours. A three-way mixed general linear model was used to analyze data with repeated measures. Bonferroni test was used to determine differences (p < or = 0.05) between groups.

RESULTS

Only 4 hearts recovered electric activity in the BC80 group (p < or = 0.05 versus other groups). There was poor recovery of left ventricular work in the BC80 group compared with the other groups (p < 0.001). Left ventricular work in the QS and UW groups was also lower than in the control and BC40 groups. Left ventricular work in the BC40 group fully recovered. Maximum elastance did not differ between groups. Compliance was reduced in the QS, BC80, and BC40 groups versus controls after preservation (p < 0.006). Coronary flow decreased and coronary vascular resistance increased in the BC80 group versus the other groups (p < or = 0.001). Coronary flow in the QS, UW, and BC40 groups was lower than in the control group (p < 0.001). The magnitude of lactate release was much higher in the BC80 group than in the other groups (p < or = 0.001).

CONCLUSIONS

Continuous perfusion with 10 degrees C blood cardioplegia at 40 cm H2O pressure for 6 hours provided adequate preservation of systolic function in this model. University of Wisconsin solution provided the best protection of diastolic function.

Organ preservation solutions in heart transplantation--patterns of usage and related survival

Despite experimental advantages for certain heart preservation solutions (HPS), their clinical popularity and related survival are uncertain. We surveyed all active UNOS heart transplant centers to determine their HPS. HPS survival benefits were tested using the UNOS heart transplant registry. Centers used from 1 to 3 types of 167 solutions. Of these formulations, 55.1% were commonly cited solutions. The other (custom) mixtures differed from those usually reported. All solutions were classified as intracellular (I, [Na++] < 70 mEq/L) or extracellular (E, [Na++] > or = 70 mEq/L). Significant variations in solution usage were observed among major regions of U.S. transplant activity (Northeast [NE], Southeast [SE], and West [W], P < 0.001). For example, 62.5% of University of Wisconsin (UW) and 49.3% of "Other" usage occurred in the NE; 75% of Roe and 100% of Collins usage occurred in the SE; and 100% of Krebs and 46% of Stanford usage occurred in the W. Logistic regression analyses of 9401 patients who underwent transplantation from 10/87 to 12/92 showed a reduction in the adjusted one month mortality odds ratio for grafts preserved with I rather than E solutions (0.85, P < 0.05). Compared with the most commonly used solution, Plegisol (20.1% of cases), the following adjusted odds ratios for one-month mortality were observed: UW, 1.09 (ns); Stanford, 0.80 (P < 0.10); Roe, 0.36 (P < 0.001); Collins, 0.82 (ns); Krebs, 0.14 (P < 0.01). Using the same one month comparison with Plegisol, 16.8% of grafts that received Custom-I solutions also fared better (0.75, P < 0.05) than the 21.4% that had Custom-E mixtures (0.91, ns). HPS usage varies greatly and there are regional preferences. There may be early survival benefits for certain intracellular HPS--however, further study is warranted to explore such relationships.

Ischemic preconditioning enhances donor heart preservation

Ischemic preconditioning has not been assessed in an experimental model for myocardial preservation during heart transplantation. Using isolated working rat hearts, ischemic preconditioning was investigated as an adjunct to isolated hypothermic (group 1), crystalloid (group 2: University of Wisconsin solution; group 3: St. Thomas' Hospital cardioplegic solution II; group 4: Bretschneiders' cardioplegic solution), and noncrystalloid (group 5: cold blood cardioplegia) preservation during a 10-hr period of global ischemia at 4 degrees C. After acquisition of functional baseline data, ischemic preconditioning was induced with one cycle of 5 min of normothermic ischemia and 5 min of reperfusion before induction of global hypothermic ischemia (n= 10/group). Nonpreconditioned hearts (n= 10/group) were assessed for control. Ischemic preconditioning improved postischemic: functional recovery. Thus, aortic flow after 60 min of reperfusion recovered to 0%, 8%, 0%, 1% and 0% in control groups 1 to 5 without ischemic preconditioning and 21%, 25%, 10%, 8%, and 3% in groups 1 to 5 with ischemic preconditioning. The same pattern of recovery was observed in regard to postischemic maximum developed left ventricular pressure, which recovered to 21%, 56%, 30%, 36%, and 19% in groups 1 to 5 without preconditioning and 46%, 75%, 49%, 40%, and 47% in the corresponding groups with ischemic preconditioning. High-energy phosphate contents were not significantly different between preconditioned hearts and corresponding nonpreconditioned control hearts. Creatine kinase leakage during early reperfusion was found to be reduced with ischemic preconditioning. Thus, we have demonstrated that ischemic preconditioning can improve contractile function after global hypothermic ischemia in the isolated rat heart and we have shown that this protection is additive to that of hypothermia-induced protection during global ischemia at 4 degrees C. This endogenous mechanism of cardioprotection was effective regardless of whether preservation was accomplished using cardioplegic solution or topical hypothermia alone. This may have clinical implications in myocardial preservation for heart transplantation.

Successful 24-hour rabbit heart preservation by hypothermic continuous coronary microperfusion with oxygenated University of Wisconsin Solution

BACKGROUND

This study assessed whether a combination of hypothermic continuous coronary microperfusion and oxygenated University of Wisconsin Solution (UWS) improves postischemic functional recovery and minimizes myocardial tissue edema.

METHODS

Isolated rabbit hearts were divided into four groups (n = 6 each): group I (immediate reperfusion), group II (simple cold storage in UWS), group III (hypothermic continuous coronary microperfusion with UWS), and group IV (hypothermic continuous coronary microperfusion with oxygenated UWS). Hearts in groups II, III, and IV were preserved for 24 hours. Preischemic and postischemic cardiac function was measured using a Langendorff apparatus.

RESULTS

Hearts in group I showed complete functional recovery, whereas cardiac output in group II was inadequate. In groups III and IV, the percentage recovery rate (post/pre) of cardiac output was 57.0% +/- 3.1% and 82.2% +/- 9.1%, respectively (p < 0.05). In groups III and IV, perfusion pressures at the end of 24-hour preservation increased from the initial 5 mm Hg to 12.3 +/- 2.7 and 8.3 +/- 1.4 mm Hg (p < 0.05), respectively. In groups I, III, and IV, the percentage tissue water content was 82.8 +/- 1.0, 86.7 +/- 1.7, and 83.8 +/- 1.6, respectively (p < 0.05 for group III versus groups I and IV). There was a significant correlation between the percentage tissue water content and coronary perfusion pressure at the end of the 24-hour preservation (r = 0.60, p = 0.040) and a significant inverse correlation between percentage tissue water content and percentage recovery rate of cardiac output (r = -0.69, p = 0.014). In ultrastructural examination, myocardial tissue edema was limited and mitochondria were well preserved in group IV.

CONCLUSION

We conclude that the combination of a hypothermic continuous coronary microperfusion technique and oxygenation of UWS was the procedure of choice for reducing tissue edema and improving both the coronary microcirculation and functional recovery during 24-hour heart preservation.

Adenosine pretreatment for prolonged cardiac storage. An evaluation with St. Thomas' Hospital and University of Wisconsin solutions

Adenosine pretreatment has been shown to be beneficial in several models of ischemia-reperfusion. We wished to evaluate whether adenosine pretreatment is cardioprotective for prolonged cardiac storage and whether the presence of adenosine in the storage media affects the results. Isolated rodent hearts were obtained from Sprague-Dawley rats, mounted on a Langendorff apparatus, instrumented with an intraventricular balloon, and ventricularly paced at 300 beats/min. Four groups of hearts were studied in a 2 x 2 factorial experiment (n = 8 to 12 per group). Hearts were subjected to normal perfusion or to solution supplemented with adenosine 50 mumol/L for 10 minutes followed by adenosine-free perfusion for 10 minutes. Hearts then were stored for 8 hours at 0 degrees C in either University of Wisconsin solution (adenosine 5 mmol/L) or St. Thomas' Hospital II solution (adenosine free). Adenosine pretreatment increased tissue levels of adenosine triphosphate before storage (p = 0.04). Nonfunction was less common after storage (1/19 versus 6/20 hearts, p < 0.05), and diastolic function was better preserved in the adenosine groups in the reperfusion phase (p = 0.01). The beneficial effects of adenosine pretreatment were independent of which storage solution was used. Developed pressure was increased (p < 0.05) and release of creatine kinase and lactate dehydrogenase was reduced (p < 0.0001) in hearts treated with University of Wisconsin solution compared with those treated with St. Thomas' Hospital solution. These studies suggest that adenosine pretreatment improves recovery after prolonged hypothermic storage and that the presence of adenosine in the preservation solution does not alter the results. The experiments provide further evidence that extended myocardial protection is better enhanced with University of Wisconsin solution than with St. Thomas' Hospital II solution.

Protective effect of monoclonal antibodies against LFA-1 and ICAM-1 on myocardial reperfusion injury following global ischemia in rat hearts

The effects of anti-LFA-1 and anti-ICAM-1 monoclonal antibodies (MAbs) on the reperfusion injury of rat cardiac tissues after global ischemia were studied. Studies were performed using an isolated blood perfused heart preparation in which hearts were subjected to 30 min of global ischemia followed by 40 min of reperfusion. Isolated rat hearts were perfused with blood from an anesthetized support rat with or without anti-LFA-1 or anti-ICAM-1 monoclonal antibody administration (n = 10 in each group). Ventricular function, myocardial tissue water content and myocardial energy status were evaluated in this model. In the control group, ischemia and reperfusion of isolated hearts resulted in a 63.6 +/- 2.7% recovery of left ventricular developed pressure (LVDP) and a 44 +/- 7% increase in coronary vascular resistance compared with pre-ischemic baseline values. Treatment with anti-LFA-1 MAb or anti-ICAM-1 MAb resulted in a 77.2 +/- 1.5% and a 80.4 +/- 3.0% recovery of LVDP, respectively. In addition, increase in coronary vascular resistance was only 23 +/- 7% and 13 +/- 6% in anti-LFA-1 and anti-ICAM-1-treated groups, respectively. Values are significantly different between the control group and MAb-treated groups. Ischemia and reperfusion resulted in a 16% increase of myocardial tissue water content (3.71 +/- 0.03 in pre-ischemic baseline versus 4.29 +/- 0.08 ml/g dry weight) in the control group, whereas that resulted in only 3.0 and 5.7% increase in anti-LFA and anti-ICAM-1-treated groups, respectively. The difference between the control group and MAb-treated groups was significant. Cardiac energy status as assessed by adenosine triphosphate (ATP) concentration was markedly reduced in the control group at 40 min of reperfusion compared with pre-ischemic baseline values (5.70 +/- 0.27 vs. 14.92 +/- 0.48 mumol/g dry weight). In contrast, the reduction of myocardial ATP concentration at 40 min of reperfusion was significantly inhibited by anti-LFA-1 and anti-ICAM-1 monoclonal antibody treatment (5.70 +/- 0.27 vs. 8.96 +/- 0.52 and 8.10 +/- 0.47 mumol/g dry weight, respectively). These results suggest that a LFA-1/ICAM-1 pathway plays a critical role in the pathogenesis of postischemic myocardial injury during early reperfusion period.

Pressure-volume loops: a dynamic approach to the assessment of ventricular function

Analysis of ventricular function in terms of pressure-volume or pressure-dimension relationships allows global and regional ventricular dynamics to be fully analyzed. In addition, this approach allows the relationships between muscle function (contractility, stiffness, potential energy) and pump function (stroke volume, stroke work) to be determined and predicted. Alterations in ventricular loading conditions can also be examined in terms of muscle and pump function. However, this analysis is more complex than initially thought and considerable care must be taken especially when regional ischemia is concerned. Moreover, some of the early assumptions have been disproved and conclusions can only be drawn from studies in which full assessment of changes in pressure and dimensions is available.