Superior qualities of University of Wisconsin solution for ex vivo preservation of the pig heart.

The components of the University of Wisconsin solution have the potential to enhance and extend heart preservation. We have evaluated University of Wisconsin solution by comparing it with St. Thomas' Hospital cardioplegic solution in the isolated pig heart subjected to 8 hours of ischemia at 4 degrees C (n = 6 in each). The hearts were perfused ex vivo with enriched autologous blood for the control and the postpreservation assessments. Morphologic, metabolic, and functional evaluations were performed. Left and right ventricular function as assessed by the slope values of systolic and diastolic pressure-volume relationships of isovolumically contracting isolated heart was better preserved by University of Wisconsin solution (percent reduction: left ventricular systolic, 52.4% +/- 5.5% versus 17.7% +/- 6.7% [p less than 0.001]; right ventricular systolic, 125.6% +/- 46.4% versus 65.5% +/- 31.4% [p less than 0.05]; right ventricular diastolic, 112.3% +/- 48.7% versus 40.2% +/- 31.3% [p less than 0.02] after St. Thomas' Hospital and University of Wisconsin preservation, respectively). Postischemic recovery of left ventricular rate of rise of pressure and myocardial oxygen consumption were significantly improved after University of Wisconsin preservation (percent reduction, rate of rise of pressure: St. Thomas' Hospital 39.3% +/- 8.1%; University of Wisconsin 18.1% +/- 4.6%; percent reduction, myocardial oxygen consumption St. Thomas' Hospital 55.1% +/- 6.9%, University of Wisconsin 24.8% +/- 6.7%; p less than 0.001). Microvascular functional integrity as assessed by coronary vascular resistance was well maintained throughout the postischemic period and was similar to the preischemic control value in the University of Wisconsin group. By contrast, a significant increase was found at the beginning of postpreservation reperfusion, with a progressive rise thereafter in the St. Thomas' Hospital group (p less than 0.001). Preservation of myocardial adenosine triphosphate was improved and energy charge was unchanged after 8 hours of ischemia and reperfusion in the University of Wisconsin-preserved hearts compared with the St. Thomas' Hospital-preserved hearts (p less than 0.01). Electron microscopic examination revealed substantially better preservation of the contractile apparatus after preservation with University of Wisconsin solution. Myocytes from hearts receiving University of Wisconsin solution, unlike those given St. Thomas' Hospital solution, showed relaxed myofibrils with prominent I-bands. We conclude that University of Wisconsin solution has the potential to improve the preservation of the heart and possibly prolong the ischemic period in clinical cardiac transplantation.     

Protection of the immature myocardium during global ischemia. A comparison of four clinical cardioplegic solutions in the rabbit heart

Controversy surrounds the reported beneficial effects of crystalloid cardioplegic solutions in the immature myocardium. In the present study we have investigated the efficacy of four clinical cardioplegic solutions in the immature myocardium to determine (1) whether cardioplegic protection could be demonstrated and, if so, (2) the relative efficacy of the four solutions. Isolated, working hearts (n = 6 per group) from neonatal rabbits (aged 5 to 8 days) were perfused aerobically (37 degrees C) for 20 minutes before a 2-minute infusion of one of four cardioplegic solutions: The St. Thomas' Hospital No. 2, Tyers, Bretschneider, and Roe solutions. Hearts were then rendered globally ischemic for 50 minutes at 37 degrees C before reperfusion for 15 minutes in the Langendorff mode and 20 minutes in the working mode. The postischemic recovery of cardiac function and leakage of creatine kinase were compared with results in noncardioplegic control hearts. Good protection was observed with the St. Thomas' Hospital and Tyers solutions: The postischemic recovery of cardiac output was increased from 21.2% +/- 12.7% in the cardioplegia-free group to 79.4% +/- 6.2% and 72.9% +/- 4.4%, respectively, in the St. Thomas' Hospital and Tyers groups (p less than 0.01). In contrast, no protection was observed with either the Bretschneider or Rose solutions: Cardiac output recovered to 31.7% +/- 10.3% and 5.1% +/- 3.2%, respectively, in these groups. Postischemic creatine kinase leakage was 72.4 +/- 12.3 and 92.1 +/- 18.6 IU/15 min/gm dry weight in the St. Thomas' Hospital and Tyers groups compared with 125.6 +/- 28.6 IU/15 min/gm dry weight in control hearts (p = no significant difference). In the Bretschneider group, creatine kinase leakage increased to 836.9 +/- 176.8 IU/15 min/gm dry weight (p less than 0.01 versus noncardioplegic control hearts), and with the Roe solution the value was 269.0 +/- 93.0 IU/15 min/gm dry weight (p = no significant difference). In conclusion, cardioplegic protection can be achieved in the immature rabbit myocardium with both St. Thomas' Hospital and Tyers solutions, but acalcemic solutions such as Bretschneider and Roe solutions (which may be effective in the adult heart) increased damage in this preparation. The reported lack of cardioplegic efficacy in the immature myocardium may therefore reflect the choice of cardioplegic solution rather than a greater vulnerability to injury in the neonatal heart.     

St. Thomas' Hospital cardioplegic solution. Beneficial effect of glucose and multidose reinfusions of cardioplegic solution

The intention of this study was to determine whether glucose is beneficial in a cardioplegic solution when the end products of metabolism produced during the ischemic period are intermittently removed. The experimental model used was the isolated working rat heart, with a 3-hour hypothermic 10 degrees C cardioplegic arrest period. Cardioplegic solutions tested were the St. Thomas' Hospital No. 2 and a modified Krebs-Henseleit cardioplegic solution. Glucose (11 mmol/L) was beneficial when multidose cardioplegia was administered every 30 minutes. Including glucose in Krebs-Henseleit cardioplegic solution improved postischemic recovery of aortic output from 57.0% +/- 1.8% to 65.8% +/- 2.2%; p less than 0.025. The addition of glucose to St. Thomas' Hospital No. 2 cardioplegic solution improved aortic output from 74.6% +/- 1.9% to 87.4% +/- 1.9%; p less than 0.005. Furthermore, a dose-response curve showed that a glucose concentration of 20 mmol/L gave no better recovery than 0 mmol/L, and glucose in St. Thomas Hospital No. 2 cardioplegic solution was beneficial only in the range of 7 to 11 mmol/L. In addition, we showed that multidose cardioplegia was beneficial independent of glucose. Multidose St. Thomas' Hospital No. 2 cardioplegia, as opposed to single-dose cardioplegia, improved aortic output recovery from 57.4% +/- 5.2% to 74.6% +/- 1.9%; p less than 0.025, and with St. Thomas' Hospital No. 2 cardioplegic solution plus glucose (11 mmol/L) aortic output recovery improved from 65.9% +/- 2.9% to 87.4% +/- 1.9%; p less than 0.005. Hence, at least in this screening model, the St. Thomas' Hospital cardioplegic solution should contain glucose in the range of 7 mmol/L to 11 mmol/L, provided multidose cardioplegia is given. We cautiously suggest extrapolation to the human heart, on the basis of supporting clinical arguments that appear general enough to apply to both rat and human metabolisms.     

Effect of four crystalloid cardioplegias on immature rabbit hearts during global ischaemia

OBJECTIVE: Controversy surrounds the reported beneficial effects of crystalloid cardioplegic solutions in the immature myocardium. In the present study, we investigated the efficacy of four clinical cardioplegic solutions in the immature myocardium to determine if cardioplegic protection could be demonstrated and, if yes, the relative efficacy of the four solutions. METHODS: Isolated, working hearts (n=6 per group) from neonatal rabbits (age, 7-14 days) were perfused aerobically (37 C) for 15 minutes in the Langendorff mode and 30 minutes in the working mode before a 2-minute infusion of one of four cardioplegic solutions: the modified St. Thomas' Hospital no. 1 cardioplegic solution, Tyers solution, Bretschneider solution or Roe solution. Hearts were then rendered globally ischaemic for 120 minutes at 14C before reperfusion for 15 minutes in the Langendorff mode and 30 minutes in the working mode. The post-ischaemic recovery of cardiac function and leakage of myocardial enzymes (GOT, CK, CK-MB, LDH, LDH1) were compared with results in non-cardioplegic control hearts. RESULTS: Good protection was observed with modified St. Thomas' Hospital and Tyers solutions: postischaemic recovery of cardiac output was increased from 80.43+/-3.62% in the non-cardioplegic group to 85.19+/-3.12% and 70.66+/-3.48% in the St. Thomas' Hospital and Tyers groups (p<0.05), respectively. In contrast, no obvious protection was observed with either the Bretschneider or Roe solutions: cardiac output recovered to 45.08+/-3.16% and 30.06+/-2.59%, respectively. Post-ischaemic CK leakage was 19.83+/-2.14 IU/mL and 21.17+/-2.32 IU/mL in the St. Thomas' Hospital and Tyers groups (p>0.05). In the Bretschneider group, CK leakage increased to 30.00+/-3.16 IU/mL (p<0.01 vs. non-cardioplegic control hearts), and in the Roe group, CK leakage was 31.00+/-5.10 IU/mL (p<0.05 vs. cardioplegic-free hearts). Post-ischaemic ATP was 1.98+/-0.54 micromol/g*dry weight and 1.35+/-0.39 micromol/g*dry weight in the St. Thomas' Hospital and Tyers groups (p<0.01 vs. non-cardioplegic control group), respectively. In the Bretschneider group, ATP decreased to 0.91+/-0.16 micromol/g*dry weight (p<0.05 vs. non-cardioplegic control hearts), and in the Roe group to 0.88+/-0.10 micromol/g*dry weight (p<0.01 vs.cardioplegic-free hearts). CONCLUSION: In conclusion, cardioplegic protection can be achieved in the immature rabbit myocardium with both St. Thomas' Hospital and Tyers solutions, but acalcaemic solutions such as Bretschneider and Roe solutions increased damage. The reported lack of cardioplegic efficacy in the immature myocardium may, therefore, reflect the choice of cardioplegic solution rather than a greater vulnerability to injury in the neonatal heart.     

Cultured neonatal rat cardiomyocytes and 99mTc-sestamibi to assess the direct effects of cardioplegia.

The efficacy of cardioplegia in neonatal myocardial protection is still a matter of debate. 99mTc-sestamibi cellular accumulation reflects sarcolemmal and mitochondrial electrical gradients. It was used to monitor the direct effects of two cardioplegic solutions, modified St Thomas' Hospital and Bretschneider, on normoxic and metabolically-inhibited cultured cells. Cellular accumulation of 99mTc-sestamibi, expressed by the ratio between intra and extra cellular concentrations, was assessed in three different sets of neonatal rat cardiomyocytes. Cells were either treated with different concentrations of modified St Thomas' solution (50, 75, 100%), they were treated or recovering from a treatment with modified St Thomas and Bretschneider solutions at 50% concentrations, or were recovering from treatment with modified St Thomas' and Bretschneider solution at 50% concentrations mixed with metabolic inhibitors. Cardioplegia depressed the tracer accumulation in a concentration-dependent manner. This effect was independent of the type of cardioplegia (120-min uptake, as a percentage of control values, modified St Thomas' 68+/-12 and Bretschneider 59+/-7) and was rapidly reversible. Cardioplegia was unable to prevent the depression of tracer accumulation induced by metabolic inhibitors and even induced a deleterious effect (120-min uptake, as a percentage of control values, metabolic inhibitors 69+/-12, metabolic inhibitors + modified St Thomas 38+/-14, metabolic inhibitors + Bretschneider 43+/-6) during recovery after 30 min of metabolic inhibition. It was concluded that cardioplegia has an apparent detrimental effect on neonatal cardiomyocytes accumulation of 99mTc-sestamibi during recovery from an ischaemic-like insult.     

Role of potassium concentration in cardioplegic solutions in mediating endothelial damage

We studied the effect of potassium concentration in cardioplegic solutions on endothelial function by examining its influence on 5-hydroxytryptamine- (5-HT) and nitroglycerin-induced vasodilation in the isolated rat heart. Forty-eight rat hearts were perfused on a modified Langendorff preparation. After a baseline record of increase in coronary flow induced by 10(-7) M 5-HT and 10 micrograms/mL nitroglycerin, the hearts were perfused for 30 or 60 minutes with either St. Thomas' solution or Bretschneider solution containing 20 mmol/L of potassium or for 30 minutes with either solution containing 30 mmol/L of potassium (n = 8 in each). Initially, 5-HT and nitroglycerin caused a 39.0% +/- 3.3% and 39.7% +/- 2.8% increase in coronary flow, respectively. After 30 or 60 minutes' perfusion with St. Thomas' solution containing 20 mmol/L of potassium, there was little change in the response to 5-HT or nitroglycerin (5-HT, 43.1% +/- 4.1%; nitroglycerin, 38% +/- 3.2%). Similarly, perfusion with Bretschneider solution (20 mmol/L K+) for 30 or 60 minutes did not alter the degree of vasodilation (5-HT, 39.2% +/- 2.9%; nitroglycerin, 38.0% +/- 3.3%). However, perfusion with St. Thomas' solution containing 30 mmol/L of potassium for 30 minutes abolished the endothelial-dependent 5-HT-induced vasodilation (5-HT, -1.6% +/- 1.4%; nitroglycerin, 36.9% +/- 2.2%). Perfusion with Bretschneider solution (30 mmol/L K+) gave similar results (5-HT, -2.1% +/- 1.2%; nitroglycerin, 36.4% +/- 1.7%). We conclude that the concentration of potassium in cardioplegic solutions plays a critical role in causing functional endothelial damage.     

The effectiveness of University of Wisconsin solution on prolonged myocardial protection as assessed by phosphorus 31-nuclear magnetic resonance spectroscopy and functional recovery.

The effectiveness of the University of Wisconsin solution on extended myocardial preservation was examined in this study using phosphorus 31-nuclear magnetic resonance spectroscopy. Isolated perfused rat hearts were arrested and stored in four preservation solutions: group 1, modified Krebs-Henseleit solution; group 2, modified St. Thomas' Hospital solution; group 3, oxygenated modified St. Thomas' Hospital solution containing 11 mmol/L glucose; and group 4, University of Wisconsin solution. The changes in myocardial high energy phosphate profiles and the intracellular pH values were measured during 12 hours of cold (4 degrees C) global ischemia and 90 minutes of normothermic reperfusion. Following ischemia, the hearts were assessed for hemodynamic recovery and myocardial water content. During ischemia, adenosine triphosphate depletion was observed in all groups; however, after 5 hours of ischemia, the adenosine triphosphate levels were significantly higher in group 3 compared with the other groups (adenosine triphosphate levels at 6 hours in mumol/gm dry weight: group 3, 7.6; group 4, 3.2; group 2, < 1; p < 0.025). The tissue water content at the end of ischemia was lower with the University of Wisconsin solution compared with the modified St. Thomas' Hospital solution or the oxygenated modified St. Thomas' Hospital solution (in ml/gm dry weight: group 4, 3.0; group 2, 4.4; group 3, 3.9; p < 0.05). The adenosine triphosphate repletion during reperfusion was greater with the University of Wisconsin solution compared with the modified St. Thomas' Hospital solution or the oxygenated modified St. Thomas' Hospital solution (12 mumol/gm dry weight in group 4; 8.1 in group 2; 9.0 in group 3; p < 0.05). Similar findings were obtained for the recovery of left ventricular pressure (in percent of preischemic control: group 4, 70%; group 2, 42%; group 3, 52%; p < 0.01) and coronary flow (group 4, 61%; group 2, 49%; group 3, 49%; p < 0.05). These data suggest that preservation with the University of Wisconsin solution affords improved hemodynamic recovery, enhanced adenosine triphosphate repletion, and reduced tissue edema upon reperfusion; however, oxygenated St. Thomas' Hospital solution with glucose is associated with the preservation of higher myocardial adenosine triphosphate levels during prolonged cold global ischemia. In conclusion, these data indicate that the University of Wisconsin solution might improve graft tolerance of ischemia in clinical heart transplantation.     

Effect of sodium aspartate on the recovery of the rat heart from long-term hypothermic storage.

We have investigated the reported ability of aspartate to enhance greatly the cardioprotective properties of the St. Thomas' Hospital cardioplegic solution after prolonged hypothermic storage. Rat hearts (n = 8 per group) were excised and subjected to immediate arrest with St. Thomas' Hospital cardioplegic solution (2 minutes at 4 degrees C) with or without addition of monosodium aspartate (20 mmol/L). The hearts were then immersed in the same solution for 8 hours (4 degrees C) before heterotopic transplantation into the abdomen of homozygous rats and reperfusion in vivo for 24 hours. The hearts were then excised and perfused in the Langendorff mode (20 minutes). Addition of aspartate to St. Thomas' Hospital cardioplegic solution gave a small but significant improvement in left ventricular developed pressure, which recovered to 82 +/- 3 mm Hg compared with 70 +/- 2 mm Hg in control hearts (p less than 0.05). However, coronary flow and high-energy phosphate content were similar in both groups. In subsequent experiments hearts (n = 8 per group) were excised, arrested (2 minutes at 4 degrees C) with St. Thomas' Hospital cardioplegic solution containing a 0, 5, 10, 20, 30, 40, or 50 mmol/L concentration of aspartate, stored for 8 hours at 4 degrees C, and then reperfused for 35 minutes. A bell-shaped dose-response curve was obtained, with maximum recovery in the 20 mmol/L aspartate group (cardiac output, 48 +/- 5 ml/min versus 32 +/- 5 ml/min in the aspartate-free control group; p less than 0.05). However, additional experiments showed that a comparable improvement could be achieved simply by increasing the sodium concentration of St. Thomas' Hospital cardioplegic solution by 20 mmol/L. Similarly, if sodium aspartate (20 mmol/L) was added and the sodium content of the St. Thomas' Hospital cardioplegic solution reduced by 20 mmol/L, no significant protection was observed when recovery was compared with that of unmodified St. Thomas' Hospital cardioplegic solution alone. In still further studies, hearts (n = 8 per group) were perfused in the working mode at either high (greater than 80 ml/min) or low (less than 50 ml/min) left atrial filling rates. Under these conditions, if functional recovery was expressed as a percentage of preischemic function, artifactually high recoveries could be obtained in the low-filling-rate group. In conclusion, assessment of the protective properties of organic additives to cardioplegic solutions requires careful consideration of (1) the consequences of coincident changes in ionic composition and (2) the characteristics of the model used for assessment.     

A comparison of UW cold storage solution and St. Thomas' solution II: a 31P NMR and functional study of isolated porcine hearts.

Although University of Wisconsin cold storage solution provides excellent preservation for the pancreas, the kidney, and the liver after extended cold ischemic storage, its ability to preserve the heart for extended cold storage periods is not yet proved. This study was carried out to evaluate the effect of University of Wisconsin solution on heart preservation and to compare it to modified St. Thomas' solution II with respect to the capacity to preserve high-energy phosphates and contractile function in pig hearts. Hearts were arrested with either University of Wisconsin cold storage solution or St. Thomas' solution II (10 ml/kg) and kept ischemic at 12 degrees C or 4 degrees C for 8 hours. Functional recovery after the preservation period was assessed by means of ventricular function curves of the isovolumically contracting Langendorff model perfused with modified Krebs-Henseleit solution. Phosphorus 31 nuclear magnetic resonance spectroscopy was used to monitor high-energy phosphates and intracellular pH during preservation and reperfusion. At 12 degrees C, hearts arrested and preserved with University of Wisconsin solution showed a rapid decrease in phosphocreatine and adenosine triphosphate. With St. Thomas' solution, phosphocreatine and adenosine triphosphate decreased slowly. Functional recovery was poorer with University of Wisconsin solution than with St. Thomas' solution. Hearts preserved at 4 degrees C with either solution showed no significant differences in high-energy phosphate content and functional recovery. Rigorous control of the low temperature (4 degrees C) is necessary when University of Wisconsin solution is used for heart preservation.     

Comparison of the protective properties of four clinical crystalloid cardioplegic solutions in the rat heart

Although few surgeons dispute the benefits of high-potassium crystalloid cardioplegia, objective comparison of the efficacy of various formulations is difficult in clinical practice. We compared four commonly used cardioplegic solutions in the isolated rat heart (N = 6 for each solution) subjected to 180 minutes of hypothermic (20 degrees C) ischemic arrest with multidose cardioplegia (3 minutes every half-hour). The clinical solutions studied were St. Thomas' Hospital solution, Tyers' solution, lactated Ringer's solution with added potassium, and a balanced saline solution with glucose and potassium. Postischemic recovery of function was expressed as a percentage of preischemic control values. Release of creatine kinase during reperfusion was measured as an additional index of protection. St. Thomas' Hospital solution provided almost complete recovery of all indexes of cardiac function following ischemia including 88.1 +/- 1.6% recovery of aortic flow, compared with poor recovery for the Tyers', lactated Ringer's, and balanced saline solutions (20.6 +/- 6.5%, 12.5 +/- 6.4%, and 9.6 +/- 4.2%, respectively) (p less than 0.001). Spontaneous defibrillation was rapid (less than 1 minute) and complete (100%) in all hearts in the St. Thomas' Hospital solution group, but much less satisfactory with the other formulations. Finally, St. Thomas' Hospital solution had a low postischemic level of creatine kinase leakage, contrasting with significantly higher enzyme release in the other solutions tested (p less than 0.001). Although differences in composition are subtle, all potassium crystalloid cardioplegic solutions are not alike in the myocardial protection they provide. Comparative studies under controlled conditions are important to define which formulation is superior for clinical application.     

Low-potassium University of Wisconsin solution for cardioplegia: improved protection of the isolated ischemic neonatal rabbit heart

Recovery of cardiac function and high-energy phosphates following ischemia and reperfusion were determined for hearts perfused with low potassium University of Wisconsin solution, high potassium University of Wisconsin solution, St Thomas' solution, or subjected to hypothermia alone. Isolated hearts were arrested for either 3 h at 15 degrees C or 6 h at 20 degrees C (n = 7 for each group) with one of the four solutions and then reperfused. Aortic flow after ischemic arrest at 20 degrees C was 40.3 +/- 13.3%, 79.3 +/- 10.0%, 64.3 +/- 11.9% and 43.9 +/- 15.9% of control values for high potassium University of Wisconsin solution, low potassium University of Wisconsin solution, St Thomas' solution and hypothermia alone, respectively. Similar results were observed in hearts subjected to ischemic arrest at 15 degrees C. Myocardial adenosine triphosphate and creatine phosphate after reperfusion tended to be higher in the low potassium University of Wisconsin solution group. It is concluded that low potassium University of Wisconsin solution may provide reliable cardioplegia during surgery that requires prolonged cardiac arrest in neonates and infants.     

Evaluation of a new preservative solution for cardiac graft during hypothermia.

BACKGROUND: Reports conflict on the beneficial effects of several cardioplegic solutions such as University of Wisconsin and St. Thomas' Hospital solutions. Therefore our objective was to assess the efficacy of several cardioplegic solutions for cardiac preservation by comparing University of Wisconsin modified solution (UW-1 and UW-1 + calcium = UW-2), St. Thomas' Hospital solution N degrees 1 (STH-1), Celsior solution, and a solution from our laboratory, Lyon preservation solution (LYPS). METHODS: We randomized male rats (n = 70) to 7 groups: LYPS, Celsior, STH-1, UW-1, UW-2, normal saline solution, and control. All hearts, except control hearts were preserved by cold storage (8 hours, 4 degrees C) in the various solutions. We used isolated non-working-heart preparations (left ventricular function evaluation, n = 5/group) or biopsy specimens (energetic store evaluation, n = 5/group) to assess quality of heart preservation. RESULTS: Hearts stored with the saline solution had a mean left ventricular developed pressure (LVDP) of 3.6 +/- 1.3 mm Hg. In contrast, LYPS and Celsior hearts had mean LVDP close to that of the control hearts (97 +/- 2.6, 92.1 +/- 2.2, and 122 +/- 1.9 mm Hg, respectively), whereas STH-1, UW-1, and UW-2 hearts presented an intermediate functional response (48 +/- 4, 39.9 +/- 4.1, and 69 +/- 1.8 mm Hg, respectively). The STH-1 and saline hearts showed increased release of creatine kinase (541.9 +/- 168 and 1,080.8 +/- 126.2 UI/liter, respectively). The energetic charge (EC = [(0.5 ADP + ATP)/ATP + ADP + AMP]) in Celsior, UW-2, and saline was significantly lower (p < 0.001) than in the other groups. CONCLUSION: The composition of the preservation solutions had a notable effect on myocardial viability. Our results indicated that LYPS and Celsior solutions had comparable efficacy for left ventricular function. However these solutions may offer better preservation than do UW-1, UW-2, or STH-1 solutions.     

Effect of oxygenation and consequent pH changes on the efficacy of St. Thomas' Hospital cardioplegic solution

The hypothesis tested is that shifts in pH, induced when a cardioplegic solution is oxygenated, can be detrimental. We added either 100% nitrogen, 95% nitrogen and 5% carbon dioxide, 100% oxygen, or 95% oxygen and 5% carbon dioxide to the cardioplegic solution (St. Thomas' Hospital No. 2 plus glucose 11 mmol/L), and determined postischemic recovery of isolated rat hearts after 3 hours of 10 degrees C cardioplegic protected ischemia. Hearts were arrested and reinfused every 30 minutes throughout the ischemic period with cardioplegic solution. When 5% carbon dioxide was added to nitrogen, the pH of the cardioplegic solution decreased from 9.1 (100% nitrogen) to 7.0 (95% nitrogen: 5% carbon dioxide), a change associated with improved postischemic functional recovery. Aortic output improved from 52.3% +/- 2.7% to 63.9% +/- 2.8%, p less than 0.05, and cardiac output from 60.8% +/- 3.6% to 75.4% +/- 3.3%, p less than 0.01. This improvement was associated with diminished efflux of lactate during ischemia but increased postischemic release of lactate dehydrogenase. When nitrogen was replaced with oxygen, the addition of 5% carbon dioxide resulted in a similar decrease of pH, which again was associated with improved postischemic functional recovery. Aortic output improved from 66.3% +/- 2.8% (100% oxygen) to 88.9% +/- 3.7% (95% oxygen: 5% carbon dioxide), p less than 0.005, and cardiac output from 75.3% +/- 4.1% to 88.9% +/- 2.4%, p less than 0.01. The efflux of lactate during ischemia and the postischemic release of lactate dehydrogenase were similar in both groups. Furthermore, provision of additional oxygen with perfluorocarbons in an electrolyte solution identical to the St. Thomas' Hospital plus glucose solution and oxygenated with 95% oxygen: 5% carbon dioxide conferred no extra protection. In conclusion, the St. Thomas' Hospital No. 2 plus glucose cardioplegic solution should be oxygenated but with 95% oxygen: 5% carbon dioxide and not 100% oxygen because of the additive effect of a relatively "acidotic" pH.     

Superior myocardial preservation with modified UW solution after prolonged ischemia in the rat heart

Cardiac transplantation remains constrained by poor graft tolerance of prolonged cold ischemia. University of Wisconsin solution has remarkably extended ischemic preservation in pancreas, kidney, and liver transplantation. To assess its efficacy in cardiac preservation, modified University of Wisconsin solution flush and storage were tested against St. Thomas' cardioplegia flush and normal saline solution storage after six hours of ischemia at 0 degrees C in 46 isolated rat hearts. After ischemia, groups were compared before and after reperfusion. After ischemia but before reperfusion, University of Wisconsin solution hearts had significantly less tissue water (3.8%), superior tissue sodium, potassium, calcium, and magnesium profiles, and elevated adenosine and inosine levels, and tended toward better histological preservation. After reperfusion, University of Wisconsin solution more effectively preserved left ventricular compliance (75% versus 35% of baseline), developed pressure (71% versus 45% of baseline), histological integrity, and tissue potassium and calcium profiles than St. Thomas' solution. The University of Wisconsin solution provided superior preservation of systolic and diastolic ventricular function, tissue histology, tissue water, and tissue electrolytes than did St. Thomas' cardioplegia and normal saline solution storage in this experimental model, and might result in improved graft tolerance of ischemia in clinical cardiac transplantation.     

A comparative study of the most widely used solutions for cardiac graft preservation during hypothermia.

BACKGROUND: Reports conflict on the benefits of preservative solutions. We investigated the efficacy of the most widely used cardioplegic solutions by comparing extracellular solutions such as Celsior solution, St. Thomas Hospital solutions 1 and 2 (STH-1, STH-2), the modified University of Wisconsin solution (UW-1), Lyon Preservation solution (LYPS) from our laboratory, and intracellular solutions such as standard University of Wisconsin solution (UW), Bretschneider solution (HTK), Stanford solution (STF), and Euro-Collins solution (EC). METHODS: Male rats (n = 110) were randomized into 11 groups: LYPS, Celsior, STH-1, STH-2, UW-1, UW, HTK, STF, EC, and normal saline solution groups, and a control group. All hearts, except controls, were preserved by cold storage (8 hours at 4 degrees C) in the various solutions. We used an isolated non-working-heart model and biopsy specimens to assess heart preservation (n = 5/group). RESULTS: Hearts stored in the EC and saline solutions had poor left ventricular developed pressure (LVDP) x heart rate (HR) (1,407.5 +/- 154 and 1,390 +/- 439 mm Hg/mn, respectively). In contrast, hearts stored in LYPS and Celsior had a LVDP x HR close to control hearts (31,349 +/- 1,847, 27,620 +/- 1,207, and 36,627 +/- 1,322 mm Hg/mn, respectively), whereas hearts stored in STH-1, STH-2, UW-1, UW, HTK, and STF had intermediate functional response (14,278 +/- 2,176, 12,402 +/- 1,571, 11,428 +/- 1,629, 11,603 +/- 2,521, 7,045 +/- 537, and 7,086 +/- 1,206 mm Hg/mn, respectively). Hearts preserved with STH-2, UW, HTK, STF, EC, and saline solution showed significantly increased release of creatine kinase and lactate dehydrogenase than did control hearts or hearts preserved in Celsior, LYPS, STH-1, and UW-1. The energetic charge (EC = [(0.5 adenosine diphosphate + adenosine triphosphate) / (adenosine triphosphate + adenosine diphosphate + adenosine monophosphate)]) in STH-2, UW, HTK, STF, EC, and saline groups was significantly lower (p < 0.05) than in the other groups. CONCLUSION: Extracellular-type solutions provided better preservation than did intracellular-type solutions. However, UW and UW-1 (intracellular- and extracellular-type solutions) provided equivalent preservation of cardiac function. Preservation quality may be attributed to calcium, often added to extracellular solutions. Among extracellular solutions, Celsior and LYPS solution showed comparable efficacy on left ventricular function and seemed to offer better preservation than the other solutions tested in this study.     

Comparison of three cardioplegic solutions during hypothermic ischemic arrest in neonatal blood-perfused rabbit hearts

Inadequate myocardial preservation continues to be an important cause of postoperative morbidity and mortality after pediatric cardiac operations. To investigate methods of improving preservation in neonatal myocardium, we compared three cardioplegic solutions with topical hypothermia during 120 minutes of ischemic arrest in isolated, blood-perfused, neonatal rabbit hearts. Topical hypothermia (15 degrees C) without cardioplegia resulted in 71% +/- 5% recovery of preischemic contractile function. A high potassium (30 mEq/L) cardioplegic solution resulted in a 76% +/- 6% recovery of function, not significantly different from that obtained with hypothermia alone. In contrast, the St. Thomas' Hospital and H?pital Lariboisiere cardioplegic solutions resulted in recoveries of 89% +/- 6% and 88% +/- 7%, respectively, both of which were significantly greater (p less than 0.001) than recoveries obtained with the high potassium solution or hypothermia alone. Thus the cardioplegic solutions used at St. Thomas' Hospital and H?pital Lariboisiere provided excellent protection during 2 hours of hypothermic ischemic arrest in neonatal rabbit hearts and resulted in functional recovery superior to that achieved with hypothermia alone or with the high potassium cardioplegic solution.     

Long-term preservation of explanted hearts perfused with L-aspartate-enriched cardioplegic solution. Improved function, metabolism, and ultrastructure.

The effects of supplementing oxygenated St. Thomas' Hospital cardioplegic solution No. 2 with L-aspartate and/or D-glucose for the long-term preservation of excised rat hearts were determined with isolated working heart preparations. Left ventricular function was assessed at 37 degrees C with a crystalloid perfusate, before cardioplegic arrest and after 20 hours of low-flow perfusion (1.5 ml/min) with continuing arrest at 4 degrees C, and after this period, again at 37 degrees C with a crystalloid perfusate. Four groups (n = 8/group) of hearts were studied with four cardioplegic solutions: St. Thomas' Hospital solution alone, St. Thomas' Hospital solution with aspartate 20 mmol/L, St. Thomas' Hospital solution with glucose 20 mmol/L, and St. Thomas' Hospital solution plus both aspartate and glucose (20 mmol/L each). The addition of glucose to St. Thomas' Hospital solution made no significant difference in the recovery of aortic flow rates (17.7% +/- 8.6% and 21.6% +/- 7.8% of prearrest values), but when aspartate or aspartate and glucose were present, hearts showed significant improvements (89.8% +/- 5.2% and 85.0% +/- 6.2%, respectively). These improvements were associated with a reduction in the decline of myocardial high-energy phosphates during reperfusion, a reduction in cellular uptake of Na+ and Ca++, and a reduction in ultrastructural damage. These results indicate that low-flow perfusion with St. Thomas' Hospital solution plus aspartate can considerably extend the duration of safe storage of explanted hearts.     

Adenosine and lidocaine: a new concept in nondepolarizing surgical myocardial arrest, protection, and preservation

OBJECTIVE: Depolarizing potassium cardioplegia has been increasingly linked to left ventricular dysfunction, arrhythmia, and microvascular damage. We tested a new polarizing normokalemic cardioplegic solution employing adenosine and lidocaine as the arresting, protecting, and preserving cardioprotective combination. Adenosine hyperpolarizes the myocyte by A1 receptor activation, and lidocaine blocks the sodium fast channels. METHODS: Isolated perfused rat hearts were switched from the working mode to the Langendorff (nonworking) mode and arrested for 30 minutes, 2 hours, or 4 hours with 200 micromol/L adenosine and 500 micromol/L lidocaine in Krebs-Henseleit buffer (10 mmol/L glucose, pH 7.7, at 37 degrees C) or modified St Thomas' Hospital solution no. 2, both delivered at 70 mm Hg and 37 degrees C (arrest temperature 22 degrees C to 35 degrees C). RESULTS: Adenosine and lidocaine hearts achieved faster mechanical arrest in (25 +/- 2 seconds, n = 23) compared with St Thomas' Hospital solution hearts (70 +/- 5 seconds, n = 24; P=.001). After 30 minutes of arrest, both groups developed comparable aortic flow at approximately 5 minutes of reperfusion. After 2 and 4 hours of arrest (cardioplegic solution delivered every 20 minutes for 2 minutes at 37 degrees C), only 50% (4 of 8) and 14% (1 of 7) of St Thomas' Hospital solution hearts recovered aortic flow, respectively. All adenosine and lidocaine hearts arrested for 2 hours (n = 7) and 4 hours (n = 9) recovered 70% to 80% of their prearrest aortic flows. Similarly, heart rate, systolic pressures, and rate-pressure products recovered to 85% to 100% and coronary flows recovered to 70% to 80% of prearrest values. Coronary vascular resistance during delivery of cardioplegic solution was significantly lower (P <.05) after 2 and 4 hours in hearts arrested with adenosine and lidocaine cardioplegic solution compared with hearts arrested with St Thomas' Hospital solution. CONCLUSIONS: We conclude that adenosine and lidocaine polarizing cardioplegic solution confers superior cardiac protection during arrest and recovery compared with hyperkalemic depolarizing St Thomas' Hospital cardioplegic solution.     

Superior protective effect of low-calcium, magnesium-free potassium cardioplegic solution on ischemic myocardium. Clinical study in comparison with St. Thomas' Hospital solution

The protective effect of low-calcium, magnesium-free potassium cardioplegic solution on ischemic myocardium has been assessed in adult patients undergoing heart operations. Postreperfusion recovery of cardiac function and electrical activity was evaluated in 34 patients; 16 received low-calcium, magnesium-free potassium cardioplegic solution (group I) and 18 received St. Thomas' Hospital solution, which is enriched with calcium and magnesium (group II). There were no significant differences between the two groups in age, sex, body weight, and New York Heart Association functional class. Aortic occlusion time (107.3 +/- 46.8 minutes versus 113.6 +/- 44.3 minutes), highest myocardial temperature during elective global ischemia (11.5 degrees C +/- 3.1 degrees C versus 9.3 degrees C +/- 3.2 degrees C), and total volume of cardioplegic solution (44.2 +/- 20.5 ml/kg versus 43.4 +/- 17.6 ml/kg) were also similar in the two groups. On reperfusion, electrical defibrillation was required in four cases (25.5%) in group I and in 15 cases (83.3%) in group II (p less than 0.005), and bradyarrhythmias were significantly more prevalent in group II (6.3% versus 44.4%; p less than 0.05). Serum creatine kinase MB activity at 15 minutes of reperfusion (12.3 +/- 17.0 IU/L versus 42.6 +/- 46.1 IU/L; p less than 0.05) and the dose of dopamine or dobutamine required during the early phase of reperfusion (1.8 +/- 2.5 micrograms/kg/min versus 6.1 +/- 3.3 micrograms/kg/min; p less than 0.0002) were both significantly greater in group II. Postischemic left ventricular function, as assessed by percent recovery of the left ventricular end-systolic pressure-volume relationship in patients who underwent aortic valve replacement alone, was significantly better in group I (160.4% +/- 45.5% versus 47.8% +/- 12.9%; p less than 0.05). Serum level of calcium and magnesium ions was significantly lower in group I. Thus low-calcium, magnesium-free potassium cardioplegic solution provided excellent protection of the ischemic heart, whereas St. Thomas' Hospital solution with calcium and magnesium enabled relatively poor functional and electrical recovery of the heart during the early reperfusion period. These results might be related to differing levels of extracellular calcium and magnesium on reperfusion.     

Creatine phosphate: an additive myocardial protective and antiarrhythmic agent in cardioplegia

The potential for enhancing myocardial protection by adding high-energy phosphates to cardioplegic solutions was investigated in a rat heart model of cardiopulmonary bypass and ischemic arrest. Creatine phosphate (CP) was evaluated as an additive to the St. Thomas' Hospital cardioplegic solution. Dose-response studies (CP 0 to 50 mmol/L) revealed 10.0 mmol/L as the optimal concentration which improved recovery of aortic flow and cardiac output after a 40 minute period of normothermic (37 degrees C) ischemic arrest from 21.2% +/- 5.4% and 32.8% +/- 4.6% in the CP-free control group to 82.5% +/- 3.7% and 82.6% +/- 4.2% (p less than 0.001), respectively. Creatine kinase (CK) leakage was reduced by 68.7% (p less than 0.001) in the CP group. With hypothermic (20 degrees C) ischemia (240 minutes) and multidose (every 30 minutes) cardioplegia, recoveries of aortic flow and cardiac output were improved from 33.1% +/- 8.4% and 42.2% +/- 7.7% in the CP-free control group to 77.9% +/- 4.2% and 79.6% +/- 4.3% (p less than 0.001), respectively, in the drug group. In addition to improving function and decreasing CK release, CP reduced reperfusion arrhythmias, significantly decreasing the time between cross-clamp removal and return of regular rhythm and also completely obviating the need for electrical defibrillation. 51Chromium-ethylenediaminetetraacetic acid (51Cr-EDTA), an extracellular space marker, was used to study the disappearance of CP from the cardioplegic solution during its stasis in the heart. Upon reperfusion, two thirds of the infused dose appeared unchanged in the coronary effluent; the remainder was either degraded or accumulated by the myocardium. Despite its alleged inability to enter the myocardial cell, exogenous CP exerts potent protective and antiarrhythmic effects when added to the St. Thomas' Hospital cardioplegic solution. Although the mechanism of action remains to be elucidated, it may involve binding or uptake of the drug.