The effects of cardioplegia washout on myocardial preservation

Preservation of the myocardium in vitro is more effective than preservation in vitro when preservation conditions are apparently the same. The washout of cardioplegia from the myocardium by noncoronary blood flow has been implicated as a probable cause of the poorer myocardial preservation seen in vivo. Isolated dog hearts were used to study the effects of cardioplegia washout by low flow perfusion (0.05 ml/min/g LV weight) during a 2-hr preservation period. Six experimental groups of five hearts each underwent 2 hr of myocardial preservation at temperatures of 20 degrees C (three groups) or 30 degrees C (three groups). The three groups for each temperature consisted of retrograde coronary sinus perfusion (to simulate cardioplegia washout by collateral flow) with blood cardioplegia (BC), normal blood (NB), or no perfusion at all (No CSP). The quality of preservation in each group was assessed by measuring recovery of left ventricular function, tissue water and electrolyte content, and myocardial high-energy phosphate and adenylate content prior to, during, and following preservation. In hearts maintained at 20 degrees C, cardioplegia washout did not significantly affect left ventricular function or myocardial levels of H2O, Na, K, ATP, or total adenylates. When myocardial temperature was allowed to increase to 30 degrees C, preservation was better with low flow perfusion during the preservation period. Hearts warmed to 30 degrees C with no cardioplegia washout experienced a 50% loss of tissue ATP levels and recovered less than 30% of normal left ventricular function during a 150-min reperfusion period. In contrast, hearts slowly perfused during the preservation period maintained nearly normal levels of ATP and returned to normal function by 150 min of reperfusion. Although myocardial warming by noncoronary perfusion has a detrimental effect on myocardial preservation, the slow washout of cardioplegia per se has no apparent detrimental effect on preservation.     

Fructose-1,6-diphosphate and a glucose-free solution enhances functional recovery in hypothermic heart preservation.

BACKGROUND: Fructose-1,6-diphosphate (FDP) has been shown to protect tissue during hypoxia under various ischemic conditions, including isolated heart perfusion. We tested the hypothesis that adding FDP to St. Thomas solution can extend hypothermic heart preservation time. METHODS: Sixteen adult Sprague-Dawley rats were used. Under general anesthesia, the hearts were removed and preserved at 4 degrees C in St. Thomas solution (30 ml/kg) for 12 hours. FDP (5 mM) was added to the St. Thomas solution in the study group (n = 8), whereas no FDP was used in the control group (n = 10). The hearts were reperfused after 12 hours of preservation using a working heart model. RESULTS: In the study group, cardiac output ranged from 13.00 +/- 2.34 to 17.66 +/- 1.71 ml/min, maximum aortic flow was 3.40 +/- 1.99 to 9.26 +/- 1.72 ml/min, left ventricular stroke volume ranged from 0.074 +/- 0.014 to 0.092 +/- 0.009 ml, left ventricular stroke work ranged from 6.22 +/- 0.39 to 7.95 +/- 0.44 ml/mmHg, and maximum left ventricular generated power was 14.38 +/- 2.94 to 20.16 +/- 2.49 Joules/min. All of these parameters were higher than those in the control group (p < 0.001). Coronary vascular resistance and myocardial tissue wet/dry weight ratio were lower in the study group than in the control group (p < 0.05).CONCLUSIONS: Heart function was better preserved when FDP was added to St. Thomas solution during hypothermic rat heart preservation. The mechanism is not totally clear, but enhancement of high-energy phosphate production during ischemia is possible. Key words: heart, procurement, hypothermia, fructose-1,6-diphosphate.     

Beneficial effect of additional cardioplegia flush during hypothermic static cardiac preservation

BACKGROUND: The effects of various preservative solutions and methods have been studied to prolong the safety period of cardiac preservation. In this study, we used cardioplegic solution (CS) during cardiac preservation and investigated how flush CS yields good preservation of isolated hearts compared with only cold immersion. METHODS: Male Wistar rat hearts were arrested with 4 degrees C St. Thomas crystalloid CS. All hearts were immersed for 6 hr in a 4 degrees C Euro-Collins solution. Hearts were classified into seven groups by period and number of infusions of CS (20 ml/kg) during simple immersion of hearts. Infusion of CS during preservation was not used for group I. Infusion was performed at two hours after starting immersion for group II, at 3 hr for group III, at 4 hr for group IV, at 5 hr for group V, every hour for group VI, and every 2 hr for group VII. After preservation, the hearts were reperfused with blood using a support rat. Myocardial adenosine triphosphate was measured immediately after immersion of hearts. Biochemical examination of coronary effluents was performed at 15 min after reperfusion, and cardiac function was evaluated at 40 min after reperfusion. Myocardial specimens were subsequently taken for measurement of water content. RESULTS: Percentage recovery of left ventricular developed pressure and dp/dt in groups III, VI, and VII were higher than those in group I at each balloon volume, and left ventricular end-diastolic pressure in these groups was also significantly lower than that in group I. Levels of creatine kinase-MB and lactate in groups VI and VII after reperfusion were significantly lower than those in group I. Myocardial adenosine triphosphate was significantly better preserved in groups III, IV, VI, and VII than in group I. However, no significant difference in cardiac function or myocardial adenosine triphosphate was found among groups III, IV, VI, and VII. CONCLUSIONS: The use of CS during cardiac preservation is effective in preserving cardiac function and myocardial enzymes, and infusion may be sufficient if performed once-only at 3 or 4 hr from starting immersion in 6 hr storage of isolated rat hearts.     

The experimental study on long-term cardiac preservation: the efficacy of low-flow continuous perfusion with fluorocarbon

We compared the effect of simple immersion and continuous perfusion on long-term cardiac preservation, and evaluated the effectiveness of perfusion with oxygenated fluorocarbon solution. The isolated rabbit hearts were preserved for 24 hours at 4 degrees C using the following five preservation techniques: (1) simple immersion with Collins M solution (Group I), (2) perfusion with oxygenated Collins M solution at a flow rate of 10 ml/hr (Group II), (3) perfusion with the same solution as in Group II at a flow rate of 20 ml/hr (Group III), (4) perfusion with oxygenated Collins M solution containing 10% fluorocarbon at a flow rate of 10 ml/hr (Group IV), (5) perfusion with the same solution as in Group IV at a flow rate of 20 ml/hr (Group V). The hearts of Group I showed a significant decrease of myocardial ATP and an increase of myocardial lactate during preservation compared to the hearts of perfusion groups. Assessment of isovolumic left ventricular function following 24-hour preservation using a support animal showed a significant decrease of Max dp/dt and increase of end-diastolic pressure in the hearts of Group I. Perfusion with fluorocarbon (Group IV and V) significantly increased oxygen consumption compared to Group II and III in association with minimum accumulation of myocardial lactate, indicating that aerobic metabolism during preservation is better maintained in the fluorocarbon-perfused hearts. Moreover, CPK release and myocardial water gain during preservation were significantly less, and left ventricular function following preservation was significantly better in these hearts. Increasing the flow rate from 10 ml/hr to 20 ml/hr resulted in sustained increase in perfusion pressure (1.80 +/- 0.53 to 3.70 +/- 0.34 mmHg) and myocardial water content (79.2 +/- 0.4 to 87.2 +/- 0.3%) during preservation in the hearts of Group III, but it did not further improve left ventricular function despite significant enhancement of myocardial oxygen uptake in both Group III and V. These results suggest that hypothermic low-flow continuous perfusion with oxygenated Collins M solution is superior to simple immersion with the same solution for long-term cardiac preservation, and that the addition of fluorocarbon to the perfusate enhances the efficacy of such a perfusion.     

Prolonged preservation of cadaver heart with Belzer UW solution: 24-hour storage system for asphyxiated canine hearts

The efficacy of Belzer UW solution was compared to Collins' solution in the preservation of asphyxiated cadaver hearts in a canine model. Donor hearts were stored for 24 h: 2 h of in situ hypothermic (15 degrees C) coronary perfusion plus 22 h of simple immersion in ice-cold solution. Verapamil, propranolol and prostacyclin were used for myocytoprotection in both groups. After orthotopic transplantation, all animals were weaned off bypass without inotropic support. After 1 h, however, the cardiac output was significantly higher in the Belzer UW solution group (128 +/- 28 vs. 67 +/- 13 ml/kg/min, p less than 0.01).     

Reduced tolerance of global ischemia in the hypertrophied heart

OBJECTIVE: Reduced coronary reserve during reperfusion may cause postischemic diastolic dysfunction in pressure-overload-induced hypertrophy. We studied the effect of coronary flow regulation (simulated hyperemic or depressed flow) on postischemic cardiac function during reperfusion. METHODS: Left ventricular pressure overload was induced in 4-week-old rats by abdominal aortic constriction. At 6 weeks of age, isolated Langendorff-perfused hearts (perfusion pressures: 75 mmHg in controls and 110 mmHg in the aortic constriction group) were subjected to hypothermic global ischemia (15 degrees C, 210 min), followed by 2 types of coronary flow regulation during the initial 20 min of reperfusion--manipulated high flow in control hearts (group I), manipulated low flow in control hearts (group II), manipulated high flow in aortic constriction hearts (group III), and manipulated low flow in aortic constriction hearts (group IV) (n = 6/group), and then constant pressure perfusion during the subsequent 45 min of reperfusion. Cardiac function was measured using an isovolumic balloon in the pre- and postischemic periods. RESULTS: Aortic constriction hearts exhibited greater left ventricular end-diastolic pressure than did control hearts. The increase in left ventricular end-diastolic pressure did not differ between group I (3 +/- 2 mmHg) and group II (-1 +/- 1 mmHg) or between group III (29 +/- 5 mmHg) and group IV (30 +/- 6 mmHg). No difference was seen in postischemic recovery of left ventricular systolic pressure between high and low flow groups in control and aortic constriction hearts. CONCLUSION: Manipulations in coronary flow during reperfusion did not affect postischemic cardiac function in control or aortic constriction hearts, suggesting that depressed coronary flow during early reperfusion is not a primary cause of postischemic diastolic dysfunction in the hypertrophied myocardium.     

Prolonged myocardial protection with St. Thomas' Hospital solution and University of Wisconsin solution. The importance of preservation techniques.

The effectiveness of University of Wisconsin solution (UWS) and oxygenated St. Thomas' Hospital solution (STS) for prolonged myocardial protection was evaluated in isolated working rat hearts preserved for 12 h at 4 degrees C using three different preservation techniques: induction of cardiac arrest and subsequent hypothermic storage with STS (group 1, n = 9) or UWS (group 4, n = 9), intermittent coronary flush (every 90 min) with STS (group 2, n = 9) or UWS (group 5, n = 9), or continuous coronary perfusion with STS (group 2, n = 7) or UWS (group 6, n = 7) before 60 min of reperfusion. In the UWS preserved hearts, recovery of aortic flow was greater when the simple storage technique was employed compared to intermittent or continuous coronary perfusion (groups 5 and 6). In the STS preserved hearts, aortic flow recovery was superior when the intermittent perfusion technique was applied. The same pattern was observed with regard to recovery of left ventricular pressure. Lactate dehydrogenase release during reperfusion was significantly less pronounced in group 4 (UWS, single flush, simple storage) as compared to group 1 (STS, single flush and simple storage), whereas best preservation of myocardial high energy phosphates was observed when hearts were preserved with multiple dose cardioplegia using STS. Simple hypothermic storage with UWS affords the best functional recovery after prolonged myocardial ischemia in all groups. Repetitive or continuous application of this solution is detrimental, possibly due to potassium overloading. In STS treated groups, multiple dose application of oxygenated STS enhances functional and metabolic recovery compared to its single dose application.(ABSTRACT TRUNCATED AT 250 WORDS)     

The consequences of asanguineous versus sanguineous reperfusion after long-term preservation of the heart

We have used the heterotopically transplanted rat heart to investigate whether the nature (sanguineous or asanguineous) of the initial period of reperfusion after hypothermic cardioplegic storage influences the postischaemic recovery of the heart. Excised rat hearts were arrested by infusion (1 min at 25 degrees C followed by 2 min at 7.5 degrees C) with the St Thomas' Hospital cardioplegic solution, subjected to 4 h of storage at 7.5 degrees C and heterotopically transplanted over a fixed period of 45 min. Reperfusion was then carried out for 80 min according to one of the following protocols: 60 or 20 min of blood perfusion in situ followed by excision, and 20 or 60 min of in vitro perfusion with crystalloid solution (Groups I and II, respectively) or immediate excision and 80 min of crystalloid perfusion (Group III). Intraventricular balloons were used to define pressure-volume relationships at the end of the 80 min period of reperfusion. Tissue samples were then taken for assessment of water content, adenosine triphosphate (ATP) and creatine phosphate (CP) content. Mean left ventricular developed pressure (at a loading volume of 110 microliters) was 92 +/- 6, 79 +/- 6 and 51 +/- 6 mmHg in Groups I, II and III, respectively. Left ventricular end-diastolic pressure was lower in the initial blood reperfusion groups (25 +/- 4 and 21 +/- 3 mmHg in Group I and II, respectively, compared with 37 +/- 5 mmHg in Group III).(ABSTRACT TRUNCATED AT 250 WORDS)     

Ischemic preconditioning enhances donor lung preservation in the rabbit

Objective: Ischemic preconditioning achieved by brief periods of ischemia followed by reperfusion before a prolonged period of ischemia, is well known to reduce myocardial damage. We investigated whether ischemic preconditioning of the lung could also attenuate ischemia-reperfusion injury following pulmonary preservation. Methods: Transient ischemia of the right lung was achieved in rabbits (n=4 in each group) by occluding the main bronchus and pulmonary artery, followed by reperfusion according to a protocol that differed between study groups: group 1 (control), 45 min ventilation; group 2, 30 min ventilation, 5 min ischemia and 10 min reperfusion; group 3, three periods of 5 min ischemia and 10 min reperfusion; group 4, five periods of 3 min ischemia and 6 min reperfusion. Donor lungs were then flushed with a crystalloid solution followed by inflated storage at 37°C for 2 h. The function of the right lung was assessed during reperfusion for 2 h with homologous, diluted and deoxygenated blood in an isolated, pressure-limited, and room-air ventilated model. Results: Significant differences (P<0.0001) were observed between groups 1 and 2 vs. groups 3 and 4 in veno–arterial oxygen pressure gradient (29±6 and 24±6 mm Hg vs. 124±24 and 132±14 mm Hg, respectively), and in weight gain (88±13 and 98±13% vs. 44±9 and 29±3%, respectively) after 1 h of reperfusion, and in wet-to-dry weight ratio (15.5±1.5 and 14.3±0.4 vs. 10.1±1.6 and 9.0±0.8, respectively) at the end of reperfusion. No significant differences in any of these parameters were observed between group 1 vs. group 2 neither between group 3 vs. group 4. Conclusions: These data suggest: (1) That 15 min, but not 5 min of transient ischemia prior to pulmonary preservation can significantly reduce edema in the lung graft upon reperfusion, thus improving oxygenation capacity and (2) although not significant, this beneficial effect seems to be slightly better with more repetitive periods of transient ischemia. Further research is warranted to investigate whether ischemic preconditioning in the human organ donor may become a new strategy to protect lung tissue during a planned ischemic event as in pulmonary transplantation.     

Hemodynamic analysis of descending versus ascending aortomyoplasty, and comparison with intra-aortic balloon pump

Objective: Descending and ascending aortomyoplasty are two surgical procedures intended to induce hemodynamic benefits similar to those of the intra-aortic-balloon-pump (IABP). To date, there have been no studies comparing the two surgical techniques. The objective of this study was to compare coronary blood flow augmentation and afterload reduction as produced by descending and ascending aortomyoplasty counterpulsation Methods: Twenty-two mongrel dogs (18–35 kg) underwent IABP application (n=7), descending (n=8), or ascending (n=7) aortomyoplasty. Left anterior descending (LAD) coronary artery blood flow was measured using a Transonic Doppler flow probe. Left ventricular pressure as well as aortic pressures proximal and distal to either the aortomyoplasty site or the IABP position were monitored continuously. Results: Descending aortomyoplasty induced higher elevation in the LAD blood flow during assisted beats (27% from 10.8±4 to 13.8±6 ml/min, P<0.001) than that induced by either ascending aortomyoplasty (19% from 11.7±5 to 14±5 ml/min, P<0.001) or IABP counterpulsation (18% from 8.6±3 to 10.2±4 ml/min, P<0.001). Conversely, while ascending aortomyoplasty reduced the left ventricular end-diastolic pressure by 16% (from 60±18 to 50±22 mmHg, P<0.001), similar to the 16% after load reduction achieved by the IABP counterpulsation, descending aortomyoplasty failed to induce afterload reduction. Conclusions: Descending aortomyoplasty produces higher coronary blood flow augmentation than either ascending aortomyoplasty or IABP. However, afterload reduction comparable to that achieved by IABP was observed only with ascending aortomyoplasty and not with descending aortomyoplasty.     

Effect of initial reperfusion temperature on myocardial preservation

The effect of initial postischemic reperfusion temperature on myocardial preservation was studied in the isolated working rat heart model. After baseline measurement of aortic flow rate, coronary flow rate, and heart rate, 40 hearts were subjected to 60 minutes of ischemic arrest at 15 degrees C induced with a single dose of cold potassium cardioplegic solution. Hearts were then revived with a 10 minute period of nonworking reperfusion at 28 degrees, 31 degrees, 34 degrees, or 37 degrees C (10 hearts each), followed by 5 minutes of nonworking reperfusion at normothermia, followed by 30 minutes of working perfusion. Repeat measurements of function were obtained and postischemic release of creatine kinase into coronary effluent was determined. Recovery of aortic flow was significantly reduced at lower initial reperfusion temperatures (75% at 28 degrees C versus 88% at 37 degrees C) and the effect was approximately linear throughout the range studied (p less than 0.05). Release of creatine kinase into coronary effluent was greater at lower initial reperfusion temperatures (421 ImU/min/gm wet weight at 28 degrees C versus 115 ImU/min/gm wet weight at 37 degrees C), also in a linear manner (p less than 0.05). In this model, initial postischemic hypothermic reperfusion is deleterious to cellular integrity and functional recovery of the preserved myocardium. Studies in higher animals and humans are warranted to further evaluate the effect of initial reperfusion temperature on myocardial preservation.     

The initial rate of troponin I release post-reperfusion reflects the effectiveness of myocardial protection during cardiac allograft preservation

Objective: To determine if the initial rate of troponin I release post-reperfusion reflects the effectiveness of myocardial protection during cardiac allograft preservation. Methods: A porcine model of orthotopic heart transplantation was used. Data from two control groups (CON₄ and CON₁₄) and two treatment groups (CAR₄ and CAR₁₄) were analysed. Hearts in CON₄ (n=6) and CAR₄ (n=6) were subjected to 4 h of ischaemia while hearts in CON₁₄ (n=3) and CAR₁₄ (n=6) were subjected to 14 h of ischaemia. All hearts were arrested and stored in the same extracellular preservation solution. Both donor and recipient animals in the CAR₄ and CAR₁₄ groups received a single intravenous dose of cariporide (2 mg/kg), prior to explantation and reperfusion, respectively. Results: Mean (SEM) plasma troponin I levels (μg/ml) 3 h post-reperfusion were: CON₄ 210±52, CAR₄ 68±21, CON₁₄ 633±177, CAR₁₄ 346±93. On multiple linear regression analysis, the rate of troponin I release over the first 3 h post-reperfusion was significantly lower in hearts stored for 4 h compared to hearts stored for 14 h (P<0.0001) and in hearts treated with cariporide compared to control hearts (P=0.0017). Early graft function was superior in hearts treated with cariporide, when compared to control hearts stored for the same period of time. All of the CAR₁₄ hearts could be weaned from cardiopulmonary bypass whereas none of the CON₁₄ could be weaned (6/6 vs. 0/3; P=0.012). While all hearts stored for 4 h could be weaned, contractility, as measured by the preload recruitable stroke work (PRSW) relationship, was significantly better preserved in CAR₄ hearts than in CON₄ hearts (P<0.0001). Conclusions: The initial rate of troponin I release post-reperfusion is determined by the duration of cardiac allograft ischaemia. Altering the myocardial preservation strategy can reduce the rate of release. Such reductions are associated with improvements in early graft function. These findings validate the initial rate of troponin I release post-reperfusion as an end-point when comparing cardiac allograft preservation strategies. In addition, the present study provides indirect evidence that troponin I degradation during ischaemia-reperfusion is related to the accumulation of intracellular calcium.     

Perfusion preservation maintains myocardial ATP levels and reduces apoptosis in an ex vivo rat heart transplantation model

BACKGROUND: Machine perfusion preservation improves reperfusion function of many solid organs, compared with conventional storage, but has received limited clinical attention in preserving hearts for transplantation. We evaluated representative extracellular (Celsior) and intracellular (University of Wisconsion) storage solutions using static and perfusion protective strategies over a clinically relevant preservation period. METHODS: Rat hearts were preserved for 200 minutes by either static storage or perfusion preservation in Celsior or University of Wisconsin solutions. Three conditions were studied: conventional static storage; static storage using either solution with 5.5 mmol/L glucose added; and perfusion preservation using either solution with 5.5 mmol/L glucose added. Glucose was provided as U-13C-labeled glucose, and glycolysis and oxidative metabolism during preservation were quantified from incorporation of (13)C into glycolytic and tricarboxylic acid cycle intermediates. Adenosine triphosphate levels after preservation, and apoptosis and cardiac function after reperfusion were measured. RESULTS: Both perfusion preservation groups had higher myocardial oxygen consumption during storage and better early graft function, compared with static preservation groups (P < .05). Adenosine triphosphate levels were higher after storage in the perfusion groups (P < .01). Apoptosis was reduced in the perfusion groups (P < .01). Comparing perfusion groups, hearts preserved with Celsior had higher myocardial oxygen consumption and glucose utilization during perfusion storage and exhibited decreased reperfusion coronary vascular resistance and myocardial water content, compared with the UW perfusion group (P < .05). CONCLUSIONS: Perfusion preservation results in greater metabolism during storage and superior cardiac function with improved myocyte survival, compared with static storage. Extracellular preservation solutions appear more effective for perfusion preservation, possibly by augmenting cellular metabolism.     

Highly efficient ex vivo gene transfer to the transplanted heart by means of hypothermic perfusion with a low dose of adenoviral vector

BACKGROUND: Hypothermic conditions required for donor heart preservation may reduce gene-transfer efficiency. Experiments were designed to determine whether a perfusion technique could improve the efficiency of gene transfer to donor hearts. METHODS: An adenoviral vector encoding beta-galactosidase (3.5 x 10(8) plaque-forming units) was infused into explanted rat hearts under 4 conditions (each n = 6): (1) the virus was diluted in 350 microL of University of Wisconsin solution and infused as a high-pressure bolus into the coronary arteries of donor hearts through the aortic root; (2) the virus was diluted in 5 mL of University of Wisconsin solution and circulated by means of a peristaltic pump (flow, 0.75 mL/min) through the vasculature of the donor heart for 30 minutes; (3) 5 mL of viral solution was circulated as for group 2 for 15 minutes; and (4) 5 mL of viral solution was circulated for 5 minutes at a flow rate of 2.4 mL/min. Transduced hearts were transplanted into the abdomen of syngeneic rats, and transgene expression was assessed by means of immunoassay 4 days later. RESULTS: The median beta-galactosidase content was (1) 45.0 ng/mg protein (25th-75th percentile, 33-73 ng/mg), (2) 640 ng/mg protein (25th-75th percentile, 614-878 ng/mg), (3) 493.8 ng/mg protein (25th-75th percentile, 456-527 ng/mg), and (4) 503.3 ng/mg protein (25th-75th percentile, 475-562 ng/mg; P <.01 for group 2 vs group 1, and P <.05 for groups 3 and 4 vs group 1). Transgene expression was predominantly in myocytes and favored the subepicardial region of the right ventricle. CONCLUSION: Hypothermic perfusion of the donor heart with an adenoviral vector resulted in efficient transgene expression compared with that induced by a single bolus injection.     

Enhancement of hypothermic heart preservation with fructose 1, 6-diphosphate.

BACKGROUND: We hypothesized that the addition of fructose 1, 6-diphosphate (FDP) to a hypothermic heart preservation solution could improve metabolic recovery because it has several beneficial effects. MATERIALS AND METHODS: Twenty adult Sprague-Dawley rats were used to study hypothermic heart preservation. The hearts were removed under general anesthesia and preserved at 4 degrees C in Euro-Collins solution (30 ml/kg) for 8 h. In the study group (N = 10), FDP (5 mM) was added to the Euro-Collins solution. In the control group (N = 10), no FDP was added. Heart function was studied after preservation using a working heart model. The ability of various concentrations of fructose 1,6-phosphate to passively diffuse through an egg phosphatidylcholine multilamellar vesicle (MLV) membrane bilayer was examined. RESULTS: Cardiac output ranged from 17.0 +/- 1.9 to 24.9 +/- 1.6 ml/min in the study group vs 2.0 +/- 1.0-12.3 +/- 1.7 ml/min for controls, average aortic flow was 10. 8 +/- 1.4 ml/min in the study group vs -1.3 +/- 1.6 ml/min for controls, and maximum LV generated power was 22.8 +/- 1.7 J/min vs 10.1 +/- 1.6 J/min for controls. Coronary flow, left ventricular stroke volume and stroke work, and myocardial oxygen consumption were much higher in the study group than in the control group. Coronary vascular resistance was lower in the study group than in the control group. Electron microscopic study indicated that many myocytes displayed patches of swollen mitochondria in the control group, but was rarely observed in the study group. The addition of 50 mM FDP caused substantial changes in MLV permeability. No dose of sucrose buffers outside the vesicles resulted in a significant changes of MLV permeability. CONCLUSIONS: Our results indicate that the addition of FDP to Euro-Collins solution significantly improves hypothermic rat heart preservation, and FDP appeared to cross the membrane bilayer.     

The results of experimental study of six-hour heart-lung preservation by autoperfusion method--its evaluation of optimal conditions and lung function after preservation

Up to date, it has been reported that the maintenance of ideal function of the preserved lungs were much more difficult than that of the hearts in heart-lung preservation. In this communication the authors have reported the results of experimental study for optimal conditions for preserving better function of the lungs by autoperfusion method by means of heart-lung preparation using 43 dogs. In this study the conditions of the preservation were fixed as following: perfusing blood temperature 29 degrees C, blood flow 30 ml/kg/min., FiO2 30%, FiCO2 5%, tidal volume 15 ml/kg, ventilation rate 10/min., and PEEP 5 cmH2O. Glucose-Insulin-Potassium (0.03 gm., 0.05 U., 0.02 mEq/kg/hr. respectively) were administered continuously by an infusion pump. The results showed that extravascular lung water contents after 6 hours of preservation was 0.79 (mean) +/- 0.01 (SD), which was increased only 1% over than the control group: 0.78 +/- 0.01. There was no significant difference of static lung compliance in two groups: the preserved group was 0.47 +/- 0.02 ml/gm.cmH2O compared to 0.51 +/- 0.06 in the control group. These results suggest that the autoperfusion method on our preserving conditions seems to be very promising and very effective to keep much better condition of the lungs in heart-lung preservation.     

Experimental study on myocardial preservation by perfluorochemical "comparison of myocardial preservation effect between continuous perfusion and intermittent perfusion"

The effect of myocardial preservation with perfluorochemical as cardioplegic solution was studied with isolated canine hearts which was compared between intermittent coronary perfusion and continuous coronary perfusion. Intermittent perfusion group (group I) was infused every 30 minutes during 5 hours ischemia with oxygenated perfluorochemical at the amount of 10 ml/kg. Continuous perfusion group (group II) was infused continuously at the amount of 10 ml/kg/30 minutes. After 5 hours of ischemic time, total perfusion volume of both group were same 100 ml/kg. The comparison of myocardial preservation effect between group I and group II was examined with biochemical study, hemodynamic study and histological study. As a result, biochemical study such as GOT, CPK, and Lactate showed higher in group II than in group I, and value of catecholamine and adenylate levels in myocardial tissue showed higher in group I than in group II. In hemodynamic study, LVSW and LVEDP showed excellent value in group I, but never showed adequate function in group II at late working phase. On the other hand, LVmax dp/dt was recovered excellently in group I but in group II was not recovered at early working phase. In histological findings with electronic microscopy, there were some limited ischemic lesion in group II, which was suggested disturbance of micro circulation. It may be attributable to low perfusion pressure of continuous perfusion method. Finally, with regard to SOD (Super oxide dismutase) consumption, group I took higher than group II, and also oxygen consumption. It shows that in group I there is an effective activity of aerobic metabolism during ischemia, which explain not only the improved functional recovery but also generation of free radical, caused by super oxide etc. It is concluded from these results that intermittent perfusion has provided excellent preservation against myocardial ischemia, and also has possibility of danger to set up reperfusion injury.     

速尿对改善供心保存的作用

目的研究在冷缺血期供心保存液中速尿对改善鼠心保存效果的影响。方法Ｓｔ．Ｔｈｏｍａｓ液中加入速尿（５０ｍｇ／Ｌ）停搏并冷保存大鼠心脏６小时,利用离体鼠心非循环式Ｌａｎｇｅｎｄｏｒｆ灌流功能测定模型,测定心脏功能的恢复,检测心肌细胞ＡＴＰ和ＴＡＮ的含量等。结果加速尿组保存后的左心功能恢复明显优于不加速尿组,加速尿组保存后心肌细胞ＡＴＰ和ＴＡＮ的恢复率明显高于不加速尿组。结论保存液中的速尿能改善供心的保护效果     

Cardiac preservation by continuous perfusion of the University of Wisconsin solution.

Recent studies have shown that the University of Wisconsin (UW) solution may be superior to standard solutions in preserving the isolated heart before transplantation. The authors compared the UW solution with a modified Krebs-Henseleit solution in a continuous hypothermic coronary perfusion model. Hearts from mongrel dogs were rapidly excised after hyperkalemic arrest with standard cardioplegia and were mounted in a perfusion apparatus for 24 hours. Twelve hearts were perfused with the Belzer UW solution (group 1), and 15 hearts were perfused with a modified Krebs-Henseleit solution (group 2). The hearts were transplanted in a cross-circulation model, and parameters of function (developed pressure [dP] and rate of pressure development [+/- dP/dt]) were measured. Mean (+/- SEM) developed pressure was 80 +/- 7 mm Hg in group 1 and 56 +/- 9 mm Hg in group 2 (p less than 0.05). The +dP/dt was 1433 +/- 126 mm Hg/s in group 1 and 843 +/- 154 mm Hg/s in group 2 (p less than 0.005), and the -dP/dt was 958 +/- 110 mm Hg/s in group 1 and 676 +/- 106 mm Hg/s in group 2 (p less than 0.05). The UW-preserved hearts also required fewer defibrillations (0.75 +/- 0.13) to establish a stable rhythm than the control hearts (5.87 +/- 2.07, p less than or equal to 0.02). There were no significant differences in weight gain, coronary resistance or creatine phosphokinase levels between the two groups. The authors conclude that the UW solution provides better preservation of function than a modified Krebs-Henseleit solution for continuous coronary perfusion.     

Efficacy of initial controlled perfusion pressure for ischemia-reperfusion injury in a 24-hour preserved lung.

In lung transplantation, the safety period of the ischemic time of the graft is within 6 hours. Because of the problem of donor shortage, it is essential to extend the safety period of the preservation time of the donor lung. However, the longer the preservation time is, the more severe is the resulting ischemia-reperfusion injury. This study was designed to evaluate the efficacy of initial controlled perfusion pressure in the reduction of ischemia-reperfusion injury in a 24-hour preserved lung. Japanese white rabbit lungs were flushed with a low-potassium dextran solution (4C, 500 ml) after injection of prostaglandin E1 (20 microgram, bolus via PA) and submersed in the same solution for 24 hours at 4C. After preservation, the left lung was reperfused using an extracorporeal lung perfusion model which comprised of a closed circuit combined with a membrane deoxygenator. Assessment of lung function included gas analysis of influent and effluent blood and mean pulmonary artery perfusion pressure. Then the lung wet/dry weight ratio was calculated. In group I of the control group (n=6), the left lung was reperfused immediately following flushing (without preservation) at a flow rate of 50 ml/min for 60 minutes. In groups II and III, grafts were stored for 24 hours. In group II, grafts (n=6) were reperfused at a flow rate of 50 ml/min for 60 minutes. In group III (n =6), the flow rate was controlled by maintaining the perfusion pressure below 30 mmHg during the initial 5 minutes and was increased to 50 ml/min for the subsequent 60 minutes. In group II, the mean pulmonary artery pressure during perfusion increased rapidly, and oxygenation deteriorated. All grafts developed pulmonary edema within 12 minutes after reperfusion. Examination of the specimen revealed that the peripheral lung was not perfused. In group III, the mean pulmonary artery perfusion pressure was maintained below 30 mmHg, and oxygenation was preserved sufficiently throughout the experiment (delta PO2 > 100 mmHg) with no significant difference from control values. In conclusion, ischemia-reperfusion injury of the 24-hour preserved lung was attenuated prominently by controlling initial perfusion pressure for 5 minutes.