Gas exchange function one month after transplantation of lungs topically cooled for 2 hours in the non-heart-beating cadaver after failed resuscitation.

BACKGROUND: If lungs from subjects dying of heart attacks could be used for transplantation, the lung donor shortage could be radically reduced. The aim of this study was to investigate, in an experimental survival model, the results of lung transplantation using lungs from non-heart-beating donors. METHODS: The left lung, topically cooled to 25 degrees C for 2 hours in situ after 5 minutes of circulatory arrest and 26 minutes of unsuccessful cardiopulmonary resuscitation, was transplanted into a syngeneic rat. Five weeks after the transplantation, right pneumonectomy was performed and blood gases measured every 10 minutes for 1 hour. Comparison were made with two control groups, one where fresh donor lungs were transplanted and another where only right pneumonectomy was done. RESULTS: All animals survived and were in good condition at the end of the observation period. There was no statistically significant difference in arterial oxygen or carbon dioxide tension between the groups. The bronchial anastomoses showed normal healing in all cases. CONCLUSION: Lungs from non-heart-beating donors topically cooled in situ to 25 degrees C for 2 hours before being harvested showed excellent gas exchange and bronchial healing 5 weeks after transplantation.

Vascular function in the cadaver up to six hours after cardiac arrest.

BACKGROUND: The aim of the study was to evaluate how well vascular function is retained in a cadaver kept in a room with a temperature of 21 degrees C. METHODS: The aorta and pulmonary artery of rats were investigated in organ baths as fresh controls and after 1, 2, 3, or 6 hours' storage in the cadaver. Six-hour-old cadaver aortas were transplanted and investigated after 24 hours and 60 days. RESULTS: After 3 hours' storage there was no significant decrease in smooth muscle contractile function in either aorta or pulmonary artery. After 6 hours' storage both the aorta and the pulmonary artery demonstrated a significant decrease in smooth muscle contractile function, 30% (p < 0.05) and 44% (p < 0.001), respectively, compared to fresh controls. Storing the aorta for 2 hours and the pulmonary artery for 6 hours caused no significant decrease in endothelium-dependent relaxing function. In aorta segments investigated after 3 and 6 hours there was a significant decrease in endothelium-dependent relaxation, 12% (p < 0.05) and 29% (p < 0.001), respectively. Six-hour-old cadaver aortas transplanted and investigated after 24 hours or 60 days demonstrated no significant changes in endothelium-dependent relaxation and smooth muscle function compared to fresh controls. CONCLUSION: The pulmonary artery can tolerate 3 hours of warm ischemia in the nonheart-beating cadaver without loss of endothelium-dependent relaxation and smooth muscle function. The dysfunction seen in 6-hour-old cadaver aortas was normalized after transplantation and 24 hours of reperfusion.

Bronchial healing, lung parenchymal histology, and blood gases one month after transplantation of lungs topically cooled for 2 hours in the non-heart-beating cadaver.

BACKGROUND: The aim of this study was to investigate, in an experimental survival model, the functional and morphologic results of lung transplantation using lungs from non-heart-beating donors. METHODS: Left lungs, topically cooled to 25 degrees C for 2 hours in situ after 5 minutes of circulatory arrest followed by 26 minutes of unsuccessful cardiopulmonary resuscitation, were transplanted into syngeneic rats. Five weeks after the transplantation, right pneumonectomy was performed and blood gases measured after 60 minutes. In a control group, fresh donor lungs were used for transplantation and comparison was made with the cadaver group and a group of normal rats after right pneumonectomy. Morphologic changes were evaluated by semiquantitative scoring of 13 different parameters to obtain a total histologic index for each rat. RESULTS: Computerized tomography scans of the chest made during the third post-operative week showed normal lung parenchyma in both groups, and at 5 weeks there were no significant differences in blood gases. The bronchial anastomoses showed normal healing in all cases. The histologic changes in the lung parenchyma were generally mild and focal, primarily consisting of interstitial and perivascular mononuclear inflammation, bronchial inflammation and athelectasis. Surprisingly, the transplanted controls demonstrated the most pronounced changes, although only the difference in total histologic index between groups was significant. CONCLUSIONS: Lungs from non-heart-beating donors, topically cooled in the cadaver for two hours after failed resuscitation, showed normal bronchial healing and favorable parenchymal histology compared to transplanted control lungs 5 weeks after transplantation.

Effects of cardioplegic flushing, storage, and reperfusion on coronary circulation in the pig.

BACKGROUND: The aim of the study was to investigate how flush-perfusion of the heart with cold cardioplegic solution, 2 or 12 hours of cold ischemic storage, and 24 hours of reperfusion affect coronary endothelial function and coronary vascular resistance. METHODS: Porcine coronary arterial endothelial and smooth muscle function was studied in organ baths. An adult porcine working heart model was used to investigate coronary vascular resistance after 24 hours of reperfusion. RESULTS: Flushing the heart with 1 L of St. Thomas' cardioplegic solution, using a perfusion pressure of 60 to 65 mm Hg, significantly reduced endothelium-dependent relaxation. Flushing followed by 12 hours of storage gravely impaired endothelium-dependent relaxation, and 24 hours of reperfusion worsened it still more. CONCLUSIONS: Flushing the heart with cold cardioplegic solution impairs endothelium-dependent relaxation, as does prolonged cold ischemic storage. Reperfusion of injured coronary endothelium may injure it still more. A correlation was found (p < 0.001) between high coronary vascular resistance and low endothelium-dependent relaxation.

Effect of temperature in long-term preservation of vascular endothelial and smooth muscle function.

BACKGROUND: In clinical transplantation the donor organ is perfused with a cold preservation solution to obtain quick core cooling and a suitable environment for the tissue cells. Without good preservation of the vasculature, progressive deterioration of the blood flow during reperfusion may ultimately lead to the no-reflow phenomenon, even though the function of the other cells in the organ may be adequately preserved. The aim of this study was to find the optimal storage temperature for preservation of the vasculature. METHODS: The infrarenal aorta of 126 Sprague-Dawley rats were studied in organ baths: as fresh controls, after 36 hours of storage at 0.5 degrees C, 4 degrees C, 8.5 degrees C, and 22 degrees C in University of Wisconsin solution, and after 36-hour storage followed by transplantation and a lapse of 2 hours, 24 hours, and 7 days. The thromboxane analogue U-46619 was used to test contractility. Acetylcholine was used to elicit endothelium-dependent relaxation (EDR), and papaverine to elicit endothelium-independent relaxation. RESULTS: Storing the vessels at 0.5 degree C proved best regarding preservation of contractility, with a nonsignificant decrease, whereas storage at 4 degrees C and 8.5 degrees C resulted in a significant decrease after 36 hours. The contractility did not recover within 24 hours of in vivo reperfusion, but full recovery was seen after 7 days. Regardless of the preservation temperature used, a significant impairment in EDR was seen after 36 hours of storage. Two hours after transplantation, vessels stored at 4 degrees C and 8.5 degrees C showed no significant impairment in EDR, whereas those stored at 0.5 degrees C demonstrated a significant loss of EDR. After 24 hours and after 7 days, EDR was normal in all groups. CONCLUSIONS: Endothelium-dependent relaxing factor function is best preserved at 4 degrees C and 8.5 degrees C, whereas preservation of vascular smooth muscle function is best preserved at 0.5 degrees C.

Effect of flush-perfusion on vascular endothelial and smooth muscle function.

BACKGROUND: The aim of this study was to investigate how much perfusion pressure an artery can tolerate without significant loss of endothelium-dependent relaxation (EDR) and vascular contractility. METHODS: The abdominal aortas of 396 Sprague-Dawley rats were used. One hundred twenty aortas were flush-perfused for 1 or 5 minutes with cold St. Thomas' Hospital cardioplegic (STHC) solution or with the same solution but modified by the addition of 3.5% dextran 40. Three perfusion pressures were tested: 50, 100, and 150 mm Hg. Two hundred eighty vessels were subjected to pressures of 50, 150, or 300 mm Hg using saline or STHC solution at 22 degrees C or STHC solution at 4 degrees C, for 10 or 60 seconds. The vessels were investigated in organ baths. Contractility was tested with the thromboxane analogue U-46619, acetylcholine was used to investigate EDR, and papaverine to elicit endothelium-independent relaxation. RESULTS: Flush-perfusion with cold STHC solution for 5 minutes at a perfusion pressure of 50 or 100 mm Hg affected neither contractility nor EDR. Vessels exposed to a flush-perfusion pressure of 150 mm Hg for 1 or 5 minutes lost 39% (p < 0.001) and 53% (p < 0.001) of their contractility, respectively. Flush-perfusion at 150 mm Hg for 1 minute did not affect EDR, whereas 5 minutes' perfusion caused a reduction of 7% (p < 0.05). A repetition of these experiments using STHC solution with 3.5% dextran 40 added gave no significantly different results. The impairment in contractility and EDR seen after perfusion at 150 mm Hg for 5 minutes disappeared after transplantation and reperfusion for 7 days. The vessels could be distended with saline or STHC solution at a pressure of 150 mm Hg without affecting contractility at 22 degrees C. At 4 degrees C, however, this pressure was harmful to contractility. Distention at a pressure of 300 mm Hg almost abolished contractility and 7 days after transplantation there had not yet been any recovery of contractility, but 30 days after transplantation the grafts had regained their normal contractility. CONCLUSIONS: Cold STHC solution, with or without dextran 40, can be used with a perfusion pressure of 100 but not 150 mm Hg without impairing EDR or vascular smooth muscle function.

Successful transplantation of lungs topically cooled in the non-heart-beating donor for 6 hours.

BACKGROUND: The aim of this study was to transplant lungs that had been topically cooled in the non-heart-beating donor for 6 hours, using the most challenging evaluation method possible, namely single-lung transplantation followed by immediate contralateral pneumonectomy. METHODS: Domestic pigs were used (6 donors and 6 recipients) with a mean body weight of 59 +/- 3 kg. Ventricular fibrillation was induced, and after 1 minute, cardiac massage was started and heparin (5 mg/kg body weight) was given via a central venous catheter. Cardiac massage was continued for 10 minutes, during which the pig was ventilated with 50% oxygen. The pleural cavities were opened and the tracheal tube disconnected from the ventilator, with the result that both lungs deflated. Saline slush was placed in both pleural cavities so that it completely covered the lungs. Within 40 minutes the lung core temperature was less than 10 degrees C, and it was kept around 8 degrees C for 6 hours by adjusting the amounts of ice slush. The left lung was then harvested and transplanted into a prepared recipient, followed by right pneumonectomy within 46 +/- 4 minutes, thus making the recipient pig 100% dependent on the transplanted cadaver lung. RESULTS: The mean ischemic time for the cadaver lungs was 8 hours and 2 minutes (range, 7 hours and 25 minutes to 8 hours and 59 minutes). All animals remained in excellent condition throughout the 24-hour observation period, with arterial oxygen tensions of approximately 225 mm Hg, or 30 kPa (inspired oxygen fraction, 0.5). CONCLUSIONS: Lungs from non-heart-beating donors may be used for transplantation if heparinization and topical cooling can be initiated within minutes of irreversible cardiac arrest.

Addition of calcium to Euro-Collins solution is essential for 24-hour preservation of the vasculature.

BACKGROUND: Genuine Euro-Collins solution is calcium free. The aim of this study was to investigate whether the addition of calcium would improve its capacity to preserve the vasculature. METHODS: The infrarenal aorta of Sprague-Dawley rats was investigated in organ baths: as fresh controls, after 24 hours of cold (4 degrees C) storage in Euro-Collins solution, or in Euro-Collins solution with the addition of calcium in amounts ranging from 0.05 to 1.5 mmol/L. The thromboxane analogue U-46619 was used to investigate contractility. Endothelium-dependent relaxation was tested by cumulative addition of acetylcholine. Papaverine was used to elicit endothelium-independent relaxation. Investigation by transmission electron microscopy was also performed. RESULTS: Storage of rat aorta for 24 hours in genuine Euro-Collins solution almost abolished smooth muscle function, and severe edema was found in the endothelial cells. However, if calcium was added, the rat aorta could be stored for 24 hours without affecting smooth muscle function, and endothelium-dependent relaxation was only slightly reduced. Furthermore, only slight edema could be demonstrated in the endothelial cells. CONCLUSIONS: If calcium is added to Euro-Collins solution in amounts ranging from 0.4 to 1.5 mmol/L, it allows good preservation of rat aorta for 24 hours. Without calcium, this solution destroys both the function and morphology of the vessels.

Function of adult pig hearts after 2 and 12 hours of cold cardioplegic preservation.

BACKGROUND: Most cardioplegic solutions have been developed using the classic Langendorf heart perfusion model, which only allows a short experimental follow-up. Our aim was to investigate hearts after prolonged storage by using a physiologic model including prolonged perfusion with normal, fresh blood. METHODS: Sixteen hearts from 60-kg pigs were preserved with dextran-enriched (dextran-40, 35 g/L) St. Thomas' solution for 2 or 12 hours after which they were continuously reperfused for 12 hours with normal blood, supplied by a support pig. A flexible balloon, fixed to an artificial valve apparatus connected to a circuit system, was inserted in the left ventricle for obtaining measurements of hemodynamic performance. RESULTS: During the first 3 to 4 hours of reperfusion there was no significant difference in left ventricular developed pressure, cardiac output, minute work output, or oxygen consumption between the two groups. After this time left ventricular developed pressure (p < 0.001), cardiac output (p < 0.01), minute work output (p < 0.01), and oxygen consumption were significantly lower in the 12-hour group. Coronary flow was higher (p < 0.01) and coronary vascular resistance lower (p < 0.01) during the first 5 to 6 hours of reperfusion in the 12-hour group. After 12 hours of reperfusion coronary vascular resistance was significantly higher (p < 0.01) in the 12-hour group. CONCLUSIONS: High-degree and long-lasting coronary hyperemia at the beginning of reperfusion can be a sign of unsatisfactory preservation of the heart. This investigation shows the importance of reperfusion with normal blood and a long follow-up period after postischemic reperfusion when studying the effect of cardioplegic solutions.