Coronary oxygen persufflation for heart preservation in pigs: analyses of endothelium and myocytes.

BACKGROUND: Coronary oxygen persufflation (COP) has been shown to prolong heart preservation time up to 14 hr in a mature pig model, with excellent recovery after orthotopic transplantation. The aim of the present study was to assess the structural, metabolic, and functional myocardial and endothelial integrity after COP in mature pig hearts. METHODS: Cardioplegic arrest was induced by original crystalloid Bretschneider solution (HTK 3h, n=6), modified Bretschneider solution (mHTK+COP, n=6), or University of Wisconsin solution (UW+COP, n=6). Hearts were stored for 3 (HTK 3h) or 14 hr (mHTK+COP, UW+COP) at 0 degrees to 1 degrees C. In addition, COP hearts were persufflated. After heterotopic transplantation and reperfusion for 7 days, hearts were analyzed by light microscopy or electron microscopy for structural injuries. Endothelial function, cardiac enzymes, metabolic parameters, and myocardial water content (MWC) were determined. Six recipient hearts served as controls. RESULTS: Quantitative light microscopic analyses and semiquantitative electron microscopic analyses showed an equal amount of damage in all groups including HTK 3h hearts. No rejection was observed. Substance P induced an equal dilatation in all hearts. Serum levels of cardiac enzymes were similar in all groups, but energy-enriched phosphates were significantly reduced, and MWC was augmented in the HTK 3h hearts and in the UW+COP hearts, in contrast to the mHTK+COP transplants. CONCLUSIONS: The lack of structural defects related to the COP technique, similar endothelial function, and an even better metabolic state of the mHTK+COP hearts versus HTK 3h hearts demonstrate the efficacy of the COP technique for prolongation of myocardial preservation time up to 14 hr.

Maintenance of physiological coronary endothelial function after 3.3 h of hypothermic oxygen persufflation preservation and orthotopic transplantation of non-heart-beating donor hearts.

OBJECTIVE: The use of non-heart-beating donors (NHBD) might increase the number of grafts available for transplantation. Experiments on heart transplantation from NHBDs demonstrated the necessity for oxygenation during preservation to allow sufficient myocardial recovery. It has been shown that, after 16 min normothermic ischemia followed by 3.3-h hypothermic preservation, excellent myocardial and cardiovascular recovery is attained, if coronary oxygen persufflation (COP) is included in the preservation protocol. Here tests are presented on the recovery of coronary endothelium derived relaxation (EDR) of NHBD hearts after preservation including COP. METHODS: After 16 min normothermic ischemia, pig hearts were stored for 3.3 h at 0-1 degrees C in modified HTK plus COP (mBHTK+COP, n=6) or in two control groups without COP: (1) with mBHTK (n=6); and (2) with HTK (n=4). Following orthotopic transplantation and 3 h of reperfusion with full blood, coronary EDR was tested in vitro using Substance P (SP) under indomethacin for prostaglandin blockage. Additional tests were performed adding L-NIL to block the NO-production by iNOS or L-NNA to block total NO production. RESULTS: The EDR in percent of precontraction was 78 +/- 7% after mBHTK+COP and 77 +/- 20% (mBHTK) or 72 +/- 7% (HTK) in the controls without significant differences between the groups. Physiologic values of normal coronaries were 75 +/- 9%. L-NIL for blockage of NO-production by iNOS resulted in unchanged relaxations. After blockage of total NO production by L-NNA, the SP-induced dilation was significantly reduced to 58 +/- 8% (mBHTK+COP) and to 48 +/- 8% (mBHTK) or 55 +/- 13% (HTK) in the controls. CONCLUSIONS: Even after 16 min of warm ischemia followed by 3.3 h of preservation with gaseous oxygen persufflation, orthotopic transplantation, and reperfusion the endothelium derived coronary dilatation was unchanged from physiologic values and similar to the controls without COP. Blockage of NO production by L-NNA resulted in equal values of EDR with or without COP, while blockage of NO production by iNOS did not influence the EDR reaction. Thus COP preservation, which has been shown to allow excellent recovery of preserved NHBD hearts, caused no damage to the coronary EDR mechanisms.

Total recovery of heart grafts of non-heart-beating donors after 3 hours of hypothermic coronary oxygen persufflation preservation in an orthotopic pig transplantation model.

BACKGROUND: The coronary oxygen persufflation (COP) technique has been previously shown to allow prolonged heart preservation of 14 hr with optimal recovery in a pig model of orthotopic transplantation. This technique may be applicable to hearts grafted from non-heart-beating donors (NHBD). METHODS: Experiments were performed on pigs to test the effectiveness of oxygenated preservation, using COP for preservation of NHBD hearts. After 16 min of in situ normothermic ischemia, the hearts were flushed with histidine-tryptophan-ketoglutarate (HTK) solution or modified HTK solution (mBHTK) including 30 mmol/L 2,3-butanedione monoxime, 40 mg/L hyaluronidase,15 micromol/L adenosine, and 50 micromol/L calcium. Hearts were stored in the flush solutions for 3.3 hr or additionally persufflated with gaseous oxygen through the coronary arteries (COP) and transplanted orthotopically. RESULTS: Simple storage in HTK did not allow recovery of these hearts, whereas mBHTK storage resulted in improved function with 1.1 L/min cardiac output. The cardiac output reached 2.8 L/min (68% of normal values) with a left ventricular developed pressure of 101 mm Hg only after mBHTK+COP. Then the hearts were able to guarantee the circulation of the recipient for the test period after weaning from the heart-lung machine. CONCLUSIONS: Even in an NHBD with more than 15 min of in situ ischemia, the use of COP in combination with mBHTK solution for 3.3-hr storage of the heart allows excellent recovery of transplanted hearts and normal weaning from the heart-lung machine. This indicates that COP combined with mBHTK may be an optimal preservation technique for use with NHBD hearts.