Combining cariporide with glyceryl trinitrate optimizes cardiac preservation during porcine heart transplantation

Sodium-hydrogen exchange inhibitors, such as cariporide, are potent cardioprotective agents, however, safety concerns have been raised about intravenously (i.v.) administered cariporide in humans. The aim of this study was to develop a preservation strategy that maintained cariporide's cardioprotective efficacy during heart transplantation while minimizing recipient exposure. We utilized a porcine model of orthotopic heart transplantation that incorporated donor brain death and 14 h static heart storage. Five groups were studied: control (CON), hearts stored in Celsior; CAR1, hearts stored in Celsior with donors and recipients receiving cariporide (2 mg/kg i.v.) prior to explantation and reperfusion, respectively; CAR2, hearts stored in Celsior supplemented with cariporide (10 mumol/L); GTN, hearts stored in Celsior supplemented with glyceryl trinitrate (GTN) (100 mg/L); and COMB, hearts stored in Celsior supplemented with cariporide (10 mumol/L) plus GTN (100 mg/L). A total of 5/5 CAR1 and 5/6 COMB recipients were weaned from cardiopulmonary bypass compared with 1/5 CON, 1/5 CAR2 and 0/5 GTN animals (p = 0.001). Hearts from the CAR1 and COMB groups demonstrated similar cardiac function and troponin release after transplantation. Supplementation of Celsior with cariporide plus GTN provided superior donor heart preservation to supplementation with either agent alone and equivalent preservation to that observed with systemic administration of cariporide to the donor and recipient.

ATP-sensitive potassium channel activation mimics the protective effect of ischaemic preconditioning in the rat isolated working heart after prolonged hypothermic storage

1. Ischaemic preconditioning (IP) can significantly reduce the extent of infarct size, contractile dysfunction and necrosis in hearts from a number of animal species. Activation of ATP-sensitive potassium channels has been implicated in this process. The aims of the present study were to determine the extent to which IP preserves haemodynamic function in the rat isolated working heart model after prolonged hypothermic storage and to examine the involvement of activation of potassium channels in this process. 2. Hearts from Wistar rats were perfused on a Langendorff apparatus. After stabilization in working mode, baseline measurements of heart rate, aortic flow, coronary flow and cardiac output were performed. Hearts were randomized to one of six treatment groups: (i) untreated control; (ii) IP; (iii) 3 min perfusion with 200 mumol/L pinacidil; (iv) pinacidil vehicle; (v) 3 min perfusion with 10 mumol/L glibenclamide before IP; and (vi) 3 min perfusion with glibenclamide then pinacidil. Hearts were stored in an extracellular-based preservation solution for 6 or 12 h at 2-3 degrees C, remounted on the perfusion apparatus, stabilized as before and then haemodynamic measurements were repeated, after which time heart water contents were determined. 3. Recovery of haemodynamic function was markedly enhanced in the IP and pinacidil-treated groups compared with untreated and vehicle controls. These beneficial effects were completely blocked by glibenclamide. These results suggest that strategies for activating potassium channels in donor hearts may protect organs during hypothermic storage prior to transplantation.

The nitric oxide donor, diethylamine NONOate, enhances preservation of the donor rat heart

BACKGROUND

Ischemia/reperfusion injury to transplanted organs may be associated with loss of endothelial release of nitric oxide. The aim of this study was to determine whether supplementation of an extracellular-based cardioplegic solution in routine clinical use at our institution with nitric oxide (as diethylamine NONOate) enhanced poststorage functionality of an isolated working heart model.

METHODS

Excised hearts were ligated to an aortic cannula and immediately perfused retrogradely with oxygenated Krebs solution at a hydrostatic pressure of 100 cm H2O at 37 degrees C. This preparation was then converted to a working system by switching the supply of perfusate from the aorta to a left atrial cannula at a filling pressure of 15 cm H2O. After a 1-minute stabilization period, baseline measurements of heart rate, aortic flow, coronary artery flow, and cardiac output were performed. Oxygenated cardioplegic solution (0.1 micromol/L), with or without NONOate, was then infused into the coronary circulation. Hearts were then stored in the same solutions for 6 or 12 hours at 2 degrees to 3 degrees C. The hearts were then remounted on the perfusion apparatus and reperfused as before, and hemodynamic measurements were repeated. Water content of the hearts were then determined.

RESULTS

Addition of the nitric oxide donor significantly improved all hemodynamic parameters measured after 12 hours storage and aortic flow at 6 hours storage compared with the untreated control groups. There was no significant difference between the water contents of the NONOate-treated and control groups.

CONCLUSIONS

The presence of the nitric oxide donor diethylamine NONOate was associated with significantly better preservation of coronary artery flow and cardiac function in the isolated rat heart after a 12-hour period of hypothermic storage and suggests a novel use for this family of compounds in the transplantation context.

Adjunctive use of inhaled nitric oxide during implantation of a left ventricular assist device

BACKGROUND

The aim of this study was to evaluate the efficacy of inhaled nitric oxide in the prevention and reversal of pulmonary hypertension during and after left ventricular assist device implantation.

METHODS

Inhaled nitric oxide (20 ppm) was administered to seven consecutive patients undergoing implantation of a left ventricular assist device at the time of implantation and for the first 24 hours after operation.

RESULTS

Withdrawal of inhaled nitric oxide at 24 hours after operation was associated with a significant rise in both the transpulmonary gradient (from 8+/-1 to 14+/-2 mm Hg, p < 0.01) and in pulmonary vascular resistance (from 110+/-19 to 196+/-32 dynes x sec x cm[-5], p < 0.01). In two patients, the rise in pulmonary vascular resistance resulted in a critical fall in left ventricular assist device flow and hemodynamic deterioration, necessitating urgent reinstitution of inhaled nitric oxide.

CONCLUSION

The administration of inhaled nitric oxide at the time of left ventricular assist device implantation prevents rises in pulmonary vascular resistance that in some patients result in critical reductions in left ventricular assist device flow. We suggest that inhaled nitric oxide is a useful adjunctive treatment that should be routinely available at the time of left ventricular assist device implantation.