Overview and future practice patterns in cardiac and pulmonary preservation

Does pediatric heart transplant survival differ with various cardiac preservation solutions?

BACKGROUND

Few studies directly compare outcomes between the most commonly used preservation solutions in pediatric heart transplantation in a large cohort of recipients. The purpose of this study is to investigate the effect of cardiac preservation solution on survival in pediatric heart transplant recipients.

METHODS

The United Network for Organ Sharing (UNOS) database was retrospectively reviewed from 01/2004-03/2018 for pediatric donor hearts. Saline, University of Wisconsin (UW), "cardioplegia," Celsior, and Custodiol preservation solutions were evaluated. The primary endpoints were recipient survival at 30 days, 1 year, and long term.

RESULTS

After exclusion criteria, 3012 recipients had preservation solution data available. The most common preservation solution used was UW in 1203 patients (40%), followed by Celsior in 542 (18%), cardioplegia in 461 (15%), saline in 408 (14%), and Custodiol in 398 (13%). Survival of recipients whose donor hearts were procured with UW was as follows: 97%-30 day, 92%-1 year; Celsior: 97%-30 day, 92%-1 year; cardioplegia: 97%-30 day, 91%-1 year; saline: 97%-30 day, 91%-1 year; and Custodiol: 96%-30 day and 92%-1 year. Analysis of Cox models for 30-day and long-term survival revealed no statistical differences when comparing UW to Celsior (p = .333), cardioplegia (p = .914), saline (p = .980), or Custodiol (p = .642) in adjusted models.

CONCLUSIONS

There were no significant differences in 30-day or 1-year survival detected between commonly used preservation solutions in the pediatric heart transplant population.

Oxidative Stress and Lung Ischemia-Reperfusion Injury

Ischemia-reperfusion (IR) injury is directly related to the formation of reactive oxygen species (ROS), endothelial cell injury, increased vascular permeability, and the activation of neutrophils and platelets, cytokines, and the complement system. Several studies have confirmed the destructiveness of the toxic oxygen metabolites produced and their role in the pathophysiology of different processes, such as oxygen poisoning, inflammation, and ischemic injury. Due to the different degrees of tissue damage resulting from the process of ischemia and subsequent reperfusion, several studies in animal models have focused on the prevention of IR injury and methods of lung protection. Lung IR injury has clinical relevance in the setting of lung transplantation and cardiopulmonary bypass, for which the consequences of IR injury may be devastating in critically ill patients.

Isolated heart perfusion according to Langendorff---still viable in the new millennium

The isolated perfused mammalian heart preparation was established in 1897 by Oscar Langendorff. The method was developed on the basis of the isolated perfused frog heart established by Elias Cyon at the Carl Ludwig Institute of Physiology in Leipzig, Germany in 1866. Observations made using both methods at the end of the 19th and at the beginning of the 20th century led to important discoveries, forming the basis for our understanding of heart physiology. This included the role of temperature, oxygen and calcium ions for heart contractile function, the origin of cardiac electrical activity in the atrium, the negative chronotropic effect of vagus stimulation and the chemical transmission of impulses in the vagus nerve by acetylcholine. Langendorff himself demonstrated that the heart receives its nutrients and oxygen from blood via the coronary arteries and that cardiac mechanical function is reflected by changes in the coronary circulation. The method underwent many modifications but its general principle remains the same today. Blood, or more commonly crystalloid perfusates, are delivered into the heart through a cannula inserted in the ascending aorta, either at constant pressure or constant flow. Retrograde flow in the aorta closes the leaflets of the aortic valve and as a consequence, the entire perfusate enters the coronary arteries via the ostia at the aortic root. After passing through the coronary circulation the perfusate drains into the right atrium via the coronary sinus. The simplicity of the isolated mammalian heart preparation, the broad spectrum of measurements which can be done using this method, its high reproducibility and relatively low cost make it a very useful tool in modern cardiovascular and pharmacological research, in spite of a few shortcomings. In the last decade the method has brought many important advances in many areas including ischemia-reperfusion injury, cell-based therapy and donor heart preservation for transplant.

Selected contribution: mechanisms that may stimulate the resolution of alveolar edema in the transplanted human lung

Pulmonary edema is common in organ donors and lung transplant recipients. Therefore, we assessed the responsiveness of human donor lungs to pharmacological agents that stimulate clearance of alveolar edema. Organ donors whose lungs were rejected for transplantation were studied. After resection, transport (4 degrees C), and rewarming (37 degrees C) of lungs, alveolar fluid clearance was measured with (n = 8 donors) or without (n = 23 donors) beta-adrenergic stimulation. Terbutaline-stimulated clearance (10(-4) M) was higher than unstimulated clearance (7.1 +/- 1.3 vs. 4.8 +/- 2.4%/h, P < 0.01). Second, we determined whether medications given to the organ donor were associated with the extent of pulmonary edema or the rate of alveolar fluid clearance in the harvested lung. Preharvest administration of dopamine in low to moderate doses was associated with faster alveolar fluid clearance (r = 0.62, P < 0.01). Preharvest administration of diuretics was associated with lower extravascular lung water-to-dry weight ratios. This study provides the first evidence that a beta(2)-adrenergic agonist stimulates alveolar fluid clearance in the human donor lung. Aerosolized beta(2)-adrenergic agonists may have therapeutic value for hastening the resolution of alveolar edema during the management of donors before resection of lungs for transplantation or in the posttransplant setting.