An isolated mammalian heart preparation capable of performing work for prolonged periods

Use of the Isolated Perfused Heart for Evaluation of Cardiac Toxicity

The isolated perfused rat heart model can be used to evaluate cardiotoxicity, and is especially useful in distinguishing direct vs indirect cardiac injury. Various perfusion systems can be used to characterize the pathophysiologic as well as morphologic changes induced by drugs or chemicals of interest. The isolated perfused heart was used in the studies described herein to characterize the mechanism of allylamine cardiotoxicity. Rat hearts were perfused with Krebs-Henseleit buffer containing 10 mm allylamine and a latex balloon was inserted into the left ventricle to monitor pressure. Coronary flow in hearts perfused with 10 mm allylamine was similar to control hearts at 5, 10, and 30 min, but was reduced by 1 hr (11.5 ± 0.6 ml/min/g wet heart weight vs 16.0 ± 0.7, p < 0.01). Peak left ventricular systolic pressure increased in hearts perfused with allylamine for 5 min (156 ± 8 mm Hg vs 103 ± 9, p < 0.01), but by 2 hr was decreased compared to controls (89 ± 6 vs 105 ± 5, p < 0.05). End diastolic pressure was markedly increased at 2 hr (58 ± 3 vs 4 ± 0.8, p < 0.01). Morphologically, allylamine perfused hearts exhibited significant contraction band changes as well as numerous cells with marked swelling of the sarcoplasmic reticulum. The findings in this study suggest that allylamine produces direct myocardial damage that appears to be independent of coronary flow. These studies demonstrate that the isolated perfused rat heart model can be used to evaluate mechanisms of acute cardiotoxicity.

Organ preservation: from the past to the future

Organ transplantation is the most effective therapy for patients with end-stage disease. Preservation solutions and techniques are crucial for donor organ quality, which is directly related to morbidity and survival after transplantation. Currently, static cold storage (SCS) is the standard method for organ preservation. However, preservation time with SCS is limited as prolonged cold storage increases the risk of early graft dysfunction that contributes to chronic complications. Furthermore, the growing demand for the use of marginal donor organs requires methods for organ assessment and repair. Machine perfusion has resurfaced and dominates current research on organ preservation. It is credited to its dynamic nature and physiological-like environment. The development of more sophisticated machine perfusion techniques and better perfusates may lead to organ repair/reconditioning. This review describes the history of organ preservation, summarizes the progresses that has been made to date, and discusses future directions for organ preservation.

Historical aspects of cardiopulmonary bypass: from antiquity to acceptance

Cardiopulmonary bypass has evolved from an extremely risky procedure into a safe systematic process, and is practiced daily in thousands of centers throughout the world. Numerous individuals, from diverse specialities, have contributed to the knowledge of the processes of extracorporeal flow. The developmental sequence of advances in cardiopulmonary bypass has been divided into three nonexclusive periods based on the major changes observed during the time: (1) a conceptual and developmental period, consisting of events that occurred before 1950; (2) an applied technological period, 1950 to 1970; and (3) a refinement period, 1970 to present. Within each time frame, the major findings regarding biological and technical challenges, extracorporeal device development, and applied clinical practice will be explored. Technological advances in cardiopulmonary bypass have permitted surgeons to treat patients with both congenital and acquired heart disease, and anesthesiologists to identify appropriate mixtures of treatment regimens, whereby the risks associated with managing this challenging patient population could be minimized.

Observations on the Heart-Lung Preparation in the Rat

A technique for producing and studying a heart-lung preparation in the rat is described. The relationship between filling pressure and cardiac output was found to remain constant for 60 to 90 minutes after the start of the extracorporeal circulation. The influence on this relationship of alterations in pulmonary ventilation, arterial pulse pressure, and heart rate has not been found to be critical. The mechanisms underlying deterioration of the preparation have been investigated, but no firm conclusions have been reached. Deterioration was not prevented by the introduction of fresh blood into the circulation. During prolonged experiments, the extracellular-fluid content of the heart was found to increase, the intracellular potassium was unaltered, and the intracellular sodium was reduced. Acute elevation of the sodium concentration in the circulating blood lowered, whereas potassium raised, the cardiac output for a given filling pressure. These opposing actions were found to summate. Slowing of the heart brought about by high concentrations of potassium was antagonized by sodium.