Cardiac cryopreservation at subzero temperatures: Study of systolic and diastolic function

Background. We studied the alterations produced in left ventricular systoli c and diastolic function after applying a protocol of cryopreservation at s ubzero temperatures. Isolated rabbit hearts were used for the study with 5% polyethylene glycol (PM 4000) being the cryoprotective agent. Material and method. The cryoprotectant solution CP-16 was used on the expl anted heart in three phases: induction, storage and thawing. After 60 minut es at -1.6 degrees C and thawing at 2.7 degrees C/min, the heart was connec ted to a Langendorff system and perfused anterogradely with Krebs-Henseleit buffer. We analyzed the systolic and diastolic parameters before and after cryopreservation, thereby establishing a comparative statistical study. Results. Following cryopreservation we found a statistically significant in crease (p < 0.05) in the peak and developed pressure of the left ventricle with an upward, left displacement of the ventricular function curve. This i s indicative of improvement in systolic function. However, the diastolic fu nction showed worsening, with a statistically significant increase (p < 0.0 5) in mean stiffness, decrease in differential stiffness (p < 0.05) and upw ard, left displacement of the diastolic pressure-volume curve. Conclusions. On the basis of our results we concluded that: a) PM 4000 poly ethylene glycol maintains the heart biological viability during cryopreserv ation at subzero temperatures, and b) after an cryopreservation left ventri cular diastolic function worsens with an increase in systolic function.