We induced either ischemia or edema alone in isolated cardiomyocytes and whole Langendorff-perfused hearts. Function was measured as shortening dynamics and developed pressure, respectively.
Ischemic injury impaired function in both cardiomyocytes and whole hearts. Isolated cells showed significant reduction in peak shortening and departure and relaxation velocities. Whole hearts displayed severely reduced developed pressures. Hyposmotic solution forced cardiomyocytes to swell to 7 % greater than their normal size. No significant effect on shortening was seen. Similarly, Langendorff-perfused hearts were induced to take on 3 % more water than control-perfused hearts and 9 % more water than nonperfused hearts. This additional water was associated with mild dysfunction.
We demonstrate the capacity of the heart to tolerate edema greater than that seen in clinical settings without residual effect. Ischemia results in ongoing contractile dysfunction of both isolated cardiomyocytes and whole hearts. We conclude that dysfunction resulting from edema in ex vivo cardiac models is mild and suggest review of the importance given to edema-mediated dysfunction after cardiac surgery.