Preparation of a skeletal muscle ventricle in sheep: Severe damage to the latissimus dorsi muscle due to mobilization before preconditioning

As part of a study examining the use of a skeletal muscle ventricle for car diac assistance in sheep, a new concept of muscle preconditioning was put i nto practice. We aimed to produce a latissimus dorsi muscle (LDM) capable o f performing chronic work immediately after the construction of a skeletal muscle ventricle. The left LDM was detached from the thoracic wall, divided longitudinally and reattached in situ to achieve vascular delay. The right LDM was left unaffected. Thereafter, preconditioning of both LDM was start ed according to the clinically approved stimulation protocol for cardiomyop lasty. Preconditioning of the unaffected right LDM in situ resulted in a co mplete muscle fiber transformation with no signs of degeneration or necrosi s. Mobilization of the left LDM before preconditioning led to a distinct da mage of the muscle. During conditioning, the increase in burst du ration fr om 2 to 3 im pulses in sheep A and from 3 to 5 impulses in sheep B resulted in a homogenous degeneration of the muscle fibers of the left LDM. Histomo rphological analysis showed a dramatic increase in the percent perimysial a nd endomysial connective tissue. The applied concept of muscle prefabricati on proved to be a failure. Muscle splitting and mobilization followed by va scular delay and in situ conditioning as a concept of muscle prefabrication should be strictly avoided. Copyright (C) 2000 S. Karger AG,Basel.