Effects of preconditioning protocols on canine latissimus dorsi muscle

ABSTRACT

This reporti is a review of numerous protocols that have been used for conditioning of the latissimus dorsi muscle (LDM) for use in cardiomyoplasty. In this study the LDM of mongrel dogs was freed stretched about 1.5 cm and the distal end sutured to the iliac crest. Eleven preconditioining protocols were undertaken using the following technique stretch, stretch + single pulse stimulation pulse stimulation 45-7--100/min, strech + single stimulation 70-90/min, transection of left teres major (TM), Ttransection + single stimulation 45-75-100/min, subscapularis nerve crush, subscapularis nerve crush + intercostal vessel cut + stimulation 45-70-100/min, subscapularis nerve crush + intercostal or 100/min. A variety of pacemakers were used. Upon sacrifice at 3,4,6,8,16 or 28 weeks, LDMs were removed, wighed and assessed hitologically. In all of the muscles that were subjected to eletrical stimulation alone, atrophy resulted. Our experiments using increased workload and electrical stimulation at variousrtes resulted in conversion of fast to slow fiber types and less fibrosis and adiposis than stimulation alone. Unless a means can be developed to avoid atrophy of the LDM when it is used in the cardiomyoplasty procedure, poor results may be anticipated from the operation.