Latissimus Dorsi tetanic fusion frequency in clinical settings: Monitoring fast to slow muscle transformation during follow-up of Demand Dynamic Cardiomyoplasty

Limited systolic assistance by weak power of the Latissimus Dorsi Muscle (LDM) due to excessive slow speed of shortening have been considered a problem of Dynamic CardioMyoPlasty (DyCMP ) after its creation by Carpentier and Chachques. To improve systolic assistance, and to reduce potential muscular damage, we introduced the concept of activity-rest stimulation, to deliver fewer impulses per day than with the clinical standard protocol. This was achieved by providing the LD wrap with daily periods of rest (demand stimulation) based on a heart rate cut-off. We here review how the demand protocol was introduced in 4 patients from the beginning and in 10 patients which had previously undergone continuous stimulation DyCMP. These ten subjects, with no short-term to midterm prospect of heart transplantation, were switched to the demand stimulation for worsening of clinical conditions. Furthermore, we report how the long-term changes in the LDM in contraction speed had been monitored by Tetanic Fusion Frequency (TFF) analysis (Mechanographic interrogation). In the 10 subjects switched two years after continuous stimulation the TFF values were significantly higher (33 ± 8.0 versus 15.8 ±11Hz; p< 0.0001) than at the start of the demand protocol. Although the long-term survival in this small group is not comparable with the one of transplant patients, demand dynamic cardiomyoplasty showed encouraging results compared with classic cardiomyoplasty. Since heart transplantation after cardiomyoplasty procedure is still possible and feasible, the procedure could be revived as a biological bridge for persons in the transplant waiting list, in particular in those countries in which economic and cultural constrains strongly limit heart transplants.