Effects of Cardiomyoplasty on Cardiac Growth in Rats

A bstract Background and aim of the study : Cardiomyoplasty (CMP) has been proposed as a treatment for pediatric patients, but restriction of cardiac growth by the muscle wrap is a potential source of concern. This possibility was investigated in an immature animal model. Methods : Six-week-old rats (body weight 203.8 ± 5.4 g, mean ± SEM) underwent either left thoracotomy with CMP (group I, n = 7), or thoracotomy without CMP (group II, n = 8). A third group (group III, n = 7) served as untreated controls. Final measurements were made 20 weeks later after body weights had reached a plateau. Results : Preoperative body weights were not significantly different between the groups. At elective sacrifice, the body weights of animals that underwent surgery did not differ significantly (group I, 558.0 ± 21.5 g and group II, 617.3 ± 20.3 g), but were significantly less than those of control animals (727.6 ± 13.3 g, p < 0.001 and p < 0.01, respectively). Cardiac ventricular weights in the CMP group were significantly less than those of control animals (group I, 1.21 ± 0.06 g; group III 1.45 ± 0.04 g; p < 0.01), but were not statistically different from those of the sham thoracotomy group (group II, 1.36 ± 0.05 g). Mean left ventricular end-diastolic volumes were similar in all groups (group I, 0.67 ± 0.07 mL; group II, 0.66 ± 0.07 mL; and group III, 0.69 ± 0.10 mL; p = ns). Conclusions : A major surgical procedure impairs growth in juvenile rats. No evidence emerged from this study for additional restriction of cardiac development due to cardiac wrapping. However, studies that include stimulated muscle wraps are needed before CMP should be considered for the pediatric age group.