Introduction The purpose of the current study was to evaluate the safety of low voltage direct current (DC) electric stimulation and its angiogenesis effect in a rabbit myocardial infarction (MI) model with electrodes directly fixed on the epicardium.

Materials and methods 28 Japanese white rabbits were randomly divided into control and treatment groups with 14 rabbits in each group. MI was induced by left anterior descending (LAD) artery ligation. A pair of platinum electrodes was directly placed on the ambilateral epicardium next to the LAD artery. Low voltage DC electric stimulation (4.0 V/cm, 60 min/day) was given to the treatment group immediately following the surgery until the 4th week post-operation. Parameters including blood routine, biochemistry, cardio and respiratory, pathology and immunohistochemisty from both groups were monitored throughout the experiment. Capillary density was counted at the end of the experiment.

Results The overall mortality rate was 7.1%, pneumothorax rate was 3.6%, and the intraoperative arrhythmia rate was 7.1%. Transient hypotension, anaemia, leucocytosis, hypoxaemia and slight increase of the myocardium enzyme were observed in both control and treatment groups. Except minor inflammatory cell infiltration and mild hyperaemia, there was no other adverse response observed on the myocardium caused by electric thermal effect. The capillary density in the treatment group (140.7±21.5) was significantly higher than that of the control group (60.3±21.7) (p<0.001) at the end of the experiment.

Conclusion It is safe to apply low voltage DC electric stimulation to the MI rabbits in addition to promote the myocardium angiogenesis.