ABSTRACT 98

IMPROVEMENT IN VENTRICULAR SIZE AND FUNCTION IS SUSTAINED FOLLOWING DEVICE BASED LEFT VENTRICULAR SHAPE CHANGE IN A CANINE HEART FAILURE MODEL

K. Fukamachi, P.M. McCarthy, M. Takagaki, Y. Ochiai, T. Shiota, T. Tabata, K. Doi, Cleveland Clinic Foundation, Cleveland, OH; C. J. Schweich, Jr., T.J. Mortier, R.F. Schroeder, Myocor Inc., Plymouth, MN

OBJECTIVE: The purpose of this study was to determine improvement in left ventricular (LV) size and function following left ventricular shape change in a canine heart failure (HF) model.

METHODS:  HF was induced in 15 healthy dogs by rapid ventricular pacing (230 bpm) for an average of 26 days.  The eight dogs in the treatment group underwent surgical implantation of the Myocor Myosplint® to produce a calculated 20% decrease in wall stress by altering LV shape.  Seven dogs received a sham operation to serve as controls.  Baseline end diastolic and end systolic volumes (EDV, ESV), ejection fraction (EF) and stroke volume (SV) were measured by 3D echo prior to implantation.  After surgery, pacing was maintained at 190 bpm for an average of 28 days at which time 3D echo studies were repeated.  Heart rate (HR), cardiac output (CO) and aortic pressure (AoP) were also measured.

RESULTS: Comparing baseline and chronic values in the treated group, EDV (baseline: 90.4 ± 13.3, chronic: 67.9 ± 12.8 ml) and ESV (baseline: 73.0 ± 8.5, chronic: 41.9 ± 12.1 ml) were significantly lower and EF (baseline: 18.7 ± 5.3%, chronic: 38.8 ± 13.5%) was significantly higher (p<0.05, paired t-test).  SV also increased (baseline: 17.4 ± 6.2, chronic: 26.0 ± 9.8) but did not reach significance (p=.053).  No significant changes were seen in the control animals.  There were no significant differences between the groups in HR, CO, or AoP. 

CONCLUSIONS: Implantation of the Myocor Myosplint demonstrated an improvement in LV performance as a result of a significant reduction in ventricular volume and a significant increase in ejection fraction.