Efficacy of the Acorn Cardiac Support Device in animals with heart failure secondary to high rate pacing.
OBJECTIVE
To utilise an ovine model of tachycardia induced progressive dilated cardiomyopathy and heart failure to investigate the efficacy of passive ventricular constraint with the Acorn cardiac support device as a heart failure treatment.


METHODS
(a) Moderate heart failure was produced in 16 sheep by pacing for 3 weeks. Half were implanted and half sham implanted with the CSD. Pacing continued at a higher rate for an additional 3 weeks. Cardiac function was assessed by echocardiography and manometry. (b) Moderate heart failure was produced (as above) in 27 sheep, 9 were implanted with CSD, pacing was restarted for 4 weeks, the initial CSD implants were terminated and another 9 animals were CSD implanted (severe heart failure), pacing was restarted in the remaining 18 animals for an additional 4 weeks (total 12 weeks) and then all animals were terminated. Cardiac function was assessed using echocardiography and treadmill exercise testing.


RESULTS
(a) After 6 weeks of rapid pacing CSD implant animals had significantly better cardiac function both when compared with pre implant values and with non-implanted animals at termination. (b) CSD implantation at both moderate and severe failure resulted in significant improvements in cardiac function both when compared with pre implant values and with non-implanted animals at termination. When compared to pre implant values the improvement was greatest in severe implant animals.


CONCLUSIONS
In this ovine model of tachycardia induced progressive heart failure, CSD implantation in either moderate or severe heart failure resulted in improved cardiac function, reduced left ventricular volume and mitral regurgitation both when compared with function at time of implant and with non implanted control animals.
Power
John M
JM
Department of Applied Cardiovascular Research, Baker Heart Research Institute, Melbourne, Australia.
Raman
Jai
J
Byrne
Melissa J
MJ
Alferness
Clif A
CA
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D004195:Disease Models, Animal; D006333:Heart Failure / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D006353:Heart-Assist Devices; D012720:Severity of Illness Index; D012756:Sheep; D017180:Tachycardia, Ventricular / Q000150:complications; D016896:Treatment Outcome; D020257:Ventricular Remodeling / Q000502:physiology