An ovine model of tachycardia-induced degenerative dilated cardiomyopathy and heart failure with prolonged onset

Background: The aim of this study was to develop a model of lone-term progressive heart failure (HF). Methods and Results: A cardiac output flowprobe was implanted on the pulmonary artery of 9 adult sheep weighing 40 to 50 kg. Rapid ventricular pacing for 21 days at 160 to 190 bpm (rate A) resulted in moderate HE Animals were then paced at 205 to 215 bpm (rate B) for 42 days (severe HF) and for 28 days at rate B (advanced HF). Data were collected at baseline and moderate, severe, and advanced HF during submaximal exercise testing and by transthoracic echocardiography in sinus rhythm. There were marked increases in left ventricular (LV) area, mitral valve regurgitation, and IN end-diastolic pressure and decreases in LV wall thickness, LV ejection fraction, positive and negative dP/dt(max), and positive (dP/dt(max))/P throughout the pacing protocol. Conclusions: This ovine HF model incorporates the progressive nature of human HF and allows examination of both structural changes and hemodynamic parameters of HF during and after exercise challenge.