Increased aortic impedance precedes peripheral vasoconstriction at the early stage of ventricular failure in the paced canine model

Abstract

Background. Aortic input impedance is altered in patients with congestive heart failure. However, little is known about whether this vascular response is an early change or a late manifestation of left ventricular dysfunction. Methods and Results. This investigation used a paced canine model of congestive heart failure to demonstrate that abnormal aortic input impedance does evolve in the setting of ventricular systolic dysfunction and to prospectively define the time course of change in aortic input impedance and conduit vessel compliance. Studies were performed in closed-chest conditioned beagles aged 1 to 2 years that underwent hemodynamic evaluation at baseline and after induction of left ventricular dysfunction by rapid ventricular pacing. Within 48 hours of the onset of rapid ventricular pacing, we observed mild left ventricular systolic dysfunction with an echocardiographically derived left ventricular ejection fraction of 37% (P