An Analysis of the Left Ventricle as a Pressure and Flow Generator in the Intact Systemic Circulation

The effects of increasing and decreasing peripheral resistance on the relationship between aortic pressure and left heart output were investigated in 41 experiments in the dog. The data were analyzed in terms of the slope of the aortic pressure-cardiac output graphs. The results indicate a finite variable internal resistance for the left ventricle. In general it acts as a low resistance generator (constant pressure source) for situations of low peripheral resistance and as a higher resistance generator for situations of high peripheral resistance, although its constant pressure attributes were much more consistent and pronounced than its constant flow characteristics.