Models incorporating stroke volume and end-systolic pressure of the preceding beat as well as ejecting beat end-systolic and end-diastolic pressure were consistently superior to all other models.
Stroke volume regulation on a beat-to-beat basis is best modeled by incorporating the end-systolic pressure and stroke volume of the preceding beat alongside current beat parameters.
To better define beat-to-beat regulation of stroke volume (SV), the several-beat transient response of the left ventricle (LV) to sudden changes in hydraulic loading impedance was studied. Data were collected from eight canine isolated heart-lung preparations with controlled LV loading impedance. At a selected diastolic interval, a sudden increase in hydraulic loading resistance was induced. The resulting transient response in SV, end-diastolic pressure (EDP), and end-systolic pressure (ESP) was analyzed by comparing the relative predictive capability of six competing models, each incorporating different degrees of complexity in the relationship between SV and EDP and ESP. The basic model assumed linear LV pressure-volume relationships at both end diastole and end systole. Incorporation of nonlinear, end-state interaction or coronary perfusion pressure effects into the basic model did not improve predictive performance. Models incorporating SV and ESP of the preceding beat as well as ejecting beat ESP and EDP were consistently superior to all other models. The ranking of the relative influence of the determinants of SV was 1) ejecting beat ESP, 2) preceding beat ESP, 3) ejecting beat EDP, and 4) preceding beat SV.
Slinker et al. (Thu,) reported a other. Sudden increase in hydraulic loading resistance was evaluated on Predictive capability of models for transient response in stroke volume, end-diastolic pressure, and end-systolic pressure. Models incorporating stroke volume and end-systolic pressure of the preceding beat as well as ejecting beat end-systolic and end-diastolic pressure were consistently superior to all other models.