Preload recruitable stroke work relationship in the right ventricle: simultaneous assessment using conductance catheter and sonomicrometry

OBJECTIVE: To examine the suitability of the conductance catheter technique for assessment of right ventricular systolic myocardial performance by using preload recruitable stroke work, we compared variables obtained simultaneously by conductance catheter and sonomicrometry dimension techniques. In addition, linearity of volume relationships was studied during rapid preload alteration by bicaval occlusion. DESIGN: Prospective animal study. SETTING: University research laboratory. SUBJECTS: Anesthetized and ventilated swine (n = 9). INTERVENTIONS: Right intraventricular volumes were determined simultaneously by conductance catheter and sonomicrometry by using an ellipsoid shell subtraction model in open-chest swine. Animals were studied at the baseline state and under alterations of afterload, preload, and inotropy. Under each condition, steady-state recordings and transient bicaval occlusions were performed. Agreement of preload recruitable stroke work slope was assessed by using the Bland-Altman analysis, and second-order polynomials were fit to examine volume relationships during bicaval occlusions. MEASUREMENTS AND MAIN RESULTS: At steady state, the relationships for stroke-volumes and end-diastolic volumes were linear between the two methods. Altered physiologic conditions induced by the various interventions produced quantitatively similar changes in preload recruitable stroke work slope within an animal, although absolute values differed in some animals. Regression analysis of the preload recruitable stroke work slope revealed a significant intervention effect independent of the method used. During some bicaval occlusions, nonlinear relationships were observed similarly with both methods. CONCLUSIONS: These results suggest that changes in right ventricular systolic contractility assessed by the preload recruitable stroke work relationship were similar when measured by conductance catheter and sonomicrometry, although absolute values may differ in some animals.