Estimation of cardiac output from left ventricular pressure by a modified modelflow method

The Modelflow method (MM) requires the recording of the aortic pressure signal, to compute cardiac output (CO) by simulating a non-linear three-element model of aortic input impedance. We propose an extended MM to be applied to the intraventricular pressure signal, to obtain an independent estimation of CO in the setting of conductance measurements. Hemodynamic tests were performed in 21 patients with heart failure during atriobiventricular pacing. Comparing CO by extended MM simulation with standard MM, the bias was -0.04 (0.36) l/min, with limits of agreement of -0.77 and 0.70 l/min, and a coefficient of variation of 8.4%. In patients without mitral and aortic abnormalities, the continuous CO estimation with the proposed method seems reliable. This method presents an acceptable precision to replace conventional aortic MM estimation in subjects undergoing intraventricular pressure acquisition, such as during conductance catheter evaluation.