Transesophageal Echocardiographic Measurement of Cardiac Index by the Prosthetic Mitral Valve Method Is Not Similar to the Continuous Thermodilution Method Via a Pulmonary Artery Catheter

ObjectiveTo compare the agreement of cardiac index measurements between transesophageal echocardiography across the prosthetic mitral valve and the continuous thermodilution method through a pulmonary artery catheter (PAC-TD) in patients undergoing double-valve replacement.DesignObservational prospective study.SettingUniversity hospital.ParticipantsTwenty-five patients undergoing double-valve replacement (12 men and 13 women, age 25-78 years, ASA III-IV, NYHA II-III, LVEF≥45%). Patients were grouped according to their prosthesis (mechanical prosthesis v bioprosthesis).InterventionsAll patients underwent cardiac index assessment during double-valve replacement.Measurements and Main ResultsCardiac index across the prosthetic mitral valve was measured simultaneously using transesophageal echocardiography (CIMV) and PAC-TD (CIPAC) at 15, 30, 45, and 60 minutes after weaning from cardiopulmonary bypass, and at 0, 15, and 30 minutes after incision closure. A correlation was present between CIMV and CIPAC in both groups (mechanical prosthesis: r = 0.47, p<0.01; bioprosthesis: r = 0.60, p<0.01). In the mechanical prosthesis group, the bias between techniques (CIPACv CIMV) was−0.5 L/min/m2 (95% CI:−1.97 to 0.97), and error was 55%. In the bioprosthesis group, the bias between both techniques was−1.3 L/min/m2 (95% CI:−3.1 to 0.5), and error was 56%.ConclusionsA relatively weak correlation and lack of agreement between values of CIPAC and CIMV were observed in patients undergoing double-valve replacement. Therefore, transesophageal echocardiography might not be interchangeable with PAC-TD for measuring cardiac output or cardiac index. A regression equation is needed to correct the probable value of CIPAC. CIMV might be useful as a quantitative or semi-quantitative cardiac output measurement.