Measurement of left ventricular contractility using transesophageal echocardiography in patients undergoing coronary artery bypass grafting

Abstract

Optimal assessment of left ventricular function requires the use of load-independent indices of myocardial contractility, which often are difficult to obtain in patients undergoing coronary artery bypass graft (CABG) surgery. We have investigated whether the relation between left ventricular end-systolic stress (ESS) (derived from high-fidelity intraventricular pressure measurements and transesophageal-derived wall thickness) and end-systolic area (ESA) (derived from transesophageal echocardiography [TEE]) could provide a load-independent index of left ventricular function. We studied seven men undergoing coronary revascularization. Multiple data points at varied loading conditions were generated for each patient by infusions of sodium nitroprusside and phenylephrine during the period immediately after induction of general anesthesia and preceding surgical incision. While peak systolic blood pressure was pharmacologically altered between 78 and 204 mm Hg, the correlations between ESS and ESA were excellent for all patients (range r = 0.90 to 0.99). Additionally, the slopes of these relations showed a close correlation to their respective baseline thermodilution cardiac indices ( r = 0.85, p = 0.02). Appropriate shifts of the ESS ESA relationships were documented during postextrasystolic potentiation. The authors conclude that the left ventricular ESS ESA correlation, derived using TEE and intraventricular pressure measurements, may provide a load-independent index of left ventricular inotropic state in patients undergoing CABG surgery.