A Comparison of Left Ventricular Performance Indices Measured by Transesophageal Echocardiography with Automated Border Detection

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Abstract
Background: Automated border detection (ABD) allows semiautomated measurement of left ventricular (LV) areas. They can be combined with left ventricular pressure signals to generate pressure-area loops and pressure-dimension indices of contractility. This study compared conventional indices of ventricular performance (fractional area change [FAC] and circumferential fiber shortening [Vcfc]) with pressure-dimension indices of contractility. A secondary aim was to compare the effects of volatile anesthetics on the indices. Methods: Using transesophageal echocardiography with automated border detection, FAC and Vcfc were obtained in 23 patients after cardiopulmonary bypass. Left ventricular pressures were obtained with a left ventricular catheter. Preload reduction by inferior vena caval occlusion was used to obtain end-systolic elastance (Ees), preload recruitable stroke force (PRSF), and dP/dtmax x EDA(-1) (EDA = end-diastolic area). In 11 patients, the measurements were repeated at 1 end-tidal minimum alveolar concentration of halothane or isoflurane. The results are expressed as mean +/- SD. Results: After cardiopulmonary bypass, FAC was 31.1+/-7.9%, Vcfc was 0.6+/-0.2 circ x s(-1), Ees was 25.8+/-11.6 mmHg x cm(-2), PRSF was 60.8+/-26.6 mmHg, and dP/dtmax x EDA(-1) was 245+/-123.4 mmHg x s(-1) x cm(-2). At 1 minimum alveolar concentration of a volatile anesthetic agent, FAC, Vcfc, and dP/dtmax x EDA(-1) remained unchanged. Significant decreases in Ees (19%) and PRSF (28%) were observed. Conclusions: The association between pressure-dimension indices and Vcfc or FAC was weak or nonexistent. A reduction in myocardial contractility induced by the administration of volatile anesthetic agents was detected by Ees and PRSF, but not by FAC, Vcfc, or dP/dtmax x EDA(-1). After myocardial revascularization, Ees and PRSF appear more sensitive than FAC or Vcfc for measuring changes in contractility.

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