A comparison of left ventricular performance indices measured by transesophageal echocardiography with automated border detection

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 [Vcf(c)]) 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 Vcf(c) 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/dt(max) · 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%, Vcf(c) was 0.6 ± 0.2 circ · s-1, Ees was 25.8 ± 11.6 mmHg · cm-2, PRSF was 60.8 ± 26.6 mmHg, and dP/dt(max) · - EDA-1 was 245 ± 123.4 mmHg · s-1 · cm-2. At 1 minimum alveolar concentration of a volatile anesthetic agent, FAC, Vcf(c), and dP/dt(max) · EDA-1 remained unchanged. Significant decreases in Ees (19%) and PRSF (28%) were observed. Conclusions: The association between pressure-dimension indices and Vcf(c) 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, Vcf(c), or dP/dt(max) · EDA-1. After myocardial revascularization, Ees and PRSF appear more sensitive than FAC or Vcf(c) for measuring changes in contractility.