Low-dose dobutamine stress and left ventricular wall motion monitored with transesophageal echocardiography versus hemodynamic data derived from pulmonary artery catheterization in patients scheduled for CABG.

BACKGROUND

The clinical acceptance of transesophageal echocardiography (TEE) as a monitoring technique for left ventricular function in open-heart surgery is now widely recognized. This technique's accurate imaging capabilities have been found to improve the information obtained by the pulmonary catheter (PAC) and thermodilution. TEE is also a less invasive technique than PAC. However, because it is costly, further comparisons between the techniques are worthwhile. This study compares hemodynamic data obtained with PAC and how these correspond to echocardiography data using TEE.

METHODS

Twenty-four anesthetized patients undergoing elective coronary artery bypass grafting (CABG) were studied. They were monitored with PAC and TEE. A low-dose dobutamine protocol for viability was used with doses of 5 and 10 microg x kg(-1) x min(-1). Endpoints for this stimulation included on-line visual change in left ventricle wall motion (LVWM), increased arterial blood pressure more than 40 mmHg, a heart rate (HR) increase of more than 20%, or ST depression on ECG exceeding 0.2 mV. Visual assessment of LVWM using the transgastric short-axis view was made off line by a blinded observer. Six segments were used and a wall motion score was made at each level of dobutamine stimulation.

RESULTS & CONCLUSION: Two patients reached the endpoint for elevated blood pressure with a dobutamine dose of 5 microg x kg(-1) x min(-1), and twenty-two patients were stimulated to 10 microg x kg(-1) x min(-1). There were significant increases in cardiac output (CO), stroke volume (SV), systolic arterial pressure (SAP), mean arterial pressure (MAP), diastolic arterial pressure (DAP), pulmonary capillary wedge pressure (PCWP) and left ventricle stroke work index (LVSWI), but not in HR and systemic vascular resistance (SVR). Moreover, the LVWM increased significantly, but not fractional area change (FAC). The main finding, however, was the increase in SV with an accompanying improvement in LVWM, suggesting that visual assessment of improved wall motion could substitute PAC and thermodilution monitoring in clinical settings which demand a quick estimate of left ventricular performance.