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Monitoring the variation in myocardial function with the Doppler-derived myocardial performance index during aortic cross-clamping.

OBJECTIVES
To investigate the effects of acute elevation in afterload on global (systolic and diastolic) myocardial function by performing serial intraoperative transesophageal echocardiograms during and after cross-clamp application on patients undergoing elective abdominal aortic aneurysm (AAA) surgery.


DESIGN
A prospective observational study.


SETTING
A tertiary care university hospital.


PARTICIPANTS
Patients undergoing elective AAA repair under general anesthesia (GA).


INTERVENTION
The use of perioperative transesophageal echocardiography to calculate a tissue Doppler-derived myocardial performance index (MPI) during different stages of the surgery.


MEASUREMENT AND RESULTS
Twenty consecutive patients scheduled for suprarenal AAA repair under GA were included in the study. Perioperative transesophageal echocardiography was performed after the induction of GA. MPI was calculated with Doppler tissue imaging as the sum of isovolumetric contraction and relaxation times divided by the ejection time before cross-clamping of the aorta and then 2, 10, and 20 minutes after cross-clamp application. A final MPI was measured after unclamping of the aorta. As compared with baseline, cross-clamp application initially worsened MPI within 2 minutes and then MPI improved to baseline after 10 minutes of cross-clamp application. The MPI improved significantly after unclamping of the aorta.


CONCLUSIONS
The authors observed a temporal variation in global myocardial function after the application of a cross-clamp in the suprarenal position. There was transient deterioration of global myocardial function (the prolongation of MPI) 2 minutes after cross-clamp application, which improved within 10 minutes. Myocardial function returned to baseline after unclamping the aorta.