Is contrast echocardiography safe and useful for the assessment of left ventricular function in the perioperative period after cardiac surgery? A pilot study.

BACKGROUND: Myocardial contrast echocardiography (CE) improves the quality of standard echocardiography. The value of CE during the early post-operative period after coronary artery bypass grafting (CABG) has not yet been well established.

AIM: To evaluate the accuracy and safety of CE used for the assessment of left ventricular (LV) function in patients after CABG in the setting of a cardiosurgery post-operative unit (CPU) in comparison with conventional transthoracic echocardiography (TTE).

METHODS: Echocardiographic contrast agent Sono-Vue (Bracco, Italy) was administered in 30 consecutive patients with technically difficult TTE, after CABG treated in the CPU. Improved quality of echocardiographic imaging was assessed by the number of analysable LV segments. The LV end-diastolic and end-systolic volume (LVEDV, LVESV) and LV ejection fraction (LVEF) were calculated before and after contrast administration.

RESULTS: There were no side effects after contrast administration. The mean number of LV segments visualised after CE increased from 8.0 ± 4 to 16.9 ± 0.1 in all patients (52.4% of improvement); 272 (52.3%) out of 510 segments were described as poorly visible using standard TTE while only four (0.8%) segments were not visible after contrast administration. Out of all visible hypokinetic, akinetic and dyskinetic segments, 63 (12%) segments were classified wrongly. The LV volumes were smaller and LVEF significantly higher after CE compared to standard TTE (LVEDV 127 mL vs 98 mL; LVESV 65 mL vs 45 mL; p = 0.0002 and p = 0.0016, respectively). In all methods used: visual, Simpson's method and biplane method, LVEF was significantly higher compared to standard TTE (p = 0.012, p = 0.0088, p = 0.00065, respectively). In patients after surgical LV restoration, CE enabled the assessment of LV geometry, patch localisation and the exclusion of the presence of LV thrombus.

CONCLUSIONS: Contrast echocardiography is a rapid, simple and safe technique when performed at bedside in a cardiosurgery post-operative unit setting, permitting accurate both segmental and global wall motion analysis. The use of contrast echocardiography could help to identify causes leading to LV systolic dysfunction immediately after CABG surgery.