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Free Oral Sessions: Echocardiography

Right ventricular function after on-pump versus off-pump coronary artery bypass graft surgery, a TDI study

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Michaux, I.; Filipovic, M.; Skarvan, K.; Bolliger, D.; Seeberger, M. D.

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European Journal of Anaesthesiology (EJA): May 2006 - Volume 23 - Issue - p 5
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Introduction: Impairment of right ventricular (RV) function has been observed after on-pump coronary bypass graft (CABG) surgery [1]. The use of cardiopulmonary bypass and perioperative myocardial ischaemia have been discussed as possible reasons for this problem. We hypothesized that avoiding cardiopulmonary bypass by performing off-pump coronary artery bypass (OPCAB) surgery would better preserve RV function.

Method: With approval from the institutional ethics committee and informed written consent, we equally randomized 50 elective coronary surgical patients to CABG or OPCAB surgery. Transthoracic echocardiography was performed the day before and 3 months after surgery. The parasternal short-axis view was used to record the ejection signal of the right ventricle (pulsed wave (PW) Doppler) and the apical 4-chamber view to record the tricuspid inflow velocities (PW Doppler), and the peak systolic velocity (Sa) and peak diastolic velocity (Ea) of the lateral tricuspid annulus (PW tissue Doppler imaging, TDI). The time interval from cessation to onset of two consecutive tricuspid inflow signals (Time A) and the time interval from onset to cessation of the RV ejection signal (Time B) were used to calculate the RV myocardial performance index (RV-MPI) as (Time A - Time B)/Time B. Analysis of the continuous variables was performed by non-parametric tests (Mann-Whitney U test or Wilcoxon's signed rank test) on an intention to treat basis. Data are mean ± S.D. [median].

Results: Surgery was completed according to randomization in 48/50 patients. Conversion to cardiopulmonary bypass was performed in two of the 25 patients randomized to the OPCAB group because of haemodynamic instability. Four patients were lost from follow-up, 3 in the CABG and 1 in the OPCAB group. The echocardiographic data are shown in the Table.

Table
Table:
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Discussion: Three months after surgery, systolic RV function was similarly impaired in both groups. Diastolic RV function, as indicated by Ea, was impaired in the CABG group only but inter-group differences did not reach statistical significance. Overall RV function, as indicated by the MPI, was preserved in both groups. We conclude that the choice of surgical intervention had only minimal influence on RV function 3 months after surgery.

Reference:

1 Alam M, Hedman A, Nordlander R, et al. Right ventricular function before and after an uncomplicated coronary artery bypass graft as assessed by pulsed wave Doppler tissue imaging of the tricuspid annulus. Am Heart J 2003; 146: 520-526.
© 2006 European Society of Anaesthesiology