Contrasting effect of different cardiothoracic operations on echocardiographic right ventricular long axis velocities, and implications for interpretation of post-operative values

BACKGROUND: Patients undergoing coronary artery bypass grafting (CABG) experience a reduction in right ventricular long axis velocities post surgery. OBJECTIVES: We tested whether the phenomenon of right ventricular (RV) long axis velocity decline depends on the chest being opened fully by mid-line sternotomy, pericardial incision, or on the type of operation performed. METHOD: By intraoperative transoesophageal echocardiography (TEE) we recorded serial right ventricular (RV) systolic pulse-wave tissue Doppler velocities during 6 types of elective procedure: 53 CABG surgery, 15 robotic-assisted minimally-invasive CABG (RCABG), 28 aortic valve replacement (AVR), 8 minimally-invasive aortic valve replacement (mini-AVR), 5 mediastinal mass excision, and 1 left atrial myxoma excision. Pre and post operative transthoracic echocardiography (TTE) were also conducted. RESULTS: Surgery without substantial opening of the pericardium did not significantly reduce RV systolic velocities (RCABG 13 ± 1.8 versus 12.4 ± 2.7 cm/s post; mini-AVR 11.9 ± 2.3 versus 11.1 ± 2.3 cm/s; mediastinal mass excision 13.9 ± 3.1 versus 13.8 ± 4 cm/s). In contrast, within 5 min of pericardial incision those whose surgery involved full opening of the pericardium had large reductions in RV velocities: 54 ± 11% decline with CABG (11.3 ± 1.9 to 5.1 ± 1.6 cm/s, p<0.0001), 54 ± 5% with AVR (12.6 ± 1.4 to 5.7 ± 0.6 cm/s, p<0.001) and 49% with left atrial myxoma excision (11.3 to 15.8 cm/s). This persisted immediately after pericardial opening to the end of surgery (61 ± 11%, p<0.0001; 58 ± 7%, p<0.0001; 59% respectively). CONCLUSIONS: It is full opening of the pericardium, and not cardiac surgery in general, which causes RV long axis decline following cardiac surgery. The impact is immediate (within 5 min) and persistent.