Invited commentary

Abstract

Hemodynamic instability occurs frequently during off-pump coronary artery bypass (OPCAB) as a result of manipulation of the beating heart. This is particularly the case when the heart has to be lifted and rotated during coronary surgery in order to expose the coronary vessels of the lateral and inferior wall. Under these circumstances, diastolic filling of the right ventricle is compromised, leading to a reduced blood flow to the pulmonary artery. This reduces the filling of the leftventricle, which decreases stroke volume and cardiac output. A right ventricular assist device (RVAD) used during OPCAB pumps blood to the pulmonary circulation to maintain cardiac output and stabilize systemic hemodynamics.Based on this rationale, Caputo and colleagues evaluated such a RVAD, the A-Med system, in a randomized study in OPCAB patients. A major finding of this study is a significant reduction of central venous pressure in the RVAD-supported patients during exposure of coronary vessels located on the lateral and posterior ventricular wall. This beneficial effect may have contributed to maximal left ventricular filling and maintenance of hemodynamic stability, which, regrettably, is not detailed in this report. The findings of a reduced inflammatory response in OPCAB patients compared with on-pump patients are in line with previous publications.It seems clear that patients who are operated off-pump (ie, by eliminating the adverse effects of cardiopulmonary bypass on blood elements and humoral components) develop a far lesser postoperative inflammatory response than patients that are operated on-pump. However, surgical trauma and other operative events still cause a mild to moderate inflammatory response in OPCAB patients, as seen in this report by a transient postoperative elevation of Interleukine-6, Interleukin-8, complement C3a, and markers of organ injury Troponin I and S100. According to this study, there seems to be no difference between the OPCAB and RVAD patients regarding their postoperative inflammatory response and organ function, which suggests that the use of this RVAD does not promote inflammation indicated by comparable inflammation as in OPCAB patients without RVAD.As OPCAB operations are now more widely applied in coronary surgery, it is important to investigate which category of patients, especially those with high-risk profiles who benefit most from RVAD support. Hemodynamic instability occurs frequently during off-pump coronary artery bypass (OPCAB) as a result of manipulation of the beating heart. This is particularly the case when the heart has to be lifted and rotated during coronary surgery in order to expose the coronary vessels of the lateral and inferior wall. Under these circumstances, diastolic filling of the right ventricle is compromised, leading to a reduced blood flow to the pulmonary artery. This reduces the filling of the leftventricle, which decreases stroke volume and cardiac output. A right ventricular assist device (RVAD) used during OPCAB pumps blood to the pulmonary circulation to maintain cardiac output and stabilize systemic hemodynamics. Based on this rationale, Caputo and colleagues evaluated such a RVAD, the A-Med system, in a randomized study in OPCAB patients. A major finding of this study is a significant reduction of central venous pressure in the RVAD-supported patients during exposure of coronary vessels located on the lateral and posterior ventricular wall. This beneficial effect may have contributed to maximal left ventricular filling and maintenance of hemodynamic stability, which, regrettably, is not detailed in this report. The findings of a reduced inflammatory response in OPCAB patients compared with on-pump patients are in line with previous publications. It seems clear that patients who are operated off-pump (ie, by eliminating the adverse effects of cardiopulmonary bypass on blood elements and humoral components) develop a far lesser postoperative inflammatory response than patients that are operated on-pump. However, surgical trauma and other operative events still cause a mild to moderate inflammatory response in OPCAB patients, as seen in this report by a transient postoperative elevation of Interleukine-6, Interleukin-8, complement C3a, and markers of organ injury Troponin I and S100. According to this study, there seems to be no difference between the OPCAB and RVAD patients regarding their postoperative inflammatory response and organ function, which suggests that the use of this RVAD does not promote inflammation indicated by comparable inflammation as in OPCAB patients without RVAD. As OPCAB operations are now more widely applied in coronary surgery, it is important to investigate which category of patients, especially those with high-risk profiles who benefit most from RVAD support.