Importance of pulmonary artery perfusion in cardiac surgery

Effects of pulmonary perfusion during cardiopulmonary bypass on lung functions after cardiac operation

BACKGROUND

Pulmonary artery perfusion during cardiopulmonary bypass (CPB) is a known but rarely used technique in adult cardiac surgery. In this study, we aimed to investigate biochemical and histopathological effects of pulmonary artery perfusion during CPB on lung functions.

METHODS

Between May 2014 and August 2014, all patients (n = 24) who gave informed consent for participating this study with inclusion criteria were included. Patients undergoing isolated coronary artery bypass grafting were sequentially randomized to conventional CPB (control group, n = 12) and conventional CPB with selective pulmonary artery perfusion (study group, n = 12). Lung functions were monitored using PF ratio, alveolar-arterial oxygen gradient, and lactate levels. A small sample tissue from the left lung was excised for histopathologic examination. Immunocytochemistry analysis was performed using anti-rabbit polyclonal vascular endothelial growth factor (VEGF), rabbit polyclonal inducible nitric oxide synthase (i-NOS), and BCL-2 antibodies.

RESULTS

Postoperative course of the patients were uneventful without any clinical outcome differences in terms of cardiopulmonary complications, ventilation time and hospital stay. Pulmonary perfusion group had significantly better oxygenation values after extubation and at postoperative 24-hour. Electron microscopy examinations revealed better preservation of the alveolar wall integrity with pulmonary perfusion. The intensity of VEGF, i-NOS, and BCL-2 antibody expressions in bronchial epithelial cells were more prominent in the pulmonary perfusion group.

CONCLUSIONS

Pulmonary artery perfusion during aortic cross-clamping provides better oxygenation and preservation of the wall alveolar integrity after coronary artery bypass grafting surgery. This technique can be used as a protective strategy to minimize CPB-induced lung injury in adult cardiac surgery.

Does Pulmonary Artery Venting Decrease the Incidence of Postoperative Atrial Fibrillation after Conventional Aortocoronary Bypass Surgery?

<strong>Objectives</strong>: In this study, we tested the hypothesis that<br />pulmonary artery venting would decrease the incidence of<br />atrial fibrillation after coronary artery bypass surgery.<br /><strong>Methods</strong>: This prospective study included 301 patients<br />who underwent complete myocardial revascularization with<br />cardiopulmonary bypass in our department during a 2-year<br />period. The patients were randomly divided into 2 groups:<br />group I included 151 patients who underwent aortic root<br />venting and group II included 150 patients who underwent<br />pulmonary arterial venting for decompression of the left<br />heart. Pre-, peri-, and postoperative risk factors for atrial<br />fibrillation were assessed in both groups.<br /><strong>Results</strong>: The mean age was similar in the 2 groups. The<br />mean number of anastomoses was significantly higher in<br />group I (2.8 ± 0.8) than in group II (2.4 ± 0.8) (P = 0.001).<br />The mean cross-clamp time was 42.7 ± 17.4 minutes in group<br />I and 54.1 ± 23.8 minutes in group II (P = 0.001). The mean<br />cardiopulmonary bypass time was 66.4 ± 46.1 minutes in<br />group I and 77.4 ± 28.6 minutes in group II (P = 0.08). The<br />incidence of atrial fibrillation was 14.5% (n = 21) in group I<br />and 6.5% (n = 10) in group II (P = 0.02). Multivariate regression<br />analysis showed that pulmonary artery venting decreased<br />the postoperative incidence of atrial fibrillation by 17.6%.<br /><strong>Conclusions</strong>: Pulmonary arterial venting may be used as<br />an alternative to aortic root venting during on-pump coronary<br />bypass surgery, especially in patients at high risk of postoperative<br />atrial fibrillation.

Does on-pump normothermic beating-heart valve surgery with low tidal volume ventilation protect the lungs?

BACKGROUND

Postoperative pulmonary dysfunction following cardiopulmonary bypass (CPB) usually develops secondary to the inflammatory process with contact activation, hypothermia, operative trauma, general anesthesia, atelectasis, pain, and pulmonary ischemia/reperfusion due to cross-clamping. The aim of the present study was to evaluate the effects of an on-pump, normothermic, and beating-heart technique and of low-volume ventilation on lung injury.

METHODS

We compared the results for 20 patients who underwent operations with an on-pump, normothermic, and beating-heart technique of mitral valve surgery with low-volume ventilation (group 1) with the results for 23 patients who underwent their operations with an on-pump, hypothermic cardiac-arrest technique (group 2). In both groups, blood samples were collected from the right superior pulmonary vein, and inflammation and oxidative stress markers (malondialdehyde, lactic acid, platelet-activating factor, and myeloperoxidase) were studied.

RESULTS

Malondialdehyde, myeloperoxidase, and lactate values were significantly lower in group 1 than in group 2 just before the termination of CPB (P < .05). We observed no differences between the 2 groups with regard to values for platelet-activating factor.

CONCLUSIONS

Inflammation and oxidative stress markers were lower in the group of patients who underwent beating-heart valve surgery with low-volume ventilation. These results reflect less of an ischemic insult and lower inflammation compared with the results for the patients who underwent conventional operations.

Pulmonary protection during cardiac surgery: systematic literature review

Ischemia-reperfusion injury occurs during heart surgery in which cardiopulmonary bypass is used. Current knowledge of the factors contributing to postoperative pulmonary dysfunction and the measures to avoid it are reviewed.