Key result
Deep hypothermia during cardiopulmonary bypass significantly downregulated 19 myocardial proteins associated with energy production, which returned to pre-cooling levels upon rewarming, while 10 other proteins regulating cardiac contraction and adaptor proteins remained downregulated.
Why the study?
Does deep hypothermic cardiopulmonary bypass and subsequent rewarming alter the human myocardial proteome compared to normothermic bypass in patients undergoing thoracic aortic repair?
Cohort (n=16)
No
Does deep hypothermic cardiopulmonary bypass and subsequent rewarming alter the human myocardial proteome compared to normothermic bypass in patients undergoing thoracic aortic repair?
Rewarming after deep hypothermic cardiopulmonary bypass largely restores the myocardial proteome to its pre-cooled state, though specific proteins regulating cardiac contraction remain downregulated.
These proteomic shifts should not yet alter bypass temperature selection; leaves open their impact on postoperative myocardial recovery.
BACKGROUND: Hypothermia is utilized in cardiac and aortic surgery to protect organs from ischemic reperfusion injury. Although the cooled body is invariably rewarmed after the procedure, it is still unknown whether the rewarmed body regains its former biological state. This study determined the modulatory effects of hypothermia on the human myocardial proteome and whether subsequent rewarming restores the proteome to the state prior to cooling. METHODS AND RESULTS: A quantitative proteomic analysis was performed using isobaric tags for relative and absolute quantification labeling tandem mass spectrometry. Right atrial samples were taken 3 times (pre, during and post cooling) during deep hypothermic cardiopulmonary bypass (CPB) from 8 patients with aortic arch aneurysms and 3 corresponding time points during normothermic CPB from 8 patients with ascending aortic or valsalva aneurysms. In total, 697 proteins were identified, with 222 proteins having high protein confidence. Bioinformatic analyses revealed significant downregulation of 19 proteins associated with energy production at hypothermic cardioplegic arrest. On rewarmed beating, 10 proteins remained downregulated, including those regulating cardiac contraction and adaptor proteins, although levels of the aforementioned 19 downregulated proteins returned to their initial values. Additional echocardiographic evaluation demonstrated that hypothermia preserved the variables of diastolic function to a greater extent than normothermic surgery. CONCLUSIONS: Rewarming restores the human myocardial proteome to the pre-cooled state, except for proteins regulating cardiac contraction and adaptor proteins.
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Oda et al. (2015) conducted a cohort in Thoracic aortic aneurysms (n=16). Deep hypothermic cardiopulmonary bypass and rewarming vs. Normothermic cardiopulmonary bypass was evaluated on Changes in the human myocardial proteome (restoration of downregulated proteins after rewarming). Deep hypothermia during cardiopulmonary bypass significantly downregulated 19 myocardial proteins associated with energy production, which returned to pre-cooling levels upon rewarming, while 10 other proteins regulating cardiac contraction and adaptor proteins remained downregulated.
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