Influence of temperature management on neurocognitive function in biological aortic valve replacement. A prospective randomized trial.
OBJECTIVE
Aim of this study was to elucidate if postoperative neurocognitive function after biological aortic valve replacement (AVR) can be influenced by temperature management during cardiopulmonary bypass (CPB).


METHODS
In this prospective randomized study, we measured the effect of mild hypothermic (32 °C, N.=30) vs. normothermic (37 °C, N.=30) CPB on neurocognitive function. All patients underwent elective isolated biological AVR (mean age 67 ± 8 years, mean additional EuroSCORE 5.6 ± 2.4). Neurocognitive function was objectively measured by means of objective P300 auditory-evoked potentials before surgery, one week and four months after surgery. Clinical data and outcome were monitored.


RESULTS
P300 evoked potentials were comparable between patients operated with mild hypothermic (370 ± 30 ms) and normothermic CPB (373 ± 32 ms) before surgery (P=0.85). P300 peak latencies were prolonged (=impaired) in patients operated with normothermic (402 ± 29, P<0.0001) as well as with mild hypothermic CPB (405 ± 30 ms, P<0.0001) one week after surgery. Even four months after surgery, still impairment of P300 peak latencies could be documented in either patients operated with normothermic (394 ± 28 ms) and mild hypothermic CPB (400 ± 33 ms,) in repeated measures analysis of variance (P=0.042). Group comparison revealed no difference between patients operated with normothermic and mild hypothermic CPB at one week (P=0.54) and four months (P=0.67) after surgery. Clinical data as well as postoperative adverse events were comparable between the two groups.


CONCLUSIONS
Normothermic temperature management during CPB is non-inferior to hypothermic in means of neuroprotection. Since patients after biological aortic valve replacement show a subclinical but measurable cognitive deficit up to four months after surgery, other factors have to be addressed to add further benefit to the extremely good results of open biological AVR.
Division of General Thoracic Surgery, University Hospital Bern, University of Bern, Bern, Switzerland.
R
R
Fakin
D
D
Zimpfer
G H
GH
Sodeck
A
A
Rajek
B
B
Mora
J
J
Dumfarth
M
M
Grimm
M
M
Czerny
D000368:Aged; D001021:Aortic Valve / Q000601:surgery*; D001705:Bioprosthesis; D001831:Body Temperature / Q000502:physiology*; D002315:Cardiopulmonary Bypass / Q000379:methods; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000517:prevention & control; D017558:Elective Surgical Procedures; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D005260:Female; D005500:Follow-Up Studies; D006349:Heart Valve Diseases / Q000601:surgery*; D006350:Heart Valve Prosthesis; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D008297:Male; D011184:Postoperative Period; D011446:Prospective Studies; D011594:Psychometrics; D016896:Treatment Outcome