Patients undergoing aortic valve replacement are randomized to receive TENS (transcutaneous electrical nerve stimulation) or sham stimulation at one arm for 30 min under various anesthetic conditions: no anesthesia (preanesthesia), sevoflurane or propofol anesthesia. Cardioprotective effects of TENS are compared through Langendorff rat heart perfusion system using plasma dialysate from patients.

Patients undergoing aortic valve replacement are randomized to one of six groups: preanesthesia-TENS (transcutaneous electrical nerve stimulation), preanesthesia-sham, sevoflurane-TENS, sevoflurane-sham, propofol-TENS, propofol-sham. Patients receive TENS or sham stimulation (without electrical pulse generation) at one arm for 30 min under no anesthesia (preanesthesia) or sevoflurane or propofol anesthesia.

In all patients, blood samples are obtained before and after TENS or sham procedure to make plasma dialysate to perfuse rat hearts subjected to ischemia-reperfusion injury through Langendorff system.

Cardioprotective effects are determined by comparing infarct sizes of rat hearts perfused with human plasma dialysate, which reflects cardioprotective effects of TENS in human subjects. By comparing infarct size differences, the myocardial protective effects of TENS in various anesthetic conditions can be determined in human subjects undergoing aortic valve replacement.

Inclusion Criteria:

• patients undergoing aortic valve replacement

Exclusion Criteria:

• co-medications: metformin, nitroglycerine, nicorandil
• discomfort at TENS or loss of intact skin
• uncontrolled hypertension or diabetes mellitus
• severely impaired renal or hepatic function
• peripheral vasculopathy or neuropathy
• did not consent to participate
• pregnancy