The current study will evaluate the potential of stimulating the R.auricularis of the vagus nerve located at the Fossa triangularis to ameliorate or suppress AF in the study Population!

Scientific Background Nearly 30% of patients undergoing coronary artery bypass grafting (CABG), 40% of patients undergoing valvular heart surgery and over 50% of patients with combined coronary and valvular procedures develop atrial fibrillation (AF).

Postoperative AF occurs mostly due to conditions like chronic kidney diseases, emergency surgery, age >75 years, cardiopulmonary bypass time >180 min and due to lacking postoperative application of aldosterone- and beta-blockers.

An overview of pre- intra- and postoperative risks for AF is listed in

Table 1: Pre-, intra-, postoperative risks for AF.

Preoperative High age Male gender Previous cardiac surgery Valvular heart disease Chronic lung disease Chronic renal failure Leſt atrium enlargement Leſt ventricular hypertrophy Withdrawal of beta-blocker medication History of AF Hypertension Obesity Diabetes Metabolic Syndrome

Intraoperative Endotracheal tube insertion Intraoperative IABP Leſt ventricular venting Aortic cross-clamp time Extracorporeal circulation Myocardial ischemia Venous cannulation Damage to the atrium Excess inotropic requirements Acute volume change

Postoperative Return to intensive care unit Ventilation longer than 24 hours Volume overload Pneumonia Electrolyte imbalances Imbalance of auton. nervous system Atrial extrasystole Increased postop adrenergic status Increased aſterload Inflammation Hypotension

Several theories describe the emergence of AF like "multiple-wavelet re-entry", "focal mechanism" and "mother rotor" but the exact underlying mechanisms are still not well understood.

Prevention and treatment of postoperative AF are managed with conservative medication therapies including e.g. beta-blockers and other clinical interventions include radio frequency catheter ablation, cardioversion and occlusion of the left atrial appendage.

A novel approach for suppression of AF utilizing low-level transcutaneous electrical vagus nerve stimulation has been described recently in the Journal of the American College of Cardiology. The newly developed "DUCEST Neurostimulator V" device (manufactured by Biegler Medizinelektronik GmbH Mauerbach, Austria) offers similar action as in. This Neurostimulator device is designed to emit small direct current electrical pulses (0-1,2mA) to stimulate the R.auricularis of the vagus nerve located at the Fossa triangularis. The target population are patients with de-novo postoperative AF. The stimulation is achieved with the attachment of two needle- electrodes and connection of the electrodes to the Neurostimulator.

Following the stimulation of the vagus nerve positive effects were already achieved in chronical wound healing, peripheral artery occlusive disease (PAOD), Claudicatio intermittens (CI) and chronic pain patients.

Inclusion Criteria:

• De-novo postoperative AF
• CABG or aortic valve replacement
• Age of 18-80 years
• Willing and able to understand, sign and date the informed consent form that has been approved by the institutional review board

Exclusion Criteria:

• Pacemaker or ICD
• Impaired EF < 30%
• Patients with acute myocardial infarction within the past 14 days
• Pregnant or lactating patients
• Any condition that, in the judgement of the investigator, would place the patient at undue risk
• Any concurrent disease or condition that, in the opinion of the investigator, would make the subject unsuitable for participation in the study
• Treatment and/or an uncompleted follow-up treatment of any investigational therapy within 6 months before procedure and intent to participate in any other investigational drug or cell therapy study during the follow-up period of this study
• Active participation in other Research therapy for cardiovascular repair/regeneration