Acute Study to Collect Electrical Signals From the Heart Using a Special Lead

Inclusion Criteria: * Subject must be undergoing surgical procedure for approved indications for: * cardiothoracic surgery where a midline sternotomy is planned, or * cardiothoracic surgery where a subxiphoid/paraxiphoid cut for a chest tube is planned, or * VT ablation procedure with epicardial access, or * implant of a subcutaneous ICD (S-ICD®), or implant of a transvenous ICD (single or dual chamber) * Subject must be willing to provide Informed Consent * Subject must be ≥ 18 years old Exclusion Criteria: * Subject has known hiatus hernia or moderate or worse pectus excavatum * Subject had previous pericarditis or prior sternotomy * Subject has known significant Right Ventricle/ Right Ventricular dilation * Subject has hypertrophic cardiomyopathy * Subject is pacemaker dependent * Subject has known skin irritations due to the Covidien Multi-function defibrillation electrode * Subject is considered to be at high risk for infection(1) * Subject has Left Ventricular Ejection Fraction \< 20% (most recent available LVEF measurement in the last 6 months) * Subject has New York Heart Association Class IV * Subject has myocardial infarction within the last 6 weeks * Subject currently has unstable angina * Subject has severe aortic stenosis * Subject at high risk of stroke (2) * Subject has Chronic Obstructive Pulmonary Disease and is oxygen dependent * Subject has permanent AF and will not be adequately anticoagulated during the ASD2 Acute Testing procedure (3) * Subject with an implanted active cardiac or non-cardiac device during the ASD2 Acute Testing procedure (e.g., ICD, S-ICD®, Pacemaker, Neuro stimulator) * Subject is enrolled in a concurrent study that may confound the results of this study, without documented pre-approval from a Medtronic study manager * Subject has any medical condition that would limit study participation * Subject is pregnant, or of childbearing potential and not on a reliable form of birth control. Women of childbearing potential are required to have a negative pregnancy test within 7 days prior to the ASD2 Acute Testing procedure * Subject meets exclusion criteria required by local law (e.g. age, breast feeding,etc.) * Subject is legally incompetent 1. Screening subjects at high risk for infection will be based on the local investigator judgment decision. 2. Subjects who are at high risk for stroke should be screened according to local country guidelines or, in case of their absence, according to ACC/AHA/ESC 2006 Guidelines for High Risk Factors for Stroke (i.e. exclusion of subjects with previous stroke, TIA, or embolism; Mitral stenosis; prosthetic heart valve). 3. Screening will be based on the local investigator judgment decision.