High Septal Pacing for Cardiac Resynchronization Therapy

Inclusion Criteria: * 50 years of age or older * Patients willing and capable of providing informed consent, participating in all testing associated with this clinical investigation * Patients undergoing a CRT implant procedure (pacemaker or defibrillator) for one of the following reasons * Indicated for a new device * Device upgrade * Device replacement * Lead revision * Note: recognized indications for CRT-P and CRT-D as of October 2009 are valid for inclusion in this study. Should new indications become approved during the study conduct; those will also be applied within the inclusion criteria. Exclusion Criteria: * Patients unwilling or incapable of signing the informed consent, or patients having previously withdrawn their consent * Patients in AF that cannot be cardioverted for the study * RBBB pattern * Sustained, uncontrolled ventricular tachycardia * Sinus rhythm \< 30 bpm or \>100 bpm * Complete AV node block * Second degree AV block * Women who are pregnant or plan to become pregnant during the study (method of assessment upon physician's discretion); * History of (hemorrhagic) cerebro-vascular accident or TIA