The purpose of this study is to demonstrate the safety and effectiveness of the VDI UHF-ECG System in the diagnosis of ventricular dyssynchrony when compared to the 12-lead ECG in patients with bradycardia and heart failure indicated for pacemaker implantation.

Inclusion Criteria:

• Adults with bradycardia or heart failure scheduled for first time pacemaker implant (including CRT/CSP) with one of the following: Bradycardia with ventricular synchrony and QRS duration <= 110 ms, Bradycardia with LBBB, Bradycardia with RBBB, Bradycardia with other IVCD necessitating intervention, or Heart failure with LBBB
• Understands the nature of the study and is willing to comply with all study requirements.
• Provides written informed consent.
• A negative pregnancy test prior to the procedure for participants of child-bearing potential.

Exclusion Criteria:

• Complete AV block (3rd-degree AV block) without a stable escape rhythm or other circumstances where there is no measurable QRS.
• Subjects with a previous or current pacemaker or defibrillator implant.
• Anatomical or other conditions that may make a 12-lead ECG difficult to obtain, such as an allergy to components of the ECG pads, burns, open wounds, etc.
• Currently enrolled in another investigational device or drug trial that has not completed the active treatment phase and/or would conflict with this study.
• Other co-morbid condition(s) that could limit the participant's ability to participate in the study or to comply with study requirements or impact the scientific integrity of the study.

Different QRS duration requirements for male and female.

Participants who are eligible for this study must have bradycardia or heart failure and are scheduled for pacemaker device implantation. Baseline ECG requirements must be met.