The WiCS-LV system is an alternative means to providing left ventricular stimulation for Cardiac Resynchronization Therapy (CRT). The purpose of this study is to evaluate the safety and performance of the WiCS-LV System in patients with indications for CRT.

Eligible patients will undergo an acoustic window assessment using transthoracic echocardiography. Patients with adequate acoustic windows will undergo implantation of the WiCS-LV system.

Patients will undergo evaluations pre-hospital discharge, and at one month, 3 months, and 6 months post implantation. Extended follow-up will be obtained via a registry at 1, 2, 3, 4, and 5 years post implantation.

Inclusion Criteria:

Patients with standard indication for CRT based upon the most recent guidelines AND meeting criteria for one of these three categories:

1. Patients with previously implanted pacemakers or ICD's and meeting standard indications for CRT - referred to as "upgrades"
2. Patients in whom attempted coronary sinus lead implantation for CRT has failed - referred to as "untreated"
3. Patients with previously implanted CRT device, not responding to CRT (no change or worsening of symptom or NYHA functional class after 6 months of treatment confirmed by investigator) - referred to as "non-responders"

Exclusion Criteria:

1. Inability to comply with the study follow-up or other study requirements
2. Contraindication to heparin
3. Contraindication to both chronic anticoagulants and antiplatelet agents
4. Contraindication to iodinated contrast agents
5. Intracardiac thrombus by transesophageal echocardiography
6. Age less than 18 years
7. Attempted IPG implant within 3 days
8. Life expectancy of < 12 months
9. Chronic hemodialysis
10. Myocardial infarction within one month
11. Major cardiac surgery within one month
12. Female of childbearing potential, pregnant, or breastfeeding
13. Noncardiac implanted electrical stimulation therapy devices