Cardiac Resynchronization Therapy Defibrillator Based Impedance Monitoring Study

This is a multi-center feasibility study intended to collect information on changes in
intra-thoracic impedance measurements from CRT-D devices. In order to obtain an
intra-thoracic impedance measurement, the device delivers a subthreshold impulse that
measures the resistance between two electrodes.

At the programmed interval, measurements will be obtained between six different lead
configurations.

Inclusion Criteria:

Eligible patients will meet all of the following:

1. Have an approved indication per American College of Cardiology/American Heart
Association/Heart Rhythm Society guidelines for implantation of a Cardiac
Resynchronization Therapy Defibrillator (CRT-D) or have a previously implanted St.
Jude Medical (SJM) CRT-D system capable of enabling the diagnostic impedance
monitoring feature with implant occurring within the last 14 days

2. Have had at least one hospitalization, emergency department visit, or clinic visit
within the past 12 months for treatment of decompensated heart failure requiring
intravenous diuretics, intravenous inotropes, Natrecor (Nesiritide) therapy, or an
increase in an oral diuretic of ≥100% over a 24 hour period

3. Have the ability to maintain a patient diary for recording daily weights, symptoms
related to heart failure, changes in diuretic therapy, and any unscheduled clinic or
hospital visits

4. Have the ability to provide informed consent for study participation and be willing
and able to comply with the prescribed follow-up tests and schedule of evaluation

Exclusion Criteria:

Patients will be excluded if they meet any of the following:

1. Be less than 18 years of age

2. Have had a recent myocardial infarction, unstable angina or cardiac revascularization
within 40 days of enrollment

3. Have had a recent Cerebrovascular Accident or Transient Ischemic Attack within three
months of enrollment

4. Have a contraindication for an emergency thoracotomy

5. Have an indication that requires programming device in atrial pacing mode

6. Have permanent (chronic) atrial fibrillation

7. Have a capped or inactive right atrial or right ventricular pacing/defibrillator lead

8. Have a hypersensitivity to a single 1.0mg dose of dexamethasone sodium phosphate or
short term contact with heparin

9. Be pregnant or planning a pregnancy in the next 6-months

10. Be currently participating in a clinical investigation that includes an active
treatment arm

11. Have a life expectancy of less than six months due to any condition