InterventiOn of Biventricular Pacemaker Function on ventrIcular Function Among Patients With LVAD's

15 patients with advanced HF who have already undergone CF-LVAD implantation.

Inclusion criteria:

1. Have already received CF-LVADs and are clinically stable,

2. Ambulatory outpatients and are fully recovered (at least 3 months) from LVAD
implantation;

3. Presence of a cardiac resynchronization therapy defibrillator (CRT-D) with an
underlying LBBB conduction abnormality.

Exclusion criteria:

1. Individuals with clinical RV failure under resting conditions, defined as
moderate-severely reduced RV systolic function on echocardiography, or

2. Clinical evidence of RV failure (elevated jugular venous pressures, 3 or 4+
[significant] peripheral edema);

3. Disorders that adversely influence exercise ability (e.g. arthritis, peripheral
vascular disease, pulmonary disease); and

4. Patients that do not have a CRT-D device.

10 healthy individuals will serve as a control group to define normal RV function during
exercise.

Inclusion criteria:

1) Persons without a past medical history of cardiovascular disease or related disease such
as:

1. hypertension,

2. diabetes,

3. peripheral vascular disease,

4. arrhythmias,

f. are not taking any cardiac-related medications (e.g. antihypertensive medications).

Exclusion criteria:

1. Individuals requiring systemic anticoagulation with vitamin-K antagonists or
new/direct oral anticoagulants ("NOAC"/"DOAC");

2. Disorders that adversely influence exercise ability (e.g. arthritis, peripheral
vascular disease).