The goal of this clinical trial is to establish the safety, feasibility, and preliminary findings of overground robotic exoskeleton early ambulation (ORE-EA) compared to usual care early ambulation (UC-EA) in the rehabilitation of patients who have had cardiovascular or thoracic surgery. The main questions it aims to answer are:

• Is there a difference between groups in time between surgery and ambulation?
• Are there differences in safety and feasibility?

Inclusion Criteria:

1. Age ≥ 18 years
2. Underwent cardiovascular or thoracic surgery, including but not limited to coronary artery bypass grafting, valve replacement/repair, lung resection, or advanced cardiovascular or pulmonary therapies [transplant, durable or temporary ventricular assist device implantation (VAD), temporary mechanical circulatory support (tMCS), venovenous extracorporeal membrane oxygenation (VV ECMO)].
3. Medically appropriate for physical therapy, including upright activity and ambulation, as defined by an order in the patient's electronic medical record signed by a physician or advanced practice provider.
4. Requires ≥ 50% assist to perform upright activity based on physical therapy assessments (e.g., AMPAC-6 clicks or JH-HLM)
5. English or Spanish-speaking
6. Able to provide written informed consent (or via a legally authorized representative if applicable)
7. Meets ORE frame limitations (height = 5'2" to 6'4" and weight ≤ 220 lbs.)

Exclusion Criteria:

1. Cognitive or behavioral impairment that interferes with safe participation [e.g., active delirium (positive CAM-ICU score) or unable to follow commands].

2. Moderate vasopressor or inotrope requirements, including:

   >0.10 mcg/kg/min of norepinephrine >0.03 mcg/kg/min of epinephrine >80.0 mcg/kg/min of phenylephrine >0.04 units/min of vasopressin >5.0 mcg/kg/min of dobutamine >5.0 mcg/kg/min dopamine >0.50 mcg/kg/min of milrinone Any combination of > 3 of any of these, regardless of dose, unless deemed acceptable at the discretion of the treating attending.

3. Sustained ventricular arrhythmias that require intervention at the time of upright mobilization.

4. Any active dose of angiotensin II

5. Positive end-expiratory pressure (PEEP) ≥ 10 cm H20).

6. Except for those with a femoral arterial balloon pump, all patients with existing femoral arterial lines at the time of ambulation are ineligible. However, patients with femoral intraortic balloon pump (IABP) may be considered if, in the judgment of the attending physician and physical therapy team, patient is appropriate for ambulation given patient's clinical status and IABP site and securement status, and if ambulation of appropriate patients with femoral IABP is consistent with local standard of care at the time of ambulation.

7. Skin disintegrity in proximity to the ORE frame

8. Participation in another interventional study that may confound outcome measures.

9. Pregnancy

10. Any other condition that, in the judgment of the clinical or research team, would pose an unacceptable risk or interfere with study participation or interpretation.

There currently is no plan to share IPD