The investigators hypothesize that chronic heart failure is associated with a general stem cell dysfunction, which translates into reduced paracrine function of adult stem cells from patients with chronic heart failure as compared to patients with preserved systolic function.

Inclusion Criteria:

For all participants:

1. Before any study-specific procedures, the appropriate written informed consent must be obtained.

2. Male and female older than 18 years of age.

   For the cardiac patients:

3. Being accepted for cardiothoracic surgery with the use of open chest surgery

4. A known left ventricular ejection fraction, either assessed by echocardiography, MUGA or MRI. If LVEF <40% a subject will be assigned to the chronic heart failure group, if LVEF >40% a subject will be assigned to the control group.

   For the non-cardiac patients:

5. Accepted for orthopedic surgery (e.g. total hip replacement) at the department of orthopedic surgery.

Exclusion Criteria:

1. An unstable medical condition, defined as having been hospitalized for a non-cardiac condition within 4 weeks of screening, or otherwise unstable in the judgment of the investigator (e.g. at risk of complications or adverse events unrelated to study participation).

2. Younger than 18 years of age.

3. Clinical history of chronic kidney disease (at any point prior to registration).

4. Any known hepatic disease.

5. Recent (within 3 months) history of alcohol or illicit drug abuse disorder, based on self-report.

6. Clinically significant abnormality in chemistry, hematology, or urinalysis parameters performed within the screening period.

7. Participation in any investigational device or drug trial(s) or receiving investigational agent(s) within 30 days.

8. Any condition (e.g. psychiatric illness, etc.) or situation that, in the investigator's opinion, could put the subject at significant risk, confound the study results, or interfere significantly with the subject's participation in the study.

9. Legally incompetent adults, for which reason what so ever.

   For the non-cardiac patients:

10. A known history of cardiovascular disease.

Man and woman, undergoing cardiothoracic surgery, older than 18 years of age, with and without preserved left ventricular ejection fraction (LVEF <40% and >40%). Controls are man and women, older than 18 years of age, scheduled for orthopaedic surgery without a history of cardiac disease.