Inclusion Criteria:
1. Male or female, ≥ 18 years of age at enrolment
2. Subject who has a Class I or II indication for implantation of a single chamber ventricular pacemaker according to ACC/AHA/HRS/EHRA guidelines:
* Paroxysmal or permanent high-grade AV block in the presence of Atrial Fibrillation (AF)
* Paroxysmal or permanent high-grade AV block in the absence of AF, as an alternative to dual chamber pacing, when dual chamber transvenous pacing system is considered difficult, elevated risk, or not deemed necessary for effective therapy.
* Symptomatic bradycardia-tachycardia syndrome or Sinus Node Dysfunction (sinus bradycardia or sinus pauses), as an alternative to atrial or dual chamber pacing, when dual chamber transvenous pacing system is considered difficult, elevated risk, or not deemed necessary for effective therapy.
3. Subject able and willing to undergo the study requirements and is expected to be geographically stable for the duration of the follow-up.
4. Subject with a life expectancy of more than 24 months.
5. Subject is able and willing to use the Home Monitor.
6. Written informed consent to participate in the study obtained from the subject, according to local regulations, prior to initiation of any study mandated procedure.
Exclusion Criteria:
1. Subject who is entirely pacemaker dependent (escape rhythm \<30 bpm).
2. Subject has an existing or prior pacemaker, ICD, or CRT device implant.
3. Subject has unstable angina pectoris or has had an acute myocardial infarction (AMI) in the 30 days prior to eligibility assessment.
4. Subject had recent cardiovascular or peripheral vascular surgery within 30 days prior to enrollment
5. Subject with current implantation of a neurostimulator or any other chronically implanted device which uses current in the body. Note that a temporary pacing wire is allowed.
6. Subject with a prior intervention of the tricuspid valve, implanted vena cava filter that cannot be crossed, or left ventricular assist device (LVAD).
7. Subject who is morbidly obese (BMI \> 40).
8. Subject who has a below normal BMI (BMI\<18).
9. Subject whose femoral venous anatomy is unable to accommodate a 24 French introducer sheath or an implant on the right side of the heart (for example, due to obstructions or severe tortuosity) in the opinion of the implanter.
10. Subject with ventricular dysfunction and LVEF ≤ 50
11. Subject who is considered as unable to tolerate an urgent sternotomy.
12. Subject with a known intolerance to Titanium, titanium nitride, parylene C, PEEK, platinum-iridium alloy, heparin, or sensitivity to contrast media.
13. Subject for whom a single dose of 1.0 mg dexamethasone acetate may be contraindicated.
14. Subject with a life expectancy of less than 24 months.
15. Subject with significant co-morbid conditions or other conditions which, at the discretion of the PI, are deemed to prohibit study entry
16. Subject who is currently enrolled or planning to participate in a potentially confounding drug or device trial during the course of this study. Co-enrollment in concurrent trials is only allowed when documented preapproval is obtained from the Cairdac study manager.
17. Pregnant woman, or woman of childbearing potential and who is not on a reliable form of birth control.
18. Subject with exclusion criteria required by local law (e.g. age, breast feeding, etc.).
