VVIR 80-130 Pacing Mode Explanation
VVIR 80-130 refers to a ventricular rate-responsive pacing mode where the pacemaker stimulates only the ventricle, senses ventricular activity, is inhibited by sensed ventricular events, and can increase the heart rate from 80 to 130 beats per minute in response to physical activity or metabolic demand. 1
Understanding the VVIR Code Components
- V (first position): Indicates that pacing occurs only in the ventricle 1
- V (second position): Indicates that sensing occurs only in the ventricle 1
- I (third position): Indicates that the pacemaker is inhibited by sensed ventricular activity 1
- R (fourth position): Indicates rate-responsive functionality, allowing the pacemaker to adjust heart rate based on physiological needs 1
- 80-130: The rate range, with 80 beats per minute as the lower limit and 130 beats per minute as the upper limit 2
How VVIR Pacing Works
- The pacemaker continuously monitors the ventricle for intrinsic electrical activity 1
- If no ventricular activity is detected within the programmed interval (corresponding to 80 bpm), the pacemaker delivers a stimulus to the ventricle 1
- If intrinsic ventricular activity is detected, the pacemaker is inhibited and does not deliver a stimulus 1
- The rate-responsive feature uses sensors (typically activity or metabolic) to detect increased physical activity or physiological demand 1
- During increased activity, the pacing rate automatically increases up to the maximum programmed rate (130 bpm) 2, 3
- When activity decreases, the pacing rate gradually returns to the lower rate (80 bpm) 3
Clinical Applications of VVIR Pacing
- Primary indication: Patients with chronotropic incompetence (inability to appropriately increase heart rate during activity) 1
- Appropriate for: Patients with symptomatic bradyarrhythmias, especially with persistent or paroxysmal atrial fibrillation 1
- Particularly useful in: Patients where pacing simplicity is a concern (elderly, terminal disease, remote location) 1
- Demonstrated benefits: Significant improvement in exercise capacity compared to fixed-rate pacing 3, 4
Important Considerations and Limitations
- Contraindicated in: Patients with known pacemaker syndrome or when symptoms occurred during temporary ventricular pacing 1
- Use with caution in: Patients with retrograde VA conduction, as VVIR can exacerbate angina pectoris or congestive heart failure at faster rates 1
- Lacks AV synchrony: Unlike dual-chamber pacing modes, VVIR does not maintain coordination between atrial and ventricular contractions 5, 6
- Hemodynamic implications: May result in lower cardiac output compared to modes that maintain AV synchrony, particularly during exercise 5, 6
Practical Clinical Relevance
- The 80-130 range is specifically programmed to prevent bradycardia (below 80 bpm) while limiting the maximum heart rate (to 130 bpm) to avoid excessive rates that could be harmful 2, 3
- This rate range is commonly used in patients with cardiac conditions where excessive heart rates could be detrimental 7
- The upper rate limit (130 bpm) helps prevent pacemaker-mediated tachycardia that could worsen cardiac conditions 7