An improved in vivo method for atrioventricular node ablation via thoracotomy.
R H Maciver1, R D Stewart, C L Backer
1Division of Cardiovascular-Thoracic Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
Summary
Researchers developed an improved animal model for complete heart block (CHB) by refining surgical techniques and using a novel injection device for precise atrioventricular (AV) node ablation. This model aids in testing new therapies for CHB before human trials.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Animal Models
Background:
- Permanent pacemaker implantation is required in ~3% of congenital heart surgery due to atrioventricular (AV) node damage.
- Effective in vivo models are crucial for developing and testing new treatments for complete heart block (CHB).
Purpose of the Study:
- To describe an improved in vivo model for inducing chronic AV block, mimicking surgical pathology.
- To enable accurate, reliable, and detectable induction of CHB for preclinical research.
Main Methods:
- A novel surgical approach in adult rabbits involving right thoracotomy and AV node access.
- Development of a specialized injection device with depth restriction and ECG guidance for precise formalin ablation of the AV node.
- Real-time electrocardiogram (ECG) monitoring to confirm AV node contact and document ablation.
Main Results:
- All animals achieved acute AV block.
- Animals with ECG guidance demonstrated a higher likelihood of maintaining chronic heart block (>12 hours).
- The model successfully reproduced CHB and associated peripheral fibrosis, relevant to congenital heart surgery.
Conclusions:
- The improved rabbit model provides a reliable method for inducing chronic AV block and associated fibrosis.
- This model is suitable for evaluating tissue-engineered therapies and pacemaker designs for CHB.
- Enhanced precision and documentation through the novel injection device improve model reproducibility.
