Changes in Regional Ventilation-Perfusion Match Following Percutaneous Transluminal Angioplasty for Arteriovenous Graft Thrombosis

Arteriovenous graft (AVG) thrombosis is a major source of vascular access failure in ESRD. PTA restores patency through balloon dilation and mechanical thrombus compression. Minor embolic debris can reach the pulmonary bed, transiently disturbing perfusion distribution and V/Q matching. Because the pulmonary circulation is sensitive to sudden peripheral hemodynamic shifts, the PTA period provides a unique opportunity to observe lung perfusion response dynamically.

This single-center, prospective, observational pilot study will continuously record regional ventilation and perfusion by EIT at six time points: 10 min before PTA, at recanalization, and 10, 20, 30 min after, and at procedure completion. Measured variables include: V/Q matching index (primary), physiological dead space fraction (Vd/Vt), intrapulmonary shunt fraction, SPO₂/FiO₂ ratio, and hemodynamic data (balloon pressure, recanalization time, blood flow recovery). Results will be analyzed using repeated-measures ANOVA or mixed-effects modeling.

• Electrical Impedance Tomography (EIT) Monitoring (Diagnostic test): Non-invasive 16-electrode EIT belt applied at the 4th intercostal level. Continuous data acquisition begins 10 min pre-PTA, continues throughout balloon angioplasty, and up to 30 min post-recanalization. No alteration to standard clinical care.

Primary outcomes

• Change in Ventilation-Perfusion Matching Index [Baseline (10 min before PTA), immediate post-recanalization, 10, 20, 30 minutes, and procedure end.]: Quantitative index derived from EIT ventilation and perfusion maps, indicating spatial regional correlation of air and blood flow distribution.

Secondary outcomes

• Change in Peripheral Oxygen Saturation [Baseline (10 min before PTA), immediate post-recanalization, 10, 20, 30 minutes, and procedure end.]
• Change in Physiological Dead Space Fraction [Baseline (10 min before PTA), immediate post-recanalization, 10, 20, 30 minutes, and procedure end.]: Ratio of physiologic dead space to tidal volume, calculated by EIT validated algorithm, reflecting inefficiency of ventilation.
• Change in Intrapulmonary Shunt Fraction [Baseline (10 min before PTA), immediate post-recanalization, 10, 20, 30 minutes, and procedure end.]: Percentage of the lung region showing perfusion without ventilation, estimated from EIT perfusion signals.
• Change in Regional Ventilation and Perfusion Distribution [Baseline (10 min before PTA), immediate post-recanalization, 10, 20, 30 minutes, and procedure end.]: Variation in spatial patterns of pulmonary ventilation and perfusion derived from pixel-based EIT data.

Sex: All, ages: 18 Years to any

Inclusion Criteria

1. Age ≥ 18 years.
2. Diagnosis of end-stage renal disease receiving maintenance hemodialysis.
3. Documented AVG thrombosis requiring PTA.
4. Able to cooperate and tolerate EIT monitoring.
5. Provided written informed consent.

Exclusion Criteria

1. Severe respiratory failure incompatible with supine position.
2. Thoracic skin condition or deformity preventing EIT electrode placement.
3. Acute pulmonary embolism or acute pulmonary edema before procedure.
4. NYHA Class IV heart failure or hemodynamic instability.
5. Pregnancy or breastfeeding.
6. Any other circumstance judged unsuitable by investigator.