Objectives: Spray cryotherapy (SCT) delivers a liquid nitrogen spray via a catheter to produce cellular death. This study seeks to determine the histological changes after bronchoscopic, endoscopic and open SCT on tissues in the thoracic cavity.
Methods: Yorkshire pigs underwent flexible bronchoscopy, endoscopy and thoracotomy for SCT of the airway, oesophagus and other intrathoracic structures, respectively. Variations in the duration and number of spray cycles for the same dosimetry were compared.
Results: Bronchoscopic SCT of the airway resulted in cellular death up to the cartilage layer. Endoscopic SCT of the oesophagus led to cell death up to the adventitial layer. Tissue necrosis was severe in the lung, of full thickness in the pleura, but very superficial in the great vessels. The extracellular matrix (ECM) of treated tissues remained well-preserved. Having shorter but more cycles of SCT decreased the depth of the cellular necrosis. One pig developed ventricular fibrillation during the surgery and expired.
Conclusions: SCT causes reproducible tissue injury with the preserved ECM of most tissues within the thoracic cavity, making it enticing for ablation around vital structures like the great vessels with a decreased long-term risk. Further study is warranted to investigate the adverse events during SCT.