Biomedical subjects

Mark H Johnston

Publications and source records attributed to Mark H Johnston.

4 recordsLinked to original sources

PubMed2005

Cryoablation of Barrett's esophagus: a pilot study.

BACKGROUND: Numerous ablative modalities have demonstrated varying degrees of efficacy in the eradication of Barrett's esophagus (BE). However, they are associated with either high cost, patient discomfort, complications, tedious application, residual underlying BE, or some combination of the above. The aim of this study was to evaluate the safety and the efficacy of a new cryogenic device by using liquid nitrogen sprayed through an open tipped cryogenic catheter placed through the accessory channel of an upper endoscope. METHODS: A prospective, single center study was performed on patients with a long-standing history of BE followed in a Barrett's registry. Patients with degrees of dysplasia ranging from none to multifocal high-grade dysplasia were treated. All patients were treated with 40 mg rabeprazole 3 times per day during the treatment period. Elimination of acid reflux was confirmed via 24-hour esophageal pH studies. Cryoablation was applied hemicircumferentially to 4-cm-long segments at monthly intervals, until the entire segment of BE was eliminated. RESULTS: Eleven patients were treated. There was reversal of BE in all patients. In 9 of 11 (78%) patients who completed the protocol, there was complete endoscopic and histologic reversal of BE. There was no subsquamous specialized intestinal metaplasia at the 6-month follow-up. No complications occurred. CONCLUSIONS: Based on preliminary results, low-pressure spray cryoablation of BE under direct endoscopic visualization is safe and easy to perform. Its relative lack of patient discomfort and its simplicity and demonstrated efficacy make it a modality that should be further explored in the ablation of GI mucosal lesions such as BE and perhaps early esophageal cancer.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed2005

Technology insight: ablative techniques for Barrett's esophagus--current and emerging trends.

New mucosal ablative techniques that can be used in the esophagus have emerged over the past two decades. These techniques have been developed primarily to treat the precursors of esophageal adenocarcinoma: dysplasia in Barrett's esophagus and early esophageal cancer. Although high-grade dysplasia and early stage cancer can be treated with esophagectomy, the inherent morbidity and mortality of esophageal adenocarcinoma and the morbidities, difficulties, costs and limitations of the current technology mean that there has been a significant increase in interest and research regarding alternative treatments such as ablative techniques. At this stage it is not clear which of the numerous endoscopic ablative techniques available-photodynamic therapy, laser therapy, multipolar electrocoagulation, argon plasma coagulation, endoscopic mucosal resection, radiofrequency ablation or cryotherapy-will emerge as superior. In addition, it has yet to be determined whether the risks associated with ablation therapy are less than the risk of Barrett's esophagus progressing to cancer. Whether ablation therapy eliminates or significantly reduces the risk of cancer, eliminates the need for surveillance endoscopy, or is cost-effective, also remains to be seen. Comparative trials that are now underway should help to answer these questions.

Adenocarcinoma↗

PubMed2005

Technology insight: ablative techniques for Barrett's esophagus--current and emerging trends.

New mucosal ablative techniques that can be used in the esophagus have emerged over the past two decades. These techniques have been develop primarily to treat the precursors of esophageal adenocarcinoma: dyspla, in Barrett's esophagus and early esophageal cancer. Although high-grade dysplasia and early stage cancer can be treated with esophagectomy, the inherent morbidity and mortality of esophageal adenocarcinoma and the morbidities, difficulties, costs and limitations of the current technology mean that there has been a significant increase in interest and research regarding alternative treatments such as ablative techniques. At this stage it is not clear which of the numerous endoscopic ablative techniques available---photodynamic therapy, laser therapy, multipolar electrocoagulation, argon plasma coagulation, endoscopic mucosal resection, radiofrequency ablation or cryotherapy--will emerge as superior. In addition, it has yet to be determined whether the risks associated with ablation therapy are less than the risk of Barrett's esophagus progressing to cancer. Whether ablation therapy eliminates o significantly reduces the risk of cancer, eliminates the need for surveillance endoscopy, or is cost-effective, also remains to be seen. Comparative triads that are now underway should help to answer these questions.

Barrett Esophagus↗

PubMed2003

Cryotherapy and other newer techniques.

Potential modalities for the ablation of Barrett's mucosa are increasing with new technologies. Three of the newest are high- and low-pressure spray cryotherapy and ultrasonic epithelial ablation. Data regarding low-pressure spray cryotherapy are particularly promising. It has a depth of ablation approximating 2 mm, is technically easy to perform, and involves unique cellular mechanisms of injury relative to other thermal techniques that may prove ideally suited for the treatment of GI neoplasms and premalignant lesions such as Barrett's esophagus. A Barrett's ablation trial with cryotherapy is ongoing at the National Naval Medical Center.

Animals↗