"Transmural air leak": a computed tomographic finding following endoscopic submucosal dissection of gastric tumors

BACKGROUND AND STUDY AIMS

A small amount of free air, visible on CT but not on plain chest radiography, which appeared following endoscopic submucosal dissection (ESD) of a gastric neoplasm without endoscopically visible perforation, was defined as a "transmural air leak", and a prospective, consecutive entry study was performed to determine its incidence and clinical significance.

PATIENTS AND METHODS

Between January 2006 and September 2008, ESD was performed for 246 gastric lesions in 246 consecutive patients. Abdominal CT scan was performed 1 day after ESD. In addition, chest radiography and blood biochemistry tests were performed at different time points before and after ESD.

RESULTS

Two hundred and nineteen lesions (89 %) were curatively removed by ESD. Among the total of 246 patients, we encountered endoscopically visible perforation during ESD in 2 patients (0.8 %), and clinically suspected perforation diagnosed by the presence of free air on chest radiography but invisible during ESD in 3 patients (1 %), while transmural air leak was observed in another 33 (13 %). Air leak occurred in cases where resection size was larger, procedure time longer, and the muscularis propria on the ulcer base was exposed at the end of ESD. Patients with air leaks developed pyrexia at a higher rate than those without (36 % vs. 16 %, P = 0.018). These patients recovered with antibiotics and required no endoscopic or surgical intervention. The presence of an air leak did not affect the duration of hospital stay.

CONCLUSIONS

A transmural air leak was observed in 13 % of the patients undergoing ESD. Larger resection size, prolonged procedure time, and exposure of the muscularis propria on the ulcer base were risk factors for transmural air leak, but the outcome of patients with this complication was good.

Multiple endothelial injury in epicardial coronary artery induces downstream microvascular spasm as well as remodeling partly via thromboxane A2

OBJECTIVES

The study was undertaken to develop a coronary microvascular spasm model in pigs by repeated epicardial coronary artery endothelial injury.

BACKGROUND

The pathophysiologic mechanisms responsible for coronary microvascular spasm remain unclear, in large part because a suitable animal model has yet to be found.

METHODS

Balloon endothelial denudation was done just distal to the site of an implanted Doppler flowmeter in the left anterior descending coronary artery (LAD) every two weeks for a total of four times. Changes in LAD blood flow by intracoronary administration of vasoactive agents were assessed before each denudation.

RESULTS

In the epicardial LAD endothelial denudation pigs, decreases in LAD blood flow caused by acetylcholine were augmented. Before denudation, it was - 15 +/- 4%, and at week 8 (i.e., two weeks after the fourth denudation) it was -100% (i.e., zero flow [p < 0.01]). The LAD flow changes in response to 5-hydroxytryptamine (5-HT) changed from an increase to a decrease, accompanied by medial thickening of microvessels in the LAD perfusion area. These flow responses were observed without significant changes in LAD diameter. In contrast, the LAD blood flow responses to acetylcholine and 5-HT did not change throughout the experiment in pigs given aspirin and a thromboxane A2 (TXA2) synthase inhibitor orally.

CONCLUSIONS

This microvascular spasm model indicates that hypersensitivity to vasoactive substances in the microvascular beds as well as microvascular remodeling are brought about partly through TXA2. This model should be useful for examining the pathophysiology and treatment of microvascular angina.

Morphological and functional changes in coronary vessel evoked by repeated endothelial injury in pigs

OBJECTIVE

We examined the morphological changes induced by repeated endothelial denudation in coronary artery (CA), as well as functional changes in the endothelium-dependent and smooth muscle responses to various vasoactive agents during the process of intimal thickening.

METHODS

We observed vascular responses in denuded and non-denuded portions of pig CA while being fed a normal diet (n = 11, N group) or 2% cholesterol diet (n = 25, C group) to intracoronary acetylcholine (ACh), 5-hydroxytryptamine (5-HT), substance P (SP), and isosorbide dinitrate (ISDN) with and without the nitric oxide synthesis inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg i.v.) over a period of 8 weeks. Balloon endothelial denudation of the left anterior descending CA was carried out every 2 weeks.

RESULTS

In N group, maximum vasoconstriction was obtained with ACh 2 weeks after the first denudation [26 +/- 5% vs. 1 +/- 1% pre-denudation, p < 0.05]. L-NAME did not affect ACh-induced CA diameter changes. Thereafter, the response to ACh was attenuated by repeated denudation in N groups. However, the degree of 5-HT-induced CA narrowing at the denuded portion increased from 7 +/- 4% (0 week) to 88 +/- 8% (8 weeks) (p < 0.05). The changes resulted in severe myocardial ischaemia, and suggested that endothelium-dependent vasodilation was progressively attenuated while hyperreactivity of vascular smooth muscle simultaneously increased. Vasodilation induced by SP was attenuated somewhat, but ISDN-induced vasodilation was preserved. Although mild hypercholesterolaemia was induced in C group, the vascular responses to these vasoactive agents did not differ from those of N group.

CONCLUSIONS

Repeated CA endothelial injury and regeneration induce the change of morphology and vascular reactivity in the denuded portion regardless of atherogenic diet. This study strongly suggests that intimal thickening caused by repeated endothelial injury and regeneration induces specific vascular responses to vasoactive agents. Moreover, it is also suggested that during the progression of intimal thickening, increased vascular smooth muscle contraction and decreased endothelium-dependent dilation appear in a stimulus-dependent manner, often leading to severe coronary vasoconstriction accompanied with definitive ECG ST change.