In vivo comparison of esophageal varices at and above the diaphragmatic high pressure zone using high resolution endoluminal sonography.

Our objective in this study was to use high resolution endoluminal sonography to compare the size of esophageal varices within 5 cm of and at the esophageal high pressure zone. We carried out the study in 36 patients with endoscopically proven esophageal varices. A 20-MHz 6.2F ultrasound catheter was passed through a 34F endoscope and used to image esophageal varices as it was slowly withdrawn through the high pressure zone (the level at which the diaphragm was imaged) and into the body of the esophagus approximately 5 cm above the high pressure zone. All images were captured on videotape and reviewed by one of the investigators. The mean, total, and percent cross-sectional surface areas occupied by varices were calculated and then compared within 5 cm and at the esophageal high pressure zone. Six of 36 (17%) patients had no varices imaged at the high pressure zone but did have varices imaged in the distal esophagus. The mean cross-sectional surface area per varix at the high pressure zone (0.036+/-0.006 cm2) was significantly less (p < or = 0.0001) than the mean cross-sectional area per varix 5 cm above the high pressure zone (0.142+/-0.018 cm2). The average total cross-sectional surface area occupied by varices at the high pressure zone (0.137+/-0.034 cm2) was significantly less (p < 0.0001) than the average cross-sectional surface area occupied by varices 5 cm above the high pressure zone (0.672+/-0.080 cm2). The mean percent esophageal wall cross-sectional surface area occupied by varices at the high pressure zone (16%) was significantly less (p < or = 0.0001) than 5 cm above the high pressure zone (49%). We conclude that the mean, total, and percent cross-sectional surface areas of esophageal varices at the high pressure zone are significantly less than those 5 cm above the high pressure zone.

Use of high-resolution endoluminal sonography to measure the radius and wall thickness of esophageal varices.

BACKGROUND: Measurement of variceal wall tension theoretically provides the most accurate method of predicting future variceal bleeding. Using high-resolution endoluminal sonography in 45 patients with known portal hypertension, we measured and correlated the two previously unmeasured variables involved in the calculation of variceal wall tension (radius and wall thickness) by the Laplace equation. METHODS: A 20 MHz 6.2F ultrasound transducer was used to image esophageal varices during standard esophagoscopy. All images were captured on videotape and later reviewed by two blinded investigators. Outer and inner variceal wall circumferences were measured at a cross section of each varix. The radius of each varix and the variceal wall thickness were calculated. The radius of each varix was then correlated with its wall thickness. The interobserver and intraobserver variabilities were measured. RESULTS: The mean variceal radius was .86 +/- .34 cm for the inner radius and 1.48 +/- .41 cm for the outer radius; mean variceal wall thickness was .099 +/- 0.037 cm. Intraobserver and interobserver correlation for the radius was r = .98 and r = .97, respectively. The intraobserver and interobserver correlations for the wall thickness were r = .92 and r = .91, respectively. Variceal radius did not correlate with the wall thickness of the varix. CONCLUSIONS: High-resolution endoluminal sonography provides a method for the accurate measurement of esophageal variceal radius and wall thickness. Variceal radius does not correlate with variceal wall thickness, implying that variceal wall tension cannot be accurately estimated by measurement of variceal size alone. Combining these data with measurements of variceal pressure should allow for the direct determination of wall tension and, subsequently, identification of patients at risk for variceal bleeding.

High-resolution endoluminal sonography in achalasia.

BACKGROUND: Imaging of the lower esophageal sphincter in patients with achalasia using 7.5 and 12 MHz ultrasound transducers has shown variable results. METHODS: A 20 MHz radial ultrasound transducer was used to quantitatively compare the lower esophageal sphincter in patients with achalasia to that of normal volunteers. The transducer, housed in a 6.2F catheter, was placed at the level of the lower esophageal sphincter in 29 patients with achalasia and 19 normal subjects. Videotaped images from the lower esophageal sphincter were digitized and the width of the circular smooth muscle, longitudinal smooth muscle, and total muscularis propria were measured. A mean width for each muscle layer was calculated. RESULTS: All muscle layers were found to be significantly thickened at the lower esophageal sphincter in patients with achalasia when compared with those in normal subjects: circular smooth muscle (0.206 cm +/- 0.137 cm vs 0.124 cm +/- 0.038 cm, p < 0.017); longitudinal smooth muscle (0.128 cm +/- 0.077 cm vs 0.088 cm +/- 0.028 cm, p < .041); and total muscle thickness (0.317 +/- 0.180 cm vs 0.224 cm +/- 0.049 cm, p < 0.033). CONCLUSION: Although high-resolution endoluminal sonography cannot be used to differentiate patients with achalasia from normal controls, this study quantitatively demonstrates that both the mean longitudinal and mean circular smooth muscle layers at the lower esophageal sphincter are wider in patients with achalasia than in a group of normal subjects.