Endosonographic Doppler-guided manometry of esophageal varices: experimental validation and clinical feasibility

The risk of variceal bleeding cannot be accurately predicted using endoscopy alone. Although variceal pressure has been demonstrated to be a major determinant for the rupture of esophageal varices, direct determination by needle puncture is unsuitable for routine clinical use. Due to their operator-dependency, current noninvasive endoscopic methods for determination of variceal pressure have not gained wide acceptance. We have developed a new method of measuring variceal pressure, using endoscopic power Doppler imaging to monitor the manometry of esophageal varices. The aims of this study were to test in vitro the accuracy of Doppler-guided manometry and to assess the clinical feasibility of this method.

Experimental validation of this technique was performed using an in vitro model of artificial varices of different sizes. A linear-array endosonography (EUS) probe with power Doppler capability was used to assess flow in the varices and a balloon for manometry of esophageal varices was attached to the tip of the probe. Pressure readings were made at the time of disappearance of the Doppler signal during variceal compression by the balloon. Linear regression analysis was used to compare the results of Doppler-guided and direct intraluminal pressure measurement in the artificial varices. Variceal pressure was then measured with this technique in 28 patients with portal hypertension and esophageal varices without previous bleeding, and the results were compared with portal pressure assessed according to the hepatic vein pressure gradient (HVPG).

In vitro studies demonstrated a good correlation between the pressure measured with Doppler monitoring and the actual intravariceal pressure (r > or = 0.922; P < 0.001). The determination of variceal pressure with this method was technically successful in 26/28 patients (93 %). The intraoperator variance was 9.3 +/- 8.6 %. Overall, the mean variceal pressure was significantly lower than the mean HVPG (21.2 +/- 5.3 mmHg vs. 24.3 +/- 7.8 mmHg; P < 0.01). Variceal pressure and portal pressure (as assessed by the HVPG) correlated significantly (r = 0.64; P < 0.001).

Our preliminary results indicate that EUS Doppler-guided manometry of esophageal varices is feasible and accurate. This technique may become a more reliable method for noninvasive measurement of variceal pressure and warrants further investigation.