Direct Ascending Pharyngeal Artery to Jugular Vein Arteriovenous Fistula

A 32-year-old female developed a bruit, determined to arise from a rare direct arteriovenous (AV) fistula from the ascending pharyngeal artery to the internal jugular vein. The fistula was treated by transarterial silicone balloon occlusion, with occlusion of fistulous flow, ablation of symptoms, and excellent long-term result.

Validation of Air as an Equilibration Medium in Gastric Tonometry: An in Vitro Evaluation of Two Techniques for Measuring Air Pco2

This laboratory-based bench study was undertaken to evaluate the accuracy and equilibration characteristics of air and saline respectively as CO2 equilibrating media in the silicone balloon of a gastric tonometer and to compare two methods of measuring air Pco2. Two gastric tonometers were suspended in a bath containing 0.9% saline maintained at 37°C. Certified calibration gases at three different CO2 concentrations were bubbled into the bath. When the bath Pco2 measurement was stable the tonometers were primed with 5 ml of air and 2.5 ml normal saline respectively and allowed to equilibrate for 30 and 90 minutes. Following equilibration, samples were aspirated and analysed in duplicate in a blood gas analyser. Bias and precision were calculated from the measured and expected Pco2 values. A consistent negative bias (21–23%) was seen with air at all three CO2 concentrations at 30 and 90 minutes with a coefficient of variation between 2.7 and 3.3%. Imprecise data were obtained with saline at different levels of CO2. A similar experimental set-up was used to compare air Pco2 measurement by a blood gas analyser and an infra-red analyser (Tonocap). Similar bias was obtained with the blood gas analyser with respect to air Pco2 measurement as in experiment 1. The infra-red analyser measurement was highly precise with negligible bias. Air appears to be a better CO2 equilibration medium during bench testing of tonometry producing a systematic negative offset and requiring a uniform correction factor of 1.25. This correction factor is independent of equilibration time and equilibrating CO2 concentration. The use of the infra-red analyser eliminates any bias in the measurement of air Pco2 and obviates the need for a correction factor.

Aneurysm recurrence following endovascular balloon occlusion

✓ Endovascular balloon occlusion is an alternative treatment for surgically unclippable cerebral aneurysms. The results of aneurysm occlusion with either a silicone or a latex balloon in a common carotid artery bifurcation aneurysm model are compared to determine which type of balloon was least likely to result in aneurysm recurrence. Five rabbits each underwent endovascular balloon occlusion with either a silicone or a latex balloon, with seven rabbits serving as controls. At 3 months postocclusion, nine of the 10 balloon-treated aneurysms had recurred. The recurrent aneurysm tended to be larger in animals treated with silicone than with latex balloons. A dense fibrotic response was present around the collar of the latex balloons, but no significant fibrotic response was found in the silicone balloon group. This study suggests that with currently available balloons, the initial complete angiographic obliteration of an aneurysm following balloon occlusion should not be interpreted as a cure and that periodic follow-up angiography should be performed.

Persistent Primitive Trigeminal Artery-Cavernous Sinus Fistulas: Report of Two Cases

Two cases of persistent Primitive trigeminal artery-cavernous sinus fistulas are presented. In one case, the fistula was treated by using a two-balloon tandem technique. This method was accomplished by introducing, inflating, and detaching a silicone balloon into the trigeminal artery, thus preserving the carotid and basilar blood flow. An unusual case of a similar fistula with only contralateral exophthalmos is also reported. The relationship between this type of fistula and the presence of aneurysms on the persistent primitive trigeminal artery and the relationship with traumatic events are discussed.