[Experiences with the use of an intravascular 6 French endosonography catheter in vivo]

Endoneurosonography: technique and equipment, anatomy and imaging, and clinical application

OBJECTIVE

To evaluate the usefulness of transendoscopic ultrasound in neurosurgery, we studied two new sonoprobes measuring 6 and 8 French in diameter in 20 fresh specimens. The application and indication are discussed in the first clinical series of 75 patients.

METHODS

Sonocatheters (ALOKA, Meerbusch, Germany) 1.9 mm (6 French) and 2.4 mm (8 French) in diameter were introduced into the working channel of an endoscope. The preparations were done in nonfixed skulls in a surgical simulation-setting laboratory. Based on these experiences with imaging possibilities, intraoperative transendoscopic ultrasound was applied in 75 patients and a variety of lesions. It was used for imaging (41 patients), targeting (18 patients), and neuronavigation (16 patients) in neuroendoscopy.

RESULTS

The sonoprobe adds a transverse scan at the tip of the probe to the anterior endoscopic view. This axial scan to the longitudinal axis of the endoscope is geometrically comparable with radar scanning. Three probes working with 10, 15, and 20 MHz were used, resulting in a short penetration with a radius of 3 cm. The orthogonal scanning plane had limitations, which were documented. We observed precise imaging of well known anatomic structures and, moreover, achieved an additional dimension in endoscopy. The axial scan presents the anatomic landmarks like a map at the tip of the endoscope where the endoscope is represented as a spot. The real-time imaging and representation of the tip of the endoscope showed a capacity for navigation. This preclinical study rectified clinical application. The real-time imaging of this technique showed the ability of the navigation of endoscopes to detect more overall movements, such as blood flow or change of ventricle size during endoscopy. The primary benefit in this first clinical series was witnessed in difficult endoscopy cases and complex lesions, but benefit was also observed in cases in which vision through the endoscope alone was obscured. The main limitation was the result of little penetration depth and lack of anterior scanning.

CONCLUSION

Application of transendoscopic ultrasound is appropriate in neurosurgery. Training is necessary to understand the imaging and the geometry of scans because this technique does not scan along the axis of the endoscope. Further development to overcome the current limits of this technique and more clinical experience are needed.

ENDOSCOPIC ULTRASOUND INSTRUMENTATION, APPLICATIONS IN HUMANS, AND POTENTIAL VETERINARY APPLICATIONS

Endoluminal scanning under endoscopic guidance, or endoscopic ultrasonography (EUS), has become the most significant advance for imaging the gastrointestinal (GI) tract wall and contiguous organs in the past 20 years. It was originally designed to overcome the limitations in humans to imaging the abdominal organs transabdominally, such as large penetration depths and GI air. This imaging modality provides detailed images of pathological processes both within and outside of the GI wall since a high-frequency transducer can be brought into close proximity with the target regions. It has found most success in humans for the staging of lung, gastric, and esophageal cancer, the detection of both lymphatic and hepatic metastases, and diagnosis of pancreatitis and pancreatic cancer, as well as achieving an important role in interventional and therapeutic procedures. The EUS examination can be performed to examine both the thorax and abdomen in animals when both conventional transthoracic or transabdominal ultrasound are inadequate due to intervening air, bone, large penetration depths, or obesity. The echoendoscope is similar to a conventional endoscope but has an ultrasound transducer at its tip. Both radial and linear multifrequency scanners are available. Linear scanners allow fine-needle aspiration (FNA) of the bowel wall or extraluminal structures. Transducer coupling is either by direct mucosal contact or by inflation of a water-filled balloon surrounding the transducer. Current thoracic applications for EUS in veterinary medicine include examination of the mediastinum, bronchial lymph nodes, esophagus, and pulmonary lesions as well as FNA of pulmonary masses. Abdominal applications include examination of both pancreatic limbs and the liver, including portosystemic shunts, detection of lymphadenomegaly, and examination of the gastric wall, duodenum, and jejunum. Other potential applications in dogs and cats include tumor staging and intrapelvic ultrasound.

Effect of high dose verapamil on restenosis after peripheral angioplasty

OBJECTIVES

We sought to determine whether treatment with high dose verapamil prevents restenosis in patients at high risk for reoccurrence after successful percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Restenosis is the major limitation of PTCA. Calcium antagonists have demonstrated some potential as inhibitors of this process.

METHODS

A total of 98 patients with peripheral occlusive arterial disease (POAD), stable angina pectoris, mild hypertension and at least one additional risk factor increasing the likelihood of restenosis after angioplasty were selected for this placebo-controlled, double-blind, randomized trial. Verapamil (240 mg twice daily) or placebo was taken for 6 months. Efficacy variables assessed before and after angioplasty and at 6 weeks and 6 months after PTCA included thickness of the intima/media complex degree of stenosis, interventricular septal thickness, crurobrachial pressure ratios of dorsalis pedis and posterior tibial arteries, distance to claudication and total vessel diameter.

RESULTS

No significant intergroup differences emerged before or immediately after PTCA. Six weeks after angioplasty, a significant thickening of the intima/media complex in the treated vascular segment of 14.3% occurred in the placebo group versus 0% among verapamil patients (p < 0.01). At 6 months, the intima/media thickness was 35.7% greater in the placebo group but had decreased by 14.3% in the verapamil group (p < 0.001). At 6 months, a marked reduction in septal thickness was observed in the verapamil group versus that in the placebo group (p < 0.001). The rate of restenosis was also significantly lower in the verapamil group (p < 0.001). Few minor side effects were reported.

CONCLUSIONS

In patients with POAD at increased risk for restenosis, the administration of high dose verapamil prevented recurrent stenosis for 6 months after successful peripheral angioplasty and was well tolerated.