In vitro evaluation of ablation parameters of normal and fibrous aorta using smooth excimer laser coronary angioplasty

A modified exeimer laser energy delivery system was used to irradiate 100 segments of normal and fibrous aorta in vitro. The laser beam was scanned into 8 fiber bundles consisting of 50 fibers each resulting in a reduction of the applied pulse energy. The total repetition rate was increased to 150 Hz in order to keep the repetition rate per fiber bundle close to 20 Hz and to minimize thermal injury. The results demonstrate that effective ablation (etch rate per 8 pulses > 2.0 μm) occurred at an energy fluency of 50 mJ/mm² in both normal and fibrous aorta. Tissue damage (carbonization, tissue separation, fissures, cracks, and vacuolization) was in a range of 100 ± 28 to 152 ± 30 μm for normal aorta and in a range of 57 ± 35 to 110 ± 39 μm for fibrous aorta. We conclude that effective ablation of normal and fibrous human aorta can be achieved by the application of smooth excimer laser coronary angioplasty. This improvement of excimer laser technology may result in a reduction of shock wave- and cavitation-induced damage leading to a reduction of tissue injury. However, this awaits further in vitro and in vivo confirmation. © 1993 Wiley-Liss, Inc.     

The effects of radiofrequency catheter ablation on the metabolic enzymes and Ca++-ATPase of myocytes

Summary Using histochemical technique, the effects of radiofrequency catheter ablation (RFCA) on the activities of LDH, SDH, CCO, and Ca⁺⁺-ATPase of guinea-pig ventricular myocytes were examined. The histological changes were observed for comparison. Radiofrequency energy (500 kHz) delivered was 20 WX 10 s. The results were as follows: RFCA resulted in significant impairments in all the four kinds of enzymes but without statistical differences in the areas involved in this energy level. No statistically significant difference was found between the ranges of enzymatic damages and areas of pathological lesions. These findings showed a consistency in areas of the histological and histochemical lesions resulted from RFCA.     

Automated lumen definition from 30 MHz intravascular ultrasound images

One prerequisite for standard clinical use of intravascular ultrasound imaging is rapid evaluation of the data. The main quantities to be extracted from the data are the size and the shape of the lumen. Until now, no accurate, robust and reproducible method to obtain the lumen boundaries from intravascular ultrasound images has been described. In this study, 21 different (semi-)automated binary-segmentation methods for determining the lumen are compared with manual segmentation to find an alternative for the laborious and subjective procedure of manual editing. After a preprocessing step in which the catheter area is filled with lumen-like grey values, all approaches consist of two steps: (i) smoothing the images with different filtering methods and (ii) extracting the lumen by an object definition method. The combination of different filtering methods and object definition methods results in a total of 21 methods and 80 experiments. The results are compared with a reference image, obtained from manual editing, by use of four different quality parameters—two based on squared distances and two based on Mahalanobis distances. The evaluation has been carried out on 15 images, of which seven are obtained before balloon dilation and eight after balloon dilation. While for the post-dilation images no definite conclusions can be drawn, an automated contour model applied to images smoothed with a large kernel appears to be a good alternative to manual contouring. For pre-dilation images a fully automated active contour model, initialized by thresholding, preceded by filtering with a small-scale median filter is the best alternative for manual delineation. The results of this method are even better than manual segmentation, i.e. they are consistently closer to the reference image than the average distance of all individual manual segmentations.     

导管射频消融治疗房室结折返性心动过速前后心率变异的改变

对２０例房室结折返性心动过速患者在射频消融前后进行心率变异频域和时域分析，以了解射频消融对心脏自主神经系统的影响。结果显示，心率变异的极低频段（ＵＬＦＰ）、低频段（ＬＦＰ）、高频段（ＨＦＰ）及总能谱（ＴＦＰ）均较射频消融前降低（Ｐ〈０．０５）。提示射频消融对心脏交感神经、融交感神经均有损害，而以副交感神经损害为主。     

Radiofrequency Current Ablation of Porcine Right Atrium: Increased Lesion Size with Bipolar Two Catheter Technique Compared to Unipolar Application In Vitro and In Vivo

Interruption of atrial flutter and fibrillation by RF catheter ablation may be favored by large, elongated lesions. We administered RF current in unipolar and bipolar mode in porcine right atrium. Bipolar ablation was performed between the tip electrodes of two serially coupled catheters. With 4-mm tip electrodes in vitro, lesion length increased from a mean (SD) of 7.9 (1.2) mm at 3 mm-interelectrode distance (IED) to 13.3 (3.3) mm at 9-mm IED, but decreased at 12-mm IED due to nonconfluent lesions (P < 0.0001), With 4 mm distal electrodes and 8 mm IED, bipolar lesions were 65% longer than corresponding unipolar ablations. Switching to bipolar mode increased the lesion length more than increasing electrode tip length to 6 mm in unipolar mode. Power and temperature controlled ablation created equally sized lesions. Twelve anesthetized pigs were randomized to unipolar or two catheter bipolar temperature controlled ablation of the right atrial free wall. Bipolar ablation created confluent lesions with endocardial length × width of 13.5 (5.8) × 7.3 (3.7) mm, unipolar ablation 6.4 (2.8) × 4.6 (1.4) mm (P < 0.001 when comparing length and P = 0.013 for lesion width). The atrial lesions in both groups were transmural and extended into hilar lung lesions with maximal depth of 3.0 (1.1) and 2.6 (1.0) mm, respectively (P = 0.44). Five bipolarly and four unipolarly ablated pigs developed right diaphragmal paresis. We conclude that bipolar ablation may be preferable in situations where large, elongated lesions are favorable. The two catheter technique is feasible in porcine right atrium. Both bipolar and unipolar ablation of the porcine right atrial free wall may frequently be complicated by injury to the phrenic nerve and adjacent lung tissue.     

Two-step endoscopic resection of gastric leiomyomas

Summary Our two-step technique for endoscopic treatment of gastric leiomyomas is illustrated. From January 1979 to June 1991, nine symptomatic patients with sessile leiomyomas of the stomach were treated at the Endoscopy Division of Istituto Nazionale Tumori, Milan.The diagnosis was achieved by means of endoscopic observation of the lesion and, when possible, by ultrasound endoscopy.This new technique consists of first removing superficial portion of the tumor by electrosurgical snare. Second, a cleavage plane is found within the proper muscle layer; the tumor is enucleated as much as possible by tightening the snare around it and creating a pseudo-stalk. No major complication occurred nor were any recurrences observed at 21.8 months in the 7/9 patients treated by endoscopy alone. Endoscopic therapy was performed on an outpatient basis and only large lesions required short hospitalization.     

Imaging studies of the cadaver hand using transmission ultrasound

Ultrasonic transmission imaging has already demonstrated potential for evaluating structures in the hand. In this study, a cadaver hand was imaged using a transmission scanner with improved imaging capability. The hand was then frozen and serially sectioned and comparisons were made between the sectional anatomy and the corresponding image. Bone (in silhouette), muscle, cartilage, and tendon were visualized with high resolution.     

24例阴道肿瘤的B超诊断

目的 通过对24例阴道肿瘤患者的B超声像图分析，总结B超诊断阴道肿瘤的方法。方法 收集24例1995～2002年，我院门诊及住院患者的病史资料及声像图，结合病理结果分析声像图特征，并与病理加以对照。结果 24例患者声像图表现为囊性、实质性、囊实性肿瘤。结论 通过对声像图的分析，探讨了B超诊断阴道肿瘤的可行性、声像图特征及该方法的局限性。     

超声观察银屑病中医分型的血管变化研究

目的　探讨银屑病中医分型皮损处与正常皮肤处血管血流的变化情况。方法　将 3 0例寻常型斑片状银屑病按中医辨证分型 ,超声观察患者正常皮肤处及皮损处浅层动脉血管、静脉血管血流情况。结果　“血热型”皮损处及正常皮肤处动脉血管增大、扩张、血流加快 ;“血瘀型”及“血燥型”未发现异常。结论　银屑病动脉血管及静脉血管增大、扩张、血流加快与中医分型“血热型”密切相关 ,这些将有助于临床根据中医分型进行辨证施治     

Drug Delivery by Phonophoresis

Phonophoresis is defined as the migration of drug molecules, contained in a contact agent, through the skin under the influence of ultrasound. Several drugs have been introduced into the body by this technique. The design of a phonophoretic drug delivery system is in developmental stages in various research laboratories. Parameters affecting the delivery of drugs by this technique and devices available for drug delivery purposes are discussed in this review.