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Biomedical subjects

W S Grundfest

Publications and source records attributed to W S Grundfest.

At least 19 recordsLinked to original sources
PubMed1996

Safety evaluation of laparoscopically applied clips.

We have evaluated in vitro, the security of laparoscopically applied clips, through two commercially available clip appliers: the Endo Clip II (US Surgical) and the Ligaclip (Ethicon). The clip performance was tested with respect to dislodgment and leakage. Dislodgment was attempted both transversely and at 45 degrees with respect to the main axis of the tubular structures tested. The mean maximum force (N = 24) necessary to dislodge a clip applied to silicone tubing (2.1, 2.4, 3.2 mm o.d.) and porcine vascular tissue was measured. The maximum force needed to transversely dislodge a clip applied to silicone tubing, ranged from 262 +/- 9 g (2.1 mm) to 315 +/- 11 g (3.2 mm) for the Endo Clip II applier, while the values for the Ligaclip were 220 +/- 28 g (2.1 mm) and 273 +/- 11 g (3.2 mm), respectively. To achieve dislodgment at 45 degrees pull, corresponding forces of 294 +/- 8 g (2.1 mm) and 369 +/- 14 g (3.2 mm) for the Endo Clip II, and 254 +/- 14 g (2.1 mm) and 297 +/- 13 g (3.2 mm) for the Ligaclip (N = 24) were required. Transverse dislodgment forces, for clips applied to tissue, were 556 +/- 146 g for the Endo Clip II and 356 +/- 170 for the Ligaclip (N = 6). Leakage tests were also performed under pulsatile blood circulation at mean pressure of approximately 800 mm Hg. No tested clips applied to either silicone tubing or tissue allowed for any blood leakage. The dislodgment test showed that the Endo Clip II exhibits superior performance compared to the Ligaclip, based on the fact that it requires more force for transverse and semiaxial dislodgment. In the leakage test, both clip appliers performed equivalently.

Animals↗
PubMed1995

Spectro-temporal studies of Xe-Cl excimer laser-induced arterial wall fluorescence.

We report on spectro-temporal fluorescence studies of cadaver femoral arterial walls at different stages in the progression of atherosclerosis. After excitation with a Xe-Cl excimer pulse, the time course of the fluorescence spectrum was recorded over time, and time-resolved multispectral analysis was performed. Then, under the assumption of linearity, we derived a linear spectro-temporal kernel (a weighting function) which describes the temporal behavior of the fluorescence process independently of the pulse width of the photoexcitation. The data analysis revealed both static and dynamic fluorescence characteristics which exhibited a good correlation with histological findings.

Arteriosclerosis↗
PubMed1994

Photodynamic therapy for the treatment of squamous cell carcinoma using benzoporphyrin derivative.

BACKGROUND: Photodynamic therapy (PDT) involves laser light excitation of a tumor-localizing photosensitizer to destroy neoplasms. Benzoporphyrin derivative (BPD) is a new photosensitizer with several favorable characteristics. OBJECTIVE: Studies were designed to: 1) assess the efficacy of BPD-mediated PDT in treating in vivo squamous cell carcinomas (SCC); 2) obtain dosimetry data for BPD and laser parameters; and 3) establish clinical and histologic correlates of BPD-induced tumor regression. METHODS: Human SCC was implanted into nude mice. One group received BPD followed by laser light of 150 J/cm2 from an argon-pumped dye laser at 690 nm. Three control groups included laser energy alone, BPD alone, and no treatment. RESULTS: At day 21 posttreatment only PDT-treated tumors showed a statistically significant decrease in tumor volume and complete cure rate. Clinical resolution (scar) correlated perfectly with histologic resolution (scar). CONCLUSION: Human SCC in a nude mouse model responds to BPD-mediated PDT.

Anaplasia↗
PubMed1993

Effect of varying laser parameters on pulsed Ho:YAG ablation of bovine knee joint tissues.

We investigated the effect of varying laser parameters on ablation of fresh bovine knee joint tissues (fibrocartilage, hyaline cartilage, and bone) with a free-running Ho:YAG laser. Ablation rate was measured in saline for each tissue type as a function of laser fluence (160-950 J/cm2), pulse width (150-450 microseconds, full width at half maximum), and fiber core diameter (400 and 600 microns). A weight that was attached to the fiber end was used to exert a constant pressure of 40 g/mm2 to the tissue underneath to ensure a constant contact between the fiber tip and the tissue throughout the ablation process. All tissues could be efficiently ablated, and the ablation rate increased linearly with the fluence. Change in laser pulse width and fiber core diameter resulted in minor variations in the ablation rate for fibro- and hyaline cartilage. On the other hand, use of longer pulses and/or the larger fiber significantly accelerated bone ablation. Histology analysis revealed that zones of thermal damage in Ho:YAG irradiated bovine knee joint tissues differed by tissue types and ranged between 100 and 400 microns, but were independent of fluence, pulse width, and fiber size within the range tested.

Animals↗
PubMed1992

Endoscopy of the lacrimal outflow system.

Management of obstructions in the lacrimal drainage system would be greatly aided by improvements in the ability to visualize the blockages. We describe a new method of observation using miniature fiberoptics to view the entire lacrimal excretory system. We employed flexible endoscopes of fiberoptic bundles with outside diameters of from 0.5 to 0.7 mm. These endoscopes were inserted through the puncta and canaliculi. Sixteen patients were examined. A range of pathologic conditions were found, including slightly stenosed passages and severely destroyed canalicular mucosal lining. Our results indicate that this technique is feasible and useful in the diagnosis of lacrimal excretory disease.

Endoscopes↗
PubMed1992

Falloposcopic classification and treatment of fallopian tube lumen disease.

OBJECTIVE: To devise a diagnostic classification and scoring system for tubal lumen disease based on falloposcopy and to evaluate it against tuboplasty procedures and pregnancy outcomes. DESIGN: Prospective study approved by the hospital Institutional Review Board. SETTING: Academic tertiary infertility center. PATIENTS: Seventy-five women with hysterosalpingographic and laparoscopic evidence of endotubal disease had 112 tubes available for falloposcopic evaluation. INTERVENTION: Diagnostic and operative falloposcopy was performed, when indicated, using aquadissection, flexible wire cannulation, or direct balloon tuboplasty. RESULTS: The endotubal lumens were considered to be falloposcopically normal in 52 tubes (46%), to contain mild to moderate disease in 33 (29%), and severe to obstructive disease in 27 (25%) cases. Within a year of the procedure, 6 of the 28 women (21%) in whom at least 1 tube was normal conceived, in 2 of 22 (9%) with mild to moderate disease, and in 0 of 16 (0%) with severe endotubal disease. CONCLUSIONS: Falloposcopy provides a visual means of scoring endotubal disease and may be intrinsically therapeutic for dislodging intraluminal debris and breaking down filmy adhesions in normal or minimally diseased tubes. The presence of severe disease remains resistant to the use of current endotuboplasty treatments as reflected by poor pregnancy outcome, and such women should be provided the option of microsurgical tubal repair or in vitro fertilization and embryo transfer procedures.

Adult↗
PubMed1992

Laparoscopic choledochoscopy: an effective approach to the common duct.

With increasing acceptance of routine cholangiography during laparoscopic cholecystectomy (for confirmation of anatomy) there has been increased identification of common duct calculi. A technique of laparoscopic transcystic common duct stone extraction is described and early clinical results are presented. Successful stone extraction was accomplished in 39 out of 41 consecutive attempts by one surgical team. Two cases required choledochotomy. There were four complications including hyperamylasemia (2), minor wound infection (1), and incidental pneumothorax (1). Recommendations regarding safety and indications are presented. Initial evaluation suggests laparoscopic transcystic stone extraction is safe and effective.

Adolescent↗
PubMed1992

Experimental endoscopic subcutaneous surgery.

Endoscopic techniques have found increasing applications in general surgery. In this article, an attempt has been made to utilize endoscopy via a subcutaneous approach in an experimental pig model for dissection of fat, muscle, and fascia.

Adipose Tissue↗
PubMed1992

Percutaneous endoscopic implantation of Automatic Implantable Cardioverter/Defibrillator (AICD): an animal study of a new nonthoracotomy technique.

The Automatic Implantable Cardioverter/Defibrillator (AICD) prevents death due to malignant ventricular arrhythmias but requires thoracotomy for the implantation of the preferred two-patch lead system. The purpose of this study was to develop and test a new percutaneous endoscopic method of the AICD lead implantation without the need for open chest surgery. A high resolution video endoscopy system and currently available endoscopic instrumentation were used to develop pleural-pericardial dissection technique in 7 pigs and to endoscopically implant custom-made AICD patches in 20 pigs. An examining 10 mm rigid endoscope inserted in the 6th intercostal space in the anterior axillary line provided direct visual control for endoscopic dissection of the parietal pleura from the pericardium, delivery, and implantation of the AICD patches. This was successfully carried out through two trocars (10 and 11 mm) inserted into the pleural-pericardial space via the subxyphoid approach in 18 of 20 pigs. Effective patch positioning was confirmed by attaining a defibrillation threshold of 20J or less in 13 pigs. Of those, three required lead polarity reversal, and three others required lead repositioning to lower defibrillation thresholds to 20J or less. In three pigs, defibrillation thresholds of 30J or higher were required. Defibrillation was unsuccessful in two pigs due to patch malfunction. The authors conclude that percutaneous endoscopy is a feasible method of AICD lead implantation.

Animals↗
PubMed1992

Tissue ablation through water with erbium:YAG lasers.

We report the dynamics of vapor cavities generated by 200 microseconds long Er:YAG laser pulses under water and in gelatin. Acoustic transients were detected at the beginning of the laser pulse and when the cavity collapsed. Cavity expansion and collapse, and the associated acoustic transients are possible ablation mechanisms with the Er:YAG laser. Shortening of the pulse duration is suggested to minimize long range under water tissue damages.

Acoustics↗
PubMed1991

Excimer laser ablation of fibrocartilage: an in vitro and in vivo study.

To date, lasers have found only limited applications in orthopedics. We employed a 308 nm XeCl excimer laser for ablation of fibrocartilage, in order to investigate the feasibility of excimer laser assisted meniscectomy. Experiments were conducted both in vitro and in vivo. For the in vitro study, human menisci, obtained during surgery and autopsy, were irradiated via a 600 microns core fiber at radiant exposures ranging between 20 mj/mm2 and 80 mj/mm2, at 20 Hz. Ablation rate measurements and histological analysis of the samples were performed. The ablation rates were found to range from 3 microns/pulse to 100 microns/pulse depending on the radiant exposure and/or the applied pressure on the fiber delivery system. Thermographic analysis was also performed during pulsed excimer as well as CW Nd:Yag and CW CO2 laser irradiation. Temperatures were lower for excimer laser (Tmax less than 65 degrees) than CW ND: Yag (Tmax less than 210 degrees) or CW CO2 (Tmax less than 202 degrees) laser. For the in vitro study, medial meniscectomy was performed in 15 rabbits with the excimer laser and a CW Nd:Yag laser in the right and left knee respectively. Excimer laser irradiation was performed at 70 mj/mm2. Nd:Yag irradiation was performed via a 600 microns core fiber at power outputs between 20 to 40 W for 10 and 20 seconds duration. The healing response to injury was investigated by histological analysis of the menisci after 1 day, 1, 2, 4, and 8 weeks following the laser procedure. Excimer laser treated menisci showed less inflammatory reaction and noticeable repair with minimal inflammatory response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Falloposcopic observations of endotubal isthmic plugs as a cause of reversible obstruction and their histological characterization.

Eighty falloposcopies were performed in fallopian tubes of women with suspected tubal disease. In three falloposcopies (4%), isthmic plugs were observed occluding the entire isthmic lumen. In all cases these plugs were mobilized by falloposcopic-directed, selected tubal cannulation and aquadissection techniques. Restoration of tubal patency, verified by concurrent chromopertubation under laparoscopic monitoring was achieved in all cases. On one occasion, the isthmic plug was mobilized and identified on the fimbria, and tubal patency was confirmed. When this plug was retrieved and examined histologically, it was found to consist of a cast of debris containing aggregates of histiocyticlike cells of endometrial stromal or mesothelial origin. The genesis of these plugs is unknown. In another subgroup, white to yellow mucus like fragments were observed within the intramural and isthmic lumen during a further 8 of 80 falloposcopies (10%). Whether these mucus like fragments are of physiological or pathophysiological significance remains to be determined. Objective demonstration that isthmic plugs can cause reversible proximal tubal obstruction (PTO) has been achieved using falloposcopy. Falloposcopy offers the diagnostician the ability to objectively classify the cause of PTO. A useful falloposcopic classification and scoring system of tubal lumen lesions has been utilized and is described.

Adult↗
PubMed1991

Falloposcopic identification of a fimbrio-ovarian mucus connection as a possible mechanism for tubal oocyte capture.

Falloposcopy combined with laparoscopy was performed in 11 women during the late follicular phase of spontaneous menstrual cycles, and a preovular follicle was confirmed to be present in each case. The fimbrial end of the tube and the ipsilateral ovary containing the preovular follicle were suspended in a fluid environment of 200 ml of lactated Ringer's solution which acted as a support medium for visualization of tubal mucus and facilitated the endoscopy procedure. As the falloposcope was passed through the fimbrial opening, it was observed to carry clear, elastic and filamentous strands of mucus material from within the distal tubal lumen in 4 of 11 procedures. As these mucus strands were carried on the tip of the falloposcope to touch the surface of the ovary containing the preovular follicle, they attached, on contact, in all cases. The fimbrio-ovarian mucus bridge created was quite strong and could be stretched for up to 7 mm before it detached from the ovarian surface. The mucus attachment appeared to be equally secure over the preovular follicle and adjacent ovarian surfaces. These fimbrio-ovarian mucus connections, which have a high affinity for ovarian surface attachment about the time of ovulation, may play an important role in securing tubal oocyte capture in humans.

Broad Ligament↗
PubMed1991

XeCl excimer laser-induced fluorescence for selective ablation of atheromatous tissue.

In order to develop a reliable laser-induced fluorescence (LIF) guided laser angioplasty system, real time, pulse-by-pulse fluorescence spectra were recorded and the same fiberoptic was used for both detection of the fluorescence and for atheromatous tissue ablation. A 308 nm XeCl excimer laser served as the laser source for both the induction of fluorescence and the ablation. The fluorescence signal was induced at high laser energies during ablation without any serious change in the fluorescence pattern. A new characteristic fluorescence peak at 540 nm for atheromatous tissue was observed after treatment with chlortetracycline hydrochloride (CTC). This allowed the development of an algorithm and a subsequent index to discriminate the atheromatous tissue from the normal tissue. During atheromatous tissue ablation, this index changed as normal tissue was approached, thereby avoiding vessel perforation. Our results suggest that monitoring of this index through the catheter delivering the laser energy enhances selective ablation while simultaneously reducing the risk of vessel perforation.

Arteriosclerosis↗
PubMed1990

Percutaneous excimer laser coronary angioplasty.

To determine the efficacy of percutaneous excimer laser coronary angioplasty as an adjunct or alternative to conventional balloon angioplasty, 55 patients were studied in a multicenter trial. These patients underwent the procedure using a modification of conventional balloon angioplasty technique. A first-generation, 1.6-mm diameter catheter constructed of 12 individual silica fibers concentrically arranged around a guidewire lumen was used. Catheter tip energy density varied from 35 to 50 mJ/mm2. The mean number of pulses delivered at 20 Hz was 1,272 +/- 1,345. Acute success was defined as a greater than or equal to 20% increase in stenotic diameter and a lumen of greater than or equal to 1 mm in diameter after laser treatment. Acute success was achieved in 46 of 55 (84%) patients. Adjunctive balloon angioplasty was performed on 41 patients (75%). The percent diameter stenosis as determined by quantitative angiography decreased from a baseline of 83 +/- 14 to 49 +/- 11% after laser treatment and to 38 +/- 12% in patients undergoing adjunctive balloon angioplasty. The mean minimal stenotic diameter increased from a baseline of 0.5 +/- 0.4 to 1.6 +/- 0.5 mm after laser treatment and to 2.1 +/- 0.5 mm after balloon angioplasty. There were no deaths and no vascular perforations. One patient (1.8%) required emergency coronary bypass surgery. These data suggest that excimer laser energy delivered percutaneously by specially constructed catheters can safely ablate atheroma and reduce coronary stenoses.

Angioplasty, Laser↗
PubMed1990

Angioscopy for intraoperative management of thromboembolectomy.

Our experience with angioscopy suggests that direct visualization of the arterial lumen during thromboembolectomy procedures would provide a more reliable method of assessing luminal morphologic characteristics than angiography alone. We inspected 32 grafts (seven aortobifemoral, 18 infrainguinal bypass, and seven dialysis access fistula grafts) in 32 patients. Thirty-one patients had thrombotic events and one patient had an acute embolus. Angioscopy following standard catheter thrombectomy revealed significant amounts of retained thrombus or neointima in all thrombectomies. Angioscopic information from 18 patients with an infrainguinal bypass graft led to graft revision in six cases and placement of a new graft in 10 cases. One graft limb was replaced in seven aortobifemoral grafts, and multiple repeated thrombectomies were employed to extract debris in the remaining six cases. Repeated graft thrombectomy was also beneficial in dialysis access fistulas. Angioscopy allowed us to omit the completion angiogram and led to an improved technical result. We conclude that angioscopy is useful during thromboembolectomy procedures.

Aged↗