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Transplantation of tissues enclosed within a membrane device designed to protect the cells from immune rejection (immunoisolation) provides an opportunity to treat a variety of disease conditions. Successful implementation of immunoisolation has been hampered by the foreign-body reaction to biomaterials. We screened a variety of commercially available membranes for foreign-body reactions following implantation under the skin of rats. Histologic analysis revealed that neovascularization at the membrane-tissue interface occurred in several membranes that had pore sizes large enough to allow complete penetration by host cells (0.8-8 microns pore size). When the vascularization of the membrane-tissue interface of 5-microns-pore-size polytetrafluoroethylene (PTFE) membranes was compared to 0.02-microns-pore-size PTFE membranes, it was found that the larger pore membranes had 80-100-fold more vascular structures. The increased vascularization was observed even though the larger pore membrane was laminated to a smaller pore inner membrane to prevent cell entry into the prototype immunoisolation device. This significantly higher level of vascularization was maintained for 1 year in the subcutaneous site in rats.

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Adenosine has become the preferred treatment for common types of supraventricular tachycardia because it is extremely effective and rarely associated with with serious side effects. It has also been advocated as an intervention for diagnostic use to assess uncommon types of tachycardia. Evidence is shown in this report that adenosine was associated with dangerous worsening of arrhythmia in patients with atrial flutter. In two patients, adenosine precipitated acceleration of ventricular response, in one case necessitating emergent cardioversion. Both patients had atrial flutter with 2 to 1 atrioventricular block that evolved into 1 to 1 atrioventricular conduction. In three other patients, adenosine was associated with prolonged bradyasystole and hypotension. In each of the five patients, adenosine was given in a standard fashion (6 or 12 mg). In summary, adenosine should be recognized as a potentially dangerous intervention in patients with atrial flutter. If it is used for diagnostic purposes, resuscitative equipment should be readily available.

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Recanalization of completely occluded superficial femoral or popliteal arteries was attempted in 18 patients with use of an Argon laser-mediated thermal probe. The length of the occluded segments varied between 0.5 and 26.0 cm, but 67% of the occlusions were greater than 9 cm long. The initial success rate was 67%. Arterial perforation occurred in six patients but was not associated with major complications. To study the mechanism of the laser-mediated thermal probe, thermal recanalization was performed on 11 human arterial segments in vitro obtained after amputation, and mechanical recanalization was performed in vitro in 10 human peripheral arteries with use of a guide wire and catheter technique. An additional four arteries were studied with the laser probe as a non-heated mechanical device. Both the mechanical and thermal devices appear to follow a similar pathway through a complete obstruction. These studies suggest that the thermal probe burns through soft fibrous tissue but is mechanically deflected away from hard fibrocalcific plaque. The probe then advances along the plane between the intimal plaque and the media for a variable length before perforating through the adventitia. These observations suggest that the major mechanism of thermal probe recanalization may be a mechanical process. It appears that thermal probe devices do not inherently seek the true lumen of an occluded artery and that better guidance systems need to be developed.

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To understand whether quantitative measurement of minimal coronary luminal diameter is a better method than percent diameter narrowing for assessing the functional impairment of myocardial contractility produced by coronary artery stenoses, measurements were made from 37 stenotic segments in 27 patients with coronary artery disease and from corresponding segments in 10 subjects without coronary artery narrowing. An assessment of the reliability of the 2 types of measurements was made by correlating them with the physiologic parameters of both segmental wall motion and global ejection fraction response induced by atrial pacing. Digitally acquired coronary angiograms were used to facilitate quantitative analysis. Measurements by edge detection and videodensitometry correlated closely (r = 0.94). Percent diameter narrowing correlated moderately with the change in ejection fraction (r = -0.41) or with the change in segmental wall motion (r = -0.44). The measurement of minimal lumen diameter correlated with the change in global ejection fraction (r = 0.61) and did so even better with the change in segmental wall motion (r = 0.78, p less than 0.05). A minimal lumen diameter of less than or equal to 1.5 mm identified patients likely to have a functional impairment during atrial pacing as assessed by either global ejection fraction or segmental wall motion defects. We conclude that minimal coronary luminal diameter provides a better method than percent diameter narrowing calculations to measure the anatomic severity of coronary artery narrowing.

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During the 27-year period from 1956 to 1982, transvaginal parametrial needle biopsies were performed on 76 patients clinically suspected of harboring postirradiation recurrent cervical cancer without mucosal lesions suitable for biopsy under direct vision. Needle biopsies indicated cancer in 41 patients, resulting in 20 abdominal explorations. Eleven of these patients underwent total pelvic exenteration. Three patients survived longer than 5 years. Among 35 patients whose biopsies did not suggest cancer, eight proved to be false-negative as demonstrated by later progression of local and systemic disease. The remaining 27 patients in whom biopsies showed negative results were cured by radiation therapy. Bleeding, easily controlled by vaginal packing, occurred in one patient; in another, a pelvic abscess was drained 7 days after the biopsy. The authors conclude that when judiciously performed, transvaginal parametrial needle biopsy has a high diagnostic yield (89%) with minimal morbidity (2.6%). Its application during the careful observation of patients suspected to harbor recurrence may increase the operability rate and may offer selected patients a chance for cure by radical pelvic surgery.

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Among 1480 patients treated for cancers of the rectosigmoid over a 30-year period, 24 patients underwent total pelvic exenteration. These patients, 13 men and 11 women, had a median age of 64 years. Pathologic staging revealed 15 Dukes' B and nine Dukes' C lesions. For 17 patients, this operation was the only form of therapy. The operative mortality rate was 20.8%; however, the mortality rate has decreased to 13.3% during the past 20 years and to 9% in the past decade. Five complications occurred in the group surviving the procedure, resulting in a 26.3% morbidity rate. Three of the five complications occurred in patients who had previous radiation therapy or surgery. The overall 5-year survival rate was 41.6%. Those patients surviving the operation had 5- and 10-year survival rates of 52.6% and 31.5%, respectively. There were seven patients in whom the disease recurred at an average of 20.3 months after exenteration, and all died an average of 8 months later. The recurrence rate for patients with Dukes' B lesions was 27% compared with 57% for patients with Dukes' C lesions. The remaining 12 disease-free patients had a mean survival of 11 years. At present, four patients are alive and well 6 to 30 years after exenteration. The best predictor of morbidity was treatment before exenteration (p less than .005). Age older than 65 years and the presence of nodal metastases may contribute to increased mortality rates and recurrence, respectively, but these relationships were not statistically significant for the group. Total pelvic exenteration is advocated for selected primary, locally advanced, rectosigmoid lesions in good-risk patients; it can be achieved now with acceptable morbidity and mortality rates and a survival rate in excess of 40% at 5 years.

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Quantitative measurements of coronary stenoses were made from digital coronary angiograms in 19 patients before and after percutaneous transluminal coronary angioplasty (PTCA). Two methods of measurement were compared. Mean stenosis before PTCA was 67 +/- 10% by the edge detection method and 67 +/- 12% by videodensitometry (difference not significant). After PTCA, the mean stenosis was 32 +/- 14% by edge detection and 30 +/- 13% by videodensitometry (difference not significant). In addition, a new method was developed to rapidly calculate the absolute minimum luminal area and diameter by videodensitometry. The minimum luminal diameter before PTCA was 1.0 +/- 0.5 mm and after PTCA increased to 2.4 +/- 0.5 mm (p less than 0.001). The validity of the videodensitometric method was analyzed in a series of Lucite phantom studies, which suggested that when there is an irregular angiographic appearance, the densitometric method may be more accurate than standard edge detection methods. Digital acquisition of coronary angiograms provides a means for rapid application of quantitative analysis during coronary interventional procedures.

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Based on the results of experience accumulated in the past 30 years, exenterative pelvic surgery should be a part of the armamentarium of specially prepared oncologic surgeons. It is most frequently indicated for radiation failures in the treatment of carcinoma of the cervix, although it may be justified as primary treatment of selected cases of stage IV lesions without evidence of dissemination outside the pelvis. It is also justified for postirradiation radionecrosis causing sloughing and fistula, provided adequate relief cannot be offered by simple urinary and fecal diversion. For carcinoma of the rectum and pelvic colon, exenteration has a role in the advanced lesions that appear not to have become disseminated outside the pelvis but that involve contiguous viscera. Reoperation for recurrent carcinoma of the rectum is rarely successful, and this dreaded complication is best avoided by a well-planned and adequate standard first operation, or by the early recognition that a more extended operation is necessary. It is to be hoped that adjuvant radiation therapy, either preoperative or postoperative, or both, may be proved effective in preventing recurrence, especially for lesions below the peritoneal reflection, which is the most frequent site of recurrent disease. Finally, ultraradical pelvic surgery has reached its anatomical and pathologic limit. It only remains for the mortality and survival results to be further improved by continued refinements in the technicalities of the operation and in the judgment and selection of patients for it. Multimodal adjunctive therapy has an emerging role, as does selection of patients for functional preservation and reconstruction. The procedures should continue to be done in institutions where special studies are being conducted and where trained and experienced personnel are available with the necessary ancillary services.

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To determine the optimal time for recording left ventricular angiograms during atrial pacing stress tests, digital subtraction left ventriculograms were obtained using 12 ml of contrast material in 40 patients at rest and at peak pacing. Nineteen of the 40 patients had a third digital left ventriculogram performed between 5 and 10 seconds and 21 patients had a third digital left ventriculogram performed 30 seconds after pacing was stopped. Coronary angiography showed significant coronary artery disease (CAD) in 29 patients and no evidence of significant CAD in 11 patients. Ejection fraction (EF) increased or did not change at peak pacing in 10 of 11 patients without CAD. In the 29 patients with CAD, mean EF decreased an average of 10 percentage points (p less than 0.001) and fell 2 or more percentage points in 25 patients (86%) at peak pacing. These changes in EF were accompanied by the development of wall motion abnormalities, which occurred in segments of myocardium that were supplied by coronary arteries with angiographic CAD (more than 50% diameter narrowing). In contrast, the mean EF during the postpacing studies decreased only 2.2 percentage points (difference not significant) over rest values. Moreover, 15 of 29 patients (52%) with CAD had a decrease in EF of 2 or more percentage points. Therefore, the sensitivity of the atrial pacing stress test was diminished when the analysis was performed at 10 or 30 seconds after pacing. It is concluded that EF changes and wall motion abnormalities induced by atrial pacing are of short duration.(ABSTRACT TRUNCATED AT 250 WORDS)

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In an attempt to improve visualization of the position of the guidewire and dilatation balloon during coronary angioplasty, a method was developed called digital coronary roadmapping. With this method a digitally acquired coronary angiogram is interlaced with the live fluoroscopic image of the guidewire and balloon catheter. The digital coronary angiogram is superimposed at the same magnification and radiologic projection as the live fluoroscopic image onto the video monitor above the catheterization table. The digital roadmap image thus provides immediate feedback to the angiographer to assist in directing the guidewire into the appropriate coronary artery branch and to help in placement of the balloon so that it straddles the site of stenosis.

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To assess the ability to detect coronary artery narrowings from computer-acquired angiograms, a panel of 4 observers independently identified and measured focal coronary narrowings from digital subtraction angiograms and compared the results to those obtained from standard 35-mm cine film angiograms. Both cine and digital angiograms were obtained sequentially using selective intracoronary artery injection of standard amounts of iodinated contrast media. Digital images were obtained at 8 frames/s with a 512 X 512 X 8-bit pixel matrix. Modifications in the imaging chain for computer acquisition included a slower pulsed radiographic mode, a progressive scan camera, and initial storage of the images on an 80-megabyte digital hard disk. Postprocessing computer algorithms were used to enhance the unsubtracted digital images; these included single-frame, mask-mode subtraction, vessel boundary edge enhancement, and 4-fold pixel magnification. In 19 patient studies, 32 arteries were reduced more than 25% in diameter according to at least 1 of 4 observers on either the digital or cine film angiograms. There was no significant difference in the mean percent diameter narrowing for all the narrowings between the digital angiograms (53 +/- 31%) and the cineangiograms (52 +/- 31%). In addition, a 2-way analysis of variance yielded no significant difference between the amount of variability in the measurements between the cine film and the digital technique. This similar variability persisted when subsets of patients based on the degrees of stenosis were considered (e.g., only narrowings from 50 to 90% diameter reduction).(ABSTRACT TRUNCATED AT 250 WORDS)

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Severe damage to the pelvic viscera is a complication of irradiation therapy that, unfortunately, cannot always be avoided. Resulting rectal and rectocolonic strictures, rectovaginal fistulas, and shortening and stenosis of the vagina present very difficult problems that frequently require a colostomy for relief and may permanently impair sexual function. The authors present a new approach to correction of these unfortunate lesions based on the use of proximal nonirradiated colon which serves as a vascular pedicle graft to correct the defect without a complicated and massive resection. Twenty-two such operations have been done with 19 satisfactory to excellent results and two total failures (one death from small bowel complications). All patterns and combinations of irradiation injury have been found amenable to this technique of repair. These have included both web and linear strictures with and without fistulas. In half of the patients, it was possible to make use of normal colon bypassed by a prior colostomy. Normal nonirradiated colon with good blood supply will heal satisfactorily to irradiated colon or rectum, thus making excision of all the irradiated tissue unnecessary. The results of this surgical approach have thus far been gratifying and warrant further trials for these distressing injuries.

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Left ventricular ejection fraction (LVEF) was calculated from 25 first-pass digital subtraction angiograms using a densitometric analysis. Digital subtraction angiograms are obtained in a computerized format; therefore, they can be readily analyzed with computer software to measure the density of the iodine signal within the image. The video signals from the image intensifier were logarithmically amplified so that there was a linear correlation between the video signal intensity and the depth of the iodine contrast material represented by that video signal. LVEF was also calculated by the area-length method from the same digital subtraction angiograms. There was close correlation between these two techniques (r = 0.94, standard error of the estimate = 5.04%). The videodensitometric EF technique is simple to perform, it correlates well with the standard area-length method, and is not dependent on geometric assumptions of LV geometry.

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Left ventriculograms were obtained with the use of 10 ml of contrast media by passing fluoroscopic video images through a video image processor. The low concentration of dye in the left ventricle was enhanced by the technique of mask mode subtraction, and the images were postprocessed to increase visibility by manipulation of the gray scale and contrast levels. These digital subtraction angiograms were compared to standard cineangiograms by means of 40 ml of contrast media. Of 30 patients studied, six (20%) had runs of ventricular tachycardia during the cineangiogram and had to be excluded. In the remaining 24 patients, there was a good correlation between the two techniques for left ventricular end-diastolic volume (r = 0.77, end-systolic volume (r = 0.95), and ejection fraction (r = 0.97). Spatial resolution in the digital studies was adequate to appreciate wall motion abnormalities that were visualized on the cineangiograms. Left ventricular end-diastolic pressure (LVEDP) did not change after the 10 ml injection, but the mean LVEDP rose 6.0 mm Hg after the 40 ml cineangiograms (p less than 0.01). Digital subtraction angiography can be used to obtain left ventriculograms with one-fourth the amount of contrast media and one-fourth the x-ray exposure compared to standard cineangiograms. This technology will permit multiple left ventriculograms to be obtained which, in turn, will allow intervention studies to be performed in the catheterization laboratory.

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Using digital subtraction angiography, left ventriculograms were obtained with 10 ml of iodinated contrast material in 21 patients both at rest and during atrial pacing. In 15 patients with significant coronary artery lesions (CAD) (greater than 50% diameter narrowing in at least 1 major artery), ejection fraction decreased during atrial pacing from a mean of 62 +/- 14% to 51 +/- 15% (p less than 0.001). In 14 (93%) of 15 patients, ejection fraction decreased or was unchanged during pacing. In 6 patients with chest pain but normal coronary arteries, ejection fraction increased from a mean of 66 +/- 9% at rest to 72 +/- 6% during atrial pacing (p less than 0.01). Ejection fraction increased by greater than or equal to 5% during pacing in 5 of 6 patients with normal coronary arteries. Patients with CAD also had an abnormal response in end-systolic volume during atrial pacing (50 +/- 31 ml at rest versus 47 +/- 24 ml during pacing) compared with patients with normal coronary arteries (46 +/- 16 ml at rest versus 26 +/- 9 ml during pacing; p less than 0.01). The digital ventriculograms demonstrated new or increased wall motion abnormalities during atrial pacing in 4 of 5 patients with CAD who had wall motion abnormalities at rest and in 8 of 10 patients with CAD who had normal wall motion at rest. Moreover, these wall motion abnormalities occurred in myocardial wall segments that were supplied by coronary arteries with significant lesions. Thus, because digital subtraction angiography allows multiple left ventriculograms to be obtained during routine cardiac catheterization, intervention studies such as atrial pacing can be used to obtain a functional assessment of the severity of coronary arterial lesions.

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