Laser-assisted thermal angioplasty in human peripheral artery occlusions: mechanism of recanalization.

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.

Measurement of left ventricular ejection fraction by videodensitometric analysis of digital subtraction angiograms.

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.

Correlation of minimum coronary lumen diameter with left ventricular functional impairment induced by atrial pacing.

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.

Detection and quantitation of coronary artery stenoses from digital subtraction angiograms compared with 35-millimeter film cineangiograms.

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)

Digital coronary roadmapping as an aid for performing coronary angioplasty.

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.

Determination of the optimal timing for performing digital ventriculography during atrial pacing stress tests in coronary heart disease.

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)

Videodensitometric determination of minimum coronary artery luminal diameter before and after angioplasty.

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.

Digital angiography in assessment of ventricular function and wall motion during pacing in patients with coronary artery disease.

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.

Exenterative surgery for locally advanced rectosigmoid cancers. Is it worthwhile?

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.

Prognostic effect of tobacco and alcohol use in patients with oral tongue cancer.

A retrospective case analysis shows that patients with oral tongue cancer who have chronically used tobacco and alcohol have an increased incidence of death due to tumor, due to a second primary cancer, and due to intercurrent disease when compared with patients with oral tongue cancer who have never used tobacco or alcohol. This difference is not explained by a difference in tumor staging, patients' ages, or type of treatment received.

Prognostic significance of surgical perforation of the rectum during abdominoperineal resection for rectal carcinoma.

Two hundred fifty patients were followed up after resection for carcinoma of the rectum. Sixty-four (25.6 percent) had a surgical perforation in the resected rectum. Perforation did not affect the long term outcome in patients with Dukes' A or D tumors, but in patients with Dukes' B and C cancers the surgical defect was associated with an increased incidence of recurrent tumor (57 versus 34 percent) and a decreased 5 year survival rate (31 versus 46 percent). The local recurrence rate was significantly higher in patients with Dukes' B rectal cancer who had an iatrogenic perforation (25.9 percent) than in those without a perforation (8.1 percent). This increased local recurrence rate was as high as the local recurrence rate in patients with Dukes' C cancers (23 percent) with or without a perforation. Patients with Dukes' B or C cancers who had incomplete resection had survival patterns similar to those in patients with Dukes' D cancers. Failure to remove all gross tumor and failure to avoid rectal perforation during abdominoperineal resection increases the risk of recurrence and decreases the chance of long-term survival.

Reconstructive surgery for the complications of pelvic irradiation.

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.

Determination of the fatty-acid composition of soybean oil by high-pressure liquid chromatography.

A method for determining the fatty-acid composition of soybean oil by using high-pressure liquid chromatography (HPLC) is discussed and compared with the determination using gas chromatography. The oil is saponified and an aliquot is treated directly to form the p-bromophenacyl esters of the fatty acids, which are separated by gradient-elution HPLC. It is shown that glycerol does not interfere with the esterification, thus obviating the solvent extraction previously used to isolate fatty acids from biological samples.

The current role of ultraradical surgery in the treatment of pelvic cancer.

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.

The instrument function of a wide angle Michelson interferometer spectrometer.

The instrument function of a wide angle Michelson interferometer spectrometer is derived in terms of known or easily measured functions using a novel method of computing the phase difference between the two beams. The interferometer essentially achieves immersion with solid materials and has the advantages of a larger field of view and fewer reflecting interfaces. A set of instrument functions is plotted in which either the field of view or the wavelength, with the other held fixed, may be interpreted as the parameter. The allowable field of view is found to increase linearly with the index of refraction of the cube material. A simple working model yielded both white light and mercury green light fringes.