Search PubMed⌕ Search

Biomedical subjects

R T Gregory

Publications and source records attributed to R T Gregory.

At least 37 records · Page 2Linked to original sources
PubMed1991

Spontaneous carotid dissection: duplex scanning in diagnosis and management.

The clinical, duplex, and angiographic findings in six patients with seven spontaneous extracranial carotid artery dissections are reported. Four dissections resulted in internal carotid artery occlusion. These patients complained of ipsilateral headache followed by contralateral hemiplegia. The other three dissections involved the common carotid artery and resulted in dual (one true and one false) lumens. Two of these dissections were asymptomatic. All dissections were treated nonoperatively with anticoagulant therapy. Neurologic deficits improved or disappeared in all symptomatic patients. On follow-up studies, one of the four internal carotid occlusions completely resolved with normalization of the duplex examination. All three dual lumen dissections remained patent on serial studies. Diagnostic duplex characteristics, both conclusive and supportive, of carotid dissections are described. Duplex scanning is shown to be accurate in diagnosing and ideally suited for serially following spontaneous carotid dissections.

Adult↗
PubMed1991

Experience with laser-assisted balloon angioplasty and a rotary angioplasty instrument: lessons learned.

Favorable early results with mechanical angioplasty devices and laser-assisted balloon angioplasty have resulted in aggressive marketing and a rapid increase in the use of these devices for the treatment of femoropopliteal occlusive disease. Recent reports, however, have questioned the durability of these less invasive procedures. Since 1986 we have been involved in the clinical investigation of the Kensey dynamic angioplasty instrument and laser-assisted balloon angioplasty. One hundred two balloon angioplasty procedures assisted by the Nd:YAG laser (n = 56) and the Kensey dynamic angioplasty instrument (n = 46) were performed for the treatment of femoropopliteal occlusive lesions. Both Kensey dynamic angioplasty instrument and laser-assisted balloon angioplasty groups were similar with regard to age, operative indication, preoperative ankle-brachial index, lesion length, and distal runoff. Mean follow-up was 19 months in the Kensey dynamic angioplasty instrument group and 15 months in the laser-assisted balloon angioplasty group. Technically successful recanalization was achieved in 67% of Kensey dynamic angioplasty instrument-assisted balloon angioplasty procedures and 82% of laser-assisted balloon angioplasty procedures. Early hemodynamic and clinical improvement was obtained in 59% of Kensey dynamic angioplasty instrument-assisted balloon angioplasty procedures and 57% of laser-assisted balloon angioplasty procedures. Two-year clinical success by life-table analysis was 37% in the Kensey dynamic angioplasty instrument group and 19% in the laser-assisted balloon angioplasty group. The level of subsequent surgical revascularization was not altered in any patient by Kensey dynamic angioplasty instrument-assisted balloon angioplasty or laser-assisted balloon angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Initial results and subsequent outcome of laser thermal-assisted balloon angioplasty of 56 consecutive femoropopliteal lesions.

Laser thermal-assisted balloon angioplasty (LABA) was prospectively applied in the treatment of 56 atherosclerotic femoropopliteal occlusive lesions in 51 consecutive patients. All procedures were performed in the operating room using a neodynium:yttrium-aluminum-garnet (Nd:YAG) laser source, and patients were evaluated for immediate and long-term hemodynamic and clinical improvement. Technically successful recanalization was achieved in 82% of cases, with 57% of all patients (32 of 56) obtaining early hemodynamic and clinical improvement. Long-term clinical success (by life-table analysis) was obtained by only 22.5% at 6 months, and only 13.5% at 12 months. Patients presenting with intermittent claudication did significantly better than those presenting for limb salvage (p = 0.01), and trends toward improved outcome were noted for short versus long lesions as well as for patients with "good" versus "poor" distal runoff (NS). Procedure-related morbidity occurred in 14%, and there was one peri-procedural mortality (1.8%). We conclude that the use of LABA is associated with long-term clinical success in only a small proportion of patients, and that widespread clinical application of this technique is not indicated at the present time.

Adult↗
PubMed1990

Increased infection rate in double-lumen versus single-lumen Hickman catheters in cancer patients.

Over the 48-month period from January 1983 through December 1986, 51 single-lumen (SL) and 94 double-lumen (DL) indwelling central venous (Hickman) catheters were placed in 118 patients with malignant disease. We reviewed these cases retrospectively to determine the types and frequency of complications requiring catheter removal. The catheters were in place a total of 18,397 days. Overall, 14% (7/51) of SL and 21% (20/94) of DL catheters were removed due to infection. Of those catheters becoming infected, DL catheters were infected earlier. SL catheters that became infected averaged 213 days of use before removal, whereas DL catheters becoming infected averaged only 78 days before removal (P less than or equal to .02). The infection rate was significantly less in SL (one infection per 1,210 days) than in DL catheters (one infection per 496 days) (P less than or equal to .02). Thus because of its significantly reduced risk of infection, the single-lumen Hickman may be the preferred catheter for long-term venous access in many patients.

Adult↗
PubMed1990

The use of composite grafts in femorocrural bypasses performed for limb salvage: a review of 108 consecutive cases and comparison with 57 in situ saphenous vein bypasses.

We retrospectively reviewed the results of 108 consecutive femorocrural bypasses performed with prosthetic/autogenous composite graft material and compared these with the results of 57 crural bypasses using greater saphenous vein by the in situ technique. Indication for operation in all cases was the salvage of an otherwise imminently threatened limb. Polytetrafluoroethylene-composite grafts (n = 87) and human umbilical vein-composite grafts (n = 21) were placed only in patients lacking suitable autogenous material for in-line reconstruction. Patient groups were similar with respect to mean age, prevalence of arterial disease risk factors, quality of the distal runoff, and location of the distal anastomosis. Cumulative patency rates at 1 year by life-table analysis were 81.9%, 34.6%, and 12.1% for the in situ, polytetrafluoroethylene-composite and human umbilical vein-composite groups, respectively. At 2 years these were 63.9%, 29.9%, and 6.0%, respectively (p less than 0.025). Cumulative limb salvage at 1 year was 70.6%, 62.3%, and 32.7%, respectively. Wound-related complications occurred in 52.4% of human umbilical vein-composite, 38.6% of in situ, and 18.3% of polytetrafluoroethylene-composite bypasses (p less than 0.05). On the basis of these results, we conclude that femorocrural bypass with polytetrafluoroethylene-composite graft is an acceptable form of distal reconstruction for limb salvage in patients lacking sufficient lengths of autogenous vein. We no longer use human umbilical vein for composite construction.

Aged↗
PubMed1988

The Kensey catheter: preliminary results with a transluminal atherectomy tool.

The Kensey dynamic angioplasty instrument is an atherectomy device approved by the Food and Drug Administration that uses a rotating cam tip housed within a flexible polyurethane catheter to recanalize obstructed and stenotic arteries. Twenty patients with significant femoral arteriosclerotic occlusive disease underwent attempted transluminal endarterectomy of 23 extremities with the Kensey catheter. Significant improvements of superficial femoral artery luminal diameter was achieved in 10 of 13 patients with stenosis and passage of the spinning catheter tip at 60,000 to 90,000 rpm through areas of complete occlusion was successful in 4 of 10 cases. Balloon dilatation was used as an adjunct to increase the diameter of the superficial femoral artery lumen in 11 of 14 successful cases. This preliminary report provides technical data and short-term follow-up of this new innovative vascular tool.

Angioplasty, Balloon↗
PubMed1987

Arterialization of reversed autogenous vein grafts: quantitative light and electron microscopy of canine jugular vein grafts harvested and implanted by standard or improved techniques.

To provide sequential, quantitative analysis of the cellular events occurring in reversed autogenous vein grafts after implantation and potential modifications of these events, two groups of veins were evaluated. Veins prepared by standard techniques of unmonitored pressure distension with cold heparinized saline solution, tributary ligation adjacent to the wall, and storage at 4 degrees C were morphometrically compared with veins harvested by means of a modified protocol of papaverine irrigation, tributary ligation away from the graft wall, pressure distension to 100 mm Hg with heparinized blood containing papaverine at body temperature, storage in identical solution at 4 degrees C, and implantation while distended. Unilateral jugular veins harvested from dogs with the modified technique (IRJV,N = 9) or standard technique (SRJV,N = 9) were implanted into carotid arteries, retrieved at 30 minutes, 2 days, and 10 days postoperatively along with the contralateral control vein after perfusion fixation in situ, and examined microscopically to quantitate intimal-medial thickness and endothelial damage (denudation and ultrastructural alterations). All IRJVs remained endothelialized, whereas SRJVs had 19% and 40% endothelial denudation at 30 minutes and 2 days, respectively, as well as massive neutrophil, platelet, and monocyte involvement. In contrast, IRJVs had only a modest infiltration of monocytes beginning early after implantation and culminating in their localization beneath endothelial cells; these endothelial cells increased in number during the 10-day period. Although SRJVs exhibited nearly complete reendothelialization over the luminal surface of macrophages by 10 days, endothelial damage was consistently higher than that of IRJVs at all periods and intimal-medial thickness was significantly greater at 10 days (65 +/- 0 vs. 57 +/- 0 micron, respectively; p less than 0.001). These findings suggest that endothelial preservation with improved harvesting techniques inhibits thrombosis and limits wall thickening and also that macrophages may play a protective role by promoting endothelial proliferation.

Animals↗
PubMed1987

Freshly harvested cadaveric venous homografts as arterial conduits in infected fields.

Six patients with patent multilevel prosthetic grafts (three axillofemoral-femoral grafts, an aortobifemoral graft, an axillofemoral and femoral-anterior tibial graft, and an axillofemoral and femoral-popliteal graft) that demonstrated overt infection involving both the proximal inflow (one infrarenal aorta, five axillary arteries) and groin anastomoses required complete graft excision. Cadaveric inferior vena cava, common and external iliac, common and superficial femoral, and greater saphenous veins were harvested in conjunction with multiple organ donor procedures. Identical anatomic reconstruction within the infected fields was accomplished, with patency and distal perfusion maintained for intervals sufficient to achieve complete resolution of infection in all cases. This interval of revascularization with a venous homograft has served as a temporizing maneuver, which permitted eradication of infection and allowed subsequent reimplantation of prosthetic graft material without associated reinfection in the two instances in which it was required. Use of freshly harvested large-caliber caval, iliac, and femoral homograft veins as arterial substitutes in infected fields has not been previously reported. Case histories and a review of the venous homografting literature are included.

Aged↗
PubMed1985

The mangled extremity syndrome (M.E.S.): a severity grading system for multisystem injury of the extremity.

The severely mangled extremity presents a challenge in appropriate surgical management. Very few objective data were found about this problem. To clarify the situation, criteria for a "mangled extremity' were defined, a multidisciplined approach employed, and a retrospective graduated grading system developed. Sixty consecutive trauma patients with severely injured extremities during the past 3 years were reviewed. Seventeen patients fit the category of Mangled Extremity Syndrome (M.E.S.). Injuries were retrospectively classified using a graduated grading system directed at four major tissue systems of the extremity involved (integument, nerve, artery, and bone). Additional scoring items were included to define the significance of trauma sustained outside the extremities. Patients who ultimately came to amputation could have been identified preoperatively at initial emergency evaluation utilizing this graduated grading system. Retrospective data suggest that a Mangled Extremity Syndrome Index (M.E.S.I.) of 20 is the dividing line below which functional limb salvage can be expected and above which limb salvage is improbable. Prospective application of this system, as well as an organized multidisciplined approach, could be useful in the identification of functionally retrievable versus probably irretrievable extremities, thus identifying and helping define the indications for amputation. The grading system criteria and results in these 17 patients form the basis of this report.

Adult↗
PubMed1984

Optimal techniques for harvesting and preparation of reversed autogenous vein grafts for use as arterial substitutes: a review.

Since the first successful use of an autogenous vein graft for arterial reconstruction by Gluck in 1898 and the establishment of the scientific basis for the use of veins as arterial substitutes by Carrell and Guthrie in the early 1900s, reversed autogenous veins have been used extensively in arterial reconstructive operations. Despite being the preferred material for reconstruction, reversed autogenous vein is not an ideal graft material. The primary problem is structural alterations in the implanted vein predisposing to graft failure. Most of these failures occur within the first few months after graft implantation and are though to be due, in part, to endothelial damage incurred during harvesting and preparation of the vein. This review focuses on technical aspects of vein graft harvesting associated with alterations in endothelial morphology including dissection technique, types of irrigation and storage solutions used, temperature of these solutions, distension pressures, and pharmacologic agents. An optimal technique incorporating subcutaneous and perivenous infiltration with papaverine, atraumatic dissection, controlled gradual distension, and storage of the distended vein in cold heparinized blood containing papaverine should produce grafts with improved endothelial preservation and patency rates compared with grafts harvested by techniques in widespread use at present. The importance of morphologically and functionally intact endothelium in reversed vein grafts, a comparison to that produced by in situ vein grafting, and its possible clinical implications are discussed.

Arterial Occlusive Diseases↗
PubMed1984

Carotid involvement in aortic dissection diagnosed by duplex scanning.

Symptomatic carotid dissection following repair of a proximal aortic arch dissection has been successfully diagnosed by noninvasive ultrasonic duplex scanning. Angiographic confirmation, follow-up examinations by duplex scanner, and conservative management with heparin anticoagulation and tight blood pressure control are discussed. The differing etiologies and potential neurologic complications following aortic root dissection vs. spontaneous cervical carotid dissection are considered with a review of the current literature. Although diagnosis can be achieved through arteriography, the combined modalities of duplex scanning allow evaluation of both anatomic and hemodynamic factors. Conservative therapy may prove the most appropriate mode of management in these neurologically unstable patients.

Aortic Dissection↗
PubMed1983

Autogenous graft replacement of infected prosthetic grafts in the femoral position.

Infected prosthetic grafts in the femoral position remain among the most challenging problems in vascular surgery. Over the past 2 years, 11 patients with this critical condition have undergone graft reconstruction with autogenous tissue as described by Ehrenfeld. All infected prosthetic material was removed and replaced by an autogenous graft. The autogenous grafts were constructed with endarterectomized superficial femoral, iliac, and aortic segments as well as portions of saphenous and cephalic veins. This procedure has proven successful, resulting in only one amputation (undertaken with a still functioning autogenous graft) in the series. There was one postoperative death. Six grafts failed in long-term follow-up, due in all cases to inadequate flow because of stenosis of the saphenous vein portion of the autogenous reconstruction. However, the patients were usually free of infection by this time and underwent successful prosthetic reconstruction.

Aorta, Abdominal↗
PubMed1982

Axillofemoral bypass: a ten-year review.

During a ten-year period (1969-1980), 106 grafts were implanted in the axillofemoral and axillobifemoral positions. This retrospective study is based on life table analysis of cumulative patency rates in both axillofemoral and axillobifemoral grafts, with and without thrombectomy. Dacron grafts were used exclusively from 1969 to 1979, and PTFE from 1979 to 1980. Cumulative patency for Dacron axillobifemoral grafts was 97 +/- 3% at 32 months (73 +/- 21% at 42 months). Patency in both unilateral and bifemoral grafts was significantly increased by thrombectomy. Dacron and PTFE axillobifemoral graft patency was not significantly different. Perioperative mortality was 8% in a group of patients whose survival rate at four years was only 50 +/- 10% from associated disease. Axillobifemoral grafting presents an alternative to aortoiliac reconstruction in elderly patients with severe associated disease in whom the risk of anatomic bypass is prohibitive.

Arterial Occlusive Diseases↗