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Biomedical subjects

R W Barnes

Publications and source records attributed to R W Barnes.

At least 91 records · Page 5Linked to original sources
PubMed1987

Human percutaneous laser angioplasty. Patient selection criteria and early results.

Percutaneous transluminal laser angioplasty is a new method for treating atherosclerotic disease previously not amenable to routine percutaneous transluminal angioplasty techniques. Our results compared favorably with other clinical trials. Patient selection criteria include lesions in the superficial femoral or popliteal system not capable of being treated with routine percutaneous transluminal angioplasty. We think that these lesions include high-grade stenoses or short segmental occlusions. Heavily calcified vessels and long segment occlusions measuring greater than 12 cm in length are probably not amenable to percutaneous transluminal laser angioplasty. The long-term results of this form of therapy for peripheral vascular disease remain unknown.

Aged↗
PubMed1987

Surgical handicraft: teaching and learning surgical skills.

Surgeons choose their profession with a strong desire to excel at manual therapeutic skills. Although we mime our mentors, we have often received the torch of technique in the absence of a systematic program to optimally develop our manual dexterity. The operating room is the ultimate arena to refine one's technical ability, but a surgical skills laboratory should assume increasing importance in introducing the trainee to the many nuances of the fine manual motor skills necessary for optimal surgical technique. Surgical educators should address the science of surgical handicraft in a manner similar to the science of preoperative and postoperative surgical principles that have been espoused over the past 40 years. Although it has been euphemistically said that "you can teach a monkey to operate," few of us have broken the process down into the basic elements to accomplish such a goal. In view of the increasing complexity of operations and equipment, the constraints on animal laboratories and teaching caseloads, and the mounting economic and medico-legal pressures, the development of optimal surgical skills should be a major objective of every surgical training program. By developing novel programs and scientifically evaluating the results of such endeavors, surgical faculties may find increased academic rewards for being a good teacher.

Functional Laterality↗
PubMed1986

Intraoperative monitoring in vascular surgery.

Doppler ultrasound and real-time B-mode ultrasonic imaging are useful techniques to monitor the technical success of reconstructive vascular operations. Gas-sterilized CW or pulsed Doppler probes permit audible or spectral detection of normal and abnormal blood velocity patterns associated with intimal flaps, thrombotic or platelet aggregates, retained venous valve cusps or arteriovenous fistulas. Real-time ultrasonic B-mode imaging allows detection of technical defects or thrombotic debris which is of particular importance in minimizing stroke or recurrent lesions following carotid endarterectomy. These ultrasonic techniques should become routine adjuncts for surgeons interested in defining localized pathology and hemodynamics, assuring technical integrity, detecting intraoperative defects, and predicting favorable outcome of vascular reconstruction procedures.

Endarterectomy↗
PubMed1986

Asymptomatic carotid disease in patients undergoing major cardiovascular operations: can prophylactic endarterectomy be justified?

This article reviews the published experience supporting or refuting the value of prophylactic endarterectomy in patients with asymptomatic carotid disease who are candidates for major cardiovascular operations. Reports of 1,483 patients subjected to staged or concomitant carotid endarterectomy and coronary artery bypass grafting reveal a perioperative stroke rate of 2.9%. Timing of carotid endarterectomy did not influence stroke rate, but staged procedures were associated with a significantly greater incidence of perioperative myocardial infarction and death. Studies of patients undergoing major cardiovascular surgical operations without prophylactic carotid endarterectomy reported a perioperative stroke rate of 2.7%, which is not significantly different from that of patients undergoing prophylactic carotid endarterectomy. However, the author's prospective study of such patients showed a significant incidence of late postoperative neurologic deficits, which are usually transient ischemic attacks. There is no evidence to justify routine prophylactic carotid endarterectomy of asymptomatic carotid disease before major cardiovascular operations. Patients not undergoing endarterectomy, however, should be given careful postoperative follow-up, because transient ischemic attacks may occur that require surgical intervention.

Cardiovascular Diseases↗
PubMed1986

Greenfield vena caval filter: rationale and current indications.

Prevention is the best therapy for deep venous thrombosis, but when this fails, prompt diagnosis and appropriate treatment can usually avoid lethal pulmonary embolism. Anticoagulation is the preferred treatment for thromboembolic disease because it prevents lethal pulmonary embolism and also arrests the underlying thrombotic process. However, in specific patients with documented pulmonary embolism or deep venous thrombosis, or who are at high risk that either of these will develop, anticoagulation therapy may be contraindicated, may fail to control the thrombotic process, or may offer inadequate protection from lethal pulmonary embolism. In these instances, or when a previous mechanical attempt has failed to prevent pulmonary embolism from a caval source, a Greenfield filter should be considered. The available information on the natural history of patients in these specific categories and subcategories is reviewed, and the indications for and timing of Greenfield filter placement are explained.

Filtration↗
PubMed1986

The blue toe syndrome: hemodynamics and therapeutic correlates of outcome.

We reviewed the limb and digit hemodynamics of 67 extremities of 48 patients evaluated for blue toe syndrome in our vascular laboratory during 7 years. These patients represented 1.4% of the arterial examinations during this period. Abnormal ankle/arm pressure indices (less than 0.9), signifying proximal arterial obstruction, were present in 31 limbs (47%). Toe/ankle indices were abnormal (less than 0.6) in 57 extremities (85%), indicating pedal or digital artery obstruction. Arteriograms were obtained in 40 of 64 extremities (63%) available for follow-up, which revealed atherosclerotic disease in 90% (aortoiliac 20%, femoropopliteotibial 30%, and combined 40%), aneurysm in 7.5%, and no disease in only one extremity (2.5%). Of 64 extremities followed for 1 to 84 months (mean, 26 months), only 28 (44%) manifested an uncomplicated outcome. Tissue loss was noted in 24 (38%), recurrent digital ischemia occurred in nine (14%), and 14 limbs (22%) required amputation of toe(s) (seven), forefeet (three) or legs (four). Nine patients (20%) died in the follow-up period. Outcomes did not correlate with limb or digit hemodynamics or with therapy (surgical in 31, medical in 11, or none in 22) except that tissue necrosis was more common in patients undergoing operation. The blue toe syndrome deserves recognition as an important sign of potential limb-threatening arterial disease, but the optimal therapy remains to be established.

Adult↗
PubMed1986

Recurrent versus residual carotid stenosis. Incidence detected by Doppler ultrasound.

A sterile Doppler probe was used for intraoperative monitoring of the integrity of carotid endarterectomy of 125 vessels of 107 patients. Our objective was to reduce the contribution of residual carotid lesions to recurrent stenosis, which was evaluated by Doppler spectrum analysis in the early (less than 3 months, 66 arteries) and late (3-77 months, mean 32 months, 47 arteries) postoperative period. Intraoperative Doppler monitoring detected residual occlusion in six (4.8%) external carotid arteries and stenosis in ten (8.0%) internal carotid arteries permitting selected arteriography and correction of all significant lesions. Follow-up revealed one (1.5%) asymptomatic common carotid occlusion at 6 weeks and three (6.4%) asymptomatic internal carotid stenoses at 6, 10 and 25 months after operation. When compared to previous published experience, these results suggest that intraoperative correction of residual carotid obstruction detected by Doppler ultrasound may reduce the incidence of postoperative "recurrent" carotid stenosis.

Adult↗
PubMed1986

Noninvasive evaluation of peripheral vascular disease: recent advances and future implications.

Noninvasive diagnostic techniques have become a recognized adjunct in screening and follow-up of patients with peripheral arterial, venous, and cerebrovascular diseases. These techniques provide physiologic information at little or no risk to patients. Although primarily of diagnostic intent, these studies are also expanding our knowledge base about the natural history of peripheral vascular diseases and the efficacy of various interventions. Advances in radiology have complemented but not replaced the need for the noninvasive peripheral vascular laboratory. It is incumbent upon all physicians to appreciate the diagnostic value and recognize the limitations of these noninvasive techniques. Intelligent use of these modalities may enhance patient care without significantly increasing health care costs. Further prospective studies of the cost benefit or effectiveness of these techniques are indicated.

Arterial Occlusive Diseases↗
PubMed1986

111 In-labeled leukocytes in the detection of prosthetic vascular graft infections.

Making a clinical diagnosis of infection in prosthetic vascular grafts is difficult but when undiagnosed, this condition has a high mortality rate. Using Indium-111-labeled white-blood cells, 30 scans were performed in 21 patients suspected of having a prosthetic graft infection. The diagnosis of infected graft was confirmed by surgery in all cases, and lack of infection was established by resolution of symptoms with conservative therapy. Twenty-four hour scans of autologous Indium-111 leukocytes were obtained, and correlative CT studies were done in 11 cases. There were 13 infected grafts at surgery (purulent material present), and scans were positive in all (100% sensitivity); of 17 scans, there were 15 true negatives and two false positives (88% specificity). Using the criteria of gas or fluid around the graft, the sensitivity of CT was only 37% in a small subset of these patients. One-half of the cases in which infection was suspected clinically had no infection and had negative scans. Various types of grafts and graft materials were used, and there was no correlation with presence or absence of infection on the basis of the type of graft. Extragraft infection sites were found in five patients. In conclusion, use of Indium-111 leukocytes has been found to be an accurate and valuable diagnostic method for evaluation of suspected prosthetic vascular graft infection, and to have higher diagnostic accuracy than CT.

Aged↗
PubMed1986

Angioscopically monitored saphenous vein valvulotomy.

Angioscopy was used during in situ saphenous vein bypass grafting in seven patients. We were able to visualize valve incision, immediately identify and correct incomplete valvulotomy, identify side branches as potential arteriovenous fistulas, and assess distal anastomotic integrity. We encountered no retained valve cusps after angioscopy, as verified by Doppler ultrasound and completion angiography. Angioscopy verified distal anastomotic integrity in all patients with distal vein grafts large enough to accept the angioscope. Angioscopy requires minimal time, is relatively easy to use, serves as an adjunct to Doppler ultrasound and completion angiography, and has future potential as a therapeutic tool.

Aged↗
PubMed1985

Noninvasive assessment of atherosclerosis in nonhuman primates.

Atherosclerosis is a progressive and degenerative disease of the artery wall which begins relatively early in life, years if not decades prior to the onset of clinical signs and symptoms. One of the major challenges which face investigators in this field of research is to establish the validity and reliability of noninvasive methods which can detect atherosclerotic plaques before they become severe enough to result in tissue ischemia, and to determine whether or not atherosclerotic lesions can be monitored both in terms of rate and direction over time. Although several methods of direct arterial visualization are available currently, high-resolution B-mode ultrasound imaging appears to have the most advantages. This technique is noninvasive, relatively inexpensive, and can visualize not only lumen contour and configuration, but also the atherosclerotic plaque in the underlying wall. Preliminary experiments in animal models suggest that lesions as small as 0.5 mm in the carotid arteries can be detected using this method. Whether or not atherosclerotic plaques can be monitored over time, however, has not been demonstrated.

Animals↗
PubMed1985

Cardiovascular effects of protamine sulfate are dependent on the presence and type of circulating heparin.

Man's response to clinical doses of protamine is highly variable. We investigated the influence of circulating heparin in nine swine (mean age 6 weeks, weight 10 kg). Through a sternotomy we implanted an electromagnetic flow probe around the pulmonary artery for cardiac output determination and catheters into the ascending aorta, pulmonary artery, right atrium, and left atrium for pressure monitoring. Each animal was allowed to recover and was studied awake on 3 consecutive days. Protamine, 3 mg/kg, beef lung heparin, 300 U/kg, and pork mucosal heparin, 300 U/kg, followed by protamine, were given in rotation by intravenous bolus. Protamine alone had no effect. Beef lung heparin followed by protamine induced a marked increase in pulmonary artery pressure (mean 38 +/- 3 to 51 +/- 5 mm Hg in 3 minutes). Pulmonary vascular resistance doubled (mean 0.12 +/- 0.01 to 0.23 +/- 0.04 R within 4 minutes), returning to normal within 15 minutes. Cardiac index and aortic pressure changed minimally. Pork mucosal heparin followed by protamine induced a similar but greater increase in mean pulmonary arterial pressure; however, cardiac index fell significantly (p less than 0.05, 207 +/- 16 to 117 +/- 16 ml/kg/min-1 at 1 minute) despite a regular rhythm and adequate left atrial filling pressure. Thus cardiac contractility was depressed. Systemic hypotension occurred in three of nine pigs. Both mean pulmonary vascular resistance and systemic vascular resistance increased (0.12 +/- 0.01 to 0.67 +/- 0.25 R and 0.40 +/- 0.04 to 1.09 +/- 0.25 R, respectively), significantly (p less than 0.05) more with pork than beef heparin. These data demonstrate that cardiovascular response to protamine neutralization varies significantly in regard to the type of heparin used. Furthermore, circulating heparin is required to produce those effects previously attributed to protamine alone.

Animals↗
PubMed1985

Late outcome of untreated asymptomatic carotid disease following cardiovascular operations.

In a previous prospective study of 449 patients undergoing coronary or peripheral arterial reconstruction, 85 patients had preoperative evidence of asymptomatic bruit and/or greater than 50% carotid obstruction by routine Doppler screening. No patient had prophylactic carotid endarterectomy. This article reviews the late postoperative outcome (2 to 61 months, mean 35 months) of 67 patients with asymptomatic carotid disease who survived operation without perioperative deficit. Eleven patients died (16%) including four of myocardial infarction and two of stroke. Neurologic deficits occurred in the late postoperative period in 22 patients (32.8%) after an average interval of 31 months, including transient ischemic attacks in 15 patients (22.4%); only four of these 15 were appropriate to the side of carotid disease documented preoperatively. Seven patients (10.4%) suffered stroke, only three (4.5%) of which were in the territory of carotid disease detected preoperatively. The cumulative rate of carotid disease progression was 34%, including three patients who suffered carotid occlusion. Two of the latter had the only fatal strokes. This study suggests that patients with asymptomatic carotid disease, although not at significant risk of perioperative stroke, require careful follow-up for late postoperative neurologic deficits, the majority of which (68%) are transient ischemic attacks.

Adult↗