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Biomedical subjects

M D Clark

Publications and source records attributed to M D Clark.

At least 37 records · Page 2Linked to original sources
PubMed1997

Traumatic carotid artery dissection and pseudoaneurysm treated with endovascular coils and stent.

PURPOSE: To report a case of post-traumatic internal carotid artery dissection and pseudoaneurysm formation at the C-1 level successfully treated by a percutaneous endovascular technique. METHODS AND RESULTS: A 20-year-old female presented 72 hours after a motor vehicle accident with incomplete occulosympathetic paresis (Horner's syndrome), carotidynia, and leftsided 1.5-cm x 2.5-cm pseudoaneurysm at the C-1 level. Neuroradiologists embolized the pseudoaneurysm with Guglielmi detachable coils and controlled the dissection with placement of a Wallstent. CONCLUSIONS: This report illustrates successful percutaneous endovascular treatment of a carotid dissection and pseudoaneurysm near the base of the skull.

Accidents, Traffic↗
PubMed1996

Extraluminal endoscopic-assisted ligation of venous tributaries for infrainguinal in situ saphenous vein bypass: a preliminary report.

In an attempt to obviate the need for an incision the length of the leg during in situ saphenous vein bypass, a minimally invasive operation using 'laparoscopic techniques' was developed. At operation, standard incisions were made over the proximal femoral artery/vein and the saphenous vein at the distal popliteal artery level. An angioscopic valvulotome was used to perform valvulotomy under direct vision. After valvulotomy, a distention balloon system was used to form a 'pocket' into which a laparoscope was inserted. Trocars were then inserted under direct vision and the saphenous vein dissected and side branches individually clipped. After occlusion of the venous side branches, proximal and distal arterial anastomoses were performed in the standard fashion. This minimally invasive operation using laparoscopic techniques precludes the need for a long leg incision and saphenous vein dissection, except at the proximal and distal arterial anastomoses.

Aged↗
PubMed1995

Preoperative control of a ruptured anastomotic femoral "pseudoaneurysm" by balloon catheter: a combined radiologic and surgical approach.

Inflow control of a rapidly expanding or ruptured femoral anastomotic "pseudoaneurysm" can be fraught with hazard. Occlusion of an anastomotic femoral aneurysm with a balloon catheter offers the surgeon a simple method of gaining inflow control prior to surgery. After achieving inflow control with the balloon catheter, the surgeon can incise the anastomotic aneurysm without significant blood loss, control back bleeding with balloon occlusion catheters, and with relative ease and safety repair or replace the anastomotic aneurysm as indicated. An illustrative case is presented.

Anastomosis, Surgical↗
PubMed1994

Infrainguinal endovascular in situ saphenous vein bypass: ongoing results.

PURPOSE: With 70 cm "cutter" valvulotomes for valvulotomy and an electronically steerable nitinol catheter to occlude venous tributaries with platinum coils, endovascular in situ saphenous vein (EISV) bypass can be safely performed from within the saphenous vein. To determine whether EISV bypass could reduce hospital length of stay (LOS) and perioperative morbidity without compromising patency, another 53 EISV bypasses for limb salvage were performed. METHODS: Tributary occlusion was accomplished with only fluoroscopic surveillance with a new, smaller, and more steerable silicone-tipped nitinol catheter. RESULTS: Two (3.7%) wound complications occurred. The mean hospital LOS after operation was 4.2 days (range 2 to 29 days). All tributaries initially embolized remained occluded, and three "missed" arteriovenous fistulas were identified during follow-up extending to 15 month (mean 8.4 months). Eighty-eight percent (49 of 54) of phase II bypasses remained patent, whereas life-table analysis of all bypasses (phase I and II) was 77% (69/99) at 24 months follow-up (mean 13.6 months). By comparison, 41 infrainguinal saphenous vein in situ bypasses with "classic" open techniques were performed concurrently. The mean postoperative LOS was 11.6 days (range 4 to 42 days), wound complications occurred in 24% (10) of patients, and two "missed" arteriovenous fistulas were identified during follow-up. Eighty-three percent (34 of 41) of bypasses remain patent at 24 months follow-up (mean 16.2 months). CONCLUSIONS: If EISV bypass long-term patency rates remain similar to classic in situ bypass patency results, the additional benefits of decreased hospital LOS, reduced wound-related complications, shortened recuperation, and therefore increased health care savings gives this endovascular technique strong consideration as the possible future operation for infrainguinal saphenous veins in situ bypass.

Aged↗
PubMed1994

Use of the Greenfield filter in patients with major trauma.

Patients with major trauma often cannot be given the benefit of preventive measures such as pneumatic compression boots and low-dose heparin against pulmonary embolism. The Greenfield filter is accepted as a safe and effective method of prophylaxis of this complication. The aim of this study was to evaluate the efficacy of placement of the Greenfield filter in 161 patients with major trauma. Between January 1984 and July 1988, 94 patients with an injury severity score (ISS) of > 16 were treated. This score is predictive of a mortality rate of at least 10% and defines major trauma based on anatomic injury. Some 20% (19 of 94) of these patients developed deep vein thrombosis despite standard prophylactic measures and 8% (eight of 94) suffered pulmonary embolism, two of which were fatal. Pulmonary embolism occurred without antecedent evidence of deep vein thrombosis in another 15% of patients (14 of 94), three of which caused death. From August 1988 until July 1992, of 67 other patients with an ISS > 16, 13% (nine of 67) developed deep vein thrombosis and 1% (one of 67) had a pulmonary embolism; this was not statistically significant (P > 0.25). Of these 67 patients who were considered to be at high risk of pulmonary embolism, because of a contraindication to anticoagulation or physical impediment to sequential compression boots, 29 had prophylactic placement of a Greenfield filter. No pulmonary emboli occurred in these patients. During long-term follow-up (mean 32.8 (range 4-58) months), 84% of the surviving patients (21 of 25) underwent duplex ultrasonography of the inferior vena cava; patency of the vessel was confirmed in all patients.

Adolescent↗
PubMed1993

NMR measurements of Na+ and cellular energy in ischemic rat heart: role of Na(+)-H+ exchange.

Interleaved 23Na- and 31P-nuclear magnetic resonance (NMR) spectra were continuously collected on perfused rat hearts subjected to low-flow ischemia (30 min, 10% flow) or zero-flow ischemia (21 min) followed by reperfusion. During untreated low-flow and zero-flow ischemia, intracellular Na+ (Nai+) increased by 53 +/- 11 (+/- SE) and 78 +/- 8%, respectively, and remained elevated for zero-flow hearts. However, during both low- and zero-flow ischemia, Nai+ did not increase in hearts treated with the Na(+)-H+ exchange inhibitor, 5-(N-ethyl-N-isopropyl)amiloride (EIPA). The pH decreases during ischemia were unchanged. EIPA treatment reduced ATP depletion during ischemia. During reperfusion from zero-flow ischemia, EIPA-treated hearts displayed more rapid and extensive recoveries of phosphocreatine and ATP. Recovery of left ventricular developed pressure was improved for zero-flow hearts treated with EIPA during the ischemic period exclusively (104 +/- 13%) compared with untreated hearts (36 +/- 21%). These data indicate that Na(+)-H+ exchange is an important mechanism for Nai+ accumulation, but not for pH regulation, during myocardial ischemia. Additionally, Nai+ homeostasis plays an important role in the postischemic recovery of cellular energy and ventricular function.

Amiloride↗
PubMed1992

Amaurosis fugax: is it innocuous?

A 10 year retrospective study of 103 patients with amaurosis fugax was done. Sixty-two patients with symptoms of amaurosis fugax underwent arteriography, which demonstrated ulcerated carotid plaque in 36 and hemodynamically significant stenoses (greater than 75% diameter reduction) in 26. These 62 patients underwent carotid endarterectomy. The other 41 patients who had proven ulcerated plaque (33 patients) or hemodynamic stenoses (eight patients) were not treated surgically and served as a control series. No strokes or deaths occurred in the immediate postoperative period. Follow-up of the 62 operated patients extending to 10 years (mean 4.2 years), revealed one (1.6%) patient with recurrent amaurosis fugax symptoms, two (3.2%) with transient ischemic attacks, and one (1.6%) with a stroke in the operated hemisphere. In the nonoperated group, despite aspirin or warfarin treatment, four (9.7%) patients had ongoing amaurosis fugax symptoms, and two (4.8%) developed transient ischemic attacks that led to carotid endarterectomy. One (2.4%) other patient developed sudden, permanent monocular blindness, and two (4.8%) suffered hemispheric strokes, one of which was fatal. The cumulative morbidity (ongoing ocular or transient ischemic attack symptoms, perioperative and late stroke) in the operated group was 6.4% (four patients), while the cumulative morbidity in the nonoperated group was significantly higher at 21.9% (nine patients) (p = 0.02). When patients present with symptoms of amaurosis fugax and have demonstrable carotid bifurcation disease, carotid endarterectomy is recommended. Amaurosis fugax should be regarded as a harbinger of monocular blindness and stroke.

Adult↗
PubMed1991

When the same is different. A comparison of the information processing strategies of deaf and hearing people.

In this study, the information processing strategies of Gallaudet University students who are profoundly and prelingually deaf were evaluated. The subjects demonstrated the highest levels of recognition to the left and right of the fixation point, often referred to as a reading strategy when found in hearing people. Additionally, they demonstrated higher levels of recognition at positions in the top right quadrant of the display, a pattern not found in hearing people. A main effect was found: subjects whose primary and secondary school backgrounds were oral and manual combined had significantly higher levels of recognition overall than did subjects from oral-only educational backgrounds. Differences in background did not interact with strategy use in this study. These findings lead to the conclusion that the information processing strategies of deaf people need to be evaluated closely before general conclusions can be made. Alternative means for evaluating these types of findings are suggested.

Adult↗
PubMed1990

Case report 589: Use of Ostamer in fusion of lumbar spine, postoperative appearance.

In the late 1950s and early 1960s there was intense orthopedic interest in a plastic polyurethane foam (Ostamer) that could be used in the fixation of fractures, performance of arthrodesis, and in spinal fusions. It saw limited success at that time but eventually fell from favor. A patient presenting with a draining sinus in the buttock, back pain, and a history of lumbar spinal fusion with Ostamer was recently scanned in our department. The CT appearance of Ostamer and a brief review of the literature are reported.

Bone Cements↗
PubMed1990

Carotid patch angioplasty: immediate and long-term results.

To determine the benefit of carotid patch angioplasty, a retrospective study of 1000 consecutive carotid endarterectomies was done. Based on the type of carotid endarterectomy closure, patients were divided into four groups: 250 had primary closure, 250 had expanded polytetrafluoroethylene patch, 250 had Dacron patch, and 250 had saphenous vein patch. On the basis of operative technique or type of carotid artery closure, no statistical difference was found in the incidence of postoperative stroke (p greater than 0.25): primary closure 1.6% (4), expanded polytetrafluoroethylene 2.0% (5), Dacron patch 1.6% (4), and saphenous vein patch (0). Postoperative carotid patency was determined by B-mode ultrasonography, and 717 patients were evaluated in follow-up extending to 6 years (mean 37.8 months). Based on the method of carotid endarterectomy closure, no significant difference (p greater than 0.25) was found in the incidence of significant restenosis (greater than 50% diameter reduction): primary closure 4.0% (7), expanded polytetrafluoroethylene 4.0% (6), Dacron 5.4% (9), and saphenous vein 1.0% (2). Significant restenosis was most frequent in habitual smokers (93%, 25/28) and females (78%, 22/28) despite the method of carotid endarterectomy closure. No statistical difference was found in the incidence of late ipsilateral stroke either (p greater than 0.25): primary closure 2.9% (5), expanded polytetrafluoroethylene 2% (3), Dacron 5% (3), and saphenous vein 0%. These results indicate that the incidence of postoperative stroke, regardless of method of arterial closure, was not statistically different. The method of carotid closure did not appear to affect the occurrence of late ipsilateral stroke or restenosis; however, patch angioplasty with saphenous vein appears appropriate in habitual smokers, and likely in patients with small internal carotid arteries.

Blood Vessel Prosthesis↗
PubMed1989

Massive pulmonary embolism: triple-armed therapy.

Many patients who suffer a massive pulmonary embolus die despite emergent therapy. In these desperately ill patients an aggressive, combined method of management was initiated to improve their chances and quality of survival. During a 5-year period 10 patients were treated with (1) low-dose topical, intrapulmonary thrombolytic therapy to dissolve thrombus, (streptokinase or urokinase); (2) anticoagulation to prevent thrombus propagation (heparin); and (3) the simultaneous insertion of a Greenfield filter to prevent the early, recurrent, and therefore potentially fatal pulmonary embolus--"triple-armed therapy." Thrombolytic therapy was administered through a Swan-Ganz catheter wedged against the pulmonary embolus. During the same interval 10 other patients also sustained massive pulmonary emboli but were treated only with systemic heparin. Serial pulmonary arteriography was performed daily. The patients treated by triple-armed therapy responded favorably with a rapid (less than 6 hours), significant improvement in PaO2, pulmonary artery pressure, cardiac output, pulmonary vascular resistance, and blood pressure, compared with patients treated with continuous heparin alone. Nine patients in the triple-armed therapy group survived whereas only six in the heparin group survived. Two additional patients were treated by triple-armed therapy and had thrombolysis with triple-armed therapy with tissue plasminogen activator; these patients demonstrated the most rapid improvement in cardiorespiratory dynamics and arteriographic clearance of emboli. This management protocol shows promise for patients who sustain a massive pulmonary embolus, because it reduces the morbidity associated with pulmonary embolectomy while avoiding the hazards associated with systemic thrombolytic therapy.

Aged↗
PubMed1989

Preventing drug dependency: Part 2, Educating and supporting staff.

Nurse administrators can respond to the chemical abuse problem in one of two ways. They can deny it, ignore it, avoid confrontation, and terminate the employee. Such action jeopardizes both the nurse and patients. Alternatively, nurse administrators can deal with the problem by recognizing its prevalence in society, educating their personnel, providing support systems for staff, and establishing controls. By choosing this latter course of action, nurse managers evidence humanity and concern for patients, the profession, and individual practitioners.

Career Mobility↗
PubMed1988

Carotid endarterectomy after reversible ischemic neurologic deficit or stroke: is it of value?

The benefit of carotid endarterectomy (CE) in preventing recurrent stroke and improving survival in the patient who has sustained a reversible ischemic neurologic deficit (RIND) or stroke is still controversial. To determine the long-term benefits and value of CE in these patients, a 10-year review of 253 patients who suffered a RIND or stroke was conducted. All patients had CT brain scans, as well as arch, extracranial, and intracranial arteriography; any patients without demonstrated carotid bifurcation disease were excluded from the study. On the basis of clinical symptoms and CT scan findings, 66 patients were categorized as having sustained a RIND and 187 a stroke. One hundred fifty-one patients who suffered a RIND or stroke had CE, whereas 102 patients with RIND or stroke did not have CE and served as a control group. All endarterectomies were performed with a temporary indwelling shunt. Postoperative complications included two deaths (1%), six strokes (4%), and 10 transient neurologic deficits (7%). In follow-up extending to 10 years the cumulative incidence of recurrent stroke was only 7% (11 patients) in the operated group, whereas 18% of patients in the nonoperated control group (18) sustained a recurrent stroke (p less than 0.05). As anticipated, the leading cause of death during follow-up was cardiac related; although CE did not significantly improve long-term survival, there was more than a twofold decrease in the incidence of recurrent stroke as a cause of death in the group having CE.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1988

Preventing drug dependency: Part I, Recognizing risk factors.

Nurse administrators are in a key position to develop strategies to deter drug abuse by their staff. This two-part series of articles discusses the development of a prevention program. This first article describes risk factors associated with initial and continuing drug use by nurses. The second article (January 1989) will present an educational program based on these risk factors and suggest ways to provide staff with support.

Attitude of Health Personnel↗
PubMed1987

Carotid endarterectomy to correct asymptomatic carotid stenosis: ten years later.

The ideal management of the patient with an asymptomatic stenosis of the extracranial internal carotid artery remains controversial. The purpose of this article was to evaluate the effects of prophylactic carotid endarterectomy (CE) done to treat asymptomatic carotid stenosis (greater than 50% diameter reduction by angiography) 10 years later. In 1976, 42 prophylactic CEs were performed. There were no postoperative deaths or strokes. During 10-year follow-up two strokes occurred in the operated hemisphere; one stroke was fatal and was due to an intracranial hemorrhage, whereas the other stroke was thromboembolic in origin. Two other patients suffered strokes in the contralateral hemisphere and seven patients had transient ischemic attacks in the contralateral hemisphere, which necessitated CE. The survival rate at the end of the study period by life-table analysis was 57% (mean 8.7 years). Sixteen late deaths occurred, with coronary artery-related disease the most common cause of death. This review with actual 10-year follow-up demonstrated that prophylactic CE may be performed with minimal risk, that late stroke in the operated hemisphere was negligible, and that long-term survival was similar to that of a comparable age-matched population, possibly because late deaths attributed to stroke were reduced. On the basis of long-term follow-up, CE to treat asymptomatic high-grade carotid stenoses appears to be indicated in appropriate patients.

Actuarial Analysis↗