Search PubMed⌕ Search

Biomedical subjects

G J Collins

Publications and source records attributed to G J Collins.

At least 73 records · Page 4Linked to original sources
PubMed1978

Missile emboli.

Missile emboli remain unusual and challenging problems. Failure to recognize and adequately manage these uncommon lesions can result in loss of limb and/or life. No one individual or medical center has an extensive experience with missile emboli. An analysis of approximately 7,500 Vietnam casualties with known vascular trauma revealed an incidence of about 0.3%: 22 patients with missile emboli. The majority were associated with fragments from explosive devices and involved the arterial system. The missile emboli were removed in all but three patients. Only one patient had a vascular complication. There was no mortality or amputation in this series.

Adult↗
PubMed1978

Coagulation abnormalities in patients undergoing myocardial revascularization.

One hundred patients were screened for hypercoagulability preoperatively and on the third, seventh, tenth, fourteenth, and twenty-first days postoperatively. Patients found to have hypercoagulability were treated with heparin, aspirin, and Coumadin. When the abnormality was present preoperatively, treatment was continued for the duration of the patient's life. Those patients in whom abnormalities developed postoperatively were given anticoagulants until cardiac catheterization 6 months following their operation. Twenty-four of the 100 patients had no coagulation abnormalities preoperatively or postoperatively. Fifteen patients were found to have abnormality prior to operation. Their predominant abnormality was low antithrombin III activity. Sixty-one patients became hypercoagulable postoperatively. Predominant abnormality in this group of patients was increased thrombin generation and increased platelet adhesiveness. Evaluation of patients in this study group revealed a decrease in the incidence of pulmonary embolism, an increase in the patency of vein grafts, and the elimination of anticoagulant therapy in 24 percent of the patients.

Anticoagulants↗
PubMed1978

Problems and resolution of lower extremity venous disease.

Venous aberrations in the lower extremity, whether acute or chronic, have disastrous effects on individual patients, their families, and society in general. Whether the challenge is the treatment of varicose veins or that of maintaining patency of a venous reconstruction, it is obvious that many questions remain unanswered. Additional experimental research and clinical experience must be documented in carefully organized scientific studies.

Humans↗
PubMed1978

Platelets, thromboembolism and the clinical utility of antiplatelet drugs.

Experience has established a major role for platelets in the pathogenesis of a variety of thromboembolic disorders. Despite advances in several areas, many problems remain. The relevance of platelet function testing to thromboembolic disorders needs clarification. Whether the association of enhanced platelet function and the aforementioned disorders represents cause, effect or nonspecific accompaniment is unknown. The concept of identifying individuals at risk by platelet function testing is attractive but unproved. Whether such individuals would benefit from prophylactic antiplatelet therapy is also unknown. For treatment of most established thromboembolic disorders as well as prophylaxis, the place of antiplatelet drugs is not established. Whether this form of therapy is superior to conventional treatment, adjunctive or of no benefit is not resolved in most instances. Also, the most appropriate antiplatelet drug or combination of drugs, and in which dosages for specific disorders, remains unclear. Well designed, prospective clinical investigation, although cumbersome and time-consuming, will be necessary to answer most of these questions. A final problem area concerns research into the pharmacology of platelet inhibition. It is probable that the ideal antiplatelet agent remains undiscovered. Currently, several investigators are looking into the possibility of manipulating prostaglandin metabolic pathways in hopes of specifically blocking thromboxane generation while allowing production of metabolites inhibitory to aggregation. This exciting approach and other investigations into the biochemical basis of platelet function should lead to the discovery of new antiplatelet agents.

Animals↗
PubMed1978

Heparin utilization during arterial revascularization.

These studies demonstrate that therapeutic levels of heparin are achieved when either 100 u/kg or 150 u/kg are administered prior to arterial or aortic cross clamping during peripheral vascular reconstructive procedures. They further demonstrate that adequate levels of heparin are maintained for at least one hour even with the lower dosage. If heparin effect is not reversed, many patients will be returned to the recovery ward with therapeutic levels of heparin. This is undesirable and can be averted by administering appropriate doses of protamine sulfate. Excesses of protamine sulfate should be avoided since unbound protamine sulfate has anticoagulant as well as cardiovascular effects.

Clinical Trials as Topic↗
PubMed1978

Routine operative arteriography during carotid endarterectomy: a reassessment.

One hundred and thirty-one consecutive operative arteriograms done in conjunction with carotid endarterectomy are reported. Radiographically obtrusive defects were found in 5.3% of arteriograms, with 1.5% in the common carotid artery, 2.3% in the external carotid artery, and 1.5% in the internal carotid artery. Potential complications were introduced by the operative arteriograms in 2.3% of the patients. One patient developed a persistent hemiparesis thought to be related directly to the performance of the arteriogram. On the basis of this review, routine operative arteriography as an adjunct to carotid endarterectomy has been discontinued at out institution. Specific indications for obtaining operative arteriograms are outlined.

Angiography↗
PubMed1978

Limb salvage by extended profunda femoris revascularization.

We would conclude from the present series that if there is an adequate descending branch of the profunda femoris artery (20--25 cm), revascularization of the profunda femoris artery is worthwhile even in the presence of marked distal ischemia. In the present series, early success was manifested by relief of rest pain, healing of ischemic ulcers, and elevated ankle pressures (86%). The late success rate was 73%. If the proximal revascularization fails, distal bypasses can be added at a later procedure.

Adult↗
PubMed1978

Vena caval interruption in pulmonary hypertensive canines.

Massive pulmonary embolism regularly causes a reduction in systemic arterial pressure. This is accompanied by an increase in pulmonary arterial pressure. If right heart strain is sufficient, peripheral venous pressures also rise. Initial cardiac output and heart rate responses are variable, but with the progression of time, cardiac output almost uniformly falls. When either vena caval clipping or vena caval ligation are performed in the face ot these altered hemodynamics, there is a further reduction of systemic arterial pressure and cardiac output. After a period of 90 to 120 minutes, the effects of the two procedures appear to be equivalent. This is thought to be on the basis of opening of venous collateral pathways in the case of vena caval ligation. Therefore, when sufficient venous collaterals are present, the major determinant of the ultimate outcome is the impact of the embolus itself rather than the type of procedure used to interrupt the inferior vena cava.

Animals↗
PubMed1977

Coagulation abnormalities in patients with arterial, venous, and combined arterial and venous thromboses.

Thrombotic disorders are much more common than hemorrhagic disorders. Nonetheless, most knowledge of coagulation relates to the hemorrhagic disorders. We have done extensive coagulation evaluations in patients with arterial thromboses only, venous thromboses only, and in patients with combined arterial and venous thromboses. Prominent abnormalities in platelet aggregation, factors VIII, IX, and XI levels, and fibrinogen were noted in all groups. These types of studies should eventually lead to a fuller understanding of thrombotic disorders.

Adolescent↗
PubMed1977

The effects of operative stress on the coagulation profile.

There is a tendency toward hypercoagulability in the postoperative period. This is manifested by changes in a number of coagulation parameters, and if not offset by some protective mechanism, thrombosis may occur. This protection appears to be mediated more through the fibrinolytic mechanism than through the action of antithrombin 3 (AT-3) because AT-3 activity diminishes in the early postoperative period. The introduction of variables such as invasion of the vascular system, intraoperative heparin administration, administration of whole blood, and insertion of a Dacron prosthesis does not appreciably affect the response of the coagulation profile to operative stress.

Abdomen↗
PubMed1977

Carotid-axillary bypass: clinical and experimental evaluation.

Successful carotid-axillary bypasses have been performed nine times at Walter Reed Army Medical Center during a six year period starting in 1970. Although this approach has been of particular value in patients with symptomatic posttraumatic subclavian arterial occlusions, in whom local fibrosis creates additional problems is dissection and identification of important structures, carotid-axillary bypasses can also be used for lesions of the subclavian and/or axillary artery including aneurysms, ulcerations with distal embolism, and extensive arteriosclerotic occlusive disease. Our experimental data corroborate the clinical impression that carotid-axillary by-passing can be a safe and successful approach to surgical management of subclavian arterial lesions without creating any major significant hemodynamic derangements.

Adult↗
PubMed1977

Venous trauma: successful venous reconstruction remains an interesting challenge.

Ligation of some major veins can produce deleterious effects. Based on clinical and experimental research, there is a recent increased interest in repairing injured veins. Despite remaining limitations, successful venous repair has been possible without complications of thrombophlebitis or pulmonary embolism.

Follow-Up Studies↗
PubMed1977

Pitfalls in peripheral vascular surgery: Disseminated intravascular coagulation.

Disseminated intravascular coagulation is infrequently encountered in the practice of peripheral vascular surgery. Nonetheless, it has devastating and often fatal effects. In our series of eight cases, the mortality rate was 62.5 per cent. A better understanding of the basic disease process as prompted by this review, earlier diagnosis, and rational treatment should lead to higher survival rates and lowered morbidity.

Aged↗
PubMed1977

Multiple mycotic aneurysms due to Candida endocarditis.

Candida endocarditis is a serious condition which should be suspected in any patient with signs and symptoms compatible with bacterial endocarditis when cultures are negative. It should be managed by a medical-surgical approach which combines resection of all infected heart tissue and repair of any preexisting heart defects with appropriate antifungal therapy. Mycotic aneurysms should be treated by ligation of the vessel above and below the aneurysm, resection of the aneurysm, and implementation of appropriate antifungal or antibacterial therapy. Revascularization is not always necessary. When required, an extra-anatomic approach is preferable to placing a graft through the bed of the aneurysm.

Adult↗
PubMed1977

Autogenous venous interposition grafts in repair of major venous injuries.

1) This review of 51 former Vietnam casualties who had lower extremity venous injuries repaired using autogenous interposition venous grafts is the largest series of this type of venous repair to be reported. Nevertheless, additional information is needed, including more extensive phlebographic documentation of the current status of venous reconstructions. 2) The results of these venous repairs performed by essentially a different surgical team in every case are encouraging. Only one patient, or 2.0% of the total, developed thrombophlebitis in the postoperative period and this was transitory in nature. No patients developed pulmonary embolism. There was no edema in the postoperative period in 66.6% of the total. During the longterm followup, only six patients, or 11.8%, had residual edema. This is in marked contrast to a similar number of patients followed in the Registry who had ligation of popliteal veins following trauma with persistent edema in 50.9%. 3) Although this study remains incomplete, the favorable data should stimulate interest in performing additional repair of major lower extremity venous injuries utilizing autogenous venous grafts. Expanded experimental and clinical research is needed to define a readily available conduit of variable sizes which can be utilized successfully in reconstruction of the low-flow venous system.

Adult↗
PubMed1977

Fibromuscular dysplasia of the internal carotid arteries.

Seven patients with fibromuscular dysplasia of the internal carotid arteries have been operated upon at Walter Reed Army Medical Center. One lesion was treated by graduated dilatation with Bake's dilators combined with resection, end-to-end anastomosis, and vein patching of a tortuous segment. All other lesions were treated by graduated dilatation with an arterial dilator-shunt. All of these patients are asymptomatic presently. One patient has been operated upon recently because of symptoms related to the previously unoperated side as well as mild symptoms related to the previous operation. Two other patients with arteriographic evidence of fibromuscular dysplasia are being followed clinically. One is asymptomatic and one has minimal symptoms. Both are being treated with acetylsalicylic acid in hopes of preventing microembolization from these lesions. Important technical considerations in treating this condition are meticulous dissection of the internal carotid artery as near to the base of the skull as possible, confining the arteriotomy to the region of the carotid bulb, and straightening the carotid artery while passing the dilator under direct vision. A technique for routine shunting in these patients now is available.

Adult↗
PubMed1977

Coagulation factors influencing thrombosis of aorta-coronary bypass grafts.

Thirty patients in whom all aorta-coronary artery vein grafts became occluded within one year of operation, as demonstrated by cardiac catheterization, were evaluated for hypercoagulability. A total of 59 grafts were constructed in these patients. At operation, blood flows of 35 to 90 c.c. per minute were measured through the grafts. In 23 of the 30 patients, the blood was to be hypercoagulable, as evidenced by a low level of antithrombin III activity, high thrombin generation index, high factor VII values, or high platelet adhesivity. Another group of 11 patients (total number of grafts, 23) had all grafts patent at cardiac catheterization. These patients had flows through the grafts ranging from 20 to 125 c.c. per minute. None of the patients with patent grafts had hypercoagulable blood. The status of runoff was comparable between the patients with open grafts and those with occluded grafts.

Antithrombins↗