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Biomedical subjects

V A Fahey

Publications and source records attributed to V A Fahey.

13 recordsLinked to original sources

Extraanatomic bypass surgery.

The term "extraanatomic bypass" applies to grafts that pass through a different anatomic pathway than do the natural blood vessels they replace. These grafts are devised to circumvent complex problems when conventional vascular procedures are not possible or are too hazardous to perform. There are various indications, advantages, and disadvantages to each of these grafts. Extraanatomic bypass grafts are an accepted technique with known patency rates. Quality nursing care plays a significant role in successful patient outcome.

Blood Vessel Prosthesis Implantation↗

Heparin-induced thrombocytopenia.

Heparin is one of the most frequently prescribed medications in the United States with more than 1 trillion units being used each year. However, some patients who receive heparin may have development of a rare but severe complication called heparin-induced thrombocytopenia, which is associated with significant morbidity and mortality rates. This syndrome is a clinical event in which the use of heparin results in thrombocytopenia, venous or arterial thrombosis, and, less commonly, bleeding. The exact mechanism of heparin-induced thrombocytopenia is not clearly understood, but an immune-mediated response to heparin resulting in platelet consumption is the most widely accepted theory. The main treatment is discontinuation of heparin therapy; however, alternative treatments are discussed. The critical role nurses play in the early detection and prevention of the complications of heparin-induced thrombocytopenia is addressed. Assessment of all patients receiving any form of heparin therapy is emphasized.

Anticoagulants↗

Improved long-term patency of infragenicular polytetrafluoroethylene grafts.

This article reviews late graft patency and the incidence of postoperative complications in 75 infragenicular polytetrafluoroethylene bypass grafts (20 posterior tibial, 26 anterior tibial, and 29 peroneal). All patients received a heparin infusion after operation and were switched to warfarin before discharge to maintain coagulation parameters (prothrombin time and partial thromboplastin time) approximately twice that of control subjects. Primary procedures were done in 14 patients (19%), and the remaining patients had one or more previous procedures. Ninety-seven percent of patients had limb-threatening ischemia. Graft patency was confirmed by interval examinations and Doppler ankle pressure measurements. The mean follow-up was 36 months, and long-term graft patency (4 years) was determined by life-table analysis. The 2-year cumulative patency rate for this group was 45% and the 4-year patency rate was 37%. The latter is significantly better than the patency rates of 12% reported for similar untreated randomized grafts. Anticoagulation was subtherapeutic in 15 patients at the time of graft thrombosis, and if these were excluded, the 2- and 4-year patency rates were 58% and 50%, respectively. Hematomas requiring drainage occurred in 10 patients (13.3%) and six patients (8%) developed wound infections, but graft infection occurred in only two patients. Two patients (2.6%) developed late bleeding complications necessitating cessation of the warfarin. There was one fatal perioperative myocardial infarction (1.3%) and four late deaths, none of which were related to the warfarin therapy. Although the incidence of postoperative hematoma and wound infection was increased, late complications occurred infrequently.(ABSTRACT TRUNCATED AT 250 WORDS)

Amputation, Surgical↗

The reoperative potential of infrainguinal bypass: long-term limb and patient survival.

The present study reviews the fate of patients undergoing reoperation after failure of infrainguinal bypass grafts. During a 10-year period, 202 patients with failed distal bypass grafts had 389 infrainguinal reoperative procedures, an average of 1.9 reoperations per patient. Including the initial procedure and subsequent reoperations, a total of 591 operations were performed in this group. Secondary bypass was performed in 101 patients, a tertiary procedure in 51, a fourth bypass in 30, and more than four operations were required in 20 patients. Reoperation was performed to treat severe ischemia (rest pain, ulceration, or gangrene) in 377 of 389 cases (97%). Repetitive bypass was performed with autogenous vein in 21 cases (7.4%), composite grafts in 16 patients (5.6%), and polytetrafluoroethylene in 247 cases (87%). The remaining 105 reoperations were thrombectomy in 77 cases, thrombectomy plus distal angioplasty in 20 cases, and profundaplasty in eight cases. The distal anastomosis was to the popliteal artery in 14% of reoperative cases and to the tibial or peroneal artery in 59%. Mean follow-up for all patients was 70 months. Four operative deaths occurred in 389 reoperations (1.0%), and there were 35 late deaths. The cumulative life-table 5-year survival rate for all patients was 80%. The operative morbidity rate was 12.3%, including wound infection in 3.1% and hematoma in 6.4%. Sixty-seven cases required major amputation, below-knee in 48 (72%) and above-knee in 19 (28%). The 5-year limb salvage rate was 59%. Cumulative graft patency was 37% at 5 years. The 80% 5-year survival rate may reflect aggressive management of associated carotid and coronary artery disease. The demonstrated long survival indicates that recurrent ischemia after distal bypass failure requires attention. In this study, re-operation provided long-term limb salvage in most cases without significant compromise in patient safety or amputation level if amputation was required.

Amputation, Surgical↗

Venous reconstruction. Surgery for severe venous stasis.

Deep venous thrombosis is a common occurrence among hospitalized patients. The sequelae of deep venous thrombosis, chronic venous insufficiency are well known. The nurse must know the signs and symptoms of venous thrombosis, and have knowledge of patients at high risk for developing thrombosis. Careful attention must also be given to accurate diagnosis of the precise venous abnormality prior to surgical intervention. New techniques, such as valve transplantation, plastic reconstruction of existing valves, or insertion of prosthetic valves, are in the early investigative stages. It is evident from the statistics mentioned earlier that the need for venous reconstructive surgery is widespread.

Blood Vessel Prosthesis↗

Sequential changes in coagulation and platelet function following femorotibial bypass.

Twenty-four patients who received no antiplatelet medications and underwent femorotibial bypass grafting (nine vein, 12 polytetrafluoroethylene [PTFE], and three composite PTFE-vein) had serial measurements taken of their platelet function and coagulation. The concentration of collagen required to produce half-maximal platelet aggregation (Kd), the platelet aggregation ratio, antithrombin III, factor VIII-related antigen, and fibrinolytic activity (platelet-rich plasma) was measured preoperatively and 3 and 7 days after surgery. Before surgery eight patients exhibited an increase of platelet reactivity to collagen. Following femorotibial bypass grafting, the mean preoperative Kd of 0.52 +/- 0.37 microgram/ml fell to 0.34 +/- 0.35 microgram/ml on the third postoperative day (P less than 0.001) and returned to 0.41 +/- 0.72 microgram/ml on day 7. Factor VIII-related antigen increased from a mean preoperative value of 248 +/- 29% of normal activity to a mean of 360 +/- 96% on postoperative day 3 (p less than 0.01) and further increased to 428 +/- 78% on day 7 (p less than 0.01). Fourteen patients had antithrombin III measurements taken, and their levels also fell on the third postoperative day (110 +/- 5.7% to 71 +/- 6.5%; p less than 0.001). No significant changes in fibrinolytic activity were noted. Persistent platelet reactivity was found in seven patients beyond the seventh postoperative day. After administration of 325 mg of aspirin, the abnormal platelet reactivity ceased. Increased platelet reactivity to collagen, factor VIII-related antigen, and a decrease in the antithrombin III level are indicative of a hypercoagulable state in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens↗

Antithrombin III deficiency as a reflection of dynamic protein metabolism in patients undergoing vascular reconstruction.

Antithrombin III (AT-III) deficiency has been associated with increased risk of venous and arterial thromboses and arterial graft failure. Deficiency of this circulating glycoprotein may be congenital; however, acquired deficiencies may develop in protein-losing or protein-wasting states. In the present study, AT-III levels of 108 patients undergoing vascular surgical procedures were determined preoperatively and at intervals (third, fifth, and seventh days) postoperatively. The mean AT-III level was then compared to the patient's protein status. The effect of reduced AT-III activity on early graft failure was also noted. A low preoperative AT-III level (less than 80%) was found in 16.3% of the patients studied. Among 83 patients with serum albumin levels greater than 3.0 gm/dl or transferrin levels greater than 180 mg/dl, reduced AT-III activity was present in only 10 (12%). In contrast, when serum albumin levels were less than 3.0 gm/dl, AT-III deficiency was found in 12 of 25 patients (48%) (p less than 0.01). Early thrombosis of a femorodistal graft occurred in 5 of 15 patients (33%) with reduced AT-III levels. When AT-III levels were normal, early bypass failure occurred in only 9 of 67 grafts (13.4%). However, this difference was not statistically significant. An additional 15 patients had sequential pre- and postoperative measurements (up to 3 weeks) of serum protein and AT-III levels to illustrate the relationship between the dynamics of protein metabolism and AT-III levels. There was a clear temporal relationship between albumin, transferrin, and AT-III levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗