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Biomedical subjects

H T Bahnson

Publications and source records attributed to H T Bahnson.

At least 73 records · Page 4Linked to original sources
PubMed1979

Expanded microporous polytetrafluoroethylene as a vascular substitute: a two year follow-up.

Since 1974, 131 femoropopliteal, distal popliteal, and tibial bypasses have been performed using expanded microporous polytetrafluoroethylene (PTFE). Forty patients were operated on for limb salvage, and 21 had had previous bypass procedures. The overall patency rate was 82%. Early occlusions possibly were related to technical error, but most probably were due to severity of disease and poor runoff. Late occlusions were related to progressive atherosclerosis in the proximal or distal arterial tree. A 75.7% cumulative patency rate was noted at 28 months. In man the PTFE prosthesis demonstrates a smooth intimal lining with fibroblastic ingrowth into the interstices of the graft. These results are considered to be excellent in this high-risk patient population. The patency rates achieved with PTFE are better than those accomplished with alternative conduits and approach the patency rates reported with autogenous saphenous vein. Expanded microporous polytetrafluoroethylene with its high patency, pliability, and tissue incorporation is an excellent arterial substitute. Only with continued use of this material and a more uniform patient selection can more equitable comparisons be made between expanded PTFE and the autogenous vein.

Adult↗
PubMed1979

Arteriovenous ECMO for neonatal respiratory support. A study in perigestational lambs.

A study was undertaken to investigate the applicability of the arteriovenous mode of perfusion for partial support of neonatal respiration. Perigestational lambs, delivered by cesarean section, served as the animal model of respiratory distress. Arteriovenous flow was accomplished between a single umbilical artery and vein. A microchannel membrane oxygenator was used to provide partial respiratory support to the newborn lambs. Total systemic flow, pulmonary blood flow, and pulmonary vascular resistance were assessed at various rates of arteriovenous perfusion and correlated with systemic oxygenation. A reduction in right-to-left shunting of blood and pulmonary vascular resistance occurred as arterial oxygenation rose from conditions of hypoxemia to PaO2 values higher than 50 torr. Myocardial performance was not impaired at rates of arteriovenous perfusion below 30 percent of the total systemic flow, as evidenced by normal electrocardiographic tracings, pulmonary capillary wedge pressures, and central venous pressures. Arteriovenous extracorporeal membrane oxgenation (ECMO) may be particularly suitable for use in infants with hypoxia and high pulmonary vascular resistance.

Animals↗
PubMed1979

Extra-anatomic bypass with expanded polytetrafluoroethylene.

Expanded polytetrafluoroethylene has been used successfully for femoropopliteal bypass, aortopulmonary bypass and as a venous substitute. Thirteen patients with impending limb loss had extra-anatomic bypasses with expanded polytetrafluoroethylene. Five patients with unilateral iliac disease had femorofemoral bypass for impending limb loss, and five debilitated patients underwent axillofemoral and bifemoral bypass for limb salvage. Nine of ten patients had salvage of the extremities. Three patients had extended profundoplasty, two combined with polytetrafluoroethylene femoropopliteal bypass to isolated popliteal artery segments. Two of these patients had limb salvage. The patency rate is 92 per cent, and the limb salvage rate is 85 per cent in this difficult group of patients. The follow-up period extends to 28 months, and 12 patients are beyond one year. In six patients, polytetrafluoroethylene carotid subclavian bypass was performed for the subclavian steal syndrome; all patients had relief of the symptoms. One patient underwent axillary-axillary bypass with excellent results. Expanded microporous polytetrafluoroethylene with its high patency, shortened operating time, biocompatibility and excellent tissue incorporation is an excellent arterial substitute. The pliability and no requirement for preclotting make polytetrafluoroethylene ideally suited for patch angioplasty and suturing in areas difficult to expose.

Adult↗
PubMed1978

Selected therapy for ascending aortic aneurysms.

Since 1971, ten patients, 26 to 62 years of age, have undergone repair of ascending aortic aneurysms with concomitant aortic insufficiency. Three patients had Marfan's syndrome, five patients had cystic medial necrosis, one had leutic aortitis, and one had atherosclerotic involvement of the aorta. There was one operative death. Follow-up exceeds seven years. Because of the tendency for progressive annular and sinus dilation in Marfan's syndrome, composite graft and valve conduits with reimplantation of the coronary arteries is the procedure of choice. In selected patients with annulaortic ectasia, good valve tissue and no sinus dilation, bicuspidization of the valve, and replacement of the ascending aorta is indicated. The operation is generally less formidable than composite graft replacement, maintains normal coronary anatomy, and alleviates the long-term risks of anticoagulation.

Adult↗
PubMed1978

Delayed postoperative cardiac tamponade: diagnosis and management.

Symptoms and signs of decreased cardiac output associated with an elevated venous pressure should alert one to the possibility of delayed cardiac tamponade. Enlargement of the cardiothoracic ratio shown by serial roentgenograms and demonstration of significant pericardial effusion by echocardiogram or radionuclide angiocardiography support the diagnosis. Erratic response of the prothrombin time to administration of warfarin and abnormal results of liver function test are additional clues to its diagnosis. Right heart catheterization documents the presence of tamponade and excludes other diagnostic considerations. Operative decompression of the pericardial space can be accomplished by pericardicentesis, subxiphoid pericardiotomy, median sternotomy, or thoracotomy. Hemodynamic observations following the relief of tamponade assure that an adequate therapeutic procedure has been performed.

Adult↗
PubMed1977

Discrete subvalvular aortic stenosis. An evaluation of operative therapy.

Angiocardiographic and operative observations support the validity of classifying the spectrum of congenital subvalvular aortic stenosis into a membrane, fibromuscular collar, and tunnel. Our current operative method is to excise a thin membrane or thick fibrous ridge, and, if a fibromuscular collar or tunnel is identified, to effect a left ventricular myomectomy as described by Morrow for hypertrophic subaortic stenosis. Data from experience with 35 children indicate that this approach is effective and safe. Gradients are substantially reduced and residual obstruction acceptable. Successive clinical evaluations (100 percent of 33 survivors) over an interval of 1 to 13 years (mean of 6) affirm that amelioration of the obstruction endures.

Angiocardiography↗
PubMed1977

Traumatic false aneurysm and arteriovenous fistula of the profunda femoris artery: surgical management and review of the literature.

Successful surgical repair of a false aneurysm and an arteriovenous fistula of the deep femoral vessels has been achieved 8 years after the initial injury. A review of the literature disclosed 20 other similar cases from military and civilian practice; ligation of the artery was utilized 14 times with generally poor results when long-term follow-up was available. Most vascular wounds were due to fragments, as was the case in our patient, and involvement of the deep femoral vessels was recognized more frequently in delayed complications than in acute injuries. Ten cases of false aneurysm of the deep femoral artery without arteriovenous fistula have been found to be associated with fracture or orthopedic precedures. Mild intravascular hemolysis was present in our patient and was corrected promptly after operation. Only one other such case was found in the literature. The profunda femoris artery, which was dilated and elongated, resumed a normal caliber in its proximal segment on arteriography performed one year after the operation. Preservation of the deep femoral artery may be of significance for a good clinical result in the treatment of arteriovenous fistulas and is of special interest in view of its potential importance in reconstructive procedures for atherosclerotic occlusive disease. Early diagnosis and treatment of arteriovenous fistulas for the prevention of hemodynamic, systemic, and structural changes in the vessel wall are advocated.

Adult↗
PubMed1977

Valve replacement in children and adolescents.

Replacement of diseased heart valves has become the treatment of choice in many adults. Valve replacement in older children and adolescents has been done in our institution only when other procedures are ineffective. Over the past 10 years, 24 patients have received 28 artificial valves. Thirteen (54 per cent) had rheumatic heart disease; the remainder had congenital or acquired valvular abnormalities. The Björk-Shiley valve was most commonly used in the aortic position and the Beall prosthesis in the mitral position. Sixteen patients (67 per cent) survived operation and have been followed from 3 to 79 months, averaging 27 months. All are free of cardiac symptoms. Hemarthrosis occurred once in 2 survivors (13 per cent). Eight patients died (33 per cent), 5 immediately postoperatively and 3 within a year after the operation. The mortality rate has declined to 21 percent during the past 3 years. Our experience in the pediatric age group suggests that valve replacement is a serious undertaking with higher mortality rate than in adults. The operation should be reserved for those patients in whom valvuloplasty or valvulotomy is expected to be ineffective.

Adolescent↗
PubMed1977

Management of bilateral ductus arteriosus in complex cyanotic heart disease.

Bilateral ductus arteriosus (BDA) usually is associated with complex cyanotic heart disease. Since pulmonary valve atresia often is part of the complex, hypoxia may necessitate emergency cardiac catheterization and surgery for these critically ill newborn infants. Optimum management depends on accurate delineation of the intracardiac and great vessel anatomy. Since the ductus arteriosus has a tendency to close spontaneously, the true anatomy of the fourth to sixth aortic arch connections should be determined on the first catheterization. An over-all plan for future care by the medical-surgical team should have been made at the time of the initial surgical procedure. The case histories of four newborn infants with BDA associated with cyanotic heart diseases are reported. The anatomy and basic embryology of the fourth to sixth arch system is reviewed and recommendations for long-term management are given.

Aorta, Thoracic↗
PubMed1976

Surgical treatment of acute aortic regurgitation in infective endocarditis.

During a six-year period 15 consecutive patients with isolated aortic regurgitation due to infective endocarditis were encountered. None had prior significant aortic valve disease. Elective valve replacement was performed in 13 patients; emergency operation was needed in only 1 patient because of intractable pulmonary edema. One patient died suddenly from acute heart block while undergoing medical treatment. Preoperative cardiac catheterization studies in 10 of the 14 patients revealed gross elevations of left ventricular end-diastolic pressure, pulmonary hypertension, depressed cardiac output, and 3 to 4+ aortic regurgitation. There was 1 early and 1 late postoperative death, both due to systemic embolism, yielding an overall surgical mortality of 14%. After a mean follow-up of 18 months, 10 of the 11 patients are in New York Heart Association Functional Class I. Most patients with acute aortic regurgitation secondary to infective endocarditis have clinically observable congestive heart failure and will eventually require valve replacement. If congestive heart failure can be stabilized by a medical regimen, a course of antibiotic therapy can be administered and elective valve replacement can be performed. The time taken for preoperative antibiotic treatment is not associated with irreversible myocardial damage sufficient to influence the results of operation.

Adolescent↗
PubMed1976

Double-outlet right ventricle with tunnel from left ventricle to aorta.

The successful surgical correction of an unusual form of double-outlet right ventricle (DORV) in a 4-year-old boy is described. A long tunnel-like structure was present between the left ventricle and the aorta and also communicated with the right ventricle. hemodynamic and angiographic evaluation demonstrated restrictive communications between the tunnel, the aorta, and each of the ventricles. A pathological concept explaining the anatomic abnormality seen in this patient is discussed.

Cardiac Catheterization↗
PubMed1976

The use of expanded microporous polytetrafluoroethylene for limb salvage: a preliminary report.

Initial laboratory and clinical evaluations of a new prosthetic material, expanded microporous polytetrafluoroethylene (PTFE), for small vessel replacement is promising and encourages further clinical trial. Frequently the autogenous saphenous vein is not available for bypass procedures, and alternative arterial substitutes have not proved reliable for replacement of small vessels. In this study, 15 patients with impending loss of limb and no available saphenous vein underwent revascularization of the lower extremity with expanded microporous PTFE grafts. Thirteen of 15 patients now demonstrate viable extremities with a resulting over-all early patency and limb salvage rate of 87 percent for this series. Follow-up ranges from one to 8 months. Seven patients had diabetes mellitus and eight had atherosclerotic heart disease. Nine grafts crossed the knee joint. In all patients arterial runoff was poor. Six patients had previous femoropopliteal bypasses, five with autogenous veins and one with Dacron velour. Two patients had multiple previous operations that failed, first with autogenous vein and later with fabric grafts. The current limb salvage and patency rate of 87 percent in high-risk patients suggests that expanded PTFE may be the prosthesis of choice when an autogenous vein is not available and possibly an equally good substitute when the venous autograft is available.

Aged↗
PubMed1975

Surgical treatment of atrioventricular canal defect.

Fifty-nine patients with congenital anomalies of the atrioventricular canal underwent operation and all survivors were followed up. In 42 patients with partial atrioventricular canal defects, ten had preoperative congestive heart failure. Three, or 7.1%, died of endomyocardial fibroelastosis, high pulmonary vascular resistance, and severe mitral regurgitation. A fourth patient later died of Wolff-Parkinson-White syndrome and fibrilation. Reoperations in five patients were all successful. No patients had persistent atrioventricular blocks, and all patients are asymptomatic. Two of these subjects continue to receive digoxin therapy, and one of them is believed to have substantial mitral insufficiency. Of the 17 patients who had complete atrioventricular canal defects, 13 had a divided common anterior leaflet attached to the septum by chordae tendineae, and four had undivided and unattached anterior leaflets. Two had previously undergone pulmonary banding, and nine were treated for congestive heart failure. Six died after operation. There were no reoperations. No patient presently has required a pacemaker. Two subjects have persistent cardiomegaly.

Adolescent↗