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Biomedical subjects

J M Duncan

Publications and source records attributed to J M Duncan.

At least 91 records · Page 5Linked to original sources
PubMed1985

Reoperation for aortic coarctation: techniques, results, and indications for various approaches.

To define the safety and efficacy of operation for recurrent thoracic aortic coarctation, we reviewed the hospital records and subsequent courses of 53 patients who underwent such procedures over a 23-year period. Previous operations included end-to-end anastomosis, prosthetic patch or subclavian flap aortoplasty, and prosthetic interposition or bypass grafts, performed in patients ranging from 1 day to 44 years old. Several different reoperative procedures were used, including an ascending-descending aortic bypass graft in 4 patients who had had two previous repairs. There were no hospital or late deaths and only 3 relatively minor complications. Only 2 patients have hypertension requiring drug therapy at follow-up, which now averages 7 years. We conclude that operative management of severe, recurrent coarctation is both safe and effective, and that several techniques of reconstruction may have a place in such therapy.

Adolescent↗
PubMed1985

Surgical experience in descending thoracic aneurysmectomy with and without adjuncts to avoid ischemia.

Over the past twelve years, surgical treatment of descending thoracic aneurysms has been performed in 360 patients. Three different operative strategies were employed during resection to provide distal aortic perfusion by temporary bypass (Group 1, 75 patients) or shunt (Group 2, 22 patients) or to simplify the operative procedure with aortic cross-clamping alone (Group 3, 263 patients). The surgical results were determined primarily by patient-related and disease-related variables. Advanced age (older than 70 years), atherosclerotic cause, and emergency operation significantly increased the risks of early mortality and morbidity. The incidence of death (11.7%), paraplegia (6.5%), or renal failure (6%) was not reduced by the use of adjunctive perfusion, and bleeding complications increased significantly in Groups 1 and 2. Spinal cord injury was increased significantly by emergency operations, cross-clamp times exceeding 30 minutes, and extensive aneurysms (p less than 0.05). The risk of renal failure was increased by advanced age and atherosclerotic cause (p less than 0.05). With an experienced surgical team, the primary risks of descending thoracic aneurysmectomy are not influenced by the method of adjunctive perfusion, but are determined by patient factors such as the nature and extent of the aneurysm.

Adolescent↗
PubMed1985

Valve failure with the Ionescu-Shiley bovine pericardial bioprosthesis: analysis of 2680 patients.

Early reports on the excellent hemodynamic function and low thromboembolic rates of the Ionescu-Shiley bovine pericardial bioprosthetic valve (BPV) encouraged us to use it as our choice for valve replacement in 2680 patients from 1978 through 1983. Analysis of these patients at 5-year follow-up (mean 21.6 months) demonstrated the following important trends. Despite anticoagulation therapy in 48%, thromboembolism occurred in 88 patients for a linearized rate of 1.87% emboli per patient-year and was not time-related. The highest incidence of thromboembolism was in mitral valve replacement (MVR) (2.76% per patient-year). The actuarial freedom from reoperation resulting from valve failure at 5 years was 82% in aortic valve replacement (AVR), 87.1% in MVR, and 92.6% in AVR/MVR. The most distressing causes for reoperation were valve calcification (33 patients, 0.68% per patient-year) and leaflet disruption (11 patients, 0.23% per patient-year). Valve calcification was related to age, small valve size, and AVR position and increased with time, especially at the 4- to 5-year intervals. In patients under 30 years of age, calcification occurred in 18.7% at a mean time of 40.8 months in AVR and in 8.2% at 44 months in MVR, for an overall rate of 11.6%. Over the age of 30 years, it occurred in 14 patients (0.6%) at a mean time of 44 months. Leaflet disruption was not related to age and occurred later in AVR (50 to 58 months) than MVR (1.5 to 61 months). Events increased with time (mean range 37 to 58 months). Because of calcification and leaflet disruption, valve failure causing reoperation has increased significantly at the 4- to 5-year intervals even when valve replacement in patients under 30 years of age is excluded. If this trend continues, the valve failure rate will be exceedingly high on further follow-up. Thus we have limited the use of the BPV to a selected group of patients in whom valve longevity is less important than effective orifice size, thromboembolic rate, and freedom from anticoagulation.

Actuarial Analysis↗
PubMed1985

Comparison of bioprosthetic and mechanical valve replacement for active endocarditis.

The choice between bioprosthetic or mechanical prosthetic valve replacement for active valvular endocarditis has been controversial. To establish the role of each, we reviewed the case histories of 185 patients who underwent valve replacement for active valvular endocarditis during the past 5 years. All patients had life-threatening, active bacterial endocarditis of a native or prosthetic valve. Group I (88 patients) had replacement with the Ionescu-Shiley pericardial valve and Group II (97 patients) with the St. Jude Medical valve. The male/female distribution, age range, and functional classification were the same in the two groups. Mean follow-up was approximately 20 months for both groups. Valve replacement was done because of native valve endocarditis in 76 patients in Group I and 49 patients in Group II. Of the remainder of the Group I patients, six had endocarditis of a bioprosthesis and six of a mechanical valve; of the remainder of Group II patients, 30 had endocarditis of a bioprosthesis and 18 of a mechanical valve. Early mortality was not significantly different between the two groups (14 deaths in each group). Of the 74 survivors in Group I, 15 underwent valve reoperation, 10 because of recurrent endocarditis and five because of sterile perivalvular leakage. The frequency of reoperation was significantly different (p less than 0.01) from that in Group II, in which only five patients underwent valve reoperation, four for recurrent endocarditis and one for sterile perivalvular leakage. The actuarial rate for freedom from reoperation was also significantly higher in Group II patients; 94.6% were free from reoperation at 4 years compared to 75% at 4 years in Group I patients (p less than 0.01). The actuarial survival rate, which also differed significantly between groups, was 78.7% at 4 years in Group I and 87.4% at 4 years in Group II (p less than 0.05). Patients receiving a bioprosthesis for active endocarditis had a significantly higher reoperation rate and a significantly greater incidence of recurrent endocarditis (p less than 0.01). Therefore, we prefer to use a mechanical valve for valve replacement in most patients who have active endocarditis.

Adolescent↗
PubMed1984

Coronary artery revascularization without cardiopulmonary bypass.

At the Texas Heart Institute between October 1969 and August 1983, there were 191 single bypass procedures performed without pump oxygenator support. These cases have been divided into two groups: Group I (160 patients) represents the time period from October 1969 through December 1981 and includes our experience with single vessel left anterior descending (LAD) coronary artery bypass without pump oxygenator support; Group II (31 patients) represents the period between January 1982 and August 1983 and includes our initial operative experience in patients with failed percutaneous transluminal coronary angioplasty (PTCA). Of 145 primary operations in Group I patients, 113 were single bypasses to the right coronary artery with a postoperative infarction rate of 3.5% (4/113). Single bypass to the left anterior descending (LAD) coronary artery in 32 patients who underwent operation early in the series was associated with a postoperative infarction rate of 18.7% (6/32) and is no longer performed without pump oxygenator support. Fifteen patients had previous coronary bypass operations and underwent single bypass without pump as a second procedure. Postoperative infarction rate in this redo group was 6.6% (1/15). Long-term follow-up data was obtained on all patients from 1 to 11 years after surgery (mean follow-up, 4 years). Four late cardiac deaths occurred at 2,3,4 and 7 years in the primary operation group (3.5%) 4/113. One late death occurred at 7 years in the redo group (6.6%) 1/15. In Group II, failed PTCA accounted for 39% of the 31 patients who underwent single right bypass without pump support; there were no perioperative infarctions and one death. Coronary bypass can be safely and effectively employed without pump oxygenator support if performed expeditiously and limited to right coronary lesions which have an adequate distal vessel. This technique has become more useful with the advent of attempted PTCA for single coronary lesions.

Journal Article↗
PubMed1984

Coronary artery bypass for unsuccessful percutaneous transluminal coronary angioplasty.

Of 518 consecutive patients undergoing percutaneous transluminal coronary angioplasty for 571 coronary lesions, 184 eventually underwent coronary artery bypass because of angioplasty failure. Delayed coronary bypass (1 week to 19 months) was done in 27 patients with no deaths. Immediate bypass was done in 87 patients with two deaths, both of which were caused by further dissection of the artery after angioplasty. Urgent bypass was required in 63 patients who were in unstable condition because of ischemia on the electrocardiogram (52 patients), unrelieved angina (57 patients), or hypotension (13 patients). There was one death in this group. In the remaining seven patients, urgent coronary bypass was done because of cardiac arrest (three deaths). Myocardial complications occurred in 23 of the 70 unstable patients, including the seven patients with cardiac arrest. There were only eight completed myocardial infarctions in the 70 unstable patients and a completed myocardial infarction rate of 11 of 184 (6.0%) overall. In the 10 patients in whom extracorporeal circulation was established within 25 minutes of myocardial insult, mortality and myocardial complications were completely avoided. The remaining patients in the urgent group were placed on cardiopulmonary bypass within 26 to 300 minutes (mean 82 minutes). Operative mortality (3.3%), completed myocardial infarction (6.0%), myocardial infarction in unstable patients (32.9%), postoperative hemorrhage (5.0%), and sternal problems (2.8%) were all significantly different from those in 3,500 consecutive coronary bypasses not following angioplasty, that were done in 1982.

Adult↗
PubMed1984

Long-term results of direct vertebral artery operations.

Arteriosclerotic occlusive disease of the vertebral arteries is common; however, vertebral artery operations are performed infrequently. From 1971 through 1983 more than 3000 cerebrovascular operations were performed; only 40 of these were direct vertebral artery operations. There were 22 women and 18 men, varying in age from 44 to 80 years (mean 61.6 years). Symptoms included dizziness or vertigo in 29 patients (73%), transient ischemic attacks in 17 (43%), syncope in eight (20%), and previous stroke in 14 (35%). Operative procedures were directed toward establishing normal antegrade vertebral flow by reimplantation (21 patients), patch graft (15 patients), or grafts (three patients). Two patients underwent bilateral procedures. There were no operative deaths. All except two patients (95%) were available for follow-up at 1 to 12 years (mean follow-up 7.75 years). There were eight late deaths from 1 to 9 years, with a 12-year actuarial survival rate of 75.8%. The eight patients who died were known to be without symptoms before death. Of the 30 survivors available for follow-up, 21 remained without symptoms, seven patients showed no improvement, two patients who had no symptoms had recurrence at 4 and 5 years, and one patient without symptoms had a stroke at 7 years. In this select group of patients with severe disease, direct vertebral artery operations have resulted in significant long-term relief of symptoms and prevention of transient ischemic attacks and strokes.

Adult↗
PubMed1983

Resection of aortic arch aneurysms: a comparison of hypothermic techniques in 60 patients.

Hypothermic circulatory arrest has been used to facilitate resection of aneurysms of the aortic arch. During a five-year period, two methods of hypothermic arrest were compared in 60 patients. In Group 1, 20 patients underwent deep hypothermia (14 degrees to 18 degrees C) and circulatory arrest to allow repair of the transverse arch under optimal conditions. A hospital mortality of 50% occurred and was attributed to uncontrolled hemorrhage and cerebral or cardiac complications. In Group 2, modified techniques were employed in 40 patients and included moderate levels of hypothermia (22 degrees to 26 degrees C) and simplified operative methods, which reduced the duration of circulatory arrest and shortened the length of perfusion. Pretreatment of plasma-soaked Dacron grafts by autoclaving eliminated serious bleeding problems. A marked improvement in patient survival (90%) and reduction in postoperative complications were observed after adoption of these modifications. The improved results in the present series have reconfirmed our belief that this type of intervention is the preferred approach to aneurysms of the aortic arch.

Adolescent↗
PubMed1983

Surgical considerations in aortitis. Part II: Mycotic aneurysms.

Mycotic aneurysms were first described as the result of nonsyphilitic bacterial infection of the arterial wall. They were often caused by septic emboli from bacterial endocarditis and were much more common prior to the era of antibiotics. Although the aorta is most often affected, such aneurysms may arise in any artery. Classified according to their etiology as primary, secondary, and cryptic mycotic aneurysms, it is imperative that immediate treatment be instituted once the diagnosis is confirmed by angiography. The patient should be placed on high doses of antibiotics appropriate for the offending pathogens. The goal of surgical treatment is the complete removal of the infected aneurysm and preservation of the distal circulation. Alternate methods of treating these lesions include the use of bypass grafts and interposition grafts. The virulence of the offending pathogen and the sensitivity to antibiotic therapy play a significant role in the success of these procedures.

Journal Article↗
PubMed1983

Surgical considerations in aortitis. Part III: Syphilitic and other forms of aortitis.

The majority of cases involving clinically significant aortitis result from Takayasu's disease, syphilis, and mycotic aneurysms, although aortitis may occur as a part of the clinical manifestation in other diseases of known and unknown etiology. Syphilitic aortitis can be treated successfully if an accurate diagnosis is made early and if appropriate antibiotic therapy is instituted. Untreated or treated inadequately, late cardiovascular complications can occur, namely, aortic aneurysm, aortic valvular insufficiency and coronary osteal stenosis. Surgical treatment should be considered when any of these late complications become manifest. Aortitis can occur with rheumatic fever and, occasionally, in rheumatoid arthritis. Giant-cell arteritis is a disease that can affect large, medium or small arteries, and usually occurs in patients over 50 years of age, chiefly women. The entire aorta may be affected. It is the only form of aortitis commonly associated with dissecting aneurysm of the aorta. Corticosteroids are effective in treating the active form of the disease and can usually prevent the development of later severe complications. Surgery is indicated when a dissecting aneurysm develops.

Journal Article↗
PubMed1983

Surgical considerations in aortitis with special emphasis on Takayasu's arteritis.

Aortitis may result in an injury to the aorta or its branches. The inflammatory process that occurs in response to the injury may ultimately result in stenosis or occlusion from fibrosis and dilatation or aneurysm formation from destruction and weakening of the arterial wall. As a result of antibiotics, some diseases known to cause arteritis have declined over the years (most notably syphilis and rheumatic fever). Other systemic diseases not initially thought to have vascular involvement have also been found to be associated with widespread arteritis. All forms of this entity are capable of producing dilatation or aneurysm formation, but only Takayasu's arteritis can produce narrowing or occlusion of the aorta or its branches, with the rare exception of stenosing arteritis, which sometimes follows radiation therapy in childhood. In Takayasu's arteritis, any segment of the aorta, as well as the pulmonary arteries, may be affected. This disease is divided into four types, depending on the location and extent of the arteritis. In Type I, the disease is limited to the aortic arch and its branches. In Type II, the vascular lesions are confined to the descending thoracic and abdominal aorta without involvement of the aortic arch. Type III is mixed, containing features of Types I and II. Type IV is characterized by dilatation and aneurysm formation in the affected vessels and may have pulmonary artery involvement. The four types are described, with their clinical manifestations, diagnosis, and surgical treatment.

Journal Article↗
PubMed1983

The St. Jude medical valve: early clinical results in 253 patients.

The St. Jude Medical cardiac valve is a low-profile, bileaflet, central-flow prosthesis made entirely of pyrolytic carbon. A total of 261 St. Jude valves were implanted in 253 patients during a 25-month period. Perioperative mortality for the entire series was 9.1%, including patients undergoing reoperation for valve disease and those having associated cardiac procedures. There were four nonfatal thromboembolic episodes during the follow-up period, resulting in a risk of thromboembolism for aortic and mitral valves of 2.1% and 2.1% per patient year, respectively. There were no instances of structural failure of the valve, and no valve-related hemolysis occurred. Two-year actuarial survival was 95%. Hemodynamic studies indicate that the valve has the lowest transvalvular pressure gradient of any prosthetic mechanical valve available, and we believe it is the valve of choice for patients in whom a prosthetic mechanical valve is indicated.

Journal Article↗
PubMed1983

Early experience with the ionescu-shiley pericardial xenograft valve. Accelerated calcification in children.

Recognizing the problems of thromboembolism and anticoagulation in children and the high incidence of calcification in porcine valves in children, we hoped that the Ionescu-Shiley valve might be a good choice in the younger age group. We implanted 2,372 Ionescu-Shiley valves in 2,167 patients between 1978 and 1982, of which 30 were in children 16 years of age and younger. Although there have been no known instances of thromboembolism, valve infection, or valve disruption in this group of children, seven (23%) have already required reoperation for calcific stenosis. Although calcification appears maximal in postpubertal children less than 17 years of age, we consider it unwise currently to place these valves in any child and have returned to mechanical valves for this purpose.

Adolescent↗
PubMed1982

Early degeneration of porcine xenograft valves in pediatric patients who have undergone apico-aortic bypass.

The glutaraldehyde-preserved stented porcine xenograft valve has been durable in adult patients with a low incidence of valve-related complications. In children, however, early degeneration and calcification of this valve is now being reported. The etiology of the early degeneration is still unclear but may be related to calcium metabolism, tissue fatigue, and host rejection. During the last 5 years at the Texas Heart Institute, 21 patients under 23 years of age underwent implantation of an apico-aortic conduit containing a porcine xenograft valve for treatment of severe forms of left ventricular outflow tract obstruction. Because of early failure, the valve was replaced in two patients (11.5%) within 3 years of implantation. Although early degeneration of the porcine valve might occur in some children, it may still be the preferred valve to use in young patients because anticoagulation is not required with its use.

Journal Article↗
PubMed1982

Acute limb ischemia from sudden thrombosis of an abdominal aortic aneurysm: a case report.

Thrombosis of a previously undiagnosed aneurysm of the abdominal aorta in a 64-year-old woman resulted in acute and severe ischemia in both legs. Prompt surgical resection of the aneurysm and restoration of aortic continuity with a fabric graft brought about complete resolution of her symptoms, with excellent functional results one year after the operation.

Journal Article↗
PubMed1982

Improved cardiac function following left ventricular aneurysm resection: pre- and postoperative performance studies in 150 patients.

One hundred fifty patients underwent radionuclide left ventricular performance studies before and one week after resection of a left ventricular aneurysm. The patients were classified according to pre-and postoperative ejection fraction into five classes as follows: Class I > 50%, Class II = 41%-50%, Class III = 31%-40%, Class IV = 21%-30%, and Class V = < 21%. They were also classified into groups according to the size of the aneurysm and wall thickness. Operative mortality was 4.6% (7/150). One hundred one patients (67%) improved at least one "ejection-fraction class" postoperatively; whereas in a similar group of patients who underwent aortocoronary bypass without left ventricular aneurysm resection, only 42.3% (58/137) improved (p <.01). Preoperatively, ejection fraction was < 40% in 136 patients (90.6%); and postoperatively, it was > 40% in 59 patients (39.3%) (p <.01). Improvement of at least one "ejection-fraction class" occurred in 22 patients (47.8%) with small aneurysms, 54 patients (69.2%) with moderate size aneurysms (p <.05), and 25 patients (96.1%) with large aneurysms (p <.01). Sixty-nine patients (88.4%) with thin-walled aneurysms and 32 patients (44.4%) with thick-walled aneurysms improved (p <.01). Resection of a left ventricular aneurysm improves left ventricular function, particularly in patients with large, thin-walled aneurysms. A less aggressive surgical approach is warranted when dealing with thick-walled akinetic areas as patients with these lesions do not respond well to resection.

Journal Article↗
PubMed1982

Open aortic anastomosis: improved results in the treatment of aneurysms of the aortic arch.

Over a 7-month period, 15 consecutive patients underwent resection and reconstruction of the transverse aortic arch for a variety of pathologic lesions using moderate systemic hypothermia (24 degrees C) and brief circulatory arrest. Simplified surgical techniques were developed to allow rapid repair. The "open" aortic technique facilitated repair of arch aneurysms, aortic dissections and obstructive lesions of the arch tributaries. The mean cerebral ischemic time was 11.2 +/- 1.5 minutes (mean +/- SEM). Moderate hypothermia afforded adequate cerebral and myocardial protection during circulatory arrest and shortened the duration of extracorporeal bypass necessary for the cooling and rewarming phases (87 +/- 8 minutes). Dacron grafts preclotted by a new method greatly reduced postoperative blood loss. Since these simplified techniques were adopted, 14 patients (93%) have survived aortic arch replacement, with minimal postoperative morbidity. One patients with severe preoperative left ventricular dysfunction died of cardiac failure after operation. These results suggest that aortic arch replacement can be performed safely and with low operative risk.

Aorta, Thoracic↗