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Biomedical subjects

J M Duncan

Publications and source records attributed to J M Duncan.

At least 73 records · Page 4Linked to original sources
PubMed1988

Complications in cardiac transplant patients requiring general surgery.

With the advent of cyclosporine A, heart transplantation has become a widely accepted treatment for patients with end-stage cardiac disease that is not amenable to medical or surgical treatment. Between July 1982 and December 1985, 86 heart transplantations were performed at the Texas Heart Institute with cyclosporine A and prednisone used for immunosuppression. Thirty patients had complications requiring general surgical consultation. The pancreas and biliary tracts were most commonly affected. Pancreatitis developed in sixteen patients; five patients required operative intervention, resulting in a 40% mortality rate. Five of nine patients with cholecystitis required cholecystectomy. All patients survived the procedures. Other gastrointestinal complications included colonic ileus, bowel perforation, gastrointestinal bleeding, gastric outlet obstruction, and perirectal abscess. Patients who have undergone cardiac transplantation are susceptible to life-threatening infections and are at risk of serious complications requiring general surgical intervention. Better results can be obtained in these complex clinical situations when complications are identified early and managed aggressively through the adjustment of immunosuppression, adequate selection of antimicrobial agents, and proper timing of surgical intervention.

Cholecystitis↗
PubMed1988

Cyclosporine A pharmacokinetics in a cardiac allograft recipient with a jejuno-ileal bypass.

A 41-year-old man with a 13-year history of JI bypass for morbid obesity developed idiopathic cardiomyopathy. A pretransplant CsA pharmacokinetic profile demonstrated inadequate PO absorption with no appreciable enterohepatic recirculation. Inadequate levels occurred after three hours and became undetectable after 18 hours. The patient's status did not permit JI bypass reversal before transplantation. IV CsA was administered before cardiac transplantation, and a continuous IV CsA infusion was maintained for 72 days through episodes of CMV reactivation infection and complications common to the immunosuppressed patient. JI bypass reversal was subsequently performed and IV CsA converted to oral form as intestinal function improved. A repeat PO CsA pharmacokinetic profile demonstrated a threefold rise in peak concentration, delayed smaller peak concentrations representing enterohepatic recirculation, and a steady-state blood level that persisted for 23 hours. We have found that pretransplant CsA pharmacokinetic analysis predicts CsA bioavailability and serves as a guide for achieving optimal CsA serum concentrations; adequate PO absorption and enterohepatic recirculation of CsA depends on the anatomical and functional integrity of the jejunum and ileum; continuous IV CsA infusion can be precisely adjusted for optimal therapeutic efficiency; and long-term CsA infusion can benefit critically ill transplant patients without increased morbidity.

Adult↗
PubMed1987

Reconstruction of coronary artery anomaly in an infant using the internal mammary artery: 10-year follow-up.

We report a case of tetralogy of Fallot with an unsuspected anomalous left anterior descending coronary artery arising from the right coronary artery and crossing the right ventricular outflow tract in a 16-month-old infant. During operation, the anomalous artery was severed. Successful repair of the intracardiac anomalies was performed, including left anterior descending-internal mammary artery reconstruction of the anomalous artery. This case illustrates the importance of delineation of coronary artery anatomy and even selective coronary arteriography in patients with tetralogy of Fallot, since anomalous coronary arteries occur most frequently in association with other cardiac anomalies. Arteriography 10 years later revealed a patent anastomosis to the left anterior descending artery, proving the durability of the internal mammary artery in a patient we believe to be the youngest to have undergone bypass with this particular conduit.

Angiography↗
PubMed1987

The management of aortoduodenal fistula by in situ replacement of the infected abdominal aortic graft.

Conventional surgical wisdom dictates the complete removal of infected abdominal aortic graft, oversewing of the aorta, and restoration of lower limb bloodflow by extra-anatomic bypass grafting. Dissatisfied with this approach because of the high incidence of local complications, mortality, and loss of limb, 20 patients with secondary aortoduodenal fistula had duodenal repair, excision of the old graft, and placement of a new graft in the same location. A similar technique was used in three patients with erosion of an aortic graft into the jejunum. Length of follow-up averaged 5.2 years, and was more than 1 year in each instance. Of the eighteen patients who survived the repair, three have had early recurrent rupture or false aneurysm of the proximal aortic anastomosis, with consequent death in two, but fifteen patients (83%) have had no further related problem. There was no loss of limb. Use of greater omentum as a protective barrier seemed helpful. Optimal antibiotic usage, and the idea that varying degrees of graft infection require different approaches, require further definition. In conclusion, in situ graft replacement is the correct operative strategy in this challenging group of patients.

Aorta, Abdominal↗
PubMed1987

Early experience with a new PTFE graft below the inguinal ligament.

Between July 1984 and July 1985, 65 expanded polytetrafluoroethylene grafts (Vitagraft) were implanted in the infrainguinal position in 51 patients, including 41 men and 10 women, with an average age of 63 years. The indications for surgery were severe claudication (36 grafts) or ischemic necrosis of the extremities (29 grafts). Thirteen of the patients (25%) had had a previously placed infrainguinal graft of another type that had failed, requiring reoperation. Proximal vascular reconstruction (consisting of ten aorto-femoral and two femoro-femoral bypasses) was performed in 12 patients who had 16 grafts. Simultaneous aortocoronary bypass surgery was done in conjunction with a femoral-popliteal bypass in six patients. The site of distal anastomosis was the suprageniculate popliteal artery in 21 grafts (32%), the infrageniculate popliteal artery in 33 grafts (51%), tibio-peroneal trunk in seven grafts (11%), and the posterior tibial artery in four grafts (6%). The mean follow-up was 9.6 months (range, 1 to 16 months). Two grafts (3.0%) failed early (< 30 days). Another three grafts (4.6%) occluded between 1 and 6 months postoperatively, and five occluded after 6 months. The cumulative patency rate at 15 months was 78.8%. Limb salvage was not possible in three patients, who underwent amputation because of multiple previous operations and a lack of distal run-off. There were no operative deaths, graft infections, aneurysms, or untoward reactions (including seromas) along the graft tracts. At this early follow-up date, we have not encountered the complications normally associated with other grafts; our early results indicate that continued clinical use is warranted.

Journal Article↗
PubMed1987

Aortic aneurysms.

Explore the source record for details and available documents.

Aortic Dissection↗
PubMed1986

Magnetically retained implant denture.

This technique offers the following advantages: The disks allow the castings to be placed with a minimum amount of torque or tension. The casting can be removed from the frame for cleaning at scheduled appointments. Removal of the casting permits evaluation of the fixation of each implant.

Dental Implantation, Endosseous↗
PubMed1986

Durability and low thrombogenicity of the St. Jude Medical valve at 5-year follow-up.

Between November, 1978, and December, 1983, 736 patients had valve replacement with the St. Jude Medical valve prosthesis. There were 478 patients with aortic valve replacement (AVR), 188 with mitral valve replacement (MVR), 63 with double valve replacement, and 7 with tricuspid valve replacement (they were not included in this study). The mean age at the time of operation was 46.7 years for patients having AVR and 48.6 years for those having MVR and AVR + MVR. Follow-up totaled 1,116 patient-years (range, 4 to 82 months). Early (30-day) mortality was lowest for isolated MVR (2.3%) and AVR (3.7%), and increased with reoperation or when associated procedures were combined with valve replacement. Patients undergoing reoperation or having associated procedures made up 49% of the AVR and 54% of the MVR groups. All patients were advised of the need for long-term anticoagulation with warfarin sodium. Nine patients (7 with AVR, 1 with MVR, 1 with AVR + MVR) had suspected or confirmed episodes of systemic thromboembolism, a linearized incidence of 0.99% per patient-year for AVR, 0.36% per patient-year for MVR, and 0.98% per patient-year for AVR + MVR. Eight patients with AVR underwent reoperation for prosthetic valve endocarditis (5 of the 8 patients had endocarditis prior to initial valve replacement). There were no instances of structural valve failure. There were 37 late deaths. Actuarial survival at 5 years (excluding early mortality, 95% confidence limits) was 89.8% for AVR, 84.8% for MVR, and 95.2% for AVR + MVR.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1986

Addition of papaverine to cardioplegia does not reduce myocardial necrosis.

In a randomized, double-blind prospective study involving 495 patients, we investigated whether the addition of papaverine, 60 mg, to our existing regimen of cold cardioplegia would reduce myocardial necrosis during elective coronary artery bypass operations. Twenty-one (4.2%) patients sustained acute postoperative myocardial infarctions (MI), and 7 (1.4%) died during hospitalization. Neither MI nor death was related to papaverine supplementation. Among 469 patients without postoperative MI, levels of the myocardial-specific isoenzyme of creatine phosphokinase measured 10 hours after aortic cross-clamping were related to ischemic cross-clamp time, but not to papaverine supplementation of cardioplegia. At declamping after completion of distal anastomoses, ventricular fibrillation was more common after cardioplegia without papaverine (32% versus 9%). No other differences between the two groups were found in intraoperative and postoperative hemodynamics, difficulty of weaning from bypass, or postoperative volume requirements. We identified three risk factors for postoperative MI: ECG evidence of new ischemia prior to bypass, unusual technical difficulty with distal anastomoses for the surgeon, and prolonged time of ischemia. We conclude that addition of papaverine to our cardioplegia regimen did not affect outcome or nonspecific myocardial necrosis.

Clinical Trials as Topic↗
PubMed1986

The effect of coronary bypass on the outcome of peripheral vascular operations in 1093 patients.

One of the greatest risks in peripheral vascular operations is the presence of significant coronary artery disease. To assess the proper timing and demonstrate a possible protective effect of coronary artery bypass (CAB), 1093 patients who underwent one or more peripheral vascular operations in addition to CAB from 1976 through 1984 were analyzed. During that same period, 24,441 patients underwent CAB procedures, and 8530 patients underwent major vascular operations. Carotid endarterectomy (493 patients), abdominal aneurysm resection (130 patients), renal artery bypass (12 patients), aortofemoral bypass (77 patients), femoral-popliteal-tibial bypass (190 patients), and combined vascular procedures (191 patients) were included. The patients were divided into three groups according to severity of disease, which determined timing of the procedure. Group I (255 patients) underwent simultaneous CAB and peripheral vascular operation because of unstable coronary artery disease and severe vascular disease. The early mortality rate for group I was 4% (10 patients). Seven of the 10 deaths were cardiac. In group II, 279 patients had CAB and peripheral vascular operation during the same hospital admission with the same operative mortality rate (4%, 10 patients). Six deaths were from cardiac causes, three from neurologic causes, and one from hemorrhage. In group III, 559 patients underwent CAB first, then peripheral vascular operation during a separate hospital admission. There were no cardiac-related deaths and only one neurologic-related death (operative mortality rate, 0.2%). These data demonstrate the protective effect of CAB in patients who undergo elective vascular surgery. The increased risk in patients undergoing simultaneous or same admission procedures was related to the severity of the vascular and coronary artery disease and not to the combined operations. Operative complications were not increased by performing simultaneous or same admission procedures.

Actuarial Analysis↗
PubMed1986

Early and late results of coronary endarterectomy. Analysis of 3,369 patients.

The effectiveness of coronary revascularization has been questioned in patients with diffuse coronary disease. Over a 14 year period (1970 to 1984), 30,464 patients underwent surgical revascularization at our institution. Coronary artery bypass alone was done in 27,095 patients and was combined with coronary endarterectomy in 3,369 patients (12.4%). Analysis of preoperative variables revealed an increased incidence of male sex, diabetes mellitus, low ejection fraction (less than 30) and multiple vessel disease in patients requiring endarterectomy. The early results after revascularization indicated a small increase in surgical risk after endarterectomy. The 30 day mortality for bypass alone was 2.6% versus 4.4% for coronary endarterectomy (p less than 0.01). Multivariate analysis identified independent predictors of operative risk: ejection fraction less than 30%, reoperation, age, absence of hyperlipidemia, endarterectomy, and female sex. Early mortality was significantly increased by endarterectomy in the left anterior descending coronary artery (8.5%) compared to endarterectomy in arteries other than the left anterior descending (4.2%) (p less than 0.01). In a sample of 4,473 patients, myocardial complications were also found to be increased after coronary endarterectomy. The incidence of perioperative myocardial infarction in patients undergoing bypass alone was 2.6% versus 5.4% for patients undergoing bypass plus endarterectomy (p less than 0.01). Both fatal and nonfatal cardiac arrests increased (bypass alone, 1.7%; endarterectomy, 3.5%; p less than 0.01). This suggests the failure mode of unsuccessful endarterectomy. Early mortality after coronary endarterectomy decreased substantially from 1970-1976 (6.4%) to 1977-1984 (3.5%; p less than 0.01). Actuarial analysis at 5 years and longer has shown very little difference in the long-term survival rate (coronary bypass, 90%; coronary endarterectomy, 86%), freedom from angina (coronary artery bypass, 58%; coronary endarterectomy, 52%), and freedom from reoperation (coronary artery bypass, 97%; coronary endarterectomy, 98%). Despite the small increase in surgical risk, the early and late results support the selective application of coronary endarterectomy in patients with diffuse distal disease and demonstrate the beneficial long-term effects.

Actuarial Analysis↗
PubMed1986

Surgical repair of aneurysms involving the distal aortic arch.

The surgical approach to aneurysms involving the transverse aortic arch usually requires either techniques for perfusion or hypothermic circulatory arrest. A simplified approach may be warranted when the aneurysmal process begins in the distal aortic arch and spares the innominate artery. Between November, 1975, and January, 1984, 32 patients (22 men, 10 women; median age 61 years) underwent repair of aneurysms of the distal aortic arch by simple cross-clamping of the diseased aortic segment. In each, the aneurysm arose distal to the innominate artery and involved the arch at the origin of the left subclavian or left common carotid artery. Proximal control was achieved by cross-clamping the aortic arch between the innominate and left carotid arteries. No shunts or extracorporeal bypass circuits were employed. Proximal hypertension was controlled by sodium nitroprusside infusion. All patients were heparinized. A mean aortic cross-clamp time of 27 +/- 10 minutes was required for Dacron graft replacement in 28 patients and Dacron patch repair in three patients. Surgical repair was accomplished successfully in 32 patients. The 30 day mortality was 3% with an in-hospital mortality of 6%. There were no complications as a result of myocardial infarction or stroke. Paraplegia (three patients) was related to cross-clamp time (less than 30 minutes, 0/18; greater than 30 minutes, 3/13 [p less than 0.001]) and distal extent of the aneurysm (localized, 0/22; extensive, 3/9 [p less than 0.001]). Transient renal failure (two patients) was related to cross-clamp time (less than 30 minutes, 0/18; greater than 30 minutes, 2/13 [p less than 0.001]). This experience supports the use of simple aortic cross-clamping for aneurysms of the distal aortic arch, especially if an expeditious repair can be accomplished.

Acute Kidney Injury↗
PubMed1985

Hypothermic circulatory arrest for cardiovascular lesions: technical considerations and results.

During a six-year period (1979 to 1984), the technique of hypothermic circulatory arrest was used to operate on 128 patients. Our technique included induction of hypothermia (20 degrees to 24 degrees C) by femoral artery cannulation for return of oxygenated blood, "open" aortic reconstruction, and brief periods of circulatory arrest (range, 5 to 31 minutes; mean, 13 minutes). Eighty patients had dissecting aneurysms of the ascending aorta (42 acute, 38 chronic), 28 had fusiform aortic arch aneurysms, and 13 had annulo-aortic ectasia. Seven had other procedures. Ages ranged from 14 to 79 years (mean, 54 years). Of the 113 patients (88%) who survived the operation and were discharged, 107 are currently alive and well. Only 15 of the 21 deaths occurred within 30 days of operation, and 5 (33%) were in severely hypotensive patients whose operations were begun during active resuscitation. Of the 80 patients admitted with ascending aortic or arch dissection, an in-hospital mortality of 7.5% was achieved. A marked reduction was observed in such complications as postoperative hemorrhage, renal failure, and pulmonary insufficiency with our current hypothermic perfusion methods. Moreover, none of the five neurological complications could be attributed to anoxic cerebral injury during the period of circulatory arrest. This experience indicates that moderate levels of hypothermia provide adequate cerebral protection for most cardiovascular procedures, and our results encourage continued use of this method.

Adolescent↗