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Biomedical subjects

J M Duncan

Publications and source records attributed to J M Duncan.

At least 55 records · Page 3Linked to original sources
PubMed1991

Innominate artery occlusive disease: surgical approach and long-term results.

We reviewed our experience with 54 patients who underwent innominate artery revascularization during a 10-year period. Their age range was from 16 to 75 years (mean, 49.8 years). The innominate artery alone was involved in 21 patients (39%); the remaining patients had additional arch vessel obstructions. Before operation, neurologic symptoms occurred in 25 patients (46%), arm ischemia related to claudication and microembolization occurred in 8 patients (14%), a combination of symptoms occurred in 17 patients (32%), and no symptoms were noted in 4 patients (8%). The extrathoracic approach to surgery was used in 16 patients (30%). Eleven of the 38 patients in whom the intrathoracic approach was used had endarterectomy of the innominate artery; in three of those, the procedure was combined with left common carotid endarterectomy. Bypass grafts were used in the other 27 patients undergoing procedures with an intrathoracic approach; in six of those, bypass was combined with carotid endarterectomy. No operative deaths occurred. Perioperative revascularization failure occurred in four cases; all of those patients underwent a second revascularization procedure, with a secondary patency rate of 100%. In four patients, late occlusion was noted at 6 months and at 1, 1.5, and 10 years. One patient had a permanent perioperative neurologic deficit in the distribution of the left carotid artery after a combined common carotid endarterectomy/innominate endarterectomy procedure. No neurologic deficits were directly related to the innominate artery territory. Long-term actuarial survival was 83% at 10 years. Early and late graft failures were related to inadequate inflow in bypass grafts, progression of distal disease in arteritis, and primary closure in endarterectomy.

Adolescent↗
PubMed1991

A community study of vitamin B12 and folate levels in the elderly.

OBJECTIVE: To measure the prevalence of low serum vitamin B12, folate, and red cell folate levels and their relationship with other nutritional indices. DESIGN: Prospective survey of elderly subjects using radioisotope dilution assays. SETTING: Primary care medical center, Christchurch, New Zealand. PATIENTS: 257 elderly subjects (age 65 years and over), residing in their own homes or in residential homes, were randomly selected. Of these, 204 (79%) participated. The study population was comparable to the elderly population of New Zealand. MAIN OUTCOME MEASURES: Vitamin B12, serum, and red cell folate levels. RESULTS: The prevalence rates for low levels of serum vitamin B12, folate, and red cell folate were 7.3%, 1%, and 3.3%, respectively. The elderly cohort had lower vitamin B12 (P less than 0.001) but higher serum and red cell folate levels (P less than 0.001) than our normal reference range (age 18-65 years). Red blood cell folate levels showed positive correlations with nutritional indices and mental test scores. No correlations were found between vitamin B12 levels and diet or other nutritional indices. CONCLUSIONS: Low folate levels in older people living at home are infrequent findings. In contrast low vitamin B12 levels are more common. Poor diet and undernutrition may contribute to low folate levels, but these factors are less important for the low B12 levels found.

Aged↗
PubMed1990

Heart transplantation in Jehovah's Witnesses. An initial experience and follow-up.

More than 25 years of experience performing heart surgery on Jehovah's Witnesses has culminated in successful cardiac transplantation without administering blood products in five patients (mean age, 44.4 +/- 8.3 years) of this faith. The use of blood-conserving methods, iron supplementation, bone marrow-sparing maintenance immunotherapy, and brisk postoperative diuresis has added to the efficacy of cardiac transplantation in these patients. No perioperative deaths occurred, and early follow-up studies have shown that these patients have not been more susceptible to higher graft rejection rates due to the lack of pretransplant blood transfusions. As more Jehovah's Witnesses undergo heart transplantation in the future, comparison with other recipients who allow pretransplant blood transfusions may lead to a better understanding of rejection immunobiology. We conclude that cardiac transplants may be safely offered to Jehovah's Witnesses without fear of a uniformly poor outcome.

Adult↗
PubMed1990

Extension of donor criteria in cardiac transplantation: surgical risk versus supply-side economics.

To combat the continuing shortage of ideal donor hearts, we have used cardiac allografts from high-risk donors for critically ill recipients. We defined high-risk donor variables as age greater than 40 years, systemic (noncardiac) infection, cardiopulmonary resuscitation greater than 3 minutes, ischemic time longer than 5 hours, weight more than 20% less than that of the recipient, and requirements for high doses of inotropes. Of the 305 donors we have used, 73 (23.9%) have been high-risk, with 59/73 (80.8%) exhibiting one variable, 12/73 (16.4%) exhibiting two variables, and 2/73 (2.7%) exhibiting three variables. No correlation was found between the number of donor variables and a poor postoperative result. No infectious complications occurred in 17 patients receiving hearts from potentially infected donors. Hospital mortality rates (30 day) for recipients of high-risk donor versus non-high-risk donor hearts were 8.2% and 6.9%, respectively (not significant). The 1-, 6-, and 12-month actuarial survival rates were 91.7%, 81.2%, and 75.9% for the high-risk donor group and 93.5%, 80.3%, and 77.8% for the non-high-risk donor group (not significant). Among survivors with high-risk donor hearts, mean left ventricular ejection fractions were 0.54 +/- 0.08 at 3 months, 0.55 +/- 0.08 at 1 year, and 0.54 +/- 0.09 at 2 years after transplantation. These results suggest that accepting less than ideal donor hearts can be safe and might be considered when better options are not available.

Adult↗
PubMed1990

First human use of the Hemopump, a catheter-mounted ventricular assist device.

The Hemopump, a catheter-mounted, temporary ventricular assist device, consists of an external electromechanical drive console and a disposable, intraarterial axial-flow pump (21F). Power is transmitted percutaneously to the pump by a flexible drive shaft within the catheter. The device is positioned in the left ventricle by way of the femoral artery approach or through the ascending aorta. Blood is drawn from the left ventricle through the transvalvular inlet cannula and pumped into the aorta. As of December 1988, the Hemopump had successfully supported the circulation of 7 patients (5 men, 2 women) ranging in age from 44 to 72 years (mean age, 59 years) and suffering from cardiogenic shock (cardiac index less than 2.0 L/min/m2). Indications for use included failure to be weaned from cardiopulmonary bypass in 4 patients, acute myocardial infarction in 1, severe cardiac allograft rejection in 1, and donor heart failure in 1. Duration of support ranged from 26 to 113 hours (mean, 66 hours). Although 5 patients demonstrated transient hemolysis, none experienced infection, thrombosis, or vascular injury. Hemodynamic variables improved in all patients during support by the device. As of December 1988, 5 of the 7 patients were alive more than 30 days after support had been discontinued, and 3 of these patients were discharged from the hospital. On the basis of our initial clinical results, the Hemopump, which does not require a major surgical procedure for insertion, provides effective, temporary circulatory support in patients with potentially reversible cardiac failure.

Adult↗
PubMed1990

Rapid placement of the Hemopump and hemofiltration cannula.

Hypervolemia, a potential complication in patients on ventricular assist device support, can be managed by use of continuous arteriovenous hemofiltration. The Hemopump, a new catheter-mounted, transaortic axial-flow ventricular assist device, and the vascular access catheter for the Diafilter-30 Hemofilter system, used in continuous arteriovenous hemofiltration, are both usually inserted by way of the femoral artery. Because placing two large catheters in the femoral artery of a patient with peripheral vascular disease can compromise circulation, a technique for placing them in the abdominal aorta was developed. Two patients have undergone combined Hemopump and hemofiltration treatment, and neither experienced complications. Such techniques may benefit more patients in the future, as the usefulness of the Hemopump is proved.

Aorta, Abdominal↗
PubMed1990

Use of potentially infected donor hearts for cardiac transplantation.

Despite the nationwide shortage of heart donors, more patients, some of whom are critically ill, are being accepted as candidates for transplantation. Thus, on occasion, we have liberalized our donor criteria to meet the demand. We have recently transplanted 16 potentially infected donor hearts into critically ill recipients. Of these 16 donors, 7 had multiple positive blood cultures as follows: Streptococcus pneumoniae (3), Staphylococcus aureus (2), Klebsiella pneumoniae (1), and Enterobacter sp (1). Seven other donors were accepted despite high fevers (rectal temperature greater than 38.9 degrees C), leukocytosis (greater than 18 x 10(9)/L [greater than 18,000 cells/microL]), and pulmonary infiltrates with positive sputa (Enterobacter [3], Klebsiella pneumoniae [2], and Staphylococcus [2]). Two other donors with hepatitis B surface antigen positivity were deemed at high risk but were used because the recipients were in immediate need. Early mortality (less than or equal to 30 days) among the recipients was 3/16 (18.7%) with 1 patient dying of uncontrolled allograft rejection, 1 of hepatic failure, and 1 of Pseudomonas septicemia. Late mortality (greater than 30 days after operation) occurred in 6 patients: 2 patients died of hepatic failure, 3 died of graft atherosclerosis, and 1 died of iatrogenic hemorrhage after a liver biopsy. Only 1 patient died of infection unrelated to that of the donor, and the other patients had no infectious complications resulting from the organisms identified in their respective donors. Use of potentially infected donor hearts resulted in surprisingly few infectious complications in this group of recipients. This practice can be safe and should be considered when other options are unavailable.

Adult↗
PubMed1990

Risk factors for development of accelerated coronary artery disease in cardiac transplant recipients.

Allograft coronary artery disease (CAD) is the major determinant of long-term survival following heart transplantation (HTx). In a group of 210 heart transplant recipients, we diagnosed CAD in 54 (27.1%) by coronary angiography, postmortem examination or examination of the transplanted heart at the time of retransplantation. Retrospective analysis of potential risk factors for the development of CAD was performed for both immunological (rejection pattern, immunosuppressive therapy, cytomegalovirus [CMV] infection), and nonimmunological (hyperlipidemia, smoking, hypertension, diabetes mellitus, obesity) risk factors. The total number of rejection episodes correlated significantly with the occurrence of CAD (P less than 0.05), showing that patients who experienced two or more rejection episodes had an incidence of CAD of 40%, as opposed to a 23% incidence in patients who experienced no rejection. A composite rejection score derived from multivariate regression analysis of the severity, frequency, and timing of acute cardiac rejection episodes was found to correlate with the development of CAD (P less than 0.05). Postoperative arterial hypertension also correlated significantly with the onset of CAD (P less than 0.01), with a 92.6% incidence of hypertension in the group with CAD versus 76.3% in the group without CAD. Smoking after transplantation correlated significantly with the occurrence of CAD (P less than 0.05). There was no significant correlation with other analyzed factors in this group of patients. In this review, the development of CAD after heart transplantation correlated with treated allograft rejection. Aggressive treatment of hypertension and cessation of smoking may contribute to alleviation of this serious complication.

Coronary Disease↗
PubMed1990

Concomitant donor heart coronary artery bypass grafting during orthotopic heart transplantation.

A 54-year-old diabetic woman with severe cardiomyopathy was placed on our heart transplant candidate list. The patient's condition rapidly worsened and a potential donor-a 45-year-old man whose blood was compatible with that of our patient-was located. Because of the donor's age, coronary arteriography was done, and stenosis in the midleft anterior descending coronary artery was identified. Since the patient's status was critical, the donor heart was accepted despite the presence of stenosis. We used the recipient's internal mammary artery to bypass the stenosis in the left anterior descending artery of the donor heart after performing a standard orthotopic heart transplant. The patient's postoperative course has been relatively free of complications, and the cardiac allograft has functioned well. The early results in this patient are comparable to those of our historical transplant control group. We suggest that the impact of donor organ shortages may be lessened by use of innovative procedures and extended donor selection criteria.

Journal Article↗
PubMed1989

Effect of prior cardiac surgery on survival after heart transplantation.

We conducted a retrospective analysis of 182 adult orthotopic heart transplant patients who underwent operations at our institution between July 1982 and October 1987 to determine whether prior cardiac operation affects survival. Group I included the 72 patients (39.6%) who had undergone a previous cardiac operation or operations and group II, the 110 (60.4%) who had not. The mean age of the patients in group I was 52.1 +/- 8.1 years and in group II, 46.1 +/- 10.2 years (p less than 0.01). The incidence of ischemic heart disease was 86.1% in group I and 29.1% in group II (p less than 0.01). All patients received cyclosporine-based immunosuppression. More patients in group I than in group II required reoperation for bleeding after transplantation: 18 (25.0%) versus 9 (8.2%) (p less than 0.01). The actuarial 1-year and 3-year survival rates were 77.6% and 66.5%, respectively, for group I and 77.1% and 66.3%, respectively, for group II. Because both groups had similar survival rates, we believe that prior cardiac operation in heart transplant recipients does not compromise long-term survival.

Adult↗
PubMed1989

Implantation techniques for the Hemopump.

Techniques for implantation of the Hemopump, an intraarterial, axial-flow circulatory assist device, are described. The Hemopump, which is currently undergoing clinical investigation, has been used successfully to treat patients experiencing profound left ventricular failure in a variety of clinical situations, including postcardiotomy shock, acute myocardial infarction, cardiac allograft rejection, and cardiac allograft failure.

Cardiopulmonary Bypass↗
PubMed1988

Cardiac transplantation in patients over 60 years of age.

Cardiac transplant programs have routinely excluded patients over 55 years of age from consideration as transplant candidates. The Texas Heart Institute modified this policy of using age as a contraindication to transplantation. Between July, 1982, and August, 1987, a total of 200 cardiac transplants were performed, 28 (14%) of which were in patients over 60 years of age, the eldest being 66 years old at the time of transplant. Our immunosuppressive regimen consisted primarily of cyclosporine and prednisone. In 1985, azathioprine was added in an effort to decrease dosages of cyclosporine, thereby decreasing its associated nephrotoxicity. The incidences of rejection and infection were 1.2 and 1.4 episodes/patient, respectively, for those over 60 years of age versus 1.7 and 1.3 episodes/patient, respectively, for those less than 60 years of age. Of the 28 patients, 23 are alive and well. Four deaths were caused by infection, and the other by diffuse coronary arteritis. The one-year actuarial survival for patients over 60 years of age was 83%, compared with 75% for the other transplant patients. We conclude that persons over 60 years of age can undergo cardiac transplantation with results equal to or perhaps better than those of other heart transplant patients. Our experience suggests that advanced age should not be considered a major contraindication to cardiac transplantation.

Actuarial Analysis↗
PubMed1988

Cardiac transplantation in a Jehovah's witness.

Between July 1982 and October 1987, surgeons at our institution performed 215 cardiac transplantation procedures, 1 of which was in a 46-year-old Jehovah's Witness with congestive cardiomyopathy, who required preoperative intra-aortic balloon pump support. At surgery, the cardiopulmonary bypass system was primed with 1600 ml of Ringer's lactate solution and dextrose. In the 57 minutes during which the patient was on cardiopulmonary bypass, the intra-aortic balloon was removed and successful orthotopic heart transplantation was performed. No supplemental blood or blood product was used, either during or after the procedure. The estimated intraoperative blood loss was 300 ml, and the postoperative chest tube drainage amounted to 1495 ml. Postoperative hematologic abnormalities (mild hypoprothrombinemia, mild thrombocytopenia, mild platelet dysfunction, and moderate hypochromic microcytic anemia) were corrected with Imferon, vitamin K, and desmopressin acetate administered intravenously, and with ferrous sulfate administered orally. This case, which to our knowledge is only the 2nd cardiac transplant in a Jehovah's Witness, further establishes that these patients can undergo even the most major of open-heart procedures without supplemental blood.

Journal Article↗