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Biomedical subjects

S R Gundry

Publications and source records attributed to S R Gundry.

At least 37 records · Page 2Linked to original sources
PubMed1998

Seven-year follow-up of coronary artery bypasses performed with and without cardiopulmonary bypass.

BACKGROUND: There has been resurgent interest in coronary revascularization performed on the beating heart. Heretofore, there has been no long-term comparison of this technique to traditional coronary artery bypass with cardioplegia. OBJECTIVE: The purpose of this study was to provide a comparison of long-term survival and intervention-free outcome between patient groups subjected to coronary bypass accomplished with or without the use of cardiopulmonary bypass. METHOD: From June 1989 to July 1990, all patients treated for coronary revascularization by three surgeons were considered for coronary revascularization with the heart beating: 107 patients underwent coronary bypass on the beating heart, and 112 patients underwent revascularization with the aid of bypass with cardioplegia. Mean ages (65 +/- 10 years) and risk factors were identical. Patients operated on with the heart beating had 2.4 +/- 0.9 grafts versus 3.2 +/- 1.1 grafts for patients having cardiopulmonary bypass with cardioplegia. RESULTS: At 7-year follow-up, 86 of 107 (80%) patients operated on with the heart beating were alive versus 88 of 112 (79%) patients in whom cardiopulmonary bypass with cardioplegia was used. Cardiac deaths occurred in 13 of 107 (12%) patients in the former group versus 10 of 112 (9%) patients in the latter group. However, 32 of 107 patients operated on with the heart beating (30%) needed catheterization for their symptoms versus 18 of 112 (16%) patients in the bypass with cardioplegia group (p = 0.01). This results in 21 of 107 (20%) patients in the beating heart group needing angioplasty or a second coronary bypass versus only 8 of 112 (7%) patients in the bypass with cardioplegia group. No patient in the bypass with cardioplegia group required reoperation. Most of the reinterventions for the beating heart group were percutaneous transluminal coronary angioplasty (15 of 21 [71%] patients). CONCLUSION: Despite one less graft per patient, survival and cardiac death rates were similar for the two groups. However, twice as many patients in the beating heart group required recatheterization (30% versus 16%), and 20% needed a second intervention. Only 7% of the bypass with cardioplegia group required reintervention. Limited revascularization of the beating heart provides long-term results comparable to full revascularization with cardiopulmonary bypass, but at the cost of a threefold increase in reinterventions.

Aged↗
PubMed1998

Prolonged discordant xenograft survival and delayed xenograft rejection in a pig-to-baboon orthotopic cardiac xenograft model.

OBJECTIVE: Our objectives were to study delayed xenograft rejection and the effectiveness of pretransplantation total lymphoid irradiation combined with immunosuppression on rejection in a pig-to-baboon cardiac xenograft model. METHODS: Baboons were treated with pretransplantation total lymphoid irradiation, cyclosporine A (INN: ciclosporin), and methotrexate. Orthotopic pig-to-baboon cardiac transplantations were performed after depletion of circulating xenoreactive natural antibody by pretransplantation donor organ hemoperfusion. Tissue samples were collected for immunologic and immunopathologic evaluation. RESULTS: Pig cardiac xenografts survived more than 18 and 19 days without evidence of hyperacute rejection. Immunologic analysis of serum samples demonstrated that circulating xenoreactive natural antibody levels did not return to pretransplantation levels. The production of xenoreactive natural antibodies from the recipient's splenocytes was inhibited completely. Histologic examination of xenografts showed the feature of acute vascular rejection. Immunohistochemical studies demonstrated infiltration of cardiac xenografts by large numbers of macrophages, small numbers of natural killer cells, and a few T cells. The infiltrating macrophages also showed expression of interleukin-1 and tumor necrosis factor. Diffuse deposition of immunoglobulin G, C1Q, C3, and fibrin on xenograft vasculature was observed. Interleukin-2 expression was not found in rejected cardiac xenografts. Xenograft endothelial cells also showed evidence of activation (expression of cytokines interleukin-1 and tumor necrosis factor). CONCLUSIONS: This study demonstrates prolonged discordant cardiac xenograft survival and delayed xenograft rejection in a pig-to-baboon model. The delayed xenograft rejection is mediated by both humoral and cellular mechanisms. Pretransplantation total lymphoid irradiation combined with cyclosporine A and methotrexate can inhibit xenoreactive natural antibody production but not elicited antipig antibody production and the xenoreactivity of macrophages.

Animals↗
PubMed1998

Heart transplantation in infants and children with situs inversus.

BACKGROUND: Recipient situs inversus has always represented a technical challenge during heart transplantation. OBJECTIVE: A simplified operative strategy for heart transplantation in a recipient with atrial situs inversus is described. METHODS: Fifteen pediatric recipients with situs inversus accompanying other complex congenital heart disease or dilated cardiomyopathy having "orthotopic" heart allotransplantation in one center, between 1985 and 1997, were reviewed retrospectively. A nearly uniform, simplified technical approach to transplantation was used and is described. RESULTS: Fourteen of these recipients with complex malformations survived the transplantation. Morbidity relating to surgical technique has been limited to partial (n = 2) or complete (n = 1) late obstruction of superior vena caval drainage; each case was managed successfully by interventional cardiologic techniques. Actuarial survival after transplantation compares favorably with that among 290 infants and children with atrial situs solitus who underwent heart transplantation. CONCLUSIONS: Systemic atrial malposition, including situs inversus, does not limit successful heart transplantation by the simplified method described.

Adolescent↗
PubMed1998

Posttransplant recoarctation of the aorta: a twelve year experience.

OBJECTIVES: This study was undertaken to investigate the incidence of posttransplant recoarctation of the aorta, delineate the mode of presentation, identify risk factors that predict recoarctation and examine the results of intervention for posttransplant recoarctation. BACKGROUND: Patients with aortic arch hypoplasia require extended arch reconstruction at transplant, with an inherent possibility of subsequent recoarctation of the aorta. METHODS: This was a retrospective review of all children (age <18 years) who underwent cardiac transplantation over a 10-year period. Collected data included pretransplant diagnosis, details of the transplant procedure and posttransplant data including development of recoarctation of the aorta, interventions for recoarctation and the most recent follow-up assessment of the aortic arch. RESULTS: Two hundred eighty-eight transplants were performed on 279 children (follow-up = 1,075 patient-years; range 0 to 133 months, median 43.7). Thirty-two of 152 patients (21%) who underwent extended aortic arch reconstruction subsequently developed recoarctation. All but one patient developed recoarctation within 2 years after transplant; 87% were hypertensive at presentation. Of 30 patients who underwent intervention for recoarctation (balloon angioplasty [n = 26] and surgical repair of recoarctation [n = 4]), 26 (87%) have remained recurrence-free (follow-up = 133 patient-years; range 8 to 106 months, median 47). CONCLUSIONS: The high frequency of recoarctation after cardiac transplantation with extended aortic arch reconstruction mandates serial echocardiographic evaluation of the aortic arch. Patients typically present with systemic hypertension within the first two years after transplantation. Balloon angioplasty is a safe, effective and durable method of treatment.

Adolescent↗
PubMed1998

Heart transplantation for hypoplastic left heart syndrome: modified technique for reducing circulatory arrest time.

BACKGROUND: The surgical technique of heart transplantation as therapy in infants with hypoplastic left heart syndrome was first reported over a decade ago. Since that time, incremental refinements have evolved that both facilitate the operation and potentially reduce the perceived neurologic hazards associated with the use of hypothermic circulatory arrest. METHODS: Minor technical adjustments have permitted infant heart transplantation to be accomplished with relative ease while markedly limiting the need for complete circulatory arrest. Low-flow hypothermic systemic perfusion is used for atrial implantation, reserving circulatory arrest for arch reconstruction only. This is accomplished by use of an active (pump) sucker for venous return. RESULT: Mean circulatory arrest time with the current technique has been 26 minutes. CONCLUSION: Minor technical refinements have resulted in a marked reduction in hypothermic circulatory arrest time during infant heart transplantation for hypoplastic left heart syndrome.

Cardiopulmonary Bypass↗
PubMed1997

Prolonged discordant cardiac xenograft survival in newborn recipients.

BACKGROUND: We previously demonstrated very low levels of xenoreactive natural antibodies in newborns, suggesting the possibility of prolongation of xenograft survival in newborn recipients. We used a pig-to-newborn goat heterotopic cardiac xenograft model to examine our hypothesis that hyperacute rejection would be absent in newborn recipients and that both humoral and cellular rejection would participate in the late phase of discordant xenograft rejection. METHODS AND RESULTS: The serum of newborn goats was found to have very low titers of natural anti-pig antibodies. Newborn pig hearts were transplanted heterotopically into the neck of four unmanipulated newborn goats: none of these xenografts underwent hyperacute rejection. Dilation of the xenografts and decreased contractility were observed 4 to 6 days after transplantation, and the xenografts eventually ceased functioning between 6 and 8 days after transplantation. Blood samples collected after transplantation demonstrated a dramatic increase in anti-pig xenoantibody titers and correlated with histological studies demonstrating features consistent with delayed humoral rejection, including reactive vascular endothelial and perivascular stromal cells, marked capillary congestion, and interstitial hemorrhages. Scant to diffuse perivascular and interstitial infiltration of activated lymphoid cells occurred. CONCLUSIONS: Our study demonstrates that hyperacute rejection does not occur, allowing limited prolongation of xenograft survival in a pig-to-newborn goat cardiac xenograft model. We propose that this is attributable, at least in part, to the very low titers of natural antibodies in newborn recipients. Delayed xenograft rejection, however, remains an important problem in these newborn recipients. This delayed xenograft rejection is likely the result of both humoral and cellular rejection mechanisms.

Animals↗
PubMed1997

Echocardiographic recognition of iatrogenic aortic valve leaflet perforation.

BACKGROUND: There is a paucity of literature regarding iatrogenic aortic valve perforation after cardiac operations performed in the vicinity of the aortic valve. This report describes the echocardiographic recognition of iatrogenic aortic valve perforation. METHODS: Among 6 patients who had previously under-gone non-aortic valve cardiac operations, a diagnosis of iatrogenic aortic regurgitation was made by transthoracic two-dimensional echocardiography and Doppler color flow imaging. RESULTS: The location of the aortic valve leaflet perforation varied and depended on the site of the previous intracardiac lesion repair. Repeat operations in 5 patients confirmed the echocardiographic findings. Aortic valve repair was confirmed in 2 patients by transesophageal echocardiography, whereas aortic valve replacement became necessary in 2 other patients. A fifth patient with acquired cardiomyopathy underwent orthotopic heart transplantation. CONCLUSIONS: A detailed two-dimensional echocardiographic examination, along with color flow imaging, should be done to evaluate iatrogenic aortic valve perforation in patients with a new murmur of aortic regurgitation after cardiac operations in proximity to the aortic valve. Precise preoperative diagnosis of this lesion allows optimal surgical planning and treatment.

Adult↗
PubMed1997

The optimal Fontan connection: a growing extracardiac lateral tunnel with pedicled pericardium.

OBJECTIVE: The concept of a lateral tunnel for the Fontan operation is now widely accepted. Most lateral tunnels are constructed intraatrially with the use of aortic crossclamping. Construction of extracardiac lateral tunnels with the use of homografts or other nonviable tubes eliminates aortic crossclamping but lacks growth potential in length or width. The native pericardium, which is "sealed" posteriorly along the pulmonary artery, atrium, and inferior vena cava, could be turned down onto the right atrium to form a viable extracardiac lateral tunnel. METHODS: We designed and successfully constructed extracardiac lateral tunnels using viable autologous pericardium, pedicled on its lateral blood supply, in 19 patients aged 9 months to 5 years. All patients had a previous Glenn shunt; five patients had dextrocardia and a midline inferior vena cava. The patients' inferior vena cava-right atrial connection was opened transversely and the right atrial opening was sutured to its back wall, keeping the eustachian valve in the inferior vena cava. The underside of the right pulmonary artery was opened longitudinally; its inferior edge was sewn to the adjacent pericardial reflection. Any "pocket" or depressions in the posterior pericardium along the pulmonary veins were closed with running suture. Two incisions were made in the right pericardium down to the phrenic nerve parallel to the inferior vena caval and pulmonary arterial openings. This pedicled pericardium was trimmed and sewn as a roof to the upper edges of the inferior vena cava and pulmonary artery openings and then sewn longitudinally along the unopened right atrial wall, completing the viable extracardiac lateral tunnel. Although no fenestrations were used, these could be made during construction, or more significantly, owing to the lack of thick walled structures, in the catheterization laboratory in the postoperative period. RESULTS: All 19 patients had respiratory/cardiac pulsations in the pulmonary arteries owing to the compressible lateral tunnel. At follow-up of up to 2 1/2 years, all tunnels are growing and no obstructions have occurred. CONCLUSION: The viable autologous pericardial extracardiac lateral tunnel can be constructed without cardiac ischemia, can be fenestrated in the postoperative period, and forms a compressible, nonthrombogenic conduit capable of growth, which can be constructed early in infancy.

Child, Preschool↗
PubMed1997

Reanimation: overcoming objections and obstacles to organ retrieval from non-heart-beating cadaver donors.

Interest in the retrieval of organs from non-heart-beating cadaver donors has been rekindled by the success of transplantation of solid organs and the insufficient supply of donor organs currently obtained from heart-beating cadaver donors. There are currently two retrieval techniques being evaluated, the in situ cold perfusion approach and the controlled death approach. Both, however, raise ethical concerns. Reanimation is a new method which has been used successfully in animals. We believe this new approach overcomes the ethical objections raised to these other methods.

Animals↗
PubMed1997

Limitations to survival for infants with hypoplastic left heart syndrome before and after transplant: the Loma Linda experience.

Untreated, hypoplastic left heart syndrome is a lethal cardiac defect. Heart transplant has become an accepted therapeutic option for this condition. However, significant limitations to survival remain for infants with this condition who are referred for heart transplantation. Attention to the prevention, early detection, and management of common problems occurring at each stage of the transplantation process is important for improving survival rates. This study retrospectively reviewed the cases of 195 infants with hypoplastic left heart syndrome registered for heart transplantation at Loma Linda University Medical Center between November 1985 and July 1996 to determine causes of death. During the waiting period, progressive cardiac failure and complications from interventional procedures were the leading causes. In the early postoperative period, technical issues and acute graft failure were most important, whereas late deaths (more than 30 days after transplant) were most often related to rejection and posttransplant coronary artery disease.

California↗
PubMed1997

Is there a safe limit to coronary sinus pressure during retrograde cardioplegia?

Although retrograde cardioplegia (RC) delivered via the coronary sinus (CS) is now used routinely, the pressure at which RC can be safely delivered is thought to be 50 to 60 mm Hg. Such practice is based on experiments performed on working, beating hearts with CS ligation and arterial inflow into both the coronary arteries and veins (Beck procedure). However, no data exist on arrested, vented hearts, as occurs clinically during RC. We studied the acute effect of 10 cc/kg of blood RC delivered into the CSs of 16 adult vented pig hearts, which were randomly assigned to four groups of four hearts each according to the CS pressure maintained during perfusion: 40, 80, 100, and 120 mm Hg. After RC, hearts were excised, cut in bread-loaf sections, examined grossly, and then fixed and stained. Sections of right ventricle, septum, and left ventricle were then examined by two blinded cardiac pathologists and two blinded surgeons and scored for the presence of extravascular hemorrhage. None of the 16 hearts tested showed any evidence of gross or microscopic hemorrhage; all hearts showed normal myocardial preservations and structure, including all hearts at 100 and 120 mm Hg CS perfusion pressure. We conclude that CS pressures up to 120 mm Hg cause no extravasation of blood into the myocardium in the vented, arrested heart. These results contradict studies on the working, beating heart, and suggest that high pressures in the CS are well tolerated during RC.

Animals↗
PubMed1996

Uniformity of perfusion in all regions of the human heart by warm continuous retrograde cardioplegia.

BACKGROUND: Animal models have suggested that retrograde cardioplegia may be poorly distributed to septal and right ventricular regions of the heart; if true, this may have dangerous implications for warm continuous retrograde cardioplegia in humans. We have previously shown that blood gases from coronary arteries during warm continuous retrograde cardioplegia represent postcapillary "venous" gases and are reflective of myocardial perfusion. METHODS: To determine regional differences in perfusion during warm continuous retrograde cardioplegia we obtained blood gases from three regions of the heart in 141 consecutive patients undergoing coronary artery bypass grafting, aortic valve replacement, or both. Right heart perfusion was determined by blood gases from the right coronary artery orifice, acute marginal, or posterior descending coronary arteries; circumflex or lateral wall perfusion was determined by samples from obtuse marginal or intermediate coronary arteries; and anterior wall/septal perfusion was determined by left anterior descending and diagonal coronary artery blood gases. Warm continuous retrograde cardioplegia flow ranged from 150 to 300 mL/min depending on heart size. A mean of 4 +/- 1 samples/patient were obtained. RESULTS: There were no regional differences in postcapillary pH, carbon dioxide tension, or CO2 production during warm continuous retrograde cardioplegia. Oxygen tensions were lower in the right and anterior/septal regions of the heart, implying more O2 uptake. No regional acidosis, consistent with poor perfusion, could be detected. CONCLUSIONS: We conclude that, unlike experimental models, regional myocardial perfusion, including the right heart, is uniform during "high-flow" warm continuous retrograde cardioplegia in humans.

Carbon Dioxide↗
PubMed1996

Neurologic sequelae of deep hypothermic circulatory arrest in cardiac transplant infants.

BACKGROUND: Considerable controversy exists experimentally and clinically regarding adverse neurologic effects that may follow deep hypothermic circulatory arrest. Moreover, the techniques of DHCA have never been standardized. METHODS: We prospectively studies the neurodevelopmental outcome in 38 infants undergoing cardiac transplantation using DHCA before the age of 4 months (mean age, 37.0 days). Neurodevelopmental outcome in the 22 boys and 16 girls was tested up to 2.5 years after transplantation using Bayley scale of infant development. Bayley scores were compared with the rate of core cooling and the length of DHCA in all patients. Deep hypothermic circulatory arrest was accomplished using an asanguineous prime resulting in hematocrits of 5% +/- 5% and ionized Ca2+, 0.4 +/- 0.1 mmol/L. No surface precooling was used, but the head was packed in ice. Mean cooling time was 14.0 +/- 3.5 minutes, resulting in rectal temperatures of 18 degrees +/- 2.5 degrees C. Duration of DHCA ranged from 42 to 70 minutes (mean duration, 56.0 +/- 6.6 minutes). RESULTS: Postoperatively, the mean Bayley psychomotor development index was 91 (range, 50 to 130) and mental development index was 88 (range, 50 to 130). No relationship was found between either the rate of cooling or the duration of DHCA and Bayley scores (r = 0.227 and r = 0.322, respectively). CONCLUSIONS: These data suggest that neither the rate of cooling nor DHCA times between 42 and 70 minutes using profoundly low hematocrits and low ionized calcium levels has any measurable effect on neurologic outcome up to 2.5 years postoperatively. It is possible that adverse neurologic outcomes from DHCA reflect particular methods of achieving DHCA.

Central Nervous System↗
PubMed1996

Transplantation as a primary treatment for hypoplastic left heart syndrome: intermediate-term results.

BACKGROUND: Hypoplastic left heart syndrome is a lethal malformation. For the last 10 years, orthotopic cardiac transplantation has been our preferred treatment for infants with hypoplastic left heart syndrome. METHODS: One hundred seventy-six infants with hypoplastic left heart syndrome were entered into a cardiac transplant protocol between November 1985 and November 1995. Interventional procedures to stent the ductus arteriosus or enlarge the interatrial communication were performed in 8 and 35 patients, respectively. Thirty-four patients (19%) died during the waiting period, and 142 infants underwent cardiac transplantation. Age at cardiac transplantation ranged from 1.5 hours to 6 months (median, 29 days). The majority of grafts were oversized, and the median graft ischemic time was 273 minutes (range, 60 to 576 minutes). The implantation procedure used a period of hypothermic circulatory arrest ranging from 23 to 110 minutes (median, 53 minutes). Repair of other significant defects included interrupted aortic arch and total or partial anomalous pulmonary venous connection. RESULTS: There were 13 early and 22 late deaths. Patient actuarial survival at 1 month and at 1, 5 and 7 years was 91%, 84%, 76%, and 70% respectively. Half of the late deaths were due to rejection. Severe graft vasculopathy was confirmed in 8 patients. Retransplantation was performed in 5 patients for graft vasculopathy 4 and rejection 1. Lymphoblastic leukemia developed in 1 patient 3 years after cardiac transplantation. CONCLUSIONS: Cardiac transplantation can be performed in infants with hypoplastic left heart syndrome with good operative and intermediate-term results. Improved survival can be achieved with increased donor availability, better management of rejection, and control of graft vasculopathy.

Actuarial Analysis↗
PubMed1996

Delayed primary repair of intrathoracic esophageal perforation: is it safe?

The management of intrathoracic esophageal perforation with delayed diagnosis is a subject of controversy. Because of the obvious advantages of primary repair as a simple single-stage operation, this technique was preferentially used to treat 18 of 22 consecutive patients with esophageal perforation. These patients were stratified into three groups according to the time interval between perforation and repair: group A, less than 6 hours, five patients (28%); group B, 6 to 24 hours, six patients (33%); and group C, more than 24 hours, seven patients (39%). Group A patients were older (p < 0.05) and group B had fewer iatrogenic perforations (B, 17%; A, 80%; C, 57%, p < 0.1). Additional tissue was used to buttress the repair site in all three groups (A, 3/5 patients, 60%; B, 4/6 patients, 67%; C, 6/7 patients, 86%; p = not significant). In seven patients (39%), a fundic wrap was used to reinforce the site of primary repair. The outcomes of the three groups were analyzed. Group A had the lowest proportion of postoperative leaks (A, 0/4 patients, 0%; B, 4/6 patients, 67%; C, 5/6 patients, 83%; p < 0.05) and postoperative morbidity (A, 2/5 patients, 40%; B, 6/6 patients, 100%; C, 6/7 patients, 86%; p < 0.1). However the increased incidence of leak and morbidity did not lead to an increase in mortality. One death occurred in each group, with an overall mortality of 17% (A, 1/5 patients, 20%; B, 1/6 patients, 17%; C, 1/7 patients, 14%; p = not significant). We conclude that in the era of advanced intensive care capabilities, primary repair of intrathoracic esophageal perforation can be safely accomplished in most patients regardless of the time interval between perforation and operation. Leakage at the suture site is common unless primary repair is carried out without delay. Postoperative leakage, however, is usually inconsequential and does not necessarily result in an adverse outcome.

Aged↗