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Biomedical subjects

R L Kormos

Publications and source records attributed to R L Kormos.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

ECMO support for adult patients with acute respiratory failure.

The authors analyzed factors that may influence the outcome of adult patients with respiratory failure who were treated with ECMO. Between December 1990 and July 1995, the authors used ECMO to support 33 patients (age range, 17-56 years) with respiratory failure from adult respiratory distress syndrome (ARDS; n = 9), primary graft failure after lung transplantation (n = 16), late graft failure after lung transplantation (n = 5), and miscellaneous reasons (n = 3). Twenty (61%) patients were successfully weaned from ECMO, and 13 (39%) survived to hospital discharge. Venoarterial ECMO was used in 46% of survivors, compared with 60% of nonsurvivors (p = 0.43). The time on mechanical support before ECMO and the duration on ECMO for survivors and nonsurvivors was 2.9 +/- 1.8 days vs 5.0 +/- 1.3 days (p = 0.35), and 6.5 +/- 1.8 days vs 5.7 +/- 1.1 days (p = 0.68), respectively. Compared with the nonsurvivors, survivors had higher PF ratios (PaO2/FIO2; 104 +/- 33 vs 81 +/- 8, p = 0.43) before ECMO was initiated, although the differences were not significant. Among the patients who received ECMO for primary graft failure, 75% were weaned from ECMO, and 56% survived to discharge. ECMO is beneficial for adult patients with respiratory failure, especially those with primary graft failure after lung transplantation.

Acute Disease↗
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Progress on development of the Nimbus-University of Pittsburgh axial flow left ventricular assist system.

Nimbus Inc. (Rancho Cordova, CA) and the University of Pittsburgh have completed the second year of development of a totally implanted axial flow blood pump under the National Institutes of Health Innovative Ventricular Assist System Program. The focus this year has been on completing pump hydraulic development and addressing the development of the other key system components. Having demonstrated satisfactory pump hydraulic and biocompatibility performance, pump development has focused on design features that improve pump manufacturability. A controller featuring full redundancy has been designed and is in the breadboard test phase. Initial printed circuit layout of this circuit has shown it to be appropriately sized at 5 x 6 cm to be compatible with implantation. A completely implantable system requires the use of a transcutaneous energy transformer system (TETS) and a diagnostic telemetry system. The TETS power circuitry has been redesigned incorporating an improved, more reliable operating topography. A telemetry circuit is undergoing characterization testing. Closed loop speed control algorithms are being tested in vitro and in vivo with good success. Eleven in vivo tests were conducted with durations from 1 to 195 days. Endurance pumps have passed the 6 month interval with minimal bearing wear. All aspects of the program continue to function under formal quality assurance.

Heart-Assist Devices↗
PubMedDate not supplied

Patient survival with renal replacement therapy in heart transplantation patients.

Long-term survivors of cardiac transplantation are at risk for nephrotoxicity caused by many years of immunosuppressive therapy with cyclosporine or tacrolimus. We report on 12 patients who received heart transplants at the University of Pittsburgh, with subsequent development of end-stage renal disease (ESRD), who received renal replacement therapy at the university affiliated dialysis program. Patients were grouped by initial dialysis modality as intent to treat. Four patients were on chronic hemodialysis (HD) and eight on peritoneal dialysis (PD). Six patients died, two on HD and four on PD. There were 451 deaths per 1000 patient years for patients on PD compared with 273 deaths per 1000 patients years for patients on HD (p < 0.0001), both significantly higher than the United States Renal Data System rate of 178 per 1000 patient years for patients with ESRD who were of similar age and race, p < 0.0001. The survival rate for patients on PD seemed to be worse, but that may be because unstable patients with failing heart transplants were directed toward PD. Efforts should be made to minimize nephrotoxicity after cardiac transplantation.

Adult↗
PubMedDate not supplied

Novel ventricular apical cannula: in vitro evaluation using transparent, compliant ventricular casts.

The geometric configuration of the cannula connection to the left ventricular (LV) apex was studied with respect to several characteristics defining functionality and compatibility. The authors had previously determined, through in vivo studies in sheep, that the design of the cannula used with a dynamic blood pump for LV circulatory support can significantly affect the hemodynamics by improving both the bypass flow rate and the fluid dynamics within the ventricle. The tip of the cannula can aid in preventing wall to wall ventricular collapse, as well as septal shift, due to reduced LV pressure. Proper surgical placement of the cannula with respect to the endocardial surface of the LV can also be simplified by the tip geometry. To investigate the anatomic interaction and fluid dynamics of apical cannulation, transparent compliant casts of bovine LVs were fabricated for in vitro flow visualization. Two different heart geometries were cast, end systolic and end diastolic. The latter was fitted with a pericardial mitral valve and pressurized in a pulsatile fashion to simulate the wall movement of a beating heart. The internal flow and anatomy were visualized with fluorescent particle tracking velocimetry. These studies were performed with conventional cannula tips, as well as a novel, trumpet mouth cannula. The visualization clearly shows the dramatic differences in flow between the geometries tested, and strongly advocates a trumpet mouth design. This novel tip demonstrated excellent placement, beneficial stenting, and improved blood flow by reducing apical stasis and recirculation. Ongoing evaluation of these and future geometries include the application of in vitro endoscopy, quantitative velocimetry, and extension to dilated human ventricles.

Cardiac Catheterization↗
PubMedDate not supplied

Chronic animal health assessment during axial ventricular assistance: importance of hemorheologic parameters.

Chronic testing of the Nimbus/UOP Axial Flow Pump was performed on 22 calves for periods of implantation ranging from 27 to 226 days (average, 74 days). The following parameters were measured: plasma free hemoglobin, blood and plasma viscosity, erythrocyte deformability and mechanical fragility, oxygen delivery index (ODI), blood cell counts, hematocrit, hemoglobin, blood urea nitrogen, creatinine, bilirubin, total protein, fibrinogen, and plasma osmolality. Most of the above parameters were stable during the full course of support. Compared with baseline, statistically significant differences during the entire period of implantation were only found in: hematocrit (p<0.001), hemoglobin (p<0.005), red blood cell (RBC) count (p<0.001), and whole blood viscosity (p<0.01). Plasma viscosity and ODI were mostly stable during the period of implantation. In some animals, an acute increase in fibrinogen concentration, plasma and blood viscosity, and a decrease in ODI were found to be early signs of the onset of infection. A small (10%) decrease in deformability of RBCs was found during the first 2 weeks after implantation. This alteration in RBC deformability was highly correlated (r = 0.793) with changes in total plasma protein concentration that fell more than 15% (p<0.001) during the same period. Mechanical fragility of RBCs was found to be slightly increased after implantation. Plasma free hemoglobin remained close to baseline level (p>0.2). After the first 2 weeks of the postoperative period, pump performing parameters for all animals were consistent and stable. In general, the Nimbus/UOP Axial Flow Pump demonstrated basic reliability and biocompatibility and did not produce significant alterations in the mechanical properties of blood or animal health status. The pump provided adequate hemodynamics and was well tolerated by the experimental animal for periods as long as 7.5 months. Monitoring rheologic parameters of blood is very helpful for evaluation of health during heart-assist device application.

Animals↗
PubMedDate not supplied

Quality of life outcomes in left ventricular assist system inpatients and outpatients.

This study empirically evaluates the quality of life (QOL) effects associated with hospital discharge among heart transplant candidates whose lives are maintained by left ventricular support systems (LVAS). Thirty-five LVAS inpatients (18 Novacor, 17 Thoratec) received structured QOL assessments approximately 1 month after device implant. Ten of the patients (8 Novacor, 2 Thoratec) were subsequently discharged to either home or a home-like outpatient facility where their QOL was reassessed. The QOL of LVAS patients, before and after discharge, was compared with that of demographically similar nonhospitalized heart transplant candidates (n = 55) and recipients (n = 97). Their caregivers' QOL was also assessed. The QOL of LVAS outpatients showed statistically significant (p<0.05) advantages over remaining LVAS inpatients and nonhospitalized heart candidates. Advantages appeared in physical, emotional, and social functioning domains. The QOL of LVAS outpatients also improved (p<0.05) over their own QOL before discharge, with the greatest change in physical functional and emotional status. The QOL of LVAS outpatients most closely resembled QOL in the transplant recipients. Family caregivers to LVAS outpatients reported some increases in caregiving burden after patient discharge, but their overall well being was not adversely affected. These data provide an empiric basis for the provision of outpatient programs as appropriate care for eligible LVAS patients.

Activities of Daily Living↗
PubMedDate not supplied

Human factors issues in ventricular assist device recipients and their family caregivers.

Ultimately, for ventricular assist devices (VADs) to be acceptable as permanent alternatives to heart transplantation, patients' and their families' satisfaction with specific features and risks of VADs must be addressed. Of 42 eligible patients who received VADs between February of 1996 and December of 1998, we interviewed 37 patients (17 Novacor, 18 Thoratec, 2 with both devices) and 20 of their primary family caregivers about device related concerns and reactions. Demographic and health related correlates of respondents' concerns were examined. Eleven patients discharged from the hospital with the VAD in place were then reinterviewed 1 month after discharge. At baseline, patients' general perceptions of the VAD were positive, although 22-52% reported specific concerns, including most often worry about infection (52%), difficulty sleeping due to the position of the driveline (52%), pain at the driveline exit site (46%), worry about device malfunction (40%), and being bothered during the day by device noise (32%). The prevalence of most concerns rose with duration of VAD support. Caregivers' perceptions did not differ significantly from patients' perceptions. Outpatients were somewhat more concerned than inpatients about device noise and risk of stroke, but were markedly less concerned about infection. Across all patients, higher levels of device related concerns were correlated with more physical functional limitations and more psychological distress, and reduced quality of life. Demographic characteristics and device type were not uniformly related to device concerns.

Activities of Daily Living↗
PubMedDate not supplied

Relationship of blood pressure and pump flow in an implantable centrifugal blood pump during hypertension.

The purpose of this study was to evaluate the real time relationship between pump flow and pump differential pressure (D-P) during experimentally induced hypertension (HT). Two calves (80 and 68 kg) were implanted with the EVA-HEART centrifugal blood pump (SunMedical Technology Research Corp., Nagano, Japan) under general anesthesia. Blood pressure (BP) in diastole was increased to 100 mm Hg by norepinephrine to simulate HT. Pump flow, D-P, ECG, and BP were measured at pump speeds of 1,800, 2,100, and 2,300 rpm. All data were separated into systole and diastole, and pump flow during HT was compared with normotensive (NT) conditions at respective pump speeds. Diastolic BP was increased to 99.3+/-4.1 mm Hg from 66.5+/-4.4 mm Hg (p<0.01). D-P in systole was under 40 mm Hg (range of change was 10 to 40 mm Hg) even during HT. During NT, the average systolic pump flow volume was 60% of the total pump flow. However, during HT, the average systolic pump flow was 100% of total pump flow volume, although the pump flow volume in systole during HT decreased (33.1+/-5.7 vs. 25.9+/-4.0 ml/systole, p<0.01). In diastole, the average flow volume through the pump was 19.6+/-6.9 ml/diastole during NT and -2.2+/-11.1 ml/diastole during HT (p<0.01). The change in pump flow volume due to HT, in diastole, was greater than the change in pump flow in systole at each pump speed (p<0.001). This study suggests that the decrease of mean pump flow during HT is mainly due to the decrease of the diastolic pump flow and, to a much lesser degree, systolic pump flow.

Animals↗
PubMedDate not supplied

Prevalence and risk of depression and anxiety-related disorders during the first three years after heart transplantation.

Although poor psychological adjustment to organ transplantation appears to be a major contributor to reduced quality of life and increased physical morbidity, the prevalence and risk factors for psychiatric disorder have not been considered beyond the first 12-18 months after transplantation. The authors enrolled a representative sample of 191 heart transplant recipients in a prospective examination of the prevalence, clinical characteristics, and risk factors for DSM-III-R major depressive disorder (MDD), generalized anxiety disorder (GAD), associated adjustment disorders, and posttraumatic stress disorder related to transplant (PTSD-T) during the 3 years postsurgery. Survival analysis indicates that cumulative risks for disorder onset were MDD, 25.5%; adjustment disorders, 20.8% (17.7% with anxious mood); PTSD-T, 17.0%; and any assessed disorder, 38.3%. There was only one case of GAD. PTSD-T onset was limited almost exclusively to the first year posttransplant. Episodes of MDD (but not anxiety disorders) that occurred later posttransplant (8 to 36 months postsurgery) were more likely than early posttransplant episodes to be treated with psychotropic medications. For both MDD and anxiety disorders, later episodes were less likely to be precipitated by transplant-related stressors than other life stressors. Factors increasing cumulative risk for psychiatric disorder posttransplant included pretransplant psychiatric history, female gender, longer hospitalization, more impaired physical functional status, and lower social supports from caregiver and family in the perioperative period. Risk factors' effects were additive; the presence of an increasing number of risk factors bore a dose-response relationship to cumulative risk of disorder.

Adolescent↗
PubMedDate not supplied

Heparin effect on red blood cell aggregation.

We studied the effect of relatively high dosages of heparin (25-150 U/ml) on some rheological parameters of donor blood. It was found that heparin increased the erythrocyte sedimentation rate (ESR) and low shear blood viscosity at all concentrations studied. The increase of these parameters indicates an elevation in RBC aggregation. In all samples with a heparin concentration of 100 U/ml, the average ESR was increased by approximately 75% (p < 0.001); whole blood viscosity increased under shear rate, gamma = 0.277 sec-1, by approximately 30% (p < 0.001). Since bolus injection of heparin may result in transient high local concentration, these results suggest a possible additional adverse effect to the well known heparin effect on platelet aggregation.

Anticoagulants↗
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Nursing management and rehabilitation of chronic ventricular assist device (VAD) patients.

With the increasing number of heart transplants performed annually and the number of available organs decreasing, more patients are being bridged to transplant by mechanical circulatory support (MCS) systems during their wait for a donor organ. The duration of assistance with MCS has also increased due to this shortage of donor organs. The Artificial Heart Program at the University of Pittsburgh, recognizing this changing population, has shifted the focus of care from acute support to chronic support of VAD patients. Providing care directed at long-term support has promoted rehabilitation and helped to improve the overall bridge experience. At the University of Pittsburgh, 34 patients were implanted with MCS devices as a bridge to transplant between June 1987 and September 1992 (Figure 1). Thirteen of these patients were supported for over 60 days. Of these, three were eventually discharged to an out-of-hospital facility six blocks from the medical center. Eleven of the 13 patients supported over 60 days were discharged following successful orthotopic cardiac transplantation. In response to this increasing duration of support in the bridge to transplant patient, the role of the nurse has changed significantly. Nursing care initially focused on acute physiologic monitoring procedures that are restricted to an intensive care setting. Today the role of the MCS nurse encompasses a much broader area including medical care, education, and patient rehabilitation. It is important to realize that these aspects of care begin when a patient is identified as a MCS candidate and continue throughout the acute postoperative phase into the chronic phase of recovery.

Heart-Assist Devices↗
PubMedDate not supplied

Utility of prostaglandin E1 in the pretransplantation evaluation of heart failure patients with significant pulmonary hypertension.

Patients with chronic heart failure frequently have pulmonary hypertension. Because severe preoperative pulmonary hypertension predicts a poor outcome after orthotopic transplantation, pulmonary vasoreactivity is evaluated frequently in the pretransplantation screening of heart failure patients. We prospectively evaluated the utility of the direct pulmonary vasodilator, prostaglandin E1, and compared it to the nonspecific vasodilators, nitroglycerin and sodium nitroprusside, in the evaluation of pulmonary hypertension in 39 heart transplantation candidates. Prostaglandin E1 significantly lowered pulmonary artery pressure, transpulmonary pressure gradient, and pulmonary vascular resistance. An adequate pulmonary vasodilator response (defined as a decline in transpulmonary pressure gradient to less than 15 mm Hg) occurred in 31 patients (79%). In a subgroup of nine patients also tested with nitroglycerin, greater reductions (p less than 0.01) in both transpulmonary pressure gradient and pulmonary vascular resistance occurred with prostaglandin E1, compared to nitroglycerin. Five of six patients who did not respond to nitroglycerin responded to prostaglandin E1. In another subgroup of 12 patients who were also evaluated with sodium nitroprusside, prostaglandin E1 produced a larger decline (p less than 0.05) in transpulmonary pressure gradient and pulmonary vascular resistance than did sodium nitroprusside. Six of eight patients who did not respond to sodium nitroprusside responded to prostaglandin E1. Based on pulmonary vasodilator response to prostaglandin E1, 27 patients were accepted on the transplantation waiting list, and eight patients underwent orthotopic transplantation. Postoperatively, acute right ventricular failure of the donor heart developed in none of these patients. Significant hemodynamic improvement occurred by 24 hours and persisted through 4 weeks of postoperative follow-up in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗
PubMedDate not supplied

Cardiac events after heart transplantation: incidence and predictive value of coronary arteriography.

Cardiac events from graft arteriopathy, including myocardial infarction, heart failure resulting from previous myocardial infarction, and sudden death, may limit long-term survival after heart transplantation. To determine the incidence of cardiac events and the use of coronary arteriography in predicting these events, the long-term results (mean follow-up, 3.5 years; standard deviation +/- 2.0) of heart transplantation in 427 patients were reviewed. Cardiac events included 19 cases of myocardial infarction, 13 cases of sudden death, and 10 cases of congestive heart failure. All these events occurred after the first year except for three cases of sudden death and one case of myocardial infarction. Cumulative incidence of cardiac events per patient year was 0.9% within the first year, increasing to 1.9% by 5 years. Cardiac events accounted for 3.8% of the deaths by the end of the first year, rising to 18% of total mortality by 7 years after heart transplantation. In patients dying after the first year of transplantation, deaths from sequelae of coronary artery disease occurred in 36% (20/55). The relative risk ("odds ratio") of any cardiac event was 3.44 (p less than 0.05) in patients with angiographic evidence of obstructive disease compared with those without evidence of disease, risk of cardiac death 4.6 (p less than 0.05) and risk of sudden death, 2.4 (not significant). Of the 13 patients who died suddenly, five seen at autopsy were found to have had a recent myocardial infarction. Of all patients who died of heart disease, recent myocardial infarction was detected in nine who were seen at autopsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Cytomegalovirus infection and survival in lung transplant recipients.

Fifty-nine patients who survived more than 30 days after lung transplantation (52 heart-lung, seven double lung, and two single lung) were studied for mortality and morbidity related to cytomegalovirus (CMV) infection. CMV infection developed in 32 patients (54%) and was more common in the preoperatively CMV seropositive group (95%) as compared with the seronegative group (38%). Symptomatic infections, pneumonitis, and CMV-related mortality, however, were higher in the seronegative (primary infection) group and actuarial survival was worse in these patients (40% and 23% at 1 and 5 years, respectively). Transplantation of CMV-seropositive donor organs was associated with a significantly higher incidence of primary infection and use of seronegative blood products led to a decrease in the primary CMV infection rate. The mortality of primary CMV infection was 54% and this was associated with a significantly higher rate of pulmonary superinfections in the first year after transplantation. The incidence of late pulmonary infections was associated with the development of chronic rejection rather than CMV status. We conclude that primary CMV infection has a major impact on the outcome after lung transplantation. The high mortality of primary infections justifies an aggressive approach to prevention and treatment in the at-risk seronegative group.

Actuarial Analysis↗
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Posttransplant lymphoproliferative disease in thoracic organ transplant patients: ten years of cyclosporine-based immunosuppression.

Lymphoproliferative disease developed in 15 heart and five lung transplant recipients during a decade of heart and lung transplantation from 1980 through 1989. The overall incidence of posttransplant lymphoproliferative disease in patients who survived more than 30 days is 4%. The incidence after heart transplantation is 3.4% and after lung transplantation is 7.9% (p = 0.08). The peak occurrence of posttransplant lymphoproliferative disease is 3 to 4 months after transplantation. However, posttransplant lymphoproliferative disease occurring early versus late (defined as before or after 1 year after transplantation) appears to have different clinical outcomes. The mortality of early onset of posttransplant lymphoproliferative disease as a result of lymphoma is 36%; response to reduction in immunotherapy occurs in 89% and presentation with disseminated disease occurs in 23%. The mortality of late onset of posttransplant lymphoproliferative disease as a result of lymphoma is 70%; no patient responded to reduction in immunotherapy and presentation with disseminated disease occurs in 86% of patients. Epstein-Barr virus primary infection was present in 14 and secondary Epstein-Barr virus infection was present in three of the 20 patients with posttransplant lymphoproliferative disease. The other three patients were positive for Epstein-Barr virus also but had no pretransplant sera for comparison. There is no correlation with immunoprophylaxis or maintenance immunosuppression and the development of posttransplant lymphoproliferative disease in our series.

Cyclosporine↗
PubMedDate not supplied

Thrombin generation in cardiac device recipients.

Thrombin generation measured after LVAS (4 patients) and TAH (1 patient) implantation was found to be elevated (3 times normal) in the first postoperative week and declined to normal levels when anticoagulation was begun. Thrombin generation was not elevated at the times of thromboembolic events (TIAs; N = 4 episodes).

Heart, Artificial↗
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Univentricular support results in reduction of pulmonary resistance and improved right ventricular function.

A retrospective analysis was performed to assess the effects of univentricular support on the transpulmonary gradient (TPG), pulmonary vascular resistance (PVR), total pulmonary resistance (TPR), and right ventricular ejection fraction (RVEF) in 16 patients who spent from 2 to 144 days (mean, 61) on the Novacor left ventricular assist system ([LVAS] Novacor Corp., Baxter Healthcare, Oakland, CA) as a bridge to cardiac transplantation. Results revealed a significant reduction in the TPR, and improvement in RVEF while patients were on the LVAS. After orthotopic heart transplantation (OHTx), TPG and PVR were significantly lower than when calculated before support. It was concluded, therefore, that the reduction in the TPR and the improvement in the RVEF, seen in patients who were provided univentricular support with the Novacor LVAS, are associated with a significant reduction in the TPG and the PVR, which are persistent after OHTx. Four patients who otherwise would have been considered at higher risk for OHTx because of elevated pulmonary resistance before veniventricular support underwent successful OHTx after LVAS support.

Adolescent↗