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R L Kormos

Publications and source records attributed to R L Kormos.

At least 37 records · Page 2Linked to original sources
PubMed1999

Evaluation of the potential role of color-coded tissue Doppler echocardiography in the detection of allograft rejection in heart transplant recipients.

BACKGROUND: Color-coded tissue Doppler (TD) echocardiography can noninvasively quantify alterations in left ventricular (LV) systolic and diastolic function. The objective of this study was to test the hypothesis that TD may play a role in the detection of LV dysfunction associated with allograft rejection in heart transplant recipients. METHODS AND RESULTS: Seventy-eight consecutive transplant recipients underwent 89 TD studies of posterior wall myocardial velocity gradient and mitral annular velocity within 1 hour of endomyocardial biopsy. Color TD echocardiographic images were digitized for semiautomated computer analysis. Histologic analysis revealed no significant rejection in 75 biopsies and significant rejection in 14. TD posterior wall peak systolic and diastolic velocity gradients were reduced significantly with rejection: 3.9 +/- 2.0 s(-1) versus 2.6 +/- 0.9 s(-1) and 5.4 +/- 2. 4 s(-1) versus 3.5 +/- 1.6 s(-1), respectively (P <.05 vs the nonrejecting group). Peak systolic and diastolic mitral annular velocities by TD were also reduced with rejection: 63 +/- 14 mm/s versus 49 +/- 12.4 mm/s and 90 +/- 23 mm/s versus 60 +/- 21 mm/s, respectively (P <.001 vs the nonrejecting group). A TD peak-to-peak mitral annular velocity >135 mm/s had 93% sensitivity, 71% specificity, and 98% negative predictive value for detecting rejection. Although TD was unable to discriminate between rejection and other causes of low velocity values, high TD velocity values were supportive of excluding rejection. CONCLUSIONS: These data suggest that color-coded TD may play a potential role as a screening test to exclude rejection in heart transplant recipients. Although this method has the potential to decrease the number of biopsies, further testing in a larger series of transplant recipients with rejection is warranted.

Biopsy↗
PubMed1999

Development of the Nimbus/University of Pittsburgh innovative ventricular assist system.

BACKGROUND: Nimbus Inc, and the University of Pittsburgh's McGowan Center for Artificial Organ Development have been collaborators on rotary blood pump technology initiatives since 1992. Currently, a major focus is an innovative ventricular assist system (IVAS) that features an implantable, electrically powered axial flow blood pump. In addition to the blood pump, a major development item is the electronic controller and the control algorithm for modulating pump speed in response to varying physical demand. METHODS: Methods used in developing the IVAS include computational fluid dynamic modeling of the pump's interior flow field, flow visualization of the flow field using laser-based imaging, computer simulation of blood pump-physiological interactions, vibroaccoustic monitoring, and an extensive in vivo test program. RESULTS: Results to date, which are presented below, include successful in vivo tests of blood pumps with blood-immersed bearings, and feasibility demonstration of vibroacoustic monitoring in this application. CONCLUSIONS: This unique blend of industrial experience and technologies with the University-based Research and Development Center has greatly enhanced the progress made on this IVAS project.

Animals↗
PubMed1999

Early post-transplant medical compliance and mental health predict physical morbidity and mortality one to three years after heart transplantation.

BACKGROUND: Poor medical compliance has been held responsible for a large proportion of deaths occurring subsequent to initial postoperative recovery. However, beyond clinical reports, there has been little empirical examination of this issue, or of the extent to which major psychiatric disorder and failure to adjust to the transplant predict long-term physical morbidity and mortality. We prospectively examined whether a full range of compliance behaviors and psychiatric outcomes during the first year post-transplant predicted subsequent mortality and physical morbidity through 3 years post-transplant. METHODS: A total of 145 heart recipients who had received detailed compliance and mental health assessments during the first year post-transplant were followed up at 3 years post-transplant. Interview data and corroborative information from family members were used to determine compliance in multiple domains, psychiatric diagnoses, and psychiatric symptomatology during the first year post-surgery. Medical record reviews were performed to abstract data on acute graft rejection episodes, incident cardiac allograft disease (CAD) and mortality from 1 to 3 years post-transplant. RESULTS: After controlling for known transplant-related predictors of outcome, multivariate analyses yielded the following significant (p < 0.05) results: (a) risk of acute graft rejection was 4.17 times greater among recipients who were not compliant with medications; (b) risk of incident CAD was elevated by persistent depression (Odds Ratio, OR = 4.67), persistent anger-hostility (OR = 8.00), medication noncompliance (OR = 6.91), and obesity (OR = 9.92); and (c) risk of mortality was increased if recipients met criteria for Post-Traumatic Stress Disorder related to the transplant (OR = 13.74). CONCLUSIONS: The findings, plus data we have previously reported that showed which patients are most likely to have compliance and psychiatric problems early post-transplant, suggest that interventions focused on maximizing patients' psychosocial status in these areas may further improve long-term physical health outcomes in this population.

Adult↗
PubMed1999

Native heart complications after heterotopic heart transplantation: insight into the potential risk of left ventricular assist device.

BACKGROUND: In heterotopic heart transplantation, the donor heart is connected parallel to the recipient's diseased heart. Recipients continue to have risks, such as arrhythmia, thromboembolism, valvular heart disease, and ischemic heart disease which can develop in the native heart. It may serve as a clinical model to study long-term pathophysiologic processes in the native heart of patients with a left ventricular assist device. METHOD: We analyzed the prevalence of long-term complications related to the native heart in the heterotopic heart transplant and attempted to gain insight into the potential risk to a native heart after receiving a left ventricular assist device. RESULTS: Between December 1984 and December 1994, 16 patients (13 men, 3 women, ranging in age from 37 to 60 years) underwent heterotopic heart transplant at the University of Pittsburgh. The 1- and 5-year survival rate after the transplant was 81% and 44%, respectively. Actuarial freedom from complications related to the native heart after 1 year and 4 years was ventricular arrhythmia: 85%, 75%; ischemic disease: 85%, 64%; valvular disease: 100%, 88%; and thromboembolism: 85%, 58%. Of these complications, thromboembolism was not considered in determining actuarial freedom from complications because thromboembolism should be regarded as a device-related complication rather than as a native-heart-related complication for left ventricular assist device recipients. Consequently, actuarial freedom from all complications excluding thromboembolism was 70% after 1 year and 50% after 4 years. In addition, the hazard function curve remains constant up to 80 months after the operation without significant differences among the yearly ratios. CONCLUSIONS: This analysis suggests that cautious observation of the native heart's long-term performance is necessary for the left ventricular assist device recipient.

Adult↗
PubMed1999

Rotary blood pump flow spontaneously increases during exercise under constant pump speed: results of a chronic study.

Many types of rotary blood pumps and pump control methods have recently been developed with the goal of clinical use. From experiments, we know that pump flow spontaneously increases during exercise without changing pump control parameters. The purpose of this study was to determine the hemodynamics associated with the long-term observation of calves implanted with centrifugal blood pumps (EVAHEART, Sun Medical Technology Research Corporation, Nagano, Japan). Two healthy female Jersey calves were implanted with devices in the left thoracic cavity. A total of 22 treadmill exercise tests were performed after the 50th postoperative day. During exercise, the following parameters were compared with conditions at rest: heart rate, blood pressure, central venous oxygen saturation (SvO2), pump speed, and pump flow. The pump flow in a cardiac cycle was analyzed by separating the systole and diastole. Compared to the base data, statistically significant differences were found in the following interrelated parameters: the heart rate (66.8 +/- 5.2 vs. 106 +/- 9.7 bpm), mean pump flow (4.8 +/- 0.2 vs. 7.0 +/- 0.3 L/min), and volume of pump flow in diastole (26.0 +/- 1.8 vs. 13.5 +/- 2.5 ml). During exercise, the volume of pump flow in systole was 3 times larger than that measured in diastole. Blood pressure, SvO2, and pump speed did not change significantly from rest to exercise. These results suggested that the mean pump flow depends on the systolic pump flow. Therefore, the increase in the mean pump flow during exercise under constant pump speed was caused by an increase in the heart rate.

Animals↗
PubMed1999

Measurement of hemostatic indexes in conjunction with transcranial doppler sonography in patients with ventricular assist devices.

BACKGROUND AND PURPOSE: Clinical thromboembolism (TE) remains an impediment to the chronic application of ventricular assist devices (VADs). Microembolic signals (MES) have been detected by transcranial Doppler ultrasound (TCD) in patients with VADs, although their origin and relation to TE remain undefined. We have investigated the hypothesis that hemostatic alterations are related to MES and that MES are associated with TE in a group of 27 VAD patients. METHODS: Indexes of coagulation, fibrinolysis, and cellular activation and aggregation were measured before and during the VAD implantation period in conjunction with TCD. Groups were defined on the basis of presence of MES, degree of MES showering, and incidence of TE. RESULTS: MES were observed in 67 (58%) of 115 of individual postoperative TCD measurements and in 21 (78%) of 27 patients. Of patients with TE, 10 (83%) of 12 had detectable MES compared with 11 (73%) of 15 patients without TE (P=0.66). MES were significantly associated with elevated thrombin generation during the implantation period, as reflected by plasma prothrombin fragment F1.2. Elevations in indexes of coagulation, platelet activation, and fibrinolysis relative to normal control subjects were found for patients with VADs with and without detected MES. CONCLUSIONS: Although no significant relation between MES and TE in VAD patients was found, the data support the hypothesis that MES are related to increased hemostatic activity in this patient group despite aggressive anticoagulant therapy.

Adolescent↗
PubMed1998

Heterogeneous immediate effects of partial left ventriculectomy on cardiac performance.

BACKGROUND: Partial left ventriculectomy (PLV) is a novel surgical treatment for severe heart failure consisting of resection of a large wedge of myocardium to reduce wall stress and restore the normal mass-volume ratio. Although ejection fraction (EF) has been shown to improve after PLV, few other physiological data describing its immediate effects on left ventricular (LV) performance are available. METHODS AND RESULTS: Eight patients, 58+/-5 years old, with severe clinical heart failure and EF of 12+/-3% were studied before and immediately after PLV. LV performance was assessed by the predominantly load-insensitive measures of pressure-area relations with high-fidelity pressure catheters and transesophageal automated echocardiographic measures of cross-sectional area as a surrogate for volume. LV end-diastolic volume decreased from 200+/-60 to 89+/-17 mL, EF increased from 12+/-3% to 41+/-8%, and right ventricular (RV) fractional area change increased from 24+/-12% to 37+/-16% (all P<.05 versus before). Changes in pressure-area relations were variable: end-systolic elastance, 6.5+/-3.4 to 4.3+/-2.5 mm Hg/cm2 and preload recruitable stroke work, 33+/-16 to 34+/-19 mm Hg (P=NS versus before). End-diastolic stiffness increased from 0.13+/-0.06 to 0.19+/-0.07 mm Hg/cm2 (P<.05 versus before). Improvement in LV performance was inversely correlated with semiquantitative histological assessment of myocardial fibrosis and positively correlated with nuclear enlargement and hyperchromasia, indicative of myocyte hypertrophy. No long-term follow-up data were available. CONCLUSIONS: PLV resulted in reductions in LV volumes, increases in EF and RV ejection, but increases in LV stiffness. Estimates of LV performance revealed variable results associated with the degree of myocardial fibrosis. Further study of these effects in relation to patient outcome is warranted.

Aged↗
PubMed1998

Abciximab and excessive bleeding in patients undergoing emergency cardiac operations.

BACKGROUND: Abciximab (ReoPro; Eli Lilly and Co, Indianapolis, IN) is a monoclonal antibody that binds to the platelet glycoprotein IIb/IIIa receptor and produces powerful inhibition of platelet function. Clinical trials of abciximab in patients undergoing coronary angioplasty have demonstrated a reduction in thrombotic complications and have encouraged the widespread use of this agent. We have observed a substantial incidence of excessive bleeding among patients who receive abciximab and subsequently require emergency cardiac operations. METHODS: The records of 11 consecutive patients who required emergency cardiac operations after administration of abciximab and failed angioplasty or stent placement were reviewed. RESULTS: The interval from the cessation of abciximab administration to operation was critical in determining the degree of coagulopathy after cardiopulmonary bypass. The median values for postoperative chest drainage (1,300 versus 400 mL; p < 0.01), packed red blood cells transfused (6 versus 0 U; p = 0.02), platelets transfused (20 versus 0 packs; p = 0.02), and maximum activated clotting time (800 versus 528 seconds; p = 0.01) all were significantly greater in the early group (cardiac operation < 12 hours after abciximab administration; n = 6) compared with the late (cardiac operation >12 hours after abciximab administration; n = 5) group. CONCLUSIONS: This report suggests that the antiplatelet agent abciximab is associated with substantial bleeding when it is administered within 12 hours of operation.

Abciximab↗
PubMed1998

Monocyte tissue factor expression and ongoing complement generation in ventricular assist device patients.

BACKGROUND: Ongoing complement activation in patients with a ventricular assist device may contribute to observed hemostatic abnormalities and cellular aggregation by mediating leukocyte and platelet activation, formation of leukocyte-platelet conjugates, and the tissue factor pathway of coagulation. METHODS: Blood from 30 patients was collected before ventricular assist device implantation and during the implantation period. Plasma levels of thrombin-antithrombin III complexes, C3a, and SC5b-9 were measured by commercial enzyme-linked immunosorbent assay. Flow cytometry was used to measure circulating monocyte tissue factor expression and circulating monocyteplatelet and granulocyte-platelet conjugates. RESULTS: Thrombin-antithrombin III complex level and monocyte tissue factor expression peaked in the early postoperative period, with maxima occurring on postoperative days 5 and 3, respectively. Levels of C3a and SC5b-9 remained dramatically elevated over normal values for the duration of the study (6 and 5 times upper normal, respectively). Levels of monocyte-platelet conjugates were normal before implantation, decreased during the first 4 postoperative days, and then increased and remained elevated. Levels of granulocyte-platelet conjugates were elevated over the normal range before implantation and remained elevated from postoperative days 3 to 21. A positive correlation was found between levels of SC5b-9 and granulocyte-platelet conjugates (Spearman R=0.66; p < 0.001), and between levels of C3a and thrombin-antithrombin III complex (Spearman R=0.13; p=0.021). CONCLUSIONS: The data suggest a model in which complement mediates formation of leukocyte-platelet aggregates and may indirectly contribute to thrombin generation through monocyte tissue factor expression.

Adult↗
PubMed1998

Traumatic aortic rupture: diagnosis and management.

BACKGROUND: Traumatic aortic rupture is a relatively uncommon lesion that presents the cardiothoracic surgeon with unique challenges in diagnosis and management. To address controversial aspects of this disease, we reviewed our experience. METHODS: The study was performed by retrospective chart review. RESULTS: Forty-two patients with traumatic thoracic aortic ruptures were managed between January 1988 and June 1997. Nine arrived without vital signs and died in the emergency department. Admission chest radiographs were normal in 3 patients (12%) and caused significant delays in diagnosis. Four of 30 patients admitted with vital signs had rupture before thoracotomy and died. Twenty-six underwent aortic repair. In 1 patient repair was performed with simple aortic cross-clamping, whereas a second was managed with a Gott shunt. The remaining 24 patients had repair with partial left heart bypass. In 1 patient hypothermic circulatory arrest was required. Two patients (7.7%) died. There were no cases of new postoperative paraplegia in the bypass group. There was no morbidity directly attributable to the administration of heparin for cardiopulmonary bypass. CONCLUSIONS: In a discrete group of patients with traumatic rupture of the aorta, the rupture will become complete during the first few hours of hospital admission; aggressive medical treatment with beta-blockade and vasodilators in the interval before the operation is an essential aspect of management. Active distal circulatory support with partial left-heart bypass provides the optimal means of preventing spinal cord ischemia during repair of acute traumatic aortic rupture.

Adult↗
PubMed1998

The CardioWest total artificial heart bridge to transplantation: 1993 to 1996 national trial.

BACKGROUND: We performed a controlled study of a total artificial heart in bridge to transplantation. We hypothesized that the CardioWest total artificial heart used in a selected population of decompensating cardiac transplantation candidates would result in improved survival compared with matched controls. METHODS: The CardioWest trial started in 1993 in six United States institutions under an investigational device exemption from the Food and Drug Administration. Four centers contributed 27 implant and 18 matched retrospective control patients. RESULTS: Of the implant patients, 25 (93%) received a transplant, 24 (89% of the total, 96% of those transplanted) were discharged and are currently surviving. In the control group, 10 patients died awaiting transplantation, 8 received a transplant, and 7 were discharged with 6 surviving (p = 0.00001). All adverse events were documented with respect to time. Thirteen serious adverse events occurred, 11 of which occurred in the 2 patients that died during implant. CONCLUSIONS: In a selected group of patients with endstage heart disease, use of the CardioWest total artificial heart is lifesaving. When compared with the series of matched retrospective controls, a significant improvement in survival was found in the CardioWest implant group.

Adolescent↗
PubMed1998

Predicting short-term outcome in severely ill heart failure patients: implications regarding listing for urgent cardiac transplantation and patient selection for temporary ventricular assist device support.

BACKGROUND: The purpose of this study was to determine which patients on a cardiac transplantation list required a ventricular assist device. METHODS AND RESULTS: In a preliminary study, 26 patients with decompensated severe New York Heart Association class IV chronic heart failure were studied. Blood levels for sodium, hemoglobin, cytokines, neurohormones, and hemodynamics were obtained. During short-term follow-up of 40 days, 12 patients had undergone emergent implantation of a ventricular assist device (range 1-27 days, mean 5 days), 4 died (range 14-38 days, mean 26 days), and 5 were alive and receiving only medical therapy while waiting for a transplantation. In addition, five patients had undergone transplantation (range 5-29 days, mean 18 days, excluded from further analysis). Survival curves were constructed by comparing the incidence of death and the implantation of an emergent ventricular assist device in patients with values of a variable above or below the mean value (or median for nonnormally distributed data). There was a significantly greater incidence of death or need for a ventricular assist device in patients with higher levels of tumor necrosis factor-alpha (P = .008), lower levels of serum sodium and hemoglobin (P = .02 and P = .03, respectively), higher heart rates (P = .03), and higher plasma norepinephrine levels (P = .01). The Cox proportional hazards model demonstrated that only serum sodium (P = .03) independently predicted those patients who died or who required emergent left ventricular assist device. CONCLUSION: Numerous variables, particularly serum sodium, need to be considered when evaluating which patients on the transplant list require early assist device implantation or urgent transplantation. These preliminary observations merit confirmation in a larger patient population.

Adult↗
PubMed1998

Fine trabecularized carbon: ideal material and texture for percutaneous device system of permanent left ventricular assist device.

The development of a percutaneous artificial internal organ system requires a reliable biocompatible connection between the external environment and the inside of the human body. Such is necessary for the success of a permanent left ventricular assist device. However, the search for a satisfactory interface at the epidermal level has proven to be difficult. Carbon has been proposed for this application, but its texture does not typically promote ingrowth from surrounding tissue. We have therefore employed a new processing method to produce a fine trabecularized carbon implant. The method for preparing the implant involves infiltrating low temperature pyrolytic carbon into the surface of a carbon core which is wrapped with carbon fabric. This results in a tightly woven porous structure of carbon (carbon fiber diameter: 35-50 microm, maximal pore size >200 microm) with gradually increasing porosity from 15-75%. We implanted test samples percutaneously in a calf for in vivo histological evaluation. Thirty days after implantation epidermal downgrowth was minimal. Microscopic analysis revealed that a thin fibrous capsule surrounded the implant, and mature connective tissue with accompanying blood vessels filled the pores of the fine trabecularized carbon layer. From these results we suggest that fine trabecularized carbon is ideally suited for a percutaneous device system in a permanent left ventricular assist device.

Animals↗
PubMed1998

An implantable centrifugal blood pump with a recirculating purge system (Cool-Seal system).

A compact centrifugal blood pump has been developed as an implantable left ventricular assist system. The impeller diameter is 40 mm, and pump dimensions are 55 x 64 mm. This first prototype, fabricated from titanium alloy, resulted in a pump weight of 400 g including a brushless DC motor. The weight of a second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon (DLC) to improve blood compatibility. Flow rates of over 7 L/min against 100 mm Hg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system (Cool-Seal) is used for the shaft seal. In this seal system, the seal temperature is kept under 40 degrees C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. Purge fluid is continuously purified and sterilized by an ultrafiltration unit which is incorporated in the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 +/- 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular (LV) apex descending aorta bypass was performed utilizing an expanded polytetrafluoroethylene (ePTFE) vascular graft with the pump placed in the left thoracic cavity. In 2 in vivo experiments, the pump flow rate was maintained at 5-9 L/min, and pump power consumption remained stable at 9-10 W. All plasma free Hb levels were measured at less than 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (<0.5 ml/day). In both calves, the pumps demonstrated trouble free continuous function over 6 month (200 days and 222 days).

Alloys↗
PubMed1998

Effect of pressure-flow relationship of centrifugal pump on in vivo hemodynamics: a consideration for design.

We have been developing centrifugal pumps for an implantable left ventricular assist device. We manufactured 2 prototype centrifugal pumps (PI, PII). These two have similar designs except for the PII having a volute casing and a large output port. To determine the differences in the hydraulic characteristics between the PI and PII, we carried out in vitro and in vivo experiments. In vitro study showed that the PII had a shallower H-Q curve than that of the PI, and the PII required a pump speed faster than the PI for the same flow rate and pressure head. On the other hand, in vivo study showed that the PII demonstrated a flow pulsatility greater than that of the PI at 1,900 rpm and 8 L/min although no significant change was observed at low pump speeds (< or = 1,500 rpm). This greater pulsatility consisted of a large discharge according to the small differential pressure during the systolic phase and a small discharge according to the large differential pressure during the diastolic phase. In contrast, the PI, having the steeper H-Q curve, showed a small discharge in the systolic phase and a large discharge in the diastolic phase. These results showed that pulsatility synchronized with the native heart beating depended on the slope of the H-Q curve. As a result, the slope of the H-Q curve is important to determine the component of pulsatility synchronized with native cardiac output. Regarding the slope of the H-Q curve, a pump having a volute casing and a large outlet port demonstrates a shallow slope in the H-Q curve. In conclusion, we suggest that a centrifugal pump for use in left ventricular aortic bypass should be designed considering the effect on the native heart pulsatility.

Animals↗
PubMed1997

Does transplantation produce quality of life benefits? A quantitative analysis of the literature.

BACKGROUND: Despite numerous reports published since the early 1970s, it is frequently asserted that quality of life (QOL) outcomes of transplantation have seldom been investigated and/or that little is known about QOL. This view may have persisted due to lack of adequate cumulation and synthesis of existing data. We performed an exhaustive, quantitative literature review to determine the nature and degree of any QOL benefits associated with transplantation in adults. METHODS: All independent, peer-reviewed empirical, English-language QOL studies were retrieved for six areas of transplantation: kidney, pancreas/combined kidney-pancreas, heart, lung/combined heart-lung, liver, and bone marrow. Studies' findings were analyzed to determine whether the weight of evidence suggested that (a) QOL improved from pre- to posttransplant, (b) transplant recipient QOL was better than that of patient comparison groups, and (c) recipient QOL equaled that of healthy nonpatient samples. RESULTS: A total of 218 independent studies, evaluating a total of approximately 14,750 patients, were identified. The majority of studies demonstrated statistically significant (P<0.05) pre- to posttransplant improvements in physical functional QOL, mental health/cognitive status, social functioning, and overall QOL perceptions. The majority documented physical functional and global QOL advantages for transplant recipients relative to ill comparison groups. The studies did not indicate that recipient QOL in specific functional areas equaled that of healthy, nonpatient cohorts, although global QOL perceptions were often high. CONCLUSIONS: Although transplantation may not restore to the patient the "normal" life he/she may once have had, convergent evidence from six areas of transplantation, a variety of study designs, and demographically diverse study cohorts suggests that there are distinct QOL benefits of transplantation. Future work is required to identify background and personal factors that influence the degree of QOL benefits that any individual patient realizes from transplantation.

Adult↗