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Biomedical subjects

O H Frazier

Publications and source records attributed to O H Frazier.

At least 451 records · Page 25Linked to original sources
PubMedDate not supplied

Heterotopic heart transplantation: a reliable option for a select group of high-risk patients.

From July 1982 through February 1988, 229 patients underwent heart transplantations at the Texas Heart Institute, Houston, 11 of whom had heterotopic transplantations. Indications for the heterotopic procedure included pulmonary hypertension (eight patients) and marked body-weight mismatch (greater than or equal to 20%) between the recipient and donor (three patients). The 1-year actuarial survival rate for the heterotopic group is 80.4% compared with 77.9% for the orthotopic group. Despite similar immunosuppressive regimens, the incidence of advanced rejection within 60 days after transplantation was 9.1% (one of 11 patients) for the heterotopic patients and 33.7% (68 of 202 patients) for the orthotopic group. The one heterotopic patient who experienced rejection in this period had a positive retrospective lymphocyte crossmatch. Seven patients who had heterotopic heart transplantations had right pleural effusions; three of these required tube thoracotomy. Two others experienced angina of the native heart, but the symptoms abated with cessation of native heart function. Despite anticoagulant therapy, one patient had reversible neurologic events caused by emboli. Some of the patients had pulmonary and embolic complications, but all of these problems were readily manageable and resolved without permanent sequelae. In orthotopic transplantation, the presence of pulmonary hypertension can compromise donor heart function in the intraoperative or immediate postoperative periods. Patients with this problem, previously considered unsuitable candidates for transplantation, may have a successful transplantation with the heterotopic technique. Although heterotopic heart transplantation is technically more demanding and may be associated with complications that do not occur in orthotopic transplantation, our experience has shown that it is a reliable surgical option for these high-risk patients.

Adult↗
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Nine year experience with the clinical use of total artificial hearts as cardiac support devices.

One hundred sixteen total artificial hearts (TAH) were implanted in 113 patients by 29 centers between April 4, 1969 and March 1, 1988. Five were permanent and 111 were temporary implants (3 patients received second implants). Eight different types of TAHs have been used. The ages ranged from 15 to 62 (mean age: permanent 57, temporary 42). Sixty-seven percent (72/108) of patients receiving the TAH for temporary support were transplanted; 6 patients were waiting for a transplant. Forty-seven percent (34/72) were alive after transplantation. Of the 92 patients receiving the Jarvik TAH (the most frequently used device) as a temporary device, 67% (62/92) were transplanted (6 currently supported) and 55% were alive after transplantation; 85% were back to work, with a normal life-style. The thromboembolic rate for patients who received the device as a temporary support was 10%, with 3 patients having residual sequellae. No deaths resulted from mechanical failure. Experience to date suggests that the use of the TAH as a temporary device can be beneficial if patients are carefully selected.

Adolescent↗
PubMedDate not supplied

Treatment of moderate heart allograft rejection with cyclosporine.

In the management of heart transplant patients, treatment of acute rejection, as diagnosed by means of endomyocardial biopsy, is critical. Standard antirejection agents include corticosteroids, antithymocyte globulin, and orthoclone. In addition to these drugs, we used increased dosages of cyclosporine to treat 27 episodes of moderate allograft rejection in 24 patients. To qualify for inclusion in this study, patients could not show signs of cyclosporine toxicity despite normal (200 to 300 ng/ml) or high cyclosporine levels and clinical signs of rejection. Therapy consisted of increased oral dosages of up to 14 mg/kg/day of cyclosporine in addition to 1 to 3 mg/kg/day of intravenous cyclosporine. In all 24 patients high levels of cyclosporine were maintained until signs of toxicity appeared, at which point the dosage was adjusted. If endomyocardial biopsy indicated improvement, the dosage was readjusted to maintain cyclosporine levels between 200 and 300 ng/ml. Treatment was successful in 22 cases (81.5%). We compared this group of patients with a not randomly selected but time-overlapping group of 32 patients, who received a steroid pulse for moderate allograft rejection. The incidence of infectious episodes was significantly lower in the cyclosporine-treated patients than in patients given a steroid pulse. There were no signs of permanent kidney or liver damage during or after treatment with increased dosages of cyclosporine. Therefore we conclude that increased dosages of cyclosporine are safe and effective in treating moderate allograft rejection.

Adult↗
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Heterotopic heart-single lung transplantation: report of a new technique.

A new surgical technique for patients with end-stage pulmonary and cardiopulmonary disease is described. This technique, a heterotopic heart-single lung transplant, limits dissection in the vascular collateralized mediastinum and preserves the carina and left lung. Moreover, it preserves the recipient's heart when the predominant problem is pulmonary. We used this technique in a 34-year-old woman with end-stage cardiopulmonary disease, resulting from pulmonary hypertension, who was referred to the Texas Heart Institute for evaluation as a candidate for a heart-lung transplantation. She had undergone ligation of a large hypertensive patent ductus arteriosus in early childhood. We believe our technique is a potentially viable alternative for selected heart-lung transplant patients.

Adult↗
PubMedDate not supplied

In vivo evaluation of a peripheral vascular access axial flow blood pump.

More than 80 acute and chronic calf in vivo studies were utilized to develop a 3 L/min axial flow blood pump designed for intraarterial ventricular assist. The 7 mm diameter transvalvular inlet cannula of the cable driven pump receives blood from the left ventricle. The pump then discharges blood into the descending aorta. In the calf, the pump was introduced into the renal aorta. Safety and effectiveness of the device were demonstrated in three control and 21 implanted animals. Blood chemistry results showed an average plasma free hemoglobin of 3 mg/dl for control and 6.7 mg/dl for implanted animals. Platelets were 1.04 X 10(6) and 0.65 X 10(6), respectively, for control and implanted animals. Fibrinogen, BUN, creatinine, and bilirubin were essentially the same for both groups of animals. The hardware was typically free of deposits, and histopathologic examination revealed minimal injury to intracardiac structures, aortic valve leaflets, and aortic intima. The data indicates that the device may provide full support for a failing left ventricle with minimal trauma or risk.

Animals↗
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Simplified method of hemofiltration in ventricular assist device patients.

Hypervolemia frequently complicates the management of ventricular assist device (VAD) patients as a result of increased intravenous fluid administration and concomitant renal dysfunction. Although acute hemodialysis (AHD) can be used to treat such patients, it requires additional equipment, vascular access cannulations, and personnel. Moreover, hypotension during AHD may occur as a result of rapid shifts in intravascular volume. From January 1987 to March 1988, we treated nine selected VAD patients who had hypervolemia and acute renal failure with a simplified hemofiltration technique. A continuous arteriovenous hemofiltration (CAVH) cartridge was connected from the outflow circuit of a centrifugal blood pump to a large-bore central venous catheter. With CAVH, gradual removal of 272 cc/hour of ultrafiltrate was accomplished for periods up to 241 hours. No episodes of hypotension, thromboembolism, or other deleterious effects occurred. In our series, the CAVH technique was effective in treating hypervolemia in selected VAD patients.

Acute Kidney Injury↗
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Comparative in vitro evaluations of vascular graft compliance during dynamic loading.

A prosthetic vascular graft should be nonthrombogenic, compliant with anastomosed vessels and resist excessive dilatation or aneurysm formation. Mechanical performance of a negatively charged, glutaraldehyde-tanned bovine heterograft was evaluated, in vitro, during dynamic loading conditions. The grafts were 16 cm in length with internal diameters of 6 mm (n = 10), 8 mm (n = 12), and 10 mm (n = 8). The prostheses were pneumatically cycled, using intragraft balloons, at a pulse pressure of 120/70 mmHg and a rate of 80 beats/min in 37 degrees C saline for 2.6 million cycles (22.6 days). At selected intervals, the diastolic and pulse volumes of the grafts were measured and compliance calculated. These studies demonstrated that this vascular prosthesis had a high initial compliance, independent of graft diameter. During dynamic loading, diastolic volume increased whereas pulse volume and compliance decreased 12%, 43%, and 49%, respectively (P less than 0.001). Greater than 75% of the changes occurred within 5 days after the onset of testing. Despite these changes, isocompliance was demonstrated for the BioPolyMeric grafts following 22 days of cycling, yielding values similar to those reported for human saphenous vein.

Animals↗
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Summary of the world experience with clinical use of total artificial hearts as heart support devices.

A review of the world experience with the implantation of total artificial hearts has been carried out. Thirteen centers throughout the world have implanted 27 total artificial hearts in 26 patients. Eight different types of total artificial hearts have been employed. As of June 1, 1986, five of these individuals have had implants for permanent support. Of the other twenty-one patients, three patients died while on a total artificial heart, seven patients died following transplantation, two patients are waiting for transplant, and nine patients have successfully been transplanted and are presently alive. Various clinical preoperative and postoperative parameters are analyzed in this investigation.

Adult↗
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Surgical positioning of the Jarvik-7 artificial heart.

The Jarvik-7 total artificial heart has been implanted in 18 patients at the time of this writing. Eleven patients received the 100 ml heart, and the remaining seven were treated with the 70 ml device. To date, five patients have been implanted for permanent use with an average survival in excess of 9 months, and the longest survival is more than 1 1/2 years following implantation of the heart. Complications related to positioning were a contributing factor in the death of one patient. Thirteen patients have received the Jarvik-7 heart as a bridge to transplant. Three died before transplant, and the remaining ten have been transplanted. To date, all are alive, several are home and in excellent condition, and several are still hospitalized but are expected to be released shortly. Three patients have experienced serious complications after transplantation. One patient rejected her heart transplant, was reimplanted with the artificial heart, and now has been sustained for more than 3 months. At this time she is in good condition awaiting a second donor. Selection of the appropriate size Jarvik-7 artificial heart for the individual patient can best be made based on measurements of thoracic dimensions obtained from a computed tomography scan and calculation of body surface area. The appropriate medial or lateral positioning can be determined and decisions concerning the lengths of the grafts and cuffs, excision or nonexcision of the left pericardium, and air drive line position can be made. The Jarvik-7 heart can be successfully used in patients from 50 kg. However, at the lower size limit in patients from approximately 50 to 65 kg, the risk of fit complications is the greatest and availability of an even smaller model heart would be desirable.

Adult↗
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Replacement of the left ventricle with a single-chambered artificial pump.

Early clinical experience with total artificial hearts has stimulated further research and interest in this field. The concept of total heart replacement with a permanent mechanical device has been reevaluated, and its application as a bridge to heart transplantation is becoming more widely accepted. The size of total artificial hearts, however, limits the number of cases in which they can be used. In an effort to solve this problem, we evaluated a single-ventricle artificial pump in six Hereford calves. During surgery, the left ventricle was excised and replaced with a pneumatically actuated polyurethane pump connected to the mitral and aortic valve anulus. The right ventricle provided flow through the pulmonary vasculature, which eliminated the necessity of maintaining elevated right-sided filling pressures. The single-ventricle pump required less space than a biventricular device and was capable of maintaining adequate hemodynamic parameters in experimental animals. In comparison with the biventricular pump, this device offered the advantages of less extensive dissection requirements, ease of anastomosis, and a better anatomic fit. Patients whose pericardial cavities are too small for a biventricular artificial heart may benefit from the single-ventricle pump if they require hemodynamic support while awaiting heart transplantation.

Animals↗
PubMedDate not supplied

Nutritional management of the heart transplant recipient.

From July 1982 through February 1985, 52 patients underwent an orthotopic heart transplantation at the Texas Heart Institute. Immunosuppressive therapy consisted of cyclosporine and corticosteroids. Compromised preoperative nutritional status did not preclude acceptance into the heart transplant program. However, nutritional assessment provided a means of identifying patients who may benefit from preoperative nutritional support. The goal of postoperative nutritional therapy was to provide adequate nutrients to promote rapid wound healing and minimize complications associated with suboptimal nutritional status.

Female↗
PubMedDate not supplied

Evaluation of chronic renal disease in heart transplant recipients: importance of pretransplantation native kidney histologic evaluation.

Although long-term use of cyclosporine has been implicated in the pathogenesis of arteriolar hyalinosis, interstitial fibrosis, and glomerulosclerosis observed in the native kidneys of heart transplant recipients, it is not clear that these histologic abnormalities are entirely specific for a drug-induced toxic nephropathy. The purpose of this study was to determine whether long-standing congestive heart failure, particularly when complicated by disease processes such as atherosclerosis and hypertension, may independently predispose to the development of similar renal histopathology. Records and specimens were selected from autopsy files for evaluation of clinical profiles and kidney histology in 16 patients who died of end-stage cardiomyopathy of varying causes without having recourse to heart transplantation. The study cohort consisted of 12 men and four women. Cardiomyopathies were the result of coronary artery disease in six patients and nonischemic causes in the other 10 patients. The mean age at the time of death was 53 +/- 3 years (range 28 to 74 years). Thirteen (81%) of 16 patients had a history of hypertension. Nadir serum creatinine concentrations during the month before death were 1.7 +/- 0.2 mg/dl (range 1.2 to 3.5 mg/dl). Interstitial fibrosis, tubular atrophy, and glomerulosclerosis were present in 15 (94%) of 16 patients. Arteriosclerosis and arteriolosclerosis were found in 13 (81%) of 16 and 14 (88%) of 16 patients, respectively. A nodular pattern of arteriolar hyalinosis was observed in two patients with ischemic disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
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Flail tricuspid leaflet after multiple biopsies following orthotopic heart transplantation: echocardiographic and hemodynamic correlation.

Flail tricuspid leaflet has been reported as a relatively uncommon complication of endomyocardial biopsy in orthotopic heart transplant recipients. However, the relationship of this complication to the number of biopsies performed and to the site of access for biopsy is not known. The objectives of this study were to assess the prevalence of flail tricuspid leaflet/torn chordae tendineae in our recent transplant population, define the relationship of this complication to endomyocardial biopsy, and to correlate echocardiographic assessments of tricuspid regurgitation severity with hemodynamic data obtained at cardiac catheterization. From January 1991 to March 1993, 181 patients who had undergone orthotopic heart transplantation at our institution were evaluated with echocardiography for the presence of a flail leaflet or torn chordae tendineae of the tricuspid valve and tricuspid regurgitation. After identifying this complication in patients, we reviewed their hemodynamic tracings and biopsy protocols from the catheterization laboratory. The hemodynamic tracing chosen was that which was done at the time the flail leaflet was first diagnosed. Of the 181 patients, 21 (11.6%) had flail leaflet or torn chordae tendineae of the tricuspid valve. The group comprised 18 male and 3 female patients. The mean duration from the time of transplantation was 42 months (range, 1 to 87 months). The mean number of biopsies performed per patient was 15.5 (range, 2 to 27). The mean severity of tricuspid regurgitation by echocardiography was grade 3 (moderate); seven patients (33%) had severe regurgitation. The mean right atrial v wave by catheterization was 15 mm Hg (range, 6 to 26 mm Hg).(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Function, Right↗
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An atrial hydraulic shunt in a total artificial heart. A balance mechanism for the bronchial shunt.

An implantable TAH must be able to maintain physiologic atrial pressures over a range of left side shunt flows, which in humans can range up to 5% of the total cardiac output (CO). The authors describe the characteristics of an atrial hydraulic shunt in an electrohydraulic TAH. A small (10 cc stroke) chamber placed in line between the left atrial cuff and the inflow valve is shunted to the right hydraulic chamber. High left atrial pressure increases the volume displaced by this chamber; this concurrently reduces the right chamber stroke volume and flow relative to the left side. For left atrial pressures (LAP) between 0 and 15 mmHg, CO increased from approximately 3 to > 9 L/min (Starling-like behavior). This was attainable with bronchial flow settings between 0.2 to 0.7 L/min, satisfying physiologic needs. Left atrial pressure and RAP (right atrial pressure) tracked each other. The mean difference, LAP-RAP, remained within 5 mmHg at low filling pressures and approached 0 mmHg difference at high filling pressures. The results showed that the atrial hydraulic shunt method can adequately compensate for and manage physiologic left-right flow differences.

Animals↗
PubMedDate not supplied

A compact and noise free electrohydraulic total artificial heart.

The ABIOMED total artificial heart (TAH) is designed for long-term tether-free use in patients with end-stage heart disease. Blood pumping is achieved through hydraulic fluid motion across flexing diaphragms. The hydraulic power is derived from a miniature centrifugal pump (50% efficiency). Flow directional change needed for alternate left and right filling and ejection is achieved with a rotary valve. With no mechanical contact with the flexing membrane, the wedge angle between the two pumps sandwiching the energy convertor can be easily optimized for anatomic fit. The blood pumps (80 ml strokes) are fitted with trileaflet polyetherurethane valves (24 mm). The TAH is implanted using twist-lock stepless quick connectors to the inflow cuffs and outflow grafts. Left-right flow balance is achieved with an atrial hydraulic shunt placed between the left cuff and inflow valve. Animal studies show that the TAH fits very well in Long Horn calves weighing 90 to 100 kg and can provide cardiac output in excess of 10 L/min. A cadaver (85 kg) study showed the TAH fits within the pericardial region.

Adult↗
PubMedDate not supplied

Progress in the development of a transcutaneously powered axial flow blood pump ventricular assist system.

Development of the Jarvik 2000 intraventricular assist system for long-term support is ongoing. The system integrates the Jarvik 2000 axial flow blood pump with a microprocessor based automatic motor controller to provide response to physiologic demands. Nine devices have been evaluated in vivo (six completed, three ongoing) with durations in excess of 26 weeks. Instrumented experiments include implanted transit-time ultrasonic flow probes and dual micromanometer LV/AoP catheters. Treadmill exercise and heart pacing studies are performed to evaluate control system response to increased heart rates. Pharmacologically induced cardiac dysfunction studies are performed in awake and anesthetized calves to demonstrate control response to simulated heart failure conditions. No deleterious effects or events were encountered during any physiologic studies. No hematologic, renal, hepatic, or pulmonary complications have been encountered in any study. Plasma free hemoglobin levels of 7.0 +/- 5.1 mg/dl demonstrate no device related hemolysis throughout the duration of all studies. Pathologic analysis at explant showed no evidence of thromboembolic events. All pump surfaces were free of thrombus except for a minimal ring of fibrin, (approximately 1 mm) on the inflow bearing. Future developments for permanent implantation will include implanted physiologic control systems, implanted batteries, and transcutaneous energy and data transmission systems.

Animals↗