Biomedical subjects

B P Griffith

Publications and source records attributed to B P Griffith.

At least 451 records · Page 25Linked to original sources

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Lymphangioleiomyomatosis: recurrence after lung transplantation.

Pulmonary lymphangioleiomyomatosis is a disease principally affecting women during child-bearing years that eventually leads to respiratory failure. Recently, it has been listed as an indication for lung transplantation. To date, no cases of recurrent lymphangioleiomyomatosis after lung transplantation have been reported, unlike the experience with sarcoidosis and giant cell interstitial pneumonia. At the University of Pittsburgh Medical Center, four patients have undergone single-lung transplantation for lymphangioleiomyomatosis. We now report that one of these cases developed recurrent lymphangioleiomyomatosis in the allograft lung.

Female↗

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Exercise, education, and quality of life in lung transplant candidates.

In addition to improved functional ability, patients who complete rehabilitation programs typically have positive psychologic changes, including increased motivation and an enhanced quality of life. Potentially, patients with end-stage lung disease awaiting a lung transplant can have similar benefits. However, no studies were identified that examined the impact of an exercise program on quality of life in patients awaiting lung transplantation. This pilot study was an initial step toward evaluating outcomes of a health maintenance program on exercise tolerance and quality of life. Subjects were nine lung transplant candidates who met lung transplant listing criteria and who were randomized to participate in a 6-week health maintenance program consisting of education alone or education plus exercise. Subjects completed cardiopulmonary exercise testing, a 6-minute walk, and the Quality of Well-being scale, Quality of Life Index, and Symptom Frequency/Symptom Distress scale before and after completion of the program. No significant between-group changes were seen. Quality of Well-being scores (p < 0.005) and 6-minute walk distance (p < 0.03) improved over time in both groups. Findings suggest that patients awaiting lung transplantation perceived improved quality of well-being and increased walk distance after participation in a health maintenance program. Education plus exercise conferred no benefits beyond those achieved by education alone. However, the number of subjects studied was small and duration of follow-up was limited.

Activities of Daily Living↗

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Deleterious effects of cardiopulmonary bypass on early graft function after single lung allotransplantation: evaluation of a heparin-coated bypass circuit.

Clinical lung transplantation may necessitate the use of cardiopulmonary bypass during the procedure, resulting in increased morbidity with more severe early graft dysfunction and increased blood loss. A heparin surface-coated cardiopulmonary bypass circuit is now available with improved biocompatibility and reduced systemic heparin requirements and may offer advantages compared with standard uncoated cardiopulmonary bypass circuits. This study investigates in a canine model of single-lung allotransplantation whether cardiopulmonary bypass adversely affects early graft function and whether a heparin-coated cardiopulmonary bypass circuit with reduced systemic heparin dosage improves results compared with standard uncoated cardiopulmonary bypass systems. Fifteen dogs underwent left single-lung allotransplantation with occlusion of the contralateral pulmonary artery and bronchus 1 hour after reperfusion. In one group, five animals underwent the procedure without cardiopulmonary bypass. In the group with uncoated circuits, five animals underwent the procedure with the use of standard uncoated cardiopulmonary bypass circuits with full systemic heparin dosage. In the group with heparin-coated circuits, five animals underwent the procedure with the use of heparin-coated cardiopulmonary bypass circuits and reduced systemic heparin dosage. Early graft function was evaluated by arterial oxygenation, pulmonary mechanics, lung water measurements, and histologic analysis. Hemodynamics and postoperative blood loss were also measured. Two hours after reperfusion, partial pressure of oxygen in arterial blood on an inspired oxygen fraction = 1.0 was significantly greater (p < 0.001) in the group without cardiopulmonary bypass (467 +/- 58 mm Hg) than in the group with uncoated circuits (114 +/- 90 mm Hg) and the group with heparin-coated circuits (193 +/- 105 mm Hg), with no significant difference between the groups undergoing bypass procedures. Lung compliance decreased and lung water increased in all transplanted lungs without significant differences between groups. Histologic analysis did not differentiate between the groups. After reperfusion, cardiac index and mean arterial pressure were significantly reduced in the groups with uncoated circuits and with heparin-coated circuits compared with the group that did not undergo cardiopulmonary bypass (p < 0.001). Postoperative blood loss was significantly less (p < 0.002) in the group that did not undergo cardiopulmonary bypass (90 ml +/- 38 ml) compared with both the group with uncoated circuits (750 +/- 15 ml) and the group with heparin-coated circuits (690 +/- 387 ml), with no significant difference between the groups that underwent bypass. The use of cardiopulmonary bypass with systemic heparinization is detrimental to early graft function in this canine model of left single-lung allotransplantation.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine↗

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A clinical trial comparing University of Wisconsin solution and cold cardioplegic solution with load-independent mechanical parameters.

To evaluate the efficacy of University of Wisconsin solution for clinical heart transplantation, load-independent parameters were used to assess left ventricular function after transplantation. Donor hearts were arrested with and stored in buffered cold cardioplegic solution for control (n = 5) and University of Wisconsin solution for the experimental group (n = 5). Orthotopic transplantations were performed in a routine manner. Mean donor age (cardioplegic solution, 28 +/- 5.2 years; University of Wisconsin solution, 28 +/- 5.1 years) and ischemic times (cardioplegic solution, 181 +/- 27 minutes; University of Wisconsin solution, 224 +/- 23 minutes) were similar. Two hours after reperfusion of the heart, transesophageal echocardiography was used to image the left ventricle at the mid-papillary muscle level, and a high-fidelity catheter-tipped manometer was placed in the left ventricle to record left ventricular pressure simultaneously. These images were digitized during apneic baseline conditions and during an acute reduction in preload from inferior vena caval occlusion. The left ventricular cross-sectional areas were measured and matched with left ventricular pressure from the catheter-tipped manometer to reveal pressure-area relationships. The baseline parameters fractional area change and stroke force were calculated. End-systolic elastance, the slope of end-systolic pressure-area relationship and preload recruitable stroke force, the slope of stroke force versus end-diastolic area were calculated from the inferior vena cava occlusion measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗

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In vivo evaluation of the Nimbus axial flow ventricular assist system. Criteria and methods.

Continuing in vivo trials are being conducted at the University of Pittsburgh using the Nimbus axial flow blood pump (AxiPump). To date, 14 sheep experiments have been performed to address several issues related to short-term support. Six acute experiments (< 6 hr) have been performed to assess hemodynamics related to speed regulation and to determine anatomic placement of the pump and cannulae. Eight short-term survival studies lasting up to 6 days have been performed to evaluate biocompatibility and system reliability, and to establish clinical management protocols. The AxiPump has been used as a left ventricular assist device (LVAD), right ventricular assist device (RVAD), and biventricular assist device (BiVAD) with left ventricular and right atrial cannulation. The AxiPump has demonstrated the ability to assume complete support of either the pulmonary or systemic circulation, or both. We have determined that sufficient surgical access may be obtained through left lateral thoracotomy for both LVAD and RVAD insertion. In the absence of post operative anticoagulation therapy, we have detected subclinical renal cortical infarctions in 6 of 8 short-term animals. Thrombus deposition has been observed at the ventricular cannula tip in 4 of 8 cases--necessitating design changes. Two short-term experiments have been terminated because of bleeding--one due to inflow cannula obstruction and one due to cannula failure. Plasma free hemoglobin levels were all below 15 mg/dl, except for one case complicated by inflow obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

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Pediatric lung transplantation: expanding indications, 1985 to 1993.

The application of lung transplantation to the pediatric population was a natural extension of the success realized in our adult transplant program, which began in 1982. Thirty-two pediatric patients (age range 1 to 18 years) have undergone heart-lung (n = 16), double-lung (n = 14), and single-lung (n = 2) transplantation procedures. The cause of end-stage lung disease was primary pulmonary hypertension (n = 7), congenital heart disease (n = 7), cystic fibrosis (n = 9), pulmonary arteriovenous malformation (n = 2), desquamative interstitial pneumonitis (n = 2), graft-versus-host disease (n = 1), emphysema (n = 1), rheumatoid lung (n = 1), cardiomyopathy (n = 1), and Proteus syndrome (n = 1). Six patients (19%) underwent pretransplantation thoracic surgical procedures. The survival rate was 78% at a mean follow-up of 1.8 years. The survival rate in the 23 recipients without cystic fibrosis was 87% (95% since 1985). The actuarial 1-year survival rate in the nine recipients with cystic fibrosis was 55%. Immunosuppression was cyclosporine (n = 9) or FK 506 (n = 23)-based therapy with azathioprine and steroids. Children were followed up by spirometry, transbronchial biopsy, and primed lymphocyte testing of bronchoalveolar lavage fluid. The mean number of treated episodes of rejection per patient in the groups treated with cyclosporine and FK 506, respectively, was 1.0 and 1.2 at 30 days, 0.67 and 0.38 at 30 to 90 days, and 2.33 and 0.46 at greater than 90 days (p < 0.001, Fisher exact test).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

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Life quality in the era of bridging to cardiac transplantation. Bridge patients in an outpatient setting.

This study provides an empirical evaluation of quality of life in the first two heart transplant candidates with mechanical circulatory support who were transferred (with support in place) to an outpatient setting to await transplantation. Their life quality in physical, emotional, and social domains following transfer was compared to: 1) their previous life quality while hospitalized, 2) life quality among a case series of five other candidates awaiting transplantation during the same time period, and 3) life quality among recent samples of heart recipients from our center and elsewhere. The transferred patients improved markedly in physical and emotional well being, with smaller gains in social functioning after leaving the hospital. They not only improved over their own earlier status while hospitalized, but showed life quality advantages over other hospitalized transplant candidates. Overall, they came to more closely resemble transplant recipients, rather than candidates, of similar age and indication for transplant. Outpatient care for selected mechanically supported heart transplant candidates provides an important potential option for the increasing numbers of patients requiring such support for extended time periods. The study yields critical data as fully implantable mechanical circulatory support devices for permanent heart replacement become a possibility.

Adolescent↗

PubMedDate not supplied

Mechanisms of red blood cell trauma in assisted circulation. Rheologic similarities of red blood cell transformations due to natural aging and mechanical stress.

Clinical experience with circulatory support devices has typically shown alteration of patient blood rheology exhibited through increasing blood viscosity and decreasing erythrocyte deformability. Our hemorheologic studies have additionally shown a remarkable increase in red blood cell (RBC) aggregation in the blood of artificial heart patients as compared to healthy donors. These hemorheologic changes may be caused by mechanical trauma to RBCs. The authors hypothesize that the mechanical trauma process, from a rheologic point of view, could be analogous to an "accelerated" RBC aging process. The hypothesis was examined through in vivo and in vitro experiments on RBCs, age-separated on the basis of density, specifically to identify the rheologic similarities between aged and mechanically traumatized RBCs. Older RBCs demonstrated an increased mechanical fragility, a decreased deformability, and a increased ability to aggregate as compared to younger RBCs. RBCs exposed to mechanical stress demonstrated similar alterations in the same rheologic parameters. Our experiments have also shown that mechanical stress decreases the negative surface charge of RBCs as is known to occur in aged RBCs. Similarities found between the processes of RBC mechanical trauma and senescence enhance our understanding of mechanisms of subhemolytic trauma incurred in assisted circulation. This may improve the design and evaluation of future heart assist devices through minimizing shear induced blood trauma.

Animals↗

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Occult restrictive hemodynamics after pediatric heart transplantation.

BACKGROUND: Although resting hemodynamics after pediatric heart transplantation are generally within normal limits, we hypothesized that occult restrictive hemodynamics suggesting diastolic dysfunction may be unmasked by acute volume loading (fluid challenge) during cardiac catheterization. We wished to determine the incidence of diastolic dysfunction and to assess whether it progressed over time. METHODS: From 1988 through 1993, a total of 100 fluid challenges were performed at the time of surveillance endomyocardial biopsy in 31 survivors of orthotopic heart transplantation. Cyclosporine-based immunosuppression was used in 16 patients, and FK506 was used in 15 patients. Right heart hemodynamics and cardiac output (thermodilution) were obtained at baseline and after a fluid challenge with 10 ml/kg of normal saline solution. The data were analyzed to determine whether type of immunosuppression or time elapsed since transplantation predicted the response to fluid challenge. RESULTS: Baseline hemodynamics were normal; however, a marked increase in atrial filling pressures occurred after fluid challenge (p < 0.001). Findings were similar in cyclosporine- and FK506-treated patients. Hemodynamic response to fluid challenge was not related to duration of time since transplantation, including studies on patients surviving more than 4 years. CONCLUSIONS: Diastolic dysfunction after heart transplantation is common; however, the abnormalities do not progress in severity, suggesting stable long-term graft function.

Adolescent↗

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The effect of supplemental beta-carotene on immunologic indices in patients with AIDS: a pilot study.

Patients with the acquired immunodeficiency syndrome (AIDS) are characterized by a decrease in the number of T helper cells, a defect that is linked to the impaired immunologic competence. Vitamin A and its dietary precursor, beta-carotene, increase absolute T helper cell counts as well as indices of T cell function in both human and animal models. To determine if short-term beta-carotene treatment affects T lymphocyte subsets in patients with AIDS, a single-blind, non-randomized clinical trial of beta-carotene was performed in seven patients with AIDS. Enrollment criteria included no evidence of: a) active opportunistic infection: b) greater than 1 kilogram change in weight in the month preceding enrollment; c) chronic diarrhea or malabsorption; and d) hepatic disease or significant anemia. Beta-carotene was given with meals in two divided doses of 60 mg/day for four weeks; this was followed by no therapy for six weeks. Samples for total white blood cell, lymphocyte and T lymphocyte subset counts were measured at baseline, at the end of four weeks of treatment and another six weeks after treatment had stopped. P24 antigen, beta-2 microglobulin and liver function tests were also measured. All subjects tolerated the treatment well without evidence of toxicity. In response to beta-carotene, total lymphocyte counts rose by 66 percent (.05 < p < .10), and CD4+ cells rose slightly, but insignificantly, in the entire group. In all three of the patients who had baseline CD4+ cells greater than 10/microliters, however, the mean absolute increase in CD4+ cells in response to beta-carotene was 53 +/- 10 cells/microliters (p < .01). Six weeks off beta-carotene treatment, the absolute CD4+ cell count returned to pretreatment levels (p < .01). No change was observed in CD8+ cells. P24 antigen and beta-2 microglobulin did not change during treatment. These preliminary observations suggest that short-term treatment with beta-carotene may increase CD4+ cell counts in patients with AIDS who have greater than 10 cells/microliters.

Acquired Immunodeficiency Syndrome↗

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In vivo evaluation of an extracorporeal pediatric centrifugal blood pump.

This paper summarizes the authors' in vivo experience in evaluating a miniature centrifugal blood pump designed for pediatric/neonatal ventricular support. Left ventricular bypass was accomplished in two adult sheep and five juvenile lambs (5.5-80.0 kg) via either central (left ventricle to carotid artery) or peripheral (jugular vein to carotid artery) cannulation. Animals were weaned from mechanical ventilation and continuously monitored. Hemodynamic parameters remained within a normal range over the duration of the bypass. Two of five lambs were electively killed at 8, and 76 hours; the remaining three lambs died from respiratory complications at 33, 44, and 156 hours. There were no mechanical complications, and blood seal integrity was confirmed beyond 6 days. The pump speed was maintained at 3,000-4,500 rpm with pump flow rates between 0.4-1.5 L/min. Average plasma free hemoglobin was below 20 mg/dl in the five lamb experiments. Renal, hepatic, and hematologic indices also remained within physiologic ranges. Histopathologic analyses of major organs revealed renal cortical infarctions in two of five lambs. Examination of the pump surfaces after explant indicated small areas of thrombus in the housing adjacent to the outflow ports in two experiments. These encouraging results support further testing and refinement of this miniature centrifugal pump.

Animals↗

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Survival for up to six months in calves supported with an implantable axial flow ventricular assist device.

This paper summarizes the authors' in vivo experience to date with an implantable axial flow blood pump designed for long-term ventricular support. This small, valveless pump with blood-lubricated bearings has been implanted in six calves (83 +/- 6 kg) as a left ventricular assist device (LVAS). The left ventricle and descending thoracic aorta were cannulated by left thoracotomy, and the pump was placed in a subcutaneous pocket below the costal margin. Animals remained hemodynamically stable throughout the course of support during partial left ventricular bypass. Five animals were killed after 15, 27, 52, 57, and 181 days. The longest survivor (181 days) demonstrated normal pump function at the time death. Pump speed was maintained at 10,100 +/- 100 rpm, with an average pump flow rate of 4.9 +/- 0.5 L/min under resting physiologic conditions. Average plasma free hemoglobin was 17.4 +/- 7.5 mg/dl. Renal, hepatic, and hematologic indices remained within physiologic range in all of these animals, except during the immediate postoperative period. Histopathologic analyses of major organs after death revealed small renal cortical infarcts in five of six animals; the remaining organs were normal. These animal studies support the feasibility of this small implanted axial flow pump for long-term ventricular assistance.

Animals↗

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Continued development of the Nimbus/University of Pittsburgh (UOP) axial flow left ventricular assist system.

Nimbus and the University of Pittsburgh (UOP) have continued the development of a totally implanted axial flow blood pump under the National Institutes of Health (NIH) Innovative Ventricular Assist System (IVAS) program. This 62 cc device has an overall length of 84 mm and an outer diameter of 34.5 mm. The inner diameter of the blood pump is 12 mm. It is being designed to be a totally implanted permanent device. A key achievement during the past year was the completion of the Model 2 pump design. Ten of these pumps have been fabricated and are being used to conduct in vitro and in vivo experiments to evaluate the performance of different materials and hydraulic components. Efforts for optimizing the closed loop speed control have continued using mathematical modeling, computer simulations, and in vitro and in vivo testing. New hydraulic blade designs have been tested using computational fluid dynamics (CFD) and flow visualization. A second generation motor was designed with improved efficiency. To support the new motor, a new motor controller fabricated as a surface mount PC board has been completed. The program is now operating under a formal QA system.

Animals↗

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The cool seal system: a practical solution to the shaft seal problem and heat related complications with implantable rotary blood pumps.

A critical issue facing the development of an implantable, rotary blood pump is the maintenance of an effective seal at the rotating shaft. Mechanical seals are the most versatile type of seal in wide industrial applications. However, in a rotary blood pump, typical seal life is much shorter than required for chronic support. Seal failure is related to adhesion and aggregation of heat denatured blood proteins that diffuse into the lubricating film between seal faces. Among the blood proteins, fibrinogen plays an important role due to its strong propensity for adhesion and low transition temperature (approximately 50 degrees C). Once exposed to temperature exceeding 50 degrees C, fibrinogen molecules fuse together by multi-attachment between heat denatured D-domains. This quasi-polymerized fibrin increases the frictional heat, which proliferates the process into seal failure. If the temperature of the seal faces is maintained well below 50 degrees C, a mechanical seal would not fail in blood. Based on this "Cool-Seal" concept, we developed a miniature mechanical seal made of highly thermally conductive material (SiC), combined with a recirculating purge system. A large supply of purge fluid is recirculated behind the seal face to augment convective heat transfer to maintain the seal temperature below 40 degrees C. It also cools all heat generating pump parts (motor coil, bearing, seal). The purge consumption has been optimized to virtually nil (< 0.5 cc/day). An ultrafiltration unit integrated in the recirculating purge system continuously purifies and sterilizes the purge fluid for more than 5 months without filter change. The seal system has now been incorporated into our intraventricular axial flow blood pump (IVAP) and newly designed centrifugal pump. Ongoing in vivo evaluation of these systems has demonstrated good seal integrity for more than 160 days. The Cool-Seal system can be applied to any type of rotary blood pump (axial, diagonal, centrifugal, etc.) and offers a practical solution to the shaft seal problem and heat related complications, which currently limit the use of implantable rotary blood pumps.

Animals↗

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Plasma protective effect on red blood cells exposed to mechanical stress.

Hemodilution with plasma expanders is a widely applied practice during extracorporeal circulation and hemodialysis. Despite the immediate beneficial effects of hemodilution, such as reduction of blood viscosity and red blood cell (RBC) aggregation, elevation of blood flow in the microcirculation, etc., the dilution of plasma may cause some unfavorable effects on RBCs, amplifying the mechanical damage caused by circulatory assist devices. The authors investigated the effect of partial and total replacement of plasma on susceptibility of human and bovine RBCs to mechanical stress in vitro. Hemolysis was measured after the exposure of RBCs suspended in different media to similar mechanical stress. Experiments were performed at room temperature with control of osmolality and viscosity of the suspension media. The lowest hemolysis was obtained for RBCs suspended in serum, plasma, and albumin solutions. Hemolysis in PBS and Dextran suspensions was more than three times higher than that in plasma (p < 0.001). The protective effect depended upon protein concentration. Human RBCs were found to be significantly more sensitive to mechanical stress than bovine RBCs in all investigated suspension media (p < 0.005). Human RBCs from men suspended in plasma were found to be significantly (p < 0.05) more fragile than RBCs from women. The presence of even small amounts of plasma (such as 25%) in the suspension media significantly (p < 0.001) decreased hemolysis. However, a 30% replacement of plasma with PBS or Dextran solutions caused a statistically significant (p < 0.001) increase in mechanical hemolysis. This suggests that a decrease in the concentration of plasma proteins due to hemodilution may elevate blood damage during extracorporeal circulation and hemodialysis.

Animals↗

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An implantable centrifugal blood pump for long term circulatory support.

A compact centrifugal blood pump was developed as an implantable left ventricular assist system. The impeller diameter is 40 mm and the pump dimensions are 55 x 64 mm. This first prototype was fabricated from titanium alloy, resulting in a pump weight of 400 g including a brushless DC motor. Weight of the second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon to improve blood compatibility. Flow rates of over 7 L/min against 100 mmHg 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 as a shaft seal. In this seal system, 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. The purge fluid is continuously purified and sterilized by an ultrafiltration filter incorporated into 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 apex-descending aorta bypass was performed utilizing a PTFE (Polytetrafluoroethylene) vascular graft, with the pump placed in the left thoracic cavity. In two in vivo experiments, pump flow rate was maintained at 5-8 L/min, and pump power consumption remained stable at 9-10 W. All plasma free hemoglobin levels were measured at < 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (< 0.5 ml/ day). Both animals remain under observation after 162 and 91 days of continuous pump function.

Animals↗

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Long-term animal experiments with an intraventricular axial flow blood pump.

A miniature intraventricular axial flow blood pump (IVAP) is undergoing in vivo evaluation in calves. The IVAP system consists of a miniature (phi 13.9 mm) axial flow pump that resides within the left ventricular (LV) chamber and a brushless DC motor. The pump is fabricated from titanium alloy, and the pump weight is 170 g. It produces a flow rate of over 5 L/min against 100 mmHg pressure at 9,000 rpm with an 8 W total power consumption. The maximum total efficiency exceeds 17%. A purged lip seal system is used in prototype no. 8, and a newly developed "Cool-Seal" (a low temperature mechanical seal) is used in prototype no. 9. In the Cool-Seal system, a large amount of purge flow is introduced behind the seal faces to augment convective heat transfer, keeping the seal face temperature at a low level for prevention of heat denaturation of blood proteins. The Cool-Seal system consumes < 10 cc purge fluid per day and has greatly extended seal life. The pumps were implanted in three calves (26, 30, and 168 days of support). The pump was inserted through a left thoracotomy at the fifth intercostal space. Two pursestring sutures were placed on the LV apex, and the apex was cored with a myocardial punch. The pump was inserted into the LV with the outlet cannula smoothly passing through the aortic valve without any difficulty. Only 5 min elapsed between the time of chest opening and initiation of pumping. Pump function remained stable throughout in all experiments. No cardiac arrhythmias were detected, even at treadmill exercise tests. The plasma free hemoglobin level remained in the acceptable range. Post mortem examination did not reveal any interference between the pump and the mitral apparatus. No major thromboembolism was detected in the vital organs in Cases 1 or 2, but a few small renal infarcts were detected in Case 3.

Animals↗

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Assessment of timing right ventricular assist device withdrawal using left ventricular assist device filling characteristics.

Right ventricular assist devices (RVAD) are often needed on a short term basis in patients who develop RV failure after left ventricular assist device (LVAD) implantation. The purpose of this study was to use LVAD filling characteristics to help determine the timing for weaning a patient from RVAD support. Eleven patients (age 50 years +/- 15) supported with an LVAD (Novacor) and an RVAD (Biomedicus or ABIOMED) were studied. Eight patients (RV recovery group) were studied before RVAD removal and all were successfully weaned from RVAD support. Five patients (RV failure group) were studied at the time of RVAD placement to determine baseline characteristics of RV failure. Simultaneous measures of LVAD volume and routine hemodynamics were recorded during periods of high and low RVAD flow. The LVAD filling was assessed as the first derivative of LVAD volume and the mean filling rate for each cardiac cycle was calculated and averaged over 10 sec periods at both RVAD flows. The mean pump rate corrected filling rates did not change in the RV recovery group (89 +/- 13 vs. 87 +/- 8 ml/beat) and significantly decreased in the RV failure group (84 +/- 19 vs. 62 +/- 22 ml/ beat) (p < 0.001) with decreasing RVAD flow. These data suggest that LVAD filling rates may be used to assess RV systolic function and the proper timing of RVAD removal in selected patients.

Adult↗