Biomedical subjects

Kimberly Robertson

Publications and source records attributed to Kimberly Robertson.

7 recordsLinked to original sources

PubMed2005

Direct thrombolytic therapy for intraventricular thrombosis in patients with the Jarvik 2000 left ventricular assist device.

One of the complications that can occur with continuous, axial-flow left ventricular assist devices (LVADs) is thrombosis within the left ventricle, adjacent to the device's inflow conduit, which may cause inflow obstruction and recurrent heart failure. We describe 2 cases in which we used a catheter to continuously infuse recombinant tissue plasminogen activator (tPA) into the left ventricle until signs of successful thrombolysis was achieved. By monitoring the result and administering only as much tPA as necessary to achieve thrombolysis, we were able to successfully lyse the obstructing thrombus with a minimal dose of tPA without causing any significant bleeding problems. This technique may be useful for managing this potentially serious complication while minimizing the risk of treatment.

Cardiac Catheterization↗

PubMed2005

Antiphospholipid syndrome with anti-prothrombin autoantibodies in a patient with an axial-flow left ventricular assist device.

Autoantibodies to prothrombin, first described almost 50 years ago, are paradoxically associated with thrombosis. Described is an unusual case of fatal hypercoagulability in a patient with multiple arterial and venous thromboembolic complications despite intense anticoagulation while being bridged to transplantation with a left ventricular assist device. Serum analysis revealed the presence of prothrombin autoantibodies and high titers of anti-nuclear antibodies, and autopsy revealed pulmonary arteriolar vasculitis. These findings suggest an autoimmune basis for the presence of anti-prothrombin antibodies and the hypercoagulable state observed in the present case.

Antibodies, Antiphospholipid↗

PubMed2004

Relationship between anorexia and loss of serotonin uptake sites in brain of mice and rats receiving d-norfenfluramine or d-fenfluramine.

Previously, we have shown that repeated administration of d-fenfluramine (D-F) to rats is associated with development of tolerance to the initial anorexia, but that in mice no such tolerance seems to occur. In the first study, we show that chronic administration of neither d-norfenfluramine (D-NF; the principal metabolite of D-F) nor the serotonin (5-HT) 2C receptor agonist m-chlorophenyl-piperazine (mCPP) is associated with the development of anorectic tolerance tested using a dessert protocol. However, compared with mice receiving these drugs for the first time, both of these chronic treatments were associated with a significant attenuation of Fos immunoreactivity (Fos-ir) in several brain regions, including bed nucleus of the stria terminalis, paraventricular hypothalamus, and central nucleus of amygdala. This attenuation is similar to that described previously in rats. Because loss of efficacy of these agents could be related to loss of 5-HT transporter (5-HTT) sites, their presumptive primary mode of action, in the final study we determined the effect of various, low-dose regimens of D-F and D-NF on 5-HT uptake in frontal cortex of mice and rats. We show in mice that D-F causes a greater loss of 5-HT uptake than D-NF, and that at the lowest dose regimen used uptake was unaffected in rats but was reduced in mice. The data are discussed in terms of the species difference in behavioral tolerance and differences in neurochemical profile of D-F and D-NF.

Animals↗

PubMed2003

Continuous flow pumps and total artificial hearts: management issues.

Feasibility studies are underway for new axial flow ventricular assist systems and with a total artificial heart (TAH). The axial flow pumps provide continuous flow from the left ventricle (LV) to the aorta; the TAH provides pulsatile flow to the pulmonary and systemic circulation. Understanding the differences between these systems is necessary for appropriate patient selection and management. We compared the Jarvik 2000 axial-flow pump and the AbioCor TAH. The Jarvik 2000 pump is placed in the LV with its outflow graft anastomosed to the aorta. This system is used for bridge-to-transplantation and destination therapy. The AbioCor TAH provides complete circulatory support. The AbioCor is used for destination therapy in patients expected to die in less than 30 days. Worldwide, 45 patients have received the Jarvik 2000 as a bridge to transplantation (n = 34) or destination therapy (n = 11) for an average duration of support of 132.8 days (5 to 853 days). In 30 bridge-to-transplantation cases, 14 patients (47%) have undergone heart transplantation, 5 (17%) continue to be supported with the Jarvik 2000 device, and 11 (37%) have died. Five of 7 patients supported by the AbioCor TAH survived beyond the perioperative period; 4 were ambulatory, 2 were discharged from the hospital, and 1 is at home 13 months after implantation. Anticoagulation therapy and infection management are necessary for both systems. Therapy with inotropic agents, vasoactive drugs, a pacemaker, and electrolyte normalization is necessary for Jarvik patients. AbioCor-supported patients do not require medications to support heart function. Vasoactive agents may be useful for controlling blood pressure.

Heart Failure↗

PubMed2003

Continuous axial-flow left ventricular assist device (Jarvik 2000) maintains kidney and liver perfusion for up to 6 months.

BACKGROUND: The Jarvik 2000 axial flow left ventricular assist device (LVAD), under development for the past decade, has the potential to support patients temporarily until cardiac transplantation or as a permanent circulatory support, without the size limitations of other implantable systems. METHODS: To assess its ability to perfuse the kidneys and liver, we monitored renal and hepatic function in 10 patients who received the Jarvik 2000 LVAD as a bridge to transplantation. Left ventricular assistance was maintained for up to 214 days (> 6 months), and renal and hepatic function were monitored at least weekly. RESULTS: Renal function before LVAD implantation in these patients was normal in 7 (creatinine, < 1.5) and moderately impaired in 3 (creatinine, 1.2 to 2.0). Hepatic function was normal in 7 patients before LVAD implantation (total bilirubin< 1.2; serum glutamic-oxaloacetic transaminase (SGOT), < 40; serum glutamic-pyruvic transaminase (SGPT), < 50) and normal at the time of transplantation in all 10 patients. Of the 3 patients with abnormal hepatic function before LVAD implantation, 1 patient had also had moderate renal dysfunction. CONCLUSIONS: Despite reduced pulsatility, the Jarvik 2000 LVAD improves or maintains excellent renal and hepatic function during periods of circulatory assistance in patients awaiting transplantation.

Adult↗

PubMed2003

Effect of repeated administration of dexfenfluramine on feeding and brain Fos in mice.

The present study examines whether repeated administration of dexfenfluramine (DFEN) to mice is associated with progressive attenuation of its anorectic action and induction of Fos-immunoreactivity (Fos-ir) in some brain regions, both known effects in rats. ICR:Cd-1 mice were adapted to receiving for 30 min daily a sweetened milk gelatin dessert in addition to ad libitum access to chow. Mice were then injected with either DFEN (5-10 mg/kg) or saline vehicle every other day. These doses of DFEN acutely suppressed intake by approximately 50% and this action was sustained for at least eight injections. The anorectic effect of DFEN was no different between drug-naïve and DFEN-pretreated mice under conditions that produce complete tolerance in rats. In addition, unlike in rats, the acute anorectic effect of m-chlorophenylpiperazine (mCPP) was unaffected by prior DFEN treatment. Mice were perfused after the intake test on the final experimental day and their brain processed for Fos-ir. DFEN induced Fos-ir in brain regions analogous to those reported in rats and, also, as in rats, DFEN pretreatments reduced substantially the Fos-ir induced by acute DFEN in regions including central nucleus of amygdala, bed nucleus of stria terminalis, and the paraventricular hypothalamus (magno- and parvocellular divisions; PVN). Thus, while DFEN pretreatments reduce the effects of DFEN in many brain regions in both rats and mice, mice are unlike rats insofar as there is no tolerance to the anorectic action, at least in the nondeprivation protocol used here.

Animals↗

PubMedDate not supplied

Quality of life in bridge-to-transplant patients with chronic heart failure after implantation of an axial flow ventricular assist device.

Research suggests that ventricular assist devices improve quality of life for congestive heart failure patients awaiting heart transplantation. Axial flow ventricular assist devices like the Jarvik 2000 (Jarvik Heart, Inc., New York, NY) represent the newest type of ventricular assist device technology, but their effects on quality of life are not well understood. Therefore, the authors administered the Minnesota Living with Heart Failure Questionnaire to patients who had the Jarvik 2000 implanted as a bridge to heart transplantation. Patients completed the Minnesota Living with Heart Failure Questionnaire immediately before device implantation, 1 month after implantation, immediately before heart transplantation, and 1 month after transplantation. One month after implantation of the device, the nine patients who completed the study showed significant improvements in physical (p<0.008), emotional (p<0.02), and overall (p<0.008) quality of life. These improvements were maintained until the device was explanted. The authors conclude that implantation of the Jarvik 2000 ventricular assist device can substantially improve quality of life for patients awaiting heart transplantation.

Adult↗