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PubMed2001

Hydrosolidarity intergenerational challenges: long-term commitment for long-term issues.

The year 2000 Young Professionals Seminar focused on long-term intergenerational challenges. Water related problems are symptoms of complex and ultimately societal problems linked to human behaviour, political support and managerial and institutional structures. Although integrated water resources management is presented as a solution, it is not always well understood, and can create a sense of hopelessness among professionals. To make it operational requires long-term commitments among various professionals and the involvement of new actors. A number of key topics crystallised as needing further attention, including ethical dimensions in policy making, the development of a framework for a "Future Generation Impact Assessment" (FGIA), and efforts to achieve true dialogue among stakeholders. Young water professionals must become more involved in political processes and take active part in institutional changes. Such engagement will require changes in the working environment facing many young professionals that causes frustration due to inefficient and conservative hierarchical structures and the lack of transparency.

Conservation of Natural Resources↗

PubMed2006

Impaired long-term memory and long-term potentiation in N-type Ca2+ channel-deficient mice.

Voltage-dependent N-type Ca(2+) channels, along with the P/Q-type, have a crucial role in controlling the release of neurotransmitters or neuromodulators at presynaptic terminals. However, their role in hippocampus-dependent learning and memory has never been examined. Here, we investigated hippocampus-dependent learning and memory and synaptic plasticity at hippocampal CA3-CA1 synapses in mice deficient for the alpha(1B) subunit of N-type Ca(2+) channels. The mutant mice exhibited impaired learning and memory in the Morris water maze and the social transmission of food preference tasks. In particular, long-term memory was impaired in the mutant mice. Interestingly, among activity-dependent long-lasting synaptic changes, theta burst- or 200-Hz-stimulation-induced long-term potentiation (LTP) was decreased in the mutant, compared with the wild-type mice. This type of LTP is known to require brain-derived neurotrophic factor (BDNF). It was found that both BDNF-induced potentiation of field excitatory postsynaptic potentials and facilitation of the frequency of miniature excitatory postsynaptic currents (mEPSCs) were reduced in the mutant. Taken together, these results demonstrate that N-type Ca(2+) channels are required for hippocampus-dependent learning and memory, and certain forms of LTP.

Analysis of Variance↗

PubMed2001

Laser-assisted uvulopalatoplasty: short-term and long-term results.

OBJECTIVE: Snoring causes many problems for both snorers and family members. Significant improvement has been reported in subjective measures of snoring after laser-assisted uvulopalatoplasty (LAUP). However, there were few studies of the long-term results of LAUP from a large number of patients. The purpose of this study was to compare the short-term versus long-term results in patients undergoing this procedure. METHODS: LAUP has been performed on 340 snorers. The majority of the patients were male with simple snoring by history and confirmed by polysomnographic study. Data on patients were compared from preoperative to the short-term (6 months) and long-term (more than 3 years) postoperative assessment points. Statistic analysis was performed to assess the significance of differences between groups. RESULTS: Significant improvement was observed in snoring scale at 6 months and long-term. The mean follow-up was 40.5 months with a range of 36 to 50 months. There were significant differences between short-term and long-term results (P < 0.05). The change in body mass index was significantly different in the patients with and without recurrence (1.9 vs 0.5 kg/m(2), P < 0.01). Two hundred fifty-five (75%) patients had long-term clinical success, and 34 (12%) patients with short-term success failed long-term. CONCLUSION: LAUP in the treatment of simple snoring results in long-term success. However, patients are at risk of recurrence if they gain weight.

Adult↗

PubMed1990

Different voltage-dependent thresholds for inducing long-term depression and long-term potentiation in slices of rat visual cortex.

In the hippocampus and neocortex, high-frequency (tetanic) stimulation of an afferent pathway leads to long-term potentiation (LTP) of synaptic transmission. In the hippocampus it has recently been shown that long-term depression (LTD) of excitatory transmission can also be induced by certain combinations of synaptic activation. In most hippocampal and all neocortical pathways studied so far, the induction of LTP requires the activation of N-methyl-D-aspartate (NMDA) receptor-gated conductances. Here we report that LTD can occur in neurons of slices of the rat visual cortex and that the same tetanic stimulation can induce either LTP or LTD depending on the level of depolarization of the postsynaptic neuron. By applying intracellular current injections or pharmacological disinhibition to modify the depolarizing response of the postsynaptic neuron to tetanic stimulation, we show that the mechanisms of induction of LTD and LTP are both postsynaptic. LTD is obtained if postsynaptic depolarization exceeds a critical level but remains below a threshold related to NMDA receptor-gated conductances, whereas LTP is induced if this second threshold is reached.

2-Amino-5-phosphonovalerate↗

PubMed1997

Group 1 and 2 metabotropic glutamate receptors play differential roles in hippocampal long-term depression and long-term potentiation in freely moving rats.

This study examined the role of metabotropic glutamate receptors (mGluRs) in hippocampal long-term depression (LTD) in vivo. The group 1 mGluR antagonist (S)4-carboxyphenylglycine (4CPG), group 1/2 antagonist (RS)-alpha-methyl-4-carboxyphenylglycine (MCPG), and group 2 antagonists (RS)-alpha-methylserine-O-phos-phate monophenyl ester (MSOPPE) and (2S)-alpha-ethylglutamic acid (EGLU) were used. The NMDA receptor antagonist D(-)-2-amino-5-phosphonopentanoic acid (AP5) was used to examine the NMDA receptor contribution to the observed LTD. Adult male Wistar rats underwent implantation of stimulating and recording electrodes into the Schaffer collaterals and CA1 stratum radiatum, respectively. After recovery of 5-7 d, the field EPSP was measured from freely moving animals. Drugs were applied either before or after 1 Hz low-frequency train (LFT) or 100 Hz stimulation via a cannula implanted in the lateral cerebral ventricle. Nine hundred pulses at 1 Hz produced an LTD that was marked and long-lasting. This LTD was completely inhibited by pre-LFT application of AP5. MCPG inhibited LTD from 2 hr post-LFT. 4CPG partially impaired LTD. MSOPPE and EGLU completely blocked induction of LTD, although short-term depression remained intact. MSOPPE did not block long-term potentiation (LTP) induced by 100 Hz stimulation, whereas 4CPG produced a significant inhibition. When MSOPPE was present, LTD could not be induced either before or after LTP induction, whereas LTD could be induced in an identical protocol in vehicle-injected animals. These results suggest a differential role for mGluRs in NMDA receptor-dependent hippocampal LTD in vivo. Group 1 mGluRs may play a role in both LTD and LTP, whereas group 2 mGluRs may be critically involved only in LTD induction.

2-Amino-5-phosphonovalerate↗

PubMed2004

The reproducibility and short-term and long-term repeatability of sonographic measurement of splenic length.

This study was undertaken to evaluate the reproducibility (interobserver variability), and the short-term and long-term repeatability (intraobserver variability) of sonographic measurement of the maximum and mean splenic length. Ultrasound (US) measurements of the splenic length were performed in 43 subjects, ages 30 to 59 years old (mean age = 44.5 years). Each subject attended three US sessions: baseline examination and 30 min and 8 weeks after the baseline examination. In each session, US examinations of the spleen were performed and the splenic length was measured by four operators. In each examination, the splenic length was measured 3 times, and the maximum and mean values were obtained. The overall reproducibility of the measurements of maximum and mean splenic lengths were 67% and 89%, respectively. The short-term repeatability in measuring the maximum and mean splenic lengths were 87% and 94%, respectively, whereas the long-term repeatabilities were 61% and 76%, respectively. The reproducibility and short-term and long-term repeatability of the measurement of mean splenic length were higher than those of the maximum splenic length. In the mean and maximum splenic length measurement, the short-term repeatability was higher than the long-term repeatability. The results suggested that the mean splenic length has a higher reliability in sonographic measurement and should be used in routine clinical practice. Measurement errors should be considered when evaluating the changes of splenic length in serial US examinations, particularly in long-term follow-up.

Adult↗

PubMed2003

Short-term, intermediate-term, and long-term mortality in patients hospitalized for stroke.

Cerebrovascular disease is the third leading cause of death and the primary cause of long-term disability in the United States. Although the risk factors for stroke have been well defined, less is known about stroke mortality over varying time periods within the same cohort of patients. The purpose of this study is to define rates of short-term, intermediate-term, and long-term stroke mortality among patients experiencing a first-ever hemorrhagic or ischemic stroke between 1994 and 1998. Patients were identified from the Patient Treatment Files of the Department of Veterans Affairs (VA). We included all patients who were discharged from a VA inpatient facility with a diagnosis of acute stroke. Patients were excluded from the study if they had an admission within the previous 5 years for stroke or hemiplegia. We obtained information on the patient's age, gender, and coexisting illnesses. Unadjusted and adjusted 30-day mortality rates were computed using Kaplan-Meier analyses and Cox proportional hazards regression models. The survival-dependent Cox proportional hazards regression models were run for 31-90 days and 91-365 days from the index admission date, for patients who had survived to the start of each of these time periods. Separate models were run for ischemic (n = 34,866 patients) and hemorrhagic (n = 5,442 patients) strokes. Unadjusted 30-day mortality was 8.2 and 20.5% for ischemic and hemorrhagic strokes, respectively. The adjusted 30-day mortality rate was 7.4 and 18.8% for ischemic and hemorrhagic strokes, respectively. For ischemic stroke, age 65 years and older was associated with an increased risk for short-term, intermediate-term, and long-term mortality, while chronic heart failure was associated with an increased risk for short-term and long-term mortality. For hemorrhagic stroke, age 75 years and older, malignancy, and chronic heart failure were associated with increased mortality during all three time periods. Thirty-day mortality is over two times greater following hemorrhagic stroke vs. ischemic stroke. For patients who survive 30 days after an ischemic stroke, the risk factor that remains significantly associated with long-term mortality, which may be improved with appropriate process of care, is chronic heart failure. For patients with a hemorrhagic stroke, variables that remain significantly associated with increased short-term and long-term mortality include malignant neoplasm and chronic heart failure. Information on stroke mortality is important for patients, physicians, and researchers. In addition to stroke treatment, clinicians must be able to provide families of stroke victims with appropriate prognostic information. Further work is needed to assess the impact of actual care patterns, for the above identified risk factors, on stroke prognosis over varying time periods.

Adult↗

PubMed2005

[Short-term and long-term inpatient psychotherapy -- indications, results, predictors].

OBJECTIVES: This study investigated differences between patients in both short-term and long-term inpatient psychotherapy. Results for both settings as well as predictors of treatment outcomes were determined. METHODS: Consecutive patients of the Giessen University Clinic for Psychosomatics and Psychotherapy, who were treated during a two-year period in both short- and long-term treatment settings, were studied prospectively (N = 166; return-rate 70 %). Standardized questionnaires were applied for distress (SCL-90 R), physical complaints (GBB 24) and interpersonal problems (IIP-D) as well as for object relationships (IPO). RESULTS: In concordance with treatment concepts, patients in short-term psychotherapy had a more acute onset of symptoms, were more highly distressed and better occupationally integrated; patients in long-term treatment suffered more frequently from chronic psychosomatic disorders, personality disorders and comorbid somatic conditions. In both treatment settings distress and physical complaints decreased considerably and remained quite stable during follow-up. Concurring predictors of outcome were more adaptive patterns of object and interpersonal relationships as well as social resources. No differences were seen between the short-term and long-term treatment for utilization of ambulatory psychotherapy after discharge. DISCUSSION: The study shows that a differentiation between short- and long-term treatments, even within one psychosomatic hospital unit, allows for differential indication and treatment concepts.

Adult↗

PubMed1993

Loss of long-term repopulating ability in long-term bone marrow culture.

We have studied the maintenance of stem cells with long-term multilineage repopulating ability from murine bone marrow, cultured on a pre-established bone marrow-derived stromal cell layer, both in a qualitative and quantitative way. Female bone marrow cells were cultured for a period of 1-4 weeks and compared with uncultured cells for their ability to establish and maintain a level of 50% chimerism in a sex-mismatched bone marrow transplantation model. Chimerism was determined in nucleated cells using fluorescence in situ hybridization with a murine Y-chromosome-specific probe. We observed a rapid decline in the ability of cultured marrow cells to repopulate the blood, bone marrow, spleen, and thymus of sublethally irradiated male recipients. After 4 weeks of culture only 5% of the long-term repopulating ability of the inoculated bone marrow cells remained. The remaining long-term repopulating cells, however, had similar qualities to establish and maintain long-term engraftment compared to fresh bone marrow, as judged from their ability to give stable chimerism over a period of 6 months. These observations are relevant for the therapeutic applications of long-term bone marrow cultures in purging protocols prior to autologous bone marrow transplantation of acute and chronic myeloid leukemic patients, and for the use of long-term marrow cultures when introducing foreign genetic material in hematopoietic stem cells.

Animals↗

PubMedDate not supplied

[A possible mechanism of the influence of neuromodulators and modifiable inhibition on long-term potentiation and long-term depression of excitatory inputs to main hippocampal neurons].

A hypothetic mechanism explaining the influence of various neuromodulators and modifiable disynaptic inhibition on the long-term potentiation and depression (LTP and LTD) of excitatory inputs to granule and pyramidal hippocampal cells is proposed. According to this mechanism, facilitation of the LTD/LTP of excitatory inputs to an inhibitory interneuron caused by the action of a neuromodulator on a receptor bound with Gi/0/(Gs or Gq/11) protein can reduce/augment the GABA release, weaken/intensify the target cell inhibition, and promote the induction of the LTP/LTD of excitatory inputs to this cell. In the absence of the inhibition, the same neuromodulator would promote the LTD/LTP induction in the target cell by activating the same receptor types. The resulting effect of a neuromodulator on a target cell depends on the ratio between the "strengths" of its excitatory and inhibitory inputs, on the presence of receptors of the same or different types at the interneuron and the target cell, and on the neuromodulator concentration due to its different affinity for receptors, interaction with which provide its influence on postsynaptic processes in opposite directions. The consequences of suggested mechanism are in agreement with the known experimental data.

Animals↗

PubMed1997

Pediatric polytrauma: short-term and long-term outcomes.

OBJECTIVE: To assess the short-term and long-term outcomes of pediatric polytrauma patients and to analyze the extent to which short-term outcomes can predict long-term outcomes. MATERIALS AND METHODS: All pediatric polytrauma patients (Injury Severity Score of > or = 16, < or = 15 years of age) who were treated at a Level I trauma center between 1985 and 1989 and who were 18 years or older at follow-up (1996) were included. Short-term outcomes were quantified using the Glasgow Outcome Scale. The Functional Independence Measure, the RAND-36, and questions on social outcome were used to assess long-term outcomes. MEASUREMENTS AND MAIN RESULTS: Fifty-nine of 74 patients survived (80%). At 1 year after injury, 22% were disabled, mainly due to severe brain injuries, and 32% had changed school. After 9 years of follow-up, the degree of physical disablement was low (12%). Cognitive impairments were found in 42% of the patients. Only 10% were in receipt of disablement allowances; 76% were employed or attended school. The quality of life enjoyed by the patients (RAND-36) did not differ from that enjoyed by a healthy reference population. The Glasgow Outcome Scale (from 6 weeks onward) was a good predictor of long-term disablement. CONCLUSIONS: Although the short-term impact of injuries is extensive, the long-term outcomes are satisfactory. Severe injuries sustained during childhood do not lead to a diminished quality of life during adulthood.

Adolescent↗

PubMed2002

Survival and quality of life: short-term versus long-term ventilator patients.

OBJECTIVE: Examine postdischarge mortality, quality of life, and charges for care for short-term (>24 and 96 hrs) ventilator patients. DESIGN: Prospective longitudinal descriptive study. SETTING: Posthospital discharge follow-up in homes, nursing homes, and rehabilitation centers. PATIENTS: Intensive care unit patients who required >24 hrs of continuous in-hospital mechanical ventilation were enrolled from February 1997 through March 1999. Patients living to hospital discharge were followed for 1 yr postdischarge. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: A total of 538 patients were studied. In-hospital mortality was 47.4%, with a 1-yr mortality rate of 64.7%; survival analysis showed that the different survival risks for short-term and long-term ventilator patients over time were not statistically significant. Long-term patients were more likely to be discharged to a nursing home (45.2%). Short-term ventilator patients had better overall quality of life at all points postdischarge. Charges to produce a long-term survivor were significantly higher than for short-term patients; on average $86,360 more charges were required to produce a long-term ventilator patient survivor for 1 yr postdischarge. CONCLUSIONS: There were no significant demographic or clinical differences between short-term and long-term ventilator patients. Our results suggest that the likelihood of need for continued care in an extended-care facility for months and the risk of death during the first year postdischarge are sufficiently common features of this population and need to be included in discussions of treatment options with patients and their families.

Aged↗

PubMed2006

Short-term and long-term reproducibility of lung tumor position using active breathing control (ABC).

PURPOSE: To evaluate the short-term and long-term reproducibility of lung tumor position for scans acquired using an active breathing control (ABC) device. METHODS AND MATERIALS: Ten patients with lung cancer were scanned over three sessions during the course of treatment. For each session, two scans were acquired at deep inhale, and one scan each at half of deep inhale and at exhale. Long-term reproducibility was evaluated by comparing the same breathing state scans from two sessions, with setup variation removed by skeletal alignment. Tumor alignment was based on intensity matching of a small volume around the tumor. For short-term reproducibility, the two inhale volumes from the same session were compared. RESULTS: For the short-term reproducibility, the mean and the standard deviation (SD) of the displacement of the center of tumor were 0.0 (1.5) mm in anteroposterior (AP), 0.3 (1.4) mm in superior/inferior (SI), and 0.2 (0.7) mm in right/left (RL) directions. For long-term reproducibility, the mean (SD) were -1.3 (3.1) mm AP, -0.5 (3.8) mm SI, and 0.3 (1.6) mm RL for inhale and -0.2 (2.8) mm AP, 0.2 (2.1) mm SI, and -0.7 (1.1) mm RL for exhale. CONCLUSION: The ABC device demonstrates very good short-term and long-term reproducibility. Increased long-term variability in position, primarily in the SI and AP directions, indicates the role of tumor-directed localization in combination with breath-held immobilization.

Carcinoma, Non-Small-Cell Lung↗

PubMed1991

Comparison of the results of electrophysiologic testing after short-term and long-term treatment with amiodarone in patients with ventricular tachycardia.

The results of electrophysiologic testing after short-term and long-term treatment with amiodarone were compared in 71 patients with ventricular tachycardia. Electrophysiologic testing was performed in the baseline state after 11 +/- 3 days of treatment with 1.2 to 2.4 gm/day of amiodarone, and after 13 +/- 4 weeks of therapy with a daily amiodarone dose of 400 mg. After short-term therapy, 62% of the patients had an adequate response to amiodarone. In 27 patients who were hemodynamically unstable, ventricular tachycardia was induced and became noninducible or hemodynamically stable after combination therapy with a class I agent. Among 18 patients who did not have inducible ventricular tachycardia after short-term therapy, eight (44%) had inducible, hemodynamically unstable ventricular tachycardia after long-term treatment with amiodarone. On the other hand, six of the 27 patients who had hemodynamically unstable ventricular tachycardia after short-term therapy had an adequate response after long-term treatment with amiodarone. Therefore an adequate electrophysiologic response after short-term therapy does not guarantee a similar response after long-term treatment, and an inadequate response after short-term therapy does not always predict a similar response after long-term therapy.

Aged↗

PubMed1994

In vitro short-term and long-term cytotoxicity of fluoroquinolones on murine cell lines.

Short-term and long-term cytotoxicity of four fluoroquinolones (ciprofloxacin, rufloxacin, ofloxacin, lomefloxacin) on 7 established murine cell lines (WEHI-3B, L1210, EL4, P388D1, 32DC13, L929, SR-4987) by a microtiter MTT assay have been studied. In short-term cytotoxic test (24 hr), cell lines with a high proliferating cell rate (as leukemias) showed a greater sensitivity to quinolones than other cell lines. In long-term cytotoxic test (7 days) no different sensitivity was observed among the cell lines. In short-term test ciprofloxacin and rufloxacin were more toxic than lomefloxacin and ofloxacin whereas in the long-term test the activity of the four quinolones was similar. Ratio between IC50 on cell lines and MIC50 against gram negative bacteria evidenced remarkable differences when short-term or long-term cytotoxic tests were considered. The results confirm toxic activity of quinolones on mammalian cells evidencing that the sensitivity to quinolones, in short-term cytotoxic test, correlates with the doubling time of cell population. The results further suggest that long-term cytotoxic tests measure better the antiproliferating activity of quinolones providing a more powerful assay to investigate their in vitro toxicity.

Animals↗

PubMed1998

Predictors of progression in long-term nonprogressors. Australian Long-Term Nonprogressor Study Group.

It is now apparent that a proportion of individuals (5-8%) remains clinically free of HIV-1 disease with normal levels of CD4+ lymphocytes (> or =500/microl) for more than 8 years following infection. However, the proportion of these individuals who ultimately progress to AIDS remains to be established. We determined the virological and immunological characteristics of a cohort of long-term nonprogressors in Australia and examined the role of these factors in predicting disease progression. Individuals with documented asymptomatic HIV-1 infection for at least 8 years with CD4+ lymphocyte counts >500 cells/microl were recruited from hospital clinics and general practices serving the eastern area of Australia. CD4+ lymphocyte count, rate of CD4+ lymphocyte change, CD8+ lymphocyte count, beta2-microglobulin, immune complex dissociated (ICD) HIV-1 p24 antigen, and plasma HIV-1 RNA were measured at baseline and multiple visits at 6-month intervals over an average period of 2 years. Up to November 1996, 67 study participants were recruited, of whom 72% had been infected with HIV-1 for at least 10 years. HIV-1 RNA correlated with beta2-microglobulin, ICD p24 antigen, and the ability to isolate virus in culture but not with levels of CD4+ or CD8+ lymphocytes. Serum beta2-microglobulin was a stronger predictor of CD4+ lymphocyte decline than HIV-1 RNA and the only factor significantly associated with CD4+ lymphocyte decline. These findings show that the serum concentration of beta2-microglobulin is a strong predictor of immunological progression in people with long-term asymptomatic HIV-1 infection and provides additional prognostic information to HIV-1 RNA in determining the risk of disease progression.

Adolescent↗

PubMed1987

Proliferation, hormonal responsiveness, and estrogen receptor content of MCF-7 human breast cancer cells grown in the short-term and long-term absence of estrogens.

We have examined the effect of short-term and long-term growth in the absence of estrogens on the proliferation rate and estrogen and antiestrogen responsiveness of MCF-7 human breast cancer cells. The removal of phenol red, the pH indicator in tissue culture medium that is weakly estrogenic (Y. Berthois et al., Proc. Natl. Acad. Sci. USA, 83:2496-2500, 1986), immediately slows the cell proliferation rate, and MCF-7 cells grown in phenol red-free medium with charcoal dextran-treated serum for periods up to 1 mo maintain this reduced rate of cell proliferation. In these short-term phenol red-withdrawn cells, estradiol stimulates proliferation markedly and reproducibly, and antiestrogens inhibit estrogen-stimulated proliferation. Antiestrogens by themselves appear as partial agonists/antagonists; at low concentrations they stimulate proliferation weakly, but they show no stimulation at the high concentrations where they fully inhibit estrogen-stimulated proliferation. In contrast to the short-term phenol red-withdrawn cells, cells maintained for several months (5 to 6 mo) in the apparently complete absence of estrogens (no phenol red, with charcoal dextran-treated calf serum) show a markedly increased basal rate of cell proliferation; estradiol is unable to increase this rate of proliferation further, but antiestrogens are able to decrease proliferation. This change in growth pattern is associated with a 3-fold increase in cellular estrogen receptor levels. Despite their differing basal growth rates, cells grown in either the short-term (less than 1 mo) or long-term (greater than 6 mo) absence of estrogens both have progesterone receptor levels that are very low and, in both cases, estradiol increases progesterone receptor levels markedly. Thus, under long-term estrogen-free conditions, there is a dissociation between the stimulation of cell proliferation and of specific protein synthesis (progesterone receptor) by estrogen. The increase in the cell proliferation rate observed in cells grown in the long-term absence of estrogen may reflect altered regulation of growth factor production or altered sensitivity to growth factors in the medium or produced by the cells themselves. Hence, these breast cancer cells adapt significantly to long-term growth in estrogen-free conditions, an observation that may be relevant to understanding the growth of hormone-responsive human breast cancers in vivo.

Breast Neoplasms↗

PubMed2004

A bridge from short-term to long-term left ventricular assist device--experimental verification of a physiological controller.

A physiological controller is a key component to optimize the performance of left ventricular assist devices (LVADs) from short term to long term (10-20 years). The difficulties of its design lie in the inaccurate modeling of any particular human cardiovascular system because of limited knowledge, the large fluctuation of systemic parameters in normal daily life, nonlinearity introduced by one-way heart valves, and restriction on available sensors. The desired physiological controller for a permanent LVAD is expected to handle different activity levels such as sleeping, resting and exercising, and different pathological levels of left ventricular failure. In this study, a physiological controller designed for a long-term continuous flow (CF) LVAD was tested in a mock circulatory loop. The pressure head across the LVAD and motor signals were used as feedback signals, which were obtained from long-term reliable sensors. Three activities and five different pathological levels of left ventricular failure were simulated to test the performance of the designed controller. The experimental results showed that the designed controller restored the total peripheral flow and arterial pressure, and decreased the left ventricular end-diastolic pressure to a safe range. The suction of the left ventricle was successfully reversed by the designed controller. The controller thus was proven to be able to control the LVAD properly in many of the possible physiological conditions experienced by LVAD recipients in long term.

Biomedical Engineering↗