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Mechanical Support (mechanical + support)
Selected AbstractsMechanical Support for Postcardiotomy Cardiogenic Shock: Has Progress Been Made?JOURNAL OF CARDIAC SURGERY, Issue 4 2010Erik A. Sylvin M.D. A previous review of this topic by our group suggested that regardless of device, only 25% of patients survived to hospital discharge. In the interim, newer technologies have entered the clinical arena. Additional contributions have been made to the literature and new databases are collecting data that are likely to provide more robust guidance for the management of these very complex patients. In this review, we update the experience of mechanical support in the PCCS patient and provide a strategy to maximize survival for a patient who develops PCCS in the community cardiac surgery center. (J Card Surg 2010;25:442-454) [source] Mechanical Support for Patients with End-Stage Heart Failure during Noncardiac Surgical ProceduresJOURNAL OF CARDIAC SURGERY, Issue 2 2010Michael K. Pasque M.D. (J Card Surg 2010;25:236-237) [source] Dr. Akif Ündar Named Co-Editor of Pediatric Mechanical SupportARTIFICIAL ORGANS, Issue 10 2009Paul S. Malchesky D.Eng. No abstract is available for this article. [source] Coronary Hemodynamics and Myocardial Oxygen Consumption During Support With Rotary Blood PumpsARTIFICIAL ORGANS, Issue 1 2009Peter Voitl Abstract Mechanical support offered by rotary pumps is increasingly used to assist the failing heart, although several questions concerning physiology remain. In this study, we sought to evaluate the effect of left-ventricular assist device (VAD) therapy on coronary hemodynamics, myocardial oxygen consumption, and pulmonary blood flow in sheep. We performed an acute experiment in 10 sheep to obtain invasively measured coronary perfusion data, as well as pressure and flow conditions under cardiovascular assistance. A DeBakey VAD (MicroMed Cardiovascular, Inc., Houston, TX, USA) was implanted, and systemic and coronary hemodynamic measurements were performed at defined baseline conditions and at five levels of assistance. Data were measured when the pump was clamped, as well as under minimum, maximum, and moderate levels of assistance, and in a pump-off condition where backflow occurs. Coronary flow at the different levels of support showed no significant impact of pump activity. The change from baseline ranged from ,10.8% to +4.6% (not significant [n.s.]). In the pulmonary artery, we observed a consistent increase in flow up to +4.5% (n.s.) and a decrease in the pulmonary artery pressure down to ,14.4% (P = 0.004). Myocardial oxygen consumption fell with increasing pump support down to ,34.6% (P = 0.008). Left-ventricular pressure fell about 52.2% (P = 0.016) as support was increased. These results show that blood flow in the coronary arteries is not affected by flow changes imposed by rotary blood pumps. An undiminished coronary perfusion at falling oxygen consumption might contribute to cardiac recovery. [source] Intra-aortic Balloon Pump Use in the Failing Fontan CirculationCONGENITAL HEART DISEASE, Issue 1 2008Adrian M. Moran MB ABSTRACT Acute cardiogenic shock in patients with Fontan physiology, while uncommon, is associated with devastating outcomes. Management of these patients is increasingly relying on the use of mechanical support. The use of intra-aortic balloon pump is underutilized. This report highlights the successful use of this modality in an adult with Fontan physiology and reviews the literature on this approach in such patients. [source] Polydivinylbenzene/Ethylvinylbenzene Composite Membranes for the Optimization of a Whole Blood Glucose SensorELECTROANALYSIS, Issue 1 2006Kerry Bridge Abstract A novel ultra thin polydivinylbenzene/ethylvinylbenzene composite membrane has been developed for use as the outer covering barrier in a model amperometric glucose oxidase enzyme electrode. The composite membrane was formed via the cathodic electropolymerization of divinylbenzene/ethylvinylbenzene at the surface of gold sputter coated host alumina membranes, (serving solely as a mechanical support for the thin polymer film). Permeability coefficients were determined for the enzyme substrates, O2 and glucose, across composite membranes formed with a range of polymer thicknesses. Due to the highly substrate diffusion limiting nature of the composite membrane, it was found that anionic interferents present in blood (such as ascorbate), were effectively screened from the working electrode via a charge exclusion mechanism, in a manner similar to previous findings within our laboratory. The enzyme electrode showed an initial 32% signal drift when first exposed to whole human blood over a period of 2 hours, after which time enzyme electrode responses remained essentially stable. Whole blood patient glucose determinations yielded a correlation coefficient of r2=0.97 in comparison to standard hospital analyses. [source] Dentinogenic potential of the dental pulp: facts and hypothesesENDODONTIC TOPICS, Issue 1 2007DIMITRIOS TZIAFAS The aim of the present article is to discuss observations and hypotheses from different experimental approaches on the biological mechanisms underlying initiation of tertiary dentin formation and therapeutic control of pulp,dentinal regeneration. The specific dentinogenic potential of dental pulp cells in up-regulating the biosynthetic activity of primary odontoblasts (reactionary dentinogenesis) and differentiation into odontoblast-like cells (reparative dentinogenesis) is described. The role of biologically active matrices and molecules as signaling factors in the expression of the dentinogenic potential of dental pulp cells, in numerous ex vivo and in vivo models, is reviewed. Data are focused on the mechanisms by which the signaling molecules, in the presence of the appropriate pulp microenvironment and specific mechanical support, can induce competent pulpal cells in the acquisition of odontoblast-like cell phenotype and reparative dentin formation. The ability of tissue engineering to stimulate reconstruction of the amputated pulp,dentin complex offers exciting opportunities for the future. Advances in molecular biology and bioengineering research might thus be integrated into the clinical problems of endodontology. Received 13 February 2009; accepted 2 September 2009. [source] Murray's law and the hydraulic vs mechanical functioning of woodFUNCTIONAL ECOLOGY, Issue 6 2004K. A. McCULLOH Summary 1Murray's law states that the hydraulic conductance per blood volume of the cardiovascular system is maximized when the sum of the vessel radii cubed (, r3) is conserved. 2We hypothesize that Murray's law will apply to xylem conduits as long as they only transport water and do not also help support the plant. Specifically, the less volume of wood occupied by conduits, the more the conduits should conform to Murray's law. 3We tested the applicability of Murray's law along a continuum of decreasing conduit fraction from coniferous (91% conduits) to diffuse-porous (24% conduits) to ring-porous wood (12% conduits), using anatomical and functional tests. The anatomical test compared the , r3 conservation across branch points by direct measurements of conduit radii. The functional test compared the hydraulic conductivity between branches of different ages. 4As predicted, Murray's law was rejected in conifer wood where hydraulic function is coupled to mechanical support. The angiosperm wood did not deviate as strongly from Murray's law, especially the ring-porous type. For comparison we report previously published results from compound leaves and vines which showed general agreement with Murray's law. 5Deviation from Murray's law was associated with fewer, narrower conduits distally causing a decrease in , r3 distally. Although less efficient hydraulically, this configuration is not top-heavy and is more mechanically stable. With the evolution of vessels and fibres, angiosperm wood can more closely approach Murray's law while still meeting mechanical requirements. [source] The extracellular matrix can regulate vascular cell migration, proliferation, and survival: relationships to vascular diseaseINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 3 2000Elaine W. Raines The extra cellular matrix (ECM) of the normal artery wall is a collection of fibrous proteins and associated glycoproteins embedded in a hydrated ground substance of glycosaminoglycans and proteoglycans. These distinct molecules are organized into a highly ordered network that are closely associated with the vascular cells that produce them. In addition to providing the architectural framework for the artery wall that imparts mechanical support and viscoelasticity, the ECM can regulate the behaviour of vascular cells, including their ability to migrate, proliferate and survive injury. The composition of the ECM is different within intimal lesions of atherosclerosis, which are composed of monocytes and lymphocytes from the circulation and smooth muscle cells (SMC) that migrate from the media to the intima ( Ross 1993, 1999), and these differences may contribute to the altered phenotype of vascular cells within lesions. This review will briefly outline the ECM changes observed in atherosclerosis and restenosis and the potential relationship of these changes to altered vascular cell functions. [source] Mechanical Support for Postcardiotomy Cardiogenic Shock: Has Progress Been Made?JOURNAL OF CARDIAC SURGERY, Issue 4 2010Erik A. Sylvin M.D. A previous review of this topic by our group suggested that regardless of device, only 25% of patients survived to hospital discharge. In the interim, newer technologies have entered the clinical arena. Additional contributions have been made to the literature and new databases are collecting data that are likely to provide more robust guidance for the management of these very complex patients. In this review, we update the experience of mechanical support in the PCCS patient and provide a strategy to maximize survival for a patient who develops PCCS in the community cardiac surgery center. (J Card Surg 2010;25:442-454) [source] Fungemia Associated with Left Ventricular Assist Device SupportJOURNAL OF CARDIAC SURGERY, Issue 6 2009M.P.H., Natasha G. Bagdasarian M.D. While relatively uncommon, fungal infections present a serious concern given a high association with adverse events including death. We sought to further characterize the epidemiology of fungemias during LVAD support. Methods: Retrospective review of 292 patients receiving LVAD support from October 1996 to April 2009 at the University of Michigan Health System was done. Results: Seven cases of LVAD-associated fungemia were observed during the study period (0.1 infections/1000 days of device support). Five patients had infection with Candida species and two with Aspergillus species. The two patients with Aspergillus infection presented with disseminated disease, quickly dying of multiorgan failure, and sepsis. All five patients with Candida infections were successfully treated with systemic antifungal therapy along with transplantation in four of five patients. The fifth patient is receiving mechanical support as destination therapy. He remains on long-term suppression with high-dose fluconazole. Conclusions: Fungal infections appear to be a rare but serious complication of LVAD support. Future studies should aim to improve our understanding of risk factors for fungal infection during mechanical support, especially disseminated Aspergillus. Short-term perioperative antifungal prophylaxis with fluconazole appears to be an effective and reasonable approach to prevention. [source] AB-polymer Networks with Cooligoester and Poly(n -butyl acrylate) Segments as a Multifunctional Matrix for Controlled Drug ReleaseMACROMOLECULAR BIOSCIENCE, Issue 9 2010Christian Wischke Abstract Semi-crystalline AB-copolymer networks from oligo[(, -caprolactone)- co -glycolide]dimethacrylates and n -butylacrylate have recently been shown to exhibit a shape-memory functionality, which may be used for self-deploying and anchoring of implants. In this study, a family of such materials differing in their molar glycolide contents ,G was investigated to determine structure,property functional relationships of unloaded and drug loaded specimens. Drug loading and release were evaluated, as well as their degradation behavior in vitro and in vivo. Higher ,G resulted in higher loading levels by swelling and a faster release of ethacridine lactate, lower melting temperature of polymer crystallites, and a decrease in shape fixity ratio of the programmed temporary shape. For unloaded networks, the material behavior in vivo was independent of the mechanical load associated with different implantation sites and agreed well with data from in vitro degradation studies. Thus, AB networks could be used as novel matrices for biofunctional implants, e.g., for urogenital applications, which can self-anchor in vivo and provide mechanical support, release drugs, and finally degrade in the body to excretable fragments. [source] Progress in single-walled carbon nanotube based nanoelectromechanical systemsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 13 2006Jannik C. Meyer Abstract We present torsional pendulums based on small bundles of single-walled carbon nanotubes and ultimately on individual single-walled carbon nanotubes. The nanotubes serve as mechanical support and torsional spring for a lithographically defined metal plate. The plate can be actuated in an electric field and the device is operated inside the transmission electron microscope. In comparison with previous works we have built mechanically much more fragile devices, i.e. almost three orders of magnitude heavier suspended metal structures, and metal blocks suspended on smaller diameter nanotubes. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Recent Trends in Early Outcome of Adult Patients after Heart Transplantation: A Single-institution Review of 251 Transplants Using Standard Donor Organs,AMERICAN JOURNAL OF TRANSPLANTATION, Issue 6 2002Feng-Chun Tsai Older age, prior transplantation, pulmonary hypertension, and mechanical support are commonly seen in current potential cardiac transplant recipients. Transplants in 436 consecutive adult patients from 1994 to 1999 were reviewed. There were 251 using standard donors in 243 patients (age range 18,69 years). To emphasize recipient risk, 185 patients who received a nonstandard donor were excluded from analysis. The indications for transplant were ischemic heart disease (n = 123, 47%), dilated cardiomyopathy (n = 82, 32%), and others (n = 56, 21%). One hundred and forty-nine (57%) recipients were listed as status I; 5 and 6% were supported with an intra-aortic balloon and an assist device, respectively. The 30-d survival and survival to discharge were 94.7 and 92.7%, respectively; 1-year survival was 89.1%. Causes of early death were graft failure (n = 6), infection (n = 4), stroke (n = 4), multiorgan failure (n = 3) and rejection (n = 2). Predictors were balloon pump use alone (OR = 11.4, p =,0.002), pulmonary vascular resistance > 4 Wood units (OR = 5.7, p =,0.007), pretransplant creatinine > 2.0 mg/dL (OR = 6.9, p =,0.004) and female donor (OR = 8.3, p =,0.002). Recipient age and previous surgery did not affect short-term survival. Heart transplantation in the current era consistently offers excellent early and 1-year survival for well-selected recipients receiving standard donors. Early mortality tends to reflect graft failure while hospital mortality may be more indicative of recipient selection. [source] Atrial Versus Ventricular Cannulation for a Rotary Ventricular Assist DeviceARTIFICIAL ORGANS, Issue 9 2010Daniel Timms Abstract The ventricular assist device inflow cannulation site is the primary interface between the device and the patient. Connecting these cannulae to either atria or ventricles induces major changes in flow dynamics; however, there are little data available on precise quantification of these changes. The objective of this investigation was to quantify the difference in ventricular/vascular hemodynamics during a range of left heart failure conditions with either atrial (AC) or ventricular (VC) inflow cannulation in a mock circulation loop with a rotary left VAD. Ventricular ejection fraction (EF), stroke work, and pump flow rates were found to be consistently lower with AC compared with VC over all simulated heart failure conditions. Adequate ventricular ejection remained with AC under low levels of mechanical support; however, the reduced EF in cases of severe heart failure may increase the risk of thromboembolic events. AC is therefore more suitable for class III, bridge to recovery patients, while VC is appropriate for class IV, bridge to transplant/destination patients. [source] Initial Clinical Experience With the HeartMate II Ventricular Assist System in a Pediatric InstitutionARTIFICIAL ORGANS, Issue 7 2010William R. Owens Abstract In many adult cardiac programs, intracorporeal mechanical circulatory support has become a routine treatment for end-stage cardiac failure. For the pediatric population, options are often limited by a small body habitus. Even when an adolescent's weight may suggest adequate space for device implant, most intracorporeal adult devices remain too large for adolescents. The Thoratec HeartMate II (HM II) (approved by the FDA in April of 2008) is a small, noiseless device that is easily operated and monitored. By having an uncomplicated operating system and small percutaneous drive line, the HM II provides an opportunity for these patients to aggressively rehabilitate to become a better transplant candidate and also provides the potential to be discharged home. The two youngest patients ever to utilize the HM II are also the first two cases of using the HM II at a freestanding pediatric hospital. A 12-year-old, 53 kg, girl with dilated cardiomyopathy was supported for 85 days before receiving her heart transplant. The second patient, a 13-year-old, 149 kg, Hispanic male suffering from morbid obesity and dilated cardiomyopathy, was supported for 128 days. The HM II allowed for rehabilitation and nutritional education, resulting in this patient losing 50 kg before heart transplant. Despite both of these patients' size, their thoracic cavities were that of a preadolescent and thus techniques were developed to avoid morbidities like chest wall abrasion and bleeding. Because of differences between adult and pediatric patients and institutions, these cases provided unique challenges. However, as pediatric device therapy is now maturing, pediatric programs such as Texas Children's Hospital have begun to develop strategies for mechanical support that factor in patient's size and need for long-term or temporary support, utilizing the growing number of devices (i.e., Jostra Rotoflow, Tandem Heart PTVA, Thoratec CentriMag, Berlin Heart EXCOR, etc.) that are now available to children. [source] Extracorporeal Life Support: A Simple and Effective Weapon for Postcardiotomy Right Ventricular FailureARTIFICIAL ORGANS, Issue 7 2009Kuo-Sheng Liu Abstract Postcardiotomy right ventricular (RV) failure develops during the perioperative period following pulmonary hypertensive crisis or acute myocardial infarction. This study reports our institutional experience in treating these patients with extracorporeal life support (ECLS). Between June 2002 and July 2005, 46 adults were treated with ECLS for postcardiotomy shock. Acute RV failure was the cause of support in 14 (30%). Patient mean age was 55.7 ± 15.4 years. Cardiac pathologies were valvular (n = 7), coronary (n = 1), combined coronary and valvular disease (n = 2), complex congenital heart (n = 2), aortic aneurysm (n = 1), and cardiomyopathy post heart transplant (n = 1). The triggers of RV failure were pulmonary hypertension (n = 6), RV infarction (n = 4), and not defined (n = 4). Patients were supported on ECLS for a mean duration of 71 ± 52 h (range, 10,183 h). Major complications included acute renal failure requiring hemodialysis (n = 4), reexploration for bleeding (n = 2), and acute subdural hematoma (n = 1). Nine (64%) patients were successfully weaned from ECLS, and seven (50%) survived to discharge. Preexisting pulmonary hypertension had a favorable tendency for weaning, and acute renal failure requiring hemodialysis correlated with in-hospital mortality. ECLS is beneficial for treating postcardiotomy RV failure when conventional therapy is exhausted. As it can be deployed rapidly and does not require resternotomy for weaning, ECLS could be regarded as the first choice of mechanical support for postcardiotomy RV failure. [source] An overview of the dental pulp: its functions and responses to injuryAUSTRALIAN DENTAL JOURNAL, Issue 2007C. Yu Abstract The dental pulp is a unique tissue and its importance in the long-term prognosis of the tooth is often ignored by clinicians. It is unique in that it resides in a rigid chamber which provides strong mechanical support and protection from the microbial rich oral environment. If this rigid shell loses its structural integrity, the pulp is under the threat of the adverse stimuli from the mouth, such as caries, cracks, fractures and open restoration margins, all of which provide pathways for micro-organisms and their toxins to enter the pulp. The pulp initially responds to irritation by becoming inflamed and, if left untreated, this will progress to pulp necrosis and infection. The inflammation will also spread to the surrounding alveolar bone and cause periapical pathosis. The magnitude of pulp-related problems should not be underestimated since their most serious consequence is oral sepsis, which can be life threatening, and hence correct diagnosis and management are essential. Clinicians must have a thorough understanding of the physiological and pathological features of the dental pulp as well as the biological consequences of treatment interventions. [source] Dobutamine as bridge to angiotensin-converting enzyme inhibitor-nitrate therapy in endstage heart failureCLINICAL CARDIOLOGY, Issue 3 2001T. Barry Levine M.D. Abstract Background: Intravenous inotropic intervention in congestive heart failure is generally associated with a poor prognosis and is largely used as a "bridge" to mechanical support or heart transplantation. Hypothesis: We hypothesized that the inotropic support afforded by dobutamine may serve as a bridge to the introduction and intensification of angiotensin-converting enzyme (ACE) inhibitor-nitrate therapy. Methods: We studied the efficacy of transitioning inotrope-dependent patients in endstage heart failure from intravenous dobutamine to high-dose ACE inhibitor-nitrates, with 1-year follow-up. Forty-nine sequential dobutamine-dependent patients with left ventricular ejection fraction (LVEF) 17 ± 17% were treated with increasing lisinopril (1.9 ± 1.5 to 46 ± 28 mg/day) and isosorbide dinitrate (7 ± 6 to 229 ± 161 mg/day). Outpatient dobutamine was continued or repeat infusions pursued, as indicated, and dobutamine was tapered when feasible. Results: During the following year, 14 of 49 patients required repeat dobutamine, with home treatment with dobutamine for 6.3 ± 3.7 months (n = 5). At 1 year, New York Heart Association (NYHA) classification improved from 3.6 ± 0.5 to 1.9 ± 1.0, p < 0.0001; yearly hospitalizations fell from 2.7 ± 2.3 to 1.2 ± 3.0, p = 0.02; and LVEF rose from 17 ± 7% to 24 ± 11%, p < 0.0001. At 1 year, 14 patients who remained dobutamine dependent had significantly more severe symptoms than dobutamine-independent patients (n = 35). Transplant or death occurred in 7 of 14 patients with follow-up dobutamine, and in 5 of 35 patients free of subsequent dobutamine, p = 0.03. Patients with poor outcome (transplant n = 10, death n = 12) continued to be more limited (NYHA 2.7 ± 0.9 vs. 1.7 ± 0.9, p = 0.0002), with more follow-up hospitalizations (3.6 ± 5.4 vs. 0.6 ± 0.8, p = 0.0004), and no improvement in LVEF (17 ± 8 vs. 28 ± 11%, p = 0.003). Conclusions: Of the patients on dobutamine inotropic support, 70% were successfully transitioned to ACE inhibitor-nitrate therapy, with improved symptoms and LVEF, and with reduced hospitalizations and follow-up dobutamine or transplant. Thirty percent of patients with continued need for dobutamine had a significantly poorer 1-year clinical outcome. [source] | |||||||||||||