Current status of device-assisted enteroscopy: Technical matters, indication, limits and complications

Enteroscopy, defined as direct visualization of the smallbowel with the use of a fiberoptic or capsule endoscopy, has progressed considerably over the past severalyears. The need for endoscopic access to improvediagnosis and treatment of small bowel disease hasled to the development of novel technologies one ofwhich is noninvasive, the video capsule, and a type of invasive technique, the deviceassisted enteroscopy.In particular, the device-assisted enteroscopy consiststhen of three different types of instruments all able toallow, in skilled hands, to display partially or throug-hout its extension (if necessary) the small intestine.Newer devices, double balloon, single balloon and spiral endoscopy, are just entering clinical use. The aim of this article is to review recent advances in small bowelenteroscopy, focusing on indications, modifications toimprove imaging and techniques, pitfalls, and clinical applications of the new instruments. With new technologies, the trials and tribulations of learning new endo-scopic skills and determining their role in the diagnosisand treatment of small bowel disease come. Identification of small bowel lesions has dramatically improved.Studies are underway to determine the best strategy toapply new enteroscopy technologies for the diagnosisand management of small bowel disease, particularly obscure bleeding. Vascular malformations such as angiectasis and small bowel neoplasms as adenocar cinomaor gas trointestinal stromal tumors. Complete entero-scopy of the small bowel is now possible. However, because of the length of the small bowel, endoscopic examination and the rapeutic maneuvers require significant skill, radiological assistance, the use of deep sedation with the assistance of the anesthetist. Prospective ran-domized studies are needed to guide diagnostic testing and the rapy with these new endoscopic techniques.

Combined Application of Circulatory Assist Devices Following Cardiac Arrest in Patients after Cardiac Surgery

Objectives To evaluate retrospectively the potential benefits of combined utilization of various assisted circulation devices in cardiac arrest patients who did not respond to conventional cardiopulmonary cerebral resuscitation （CPCR）. Methods Assisted circulation devices, including emergency cardiopulmonary bypass （ECPB）, intra-aortic balloon pump （IABP）, and left ventricular assist device （LVAD）, were applied to 16 adult patients who had cardiac arrest 82 rain-56 h after open heart surgery and did not respond to 20 rain or longer conventional CPCR. ECPB was applied to 2 patients, ECPB plus IABP to 8 patients, ECPB plus IABP and LVAD to 6 patients. Results One patient recovered fully and one patient died. Of the other 14 patients, 13 resumed spontaneous cardiac rhythm and one did not; none of them could be weaned from ECPB. Further treatment of the 14 patients with combinations of assisted circulation devices enabled 6 patients to recover. One of the 7 recovered patients died of reoccurring cardiac arrest after 11 days; the other 6 were discharged in good condition and were followed up for 3-49 months （mean =22 months）. Of the 6 discharged patients one suffered cerebral embolism during LVAD treatment, resulting in mild limitation of mobility of the right limbs ; the other 5 never manifested any central nervous system complications. There was no late deaths giving a 37.5% （6/16） long-term survival rate. Conclusions ECPB could effectively reestablish blood circulation and oxygen supply, rectify acidosis, and improve internal milieu. The combined utilization of ECPB, IABP, and LVAD reduces the duration of ECPB, improves the incidence of recovery, and offers beneficial alternatives to refractory cardiac arrest patients.

Short and long term outcomes of 200 patients supported by continuous-flow left ventricular assist devices

AIM: To study the institutional experience over 8 years with 200 continuous-flow(CF)- left ventricular assist devices(LVAD).METHODS: We evaluated our institution's LVAD database and analyzed all patients who received a CF LVAD as a bridge to transplant(BTT) or destination therapy from March 2006 until June 2014. We identified 200 patients, of which 179 were implanted with a Heart Mate II device(Thoratec Corp., Pleasanton, CA) and 21 received a Heartware HVAD(Heart Ware Inc., Framingham, MA).RESULTS: The mean age of our LVAD recipients was 59.3 years(range 17-81), 76%(152/200) were males, and 49% were implanted for the indication of BTT. The survival rate for our LVAD patients at 30 d, 6 mo, 12 mo, 2 years, 3 years, and 4 years was 94%, 86%, 78%, 71%, 62% and 45% respectively. The mean duration of LVAD support was 581 d(range 2-2595 d). Gastrointestinal bleeding(was the most common adverse event(43/200, 21%), followed by right ventricular failure(38/200, 19%), stroke(31/200, 15%), re exploration for bleeding(31/200, 15%),ventilator dependent respiratory failure(19/200, 9%) and pneumonia(15/200, 7%). Our driveline infection rate was 7%. Pump thrombosis occurred in 6% of patients. Device exchanged was needed in 6% of patients. On multivariate analysis, preoperative liver dysfunction, ventilator dependent respiratory failure, tracheostomy and right ventricular failure requiring right ventricular assist device support were significant predictors of post LVAD survival.CONCLUSION: Short and long term survival for patients on LVAD support are excellent, although outcomes still remain inferior compared to heart transplantation. The incidence of driveline infections, pump thrombosis and pump exchange have declined significantly in recent years.

Left ventricular assist devices as destination therapy in stage D heart failure

1 Introduction? Mechanical circulatory support (MCS) has increasingly become an important management opportunity for patients with stage D heart failure (HF) with remarkable impact on patient survival and quality of life. Early clinical trials have demonstrated improved outcomes of durable left ventricular assist device (LVAD) support compared with optimal medical management.[1] As technology advanced, continuous flow LVADs outperformed pulsatile flow devices in clinical trials and the field migrated to HeartMate (Abbott Laboratories, Abbott Park, IL) and HeartWare (Medtronic, Minneapolis, MN) devices due to their clinical superiority. Among the continuous flow devices.

Cap-assisted endoscopy for esophageal foreign bodies:A metaanalysis

BACKGROUND Esophageal foreign bodies are common around the world.Newer approaches,such as cap-assisted endoscopy,have been introduced as an alternative to conventional methods.Therefore,we performed a meta-analysis ono cap-assisted endoscopy versus conventional endoscopy for removal of esophageal foreign bodies.AIM To investigated the effectiveness of cap-assisted endoscopy with conventional endoscopy.METHODS An extensive literature search was performed(December 2021).For esophageal foreign body removal,cap-assisted endoscopy was compared to conventional endoscopy for procedure time,technical success of the procedure,time of foreign body retrieval,en bloc removal,and adverse event rate using odds ratio and mean difference.RESULTS Six studies met the inclusion criteria(n=1305).Higher odds of technical success(P=0.002)and en bloc removal(P<0.01)and lower odds of adverse events(P=0.02)and foreign body removal time(P<0.01)were observed with cap-assisted endoscopy as compared to conventional techniques.CONCLUSION For esophageal foreign bodies,the technique of cap-assisted endoscopy demonstrated increased en bloc removal and technical success with decreased time and adverse events as compared to conventional techniques.

In vitro evaluation of a new resilient, hard-carbon, thin-film coating as a bearing material for ventricular assist devices ——In Vitro Bearing Evaluation of BioMedFlex

Our aim was to evaluate the potential use of BioMedFlex? (BMF), a new resilient, hard-carbon, thin- film coating, as a blood journal bearing material in Cleveland Heart’s continuous-flow left and right ven- tricular assist devices (VADs). BMF is not classified as a diamond-like carbon (DLC) and differs from other thin-film carbon coatings by its high flexural strength, radiopacity, and wear resistance. A 2- to 4-μm-thick BMF adhesion layer was deposited on the VAD journal bearing surfaces. A commercial DLC coating used in other clinical blood pump applications was used as a control. Durability and reliability of the BMF coating was verified in severe pump start/stop testing using 20 BMF-coated journal bearing pairs. The BMF-coated surfaces showed no coating failures, whereas 57% of the DLC bearing pairs developed scratches through the carbon coating, documenting that BMF can provide a durable coating in our blood journal bearing application. In conclusion, BMF has shown qualities that support its significant advantages as an alternative journal bea- ring material in Cleveland Heart pumps. Our plan includes biocompatibility testing with ongoing animal studies, endurance testing with submerged pumps running in saline, and assessment of batch coating processing capability.

Comprehensive review of hemolysis in ventricular assist devices

Ventricular assist devices(VADs)have played an important role in altering the natural history of end-stage heart failure.Low-grade hemolysis has been traditionally described in patients with VADs,indicating effective device functionality.However,clinically significant hemolysis could be crucial in terms of prognosis,calling for prompt therapeutic actions.The absence of solid and widely approved diagnostic criteria for clinically significant hemolysis,render the utilization of hemolysis laboratory markers challenging.Hemolysis incidence varies(5%-18%)depending on definition and among different VAD generations,being slightly higher in continuous-flow devices than in pulsatile devices.Increased shear stress of red blood cells and underlying device thrombosis appear to be the main pathogenetic pathways.No certain algorithm is available for the management of hemolysis in patients with VADs,while close clinical and laboratory monitoring remains the cornerstone of management.Imaging examinations such as echocardiography ramp test or computed tomography scan could play a role in revealing the underlying cause.Treatment should be strictly personalized,including either pharmacological(antithrombotic treatment)or surgical interventions.

Video capsule endoscopy in left ventricular assist device recipients with obscure gastrointestinal bleeding

AIM: To assess whether video capsule endoscopy(VCE) affects the outcomes of left ventricular assist devices(LVADs) recipients with gastrointestinal bleeding.METHODS: This is a retrospective study of LVAD recipients with obscure gastrointestinal bleeding(OGIB) who underwent VCE at a tertiary medical center between 2005 and 2013. All patients were admitted and monitored with telemetry and all VCE and subsequent endoscopic procedures were performed as inpatients. A VCE study was considered positive only when P2 lesions were found and was regarded as negative if P1 or P0 were identified. All patients were followed until heart transplant, death, or the end of the study.RESULTS: Between 2005 and 2013, 30 patients with LVAD underwent VCE. Completion rate of VCE was 93.3% and there was no capsule retention. No interference of VCE recording or the function of LVAD was found. VCE was positive in 40% of patients(n = 12). The most common finding was active small intestinal bleeding(50%) and small intestinal angiodysplasia(33.3%). There was no difference in the rate of recurrent bleeding between patients with positive and negative VCE study(50.0% vs 55.6%,P = 1.00) during an average of 11.6 ± 9.6 mo follow up. Among patients with positive VCE, the recurrent bleeding rate did not differ whether subsequent endoscopy was performed(50% vs 50%, P = 1.00).CONCLUSION: VCE can be safely performed in LVAD recipients with a diagnostic yield of 40%. VCE does not affect recurrent bleeding in LVAD patients regardless of findings.

Left ventricular assist device hemolysis leading to dysphagia

A 41-year-old man with a continuous- flow left ventricular assist device presented for evaluation of dysphagia and dark urine. He was found to have a significantly elevated L-lactate dehydrogenaseand an elevated plasma free hemoglobin consistent with intravascular hemolysis.After the hemolysis ceased,both the black urine and dysphagia resolved spontaneously.Transient esophageal dysfunction,as a manifestation of gastrointestinal dysmotility,is known to occur in the setting of hemolysis.Paroxysmal nocturnal hemoglobinuria is another recognized cause of massive hemolysis with gastrointestinal dysmotility occurring in25%-35%of patients during a paroxysm.Intravascular hemolysis increases plasma free hemoglobin,which scavenges nitric oxide(NO),an important second messenger for smooth muscle cell relaxation.The decrease in NO can lead to esophageal spasm and resultant dysphagia.In our patient the resolution of hemolysis resulted in resolution of dysphagia.

Resolution of hemolysis from pump thrombus during left ventricular assist device exchange

A 50-year-old male who underwent a Heart Mate Ⅱ left ventricular assist device placement for ischemic cardiomyopathy presented with discolored urine and hemolysis 3 mo after the operation. His hemolysis was thought to be due to thrombosis within the pump. Imaging studies were not able to visualize a left ventricular thrombus. Medical management with anticoagulation failed and he underwent surgery for a pump exchange. Intraoperatively, a firm thrombus was found within the pump of the Heart Mate Ⅱ, and the color of the urine changed dramatically from cola-colored to yellow which enabled us to confirm the diagnosis.

Gastrointestinal bleeding in a patient with a continuous-flow biventricular assist device

The association between continuous-flow left ventricular assist devices(CF-LVADs)and gastrointestinal(GI)bleeding from angiodysplasia is well recognized.However,the association between continuous-flow biventricular assist devices(CF-BIVADs)and bleeding angiodysplasia is less understood.We report a case of GI bleeding from a patient with a CF-BIVAD.The location of GI bleeding was identified by nuclear red blood cell bleeding scan.The vascular malformation leading to the bleed was identified and localized on angiography and then by pathology.The intensity of bleeding,reflected by number of units of packed red blood cells needed for normalization of hemoglobin,as well as the time to onset of bleeding after transplantation,are similar to that seen in the literature for CF-LVADs and pulsatile BIVADs.While angiography only detected a dilated late draining vein,pathology demonstrated the presence of both arterial and venous dilation in the submucosa,vascular abnormalities characteristic of a late arteriovenous malformation.

Computational fluid dynamics of left ventricular assist device under unsteady flow

Left ventricular assist device( LVAD) in this study is a mechanical tool that is used to support blood flow in the patient with heart disease. It supports left ventricle by building up the pressure to the pump outlet connected to the aorta. This pump was designed based on the magnetic driven centrifugal pump with a unique small washout hole constructed inside the impeller to generate the washout flow passage to prevent the stagnation at the region underneath and around the rotor. Computational fluid dynamics( CFD) was adopted in this study to assess the performance and optimize the design to avoid recirculation and high shear stress which is the main cause of stagnation and blood damage. Transient simulation was used for this study due to the asymmetric design of the washout hole and the complication of the bottom support of the impeller that has a risk of thrombosis,also,it was used to predict the variation of hydraulic performance caused by the rotation of the impeller and pulsed flow at the pump inlet. The simulation results show no excessive stress and no recirculation observed within the computational domain; in addition,the research result also provides information for further optimization and development to the pump.

Construction of Bioartificial Renal Tubule Assist Device In Vitro and Its Function of Transporting Sodium and Glucose

To explore a new way of constructing bioartificial renal tubule assist device （RAD） in vitro and its function of transporting sodium （Na^＋） and glucose and to evaluate the application of atomic force microscope in the RAD construction, rat renal tubular epithelial cell line NRK-52E was cultured in vitro, seeded onto the outer surfaces of hollow fibers in a bioreactor, and then cultured for two weeks to construct RAD. Bioreactor hollow fibers without NRK-52E cells were used as control. The morphologies of attached cells were observed with scanning electron microscope, and the junctions of cells and polysulfone membrane were observed with atomic force microscope. Transportation of Na＋ and glucose was measured. Oubaine and phlorizin were used to inhibit the transporting property. The results showed that NRK-52E cells and polysulfone membrane were closely linked, as observed under atomic force microscope. After exposure to oubaine and phlorizin, transporting rates of Na^＋ and glucose were decreased significantly in the RAD group as compared with that in the control group （P〈0.01）. Furthermore, when the inhibitors were removed, transportation of Na^＋ and glucose was restored. It is concluded that a new RAD was constructed successfully in vitro, and it is able to selectively transport Na^＋ and glucose.

OBSERVATION AND ANALYSIS OF BLOOD CONTACTING SURFACE OF LEFT VENTRICULAR ASSIST DEVICE WITH SCANNING ELECTRON MICROSCOPY

Thrombus formation in the artificial heart blood pump is a complex problem. The most important factor of thrombosis in the blood pump is the quality of blood contacting surface which is related to hemocompatibility of materials and micromorphololgy or roughness of the surface. So it is necessary to understand the morphology of the surface inside of blood pump in order to develop and improve a good quality blood pump. The authors observed and analysed the inner surface of blood pumps (both preimplanted and postimplanted) with scanning electron microscopy (SEM) providing a means for evaluating the blood pumps and for developing good quality of blood pumps. It was observed that there were four kinds of surface defects on the inner surface of the blood pumps: air bubble domes, open bubble craters, contaminated dust and gel particles. Microcrakes had also been found on the diaphragm of the postimplanted pump. But in the newly improved blood pump that had been imlanted for 16 days, there were few defects on the blood contacting surface, and only a little fibrinous layer observed. It could be considered that the current design and modifications are reasonable. Since some problems associated with the surface defects and thrombosis still existed, further improvement in fabrication process and quality control procedures with SEM are under way.

Interest of Ventricular Assist Device in Peripartum Cardiomyopathy, a Case Report and Review Article

We report a case of severe post partum cadiomyopathy in severe cardiogenic shock, treated successfully and urgently with the implantation of Left Ventricular Assist device. The patient recovered a normal left ventricle function shortly after implantation. This case illustrates the crucial place of left ventricular assist device in severe post partum cardiomyopathy as a bridge to recovery as well as a bridge to transplantation.

Optimal timing of same-admission orthotopic heart transplantation after left ventricular assist device implantation

AIM To investigate the impact of timing of same-admission orthotopic heart transplant(OHT) after left ventricular assist device(LVAD) implantation on in-hospital mortality and post-transplant length of stay.METHODS Using data from the Nationwide Inpatient Sample from 1998 to 2011, we identified patients 18 years of age or older who underwent implantation of a LVAD and for whom the procedure date was available. We calculated in-hospital mortality for those patients who underwent OHT during the same admission as a function of time from LVAD to OHT, adjusting for age, sex, race, household income, and number of comorbid diagnoses. Finally, we analyzed the effect of time to OHT after LVAD implantation on the length of hospital stay post-transplant.RESULTS Two thousand and two hundred patients underwent implantation of a LVAD in this cohort. One hundred and sixty-four(7.5%) patients also underwent OHT duringthe same admission, which occurred on average 32 d(IQR 7.75-66 d) after LVAD implantation. Of patients who underwent OHT, patients who underwent transplantation within 7 d of LVAD implantation("early") experienced increased in-hospital mortality(26.8% vs 12.2%, P = 0.0483) compared to patients who underwent transplant after 8 d("late"). There was no statistically significant difference in age, sex, race, household income, or number of comorbid diagnoses between the early and late groups. Post-transplant length of stay after LVAD implantation was also not significantly different between patients who underwent early vs late OHT. CONCLUSION In this cohort of patients who received LVADs, the rate of in-hospital mortality after OHT was lower for patients who underwent late OHT(at least 8 d after LVAD implantation) compared to patients who underwent early OHT. Delayed timing of OHT after LVAD implantation did not correlate with longer hospital stays post-transplant.

Impact of Ventricular Assist Device Implantation on Clinical and Economic Outcomes of Heart Transplantation in the United States from 2003-2007

The use of ventricular assist devices (VADs) as a bridge to transplantation (BTT) has evolved considerably as clinical experience has grown and newer generation devices have become available. This study investigated the impact of VAD implantation on the clinical and economic outcomes of patients undergoing heart transplantation in the United States(US) from 2003-2007. A retrospective study was carried out using the Nationwide Inpatient Sample, to track the characteristics and outcomes of an estimated 7859 patients undergoing heart transplantation in the United States from 2003-2007. Patients were divided based on whether they were bridged to transplant with a VAD and whether they were outpatient (VAD Outpt) or inpatient (VAD Inpt). Multivariate analysis was performed to identify risk factors for inhospital mortality following heart transplantation. Hospital costs were also measured. A VAD was used as a BTT in 20.8% of patients undergoing heart transplantation during the study period. Early in the series the frequency of VAD Outpts and Inpts was similar but in later years patients were more commonly bridged as outpatients. Hospital mortality for the entire population was 6.2%. Multivariate analysis identified several risk factors for mortality, including advanced age, history of congenital heart disease, and VAD Inpt status. VAD Inpt status was the strongest predictor of mortality. The hospital cost of patients bridged as inpatients was more than double the cost of outpatients. Median hospital cost declined by 11% over the study period, from $115,868 to $103,578. Much of this cost reduction was related to the shift in VAD status from Inpt to Outpt. Heart transplant recipients are increasingly bridged to transplantation with VADs as outpatients. Those bridged as inpatients have substantially higher hospital mortality and cost. These findings have important clinical implications and should inform policy development, resource utilization and donor allocation.

Continuous Flow Left Ventricular Assist Device Therapy:A Focused Review on Optimal Patient Selection and Long-Term Follow-up Using Echocardiography

Despite widespread awareness and use of scientifi cally proven life-prolonging medical and device-based therapies over the last two decades,heart failure remains a leading cause of morbidity,mortality,and health care expenditure in the United States.Mechanical circulatory support with a continuous-fl ow left ventricular assist device(CF-LVAD),either as a bridge to heart transplantation or as destination therapy,is an increasingly used treatment modality for patients with advanced heart failure syndromes that worsen despite their receiving standard therapies.CF-LVAD support creates unique hemodynamic alterations that must be understood to provide appropriate care for these patients before and after implantation.Echocardiography is essential in the evaluation of patients who are being considered for or are mechanically supported by CF-LVADs.Here we provide a focused clinical review on the use of echocardiography in two main aspects of the evaluation of these patients:(a)optimal patient selection for CF-LVAD support and(b)followup assessment of optimal pump function.

A Comparison Study of Cavitating Flow in a Ventricular Assist Device Using Laminar and Turbulent Model

The two-dimensional cavitating flow phenomena due to the valve closure in a ventricular assist device were computationally studied. This is a simplification of three-dimensional viscous effects in a ventricular valve. Both laminar flow and turbulent flow were computed and compared with each other. For computations, a dynamic mesh strategy to cope with the movement of the valve was developed. The simulation of cavitation was conducted with a model which took considerations of the first-order effect of the formation and transport of vapor bubbles, the turbulent fluctuations of pressure and velocity, and the magnitude of non-condensable gases. The turbulent flow was computed by using thek-wmodel. The results show that the local turbulence is one of the vital effects on the development of the cavitating flow. The maximum velocity at the moments of valve closure was significantly reduced in the turbulent flow modeling. Turbulence also reduces the jet intensity at the valve closure and, hence, the cavitating region on the valve. Furthermore, the results show that the turbulent flow model has a better capability for prediction of cavitation duration.