Microaxial Blood Pump Research Articles

Mechanical circulatory support for cardiogenic shock during the peripartum period.

Cardiomyopathies account for more than half of the cardiovascular disease during the peripartum period. In the extreme, patients may present with cardiogenic shock (CS) requiring mechanical circulatory support (MCS). The aim of this study was to report our experience with CS requiring MCS in the peripartum period. We present a single-center retrospective analysis of all CS cases involving MCS during the peripartum period that occurred between 2012 and 2023. Eleven cases were included. Median age was 33, median BMI was 30.4, and 73% underwent a caesarian-section for delivery. CS presentation occurred in 36.4% during pregnancy and in 63.6% after delivery. Most patients were in Society for Cardiovascular Angiography & Interventions (SCAI) Stage C shock and in 37% the suspected etiology was peripartum cardiomyopathy. MCS usage included intra-aortic balloon pump (4), Impella microaxial blood pump (2), veno-arterial extracorporeal membrane oxygenation (6), and temporary right ventricle assist devices (2), with some patients having multiple MCS devices. The rate of major complications was 36.4%. During a median follow-up of 4.5 years, 7 patients had sustained cardiac recovery (63.6%), 1 patient (9.1%) underwent cardiac transplantation, 2 patients (18.2%) received a durable LVAD, and 2 (18.2%) have died. MCS in severe CS cases during the peripartum period is rare and associated with favorable outcomes. High recovery rates suggest favoring first MCS/LVAD over transplant.

Impact of Impeller Speed Adjustment Interval on Hemolysis Performance of an Intravascular Micro-Axial Blood Pump.

In recent years, intravascular micro-axial blood pumps have been increasingly used in the treatment of patients with cardiogenic shock. The flow rate of such blood pumps requires adjustment based on the patient's physiological condition. Compared to a stable flow state with fixed rotation speed, adjusting the speed of blood pump impeller to alter flow rate may lead to additional hemolysis. This study aimed at elucidating the relationship between adjusting interval of a blood pump's impeller speed and the hemolysis index. By comparing simulation results with P-Q characteristic curves of the blood pump measured by experiments, the accuracy of the blood pump flow field simulation model was confirmed. In this study, a drainage tube was employed as the device analogous to an intravascular micro-axial blood pump for achieving similar shear stress levels and residence times. The hemolysis finite element prediction method based on a power-law model was validated through hemolysis testing of porcine blood flow through the drainage tube. The validated models were subsequently utilized to investigate the impact of impeller speed adjusting intervals on hemolysis in the blood pump. Compared to steady flow, the results demonstrate that the hemolysis index increased to 6.3% when changing the blood pump flow rate from 2 L/min to 2.5 L/min by adjusting the impeller speed within 0.072 s. An adjustment time of impeller speed longer than 0.072 s can avoid extra hemolysis when adjusting the intravascular micro-axial blood pump flow rate from 2 L/min to 2.5 L/min.

Percutaneous intravascular micro-axial blood pump: current state and perspective from engineering view.

The utilization of a minimally invasively placed catheter-mounted intravascular micro-axial flow blood pump (IMFBP) is increasing in the population with advanced heart failure. The current development of IMFBPs dates back around the 1990s, namely the Hemopump with a wire-drive system and the Valvopump with a direct-drive system. The wire-drive IMFBPs can use a brushless motor in an external console unit to transmit rotational force through the drive wire rotating the impeller inside the body. The direct-drive IMFBPs require an ultra-miniature and high-power brushless motor. Additionally, the direct-drive system necessitates a mechanism to protect against blood immersion into the motor. Therefore, the direct-drive IMFBPs can be categorized into two types of devices: those with seal mechanisms or those with sealless mechanisms using magnetically coupling. The IMFBPs can be classified into two groups depending on their purpose. One group is for cardiogenic shock following a heart attack or for use in high-risk percutaneous coronary intervention (PCI), and the other group serves the purpose of acute decompensated heart failure. Both direct-drive IMFBPs and wire-drive IMFBPs have their own advantages and disadvantages, and efforts are being made to develop and improve, and clinically implement them, leveraging their own strengths. In addition, there is a possibility that innovative new devices may be invented. For researchers in the field of artificial heart development, IMFBPs offer a new area of research and development, providing a novel treatment option for severe heart failure.

An in silico analysis of unsteady flow structures in a microaxial blood pump under a pulsating rotation speed

Background and objectiveVentricular assist devices (VADs) are generally designed to perform continuous flow. However, it has been proven that continuous flow, which is not a physiological hemodynamic state, may cause severe complications such as gastrointestinal bleeding, pulmonary hypertension, and ventricular suction. For these reasons, many pulsating blood pump control strategies have been proposed and have the potential for application in percutaneous ventricular assist devices (pVADs) or microaxial blood pumps. A few cases report extra hemolysis when introducing pulsating speed, while none involve blood pumps. This research's primary purpose is to evaluate the potential hemolysis of pVAD under pulsating flow conditions. MethodsFirst, the pulsating flow state is deduced using a heart failure model and varying speed. The heart model is established according to the pathology state collected from a clinical check. The rotation speed and boundary physical state are set to fit the heart failure model. The computational fluid dynamics (CFD) method with the hemolysis prediction model is performed. Furthermore, we used proper orthogonal decomposition (POD) analysis to reconstruct the flow field and obtain more details about shearing and transporting effects. Results(1) As a variable rotational speed was introduced, no significant gain in hemolysis accumulation appeared in pVAD. This is quite different from long-term implantable VADs. (2) Pulsation affects hemolysis mainly through pressure (or normal stress). Variable rotational speed affects hemolysis mainly through flow instability. (3) Variable rotational speed will increase the instability and influence hemolysis by transporting and shearing effects, while the transporting effect is more significant. ConclusionsThe unsteady flow state will affect the spatial distribution of hemolysis, which should be taken into account during control strategy and impeller shape design.

Cell-scale hemolysis evaluation of intervenient ventricular assist device based on dissipative particle dynamics.

Most of the existing hemolysis mechanism studies are carried out on the macro flow scale. They assume that the erythrocyte membranes with different loads will suffer the same damage, which obviously has limitations. Thus, exploring the hemolysis mechanism through the macroscopic flow field information is a tough challenge. In order to further understand the non-physiological shear hemolysis phenomenon at the cell scale, this study used the coarse-grained erythrocytes damage model at the mesoscopic scale based on the transport dissipative particle dynamics (tDPD) method. Combined with computational fluid dynamics the hemolysis of scalarized shear stress () in the clearance of "Impella 5.0" was evaluated under the Lagrange perspective and Euler perspective. The results from the Lagrange perspective showed that the change rate of scaled shear stress () was the most critical factor in damaging RBCs in the rotor region of "Impella 5.0"and other transvalvular micro-axial blood pumps. Then, we propose a dimensionless number with time integration based on to evaluate hemolysis. The Dissipative particle dynamics simulation results are consistent with the evaluation results, so may be an important factor in the hemolysis of VADs. Finally, we tested the hemolysis of 30% hematocrit whole blood in the "Impella 5.0" shroud clearance from the Euler perspective. Relevant results indicate that because of the wall effect, the RBCs near the impeller side are more prone to damage, and most of the cytoplasm is also gathered at the rotor side.

The design and evaluation of the outflow structures of an interventional microaxial blood pump.

Blood pump design efforts are focused on enhancing hydraulic effectiveness and minimizing shear stress. Unlike conventional blood pumps, interventional microaxial blood pumps have a unique outflow structure due to minimally invasive technology. The outflow structure, composed of the diffuser and cage bridges, is crucial in minimizing the pump size to provide adequate hemodynamic support. This study proposed four outflow structures of an interventional microaxial blood pump depending on whether the diffuser with or without blades and cage bridges were straight or curved. The outflow flow structure's effect on the blood pump's hydraulic performance and shear stress distribution was evaluated by computational fluid dynamics and hydraulic experiments. The results showed that all four outflow structures could achieve the pressure and flow requirements specified at the design point but with significant differences in shear stress distribution. Among them, the outflow structure with curved bridges would make the blood dispersed more evenly when flowing out of the pump, which could effectively reduce the shear stress at the cage bridges. The outflow structure with blades would aggravate the secondary flow at the leading edge of the impeller, increasing the risk of flow stagnation. The combination of curved bridges and the bladeless diffuser had a relatively better shear stress distribution, with the proportion of fluid exposed to low scalar shear stress (<50Pa) and high scalar shear stress (>150Pa) in the blood pump being 97.92% and 0.26%, respectively. It could be concluded that the outflow structure with curved bridges and bladeless diffuser exhibited relatively better shear stress distribution and a lower hemolysis index of 0.00648%, which could support continued research on optimizing the microaxial blood pumps.

Sodium bicarbonate alters protein stability and blood coagulability in a simulated Impella purge gap model.

The Impella® microaxial blood pumps utilize purge fluid containing heparin to prevent biofouling of internal surfaces. Purge fluid interfaces with blood or blood components at two notable internal locations: (1) 5-8μm radial gap ("Radial Gap" or "Gap 1") between the motor shaft and bearing, a site accessible by blood proteins or small molecules; and (2) 100 μm axial gap ("Axial Gap" or "Gap 2") between the impeller rotor and bearing, the site of mixing with larger circulating blood components. Despite its efficacy, heparin in the purge fluid complicates overall patient anticoagulation management. Here, we investigate sodium bicarbonate as an alternative to heparin in the purge fluid in a simulated purge gap micro-environment. To assess protein stability simulated at Gap 1, human serum albumin (HSA; 40 mg/ml) species were quantified utilizing size exclusion liquid chromatography (SEC-HPLC) after stirring with purge fluid (5% dextrose in water (D5W) with heparin (25 U/ml) or sodium bicarbonate (25 or 50 mEq/L)) over a 24-h period. pH measurements were taken immediately prior to stirring. Mixing between blood and purge fluid at Gap 2 was mimicked in vitro utilizing a 60:40 blood: purge fluid ratio. Purge fluid consisted of D5W with or without sodium bicarbonate (25 or 50 mEq/L). Human citrated blood samples were freshly collected with or without the addition of heparin (5U/ml). Coagulability was determined via thromboelastography (TEG). pH measurements of blood mixtures were taken immediately before and after TEG analysis. Sodium bicarbonate alone or synergistically with heparin was effective in increasing protein stability, increasing pH, and reducing coagulability. In the Gap 1 model, sodium bicarbonate led to preservation of HSA monomer after 24h mixing, with monomer composing 88.3 ± 2.3% and 88.6 ± 0.9% of total HSA species for 25 or 50 mEq/L sodium bicarbonate, respectively. Only 60.4 ± 4.3% monomer was observed with D5W alone (p < 0.005). HSA aggregates and fragments were evident in heparin and D5W purge mixtures, but absent in sodium bicarbonate (25 and 50 mEq/L). pH of HSA mixtures significantly increased in the presence of sodium bicarbonate. In the Gap 2 model, combined heparin (5U/ml) and sodium bicarbonate prolonged clotting time (TEG-ACT), leading to an average increase of 795 ± 275 s (p=0.04) and 846 243 s (p=0.03). This trend of reduced coagulability was similarly observed in clot initiation time (R time), clot formation time (K time), and clotting rate (α angle). Blood mixture pH measurements increased with addition of sodium bicarbonate in both heparinized and non-heparinized blood samples. Sodium bicarbonate in the purge fluid has the potential to significantly increase protein stability and reduce protein denaturation at the Impella® radial gap (Gap 1), while reducing blood coagulation at the Impella® axial gap (Gap 2). The influence of sodium bicarbonate on the biochemical environment of the purge fluid may ensure stable purge flow resistance and play a synergistic or supportive role in the purge gap micro-environment when used with systemic anticoagulation.

1121 USE OF IMPELLA 5.0 AS BRIDGE TO LVAD IN CARDIOGENIC SHOCK: REPORT OF TWO CASES

Abstract Background Left ventricle assist devices (LVAD) are an option in end stage heart failure (HF) as bridge to or alterative to heart transplantation. Adequate compensation of patient is key to obtain a good outcome. We report two cases of Impella 5.0 bridge to LVAD in patients with cardiogenic shock (CS) in which intra-aortic balloon pump (IABP) failed to obtain hemodynamic stability. Case series A) A 60 years old man developed CS after anterior myocardial infarction treated with primary PCI of left main coronary artery. At presentation patient was hypotensive with signs of hypoperfusion and pulmonary congestion: systemic blood pressure (SBP) 80/60 mmHg despite inotropic drugs, blood lactates 4 mmol/l, urine output of last 6 hours 0,4 ml/kg/h (INTERMACS 2). Echocardiography showed severe left ventricle disfunction with LVEF 15%, severe mitral regurgitation (MR) and sPAP 45 mmHg. Therefore, IABP was implanted. Right heart catheterization (RHC) showed pulmonary hypertension and high filling pressure with reduced cardiac output and increased pulmonary vascular resistance (mPAP 39 mmHg, CPWP 28 mmHg, CO 3 l/min, PVR 3.7 uW, PAPi 2.8); X-ray chest showed persistence of pulmonary congestion. After 9 days on IABP, patient underwent Impella 5.0 implant through right axillary artery as bridge to durable LVAD. Pulmonary artery catheter (PAC) monitoring showed reduction of pulmonary hypertension with mPAP 35 mmHg and CPWP 17 mmHg and chest X-ray documented improvement of lung congestion. Bedside rehabilitation was started. Two weeks later patient underwent LVAD HM3 implantation as destination therapy. The patient was discharge home on post-operative day 55. B) After subacute myocardial infarction with three-vessels disease, a 53 y.o. man developed severe congestive HF with severe left ventricular disfunction and was referred to our institution for evaluation. RHC showed pulmonary hypertension with pre-capillary component not reversible after enoximone test, contraindicating heart transplantation. Therefore, patient was candidate to receive LVAD as bridge strategy. Echocardiography at admission showed dilated and hypokinetic left ventricle (EDV 200 ml, LVEF 17% severe MR, sPAP 60 mmHg) and dilated and hypokinetic RV. During hospitalization the patient experienced CS with SBP 62/45 mmHg, 6-hours urine output of 1,4 ml/kg/h and blood lactates 8.3 mmol/l (INTERMACS 1) so femoral IABP was implanted. RHC was repeated both without IABP support (mPAP 37 mmHg, PCWP 28 mmHg, CO 1.4 l/min, CI 0.9 l/min/m2) and with IABP support (mPAP 32 mmHg, PCWP 18 mmHg, CO 2.15 l/min, CI 1.4 l/min/m2). During the following stay he developed S. Aureus sepsis requiring prolonged antibiotic therapy. Expecting a long time before LVAD, axillary Impella 5.0 was implanted in order to unload the LV and allow early patient mobilization. Subsequent PAC monitoring showed improvement of pulmonary hypertension and cardiac index (mPAP 24 mmHg, PCWP 9 mmHg, CO 5.1 l/min with Impella flow 4.2 l/min, CI 3.2 l/min/m2). After 11 days, patient received LVAD HVAD with uneventful course and was discharged on post-operative day 22. Conclusions Impella 5.0 is a surgically implanted intravascular microaxial blood pump that delivers up to 5 l/min of blood from LV to aorta, leading to improved perfusion and more efficient LV unloading. In patients with CS this can help to obtain better decongestion, RV recovery, and favorable preconditioning before LVAD implant. Moreover, axillary access allows better patient mobilization preventing cachexia after long time hospitalization.

A Review of the Impella Devices.

The use of mechanical circulatory support (MCS) to provide acute haemodynamic support for cardiogenic shock or to support high-risk percutaneous coronary intervention (HRPCI) has grown over the past decade. There is currently no consensus on best practice regarding its use in these two distinct indications. Impella heart pumps (Abiomed) are intravascular microaxial blood pumps that provide temporary MCS during HRPCI or in the treatment of cardiogenic shock. The authors outline technical specifications of the individual Impella heart pumps and their accompanying technology, the Automated Impella Controller and SmartAssist, their indications for use and patient selection, implantation techniques, device weaning and escalation, closure strategies, anticoagulation regimens, complications, future directions and upcoming trials.

POSC233 Frequency of Use of Percutaneous Mechanical Circulatory Support in Germany: IABP, MBP & VA-ECMO During 2006 - 2018

The aim of this study was to evaluate the frequency and distribution of different mechanical circulatory support (pMCS) systems in Germany:•Intraaortic Balloon Pump (IABP)•Microaxial blood pumps (MBP)•Veno-arterial Extracorporeal membrane oxygenation (va-ECMO) The analysis is based on coding data from hospital quality reports by the Federal Joint commission and the Federal Statistical Office. Only procedures with final-digit procedure numbers were counted. Essentially, this is a secondary use of data from various primary sources, some of which have been calculated in-house. Following a strong increase in numbers in the first two years, the annual increase for all pMCS is 16% between 2008 and 2018. While initially >90% of all pMCS were attributed to IABP, in 2018 it was only about one in five. This change occurred primarily in favor of va-ECMO, which accounted for 50% of all procedures in 2018. While the number of performing centers rose steep from 252 to 415 in the beginning, it stabilized at about 350 clinics nationwide by 2018. During the study period, the highest number of IABP was recorded in 2009 with 10,777 services. Since then, the number has declined to only 2,436 interventions in 2018, a decrease of -69.3% compared to 2006. The largest decline in IABP procedures occurred from 2012 (n = 8,677) to 2013, at -30% (n = 6,038). Explanations for this could be the changed evidence situation on this technique due to the ISAR-SHOCK II study, but also the expansion of other, alternative procedures such as MBP and ECMO. The latter in particular recorded a 224% increase over the same period, from 986 services in 2012 to 3,192 services in 2013.

Impella use in real-world cardiogenic shock patients: Sobering outcomes

BackgroundCritically ill patients with cardiogenic shock could benefit from ventricular assist device support using the Impella microaxial blood pump. However, recent studies suggested Impella not to improve outcomes. We, therefore, evaluated outcomes and predictors in a real-world scenario.MethodsIn this retrospective single-center trial, 125 patients suffering from cardiac arrest/cardiogenic shock between 2008 and 2018 were analyzed. 93 Patients had a prior successful cardiopulmonary resuscitation. The primary endpoint was hospital mortality. Associations of covariates with the primary endpoint were assessed by univariable and multivariable logistic regression. Adjusted odds ratios (aOR) and optimal cut-offs (using Youden index) were obtained.ResultsHospital mortality was high (81%). Baseline lactate was 4.7mmol/L [IQR = 7.1mmol/L]. In multivariable logistic regression, only age (aOR 1.13 95%CI 1.06–1.20; p<0.001) and lactate (aOR 1.23 95%CI 1.004–1.516; p = 0.046) were associated with hospital mortality, and the respective optimal cut-offs were >3.3mmol/L and age >66 years.Patients were retrospectively stratified into three risk groups: Patients aged ≤66 years and lactate ≤3.3mmol (low-risk; n = 22); patients aged >66 years or lactate >3.3mmol/L (medium-risk; n = 52); and patients both aged >66 years and lactate >3.3mmol/L (high-risk, n = 51). Risk of death increased from 41% in the low-risk group, to 79% in the medium risk group and 100% in the high-risk group. The predictive abilities of this model were high (AUC 0.84; 95% 0.77–0.92).ConclusionMortality was high in this real-world collective of severely ill cardiogenic shock patients. Better patient selection is warranted to avoid unethical use of Impella. Age and lactate might help to improve patient selection.

ECMELLA 2.0: Single Arterial Access Technique for a Staged Approach in Cardiogenic Shock

The main drawbacks of venoarterial extracorporeal life support (VA-ECLS) for cardiogenic shock are incomplete left ventricular unloading with concomitant pulmonary edema and vascular access site complications. We describe the staged treatment technique for severe cardiogenic shock with a combination of the Impella 5.0/5.5 (Abiomed Inc, Danvers, MA) and peripheral ECLS (ECMELLA) using a single arterial access in 2 consecutive patients with refinement of the technique in the second case. The arterial cannula was inserted through the same vascular graft in the axillary artery that served as access for the previously implanted microaxial blood pump.

The hemodynamic effect of different left ventricular unloading techniques during veno-arterial extracorporeal life support: a systematic review and meta-analysis.

Pulmonary edema and left ventricular thrombosis may arise during veno-arterial extracorporeal life support due to an increase in cardiac load. This mechanical stress can be reduced through different left ventricular unloading techniques. We set out to quantitatively summarize the hemodynamic effects of available methods in patients treated with veno-arterial extracorporeal life support. Literature was systematically searched for studies reporting left ventricular unloading during veno-arterial extracorporeal life support as reflected by changes in left atrial pressure, pulmonary capillary wedge pressure, diastolic pulmonary artery pressure, or left ventricular end-diastolic pressure. For studies including ⩾10 patients per group, changes in these parameters were pooled using (1) standardized mean differences and (2) ratio of means. Assessment of potential bias was performed for all studies. Eight studies met the inclusion criteria. Reported techniques included use of intra-aortic balloon pump (n = 1), micro-axial blood pump (Impella®, n = 2), left ventricular venting (n = 1), and atrial septostomy (n = 4). Overall, left ventricular unloading was associated with a statistically significant reduction in preload parameters (standardized mean differences = -1.05 (95% confidence interval = -1.24 to -0.86) and ratio of means = 0.60 (0.47 to 0.76)). Effect sizes were strongest for micro-axial blood pump and atrial septostomy (standardized mean differences = -1.11 (-1.55 to -0.68) and -1.22 (-1.47 to -0.96), and ratio of means = 0.58 (0.39 to 0.86) and 0.54 (0.36 to 0.83), respectively). Left ventricular unloading was associated with a significant reduction in left ventricular preload parameters in the setting of veno-arterial extracorporeal life support. This effect may be most pronounced for micro-axial blood pump and atrial septostomy.

P2626Outcome of patients in cardiogenic shock supported with a micro-axial blood pump providing 5 l/min blood flow

Abstract Introduction Percutaneous mechanical circulatory support devices are increasingly used in acute cardiogenic shock (CS), despite limited evidence for their effectiveness. The aim of this study was to evaluate outcomes associated with use of the full support Impella 5 and 5.5 as a short- term left ventricular device (LVAD) and to identify preoperative predictors of short -term mortality. Methods Data of patients in CS (n=51) treated with the Impella 5 (n=48) and 5.5 (n=3) devices at our institution were collected retrospectively. The primary endpoint was 30-day all-cause mortality. Clinical follow up including adverse events was analyzed. Results Mean age was 58.2±12.1 years; 80.4% were male. 13 patients had BMI &gt;30 kg/m2. CS was caused by acute myocardial infarction (n=14), decompensated chronic heart failure (n=29), postcardiotomy syndrom and acute myocarditis (n=4 each). Before implantation, median Intermacs profile was 1 (range 1–3) and 31 patients (61%) were on respiratory support. In 49 patients the axillary artery was used for vascular access (n=4 left and n=45 right) employing a 10mm dacron graft tunneled through the skin, in one patient left femoral artery and ascending aorta, respectively. Median support time was 14 days. In 12 cases the pump was removed for myocardial recovery. In 15 patients a continuous flow permanent LVAD was implanted. Bleeding (n=9), thromboembolic event (n=5), pump dislodgement (n=7) requiring revision occurred during support. Seven patients developed ventricular arrhythmia requiring flow reduction. In 5 cases the pump was explanted for hemolysis, in 2 other patients pump exchange was performed. The overall 30-day survival was 53% (95% CI: 38.8–67.1%). Penalized multivariable logistic regression analysis identified preoperative elevated lactate (p=0.027) and CK-MB (p=0.022) as predictors for 30- day mortality. On the basis of these data, a nomogram to estimate 30d-mortality after Impella implantation was created. Conclusion Stabilization of patients suffering from CS employing temporary full support Impella LVAD is feasible and results in acceptable survival. Preoperative degree of shock and myocardial damage predict the short-term mortality. Effect of full support Impella LVAD in earlier stages of shock may prevent irreversible end organ damage.

CRT-45 Use Of Impella® In Complex High Risk Percutaneous Coronary Intervention

IMPELLA® is a new vascular micro-axial blood pump with a flow of 2.5 L/min. It allows the unloading of the left ventricle. 11 consecutive male patients (mean age 65±7 years), with coronary artery disease (9 with three vessels disease, 2 with left main stenosis and two coronary vessels disease, 5

Successful bridge to recovery using a microaxial blood pump in a patient with electrical storm and cardiogenic shock

A 59-year-old patient with dilated cardiomyopathy and incessant ventricular tachycardia leading to progressive cardiogenic shock is presented. Due to hemodynamic instability, high dose catecholamines were required in addition to the implantation of an intraaortic balloon pump (IABP), which, however, appeared to further augment the frequency and duration of ventricular tachycardias. The implantation of a microaxial blood pump allowed catecholamine administration to be terminated, thereby, ending this vicious circle of catecholamine-driven electrical storm. Within 5days, the patient was hemodynamically stabilized and kidney and liver function recovered with the support of intensive antiarrhythmic therapy (amiodarone, mexiletine, sotalol). During a 24-month follow-up, the patient had no further ICD shocks and no rehospitalization was required for treatment of congestive heart failure.

Successful bridge to recovery using a microaxial blood pump in a patient with electrical storm and cardiogenic shock

Successful bridge to recovery using a microaxial blood pump in a patient with electrical storm and cardiogenic shock

Particle Tracking Computational Prediction of Hemolysis by Blade of Micro-Axial Blood Pump

By analyzing fluid dynamics of blood in an artificial blood pump and simulating the flow field structure and the flow performance of blood, the blood flow and the damages in the designed blood pump would be better understood. This paper describes computational fluid dynamic (CFD) used in predicting numerically the hemolysis of blade in micro-axial blood pumps. A numerical hydrodynamical model, based on the Navier-Stokes equation, was used to obtain the flow in a micro-axial blood pump. A time-dependent stress acting on blood particle is solved in this paper to explore the blood flow and damages in the micro-axial blood pump. An initial attempt is also made to predict the blood damage from these simulations.

Abdominal aortic aneurysm surgery with mechanical support using the Impella(R) microaxial blood pump

A 50-year-old man with an end-stage cardiac failure was referred to our institution for pre-transplantation assessment. An infrarenal aortic aneurysm (diameter 45 mm) was discovered and progressed (up to 59 mm) over a two-month period. Decision to perform aneurysmectomy with the support of an Impella Recover LP50 microaxial blood pump was decided regarding the rapid evolution of the disease. The patient had uneventful cardiac-wise during surgery and postoperative period.

Emboli Formation Rather Than Inflammatory Mediators Are Responsible for Increased Cerebral Water Content After Conventional and Assisted Beating-Heart Myocardial Revascularization in a Porcine Model

Emboli and proinflammatory mediators are suspected of generating cerebral edema after coronary surgery. In contrast to cardiopulmonary bypass (CPB), off-pump coronary artery bypass surgery (OPCAB) reduces microemboli count and proinflammatory mediator release but carries the risk of hemodynamic instability. A microaxial blood pump can augment cardiac output. Coronary bypasses were constructed in pigs with CPB and cardioplegia (n=9), OPCAB (n=9), or blood-pump support CAB (n=9). Nine animals underwent sham operation. Embolus count was monitored and regional cerebral blood flow was assessed with microspheres in 21 brain specimens per animal (n=189 per group). Interleukins 6 and 8 and tumor necrosis factor-alpha concentrations were determined. These variables were studied before, during, and for 4 hours after surgery. Finally, cerebral water content was determined. During CPB and blood-pump CAB, a significant number of emboli were counted in contrast to OPCAB and controls (P<0.05). During CPB, regional cerebral blood flow was affected (32 of 189) and showed reactive hyperemia except in 10 specimens after aortic cross-clamp release. This impairment persisted in 20 specimens. During and after OPCAB, regional cerebral blood flow remained nearly unchanged but showed low flow during (58 of 189) and after (35 of 189) the blood-pump run. A significant increase in proinflammatory mediators was observed only in the CPB group. CPB and blood-pump CAB significantly increased cerebral water content (P<0.05). A strong correlation between embolic load and cerebral water content was observed in all groups. No correlation between proinflammatory mediator release and cerebral water content was detected. Emboli formation rather than inflammatory mediators are responsible for increased cerebral water content after conventional and assisted beating-heart myocardial revascularization.