Microaxial Flow Pump or Standard Care in Infarct-Related Cardiogenic Shock.

BACKGROUND: The effects of temporary mechanical circulatory support with a microaxial flow pump on mortality among patients with ST-segment elevation myocardial infarction (STEMI) complicated by cardiogenic shock remains unclear. METHODS: In an international, multicenter, randomized trial, we assigned patients with STEMI and cardiogenic shock to receive a microaxial flow pump (Impella CP) plus standard care or standard care alone. The primary end point was death from any cause at 180 days. A composite safety end point was severe bleeding, limb ischemia, hemolysis, device failure, or worsening aortic regurgitation. RESULTS: A total of 360 patients underwent randomization, of whom 355 were included in the final analysis (179 in the microaxial-flow-pump group and 176 in the standard-care group). The median age of the patients was 67 years, and 79.2% were men. Death from any cause occurred in 82 of 179 patients (45.8%) in the microaxial-flow-pump group and in 103 of 176 patients (58.5%) in the standard-care group (hazard ratio, 0.74; 95% confidence interval [CI], 0.55 to 0.99; P = 0.04). A composite safety end-point event occurred in 43 patients (24.0%) in the microaxial-flow-pump group and in 11 (6.2%) in the standard-care group (relative risk, 4.74; 95% CI, 2.36 to 9.55). Renal-replacement therapy was administered to 75 patients (41.9%) in the microaxial-flow-pump group and to 47 patients (26.7%) in the standard-care group (relative risk, 1.98; 95% CI, 1.27 to 3.09). CONCLUSIONS: The routine use of a microaxial flow pump with standard care in the treatment of patients with STEMI-related cardiogenic shock led to a lower risk of death from any cause at 180 days than standard care alone. The incidence of a composite of adverse events was higher with the use of the microaxial flow pump. (Funded by the Danish Heart Foundation and Abiomed; DanGer Shock ClinicalTrials.gov number, NCT01633502.).

Venoarterial extracorporeal membrane oxygenation is a viable option as a bridge to heart transplant.

OBJECTIVE: Venoarterial extracorporeal membrane oxygenation is a rescue therapy for patients in cardiogenic shock. We hypothesize that patients bridged to heart transplant with extracorporeal membrane oxygenation have decreased survival. METHODS: The United Network of Organ Sharing database was retrospectively reviewed from January 1, 1999, to March 31, 2018, for heart transplant recipients. Recipients bridged with any form of mechanical support and those without support were compared with recipients bridged with extracorporeal membrane oxygenation. The primary end point was restricted mean survival time through 16.7 years. RESULTS: Of 26,918 recipients, 15,076 required no pretransplant mechanical support (56.0%). Support patients included 9321 with left ventricular assist devices (34.6%), 53 with right ventricular assist devices (0.2%), 258 with total artificial hearts (1.0%), 686 with biventricular assist devices (2.6%), 1378 with intra-aortic balloon pumps (5.1%), and 146 who required extracorporeal membrane oxygenation (0.5%). In the first 16.7 years post-transplant, compared with recipients bridged with extracorporeal membrane oxygenation, estimated adjusted restricted mean survival time was higher in patients who required no mechanical support (16.6 months [14.0-19.4]) and patients with a left ventricular assist device (16.5 months [99% confidence interval, 13.9-19.2]), an intra-aortic balloon pump (11.2 months [8.3-14.7]), or a biventricular assist device (6.6 months [3.6-10.3]). Restricted mean survival time in patients with a right ventricular assist device or a total artificial heart was similar to patients with extracorporeal membrane oxygenation. CONCLUSIONS: Recipients bridged with extracorporeal membrane oxygenation were estimated to survive 16.6 months less than nonmechanical circulatory support recipients. Bridge to heart transplant with extracorporeal membrane oxygenation is a viable option, and these patients should be considered transplant candidates.

Matrix-Degrading Enzyme Expression and Aortic Fibrosis During Continuous-Flow Left Ventricular Mechanical Support.

BACKGROUND: The effects of nonphysiological flow generated by continuous-flow (CF) left ventricular assist devices (LVADs) on the aorta remain poorly understood. OBJECTIVES: The authors sought to quantify indexes of fibrosis and determine the molecular signature of post-CF-LVAD vascular remodeling. METHODS: Paired aortic tissue was collected at CF-LVAD implant and subsequently at transplant from 22 patients. Aortic wall morphometry and fibrillar collagen content (a measure of fibrosis) was quantified. In addition, whole-transcriptome profiling by RNA sequencing and follow-up immunohistochemistry were performed to evaluate CF-LVAD-mediated changes in aortic mRNA and protein expression. RESULTS: The mean age was 52 ± 12 years, with a mean duration of CF-LVAD of 224 ± 193 days (range 45-798 days). There was a significant increase in the thickness of the collagen-rich adventitial layer from 218 ± 110 µm pre-LVAD to 410 ± 209 µm post-LVAD (P < 0.01). Furthermore, there was an increase in intimal and medial mean fibrillar collagen intensity from 22 ± 11 a.u. pre-LVAD to 41 ± 24 a.u. post-LVAD (P < 0.0001). The magnitude of this increase in fibrosis was greater among patients with longer durations of CF-LVAD support. CF-LVAD led to profound down-regulation in expression of extracellular matrix-degrading enzymes, such as matrix metalloproteinase-19 and ADAMTS4, whereas no evidence of fibroblast activation was noted. CONCLUSIONS: There is aortic remodeling and fibrosis after CF-LVAD that correlates with the duration of support. This fibrosis is due, at least in part, to suppression of extracellular matrix-degrading enzyme expression. Further research is needed to examine the contribution of nonphysiological flow patterns on vascular function and whether modulation of pulsatility may improve vascular remodeling and long-term outcomes.

Advanced heart failure patients supported with ambulatory inotropic therapy: What defines success of therapy?

OBJECTIVE: The objective of this study was to describe the profiles and outcomes of a cohort of advanced heart failure patients on ambulatory inotropic therapy (AIT). BACKGROUND: With the growing burden of patients with end-stage heart failure, AIT is an increasingly common short or long-term option, for use as bridge to heart transplant (BTT), bridge to ventricular assist device (BTVAD), bridge to decision regarding advanced therapies (BTD) or as palliative care. AIT may be preferred by some patients and physicians to facilitate hospital discharge. However, counseling patients on risks and benefits is critically important in the modern era of defibrillators, durable mechanical support and palliative care. METHODS: We retrospectively studied a cohort of 241 patients on AIT. End points included transplant, VAD implantation, weaning of inotropes, or death. The primary outcomes were survival on AIT and ability to reach intended goal if planned as BTT or BTVAD. We also evaluated recurrent heart failure hospitalizations, incidence of ventricular arrhythmias (VT/VF) and indwelling line infections. Unintended consequences of AIT, such reaching unintended end point (e.g. VAD implantation in BTT patient) or worse than expected outcome after LVAD or HT, were recorded. RESULTS: Mean age of the cohort was 60.7 ± 13.2 years, 71% male, with Class III-IV heart failure (56% non-ischemic). Average ejection fraction was 19.4 ± 10.2%, pre-AIT cardiac index was 1.5 ± 0.4 L/min/m2 and 24% had prior ventricular arrhythmias. Overall on-AIT 1-year survival was 83%. Hospitalizations occurred in 51.9% (125) of patients a total of 174 times for worsening heart failure, line complication or ventricular arrhythmia. In the BTT cohort, only 42% were transplanted by the end of follow-up, with a 14.8% risk of death or delisting for clinical deterioration. For the patients who were transplanted, 1-year post HT survival was 96.7%. In the BTVAD cohort, 1-year survival after LVAD was 90%, but with 61.7% of patients undergoing LVAD as INTERMACS 1-2. In the palliative care cohort, only 24.5% of patients had a formal palliative care consult prior to AIT. CONCLUSIONS: AIT is a strategy to discharge advanced heart failure patients from the hospital. It may be useful as bridge to transplant or ventricular assist device, but may be limited by complications such as hospitalizations, infections, and ventricular arrhythmias. Of particular note, it appears more challenging to bridge to transplant on AIT in the new allocation system. It is important to clarify the goals of AIT therapy upfront and continue to counsel patients on risks and benefits of the therapy itself and potential unintended consequences. Formalized, multi-disciplinary care planning is essential to clearly define individualized patient, as well as programmatic goals of AIT.

Microcirculatory changes in venous leg ulcers using intermittent electrostimulation of common peroneal nerve.

OBJECTIVE: Activation of the venous muscle pumps of the leg by intermittent transdermal neuromuscular stimulation of the common peroneal nerve has been previously shown to augment venous and arterial flow in patients with leg ulcers. This study aims to establish if microcirculation in the wound bed and periwound area are augmented by the activation of a neuromuscular electrostimulation device (NMES) (Geko, Firstkind Ltd., UK). METHOD: In this self-controlled, observational study, laser speckle contrast imaging was used to map and quantify microcirculatory flow in the wound bed and periwound area of patients with venous leg ulcers (VLU). Values of flow and pulsatility in these locations were compared with the NMES device, both active and inactive. RESULTS: A total of 16 patients took part in the study. Microvascular flux increased by 27% (p=0.014) in the wound bed, and by 34% (p=0.004) in the periwound area, when the NMES device was activated. Pulsatility increased by 170% (p<0.001) in the wound bed and 173% (p<0.001) in the periwound area when the device was activated. CONCLUSION: Intermittent electrostimulation of the common peroneal nerve substantially increased both microcirculatory flux and pulsatility in the wound bed and in the periwound area of the VLUs of patients in this study. This provides a plausible mechanistic explanation for its reported efficacy in healing VLUs.

Neutrophil injury and function alterations induced by high mechanical shear stress with short exposure time.

High mechanical shear stresses (HMSS) can cause damage to blood, which manifests as morphologic changes, shortened life span, biochemical alterations, and complete rupture of blood cells and proteins, leading to the alterations of normal blood function. The aim of this study is to determine the state of neutrophil activation and function alterations caused by HMSS with short exposure time relevant to ventricular assist devices. Blood from healthy donors was exposed to three levels of HMSS (75Pa, 125Pa, and 175Pa) for a short exposure time (0.5 s) using our Couette-type blood-shearing device. Neutrophil activation (Mac-1, platelet-neutrophil aggregates) and surface expression levels of two key functional receptors (CD62L and CD162) on neutrophils were evaluated by flow cytometry. Neutrophil phagocytosis and transmigration were also examined with functional assays. Results showed that the expression of Mac-1 on neutrophils and platelet-neutrophil aggregates increased significantly while the level of CD62L expression on neutrophils decreased significantly after the exposure to HMSS. The Mac-1 expression progressively increased while the CD62L expression progressively decreased with the increased level of HMSS. The level of CD162 expression on neutrophils slightly increased after the exposure to HMSS, but the increase was not significant. The phagocytosis assay data revealed that the ability of neutrophils to phagocytose latex beads coated with fluorescently labeled rabbit IgG increased significantly with the increased level of HMSS. The transmigration ability of neutrophils slightly increased after the exposure to HMSS, but did not reach a significant level. In summary, HMSS with a short exposure time of 0.5 seconds could induce neutrophil activation, platelet-neutrophil aggregation, shedding of CD62L receptor, and increased phagocytic ability. However, the exposure to the three levels of HMSS did not cause a significant change in neutrophil transmigration capacity and shedding of CD162 receptor on neutrophils.

Predicting post-LVAD outcome: Is there a role for cognition?

BACKGROUND: Cognition has been found to influence risk of stroke and death for a variety of patient groups but this association has not been examined in heart failure (HF) patients undergoing left ventricular assist device (LVAD) implant. We aimed to study the relationship between cognition, stroke, and death in a cohort of patients who received LVAD therapy. It was hypothesized that cognitive test results obtained prior to LVAD placement would predict stroke and death after surgery. METHODS: We retrospectively identified 59 HF patients who had cognitive assessment prior to LVAD placement. Cognitive assessment included measures of attention, memory, language, and visualmotor speed and were averaged to produce one z-score variable per patient. Survival analyses, censored for transplant, evaluated predictors for stroke and death within a follow-up period of 900 days. RESULTS: For patients with stroke or death during the follow up period, the average cognitive z-score predicted post-LVAD stroke (HR = 0.513, 95% CI = 0.31-0.86, p = 0.012) and death (HR = 0.166, 95% CI = 0.06-0.47, p = 0.001). Cognitive performances were worse in the patients who suffered stroke or died. No other variable predicted stroke and death within the follow up period when the cognitive variable was in the model. CONCLUSION: Cognitive performance was predictive of post-LVAD risk of stroke and death. Results are consistent with findings from other studies in non-LVAD samples and may reflect early signs of neurologic vulnerability. Further studies are needed to clarify the relationship between cognition and LVAD outcomes in order to optimize patient selection, management, and advanced care planning.

Association between splenic volume and pulsatility index in patients with left ventricular assist devices.

The spleen serves as a blood volume reservoir for systemic volume regulation in heart failure (HF) patients. Changes are seen in spleen size in advanced HF patients after left ventricular assist device (LVAD) implantation. The pulsatility index (PI) is an indicator of native heart contractility with hemodynamic changes in patients using LVAD. We hypothesized that the splenic volume was associated with the PI, reflecting the hemodynamics in advanced HF patients with LVADs. Herein, we investigated the relationship between splenic volume and PI in these patients. Forty-four patients with advanced HF underwent implantation of HeartMate II® (Abbott, Chicago, IL, USA) as a bridge to heart transplantation at the Nagoya University Hospital between October 2013 and June 2019. The data of 27 patients (21 men, median age 46 years) were analyzed retrospectively. All patients underwent blood tests, echocardiography, right heart catheterization, and computed tomography (CT). Spleen size was measured via CT volumetry; the splenic volume (median: 190 mL) correlated with right arterial pressure (r = 0.431, p = 0.025) and pulmonary capillary wedge pressure (r = 0.384, p = 0.048). On multivariate linear regression analysis, the heart rate (ß = -0.452, p = 0.003), pump power (ß = -0.325, p = 0.023), and splenic volume (ß = 0.299, p = 0.038) were independent determinants of PI. The splenic volume was associated with PI, reflecting the cardiac preload in advanced HF patients with LVADs. Thus, spleen measurement using CT may help estimate the systemic volume status and understand the hemodynamic conditions in LVAD patients.

Bridge to heart transplantation in patients with cardiogenic shock: a 20-year experience with two different surgical strategies.

AIMS: We aimed to describe how treatment of patients in cardiogenic shock bridged to heart transplantation with mechanical circulatory support, using either biventricular assist devices (BVADs) or extracorporeal life support (ECLS), has evolved in the last 20 years in our centre. METHODS: Since 1998, 72 patients with refractory heart failure and indication for heart transplantation have received mechanical circulatory support: 40 had an ECLS system and 32 a BVAD. RESULTS: Early mortality was similar (17.5 vs. 9.4%, P = 0.25) regardless of the type of support. After a median support time of 8 (1-27) vs. 34 (0-385) days (P < 0.01), 70 vs. 65.6% (P = 0.69) of patients underwent transplantation in the two groups. Prior to transplantation, BVAD patients were more stable with lower need for mechanical ventilation (9 vs. 57%, P < 0.01) and dialysis (0 vs. 38%, P < 0.01). Thirty-day mortality after transplantation was similar (18 vs. 14%, P = 0.53). Patients with extracorporeal support had higher rates of renal (P = 0.02) and respiratory failure (P = 0.03), infections (P = 0.02), atrial fibrillation (P = 0.03) and longer ICU stay (P = 0.01). Late survival was similar, while 5-year freedom from coronary vasculopathy was higher in those with BVAD (P = 0.03). CONCLUSION: Although ECLS provides faster and simpler assistance compared with BVADs, no differences in early and medium-term outcomes in the last 20 years were observed in patients with cardiogenic shock. However, BVADs provided longer duration of support, better multiorgan recovery allowing more adequate graft selection, resulting in a lower rate of posttransplant complications.

Serially Measured Cytokines and Cytokine Receptors in Relation to Clinical Outcome in Patients With Stable Heart Failure.

In this prospective cohort study of 250 stable heart failure patients with trimonthly blood sampling, we investigated associations of 17 repeatedly measured cytokines and cytokine receptors with clinical outcome during a median follow-up of 2.2 (25th-75th percentile, 1.4-2.5) years. Sixty-six patients reached the primary end point (composite of cardiovascular mortality, heart failure hospitalization, heart transplantation, left ventricular assist device implantation). Repeatedly measured levels of 8 biomarkers correlated with clinical outcomes independent of clinical characteristics. Rates of change over time (slopes of biomarker evolutions) remained independently associated with outcome for 15 biomarkers. Thus, temporal patterns of cytokines and cytokine receptors, in particular tumour necrosis factor ligand superfamily member 13B and interleukin-1 receptor type 1, might contribute to personalized risk assessment.

A Case of TAVR Complicated by Severe Functional Mitral Regurgitation.

Mitral regurgitation (MR) is a known complication of transcatheter aortic valve replacement (TAVR). We report a case of a 90-year-old man with severe symptomatic aortic stenosis who underwent elective TAVR. The procedure was complicated by severe functional MR from left ventricular stunning and dilatation caused by hypotension throughout the procedure. An Impella CP (Abiomed, Inc, Danvers, MA) was inserted to unload the left ventricle and decrease its size with subsequent improvement in MR severity, which was sustained after Impella CP removal. In conclusion, we present the first case of successful management of post-TAVR severe functional MR with an Impella CP.

Apical aortic blood pump preclinical assessment for long­term use: durability test and stator topology to reduce wear in the bearing system

This study presents an assessment for long­term use of the apical aortic blood pump (AABP), focusing on wear reduction in the bearing system. AABP is a centrifugal left ventricle assist device initially developed for bridge to transplant application. To analyze AABP performance in long­term applications, a durability test was performed. This test indicated that wear in the lower bearing pivot causes device failure in long­term. A wear test in the bearing system was conducted to demonstrate the correlation of the load in the bearing system with wear. Results from the wear test showed a direct correlation between load and wear at the lower bearing pivot. In order to reduce load, thus reducing wear, a new stator topology has been proposed. In this topology, a radial stator would replace the axial stator previously used. Another durability test with the new stator has accounted twice the time without failure when compared with the original model.

Modeling Clot Formation of Shear-Injured Platelets in Flow by a Dissipative Particle Dynamics Method.

The regions with high non-physiological shear stresses (NPSS) are inevitable in blood-contacting medical devices (BCMDs) used for mechanically assisted circulatory support. NPSS can cause platelet activation and receptor shedding potentially resulting in the alteration of hemostatic function. In this study, we developed a dissipative particle dynamics model to characterize clot formation (platelet-collagen and inter-platelet adhesion) of NPSS-traumatized blood at a vascular injury site. A rectangular tube of 50 × 50 × 200 µm with an 8 × 8 µm collagen-coated area was modeled as a small blood vessel and perfusion with blood. Clot formation dynamics during perfusion was simulated. NPSS-traumatized blood was modeled to have more activated platelet and fewer adhesion receptors with weakened inter-platelet binding. Computational results showed that clots grew at a faster rate while the structure of the clots was less stable and collapsed more frequently for NPSS-traumatized blood compared with normal blood. The finding that NPSS-traumatized platelets could result in quicker but more easily breakable blood clots at injury sites may explain why increased risks of thrombotic and bleeding complications occurred concurrently in patients implanted with BCMDs.

How to Manage Temporary Mechanical Circulatory Support Devices in the Critical Care Setting: Translating Physiology to the Bedside.

The incidence of cardiogenic shock and the utilization of mechanical circulatory support devices are increasing in the US. In this review we discuss the pathophysiology of cardiogenic shock through basic hemodynamic and myocardial energetic principles. We also explore the commonly used platforms for temporary mechanical circulatory support, their advantages, disadvantages and practical considerations relating to implementation and management. It is through the translation of underlying physiological principles that we can attempt to maximize the clinical utility of circulatory support devices and improve outcomes in cardiogenic shock.

The Total Artificial Heart: Where Are We?

The total artificial heart (TAH) is a device that replaces the failing ventricles. There have been numerous TAHs designed over the last few decades, but the one with the largest patient experience is the SynCardia temporary TAH. The 50-mL and 70-mL sizes have been approved in the United States, Europe, and Canada as a bridge to transplantation. It is indicated in patients with severe biventricular failure or structural heart issues that preclude the use of a left ventricular assist device. The majority of the patients implanted are Interagency Registry for Mechanically Assisted Circulatory Support profile 1 or 2. The 1-year survival in experienced centers that have implanted over 10 TAHs is 73%. The risk factors for death include older age, need for preimplantation dialysis, and malnutrition. The most common causes of death are multiple organ failure, usually the result of physiologic deterioration before implantation, and neurologic dysfunction. The device allows the patient to be discharged home and managed as an outpatient. Proper patient selection, the timing of intervention, patient care, and device management are essential for a suitable outcome. In addition, the CARMAT TAH is another device that will soon be studied in a clinical trial in the United States. The BiVACOR TAH is a revolutionary design utilizing electromagnetic levitation that is expected to enter a clinical trial in the next few years.

Effects of gravity on flow rate estimations of a centrifugal blood pump using the eccentric position of a levitated impeller.

Implantable ventricular assist devices are a type of mechanical circulatory support for assisting the pumping of the heart. Accurate estimation of the flow rate through such devices is critical to ensure effective performance. A novel method for estimating the flow rate using the passively stabilized position of a magnetically levitated impeller was developed by our group. However, the performance of the method is affected by the gravity vector, which depends on the patient's posture. In this study, the effects of gravity on the flow estimation method are analyzed, and a compensation method is proposed. The magnetically levitated impeller is axially suspended and radially restricted by passive stability in a centrifugal blood pump developed by our group. The gravity effects were evaluated by analyzing the relationships between the radial position of the magnetically levitated impeller and the flow rate with respect to the gravity direction. Accurate estimation of the flow rate could not be achieved when the direction of gravity with respect to impeller was unknown. A mean absolute error of up to 4.89 L/min was obtained for flow rate measurement range of 0-5 L/min. However, analysis of the equilibrium of forces on the passively stabilized impeller indicated that the effects of gravity on the flow estimation could be compensated by performing additional measurements of the gravity direction with respect to impeller. The method for compensating the effects of gravity on the flow estimation should improve the performance of therapy with the implantable ventricular assist devices.

Frequency and Impact of Bleeding on Outcome in Patients With Cardiogenic Shock.

OBJECTIVES: This study sought to determine frequency, associated factors, and impact of bleeding in infarct-related cardiogenic shock. BACKGROUND: Early revascularization is associated with improved survival in patients with acute myocardial infarction complicated by cardiogenic shock. On the downside, invasive treatment and accompanying antithrombotic therapies are associated with an increased bleeding risk. Prospective data assessing the incidence, severity, risk factors, and prognostic implication of bleeding in patients with cardiogenic shock are scarce. METHODS: As a pre-defined subanalysis of the CULPRIT-SHOCK (PCI Strategies in Patients with Acute Myocardial Infarction and Cardiogenic Shock) randomized trial, we examined distribution of bleeding events in 684 patients with infarct-related cardiogenic shock and compared patients with any bleeding to those without. RESULTS: A total of 21.5% patients experienced at least 1 bleeding event until 30 days after randomization. The vast majority of bleeding (57%) occurred within the first 2 days of hospitalization. Patients with bleeding had prolonged catecholamine treatment and mechanical ventilation and there was a significant association with sepsis, peripheral ischemic complications, new atrial fibrillation, and ventricular fibrillation. In multivariable analysis, bleeding was associated with a significantly higher mortality (hazard ratio: 2.11; 95% confidence interval: 1.63 to 2.75; p < 0.0001). Treatment with active mechanical support by extracorporeal membrane oxygenation or Impella emerged as the major risk factor for bleeding. CONCLUSIONS: Risk of bleeding in infarct-related cardiogenic shock is high and associated with increased mortality.

Impeller (straight blade) design variations and their influence on the performance of a centrifugal blood pump.

INTRODUCTION: The miniaturization of blood pumps has become a trend due to the advantage of easier transplantation, especially for pediatric patients. In small-scale pumps, it is much easier and more cost-efficient to manufacture the impeller with straight blades compared to spiral-profile blades. METHODS: Straight-blade impeller designs with different blade angles, blade numbers, and impeller flow passage positions are evaluated using the computational fluid dynamics method. Blade angles (θ = 0°, 20°, 30°, and 40°), blade numbers (N = 5, 6, 7, and 8), and three positions of impeller flow passage (referred to as top, middle, and bottom) are selected as the studied parametric values. RESULTS: The numerical results reveal that with increasing blade angle, the pressure head and the hydraulic efficiency increase, and the average scalar shear stress and the normalized index of hemolysis decrease. The minimum radial force and axial thrust are obtained when θ equals 20°. In addition, the minimum average scalar shear stress and normalized index of hemolysis values are obtained when N = 6, and the maximum values are obtained when N = 5. Regarding the impeller flow passage position, the axial thrust and the stagnation area forming in the impeller eye are reduced as the flow passage height declines. CONCLUSION: The consideration of a blade angle can greatly improve the performance of blood pumps, although the influence of the blade number is not very easily determined. The bottom position of the impeller flow passage is the best design.

Catheter Ablation in Patients With Cardiogenic Shock and Refractory Ventricular Tachycardia.

BACKGROUND: There is paucity of data regarding radiofrequency ablation for ventricular tachycardia (VT) in patients with cardiogenic shock and concomitant VT refractory to antiarrhythmic drugs on mechanical support. METHODS: Patients undergoing VT ablation at our center were enrolled in a prospectively maintained registry and screened for the current study (2010-2017). RESULTS: All 21 consecutive patients with cardiogenic shock and concomitant refractory ventricular arrhythmia undergoing bailout ablation due to inability to wean off mechanical support were included. Median age was 61 years, 86% were men, median left ventricular ejection fraction was 20%, 81% had ischemic cardiomyopathy, and PAINESD score was 18±5. The type of mechanical support in place before the procedure was intra-aortic balloon pump in 14 patients (67%), Impella CP in 2, extracorporeal membrane oxygenation in 2, extracorporeal membrane oxygenation and intra-aortic balloon pump in 2, and extracorporeal membrane oxygenation and Impella CP in 1. Endocardial voltage maps showed myocardial scar in 19 patients (90%). The clinical VTs were inducible in 13 patients (62%), whereas 6 patients had premature ventricular contraction-induced ventricular fibrillation/VT (29%), and VT could not be induced in 2 patients (9%). Activation mapping was possible in all 13 with inducible clinical VTs. Substrate modification was performed in 15 patients with scar (79%). After ablation and scar modification, the arrhythmia was noninducible in 19 patients (91%). Seventeen (81%) were eventually weaned off mechanical support successfully, but 6 (29%) died during the index admission from persistent cardiogenic shock. Patients who had ventricular arrhythmia and cardiogenic shock on presentation had a trend toward lower in-hospital mortality compared with those who presented with cardiogenic shock and later developed ventricular arrhythmia. CONCLUSIONS: Bailout ablation for refractory ventricular arrhythmia in cardiogenic shock allowed successful weaning from mechanical support in a large proportion of patients. Mortality remains high, but the majority of patients were discharged home and survived beyond 1 year.