Changing Strategy Between Bridge to Transplant and Destination LVAD Therapy After the First 3 Months: Analysis of the STS-INTERMACS Database.

BACKGROUND: Left ventricular assist devices (LVADs) have been implanted as bridge to transplantation (BTT), bridge to candidacy (BTC) or destination therapy (DT) on the basis of relative and absolute contraindications to transplantation. Multiple factors may lead to changes in the strategy of support after LVAD implantation. METHODS: Based on INTERMACS (Interagency Registry for Mechanically Assisted Circulatory Support) 2012-2020 data, 11,262 patients survived to 3 months on continuous-flow LVADs with intent of BTT or DT. Preimplant characteristics and early events post-LVAD were analyzed in relation to changes in BTT or DT strategy during the next 12 months. RESULTS: Among 3216 BTT patients at 3 months, later transplant delisting or death without transplant occurred in 536 (16.7%) and was more common with age, profiles 1-2, renal dysfunction, and independently for prior cardiac surgery (HR 1.25, 95% CI 1.04-1.51; P = 0.02). Post-LVAD events of infections, gastrointestinal bleeding, stroke, and right heart failure as defined by inotropic therapy, predicted delisting and death, as did in-hospital location at 3 months (HR 1.67, 95% CI 1.20-2.33; P = 0.0024). Of 8046 patients surviving to 3 months with the intent of destination therapy, 750 (9.3%) subsequently underwent listing or transplantation, often with initial histories of acute HF (HR 1.70, 95% CI 1.27-2.27; P = 0.0012) or malnutrition-cachexia (1.73, 95% CI 1.14-2.63; P = 0.0099). Multiple gastrointestinal bleeding events (≥ 4) with LVAD increased transition from BTT to DT (HR 4.22, 95% CI 1.46-12.275; P = 0.0078) but also from DT to BTT (HR 5.17, 95% CI 1.92-13.9; P = 0.0011). CONCLUSIONS: Implant strategies change over time in relation to preimplant characteristics and adverse events post implant. Preimplant recognition of factors predicting later change in implant strategy will refine initial triage, whereas further reduction of post-LVAD complications will expand options, including eventual consideration of heart transplantation.

Computational investigation of outflow graft variation impact on hemocompatibility profile in LVADs.

BACKGROUND: Hemocompatibility-related adverse events (HRAE) occur commonly in patients with left ventricular assist devices (LVADs) and add to morbidity and mortality. It is unclear whether the outflow graft orientation can impact flow conditions leading to HRAE. This study presents a simulation-based approach using exact patient anatomy from medical images to investigate the influence of outflow cannula orientation in modulating flow conditions leading to HRAEs. METHODS: A 3D model of a proximal aorta and outflow graft was reconstructed from a computed tomography (CT) scan of an LVAD patient and virtually modified to model multiple cannula orientations (n = 10) by varying polar (cranio-caudal) (n = 5) and off-set (anterior-posterior) (n = 2) angles. Time-dependent computational flow simulations were then performed for each anatomical orientation. Qualitative and quantitative hemodynamics metrics of thrombogenicity including time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), endothelial cell platelet activation potential (ECAP), particle residence time (PRT), and platelet activation potential (PLAP) were analyzed. RESULTS: Within the simulations performed, endothelial cell activation potential (ECAP) and particle residence time (PRT) were found to be lowest with a polar angle of 85°, regardless of offset angle. However, polar angles that produced parameters at levels least associated with thrombosis varied when the offset angle was changed from 0° to 12°. For offset angles of 0° and 12° respectively, flow shear was lowest at 65° and 75°, time averaged wall shear stress (TAWSS) was highest at 85° and 35°, and platelet activation potential (PLAP) was lowest at 65° and 45°. CONCLUSION: This study suggests that computational fluid dynamic modeling based on patient-specific anatomy can be a powerful analytical tool when identifying optimal positioning of an LVAD. Contrary to previous work, our findings suggest that there may be an "ideal" outflow cannula for each individual patient based on a CFD-based hemocompatibility profile.

Depressive symptoms, right ventricular function, and muscular strength are associated with peak oxygen uptake in patients with implantable left ventricular assist devices.

BACKGROUND: Left ventricular assist device (LVAD) implantation is among the most effective treatment options for patients with severe heart failure. Although previous studies have examined the factors related to peak oxygen uptake (peak VO2 ), they were limited by the few patients involved and their focus on medical and physical functions. Therefore, this study comprehensively examined the factors associated with peak VO2 , which is an important prognostic factor in patients with implantable LVADs. METHODS: Eighty-nine patients who underwent initial LVAD implantation and were eligible for cardiopulmonary exercise testing (CPX) between May 2014 and September 2021 were included. The patients' mean age was 48 ± 12 years, and 70% were males. Based on previous studies, the cut-off was set at 12 and 14 mL/kg/min for patients taking ß-blocker and those not taking ß-blockers, respectively. Furthermore, factors associated with peak VO2 were examined using multivariate logistic regression analysis. RESULTS: The mean time from surgery to CPX administration was 73 ± 40 days. The high group had a higher cardiac index, right ventricular stroke work index (RVSWI), and isometric knee extensor muscular strength and lower Patient Health Questionnaire-9 (PHQ-9) and B-type natriuretic peptide values than the low group. Multivariate logistic regression analysis showed that RVSWI and KEMS were positively correlated, whereas PHQ-9 was negatively associated with peak VO2 . CONCLUSION: Right ventricular function, depressive symptoms, and lower limb muscular strength were associated with exercise capacity in patients with implantable LVADs.

Preliminary report of extracorporeal blood purification therapy in patients receiving LVAD: Cytosorb or Jafron HA330.

BACKGROUND: Left ventricular assist device (LVAD) candidates are at increased risk of immune dysregulation and infectious complications. To attenuate the elevated proinflammatory cytokine levels and associated adverse clinical outcomes, it has been postulated that extracorporeal blood purification could improve the overall survival rate and morbidity of patients undergoing LVAD implantation. METHODS: We retrospectively reviewed prospectively collected data of 15 patients who underwent LVAD implantation at our center between January 2021 and March 2022. Of these, 15 (100%) who received HeartMate 3™ (St. Jude Medical, Abbott, MN, USA) device were eligible. Intraoperatively, patients were single randomized 1:1:1 to three groups: group 1, patients who received Cytosorb therapy (n = 5; installed in the CPB circuit); group 2, patients who received Jafron HA330 (n = 5; installed in the CPB circuit); and control group 3, patients who did not receive filter (n = 5; usual care, neither Cytosorb nor Jafron during CPB). Baseline patient characteristics and intraoperative data were compared between the groups. Blood sample analyses were performed to assess the levels of inflammatory markers (IL-1, 6, 8; CRP, Leukocyte, Lactate, PCT, NT-proBNP, TNF-α) in both preoperative and postoperative data. RESULTS: Baseline patient characteristics were similar in all three groups. We found that IL1α; IL 6; IL8; Lactatedehydrogenase, PCT, pro-BNP, CRP; Leukocyte, and TNFα levels significantly increased with LVAD implantation and that neither Cytosorb nor Jafron influenced this response. In-hospital mortality and overall survival during follow-up were similar among the groups. CONCLUSION: Our preliminary results showed that hemoadsorption therapy using Cytosorb or Jafron hemoadsorption (HA) 330 may not be clinically beneficial for patients with advanced heart failure undergoing LVAD implantation. Large prospective studies are needed to evaluate the potential role of HA therapy in improving outcomes in patients undergoing LVAD implantation.

Advancements in left ventricular assist devices to prevent pump thrombosis and blood coagulopathy.

Mechanical circulatory support (MCS) devices, such as left ventricular assist devices (LVADs) are very useful in improving outcomes in patients with advanced-stage heart failure. Despite recent advances in LVAD development, pump thrombosis is one of the most severe adverse events caused by LVADs. The contact of blood with artificial materials of LVAD pumps and cannulas triggers the coagulation cascade. Heat spots, for example, produced by mechanical bearings are often subjected to thrombus build-up when low-flow situations impair washout and thus the necessary cooling does not happen. The formation of thrombus in an LVAD may compromise its function, causing a drop in flow and pumping power leading to failure of the LVAD, if left unattended. If a clot becomes dislodged and circulates in the bloodstream, it may disturb the flow or occlude the blood vessels in vital organs and cause internal damage that could be fatal, for example, ischemic stroke. That is why patients with LVADs are on anti-coagulant medication. However, the anti-coagulants can cause a set of issues for the patient-an example of gastrointestinal (GI) bleeding is given in illustration. On account of this, these devices are only used as a last resort in clinical practice. It is, therefore, necessary to develop devices with better mechanics of blood flow, performance and hemocompatibility. This paper discusses the development of LVADs through landmark clinical trials in detail and describes the evolution of device design to reduce the risk of pump thrombosis and achieve better hemocompatibility. Whilst driveline infection, right heart failure and arrhythmias have been recognised as LVAD-related complications, this paper focuses on complications related to pump thrombosis, especially blood coagulopathy in detail and potential strategies to mitigate this complication. Furthermore, it also discusses the LVAD implantation techniques and their anatomical challenges.

Gastrointestinal bleeding in recipients of left ventricular assist devices-a systematic review.

The twenty-first century has revolutionized the management of congestive heart failure with the widespread use of left ventricular assist devices and other treatment modalities that improve morbidity and mortality after the failure of medical management. These novel devices come with significant side effects. One of the most common side effects of left ventricular assist devices is the increased frequency of lower gastrointestinal bleeding compared to heart failure patients without left ventricular assist devices. Multiple etiologies of recurrent gastrointestinal bleeding in such patients have been studied. The decreased amount of von Willebrand factor polymers is now recognized as one of the most common causes of increased incidence of gastrointestinal bleeding in patients with left ventricular assist devices alongside increased arteriovenous malformations. Multiple treatment modalities have been identified to prevent and treat gastrointestinal bleeding in these patients. Since the use of left ventricular assist devices is becoming more prevalent in patients with advanced heart failure, we decided to conduct this systematic review. The article summarizes the incidence, pathophysiology, and management of lower gastrointestinal bleeding in patients with left ventricular assist devices.

Gastrointestinal bleeding in patients with continuous-flow left ventricular assist devices: A comprehensive review.

BACKGROUND: Gastrointestinal bleeding is a major cause of morbidity that plagues the quality of life of patients supported on contemporary continuous-flow left ventricular assist devices (CF-LVADs). Despite benefits in survival and the nearly 50% reduction in complications provided by CF-LVADs, bleeding remains one of the most frequent adverse events with CF-LVAD implants. The CF-LVADs cause an increased risk of bleeding mainly due to the activation of the coagulation cascade. METHODS: A literature search was done using PubMed and Google Scholar from Inception to February 2022. Qualitative analyses of the articles retrieved were used to construct this review. This review attempts to provide a comprehensive summary of the epidemiology, pathophysiology, risk stratification, and management of gastrointestinal bleeding as a complication of CF-LVAD as well as propose an algorithm for diagnosis and treatment. RESULTS: Bleeding can occur at different sites in the gastrointestinal tract, the most common underlying pathology being arteriovenous malformations located in the upper gastrointestinal tract The increased prevalence of gastrointestinal (GI) bleeding in CF-LVAD patients has been attributed to the physiology of the LVAD itself, the use of anticoagulants, as well as patient comorbidities. Management involves pharmacologic and nonpharmacologic strategies. CONCLUSIONS: CF-LVAD-supported patients have a significant risk of GI bleeding that is mainly caused by arteriovenous malformations located in the upper GI tract. The increased prevalence of GI bleeding in CF-LVAD patients is attributed to several etiologies that include factors attributed to the device itself and extrinsic factors such as the use of anticoagulation.

Impella 5.5 support before, during, and after surgical ventricular septal defect repair: A bridge continuum.

INTRODUCTION: Post-infarction ventricular septal defect formation remains a formidable mechanical complication of acute myocardial infarction associated with increased morbidity and mortality. CASE PRESENTATION: We describe the case of a 72-year-old male who was admitted with post-myocardial infarction ventricular septal defect and cardiogenic shock. DISCUSSION: Impella 5.5 with SmartAssist as temporary left ventricular assist device provided sufficient support throughout multiple bridging episodes including failed percutaneous repair and subsequent definitive surgical repair. Contemporary management of post-infarction ventricular septal defect is discussed.

Reduction of Adverse Events With Phosphodiesterase 5 Inhibitors Post LVAD Implantation: Is It Time for a Randomized Trial?

The improved survival of patients with advanced heart failure after left ventricular assist device (LVAD) implantation together with the scarcity of donor hearts has significantly increased the population of LVAD-supported patients. However, despite the improvement in LVAD technology and the advent of third-generation continuous flow LVADs, complications such as those related to hemocompatibility and stroke rates remain ongoing clinical challenges. Thus, improvement in LVAD technology should be coupled with innovative medical management to further reduce adverse events. We have previously shown a strong association between post LVAD implant phosphodiesterase-5 inhibitors (PDE-5i) use and fewer thrombotic events, as well as improved survival in 2 observational studies. We caution, nevertheless, the use of PDE-5i based on these observations and encourage clinicians to support enrollment in a randomized control trial. A randomized control trial will determine the efficacy and safety of PDE-5i use after implantation in patients with a centrifugal flow LVAD.

Systems of conductive skin for power transfer in clinical applications.

The primary aim of this article is to review the clinical challenges related to the supply of power in implanted left ventricular assist devices (LVADs) by means of transcutaneous drivelines. In effect of that, we present the preventive measures and post-operative protocols that are regularly employed to address the leading problem of driveline infections. Due to the lack of reliable wireless solutions for power transfer in LVADs, the development of new driveline configurations remains at the forefront of different strategies that aim to power LVADs in a less destructive manner. To this end, skin damage and breach formation around transcutaneous LVAD drivelines represent key challenges before improving the current standard of care. For this reason, we assess recent strategies on the surface functionalization of LVAD drivelines, which aim to limit the incidence of driveline infection by directing the responses of the skin tissue. Moreover, we propose a class of power transfer systems that could leverage the ability of skin tissue to effectively heal short diameter wounds. In this direction, we employed a novel method to generate thin conductive wires of controllable surface topography with the potential to minimize skin disruption and eliminate the problem of driveline infections. Our initial results suggest the viability of the small diameter wires for the investigation of new power transfer systems for LVADs. Overall, this review uniquely compiles a diverse number of topics with the aim to instigate new research ventures on the design of power transfer systems for IMDs, and specifically LVADs.

Impact of narrowing perioperative antibiotic prophylaxis for left ventricular assist device implantation.

BACKGROUND: Although infections are a significant potential complication among patients undergoing left ventricular assist device (LVAD) implantation, standardized surgical infection prophylaxis (SIP) regimens are not well defined. At Montefiore Medical Center, a 4-drug SIP regimen containing fluconazole, ciprofloxacin, rifampin, and vancomycin was previously utilized. In January 2020, the antimicrobial stewardship program implemented a 2-drug SIP regimen of vancomycin and cefazolin to limit exposure to broad-spectrum antibiotics. This study evaluated LVAD-associated infection rates prior to and following the SIP revision. METHODS: A retrospective review of patients who underwent LVAD implantation from 1/2018 to 4/2021 was performed. Infections were classified using the International Society for Heart and Lung Transplantation definitions. Infection rates at 2 weeks, 30 days, and 90 days post-implantation in the 4-drug SIP regimen (1/2018-12/2019) and the 2-drug SIP regimen (1/2020 to 4/2021) were compared. RESULTS: A total of 71 patients were included. The number of patients with LVAD-associated infections (including surgical site infections) was not significantly different in either SIP group at 2 weeks (9% vs. 4%, p = .64), 30 days (9% vs. 11%, p = .99), or 90 days (19% vs. 14%, p = .75). There was no statistically significant difference in 30 or 90-day mortality. LVAD-associated gram-negative (7% vs. 7%; p > .99) and fungal (5% vs. 0%; p = .51) infections were uncommon. The most common organism isolated was Staphylococcus aureus, and the most common type of infection was pneumonia in both SIP groups. CONCLUSION: No significant difference in LVAD-associated infections or infection-related mortality was observed with de-escalation of perioperative antibiotics. Additional studies with larger sample sizes are needed to endorse the findings of this study.

Outcomes in patients with smaller body surface area after HeartMate 3 left ventricular assist device implantation.

BACKGROUND: Due to anatomic and physiologic concerns, prior generations of the left ventricular assist devices (LVAD) have frequently been denied to patients with small body size. However, outcomes in patients with small body surface area (BSA) following HeartMate 3 (HM3) LVAD implantation remain relatively unknown. METHODS: A cohort of 220 patients implanted at a single center was divided into two groups: BSA ≤1.8 m2 (small BSA, n = 37) and BSA >1.8 m2 (large BSA, n = 183). We investigated baseline characteristics and clinical outcomes including survival and incidence of adverse events. RESULTS: Small BSA patients were older (60 vs. 57 years), more likely female (60% vs. 20%), had a lower body mass index (24 vs. 32 kg/m2 ), lower incidence of diabetes (32% vs. 51%), history of stroke (5% vs. 19%), and left ventricular thrombus (0% vs. 11%). They had smaller left ventricular end diastolic diameter (64.8 vs. 69.3 mm). Pump speed and pump flows at discharge were lower in the small BSA group. Survival at 1 year and 2 years was 86% versus 87% and 86% versus 79% for small versus large BSA groups (p = 0.408), respectively. The rates of adverse events were similar between groups and there were no cases of confirmed pump thrombosis. The incidence of readmissions for low flow alarms was higher in the small BSA group (0.55 vs. 0.24 EPPY). CONCLUSIONS: These findings demonstrate comparable outcomes in patients with small body size and suggest that this parameter should not be an exclusion criterion on patients who are otherwise candidates for HM3 LVAD implantation.

Clinical characteristics and outcomes of patients with ventricular arrhythmias after continuous-flow left ventricular assist device implant.

BACKGROUND: Ventricular arrhythmias (VAs) are observed in 25%-50% of continuous-flow left ventricular assist device (CF-LVAD) recipients, but their role on mortality is debated. METHODS: Sixty-nine consecutive patients with a CF-LVAD were retrospectively analyzed. Study endpoints were death and occurrence of first episode of VAs post CF-LVAD implantation. Early VAs were defined as VAs in the first month after CF-LVAD implantation. RESULTS: During a median follow-up of 29.0 months, 19 patients (27.5%) died and 18 patients (26.1%) experienced VAs. Three patients experienced early VAs, and one of them died. Patients with cardiac resynchronization therapy (CRT-D) showed a trend toward more VAs (p = 0.076), compared to patients without CRT-D; no significant difference in mortality was found between patients with and without CRT-D (p = 0.63). Patients with biventricular (BiV) pacing ≥98% experienced more frequently VAs (p = 0.046), with no difference in mortality (p = 0.56), compared to patients experiencing BiV pacing <98%. There was no difference in mortality among patients with or without VAs after CF-LVAD [5 patients (27.8%) vs. 14 patients (27.5%), p = 0.18)], and patients with or without previous history of VAs (p = 0.95). Also, there was no difference in mortality among patients with a different timing of implant of implantable cardioverter-defibrillator (ICD), before and after CF-LVAD (p = 0.11). CONCLUSIONS: VAs in CF-LVAD are a common clinical problem, but they do not impact mortality. Timing of ICD implantation does not have a significant impact on patients' survival. Patients with BiV pacing ≥98% experienced more frequently VAs.

Missing the blind spot in a HeartMate 3 LVAD outflow graft obstruction caused by fungal infection.

A patient was admitted in cardiogenic shock and a constant decrease of pump flow requiring combined inotropic support. To evaluate the cause, echocardiography and a ramp test were performed. The results suggested a LVAD related problem - particularly a suspected outflow graft obstruction. Wether CT scan nor angiography confirmed the assumption. However, a post-mortem LVAD examination revealed an outflow obstruction caused by a fungal thrombus formation invisible for standard imaging procedures.

Acquired platelet defects are responsible for nonsurgical bleeding in left ventricular assist device recipients.

BACKGROUND: Left ventricular assist devices (LVADs) have been used as a standard treatment option for patients with advanced heart failure. However, these devices are prone to adverse events. Nonsurgical bleeding (NSB) is the most common complication in patients with continuous flow (CF) LVADs. The development of acquired von Willebrand syndrome (AVWS) in CF-LVAD recipients is thought to be a key factor. However, AVWS is seen across a majority of LVAD patients, not just those with NSB. The purpose of this study was to examine the link between acquired platelet defects and NSB in CF-LVAD patients. METHODS: Blood samples were collected from 62 CF-LVAD patients at pre- and 4 post-implantation timepoints. Reduced adhesion receptor expression (GPIbα and GPVI) and activation of platelets (GPIIb/IIIa activation) were used as markers for acquired platelet defects. RESULTS: Twenty-three patients experienced at least one NSB episode. Significantly higher levels of platelet activation and receptor reduction were seen in the postimplantation blood samples from bleeders compared with non-bleeders. All patients experienced the loss of high molecular weight monomers (HMWM) of von Willebrand Factor (vWF), but no difference was seen between the two groups. Multivariable logistic regression showed that biomarkers for reduced platelet receptor expression (GPIbα and GPVI) and activation (GPIIb/IIIa) have more predictive power for NSB, with the area under curve (AUC) values of 0.72, 0.68, and 0.62, respectively, than the loss of HMWM of vWF (AUC: 0.57). CONCLUSION: The data from this study indicated that the severity of acquired platelet defects has a direct link to NSB in CF-LVAD recipients.

What is known in pre-, peri-, and post-procedural anticoagulation in micro-axial flow pump protected percutaneous coronary intervention?

Interest in the use of percutaneous left ventricular assist devices (p-LVADs) for patients undergoing high-risk percutaneous coronary intervention (PCI) is growing rapidly. The Impella™ (Abiomed Inc.) is a catheter-based continuous micro-axial flow pump that preserves haemodynamic support during high-risk PCI. Anticoagulation is required to counteract the activation of the coagulation system by the patient's procoagulant state and the foreign-body surface of the pump. Excessive anticoagulation and the effect of dual antiplatelet therapy (DAPT) increase the risk of bleeding. Inadequate anticoagulation leads to thrombus formation and device dysfunction. The precarious balance between bleeding and thrombosis in patients with p-LVAD support is often the primary reason that patients' outcomes are jeopardized. In this chapter, we will discuss anticoagulation strategies and anticoagulant management in the setting of protected PCI. This includes anticoagulant therapy with unfractionated heparin, direct thrombin inhibitors, DAPT, purge blockage prevention by bicarbonate-based purge solution, and monitoring by activated clotting time, partial thromboplastin time, as well as anti-factor Xa levels. Here, we provide a standardized approach to the management of peri-interventional anticoagulation in patients undergoing protected PCI.

[Mechanical circulatory support systems : When and how much protection does a PCI need?] / Mechanische Kreislaufunterstützungssysteme : Wie viel Schutz braucht eine PCI wann?

The interventional treatment of high-risk patients remains challenging and has a high potential for improvement despite all technical innovations. Mechanical circulatory support (MCS) systems can be meaningful depending on the clinical situation, although a clear study situation for this is so far lacking. Multivessel coronary disease and a high SYNTAX score combined with impaired ventricular function is a possible predictor combination for the use of MCS that justifies the higher risk of complications.

Transcutaneous Pulsed RF Energy Transfer Mitigates Tissue Heating in High Power Demand Implanted Device Applications: In Vivo and In Silico Models Results.

This article presents the development of a power loss emulation (PLE) system device to study and find ways of mitigating skin tissue heating effects in transcutaneous energy transmission systems (TETS) for existing and next generation left ventricular assist devices (LVADs). Skin thermal profile measurements were made using the PLE system prototype and also separately with a TETS in a porcine model. Subsequent data analysis and separate computer modelling studies permit understanding of the contribution of tissue blood perfusion towards cooling of the subcutaneous tissue around the electromagnetic coupling area. A 2-channel PLE system prototype and a 2-channel TETS prototype were implemented for this study. The heating effects resulting from power transmission inefficiency were investigated under varying conditions of power delivery levels for an implanted device. In the part of the study using the PLE setup, the implanted heating element was placed subcutaneously 6-8 mm below the body surface of in vivo porcine model skin. Two operating modes of transmission coupling power losses were emulated: (a) conventional continuous transmission, and (b) using our proposed pulsed transmission waveform protocols. Experimental skin tissue thermal profiles were studied for various levels of LVAD power. The heating coefficient was estimated from the porcine model measurements (an in vivo living model and a euthanised cadaver model without blood circulation at the end of the experiment). An in silico model to support data interpretation provided reliable experimental and numerical methods for effective wireless transdermal LVAD energization advanced solutions. In the separate second part of the study conducted with a separate set of pigs, a two-channel inductively coupled RF driving system implemented wireless power transfer (WPT) to a resistive LVAD model (50 Ω) to explore continuous versus pulsed RF transmission modes. The RF-transmission pulse duration ranged from 30 ms to 480 ms, and the idle time (no-transmission) from 5 s to 120 s. The results revealed that blood perfusion plays an important cooling role in reducing thermal tissue damage from TETS applications. In addition, the results analysis of the in vivo, cadaver (R1Sp2) model, and in silico studies confirmed that the tissue heating effect was significantly lower in the living model versus the cadaver model due to the presence of blood perfusion cooling effects.

Radiographic risk factors for intracranial hemorrhage in patients with left ventricular assist devices.

OBJECTIVE: Intracranial hemorrhage (ICH) in patients with left ventricular assist devices (LVAD) is a devastating complication. Demographic risk factors for ICH in LVAD patients are defined, however anatomic predispositions to ICH are unknown. We sought to interrogate intracranial radiographic risk factors for ICH in LVAD patients. METHODS: We reviewed 440 patients who received an LVAD from 2008-2021. We selected patients with CT scans of the head either before or after LVAD placement, but typically within 5 years. 288 patients (21 ICH, 267 Control) with imaging were included. A detailed chart review was performed on demographics, radiographic features, and management. RESULTS: The incidence of ICH in our total cohort was 8.6% (38/440). The presence of pump thrombosis (p=0.001), driveline infection (p=0.034), other hemorrhage (p=0.001), or previous placement of a cardio-defibrillator (p=.003) was associated with increased risk for ICH. An analysis of imaging revealed that the presence of a mass (p=0.006), vascular pathology (p=0.001), and microangiopathy (p=0.04) was significantly associated with ICH in LVAD patients. These radiographic features were validated with a multivariate logistic regression which confirmed presence of a mass (aOR 332.1, 95% CI: 14.7-7485.1, p<0.001), vascular pathology (aOR 69.7, 95% CI: 1.8-2658.8, p=0.022), and microangiopathy (aOR 6.5, 95% CI: 1.1-37.6, p=0.035) were independently associated with ICH. CONCLUSION: Radiographic evidence of microangiopathy, intracranial mass, and vascular pathology are independent risk factors for ICH which are readily identified by imaging. We advocate that CT imaging be used to further stratify patients at highest risk of ICH during treatment with an LVAD.

Ventricular fibrillation in a left ventricular assist device patient: Can the echocardiogram be misleading?

Sustained ventricular tachycardia and ventricular fibrillation (VF) are life-threatening arrhythmias which remain highly prevalent in patients with advanced heart failure. These ventricular arrhythmias may impair the support provided by continuous-flow left ventricular assist devices (CF-LVADs) and lead to frequent hospitalizations, antiarrhythmic medication use, external defibrillations, and need for heart transplantation. We report a case in which a patient with a CF-LVAD and an implantable cardioverter defibrillator at end of life presented with asymptomatic low-flow alarms and was found to have VF of unknown duration. Unique in our case was the presence of apparent organized contractility and rhythmic opening of the mitral valve on echocardiogram despite VF on electrocardiogram.