Fulminant Myocarditis and Venoarterial Extracorporeal Membrane Oxygenation: A Systematic Review.

This systematic review aimed to look at the effectiveness of venoarterial extracorporeal membrane oxygenation (VA-ECMO) therapy in treating fulminant myocarditis and evaluating the optimal length of time a patient should be placed on VA-ECMO. Fulminant myocarditis is a potentially life-threatening medical condition most commonly brought on by cardiogenic shock, which often progresses to severe circulatory compromise, requiring the patient to be placed on some form of mechanical circulatory assistance to maintain adequate tissue perfusion. Medical centers have multiple mechanical assistive devices available for treatment at their disposal, but our area of focus was placed on one system in particular: VA-ECMO therapy. Although the technology has been around for more than 30 years, there is limited information on how effective VA-ECMO is regarding the treatment of fulminant myocarditis. Due to the lack of data regarding the treatment administration of VA-ECMO for fulminant myocarditis, standard treatment duration guidelines do not exist, resulting in a wide variation of treatment administrations among medical centers. In regard to short-term outcomes, VA-ECMO has shown to be effective in treating fulminant myocarditis, with a one-year post-hospital survival rate ranging from 57.1% to 78% at discharge. For long-term health and survival, the studies that recorded long-term survival ranged from 65% to 94.1%. However, given the small number of studies that pursue this, more research is needed to prove the efficacy of VA-ECMO for the treatment of fulminant myocarditis.

Long-term predictors of morbidity and mortality in patients following LVAD replacement.

BACKGROUND: As heart transplant guidelines evolve, the clinical indication for 73% of durable left ventricular assist device (LVAD) implants is now destination therapy. Although completely magnetically levitated LVAD devices have demonstrated improved durability relative to previous models, LVAD replacement procedures are still required for a variety of indications. Thus, the population of patients with a replaced LVAD is growing. There is a paucity of data regarding the outcomes and risk factors for those patients receiving first-time LVAD replacements. METHODS: The study cohort consisted of all consecutive patients between 2006 and 2020 that received a first-time LVAD replacement at a single institution. Preoperative clinical and laboratory variables were collected retrospectively. The primary endpoint was death or need for an additional LVAD replacement. Data were subjected to Kaplan-Meier, univariate, and multivariate Cox hazard ratio analyses. RESULTS: In total, 152 patients were included in the study, of which 101 experienced the primary endpoint. On multivariate analysis, patients receiving HeartMate 3 (HM3) LVADs as the replacement device showed superior outcomes (HR 0.15, 95% CI 0.065-0.35, p < 0.0001). Independent risk factors for death or need for additional replacement included preoperative extracorporeal membrane oxygenation (ECMO) (HR 4.44, 95% CI 1.87-14.45, and p = 0.00042), increased number of sternotomies (HR 5.20, 95% CI 1.87-14.45, and p = 0.0016), and preoperative mechanical ventilation (HR 1.98, 95% CI 1.01-3.86, and p = 0.045). CONCLUSIONS: Replacement with HM3 showed superior outcomes compared to all other pump types when controlling for both initial pump type and other independent predictors of death or LVAD replacement. Preoperative ECMO, mechanical ventilation, and multiple sternotomies also increased the odds for death or the need for subsequent replacement.

Design and optimisation of an Intra-Aortic Shrouded rotor axial pump.

Undesirable side effects in patients with a LVAD (Left Ventricular Assist Device) pump fitted include blood damage, thrombosis, blood traumatisation, and End-Organ Disfunctions. These side effects have generally been attributed to the high wall shear stresses and the induced turbulent flow. In this study, we introduce a novel design to address these effects by lowering the rotational speed and providing an optimum flow path design to minimise blood damage. We present an initial scheme for a new Intra-Aortic Shrouded Rotary Axial Pump and develop a sequence of pump geometries, for which the Taguchi Design Optimisation Method has been applied. We apply CFD tools to simulate the pressure rise, pump performance, hydraulic efficiency, wall shear stress, exposure time and mass flow rate. A prototype pump has been tested in a mock cardiovascular circuit using a water-glycerol solution. The optimum design delivered the desired pressure/mass flow rate characteristics at a significantly low rpm (2900 rpm). As a result, the estimated blood damage index is low, matching the design requirements. The theoretical performance was matched by experimental results.

Technology landscape of pediatric mechanical circulatory support devices: A systematic review 2010-2021.

BACKGROUND: Mechanical circulatory support (MCS) devices, such as ventricular assist devices (VADs) and total artificial hearts (TAHs), have become a vital therapeutic option in the treatment of end-stage heart failure for adult patients. Such therapeutic options continue to be limited for pediatric patients. Clinicians initially adapted or scaled existing adult devices for pediatric patients; however, these adult devices are not designed to support the anatomical structure and varying flow capacities required for this population and are generally operated "off-design," which risks complications such as hemolysis and thrombosis. Devices designed specifically for the pediatric population which seek to address these shortcomings are now emerging and gaining FDA approval. METHODS: To analyze the competitive landscape of pediatric MCS devices, we conducted a systematic literature review. Approximately 27 devices were studied in detail: 8 were established or previously approved designs, and 19 were under development (11 VADs, 5 Fontan assist devices, and 3 TAHs). RESULTS: Despite significant progress, there is still no pediatric pump technology that satisfies the unique and distinct design constraints and requirements to support pediatric patients, including the wide range of patient sizes, increased cardiovascular demand with growth, and anatomic and physiologic heterogeneity of congenital heart disease. CONCLUSIONS: Forward-thinking design solutions are required to overcome these challenges and to ensure the translation of new therapeutic MCS devices for pediatric patients.

Progression of aortic valve insufficiency during centrifugal versus axial flow left ventricular assist device support.

OBJECTIVES: Long-term left ventricular assist device (LVAD) support can cause accelerated progression of aortic insufficiency (AI). The MOMENTUM trial has led to increased use of the HeartMate 3 (HM3) LVAD, due to greater hemocompatibility. However, the differential effect on the rate of progression of AI during HM3 support versus HeartMate 2 (HM2) has not been extensively studied. This analysis compares the rates of progression to moderate or severe AI (MSAI) comparing a cohort of patients supported with the HM2 versus HM3. METHODS: A retrospective review was performed on all consecutive patients implanted with HM2 or HM3 between May 2005 and June 2020. Follow-up time was limited to the first 6 years after LVAD implantation. Demographics and 4005 echocardiograms were assessed for 536 HM2 and 300 HM3 patients. The primary end point was progression to MSAI. Univariable and multivariable Cox proportional hazard regression and landmark analyses were performed. RESULTS: Progression to MSAI was greater in the HM2 (17%) versus HM3 (9.9%) cohort. On the univariable analysis, the hazard ratio for HM3 was 0.581 (95% confidence interval 0.370-0.909, P = 0.02) whereas on multivariable analysis hazard ratio was 0.624 (95% confidence interval 0.386-1.008, P = 0.0537). Preoperative AI, female sex and body surface area <2 were significantly associated with progression to MSAI. Landmark analysis suggests that LVAD type has the most significant effect on progression to MSAI between 1 and 2 years post-implantation. CONCLUSIONS: Current practice strategies achieved low rates of progression to MSAI. Preoperative AI, female sex and body surface area <2 were the most important predictors of progression to MSAI. Pump type appears to be of secondary importance.

Integrated long-term multifunctional pediatric mechanical circulatory assist device.

There continues to be limited, viable ventricular assist device technology options to support the dysfunctional states of pediatric heart failure. To address this need, we are developing a magnetically suspended, versatile pumping technology that uniquely integrates two blood pumps in a series configuration within a single device housing. This device enables operational switching from the usage of one pump to another as needed for clinical management or to support growth and development of the pediatric patient. Here, we present the initial design where we conducted a virtual fit study, the Taguchi Design Optimization Method, iterative design to develop pump geometries. Computational tools were used to estimate the pressure generation, capacity delivery, hydraulic efficiency, fluid stress levels, exposure time to stresses, blood damage index, and fluid forces on the impellers. Prototypes of the pumps were tested in a flow loop using a water-glycerin solution. Both designs demonstrated the capability to generate target pressures and flows. Blood damage estimations were below threshold levels and achieved design requirements; however, maximum scalar stress levels were above the target limit. Radial and axial forces were less than 1 N and 10 N, respectively. The performance data trends for physical prototypes correlated with theoretical expectations. The centrifugal prototype was able to generate slightly higher pressure rises than numerical predictions. In contrast, the axial prototype outperformed the computational studies. Experimental data were both repeatable and reproducible. The findings from this research are promising, and development will continue.

Minimally Invasive Mechanical Circulatory Support Through the Perioperative Pulmonary Thromboendarterectomy Period: A Case Report.

A 64-year-old man being evaluated for pulmonary thromboendarterectomy (PTE) preoperatively experienced pulseless electrical activity secondary to right ventricular failure while undergoing bronchoscopy. After return of spontaneous circulation, a percutaneous right ventricular assist device (RVAD) was placed through the right internal jugular vein. He continued on right ventricular support with demonstration of right ventricular recovery over the following 8 days, and subsequently underwent PTE for treatment of his primary condition. He recovered and was weaned from his RVAD support uneventfully. The need for RVAD support has traditionally been a contraindication for PTE; however, circulatory assist devices have been used as a salvage procedure for right-heart failure after PTE. This case highlights the potential for percutaneous mechanical circulatory support in treating severe perioperative right ventricular dysfunction, and to facilitate successful recovery in patients undergoing PTE.

Right Heart Failure After Left Ventricular Assist Device Placement: Medical and Surgical Management Considerations.

Durable left ventricular assist device therapy is an increasingly accepted surgical therapy for advanced heart failure refractory to guideline-directed medical therapy. Right heart failure is a known and frequent complication after durable left ventricular assist device implantation and remains an important clinical challenge. Medical management of right heart failure after left ventricular assist device therapy focuses on improving right ventricular contractility and optimizing right ventricular preload and afterload. Mechanical circulatory support options include surgical and percutaneous devices options as well as the total artificial heart or heart transplantation. Early institution of therapy is necessary to reduce the morbidity and mortality.

Successful Use of Intra-aortic Balloon Counterpulsation for Systemic Ventricular Failure Following Total Pericardiectomy for Calcific Chronic Constrictive Pericarditis.

We report two male patients aged 18 and 19 years, respectively, undergoing total pericardiectomy for chronic calcific constrictive pericarditis who developed systemic ventricular failure unresponsive to medical management following surgery. The failing circulation was successfully reestablished using intra-aortic balloon counterpulsation. Aortic counterpulsation facilitates recovery of ventricular function and appears to be a reasonable alternative in select instances of refractory cardiac failure following pericardiectomy.

New versatile dual-support pediatric heart pump.

Mechanical circulatory support (MCS) devices for pediatric patients continue to lag in development behind those for adults. There is no heart pump with the design innovation to support dysfunctional states of heart failure and the anatomic heterogeneity of cardiac defects in pediatric patients. To address this unmet need, we are developing a versatile MCS technology with 2 separate blood pumps under 1 housing, whereby a centrifugal pump rotates around an axial pump. In this study, we advanced the design with a new inducer for the axial pump component and flat inlet volute for the centrifugal pump component. We conducted computational modeling of the design iterations, built prototypes, and tested their performance. The axial pump component was able to generate pressure rises of 1-112 mm Hg for 2-5 L/min at 10 000-14 000 RPM, and the centrifugal pump component produced pressure rises of 1-184 mm Hg for 2-5 L/min at 1750-3000 RPM. Shear stresses and blood damage estimations were less than  490 Pa and 0.5%, respectively. Axial and radial forces were also estimated to be less than 5 N for the axially and radially centered impellers. Data sets were repeatable, and data trends followed theoretical expectations. The new designs for the axial and centrifugal pumps enabled us to reduce the height of the pump while maintaining performance expectations. These findings support the continued development of this new medical device for pediatric patients.

Hybrid Continuous-Flow Total Artificial Heart.

Clinical studies using total artificial hearts (TAHs) have demonstrated that pediatric and adult patients derive quality-of-life benefits from this form of therapy. Two clinically-approved TAHs and other pumps under development, however, have design challenges and limitations, including thromboembolic events, neurologic impairment, infection risk due to large size and percutaneous drivelines, and lack of ambulation, to name a few. To address these limitations, we are developing a hybrid-design, continuous-flow, implantable or extracorporeal, magnetically-levitated TAH for pediatric and adult patients with heart failure. This TAH has only two moving parts: an axial impeller for the pulmonary circulation and a centrifugal impeller for the systemic circulation. This device will utilize the latest generation of magnetic bearing technology. Initial geometries were established using pump design equations, and computational modeling provided insight into pump performance. The designs were the basis for prototype manufacturing and hydraulic testing. The study results demonstrate that the TAH is capable of delivering target blood flow rates of 1-6.5 L/min with pressure rises of 1-92 mm Hg for the pulmonary circulation and 24-150 mm Hg for the systemic circulation at 1500-10 000 rpm. This initial design of the TAH was successful and serves as the foundation to continue its development as a novel, more compact, nonthrombogenic, and effective therapeutic alternative for infants, children, adolescents, and adults with heart failure.

Transplantation in a patient on extracorporeal membrane oxygenation with infective endocarditis, pericarditis and heparin-induced thrombocytopenia.

Heart failure patients with pacemaker or defibrillator-associated endocarditis in cardiogenic shock have few treatment options. We present a case of an INTERMACS I patient who developed device infection, sepsis, bacterial pericarditis and heparin-induced thrombocytopenia. The patient was stabilized with extracorporeal membrane oxygenation and successfully transplanted.

A multi-institutional outcome analysis of patients undergoing left ventricular assist device implantation stratified by sex and race.

BACKGROUND: Earlier studies have demonstrated disparities in patients undergoing left ventricular assist device (LVAD) implantation when stratified according to sex and race. Because very few data exist from large investigations, we reviewed data from the registry of the Mechanical Circulatory Support Research Network. METHODS: Between May 2004 and September 2014, 734 patients underwent primary LVAD implantation at our institutions. Median age at implant was 57 (range 18 to 82) years and there were 577 males (80%). Race included Caucasian (C) in 586 patients (82%), African-American (AA) in 112 (16%), and other (O) in 21 (3%). Between sexes, significant pre-operative differences most commonly included median age at implant (males 60 years, females 57 years), ischemic etiology (53% vs 35%) and mean INTERMACS profile (2.9 vs 2.5). Between races, significant pre-operative differences most commonly included median age at implant (C = 61 vs AA = 51 vs O = 51), New York Heart Association functional class (85% vs 100% vs 92%) and ischemic etiology (55% vs 24% vs 40%). RESULTS: There were no significant differences in survival at 1, 3 or 5 years by sex or race. Similarly, there were no differences in time-related freedom from stroke, drive-line infection, gastrointestinal bleeding or pump thrombus by sex or race. After controlling for differences, neither sex nor race was associated with survival (p = 0.09 and p = 0.18, respectively), stroke (p = 0.28 and p = 0.21), drive-line infection (p = 0.9 and p = 0.92), gastrointestinal bleed (p = 0.48 and p = 0.45) or pump thrombus (p = 0.99 and p = 0.8). CONCLUSIONS: In this large, multi-institutional analysis, although some pre-operative clinical characteristics varied, they did not translate into any significant differences in late survival or complications while on LVAD support.

Minimally Invasive Implantation of HeartWare Assist Device and Simultaneous Tricuspid Valve Reconstruction Through Partial Upper Sternotomy.

Left ventricular assist device (LVAD) implantation is a well-established therapy to support patients with end-stage heart failure. However, the operative procedure is associated with severe trauma. Third generation LVADs like the HeartWare assist device (HeartWare, Inc., Framingham, MA, USA) are characterized by enhanced technology despite smaller size. These devices offer new minimally invasive surgical options. Tricuspid regurgitation requiring valve repair is frequent in patients with the need for mechanical circulatory support as it is strongly associated with ischemic and nonischemic cardiomyopathy. We report on HeartWare LVAD implantation and simultaneous tricuspid valve reconstruction through minimally invasive access by partial upper sternotomy to the fifth left intercostal space. Four male patients (mean age 51.72 ± 11.95 years) suffering from chronic heart failure due to dilative (three patients) and ischemic (one patient) cardiomyopathy and also exhibiting concomitant tricuspid valve insufficiency due to annular dilation underwent VAD implantation and tricuspid valve annuloplasty. Extracorporeal circulation was established via the ascending aorta, superior vena cava, and right atrium. In all four cases the LVAD implantation and tricuspid valve repair via partial median sternotomy was successful. During the operative procedure, no conversion to full sternotomy was necessary. One patient needed postoperative re-exploration because of pericardial effusion. No postoperative focal neurologic injury was observed. New generation VADs are advantageous because of the possibility of minimally invasive implantation procedure which can therefore minimize surgical trauma. Concomitant tricuspid valve reconstruction can also be performed simultaneously through partial upper sternotomy. Nevertheless, minimally invasive LVAD implantation is a challenging operative technique.

Mechanical Circulatory Support Devices for Pediatric Patients With Congenital Heart Disease.

The use of mechanical circulatory support (MCS) devices is a viable therapeutic treatment option for patients with congestive heart failure. Ventricular assist devices, cavopulmonary assist devices, and total artificial heart pumps continue to gain acceptance as viable treatment strategies for both adults and pediatric patients as bridge-to-transplant, bridge-to-recovery, and longer-term circulatory support alternatives. We present a review of the current and future MCS devices for patients having congenital heart disease (CHD) with biventricular or univentricular circulations. Several devices that are specifically designed for patients with complex CHD are in the development pipeline undergoing rigorous animal testing as readiness experiments in preparation for future clinical trials. These advances in the development of new blood pumps for patients with CHD will address a significant unmet clinical need, as well as generally improve innovation of the current state of the art in MCS technology.

Physics-driven impeller designs for a novel intravascular blood pump for patients with congenital heart disease.

Mechanical circulatory support offers an alternative therapeutic treatment for patients with dysfunctional single ventricle physiology. An intravascular axial flow pump is being developed as a cavopulmonary assist device for these patients. This study details the development of a new rotating impeller geometry. We examined the performance of 8 impeller geometries with blade stagger or twist angles varying from 100° to 800° using computational methods. A refined range of blade twist angles between 300° and 400° was then identified, and 4 additional geometries were evaluated. Generally, the impeller designs produced 4-26mmHg for flow rates of 1-4L/min for 6000-8000 RPM. A data regression analysis was completed and found the impeller with 400° of blade twist to be the superior performer. A hydraulic test was conducted on a prototype of the 400° impeller, which generated measurable pressure rises of 7-28mmHg for flow rates of 1-4L/min at 6000-8000 RPM. The findings of the numerical model and experiment were in reasonable agreement within approximately 20%. These results support the continued development of an axial-flow, mechanical cavopulmonary assist device as a new clinical therapeutic option for Fontan patients.

Vortical flow characteristics of mechanical cavopulmonary assistance: Pre- and post-swirl dynamics.

Surgical optimization of the cavopulmonary connection and pharmacological therapy for dysfunctional Fontan physiology continue to advance, but these treatment approaches only slow the progression of decline to end-stage heart failure. The development of a mechanical cavopulmonary assist device will provide a viable therapeutic option in the bridging of patients to transplant or to stabilization. We hypothesize that rotational blood flow, delivered by an implantable axial flow blood pump, could effectively assist the venous circulation in Fontan patients by mimicking vortical blood flow patterns in the cardiovascular system. This study investigated seven new models of mechanical cavopulmonary assistance (single and dual-pump assist), created combinations of pump designs that deliver counter rotating vortical flow conditions, and analyzed pump performance, velocity streamlines, swirling strength, and energy augmentation in the cavopulmonary circuit for each support scenario. The model having an axial clockwise-oriented impeller in the inferior vena cava and an axial counterclockwise-oriented impeller rotating in the superior vena cava outperformed all of the support scenarios by enhancing the energy of the cavopulmonary circulation an average of 10.3% over the entire flow range and a maximum of 27.4% at %the higher flow rates. This research will guide the development of axial flow blood pumps for Fontan patients and demonstrated the high probability of %a cardiovascular benefit using counter rotating pumps in a dual support scenario, but found that this is dependent upon the patient-specific cavopulmonary anatomy.

Pressure-Flow Experimental Performance of New Intravascular Blood Pump Designs for Fontan Patients.

An intravascular axial flow pump is being developed as a mechanical cavopulmonary assist device for adolescent and adult patients with dysfunctional Fontan physiology. Coupling computational modeling with experimental evaluation of prototypic designs, this study examined the hydraulic performance of 11 impeller prototypes with blade stagger or twist angles varying from 100 to 600 degrees. A refined range of twisted blade angles between 300 and 400 degrees with 20-degree increments was then selected, and four additional geometries were constructed and hydraulically evaluated. The prototypes met performance expectations and produced 3-31 mm Hg for flow rates of 1-5 L/min for 6000-8000 rpm. A regression analysis was completed with all characteristic coefficients contributing significantly (P < 0.0001). This analysis revealed that the impeller with 400 degrees of blade twist outperformed the other designs. The findings of the numerical model for 300-degree twisted case and the experimental results deviated within approximately 20%. In an effort to simplify the impeller geometry, this work advanced the design of this intravascular cavopulmonary assist device closer to preclinical animal testing.