Mechanical Circulatory Support for Bridge to Decision: Which Device and when to Decide

The impact of temporary mechanical circulatory support strategies on thrombocytopenia

One common but not well-understood phenomenon of temporary mechanical circulatory support (MCS) use is thrombocytopenia. This clinical issue increases the risk of bleeding and the need for platelet transfusion. Additionally, heparin-induced thrombocytopenia must be considered as part of the differential diagnosis, which complicates patient management. In what follows, we analyze the degree and relative rate of platelet count drop with various temporary MCS strategies - Impella 5.5; Veno-venous Extracorporeal Membrane Oxygenation (VV ECMO); Veno-arterial ECMO (VA ECMO); Intra-aortic Balloon Pump (IABP) and Centrimag Biventricular Assist Device (BIVAD). A total of 337 cohort was investigated. 77 was included for analysis after strict exclusion criteria were utilized (platelet transfusions, bleeding complications, etc.). Repeated measure mixed effect and linear regression models were used to assess the percent platelet drop on implantation of MCS and recovery after explantation of MCS. A statistically significant mean percent drop occurred in MCS types - VA ECMO(-69.6%, p < 0.001), VV ECMO(-40.9%, p < 0.001), Impella 5.5(-20.9%, p = 0.01) and IABP(-28.3%, p = 0.01), except Centrimag BIVAD(-6.5%, p = 0.61). Platelet recovery to or above baseline occurred in VA ECMO(+107.0%, p = 0.42), Impella 5.5(+117.2%, p = 0.28), IABP(+108.3%, p = 0.37), VV-ECMO(163.3%, p = 0.01*) and Centrimag BIVAD(+100.1%, p = 0.99). These results show that the degree of thrombocytopenia depends on MCS device type and is reversible.

Mock circulatory loop applications for testing cardiovascular assist devices and in vitro studies

The mock circulatory loop (MCL) is an in vitro experimental system that can provide continuous pulsatile flows and simulate different physiological or pathological parameters of the human circulation system. It is of great significance for testing cardiovascular assist device (CAD), which is a type of clinical instrument used to treat cardiovascular disease and alleviate the dilemma of insufficient donor hearts. The MCL installed with different types of CADs can simulate specific conditions of clinical surgery for evaluating the effectiveness and reliability of those CADs under the repeated performance tests and reliability tests. Also, patient-specific cardiovascular models can be employed in the circulation of MCL for targeted pathological study associated with hemodynamics. Therefore, The MCL system has various combinations of different functional units according to its richful applications, which are comprehensively reviewed in the current work. Four types of CADs including prosthetic heart valve (PHV), ventricular assist device (VAD), total artificial heart (TAH) and intra-aortic balloon pump (IABP) applied in MCL experiments are documented and compared in detail. Moreover, MCLs with more complicated structures for achieving advanced functions are further introduced, such as MCL for the pediatric application, MCL with anatomical phantoms and MCL synchronizing multiple circulation systems. By reviewing the constructions and functions of available MCLs, the features of MCLs for different applications are summarized, and directions of developing the MCLs are suggested.

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.

Temporary mechanical circulatory support: insights and evolving strategies

PURPOSE

The goal of this study is to evaluate the utilization and outcomes of temporary mechanical circulatory support (MCS) among patients listed for cardiac transplantation (CT). There is a constant threat of sudden clinical deterioration in these patients that could necessitate emergent MCS. All advanced heart failure and transplant centers in India are plagued by issues of late referrals, low organ donation rates, and financial constraints. Here, we share our experience and explain our evolving strategies tailored to improve outcomes.

METHODS

Single-center retrospective analysis of temporary MCS implanted in patients listed for CT from January 1, 2015, to December 31, 2019.

RESULTS

A total of 35 patients had 41 MCS implantations. Twenty-four cases were pre-transplant and 11 cases were post-transplant. Veno-arterial extracorporeal membrane oxygenator was the most commonly (20 cases, 44.4%) used MCS modality. Primary outcome of in-hospital mortality was noted in 17 patients (48.5%) in this high-risk profile. All but 2 of the 12 patients that underwent pre-transplant MCS, and were bridged to cardiac transplant, survived the index hospitalization accounting for 90% survival in this subset of patients. The secondary outcome of MCS-related vascular injury was observed in 9 patients (25.7%).

CONCLUSION

This single-center observational study demonstrates that early planning and timely institution of MCS improves outcomes in high-risk MCS patients bridged to cardiac transplant. The incidence of MCS-related vascular complications can be improved with development of standard operating protocols.

Temporary Mechanical Circulatory Support in Acute Heart Failure

Cardiogenic shock (CS) is a challenging syndrome, associated with significant morbidity and mortality. Although pharmacological therapies are successful and can successfully control this acute cardiac illness, some patients remain refractory to drugs. Therefore, a more aggressive treatment strategy is needed. Temporary mechanical circulatory support (TCS) can be used to stabilise patients with decompensated heart failure. In the last two decades, the increased use of TCS has led to several kinds of devices becoming available. However, indications for TCS and device selection are part of a complex process. It is necessary to evaluate the severity of CS, any early and prompt haemodynamic resuscitation, prior TCS, specific patient risk factors, technical limitations and adequacy of resources and training, as well as an assessment of whether care would be futile. This article examines options for commonly used TCS devices, including intra-aortic balloon pumps, a pulsatile percutaneous ventricular assist device (the iVAC), veno-arterial extra-corporeal membrane oxygenation and Impella (Abiomed) and TandemHeart (LivaNova) percutaneous ventricular assist device.

Miniaturized centrifugal ventricular assist device for bridge to decision: Preclinical chronic study in a bovine model

We developed a novel miniaturized extracorporeal centrifugal pump "BIOFLOAT NCVC (Nipro Corporation Osaka, Japan) as a ventricular assist device (VAD) and performed a preclinical study that is part of the process for its approval as a bridge to decision by the pharmaceutical and medical device agencies. The aim of this study was to assess the postoperative performance, hemocompatibility, and anticoagulative status during an extended period of its use. A VAD system, consisting of a hydrodynamically levitated pump, measuring 64 mm by 131 mm in size and weighing 635 g, was used. We installed this assist system in 9 adult calves (body weight, 90 ± 13 kg): as left ventricular assist device (LVAD) in 6 calves and right ventricular assist device (RVAD) in 3 calves, for over 30 days. Perioperative hemodynamic, hematologic, and blood chemistry measurements were obtained and end-organ effects on necropsy were investigated. All calves survived for over 30 days, with a good general condition. The blood pump was operated at a mean rotational speed and a mean pump flow of 3482 ± 192 rpm and 4.08 ± 0.15 L/min, respectively, for the LVAD and 3902 ± 210 rpm and 4.24 ± 0.3 L/min, respectively, for the RVAD. Major adverse events, including neurological or respiratory complications, bleeding events, and infection were not observed. This novel VAD enabled a long-term support with consistent and satisfactory hemodynamic performance and hemocompatibility in the calf model. The hemodynamic performance, hemocompatibility, and anticoagulative status of this VAD system were reviewed.

Assessment of Safety and Effectiveness of the Extracorporeal Continuous-Flow Ventricular Assist Device (BR16010) Use as a Bridge-to-Decision Therapy for Severe Heart Failure or Refractory Cardiogenic Shock: Study Protocol for Single-Arm Non-randomized, Uncontrolled, and Investigator-Initiated Clinical Trial

BACKGROUND

The management of heart failure patients presenting in a moribund state remains challenging, despite significant advances in the field of ventricular assist systems. Bridge to decision involves using temporary devices to stabilize the hemodynamic state of such patients while further assessment is performed and a decision can be made regarding patient management. The purpose of this study (NCVC-BTD_01, National Cerebral and Cardiovascular Center-Bridge to Dicision_01) is to assess the safety and effectiveness of the newly developed extracorporeal continuous-flow ventricular assist system employing a disposable centrifugal pump with a hydrodynamically levitated bearing (BR16010) use as a bridge-to-decision therapy for patients with severe heart failure or refractory cardiogenic shock.

METHOD/DESIGN

NCVC-BTD_01 is a single-center, single-arm, open-label, exploratory, medical device, investigator-initiated clinical study. It is conducted at the National Cerebral and Cardiovascular Center in Japan. A total of nine patients will be enrolled in the study. The study was planned using Simon's minimax two-stage phase design. The primary endpoint is a composite of survival free of device-related serious adverse events and complications during device support. For left ventricular assistance, withdrawal of a trial device due to cardiac function recovery or exchange to other ventricular assist devices (VADs) for the purpose of bridge to transplantation (BTT) during 30 days after implantation will be considered study successes. For right ventricular assistance, withdrawal of tal device due to right ventricular function recovery within 30 days after implantation will be considered a study success. Secondary objectives include changes in brain natriuretic peptide levels (7 days after implantation of a trial device and the day of withdrawal of a trial device), period of mechanical ventricular support, changes in left ventricular ejection fraction (7 days after implantation of a trial device and the day of withdrawal of a trial device), and changes in left ventricular diastolic dimension (7 days after implantation of a trial device and the day of withdrawal of a trial device).

ETHICS AND DISSEMINATION

We will disseminate the findings through regional, national, and international conferences and through peer-reviewed journals.

TRIAL REGISTRATION

UMIN Clinical Trials Registry (UMIN-CTR; R000033243) registered on 8 September 2017.

The neutrophil to lymphocyte ratio in patients supported with extracorporeal membrane oxygenation

INTRODUCTION

The neutrophil to lymphocyte ratio (NLR) has proven to be a robust predictor of mortality in a wide range of cardiovascular diseases. This study investigated the predictive value of the NLR in patients supported by extracorporeal membrane oxygenation (ECMO) systems.

METHODS

This study included 107 patients who underwent ECMO implantation for cardiogenic shock. Median preoperative NLR was used to divide the cohort, with Group 1 NLR <14.2 and Group 2 with NLR ≥14.2. Survival, the primary outcome, was compared between groups.

RESULTS

The study cohort was composed of 64 (60%) males with an average age 53.1 ± 14.9 years. Patients in Group 1 had an average NLR of 7.5 ± 3.5 compared to 27.1 ± 19.9 in Group 2. Additionally, those in Group 2 had significantly higher preoperative blood urea nitrogen (BUN) and age. Survival analysis indicated a thirty-day survival of 56.2%, with significantly worsened mortality in patients with NLR greater than 14.2, p=0.047.

DISCUSSION

Our study shows the NLR has prognostic value in patients undergoing ECMO implantation. Leukocytes are known contributors to myocardial damage and neutrophil infiltration is associated with damage caused by myocardial ischemia.

Novel temporary left ventricular assist system with hydrodynamically levitated bearing pump for bridge to decision: initial preclinical assessment in a goat model

The management of heart failure patients presenting in a moribund state remains challenging, despite significant advances in the field of ventricular assist systems. Bridge to decision involves using temporary devices to stabilize the hemodynamic state of such patients while further assessment is performed and a decision can be made regarding patient management. We developed a new temporary left ventricular assist system employing a disposable centrifugal pump with a hydrodynamically levitated bearing. We used three adult goats (body weight, 58-68 kg) to investigate the 30-day performance and hemocompatibility of the newly developed left ventricular assist system, which included the pump, inflow and outflow cannulas, the extracorporeal circuit, and connectors. Hemodynamic, hematologic, and blood chemistry measurements were investigated as well as end-organ effect on necropsy. All goats survived for 30 days in good general condition. The blood pump was operated at a rotational speed of 3000-4500 rpm and a mean pump flow of 3.2 ± 0.6 L min. Excess hemolysis, observed in one goat, was due to the inadequate increase in pump rotational speed in response to drainage insufficiency caused by continuous contact of the inflow cannula tip with the left ventricular septal wall in the early days after surgery. At necropsy, no thrombus was noted in the pump, and no damage caused by mechanical contact was found on the bearing. The newly developed temporary left ventricular assist system using a disposable centrifugal pump with hydrodynamic bearing demonstrated consistent and satisfactory hemodynamic performance and hemocompatibility in the goat model.

Heart failure with reduced ejection fraction

Heart failure is a global public health problem that affects more than 26 million people worldwide. The global burden of heart failure is growing and is expected to increase substantially with the ageing of the population. Heart failure with reduced ejection fraction accounts for approximately 50% of all cases of heart failure in the United States and is associated with substantial morbidity and reduced quality of life. Several diseases, such as myocardial infarction, certain infectious diseases and endocrine disorders, can initiate a primary pathophysiological process that can lead to reduced ventricular function and to heart failure. Initially, ventricular impairment is compensated for by the activation of the sympathetic nervous system and the renin-angiotensin-aldosterone system, but chronic activation of these pathways leads to worsening cardiac function. The symptoms of heart failure can be associated with other conditions and include dyspnoea, fatigue, limitations in exercise tolerance and fluid accumulation, which can make diagnosis difficult. Management strategies include the use of pharmacological therapies and implantable devices to regulate cardiac function. Despite these available treatments, heart failure remains incurable, and patients have a poor prognosis and high mortality rate. Consequently, the development of new therapies is imperative and requires further research.

DISPOSITIVOS DE ASSISTÊNCIA VENTRICULAR E CUIDADOS DE ENFERMAGEM

RESUMO Objetivo: descrever o funcionamento, os benefícios e as complicações associadas ao uso de dispositivos de assistência ventricular e identificar as intervenções realizadas por enfermeiros no cuidado ao paciente com este dispositivo, de acordo com as evidências. Método: revisão integrativa, com artigos coletados em bases de dados da saúde, em fevereiro de 2015. Os descritores utilizados foram heart diseases, heart-assist devices e nursing. Identificaram-se 34 artigos, os quais foram submetidos à análise temática. Resultados: os dispositivos de assistência ventricular funcionam como bombas mecânicas promotoras de débito cardíaco adequado. Seu principal benefício é a estabilização hemodinâmica. A complicação mais comum é a infecção. Educação em saúde, suporte emocional, cuidados com sítio de saída e realização de curativo são os principais cuidados realizados por enfermeiros. Conclusão: as evidências comprovam a melhoria da sobrevida de pacientes com insuficiência cardíaca grave com o uso dos dispositivos de assistência ventricular, reiterando a importância da ampliação dessa tecnologia no Brasil como possibilidade de tratamento.

Surgical implant techniques of left ventricular assist devices: an overview of acute and durable devices

Left ventricular support for the failing heart has evolved to include short-term and long-term devices. These devices are implanted percutaneously and surgically. This manuscript provides a general overview of the contemporary, typically practiced, implant techniques with additional insight on minimally invasive approaches.

Evaluation of erythrocyte flow at a bearing gap in a hydrodynamically levitated centrifugal blood pump

We have developed a hydrodynamically levitated centrifugal blood pump for extracorporeal circulatory support. In the blood pump, a spiral groove bearing was adopted for a thrust bearing. In the spiral groove bearing, separation of erythrocytes and plasma by plasma skimming has been postulated to occur. However, it is not clarified that plasma skimming occurs in a spiral groove bearing. The purpose of this study is to verify whether plasma skimming occurs in the spiral groove bearing of a hydrodynamically levitated centrifugal blood pump. For evaluation of plasma skimming in the spiral groove bearing, an impeller levitation performance test using a laser focus displacement meter and a microscopic visualization test of erythrocyte flow using a high-speed microscope were conducted. Bovine blood diluted with autologous plasma to adjust hematocrit to 1.0% was used as a working fluid. Hematocrit on the ridge region in the spiral groove bearing was estimated using image analysis. As a result, hematocrits on the ridge region with gaps of 45 μm, 31 μm, and 25 μm were calculated as 1.0%, 0.6%, and 0.3%, respectively. Maximum skimming efficiency in this study was calculated as 70% with a gap of 25 μm. We confirmed that separation of erythrocyte and plasma occurred in the spiral groove bearing with decrease in bearing gap in a hydrodynamically levitated centrifugal blood pump.

A Survey of Physicians' Attitudes toward Decision-Making Authority for Initiating and Withdrawing VA-ECMO: Results and Ethical Implications for Shared Decision Making

OBJECTIVE

Although patients exercise greater autonomy than in the past, and shared decision making is promoted as the preferred model for doctor-patient engagement, tensions still exist in clinical practice about the primary locus of decision-making authority for complex, scarce, and resource-intensive medical therapies: patients and their surrogates, or physicians. We assessed physicians' attitudes toward decisional authority for adult venoarterial extracorporeal membrane oxygenation (VA-ECMO), hypothesizing they would favor a medical locus.

DESIGN, SETTING, PARTICIPANTS

A survey of resident/fellow physicians and internal medicine attendings at an academic medical center, May to August 2013.

MEASUREMENTS

We used a 24-item, internet-based survey assessing physician-respondents' demographic characteristics, knowledge, and attitudes regarding decisional authority for adult VA-ECMO. Qualitative narratives were also collected.

MAIN RESULTS

A total of 179 physicians completed the survey (15 percent response rate); 48 percent attendings and 52 percent residents/fellows. Only 32 percent of the respondents indicated that a surrogate's consent should be required to discontinue VA-ECMO; 56 percent felt that physicians should have the right to discontinue VA-ECMO over a surrogate's objection. Those who self-reported as "knowledgeable" about VA-ECMO, compared to those who did not, more frequently replied that there should not be presumed consent for VA-ECMO (47.6 percent versus 33.3 percent, p = 0.007), that physicians should have the right to discontinue VA-ECMO over a surrogate's objection (76.2 percent versus 50 percent, p = 0.02) and that, given its cost, the use of VA-ECMO should be restricted (81.0 percent versus 54.4 percent, p = 0.005).

CONCLUSIONS

Surveyed physicians, especially those who self-reported as knowledgeable about VA-ECMO and/or were specialists in pulmonary/critical care, favored a medical locus of decisional authority for VA-ECMO. VA-ECMO is complex, and the data may (1) reflect physicians' hesitance to cede authority to presumably less knowledgeable patients and surrogates, (2) stem from a stewardship of resources perspective, and/or (3) point to practical efforts to avoid futility and utility disputes. Whether these results indicate a more widespread reversion to paternalism or a more circumscribed usurping of decisional authority occasioned by VA-ECMO necessitates further study.

Diagnosis and management of acute heart failure

Acute heart failure (AHF) is a life threatening clinical syndrome with a progressively increasing incidence in general population. Turkey is a country with a high cardiovascular mortality and recent national statistics show that the population structure has turned to an 'aged' population.As a consequence, AHF has become one of the main reasons of admission to cardiology clinics. This consensus report summarizes clinical and prognostic classification of AHF, its worldwide and national epidemiology, diagnostic work-up, principles of approach in emergency department,intensive care unit and ward, treatment in different clinical scenarios and approach in special conditions and how to plan hospital discharge.

Evaluation of a Spiral Groove Geometry for Improvement of Hemolysis Level in a Hydrodynamically Levitated Centrifugal Blood Pump

The purpose of this study is to evaluate a spiral groove geometry for a thrust bearing to improve the hemolysis level in a hydrodynamically levitated centrifugal blood pump. We compared three geometric models: (i) the groove width is the same as the ridge width at any given polar coordinate (conventional model); (ii) the groove width contracts inward from 9.7 to 0.5 mm (contraction model); and (iii) the groove width expands inward from 0.5 to 4.2 mm (expansion model). To evaluate the hemolysis level, an impeller levitation performance test and in vitro hemolysis test were conducted using a mock circulation loop. In these tests, the driving conditions were set at a pressure head of 200 mm Hg and a flow rate of 4.0 L/min. As a result of the impeller levitation performance test, the bottom bearing gaps of the contraction and conventional models were 88 and 25 μm, respectively. The impeller of the expansion model touched the bottom housing. In the hemolysis test, the relative normalized index of hemolysis (NIH) ratios of the contraction model in comparison with BPX-80 and HPM-15 were 0.6 and 0.9, respectively. In contrast, the relative NIH ratios of the conventional model in comparison with BPX-80 and HPM-15 were 9.6 and 13.7, respectively. We confirmed that the contraction model achieved a large bearing gap and improved the hemolysis level in a hydrodynamically levitated centrifugal blood pump.

Ventricular assist device selection: which one and when?

Advances in mechanical circulatory support have significantly expanded the treatment options for patients with heart failure, whether acute or chronic. There are numerous devices available that offer patients short-, intermediate-, and long-term duration of support depending on their clinical needs and cardiac recovery. Each device has its own technical considerations and the decision which device to use depends on several factors, including what is available, the degree of support required, and expected duration of support. Additional issues that need to be considered in choosing level of support include right heart function, respiratory failure, and multi-organ derangements. A widespread availability of short-term ventricular assist devices and timely institution for effective hemodynamic support will translate into improved patient outcomes whether that is successful transfer to a tertiary care facility or recovery of inherent cardiac function. Implantable ventricular assist devices have and will continue to evolve into smaller and more durable devices, and the future for patients with advanced heart failure looks ever-more promising.

Treatment strategies for patients with an INTERMACS I profile

Treatment of patients with INTERMACS class I heart failure can be very challenging, and temporary long-term device support may be needed. In this article, we review the currently available temporary support devices in order to support these severely ill patients with decompensated heart failure. Strategies of using a temporary assist as a bridge to long-term device support are also discussed.

Survival on biventricular mechanical support with the Centrimag® as a bridge to decision: a single-center risk stratification

Objective:

Temporary mechanical assist devices are increasingly being used as a lifesaving bridge to decision in patients requiring cardiopulmonary resuscitation. We report our single-center experience with biventricular Centrimag® pumps over a five-year period.

Method:

Data was retrospectively collected in consecutive patients who required biventricular support from 2008 to 2013. Patients who were supported with central cannulation using the Centrimag® system were analyzed. In addition to demographic information, data pertaining to indications, outcomes and mortality were collected.

Results:

The cohort consisted of 48 patients (19 women and 29 men, mean age of 56 years). The median duration of support was 14 days. The median duration to patient expiration while still on the Centrimag® was 12 days. Thirty-day survival was 56% (27/48). Nine patients were explanted to recovery, while fourteen patients were converted to a durable LVAD, two of whom were then transplanted. We stratified patients into two groups. Group I comprised patients who were either explanted to recovery, converted to durable LVAD or transplanted (23/48) and Group II consisted of patients who either died on the Centrimag® or were explanted for withdrawal of care (25/48). Statistical analysis did not reveal any clinically significant differences between the two groups in terms of age, sex, etiology, hemodynamic, co-morbidities or laboratory parameters.

Conclusion:

The biventricular Centrimag® can be used as a bridge to decision in patients with thirty-day survival of >50%. Parameters to predict 30-day survival in this high-risk cohort continue to remain elusive.

Left ventricular assist device outflow graft: alternative sites

We describe three alternative approaches for the left ventricular assist device (LVAD) outflow graft during implantation of the LVAD. The supraceliac abdominal aorta, innominate artery and left axillary artery were employed as alternative sites for the LVAD outflow graft in the setting of a heavily calcified ascending aorta or a hostile chest wall and mediastinum. The first approach involved the use of the supraceliac abdominal aorta. Given that the patient had a history of multiple previous breast surgeries and chest wall radiation for breast cancer treatment, a left subcostal incision was employed as a sternotomy-sparing approach. The second approach was the use of the innominate artery in a patient with a porcelain ascending aorta. The patient underwent pulmonary valve replacement, right ventricle outflow tract reconstruction and tricuspid valve annuloplasty in addition to the LVAD implantation. The third approach was the use of the left axillary artery. This patient had a history of LVAD implantation and subsequently developed infection with pseudoaneurysm formation at the aortic anastomosis of the outflow graft. We conclude that the supraceliac abdominal aorta, the innominate artery and the left axillary artery are potential alternative routes for the LVAD outflow graft in the settings of heavily calcified ascending aorta or a hostile chest wall and mediastinum. Although the described alternative approaches are safe and viable options, we highly recommend utilizing these approaches only in selected patients with significantly higher risks and hazards to the standard surgical approach.

Extracorporeal membrane oxygenation in adults: a brief review and ethical considerations for nonspecialist health providers and hospitalists

Given the pace, distribution, and uptake of technological innovation, patients experiencing respiratory failure, heart failure, or cardiac arrest are, with greater frequency, being treated with extracorporeal membrane oxygenation (ECMO). Although most hospitalists will not be responsible for ordering or managing ECMO, in-hospital healthcare providers continue to be a vital source of patient referral and, accordingly, need to understand the rudiments of these technologies so as to co-manage patients, counsel families, and help ensure that the provision of ECMO is consistent with patient preferences and appropriate goals of care. In an effort to prepare hospitalists for these clinical responsibilities, we review the history and technology behind modern-day ECMO, including venoarterial extracorporeal membrane oxygenation (VA-ECMO) and venovenous extracorporeal membrane oxygenation. Building upon that foundation, we further highlight special ethical considerations that may arise in VA-ECMO, and present an ethically grounded approach to the initiation, continuation, and discontinuation of treatment.

The 'Inextricabilis Syndrome': a case with no solution

We describe a case of a 58-year-old man with cardiogenic shock who underwent triple vessel coronary artery bypass and a left ventricular assist device (LVAD) implantation. His course was complicated by stroke, worsening mitral regurgitation, aortic regurgitation, and multiple cardiac thrombi while on the device. We provide the details of the patient's hospital course, management, and echocardiographic findings. We also discuss the utility of echocardiography before LVAD insertion and its role for continued monitoring after insertion.

LEARNING POINTS

Ventricular assist devices (VADs) are used as bridge to decision, transplant, recovery, or destination therapy in patients with advanced heart failure and cardiogenic shock.VADs improve survival and the quality of life but have significant associated complications.Echocardiography plays an essential role before VAD insertion and for postoperative cardiac monitoring. Information provided by echocardiography is used in device selection, consideration for corrective surgical interventions, and device explantation.

Current status of extracorporeal ventricular assist devices in Japan

Extracorporeal VADs are less expensive, their prices reimbursable by the health insurance being about one-sixth of those of implantable VADs in Japan. However, a disadvantage is that, in Japan, their use is restricted to hospitals, necessitating prolonged hospitalization, reducing the patients' quality of life. According to the Japanese registry for Mechanically Assisted Circulatory Support, the survival rate does not differ significantly between patients with extracorporeal and implantable VADs. As in Europe and North America, extracorporeal VADs in Japan are commonly used as Bridge to Decision or Bridge to Recovery. Extracorporeal VADs are switched to implantable VADs as a Bridge-to-Bridge strategy after stabilization or when cardiac function recovery fails. They are also used as right ventricular assist devices (RVADs) in patients with right heart failure. A special characteristic of extracorporeal VADs in Japan is their frequent use as a Bridge to Candidacy. In Japan, indications for implantable VADs are restricted to patients registered for heart transplantation. Therefore, in patients who cannot be registered for transplantation because of transient renal dysfunction, etc., due to heart failure, extracorporeal VADs are used first, and then replaced by implantable VADs after transplant registry is done. Here, we describe the current status of extracorporeal VADs in Japan, focusing on the environmental backgrounds, along with a review of the relevant literature.

A crisis of the heart: an acute reversible cardiomyopathy bridged to recovery in a patient with Addison's disease

Primary adrenal insufficiency or Addison's disease is a rare disorder often difficult to diagnose on presentation by the nature of its associated nonspecific symptoms, such as nausea or weakness. Cardiovascular complications of the condition are usually limited to hypovolemic hypotension; however, we highlight here a rare, dramatic case of a fulminant adrenal crisis in a young man primarily marked by acute biventricular systolic failure and cardiogenic shock. The patient was successfully treated with corticosteroid replacement and bridged with temporary mechanical circulatory support to eventual complete the recovery of native myocardial function.

Use of a single circuit to provide temporary mechanical respiratory and circulatory support in patients with LV apical thrombus and cardiogenic shock

Introduction:

Techniques to support patients with cardiogenic shock continue to improve. Patients with intracardiac thrombi pose a potential for additional complications. Novel methods of biventricular support are necessary to manage these patients.

Methods:

Two patients with refractory cardiogenic shock and left ventricular apical thrombi underwent mechanical circulatory support (MCS) as a bridge to decision, with a left ventricular assist device (LVAD) and extracorporeal mechanical oxygenation (ECMO). Instead of the conventional LV apical cannulation for LVAD, the left atrium (LA) was cannulated. The LA cannula was then integrated with the ECMO circuit via a ‘Y’ connection to a percutaneous right atrial cannula, enabling optimal drainage of both sides into one circuit through a single CentriMag® pump and ECMO into the aorta.

Results:

The first patient was converted to a durable LVAD and transplanted, while the second patient was explanted, after demonstrating significant LV recovery.

Conclusion:

We demonstrated the use of MCS as a bridge to decision in patients with LV thrombi, utilizing biatrial cannulation with a ‘Y’ connection to drain both right- and left-sided circulation through a single circuit and pump.

Additive effect of propofol and fentanyl precipitating cardiogenic shock

The intravenous administration of propofol and fentanyl has become a common practice in a variety of clinical settings including outpatient dermatologic, cosmetic and oral surgery. The combination provides both systematic sedation and analgesia with low incidence of unwanted side effects. The cardiogenic shock is very uncommon in healthy individuals. The cardiovascular depressive effect of propofol and fentanyl has been well established, but the development of cardiogenic shock is very rare when these drugs are used together. Hence the awareness of this effect is advantageous to the patients undergoing such surgeries

Mechanical circulatory support for cardiogenic shock

Cardiogenic shock (CS) is a syndrome of progressive depression of myocardial function with systemic hypoperfusion. It occurs due to various aetiologies such as acute myocardial infarction, myocarditis, acute decompensated heart failure and postcardiotomy. Cardiogenic shock carries poor prognosis, and medical therapy alone is not effective. Mechanical circulatory support is required to unload the ventricles, decrease the myocardial demand, prevent further injury, improve the coronary perfusion, stabilise the haemodynamics and maintain the end-organ perfusion before definitive interventions such as coronary reperfusion can take place. Currently, there are several methods of mechanical circulatory support. These include extracorporeal life support, paracorporeal or extracorporeal ventricular-assist devices, percutaneous ventricular assist devices, intra-aortic balloon counterpulsation and total artificial heart. In this review, we discuss the role of each of these circulatory support devices in the management of acute cardiac failure.

Platelet activation after implantation of the Levitronix PediVAS in the ovine model

The Levitronix PediVAS is an extracorporeal magnetically levitated pediatric ventricular assist system with an optimal flow rate range of 0.3-1.5 L/min. The system is being tested in preclinical studies to assess hemodynamic performance and biocompatibility. The PediVAS was implanted in nine ovines for 30 days using either commercially available cannulae (n = 3) or customized Levitronix cannulae (n = 6). Blood biocompatibility in terms of circulating activated platelets was measured by flow cytometric assays to detect P-selectin. Platelet activation was further examined after exogenous agonist stimulation. Platelet activation increased after surgery and eventually returned to baseline in animal studies where minimal kidney infarcts were observed. Platelet activation remained elevated for the duration of the study in animals where a moderate number of kidney infarcts with or without thrombotic deposition in the cannulae were observed. When platelet activation did return to baseline, platelets appropriately responded to agonist stimulation, signifying conserved platelet function after PediVAS implant. Platelet activation returned to baseline in the majority of studies, representing a promising biocompatibility result for the Levitronix PediVAS.

Preliminary in vivo testing of a novel pump for short-term extracorporeal life support

BACKGROUND

Blood pumps used for temporary circulatory support have limitations. We propose a novel device designed for short-term extracorporeal support that is intrinsically volume responsive, afterload insensitive, and incapable of cavitation or excessive hemolysis. After in vitro testing, we performed the initial in vivo implantations and assessments.

METHODS

The BioVAD prototype (MC3, Inc, Ann Arbor, MI) was implanted in 6 adult male sheep (60.2±2.8 kg) through the left ventricular apex and descending thoracic aorta. Arterial, left and right atrial, and pump inlet and outlet pressures and BioVAD flow were measured and recorded. The animals were volume loaded to assess volume responsiveness, and the inlet lines were abruptly clamped during maximum support to observe for cavitation. An acute heart failure model was created with rapid ventricular pacing, and the animals were supported for 4 hours.

RESULTS

Peak flow was 3.19±0.56 L/min and increased to 3.71±0.53 L/min with 20 mm Hg vacuum-assisted drainage. Without manual changes in pump settings, pump flow increased 17.5% with volume loading. During acute venous line occlusion, there was no evidence of cavitation, and inlet suction was minimal. Hemodynamics were maintained for 4 hours during acute heart failure.

CONCLUSIONS

The BioVAD provided adequate flow in an acute in vivo model. Its design may be superior for short-term extracorporeal support.

Perioperative mechanical circulatory support in children with critical heart disease

OPINION STATEMENT

The treatment of cardiovascular failure in the perioperative period with the use of mechanical circulatory support is a well-recognized, well-developed, and commonly utilized treatment modality. Regardless of the exact circumstances of initiation, the use of a support device is a "bridge." Where there has been an acute myocardial insult, short-term assist devices can serve as a "bridge to immediate survival," a "bridge to recovery," or even a "bridge to the next decision." Mechanical circulatory support can serve as a treatment of cardiovascular decompensation caused by myocarditis, acute myocardial insult, low cardiac output following surgery, and congenital heart disease. The utilization of such support carries significant risks such as bleeding, infection, and thrombosis. However, these can be minimized in order to allow for the safe and effective deployment of this therapeutic strategy. One specific therapeutic domain in which these devices provide immediate impact is during cardiac arrest. Although outcomes of cardiac arrest remain poor, use of a mechanical device as an intervention has allowed salvage of otherwise certain mortality. However, it is important to note that the utility of support was most pronounced in patients that were not on either extreme of the survival prediction curve. This can be best summarized by the concept of "not too early, not too late." Therefore, it is the responsibility of the entire care team to find the appropriate patient population in which to "pull the trigger" on mechanical support as a therapy. This decision point is supported by a monitoring strategy that can be utilized to predict deterioration and intervene adequately. Most importantly, an effective monitoring strategy allows the practitioner to judge the effectiveness of treatment and support strategies and make adjustments in a timely manner, potentially with mechanical support in the perioperative period.