A first-in-man study of the reitan catheter pump for circulatory support in patients undergoing high-risk percutaneous coronary intervention

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

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

Assessment of Large Animal Vascular Dimensions for Intra-Aortic Device Research and Development: A Systematic Review

Animal studies are often required to evaluate new cardiovascular medical devices before they reach the market. Moreover, first-generation novel devices including aortic endovascular prostheses and circulatory support devices are often larger than later iterations or tested in a limited range of sizes. One of the challenges in evaluating these devices is finding a model that is both accessible and anatomically similar to humans, as there is a paucity of data on vascular dimensions in large animals. We set out to complete a comprehensive review of available reports on vascular dimensions in swine, ovine, and bovine models, with a particular focus on the descending aorta and ilio-femoral arteries. We searched Embase and MEDLINE databases for reports of descending aorta and peripheral vascular dimension in large animal models. Data from swine, ovine, and bovine models were separated by weight into 3 categories: 40 to 60 kg, 61 to 80 kg, and >80 kg. We also incorporate our computed tomography angiography data from 4 large sheep and 9 calves into this review. Swine, sheep, and calf >80 kg may serve as the best models to maximize aortic diameter resemblance to humans. If device implantation can be achieved in aortas of smaller dimensions, care should be taken to ensure access site suitability such as the common femoral artery in these smaller animals.

Device-based therapy for decompensated heart failure: An updated review of devices in development based on the DRI2P2S classification

Congestive heart failure (HF) is a devastating disease leading to prolonged hospitalization, high morbidity and mortality rates, and increased costs. Well-established treatments for decompensated or unstable patients include medications and mechanical cardiac support devices. For acute HF decompensation, new devices are being developed to help relieve symptoms and recover heart and renal function in these patients. A recent device-based classification scheme, collectively classified as DRI2P2S, has been proposed to better describe these new device-based therapies based on their mechanism: dilators (increase venous capacitance), removers (direct removal of sodium and water), inotropes (increase left ventricular contractility), interstitials (accelerate removal of lymph), pushers (increase renal arterial pressure), pullers (decrease renal venous pressure), and selective (selective intrarenal drug infusion). In this review, we describe the new class of medical devices with the most current results reported in preclinical models and clinical trials.

First-in-Man Use of the Percutaneous 10F Reitan Catheter Pump for Cardiorenal Syndrome

Cardiorenal syndrome worsens outcome in patients with decompensated chronic heart failure, and complicates recompensation by medical therapy. Mechanical circulatory support has the potential to improve renal function, and likely mitigates diuretic resistance in patients with severe cardiorenal syndrome. The Reitan catheter pump (RCP) is a novel temporary percutaneous circulatory support system for reducing cardiac afterload and increasing renal preload. Here, we report on the first-in-man use of the 10F-version of the RCP device, which was associated with favorable effects on hemodynamics and diuresis. Further investigation to evaluate safety and efficacy of this promising approach is warranted.

A Glimpse Into the Future of Transcatheter Interventional Heart Failure Therapies

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HF affects millions of patients every year, adding a significant financial burden to global health care systems.

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This review discusses the role of novel transcatheter-based therapies for the management of HF.

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Ongoing clinical trials will provide answers on the potential clinical benefits of these technologies in HF outcomes.

Chronic heart failure is one of the most debilitating chronic conditions affecting millions of people and adding a significant financial burden to health care systems worldwide. Despite the significant therapeutic advances achieved over the last decade, morbidity and mortality remain high. Multiple catheter-based interventional therapies targeting different physiological and anatomical targets are already under different stages of clinical investigation. The present paper provides a technical overview of the most relevant catheter-based interventional therapies under clinical investigation.

Future Devices for Percutaneous Mechanical Circulatory Support

Percutaneous mechanical circulatory support options include intra-aortic balloon pump, transvalvular axial flow pumps, left atrial to femoral artery pumping, and oxygenated right atrium to femoral artery circuits. Percutaneous mechanical circulatory support devices providing greater support have not proven superiority over the intra-aortic balloon pump. Novel counterpulsation devices target durability and ambulatory capability and direct unloading of left ventricle (LV) and right ventricle. Device innovations in transvalvular axial pumping include miniaturization of partial-support devices and development of larger self-expanding devices for near-complete LV support. Aortic entrainment pumping is a novel mode of blood displacement with potential benefits beyond reduced LV afterload.

Aortix™: a novel intra-aortic entrainment pump

Use of short-term mechanical circulatory support pumps for cardiogenic shock, decompensated heart failure and high-risk coronary intervention is growing. The Aortix™ device (Procyrion, TX, USA) is the first axial-flow pump positioned in the aorta and is designed to provide short-term hemodynamic support. This review discusses the field of continuous flow aortic pumps and focuses specifically on emerging preclinical and clinical data supporting the development of these technologies.

A role for the Reitan catheter pump for percutaneous cardiac circulatory support of patients presenting acute congestive heart failure with low output and renal dysfunction?

Outcomes in acute decompensated heart failure remain poor, in particular when patients present with impaired renal function. Recent results indicate that treatment of acute decompensated heart failure patients with the Reitan catheter pump not only increases cardiac index, but also improves renal function resulting in maintained increase of diuresis. These favorable effects were achieved without significant hemolysis, bleeding or vascular complications suggesting that Reitan catheter pump treatment has the potential to facilitate recovery from acute decompensated heart failure with low output and complicated by renal dysfunction.

Management of cardiogenic shock complicating acute myocardial infarction: A review

Despite advances in percutaneous coronary interventions and their widespread use, mortality in patients presenting with acute myocardial infarction (MI) complicated by cardiogenic shock (CS) has remained very high, and treatment options are limited. Limited evidences exist, supporting many of the routinely used therapies in treating these patients. In the present article, we discuss CS complicating MI in general and an update on the currently available treatment options, including inotropes and vasopressor, coronary revascularization, mechanical circulatory support devices, mechanical complications, and long‐term outcomes.

[Mechanical circulatory support in cardiogenic shock]

Acute revascularization is of utmost importance in acute heart failure and infarct-related cardiogenic shock. Besides this therapy of the underlying disease, methods for rapid restoration of arterial blood pressure and sufficient organ perfusion are at the forefront. If conventional means such as volume management, inotropic support, or infusion of vasopressors fail in this situation, mechanical circulatory support may be indicated in selected cases. Noninvasive systems for automatic thorax compression are used for extended cardiopulmonary resuscitation. Intra-aortic balloon counter pulsation (IABP) and axial turbine pumps provide circulatory support and left ventricular unloading. Extracorporeal membrane oxygenation (ECMO) devices consisting of a membrane oxygenator in combination with a centrifugal pump also support the gas exchange in cases of acute pulmonary failure. Using mechanical circulatory support allows lifesaving further diagnostic and therapeutic measures in selected cases, despite limited evidence. They help to restore sufficient arterial blood pressure and therefore organ perfusion in acute heart failure and cardiogenic shock.

Hemodynamic Benefits of Counterpulsation, Implantable, Percutaneous, and Intraaortic Rotary Blood Pumps: An In-Silico and In Vitro Study

Mechanical circulatory support (MCS) devices have become a standard therapy for heart failure (HF) patients. MCS device designs may differ by level of support, inflow and/or outflow cannulation sites, and mechanism(s) of cardiac unloading and blood flow delivery. Investigation and direct comparison of hemodynamic parameters that help characterize performance of MCS devices has been limited. We quantified cardiac and vascular hemodynamic responses for different types of MCS devices. Continuous flow (CF) left ventricular (LV) assist devices (LVAD) with LV or left atrial (LA) inlet, counterpulsation devices, percutaneous CF LVAD, and intra-aortic rotary blood pumps (IARBP) were quantified using established computer simulation and mock flow loop models. Hemodynamic data were analyzed on a beat-to-beat basis at baseline HF and over a range of MCS support. Results demonstrated that all LVAD greatly diminished vascular pulsatility (P) and LV external work (LVEW). LVAD with LA inflow provided a greater reduction in LVEW compared to LVAD with LV inflow, but at the potential risk for blood stasis/thrombosis in the LV at high support. Counterpulsation provided greater coronary flow (CoF) augmentation, but had a lower reduction in LVEW compared to partial percutaneous LVAD support. IARBP diminished LVEW, but at the expense of diminished CoF due to coronary steal. The hemodynamic benefits for each type of mechanical circulatory support system are unique and clinical decisions on device selection to maximize end organ perfusion and minimize invasiveness needs to be considered for an individual patients' presentation.

In-vitro investigation of the hemodynamic responses of the cerebral, coronary and renal circulations with a rotary blood pump installed in the descending aorta

This study investigates the hemodynamic responses of the cardiovascular system when a rotary blood pump is operating in the descending aorta, with a focus on the cerebral, coronary and renal autoregulation, using our in-house cardiovascular emulator. Several improvements have been made from our previous studies. A novel coronary system was developed to replicate the native coronary perfusion. Three pinch valves actuated by stepper motors were used to simulate the regional autoregulation systems of the native cerebral, coronary and renal circulations. A rotary pump was installed in the descending aorta, in series with the heart, and the hemodynamic responses of the cardiovascular system were investigated with a focus on cerebral, coronary and renal circulation over a wide range of pump rotor speeds. Experiments were performed twice, once with the autoregulation systems active and once with the autoregulation systems inactive, to reflect that there will be some impairment of autoregulatory systems in a patient with heart failure. It was shown that by increasing the rotor speed to 3000 rpm, the cardiac output was improved from 2.9 to 4.1 L/min as a result of an afterload reduction induced by the pressure drop upstream of the pump. The magnitudes of changes in perfusion in the cerebral, coronary and renal circulations were recorded with regional autoregulation systems active and inactive.

In-vitro investigation of cerebral-perfusion effects of a rotary blood pump installed in the descending aorta

This study describes use of a cardiovascular simulator to replicate the hemodynamic responses of the cerebrovascular system with a mechanical circulatory support device operating in the descending aorta. To do so, a cerebral autoregulation unit was developed which replicates the dilation and constriction of the native cerebrovascular resistance system and thereby regulates the cerebral flow rate within defined limits. The efficacy of the replicated autoregulation mechanism was investigated by introducing a number of step alterations in mean aortic pressure and monitoring the cerebral flow. The steady responses of the cerebral flow to changes in mean aortic pressure were in good agreement with clinical data. Next, a rotary pump, modeling a mechanical circulatory support device, was installed in the descending aorta and the hemodynamic responses of the cerebral system were investigated over a wide range of pump operating conditions. Insertion of a mechanical circulatory support device in the descending aorta presented an improved cardiac output as a result of afterload reduction. It was observed that the primary drop in cerebral flow, caused by the pump in the descending aorta, was compensated over the course of five seconds due to a gradual decrease in cerebrovascular resistance. The experimental results suggest that the implantation of a mechanical circulatory support device in the descending aorta, a less invasive procedure than typical mechanical circulatory support implantation, will not have an adverse effect on the cognitive function, provided that the cerebral autoregulation is largely unimpaired.

Short-term continuous-flow ventricular assist devices

PURPOSE OF REVIEW

To provide a comprehensive update on the current state of short-term, continuous-flow ventricular assist devices (CF-VADs) in the treatment of refractory cardiogenic shock in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) 1 patients.

RECENT FINDINGS

The mortality rate associated with refractory cardiogenic shock remains markedly elevated, with INTERMACS 1 profile repeatedly demonstrating the worst outcomes. Recent innovations in continuous-flow pump technology have not only contributed to improved outcomes with long-term left ventricular assist device technology, but have also led to the development of various short-term, percutaneous, and surgical CF-VADs. Short-term CF-VADs have several favorable features, but, most notably, they allow the effective temporary stabilization of otherwise refractory cardiogenic shock and serve as a bridge-to-decision therapy.

SUMMARY

Clinical evidence supporting the use of CF-VADs still remains at the level of small case series, but the data appear promising. However, further rigorous clinical investigation is necessary in order to prove the overall clinical efficacy of these devices in refractory cardiogenic shock.

An insight into short- and long-term mechanical circulatory support systems

Cardiogenic shock due to acute myocardial infarction, postcardiotomy syndrome following cardiac surgery, or manifestation of heart failure remains a clinical challenge with high mortality rates, despite ongoing advances in surgical techniques, widespread use of primary percutaneous interventions, and medical treatment. Clinicians have, therefore, turned to mechanical means of circulatory support. At present, a broad range of devices are available, which may be extracorporeal, implantable, or percutaneous; temporary or long term. Although counter pulsation provided by intra-aortic balloon pump (IABP) and comprehensive mechanical support for both the systemic and the pulmonary circulation through extracorporeal membrane oxygenation (ECMO) remain a major tool of acute care in patients with cardiogenic shock, both before and after surgical or percutaneous intervention, the development of devices such as the Impella or the Tandemheart allows less invasive forms of temporary support. On the other hand, concerning mid-, or long-term support, left ventricular assist devices have evolved from a last resort life-saving therapy to a well-established viable alternative for thousands of heart failure patients caused by the shortage of donor organs available for transplantation. The optimal selection of the assist device is based on the initial consideration according to hemodynamic situation, comorbidities, intended time of use and therapeutic options. The present article offers an update on currently available mechanical circulatory support systems (MCSS) for short and long-term use as well as an insight into future perspectives.

In vitro comparison of two different mechanical circulatory support devices installed in series and in parallel

This study investigates the novel approach of placing a ventricular assist pump in the descending aorta in series configuration with the heart and compares it with the two traditional approaches of left-ventricle-to-ascending-aorta (LV-AA) and left-ventricle-to-descending-aorta (LV-DA) placement in parallel with the heart. Experiments were conducted by using the in-house simulator of the cardiovascular blood-flow loop (SCVL). The results indicate that the use of the LV-AA in-parallel configuration leads to a significant improvement in the systemic and pulmonic flow as the level of continuous flow is increased; however, this approach is considered highly invasive. The use of the LV-DA in-parallel configuration leads to an improvement in the systemic and pulmonic flow at lower levels of continuous flow but at higher levels of pump support leads to retrograde flow. In both in-parallel configurations, increasing the level of pump continuous flow leads to a decrease in pulsatility to a certain extent. The results of placing the pump in the descending aorta in series configuration show that the pressure drop upstream of the pump facilitates cardiac output as a result of afterload reduction. In addition, the pressure rise downstream of the pump may assist with renal perfusion. However, at the same time, the pressure drop generated at the proximal part of the descending aorta induces a slight drop in carotid perfusion, which would be autoregulated by the brain in a native cardiovascular system. The pulse wave analysis shows that placing the pump in the descending aorta leads to improved pulsatility in comparison with the traditional in-parallel configurations.

In vitro cardiovascular system emulator (bioreactor) for the simulation of normal and diseased conditions with and without mechanical circulatory support

This article presents a new device designed to simulate in vitro flow rates, pressures, and other parameters representing normal and diseased conditions of the human cardiovascular system. Such devices are sometimes called bioreactors or "mock" simulator of cardiovascular loops (SCVLs) in literature. Most SCVLs simulate the systemic circulation only and have inherent limitations in studying the interaction of left and right sides of circulation. Those SCVLs that include both left and right sides of the circulation utilize header reservoirs simulating cycles with constant atrial pressures. The SCVL described in this article includes models for all four chambers of the heart, and the systemic and pulmonary circulation loops. Each heart chamber is accurately activated by a separate linear motor to simulate the suction and ejection stages, thus capturing important features in the perfusion waveforms. Four mechanical heart valves corresponding to mitral, pulmonary, tricuspid, and aortic are used to control the desired unidirectional flow. This SCVL can emulate different physiological and pathological conditions of the human cardiovascular system by controlling the different parameters of blood circulation through the vascular tree (mainly the resistance, compliance, and elastance of the heart chambers). In this study, four cases were simulated: healthy, congestive heart failure, left ventricular diastolic dysfunction conditions, and left ventricular dysfunction with the addition of a mechanical circulatory support (MCS) device. Hemodynamic parameters including resistance, pressure, and flow have been investigated at aortic sinus, carotid artery, and pulmonary artery, respectively. The addition of an MCS device resulted in a significant reduction in mean blood pressure and re-establishment of cardiac output. In all cases, the experimental results are compared with human physiology and numerical simulations. The results show the capability of the SCVL to replicate various physiological and pathological conditions with and without MCS.

Future Directions for Percutaneous Mechanical Circulatory Support Devices

Outcomes of patients in cardiogenic shock remain high, but the development of novel percutaneous mechanical circulatory support devices offers additional therapeutic options. Hand in hand with innovations in device technology, however, must also come development of integrated circulatory support networks focusing on rapid assessment of patients, multidisciplinary discussion, and timely therapeutic intervention. This article summarizes some of the recent developments in device technology; potential procedures for patient risk stratification, device selection, and response to therapy; management of vascular access to reduce insertion point complications; and some of the expanding potential roles of percutaneous mechanical circulatory support devices.

Cardiogenic Shock: Background, Shock Trial/Registry, Evolving Data, Changing Survival, Best Medical Therapy

Cardiogenic shock remains associated with unacceptably high mortality, but recent improvements with early revascularization, continued support with pharmacologic agents, and use of an intra-aortic balloon pump have led to improvements in the rate of mortality. Timely intervention with cardiac surgery in patients with mechanical complications, 3-vessel disease, and left main disease is beneficial. Continued research and ever-improving understanding of this once deadly condition have helped further in improving prognosis. Cutting-edge technologies, such as myocyte cell implantation and the use of a cooling system, will help in pushing the boundaries farther.

Controlled pitch-adjustment of impeller blades for an intravascular blood pump

Thousands of mechanical blood pumps are currently providing circulatory support, and the incidence of their use continues to increase each year. As the use of blood pumps becomes more pervasive in the treatment of those patients with congestive heart failure, critical advances in design features to address known limitations and the integration of novel technologies become more imperative. To advance the current state-of-the-art in blood pump design, this study investigates the inclusion of pitch-adjusting blade features in intravascular blood pumps as a means to increase energy transfer; an approach not explored to date. A flexible impeller prototype was constructed with a configuration to allow for a variable range of twisted blade geometries of 60-250°. Hydraulic experiments using a blood analog fluid were conducted to characterize the pressure-flow performance for each of these twisted positions. The flexible, twisted impeller was able to produce 1-25 mmHg for 0.5-4 L/min at rotational speeds of 5,000-8,000 RPM. For a given twisted position, the pressure rise was found to decrease as a function of increasing flow rate, as expected. Generally, a steady increase in the pressure rise was observed as a function of higher twisted degrees for a constant rotational speed. Higher rotational speeds for a specific twisted impeller configuration resulted in a more substantial pressure generation. The findings of this study support the continued exploration of this unique design approach in the development of intravascular blood pumps.

Percutaneous Left Ventricular Assist Devices

Percutaneous left ventricular assist devices (P-LVADs) can be life saving and may permit the stabilization of a patient in cardiovascular collapse who would otherwise face imminent demise. For specific patients and clinical indications, or where a greater degree of hemodynamic support is required, numerous studies have demonstrated the feasibility and safety of the newer generation P-LVADs. The potential applications for P-LVADs have continued to expand, now including diverse uses such as support for cardiogenic shock, bridge to and following cardiac surgery, and more novel applications such as complex electrophysiologic mapping and ablation studies of unstable ventricular rhythms.

The future of adult cardiac assist devices: novel systems and mechanical circulatory support strategies

The recent, widespread success of mechanical circulatory support has prompted the development of numerous implantable devices to treat advanced heart failure. It is important to raise awareness of novel device systems, the mechanisms by which they function, and implications for patient management. This article discusses devices that are being developed or are in clinical trials. Devices are categorized as standard full support, less-invasive full support, partial support: rotary pumps, partial support: counterpulsation devices, right ventricular assist device, and total artificial heart. Implantation strategy, mechanism of action, durability, efficacy, hemocompatibility, and human factors are considered. The feasibility of novel strategies for unloading the failing heart is examined.

Percutaneous ventricular assist devices: new deus ex machina?

The development of ventricular assist devices has broadened the means with which one can treat acute heart failure. Percutaneous ventricular assist devices (pVAD) have risen from recent technological advances. They are smaller, easier, and faster to implant, all important qualities in the setting of acute heart failure. The present paper briefly describes the functioning and assets of the most common devices used today. It gives an overview of the current evidence and indications for left ventricular assist device use in cardiogenic shock and high-risk percutaneous coronary intervention. Finally, extracorporeal life support devices are dealt with in the setting of hemodynamic support.

Contrast-induced acute kidney injury: the at-risk patient and protective measures

Contrast-induced acute kidney injury (CI-AKI) is a major complication following radiocontrast procedures. In this review, we characterize the recent literature on CI-AKI, risk factors, prevention, biomarkers, and new technologies. The premise of CI-AKI prophylaxis should focus on implementing mandatory standing orders before and after cardiac catheterization for hydration with normal saline or sodium bicarbonate and use of high-dose (1200-mg) N-acetylcysteine. Contrast agents may play a role in preventing CI-AKI. Implement catheter-laboratory technology and awareness to limit the amount of contrast dye used for any patient.