New era for therapeutic strategy for heart failure: destination therapy by left ventricular assist device

Surgical outcomes of bridge-to-bridge therapy with extracorporeal left ventricular assist device for acute myocardial infarction in cardiogenic shock

Background

Extracorporeal left ventricular assist device is often required for acute myocardial infarction patients in cardiogenic shock when temporary mechanical circulatory support fails to provide hemodynamic stabilization. This study aimed to evaluate the clinical outcomes of acute myocardial infarction patients in cardiogenic shock supported by an extracorporeal left ventricular assist device.

Methods

This retrospective study enrolled 13 acute myocardial infarction patients in cardiogenic shock treated with an extracorporeal left ventricular assist device from April 2011 to July 2020.

Results

Twelve (92.3%) and eleven (84.6%) patients were supported using venoarterial extracorporeal membrane oxygenation and intra-aortic balloon pumping before implantation, respectively. The median duration from acute myocardial infarction to extracorporeal left ventricular assist device implantation was 7 (3.5–24.5) days. The overall in-hospital mortality rate was 30.8% (n = 4). Extracorporeal left ventricular assist device was explanted in one patient for cardiac recovery; eight (61.5%) patients were approved as heart transplant candidates in whom the extracorporeal left ventricular assist device was exchanged for a durable left ventricular assist device; two (15.4%) expired while waiting for a heart transplant, and two (15.4%) received a successful transplant. The 1- and 3-year overall survival rates after extracorporeal left ventricular assist device implantation were 68.3% and 49.9%, respectively.

Conclusions

The operative mortality after extracorporeal left ventricular assist device implantation in acute myocardial infarction patients in cardiogenic shock was favorable. Our strategy of early hemodynamic stabilization with extracorporeal left ventricular assist device implantation in these patients as a bridge-to-bridge therapy was effective in achieving better survival.

Systematic Left Ventricular Assist Device Implant Eligibility with Non-Invasive Assessment: The SIENA Protocol

In patients with end-stage left ventricular (LV) heart failure who receive LV assist device (LVAD) implantation, right ventricular (RV) failure represents a possible critical complication that heavily affects morbidity and mortality. Several clinical, laboratory, hemodynamic, and echocardiographic variables have been found to be associated with RV failure occurrence after surgery. Different models and risk scores have been proposed, with poor results. No accordance has ever been reached about RV pre-operative evaluation, and time has come to introduce a standardized systematic protocol for LVAD suitability assessment according to RV function. We analyzed imaging parameters associated with LVAD implantation-related RV failure, in order to identify the minimum number for pre-operative reliable prediction of post-operative RV failure. A few echocardiographic parameters have been identified as the most reliable, or promising, and reproducible tools in this field: free-wall RV longitudinal strain, RV fractional area change, RV sphericity index, and RV ejection fraction with 3D-echocardiography. We propose the Systematic LVAD Implant Eligibility with Non-invasive Assessment protocol–the SIENA protocol–as a new and simple way of pre-operative evaluation of patients candidates to LVAD implantation.

Stem Cell Therapy for the Heart: Blind Alley or Magic Bullet?

When stressed by ageing or disease, the adult human heart is unable to regenerate, leading to scarring and hypertrophy and eventually heart failure. As a result, stem cell therapy has been proposed as an ultimate therapeutic strategy, as stem cells could limit adverse remodelling and give rise to new cardiomyocytes and vasculature. Unfortunately, the results from clinical trials to date have been largely disappointing. In this review, we discuss the current status of the field and describe various limitations and how future work may attempt to resolve these to make way to successful clinical translation.

Successful left ventricular assist device re-implantation with omental covering for MDRP device infection

We present a case of paracorporeal left ventricular assist device (p-LVAD)-related infection, caused by multi-drug resistant Pseudomonas aeruginosae (MDRP), and successfully treated by p-LVAD re-implantation with omental covering. A 59-year-old man underwent p-LVAD implantation and coronary artery bypass grafting after percutaneous cardiopulmonary support and intra-aortic balloon pumping for cardiogenic shock due to acute myocardial infarction. Then, he was registered for heart transplantation. He suffered from blood stream infection causative organism of Pseudomonas aeruginosa, 2 months after that operation. He underwent re-median sternotomy and open drainage, 15 months after the p-LVAD implantation. However, he suffered from septic shock due to MDRP. He underwent p-LVAD re-implantation under hypothermic circulatory arrest and iodine gauze packing, followed by omental covering of the all artificial materials in his body 10 days after that operation. Soon after that, the infection was well controlled and the intravenous antibiotics could be discontinued 2 months after that operation. He successfully underwent heart transplantation, 17 months after that procedure. We concluded that p-LVAD re-implantation with omental covering is seemed to be useful in the treatment of massive device infection. This procedure might be a novel treatment for severe VAD-related infection until heart transplantation.

Nipro extra-corporeal left ventricular assist device fitting after left ventricular reconstruction with mitral valve plasty

Both left ventricular assist device and left ventricular reconstruction are treatment choices for severe heart failure conditions. Our institution performed a left ventricular assist device installation following a left ventricular reconstruction procedure on a 42-year-old male patient who presented with dilated cardiomyopathy and low cardiac output syndrome. A mitral valve plasty was used to correct the acute mitral valve regurgitation and we performed a Nipro extra-corporeal left ventricular assist device installation on post-operative day 14. Due to the left ventricular reconstruction that the patient had in a previous operation, we needed to attach an apical cuff on posterior apex, insert the inflow cannula with a large curve, and shift the skin insertion site laterally to the left. We assessed the angle between the cardiac longitudinal axis and the inflow cannula using computed tomography. The patient did not complain of any subjective symptoms of heart failure. Although Nipro extra-corporeal left ventricular assist device installation after left ventricular reconstruction has several difficulties historically, we have experienced a successful case.

Early and mid-term outcomes of left ventricular assist device implantation and future prospects

OBJECTIVES

Although implantable left ventricular assist device use as a bridge to heart transplantation is increasing, its permanent use as destination therapy is not permitted in Japan. This retrospective review assessed early and mid-term outcomes of implantable continuous-flow left ventricular assist device compared with extracorporeal pulsatile-flow left ventricular assist device implantation. Issues regarding left ventricular assist device as destination therapy are discussed.

METHODS

From January 2009 to September 2013, 72 patients underwent left ventricular assist device implantation at our institute. Forty patients were supported by extracorporeal pulsatile-flow left ventricular assist devices (ex-VAD group) and 32 patients with implantable continuous-flow left ventricular assist devices (im-VAD group).

RESULTS

The median duration of ventricular assist device support was 563 days. The actuarial survival rates at 1 and 3 years were 92.3 and 79.2 % in the ex-VAD group and 96.4 and 72.3 % in the im-VAD group, respectively. Approximately 50 % of patients in both groups developed cerebrovascular complications within 1 year postoperatively. Six months post-implantation, almost 90 % of the ex-VAD group patients suffered exit-site infection compared with about 50 % in the im-VAD group. Readmission rate was 1.74 per patient-year; major causes were driveline exit-site infection (52 %) and cerebrovascular complication (14 %).

CONCLUSIONS

Early and mid-term outcomes were satisfactory after both extracorporeal pulsatile-flow left ventricular assist device and implantable continuous-flow left ventricular assist device implantation, although a considerable level of postoperative complications was observed. More data after left ventricular assist device surgery are needed to enable its consideration as a destination therapy option in Japan.

Application of a search algorithm using stochastic behaviors to autonomous control of a ventricular assist device

A ventricular assist device (VAD) is a device with mechanical pumps implanted adjacent to the patient's native heart to support the blood flow. Mechanical circulatory support using VADs has been an essential therapeutic tool for patients with severe heart failure waiting for a heart transplant in clinical site. Adaptive control of VADs that automatically adjust the pump output with changes in a patient state is one of the important approaches for enhanced therapeutic efficacy, prevention of complications and quality of life improvement. However adaptively controlling a VAD in the realistic situation would be difficult because it is necessary to model the whole including the VAD and the cardiovascular dynamics. To solve this problem, we propose an application of attractor selection algorithm using stochastic behavior to a VAD control system. In this study, we sought to investigate whether this proposed method can be used to adaptively control of a VAD in the simple case of a continuous flow VAD. The flow rate control algorithm was constructed on the basis of a stochastically searching algorithm as one example of application. The validity of the constructed control algorithm was examined in a mock circuit. As a result, in response to a low-flow state with the different causes, the flow rate of the pump reached a target value with self adaptive behavior without designing the detailed control rule based on the experience or the model of the control target.

Development of a flow rate monitoring method for the wearable ventricular assist device driver

Our research institute has been working on the development of a compact wearable drive unit for an extracorporeal ventricular assist device (VAD) with a pneumatically driven pump. A method for checking the pump blood flow on the side of the drive unit without modifying the existing blood pump and impairing the portability of it will be useful. In this study, to calculate the pump flow rate indirectly from measuring the flow rate of the driving air of the VAD air chamber, we conducted experiments using a mock circuit to investigate the correlation between the air flow rate and the pump flow rate as well as its accuracy and error factors. The pump flow rate was measured using an ultrasonic flow meter at the inflow and outflow tube, and the air flow was measured using a thermal mass flow meter at the driveline. Similarity in the instantaneous waveform was confirmed between the air flow rate in the driveline and the pump flow rate. Some limitations of this technique were indicated by consideration of the error factors. A significant correlation was found between the average pump flow rate in the ejecting direction and the average air flow rate in the ejecting direction (R2 = 0.704-0.856), and the air flow rate in the filling direction (R2 = 0.947-0.971). It was demonstrated that the average pump flow rate was estimated exactly in a wide range of drive conditions using the air flow of the filling phase.

Midterm outcome of implantable left ventricular assist devices as a bridge to transplantation: Single-center experience in Japan

BACKGROUND

Two implantable continuous-flow left ventricular assist devices (LVADs), DuraHeart (Terumo Heart, Ann Arbor, MI, USA) and EVAHEART (Sun Medical, Nagano, Japan), were approved in Japan in April 2011. We analyzed the midterm outcome of patients implanted with these implantable LVADs at the University of Tokyo Hospital.

METHODS AND RESULTS

A total of 31 patients who underwent implantation of LVADs (10 DuraHeart, 21 EVAHEART) as a bridge to transplantation at our institution between April 2011 and August 2013 were retrospectively reviewed. All patients were followed up through December 2013. Seven patients underwent conversions from NIPRO paracorporeal LVAD (Nipro, Osaka, Japan) to an implantable LVAD. The mean observation period was 483±239 days (41.0 patient years). Eight patients were transplanted and one patient showed functional recovery with subsequent LVAD explantation. Four patients died due to cerebrovascular accident, empyema, or device malfunction due to pump thrombosis after cerebral bleeding. Kaplan-Meier analysis revealed 6-, 12-, and 24-month survival rates of 93%, 86%, and 86%, respectively. The rates of freedom from cerebrovascular accidents and device-related infections at 1 year after LVAD implantation were 65% and 36%, respectively. Twenty-nine patients were discharged home after LVAD implantation. During the period of this study, there were 59 readmissions (53 urgent, 6 elective) among 22 patients (76%). The overall and urgent readmission rates were 1.66 and 1.49 per patient year, respectively. The common reason for readmission was device-related infection (31%), followed by cerebrovascular accidents (17%). The total out-of-hospital time after the primary discharge was 90%.

CONCLUSIONS

Our midterm survival rate after LVAD implantation is satisfactory. However, patients undergoing LVAD support were often readmitted with adverse events.

Results of the prospective multicenter Japanese bridge to transplant study with a continuous-flow left ventricular assist device

Continuous-flow left ventricular assist devices (LVADs) are becoming the standard of care for patients with refractory end-stage heart failure. We present the outcomes of patients enrolled in a prospective multicenter clinical study in Japan using the HeartMate II continuous-flow LVAD for bridge to transplantation. The study evaluated 6 inotrope-dependent heart failure patients failing on medical management (3 males and 3 females, age 44.7 ± 15.8 years, BSA 1.58 ± 0.17 m(2)) implanted with the HMII LVAD at 5 Japanese centers. Functional status, adverse events and outcomes were determined for the first 6 months with follow-up at 2 years. After implant, functional improvement was evident in 6-min walk distance which increased from 268 ± 92 m at baseline to 399 ± 105 m at 6 months, and 100% of patients were in NYHA class I or II at 6 months compared to 0% at baseline. Adverse events included localized non-device-related infection (4/6), arrhythmias (3/6) and percutaneous lead infection (1/6). There were no re-thoracotomies for bleeding and no strokes or pump replacements. All patients were alive at 6 months and all were transplanted after 1.96-3.58 years of LVAD support. The results in Japan of the HMII LVAD for BTT are consistent with results from the US pivotal clinical trial. The expanded use of this technology to Japanese heart failure patients is appropriate.

An overview of mechanical circulatory support in children

OBJECTIVE

For children with severe heart failure in whom medical management has failed, mechanical circulatory support in the form of either extracorporeal membrane oxygenation or ventricular assist device represents life-sustaining therapy. This review provides an overview of these two modalities, including a discussion of indications, contraindications, timing, and device selection, as part of the Pediatric Cardiac Intensive Care Society/Extracorporeal Life Support Organization Joint Statement on Mechanical Circulatory Support. DATA SOURCES, STUDY SELECTION, DATA EXTRACTION: PubMed was searched using the following terms: ECMO, extracorporeal membrane oxygenation, ventricular assist device, VAD, and pediatric. Case reports, single-center series, multicenter studies, and registry reports were reviewed.

CONCLUSIONS

The two technologies have unique advantages and disadvantages and may be considered complementary devices, although they are frequently used in sequence. Either modality may be used as bridge-to-transplant or bridge-to-recovery, and the choice of device and device timing is influenced by the acuity of illness, comorbidities, potential for recovery, and anticipated duration of support.

Risk analysis and detection of thrombosis by measurement of electrical resistivity of blood

Monitoring of thrombogenic process is very important in ventricular assistance devices (VADs) used as temporary or permanent measures in patients with advanced heart failure. Currently, there is a lack of a system which can perform a real-time monitoring of thrombogenic activity. Electrical signals vary according to the change in concentration of coagulation factors as well as the distribution of blood cells, and thus have potential to detect the thrombogenic process in an early stage. In the present work, we have made an assessment of an instrumentation system exploiting the electrical properties of blood. The experiments were conducted using bovine blood. Electrical resistance tomography with eight-electrode sensor was used to monitor the spatio-temporal change in electrical resistivity of blood in thrombogenic and non-thrombogenic condition. Under non-thrombogenic condition, the resistivity was uniform across the cross-section and average resistivity monotonically decreased with time before remaining almost flat. In contrary, under thrombogenic condition, there was non-uniform distribution across the cross-section, and average resistivity fluctuated with time.

Destination therapy: the new gold standard treatment for heart failure patients with left ventricular assist devices

Heart failure continues to be a growing health problem, eluding large-scale improvement and treatment. Cardiac transplantation has been the gold standard treatment with high post-transplant survival rates and relatively good quality of life. However, there has been an extreme shortage of organ donations, limiting transplants to only a very small portion of patients with the condition. This led to a growing interest in alternative options for the increasing population of patients who are waitlisted or ineligible for transplantation. In recent years, ventricular assist device (VAD) technologies have advanced from pulsatile blood pumps to continuous-flow pumps that have demonstrated unprecedented post-implantation survival rates. The HeartMate II, the only commercially available, continuous flow left ventricular assist device (LVAD) in the United States and Europe, has been implanted in over 10,000 patients worldwide, setting a benchmark for biomedical modalities of advanced heart failure treatment. Thanks to the successes of contemporary LVADs, patients are able to enjoy a better lifestyle, with a significantly prolonged life span and the ability to regularly partake in physical activities. In this new biomedical generation, the usage of LVADs has begun to expand towards the treatment for a wider range of heart conditions, including earlier stages of heart failure. In fact, LVAD implantations have surpassed the number of transplants taken place annually. An increasing number of patients are considering the permanent, circulatory support with an LVAD, namely destination therapy, as a promising option for treating heart failure.

Outcome of patients with cardiac sarcoidosis undergoing cardiac transplantation--single-center retrospective analysis

BACKGROUND

Controversy exists whether heart transplantation (HTx) is an appropriate treatment option for patients with cardiac sarcoidosis due to its potential recurrence and multi-organ involvement. Recent data from the United Network for Organ Sharing dataset suggest that the clinical outcome of cardiac sarcoidosis patients is equivalent or even better than that of the general HTx population.

METHODS

We retrospectively reviewed the clinical course of 14 patients with cardiac sarcoidosis among a total of 825 patients who underwent HTx at Columbia University Medical Center between 1997 and 2010. Post-transplant survival of patients with sarcoidosis was compared with that of non-sarcoidosis patients.

RESULTS

More than half of cardiac sarcoidosis patients were initially diagnosed after HTx by tissue analysis of the explanted heart. While only 2/14 cases showed recurrence of cardiac sarcoidosis, the clinical outcome of sarcoid patients showed a trend toward higher mortality than that of non-sarcoidosis patients following HTx (1- and 5-year survival, 78.5 versus 87.2%, 52.4 versus 76.2%, respectively, p=0.09).

CONCLUSIONS

Although this is a single-center, retrospective analysis of a small number of cardiac sarcoidosis patients who underwent HTx, a concerning trend toward a higher mortality of patients with cardiac sarcoidosis was noted. A careful candidate selection in patients with known cardiac sarcoidosis should be discussed.