Advances in mechanical circulatory support: Year in review

The Role of Artificial Intelligence and Machine Learning in the Prediction of Right Heart Failure after Left Ventricular Assist Device Implantation: A Comprehensive Review

One of the most challenging and prevalent side effects of LVAD implantation is that of right heart failure (RHF) that may develop afterwards. The purpose of this study is to review and highlight recent advances in the uses of AI in evaluating RHF after LVAD implantation. The available literature was scanned using certain key words (artificial intelligence, machine learning, left ventricular assist device, prediction of right heart failure after LVAD) was scanned within Pubmed, Web of Science, and Google Scholar databases. Conventional risk scoring systems were also summarized, with their pros and cons being included in the results section of this study in order to provide a useful contrast with AI-based models. There are certain interesting and innovative ML approaches towards RHF prediction among the studies reviewed as well as more straightforward approaches that identified certain important predictive clinical parameters. Despite their accomplishments, the resulting AUC scores were far from ideal for these methods to be considered fully sufficient. The reasons for this include the low number of studies, standardized data availability, and lack of prospective studies. Another topic briefly discussed in this study is that relating to the ethical and legal considerations of using AI-based systems in healthcare. In the end, we believe that it would be beneficial for clinicians to not ignore these developments despite the current research indicating more time is needed for AI-based prediction models to achieve a better performance.

Durable Continuous-Flow Mechanical Circulatory Support: State of the Art

Implantable mechanical circulatory support (MCS) systems for ventricular assist device (VAD) therapy have emerged as an important strategy due to a shortage of donor organs for heart transplantation. A growing number of patients are receiving permanent assist devices, while fewer are undergoing heart transplantation (Htx). Continuous-flow (CF) pumps, as devices that can be permanently implanted, show promise for the treatment of both young and old patients with heart failure (HF). Further improvement of these devices will decrease adverse events, enable pulse modulation of continuous blood flow, and improve automatic remote monitoring. Ease of use for patients could also be improved. We herein report on the current state of the art regarding implantable CF pumps for use as MCS systems in the treatment of advanced refractory HF.

Right ventricle failure in patients treated with left ventricular assist device

This review article aim to highlight the right ventricular function peri left ventricular assist device implantation, and to assess the incidence, physiopathology, predictors, management and prognosis, of right ventricular failure post-implant.

Calculation of the ALMA Risk of Right Ventricular Failure After Left Ventricular Assist Device Implantation

Right ventricular failure after continuous-flow left ventricular assist device (LVAD) implantation is still an unsolved issue and remains a life-threatening event for patients. We undertook this study to determine predictors of the patients who are candidates for isolated LVAD therapy as opposed to biventricular support (BVAD). We reviewed demographic, echocardiographic, hemodynamic, and laboratory variables for 258 patients who underwent both isolated LVAD implantation and unplanned BVAD because of early right ventricular failure after LVAD insertion, between 2006 and 2017 (LVAD = 170 and BVAD = 88). The final study patients were randomly divided into derivation (79.8%, n = 206) and validation (20.1%, n = 52) cohorts. Fifty-seven preoperative risk factors were compared between patients who were successfully managed with an LVAD and those who required a BVAD. Nineteen variables demonstrated statistical significance on univariable analysis. Multivariable logistic regression analysis identified destination therapy (odds ratio [OR] 2.0 [1.7-3.9], p = 0.003), a pulmonary artery pulsatility index <2 (OR 3.3 [1.7-6.1], p = 0.001), a right ventricle/left ventricle end-diastolic diameter ratio >0.75 (OR 2.7 [1.5-5.5], p = 0.001), an right ventricle stroke work index <300 mm Hg/ml/m (OR 4.3 [2.5-7.3], p < 0.001), and a United Network for Organ Sharing modified Model for End-Stage Liver Disease Excluding INR score >17 (OR 3.5 [1.9-6.9], p < 0.001) as the major predictors of the need for BVAD. Using these data, we propose a simple risk calculator to determine the suitability of patients for isolated LVAD support in the era of continuous-flow mechanical circulatory support devices.

A Proof-of-Concept Demonstration for a Novel Soft Ventricular Assist Device

Patients treated by current ventricular assist devices (VADs) suffer from various post implantation complications including gastrointestinal bleeding and arteriovenous malformation. These issues are related to intrinsically mismatch of generated flow by VADs and the physiological flow. In addition, the common primary drawback of available VADs is excessive surgical dissection during implantation, which limits these devices to less morbid patients. We investigated an alternative soft VAD (SVAD) system that generates physiological flow, and designed to be implanted using minimally invasive surgery by leveraging soft materials. A soft VAD (which is an application of intraventricular balloon pump) is developed by utilizing a polyurethane balloon, which generates pulsatile flow by displacing volume within the left ventricle during its inflation and deflation phases. Our results show that the SVAD system generates an average ejection fraction of 50.18 ± 1.52% (n = 6 ± SD) in explanted porcine hearts. Since the SVAD is implanted via the apex of the heart, only a minithoracotomy should be required for implantation. Our results suggest that the SVAD system has the performance characteristics that could potentially make it useful for patients in acute and/or chronic heart failure, thus serving as a bridge-to-transplantation or bridge-to-recovery.

First series of mechanical circulatory support in non-compaction cardiomyopathy: Is LVAD implantation a safe alternative?

BACKGROUND

Left ventricular non-compaction (LVNC) is a rare cardiac disorder characterized by prominent trabeculae and deep recesses of the ventricular myocardium. Patients with LVNC may develop severe congestive heart failure refractory to medical therapy. However, heart transplantation is strongly limited due to donor organ shortage. Thus mechanical circulatory support by left ventricular assist devices (LVADs) is a promising alternative. Nevertheless, hypertrabeculation and proarrhythmogenic potential in LVNC might represent important hurdles for success of LVAD therapy in these patients.

METHODS AND RESULTS

We retrospectively analyzed the data of a total of 5 patients (3 HVAD, Heartware®; 2 HeartMate II, Thoratec®) with LVNC who underwent LVAD implantation in our institution between 2010 and 2014. Mean follow-up time was 86.5weeks. 30-day survival was 100% without major intrahospital complications. During follow-up, 3 patients developed pump thrombosis requiring pump replacement. Arrhythmias were not detected during follow-up as assessed by ICD interrogation.

CONCLUSIONS

LVAD implantation in LVNC can be performed with low intrahospital complication rates. However, we observed a high incidence of pump thrombosis during follow-up, possibly related to thromboembolic predisposition by the underlying LVNC. Therefore, careful management of anticoagulation appears to be critical in these patients.

Minimally invasive ventricular assist device surgery

The use of mechanical circulatory support to treat patients with congestive heart failure has grown enormously, recently surpassing the number of annual heart transplants worldwide. The current generation of left ventricular assist devices (LVADs), as compared with older devices, is characterized by improved technologies and reduced size. The result is that minimally invasive surgery is now possible for the implantation, explantation, and exchange of LVADs. Minimally invasive procedures improve surgical outcome; for example, they lower the rates of operative complications (such as bleeding or wound infection). The miniaturization of LVADs will continue, so that minimally invasive techniques will be used for most implantations in the future. In this article, we summarize and describe minimally invasive state-of-the-art implantation techniques, with a focus on the most common LVAD systems in adults.

Mechanical circulatory support in advanced heart failure: single-center experience

BACKGROUND

Currently, ventricular assist device (VAD) or total artificial heart (TAH) mechanical support provides an effective treatment of unstable patients with advanced heart failure. We report our single-center experience with mechanical circulatory support therapy.

METHODS

From March 2002 to December 2012, 107 adult patients (mean age, 56.8 ± 9.9 y; range, 31-76 y) were primarly supported on temporary or long-term VAD or TAH support as treatment for refractory heart failure at our institution. Temporary extracorporeal radial VAD support (group A) was established in 49 patients (45.7%), and long-term paracorporeal and intracorporeal VAD or TAH (group B) in 58 patients (54.2%). Left ventricular (LVAD) support was established in 55 patients (51.4%; n = 33, Heartmate II; n = 6, Heartmate I XVE; n = 4, Heartware HVAD; and n = 12, Centrimag) and biventricular (BVAD/TAH) support (group B) in 28 patients (26.1%; n = 10, Thoratec paracorporeal; n = 2, Heartware HVAD, n = 1, Thoratec implantable; n = 1, Syncardia TAH; and n = 14, Centrimag). The temporary Centrimag was the only device adopted as isolated right ventricular (RVAD) support, and it was inserted in 24 patients (22.4%).

RESULTS

In group A, overall mean support time was 10.2 ± 6.6 days (range, 3-43 d). In group B, LVAD mean support time was 357 ± 352.3 days (range, 1-902 d) and BVAD/TAH support time was 98 ± 82.6 days (range, 8-832 d). In group A, the overall success rate was 55.1% (27 patients). In group B, LVAD overall success rate was 74.4% (32 patients) and BVAD/TAH success rate was 50% (7 patients). Overall heart transplantation rate for both groups was 27.1% (n = 2, group A; n = 27, group B). Overall 1-year and 5-year survivals after heart transplantation were 72.4% (n = 21) and 58.6% (n = 17), respectively.

CONCLUSIONS

Mechanical circulatory support is an effective strategy even in cases of end-stage heart failure according to our experience. Further improvement of VAD and TAH technologies may support their adoption as an encouraging alternative to heart transplantation in the near future.

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.

Initial clinical experience with the HeartWare left ventricular assist system: a single-center report

BACKGROUND

The HeartWare ventricular assist device (HVAD) system (HeartWare International Inc, Framingham, MA) is a new centrifugal continuous-flow ventricular assist device. The aim of the present study is to review our institutional experience with this novel device.

METHODS

We reviewed the files of 50 patients (39 men, 11 women) with a mean age of 50.6 ± 11.8 years (range, 19 to 70 years) who underwent HVAD implantation between July 2009 and November 2011. Two patients underwent HeartWare BIVAD implantation. The underlying heart diseases were end-stage ischemic heart disease (n = 12), acute myocardial infarction (n = 9), dilated cardiomyopathy (n = 27) and acute myocarditis (n = 2). Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profiles were level 1 (n = 11), 2 (n = 5), 3 (n = 10), and 4 (n = 24).

RESULTS

After a cumulative support duration of 11,086 days, Kaplan-Meier analysis revealed a survival of 82.0%, 77.9%, 75.5%, at 1, 12, and 24 months, respectively. Causes of early death were right heart failure (n = 4), multiorgan failure (n = 2), septic shock (n = 2), and major neurologic complications (n = 4). One late death occurred due to a right heart failure. Comparison between patients operated on in cardiogenic shock (INTERMACS 1 and 2) and patients who underwent elective HVAD implantation (INTERMACS 3 and 4) revealed a survival of 61.5% and 44.1% for the INTERMACS 1 and 2 group and 90.3% and 87.1% for the INTERMACS 3 and 4 group at 1 and 12 months, respectively (odds ratio, 4.67; p = 0.003). One patient was weaned from the system after 2 years. Eleven patients (22%) were successfully bridged to transplantation. Mean time to transplantation was 209 days (range, 72 to 427 days). Posttransplant survival at the 1-year follow-up was 90.9% (11 patients).

CONCLUSIONS

Our experience with HVAD shows satisfying results with an excellent posttransplantation survival. Moreover, the stratified survival based on the level of preoperative stability shows better outcomes in patients undergoing elective HVAD implantation.

Pediatric Ventricular Assist Devices: The Future (as of 2011)

In the last decade, there have been enormous advances in the field of pediatric-specific mechanical circulatory support. In the past, small children requiring bridge to transplant or recovery were limited to extracorporeal membrane oxygenation. Now, in various stages of development, there are several devices that offer the promise of the same quality of support enjoyed by older teenagers and adolescents, with the potential to substantially reduce transplant waiting list mortality and optimize transplant outcomes. Advances have been driven by both industry and, for the first time, by funding from the US National Institutes of Health.