Mechanical Circulatory Support in the Treatment of Advanced Heart Failure

Ventricular Arrhythmias and Sudden Cardiac Death in Left Ventricular Assist Device Patients Without Implantable Cardioverter Defibrillators

Patients with left ventricular assist devices (LVAD) can develop sustained ventricular arrhythmias (VA). The history and presentation of VA in implantable cardioverter defibrillator (ICD)-naive patients with LVAD is not well described in the literature and the risks/benefits of ICD implantation are unknown. This single-center retrospective cohort study included patients >18 years old who did not have an ICD during LVAD implantation from 2010 to 2022. The primary outcome was VA event rate per 100 patient-years. Two hundred thirty-seven patients underwent LVAD implantation and we identified 46 (19.4%) ICD naive patients. The etiology of heart failure in most patients was nonischemic cardiomyopathy (67.4%). Of all patients, only five were found to have documented VA. Only two episodes of VA occurred in the ambulatory setting. The estimated index VA rate was 5.89 events per 100 patient-years in our entire ICD-naive LVAD population. In the ambulatory ICD-naive population, the estimated VA rate was 2.42 events per 100 patient-years with no associated mortality. The rate of index VA in ICD-naive patients was below thresholds associated with benefits from ICD insertion. No ambulatory mortality from VA was seen and VA was well tolerated by the LVAD population. Perioperative VA in this population is associated with high mortality.

Artificial Muscles and Soft Robotic Devices for Treatment of End-Stage Heart Failure

Medical soft robotics constitutes a rapidly developing field in the treatment of cardiovascular diseases, with a promising future for millions of patients suffering from heart failure worldwide. Herein, the present state and future direction of artificial muscle-based soft robotic biomedical devices in supporting the inotropic function of the heart are reviewed, focusing on the emerging electrothermally artificial heart muscles (AHMs). Artificial muscle powered soft robotic devices can mimic the action of complex biological systems such as heart compression and twisting. These artificial muscles possess the ability to undergo complex deformations, aiding cardiac function while maintaining a limited weight and use of space. Two very promising candidates for artificial muscles are electrothermally actuated AHMs and biohybrid actuators using living cells or tissue embedded with artificial structures. Electrothermally actuated AHMs have demonstrated superior force generation while creating the prospect for fully soft robotic actuated ventricular assist devices. This review will critically analyze the limitations of currently available devices and discuss opportunities and directions for future research. Last, the properties of the cardiac muscle are reviewed and compared with those of different materials suitable for mechanical cardiac compression.

Perioperative Outcomes in Patients With Failing Single-Ventricle Physiology Undergoing Ventricular Assist Device Placement: A Single Institutional Experience

OBJECTIVE

To address the current lack of specified data existing regarding the perioperative characteristics and outcomes in a novel patient population, which may bridge the current understanding of how patient characteristics and perioperative management may influence the postoperative hospital course before cardiac transplantation.

DESIGN

A retrospective electronic chart review included all patients with failing single- ventricle (SV) physiology receiving ventricular assist device (VAD) support at a high-volume pediatric VAD center between April 5, 2010, and December 1, 2020, using institution-based electronic medical records for retrospective analysis.

SETTING

At a single pediatric hospital.

PARTICIPANTS

Fourteen pediatric patients with failing SV physiology receiving ventricular assist device therapy (SVAD).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Preoperative, intraoperative, and postoperative patient demographic and medical data were obtained from prior inpatient progress notes, laboratory values, anesthetic records, cardiac catheterization reports, echocardiography reports, and postoperative surgical notes entered during inpatient encounters at the time of SVAD placement. Between April 5, 2010, and December 1, 2020, 16 VAD device implants supported 14 pediatric patients with failing SV physiology. Most patients presented with a preoperative diagnosis of hypoplastic left heart syndrome (N = 9, 64.3%). A total of 6 patients expired on VAD therapy (43%), 7 (50%) survived to receive a cardiac transplant, and 1 patient currently remains on device therapy.

CONCLUSION

Although our institutional approach represents a single perspective, we anticipate that our experience institutional experience may prove helpful to others caring for peditric patients with single ventricle physiology undergoing ventricular assist device placement and promote collaborative efforts to improve their care.

Advancements in left ventricular assist devices to prevent pump thrombosis and blood coagulopathy

Mechanical circulatory support (MCS) devices, such as left ventricular assist devices (LVADs) are very useful in improving outcomes in patients with advanced-stage heart failure. Despite recent advances in LVAD development, pump thrombosis is one of the most severe adverse events caused by LVADs. The contact of blood with artificial materials of LVAD pumps and cannulas triggers the coagulation cascade. Heat spots, for example, produced by mechanical bearings are often subjected to thrombus build-up when low-flow situations impair washout and thus the necessary cooling does not happen. The formation of thrombus in an LVAD may compromise its function, causing a drop in flow and pumping power leading to failure of the LVAD, if left unattended. If a clot becomes dislodged and circulates in the bloodstream, it may disturb the flow or occlude the blood vessels in vital organs and cause internal damage that could be fatal, for example, ischemic stroke. That is why patients with LVADs are on anti-coagulant medication. However, the anti-coagulants can cause a set of issues for the patient-an example of gastrointestinal (GI) bleeding is given in illustration. On account of this, these devices are only used as a last resort in clinical practice. It is, therefore, necessary to develop devices with better mechanics of blood flow, performance and hemocompatibility. This paper discusses the development of LVADs through landmark clinical trials in detail and describes the evolution of device design to reduce the risk of pump thrombosis and achieve better hemocompatibility. Whilst driveline infection, right heart failure and arrhythmias have been recognised as LVAD-related complications, this paper focuses on complications related to pump thrombosis, especially blood coagulopathy in detail and potential strategies to mitigate this complication. Furthermore, it also discusses the LVAD implantation techniques and their anatomical challenges.

Self-care in Adults With a Retro-auricular Left Ventricular Assist Device: An Interpretive Description

Having a retro-auricular left ventricular assist device (LVAD) requires patients to learn specific self-care behaviors, with a considerable burden; the present study aimed at exploring and describing the experience of self-care in this population. An Interpretive Description was conducted, informing the analysis with the Middle-Range Theory of Self-care of Chronic Illness. A purposeful sample of ten people with a retro-auricular LVAD participated in in-depth, semi-structured interviews. Four themes were identified: Innovations and Limitations in Daily Life, Problems Detection, Response to Problems, and Learning Process. All of these were deeply influenced by a cross-cutting theme: Support System. People with a retro-auricular LVAD have self-care needs different from those of people with heart failure or with the abdominal version of the device, and there is a great need for targeted intervention that could be developed in consideration of our findings.

Fully Elman Neural Network: A Novel Deep Recurrent Neural Network Optimized by an Improved Harris Hawks Algorithm for Classification of Pulmonary Arterial Wedge Pressure

Heart failure (HF) is one of the most prevalent life-threatening cardiovascular diseases in which 6.5 million people are suffering in the USA and more than 23 million worldwide. Mechanical circulatory support of HF patients can be achieved by implanting a left ventricular assist device (LVAD) into HF patients as a bridge to transplant, recovery or destination therapy and can be controlled by measurement of normal and abnormal pulmonary arterial wedge pressure (PAWP). While there are no commercial long-term implantable pressure sensors to measure PAWP, real-time non-invasive estimation of abnormal and normal PAWP becomes vital. In this work, first an improved Harris Hawks optimizer algorithm called HHO+ is presented and tested on 24 unimodal and multimodal benchmark functions. Second, a novel fully Elman neural network (FENN) is proposed to improve the classification performance. Finally, four novel 18-layer deep learning methods of convolutional neural networks (CNNs) with multi-layer perceptron (CNN-MLP), CNN with Elman neural networks (CNN-ENN), CNN with fully Elman neural networks (CNN-FENN), and CNN with fully Elman neural networks optimized by HHO+ algorithm (CNN-FENN-HHO+) for classification of abnormal and normal PAWP using estimated HVAD pump flow were developed and compared. The estimated pump flow was derived by a non-invasive method embedded into the commercial HVAD controller. The proposed methods are evaluated on an imbalanced clinical dataset using 5-fold cross-validation. The proposed CNN-FENN-HHO+ method outperforms the proposed CNN-MLP, CNN-ENN and CNN-FENN methods and improved the classification performance metrics across 5-fold cross-validation with an average sensitivity of 79%, accuracy of 78% and specificity of 76%. The proposed methods can reduce the likelihood of hazardous events like pulmonary congestion and ventricular suction for HF patients and notify identified abnormal cases to the hospital, clinician and cardiologist for emergency action, which can diminish the mortality rate of patients with HF.

Multidisciplinary management of pleural infection after ventricular assist device implantation

Background

Postsurgical pleural infection is a life-threatening complication after implantation of artificial devices such as ventricular assist devices (VADs). The treatment can be challenging and the evidence in the literature is very limited. Here we report our multidisciplinary approach of the management of pleural infection after VAD implantation.

Methods

Between March 2014 and December 2019, 33 patients developed postoperative pleural infection after VAD implantation and underwent thoracic surgical intervention at our institution. All patients were prospectively enrolled in this analysis. Data were retrospectively analyzed. Primary outcome was the 90-day mortality rate. Length of ICU stay related to pleural infection, chest tube duration, re-thoracotomy rate and length of ventilatory support represented secondary outcomes.

Results

The 90-day mortality rate was 6% (2 patients). The mean ICU stay related to the pleural infection was 6 days (2-24 days). Video-assisted thoracoscopic surgery (VATS) was performed in all patients. Conversion to thoracotomy was necessary in 12 cases. Decortication and parietal pleurectomy in addition to hematoma and empyema removal was performed in all patients. Due to diffuse bleeding, packing of the thoracic cavity with temporary thoracic closure was necessary in 10 patients. Depacking was performed after a mean of 3 days (3-7 days). Recurrent empyema or bleeding after definitive chest closure was not observed. Lung resection was performed in 3 patients.

Conclusions

Thoracic surgical management of pleural infection in patients after VAD implantation is challenging and complicated due to the inevitable anticoagulative therapy. A perioperative multidisciplinary management which includes the early involvement of thoracic surgical expertise helps to improve survival in this very complex patient cohort.

Pediatric ventricular assist device registries: update and perspectives in the era of miniaturized continuous-flow pumps

The success of ventricular assist devices (VADs) in the treatment of end-stage heart failure in the adult population has led to industrial innovation in VAD design, focusing on miniaturization and the reduction of complications. A byproduct of these innovations was that newer generation devices could have clinical applications in the pediatric population. Over the last decade, VAD usage in the pediatric population has increased dramatically, and the newer generation continuous flow (CF) devices have begun to supplant the older, pulsatile flow (PF) devices, formerly the sole option for ventricular assist in the pediatric population. However, despite the increase in VAD implants in the pediatric population, patient numbers remain low, and the need to share data between pediatric VAD centers has become that much more important for the continued growth of VAD programs worldwide. The creation of pediatric VAD registries, such as the Pediatric Registry for Mechanical Circulatory Support (PediMACS), the European Registry for Patients with Mechanical Circulatory Support (EUROMACS) and the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) has enabled the collection of aggregate data from VAD centers worldwide, and provides a valuable resource for clinicians and programs, as more and more pediatric heart failure patients are considered candidates for VAD therapy.

Overview of Options for Mechanical Circulatory Support

Mechanical circulatory support is used widely in acute setting of myocardial infarction, myocarditis, and cardiogenic shock as well as in chronic scenarios with advanced end-stage heart failure. Different algorithmic approaches can help the clinician decide the type of support required in a high morbidity and mortality setting. It is paramount to emphasize the need for a multidisciplinary approach to make steadfast decisions in the acute settings of cardiogenic shock.

A Sensorless Control System for an Implantable Heart Pump Using a Real-Time Deep Convolutional Neural Network

Left ventricular assist devices (LVADs) are mechanical pumps, which can be used to support heart failure (HF) patients as bridge to transplant and destination therapy. To automatically adjust the LVAD speed, a physiological control system needs to be designed to respond to variations of patient hemodynamics across a variety of clinical scenarios. These control systems require pressure feedback signals from the cardiovascular system. However, there are no suitable long-term implantable sensors available. In this study, a novel real-time deep convolutional neural network (CNN) for estimation of preload based on the LVAD flow was proposed. A new sensorless adaptive physiological control system for an LVAD pump was developed using the full dynamic form of model free adaptive control (FFDL-MFAC) and the proposed preload estimator to maintain the patient conditions in safe physiological ranges. The CNN model for preload estimation was trained and evaluated through 10-fold cross validation on 100 different patient conditions and the proposed sensorless control system was assessed on a new testing set of 30 different patient conditions across six different patient scenarios. The proposed preload estimator was extremely accurate with a correlation coefficient of 0.97, root mean squared error of 0.84 mmHg, reproducibility coefficient of 1.56 mmHg, coefficient of variation of 14.44%, and bias of 0.29 mmHg for the testing dataset. The results also indicate that the proposed sensorless physiological controller works similarly to the preload-based physiological control system for LVAD using measured preload to prevent ventricular suction and pulmonary congestion. This study shows that the LVADs can respond appropriately to changing patient states and physiological demands without the need for additional pressure or flow measurements.

Mechanical circulatory support as a bridge to candidacy in adults with transposition of the great arteries and a systemic right ventricle

OBJECTIVES

Clinical experience with continuous flow ventricular assist devices (VADs) in patients with transposition of the great arteries (TGA) including dextro-TGA and congenitally corrected TGA is rare, and indications as well as potential benefits or specific hurdles remain unclear. Therefore, our goal was to report on our experience regarding VAD therapy in adult patients with TGA as a bridge to candidacy.

METHODS

We performed a single-centre retrospective study of all adult patients with TGA with systemic right ventricular failure who had continuous flow VAD implants between 2010 and 2018. Study end points were all causes of death, major cardiac and cerebrovascular adverse events or pump thrombosis. Follow-up continued until the time of the heart transplant.

RESULTS

A total of 6 patients (4 men) had a continuous flow VAD implanted in the context of a failing systemic right ventricle (dextro-TGA after the Mustard procedure: n = 3; congenitally corrected TGA: n = 3). Demographics: mean age 32 ± 5.7 years; median Interagency Registry for Mechanically Assisted Circulatory Support: level II (range 1-4), mean pulmonary artery 48 ± 13 mmHg, mean pulmonary vascular resistance 5.6 ± 3.5 Wood units. Postoperative data: intensive care unit stay: 16 ± 9.7 days; in-hospital survival: 100%; no early VAD-related complications occurred. Mean follow-up: 33 ± 18 months; persistent left-side paresis: n = 1; minor (non-disabling) stroke: n = 2. Post-VAD pulmonary artery: 19 ± 3.4 mmHg; P < 0.005; post-VAD pulmonary resistance: 2.2 ± 0.55 Wood units; P = 0.066. Four patients had heart transplants after a mean waiting time of 30 months after the VAD was implanted; 2 patients are still on the waiting list (waiting time: 52 and 24 months).

CONCLUSIONS

Continuous flow VAD therapy is a feasible therapeutic option in adult patients with TGA and a failing systemic right ventricle as a bridge to candidacy and a bridge to a heart transplant.

Factors associated with body image among patients with an implanted left ventricular assist device

BACKGROUND

Among Left Ventricular Assist Device (LVAD) implanted patients, body image modifications might occur.

OBJECTIVES

To explore the associations between sexual functioning, confidence in LVAD technology, personal wellbeing, and body image.

METHODS

The cross-sectional study included 30 conveniently recruited LVAD implanted patients who completed Body Image Scale, sexual functioning, confidence in LVAD technology, and Personal Wellbeing Index questionnaires. The associations between the research variables were examined with multiple regression analyses.

RESULTS

The mean age of the participants was 63 (SD=10), 90% were men. The mean scores were: sexual functioning - 2.43 (SD=1.20, range 1-5); confidence in LVAD technology - 2.63 (SD=1.04, range 1-5); Well-Being Index - 6.61 (SD=1.53, range 0-10); and body image - 14.5 (SD=4.17, range 5-20). Sexual functioning (p<.01) and LVAD technology confidence (p=.04) significantly predicted body image.

CONCLUSIONS

Healthcare professionals should be aware of challenges regarding body image faced by LVAD implanted patients and to address related factors.

Current perspectives on mechanical circulatory support

Mechanical circulatory support gained a significant value in the armamentarium of heart failure therapy because of the increased awareness of the prevalence of heart failure and the tremendous advances in the field of mechanical circulatory support during the last decades. Current device technologies already complement a heart transplant as the gold standard of treatment for patients with end-stage heart failure refractory to conservative medical therapy. This article reviews important aspects of mechanical circulatory support therapy and focuses on currently debated issues.

Permanent Implantable Cardiac Support Systems

BACKGROUND

Nearly 1000 permanent ventricular assist devices (VADs) are implanted in patients with severe congestive heart failure in Germany each year. VADs are miniaturized centrifugal pumps that generate continuous blood flow; they are powered and controlled through a cable that passes through the skin. Para- corporeal systems are only rarely implanted, usually in children.

METHODS

In this selective review of the literature, including guidelines and registry data, we discuss the indications, therapeutic effects, and complications of permanently implantable cardiac support systems.

RESULTS

The optimal time for VAD implantation cannot be precisely defined. A comparative assessment of the various available systems is not possible, as no randomized trials have been performed on this topic. Registry data indicate that 69% to 81% of patients survive one year after VAD implantation, which is signifi- cantly better than the natural course of (conservatively treated) severe congestive heart failure. The distance patients are able to walk is 129 to 220 m longer at six months, depending on the system implanted. Scores on the EQ-5D health status questionnaire are 28 to 37 points better at six months. The potential severe compli- cations include infection, right-heart failure, hemorrhage, pump thrombosis, stroke, and death.

CONCLUSION

A VAD system can be implanted as an alternative to cardiac transplan- tation or as a bridging treatment until the patient can be listed for transplantation and receive the transplant. Because of the organ s , only a minority of VAD patients ever receive a transplant.

Comparing short-term outcome after implantation of the HeartWare® HVAD® and the Abbott® HeartMate 3®

AIMS

Centrifugal continuous flow pumps are currently the state of the art in left ventricular assist device therapy. This study was conducted to compare the results after implantation of the HVAD® and the HeartMate 3®.

METHODS AND RESULTS

We retrospectively analysed preoperative and post-operative patient data of all 106 patients, who received a HeartMate 3 (HM3) at our centre between 2014 and 2018. A total of 392 patients receiving a sintered HVAD® served as controls. Patient matching was performed for age, sex, Interagency Registry for Mechanically Assisted Circulatory Support level at the time of implant, perioperative right heart failure, and implantation strategy, that is, bridge to transplant or destination therapy, as well as preoperative renal function, that is, as indicated by serum creatinine levels. A total of 79 matched pairs could be identified. During a median follow-up of 15.3 months (range: 0-30 months), 23 (29.1%) and 19 (24.1%) patients died in the HVAD and HM3 groups, respectively, with a hazard ratio for mortality of 0.84 [95% confidence interval (CI): 0.46-1.54; P = 0.568]. Freedom from cerebrovascular events did not differ significantly between study groups, with a hazard ratio of 0.57 (95% CI: 0.23-1.45; P = 0.241). The risk of driveline infection was significantly lower in the HM3 (n = 33) than in the HVAD (n = 55) group (hazard ratio = 0.54; 95% CI: 0.35-0.84; P = 0.006). Eight HVAD, but no HM3, patients developed a pump thrombosis during follow-up (P = 0.148).

CONCLUSIONS

Performance of both currently used centrifugal left ventricular assist device systems is comparable in terms of short-term patient survival and freedom from cerebrovascular events. In our single-centre experience, HM3 patients less frequently develop driveline infections and no pump thrombosis, which requires further evaluation.

Randomized trial of a left ventricular assist device as destination therapy versus guideline-directed medical therapy in patients with advanced heart failure. Rationale and design of the SWEdish evaluation of left Ventricular Assist Device (SweVAD) trial

AIMS

Patients with advanced heart failure (AdHF) who are ineligible for heart transplantation (HTx) can become candidates for treatment with a left ventricular assist device (LVAD) in some countries, but not others. This reflects the lack of a systematic analysis of the usefulness of LVAD systems in this context, and of their benefits, limitations and cost-effectiveness. The SWEdish evaluation of left Ventricular Assist Device (SweVAD) study is a Phase IV, prospective, 1:1 randomized, non-blinded, multicentre trial that will examine the impact of assignment to mechanical circulatory support with guideline-directed LVAD destination therapy (GD-LVAD-DT) using the HeartMate 3 (HM3) continuous flow pump vs. guideline-directed medical therapy (GDMT) on survival in a population of AdHF patients ineligible for HTx.

METHODS

A total of 80 patients will be recruited to SweVAD at the seven university hospitals in Sweden. The study population will comprise patients with AdHF (New York Heart Association class IIIB-IV, INTERMACS profile 2-6) who display signs of poor prognosis despite GDMT and who are not considered eligible for HTx. Participants will be followed for 2 years or until death occurs. Other endpoints will be determined by blinded adjudication. Patients who remain on study-assigned interventions beyond 2 years will be asked to continue follow-up for outcomes and adverse events for up to 5 years.

CONCLUSION

The SweVAD study will compare survival, medium-term benefits, costs and potential hazards between GD-LVAD-DT and GDMT and will provide a valuable reference point to guide destination therapy strategies for patients with AdHF ineligible for HTx.

Left Ventricular Assist Devices (LVADS): History, Clinical Application and Complications

Congestive heart failure is a major cause of morbidity and mortality as well as a major health care cost in the developed world. Despite the introduction of highly effective heart failure medical therapies and simple devices such as cardiac resynchronization therapy that reduce mortality, improve cardiac function and quality of life, there remains a large number of patients who do not respond to these therapies or whose heart failure progresses despite optimal therapy. For these patients, cardiac transplantation is an option but is limited by donor availability as well as co-morbidities which may limit survival post-transplant. For these patients, left ventricular assist devices (LVADs) offer an alternative that can improve survival as well as exercise tolerance and quality of life. These devices have continued to improve as technology has improved with substantially improved durability of the devices and fewer post-implant complications. Pump thrombosis, stroke, gastrointestinal bleeding and arrhythmias post-implant have become less common with the newest devices, making destination therapy where ventricular assist device are implanted permanently in patients with advanced heart failure, a reality and an appropriate option for many patients. This may offer an opportunity for long term survival in many patients. As the first of the totally implantable devices are introduced and go to clinical trials, LVADs may be introduced that may truly be alternatives to cardiac transplantation in selected patients. Post-implant right ventricular failure remains a significant complication and better ways to identify patients at risk as well as to manage this complication must be developed.