Left ventricular assist device: a functional comparison with heart transplantation

Nanomaterials for Cardiac Tissue Engineering

End stage heart failure is a major cause of death in the US. At present, organ transplant and left-ventricular assist devices remain the only viable treatments for these patients. Cardiac tissue engineering presents the possibility of a new option. Nanomaterials such as gold nanorods (AuNRs) and carbon nanotubes (CNTs) present unique properties that are beneficial for cardiac tissue engineering approaches. In particular, these nanomaterials can modulate electrical conductivity, hardness, and roughness of bulk materials to improve tissue functionality. Moreover, they can deliver bioactive cargo to affect cell phenotypes. This review covers recent advances in the use of nanomaterials for cardiac tissue engineering.

Left ventricular assist device: exercise capacity evolution and rehabilitation added value

BACKGROUND

With more than 15,000 implanted patients worldwide and a survival rate of 80% at 1-year and 59% at 5-years, left ventricular assist device (LVAD) implantation has become an interesting strategy in the management of heart failure patients who are resistant to other kinds of treatment. There are limited data in the literature on the change over time of exercise capacity in LVAD patients, as well as limited knowledge about the beneficial effects that rehabilitation might have on these patients. Therefore, the aim of our study was to evaluate the evolution of exercise capacity on a cohort of patients implanted with the same device (HeartWare^©) and to analyse the potential impact of rehabilitation.

METHODS

Sixty-two patients implanted with a LVAD between June 2011 and June 2015 were screened. Exercise capacity was evaluated by cardiopulmonary exercise testing at 6 weeks, 6 and 12 months after implantation.

RESULTS

We have observed significant differences in the exercise capacity and evolution between the trained and non-trained patients. Some of the trained patients nearly normalised their exercise capacity at the end of the rehabilitation programme.

CONCLUSIONS

Exercise capacity of patient implanted with a HeartWare^© LVAD increased in the early period after implantation. Rehabilitation allowed implanted patients to have a significantly better evolution compared to non-rehabilitated patients.

New therapy, new challenges: The effects of long-term continuous flow left ventricular assist device on inflammation

Surgically implanted continuous flow left ventricular assist devices (CF-LVADs) are currently used in patients with end-stage heart failure (HF). However, CF-LVAD therapy introduces a new set of complications and adverse events in these patients. Major adverse events with the CF-LVAD include right heart failure, vascular dysfunction, stroke, hepatic failure, and multi-organ failure, complications that may have inflammation as a common etiology. Our aim was to review the current evidence showing a relationship between these adverse events and elevated levels of inflammatory biomarkers in CF-LVAD recipients.

Singularity now: using the ventricular assist device as a model for future human-robotic physiology

In our 21^st century world, human-robotic interactions are far more complicated than Asimov predicted in 1942. The future of human-robotic interactions includes human-robotic machine hybrids with an integrated physiology, working together to achieve an enhanced level of baseline human physiological performance. This achievement can be described as a biological Singularity. I argue that this time of Singularity cannot be met by current biological technologies, and that human-robotic physiology must be integrated for the Singularity to occur. In order to conquer the challenges we face regarding human-robotic physiology, we first need to identify a working model in today's world. Once identified, this model can form the basis for the study, creation, expansion, and optimization of human-robotic hybrid physiology. In this paper, I present and defend the line of argument that currently this kind of model (proposed to be named "IshBot") can best be studied in ventricular assist devices - VAD.

Left ventricular assist devices: a kidney's perspective

The left ventricular assist device (LVAD) has become an established treatment option for patients with refractory heart failure. Many of these patients experience chronic kidney disease (CKD) due to chronic cardiorenal syndrome type II, which is often alleviated quickly following LVAD implantation. Nevertheless, reversibility of CKD remains difficult to predict. Interestingly, initial recovery of GFR appears to be transient, being followed by gradual but significant late decline. Nevertheless, GFR often remains elevated compared to preimplant status. Larger GFR increases are followed by a proportionally larger late decline. Several explanations for this gradual decline in renal function after LVAD therapy have been proposed, yet a definitive answer remains elusive. Mortality predictors of LVAD implantation are the occurrence of either postimplantation acute kidney injury (AKI) or preimplant CKD. However, patient outcomes continue to improve as LVAD therapy becomes more widespread, and adverse events including AKI appear to decline. In light of a growing destination therapy population, it is important to understand the cumulative effects of long-term LVAD support on kidney function. Additional research and passage of time are required to further unravel the intricate relationships between the LVAD and the kidney.

Left ventricular assist device for end-stage heart failure: results of the first LVAD destination program in the Netherlands

Purpose

Mechanical circulatory support with a continuous-flow left ventricular assist device (LVAD) may be a valuable treatment in end-stage heart failure patients for an extended period of time. The purpose of this study was to evaluate the safety and efficacy of implantation of a continuous-flow LVAD in end-stage heart failure patients within the first destination program in the Netherlands.

Methods

A third-generation LVAD was implanted in 16 heart failure patients (age 61 ± 8; 81 % male; left ventricular ejection fraction 20 ± 6 %) as destination therapy. All patients were ineligible for heart transplant. At baseline, 3 and 6 months, New York Heart Association (NYHA) functional class, quality-of-life and exercise capacity were assessed. Clinical adverse events were registered.

Results

Survival at 30 days and 6 months was 88 and 75 %, respectively. In the postoperative phase, 6 (38 %) patients required continuous veno-venous haemofiltration for renal failure and 2 (13 %) patients required extracorporeal membrane oxygenation because of severe right ventricular failure. During follow-up, NYHA functional class and quality-of-life improved from 3.7 ± 0.1 to 2.3 ± 0.1 and 57 ± 5 to 23 ± 3 at 6 months (P < 0.001), respectively. The 6 min walking distance improved from 168 ± 42 m to 291 ± 29 m at 6 months (P = 0.001).

Conclusion

Continuous-flow LVAD therapy is a promising treatment for patients with end-stage heart failure ineligible for heart transplant.

Biomarkers in mechanical circulatory support

Heart failure is a complex multifaceted syndrome occurring as a result of impaired cardiac function. Understanding the neurohormonal, inflammatory and molecular pathways involved in the pathophysiology of this syndrome has led to the development of effective and widely used pharmacological treatments. Despite this, mortality and hospitalization rates associated with this condition remain high. The natural course of this illness is usually progressive, often leading inexorably to end stage heart failure, for which orthotopic heart transplant is a treatment option but one with limited resource. In the past decade, mechanical circulatory support has emerged as a potential therapy for certain patients with advanced heart failure. This article reviews the published data regarding biomarkers in the setting of mechanical circulatory support, and highlights areas of ongoing work and potential future areas of interest.

Effect of left ventricular assist device implantation and heart transplantation on habitual physical activity and quality of life

The present study defined the short- and long-term effects of left ventricular assist device (LVAD) implantation and heart transplantation (HT) on physical activity and quality of life (QoL). Forty patients (LVAD, n = 14; HT, n = 12; and heart failure [HF], n = 14) and 14 matched healthy subjects were assessed for physical activity, energy expenditure, and QoL. The LVAD and HT groups were assessed postoperatively at 4 to 6 weeks (baseline) and 3, 6, and 12 months. At baseline, LVAD, HT, and HF patients demonstrated low physical activity, reaching only 15%, 28%, and 51% of that of healthy subjects (1,603 ± 302 vs 3,036 ± 439 vs 5,490 ± 1,058 vs 10,756 ± 568 steps/day, respectively, p <0.01). This was associated with reduced energy expenditure and increased sedentary time (p <0.01). Baseline QoL was not different among LVAD, HT, and HF groups (p = 0.44). LVAD implantation and HT significantly increased daily physical activity by 60% and 52%, respectively, from baseline to 3 months (p <0.05), but the level of activity remained unchanged at 3, 6, and 12 months. The QoL improved from baseline to 3 months in LVAD implantation and HT groups (p <0.01) but remained unchanged afterward. At any time point, HT demonstrated higher activity level than LVAD implantation (p <0.05), and this was associated with better QoL. In contrast, physical activity and QoL decreased at 12 months in patients with HF (p <0.05). In conclusion, patients in LVAD and HT patients demonstrate improved physical activity and QoL within the first 3 months after surgery, but physical activity and QoL remain unchanged afterward and well below that of healthy subjects. Strategies targeting low levels of physical activity should now be explored to improve recovery of these patients.

Treatment options in end-stage heart failure: where to go from here?

Chronic heart failure is a major healthcare problem associated with high morbidity and mortality. Despite significant progress in treatment strategies, the prognosis of heart failure patients remains poor. The golden standard treatment for heart failure is heart transplantation after failure of medical therapy, surgery and/or cardiac resynchronisation therapy. In order to improve patients’ outcome and quality of life, new emerging treatment modalities are currently being investigated, including mechanical cardiac support devices, of which the left ventricular assist device is the most promising treatment option. Structured care for heart failure patients according to the most recent international heart failure guidelines may further contribute to optimal decision-making. This article will review the conventional and novel treatment modalities of heart failure.

Functional and haemodynamic recovery after implantation of continuous-flow left ventricular assist devices in comparison with pulsatile left ventricular assist devices in patients with end-stage heart failure

AIMS

Caused by ageing of the population, better survival from ischaemic heart disease, and improved treatment of chronic heart disease, the incidence of heart failure has increased enormously. Worldwide, left ventricular assist devices (LVADs) are increasingly being used as a bridge or alternative to heart transplantation. In this study, we investigated whether there is difference in functional and haemodynamic recovery after implantation of pulsatile and continuous-flow pumps.

METHODS AND RESULTS

We compared laboratory and echocardiographic data and exercise performance in patients with end-stage heart failure, before and 3 months after implantation of pulsatile and continuous-flow LVADs. A significant improvement in all laboratory parameters after implantation of both types of LVADs was seen, as well as a significant decrease in heart rate and LV dimensions, indicating better haemodynamics and cardiac recompensation. This improvement was better for the pulsatile device, probably due to higher plasma levels and higher LV dimensions before implantation. Exercise capacity strongly improved: 3 months after implantation of pulsatile and continuous-flow LVADs, peak VO(2) was 20.2 ± 4.8 vs. 18.3 ± 4.8 mL/kg/min (P = 0.09) (53 ± 12 vs. 49 ± 11% of predicted for age and gender) (P = 0.28).

CONCLUSION

Pulsatile and continuous-flow LVADs result in extensive haemodynamic recovery and exercise performance compatible with daily life activities. Exercise performance with continuous-flow LVADs is equal to that with pulsatile devices. This, in combination with improved survival of the newer devices, allows its use as an alternative to heart transplantation in selected patients.

Benefits of physical training on exercise capacity, inspiratory muscle function, and quality of life in patients with ventricular assist devices long-term postimplantation

BACKGROUND

Capacity to exercise may not be fully restored in patients with heart failure even in the long term after ventricular assist device (VAD) implantation. The benefits of exercise training in patients with VAD are unknown.

DESIGN AND METHODS

Fifteen patients, aged 38.3 ± 15.9 years, bridged to heart transplantation with left ventricular assist device or biventricular assist device were randomized at a ratio of 2 : 1 to a training group (TG, n = 10) or a control group (n = 5), 6.3 ± 4 months after implantation. Both the groups were advised to walk 30–45 min/day. TG also underwent moderate-intensity aerobic exercise using a bike or treadmill for 45 min, three to five times a week, combined with high-intensity inspiratory muscle training using a computer-designed software to respiratory exhaustion, two to three times a week for 10 weeks. The patients were tested using cardiopulmonary exercise testing, 6-min walk test, spirometry and electronic pressure manometer for inspiratory muscle strength (Pimax) and endurance (sustained Pimax) measurement. Quality of life was assessed with the Minnesota Living with Heart Failure questionnaire.

RESULTS

TG improved peak oxygen consumption (19.3 ± 4.5 vs. 16.8 ± 3.7 ml/kg per min, P = 0.008) and VO2 at ventilatory threshold (15.1 ± 4.2 vs. 12 ± 5.6 ml/kg per min, P = 0.01), whereas the ventilation/carbon dioxide slope decreased (35.9 ± 5.6 vs. 40 ± 6.5, P = 0.009). The 6-min walk test distance increased (527 ± 76 vs. 462 ± 88 m, P = 0.005) and quality of life was improved (38.2 ± 11.6 vs. 48.9 ± 12.8, P = 0.005), as well as Pimax (131.8 ± 33 vs. 95.5 ± 28cmH2O, P = 0.005), sustained Pimax (484 ± 195 vs. 340 ± 193cmH2O/s/103, P = 0.005), and inspiratory lung capacity (2.4 ± 0.9 vs. 1.7 ± 0.7 L, P = 0.008) were improved. No significant changes were noted in the control group.

CONCLUSION

Our findings indicate that exercise training may improve the functional status of VAD recipients even at a later period after implantation and thus, may have additional importance in cases of destination therapy.

End-of-life decision making and implementation in recipients of a destination left ventricular assist device

BACKGROUND

The use of left ventricular assist devices (LVADs) as destination therapy (DT) is increasing and has proven beneficial in prolonging survival and improving quality of life in select patients with end-stage heart failure. Nonetheless, end-of-life (EOL) issues are inevitable and how to approach them underreported.

METHODS

Our DT data registry was queried for eligible patients, defined as those individuals who actively participated in EOL decision making. The process from early EOL discussion to palliation and death was reviewed. We recorded the causes leading to EOL discussion, time from EOL decision to withdrawal and from withdrawal to death, and location. Primary caregivers were surveyed to qualify their experience and identify themes relevant to this process.

RESULTS

Between 1999 and 2009, 92 DT LVADs were implanted in 69 patients. Twenty patients qualified for inclusion (mean length of support: 833 days). A decrease in quality of life from new/worsening comorbidities usually prompted EOL discussion. Eleven patients died at home, 8 in the hospital and 1 in a nursing home. Time from EOL decision to LVAD withdrawal ranged from <1 day to 2 weeks and from withdrawal until death was <20 minutes in all cases. Palliative care was provided to all patients. Ongoing assistance from the healthcare team facilitated closure and ensured comfort at EOL.

CONCLUSIONS

With expanding indications and improved technology, more DT LVADs will be implanted and for longer durations, and more patients will face EOL issues. A multidisciplinary team approach with protocols involving DT patients and their families in EOL decision making allows for continuity of care and ensures dignity and comfort at EOL.

Health-related quality of life and exercise tolerance in recipients of heart transplants and left ventricular assist devices: a prospective, comparative study

BACKGROUND

The aim of this study was to evaluate and compare health-related quality of life (HRQoL) and physical exercise tolerance in patients after heart transplantation (HTx) or implantation of a left ventricular assist device (LVAD).

METHODS

A prospective, comparative design was used to characterize changes over time in HRQoL (SF-36) and exercise tolerance in patients after HTx (n = 54) and during LVAD support (n = 36). Nine LVAD patients were lost for follow-up. The majority of patients in both groups were male (97%); the LVAD cohort tended to be younger (p = 0.06).

RESULTS

HRQoL improved significantly in HTx patients in the SF-36 physical (p = 0.02), but not in the psychosocial (p = 0.27) component score during follow-up. In the LVAD group, HRQoL showed improvements for both the SF-36 physical and psychosocial component scores (both p = 0.04). Between-group comparisons revealed better HRQoL for the HTx cohort than the LVAD cohort for 2 of 8 SF-36 subscales. Age-, gender- and body mass index (BMI)-adjusted exercise tolerance (workload; VO(2max)) showed significant improvements for both HTx (p = 0.01) and LVAD (p = 0.01) patients. Adjusted maximum oxygen consumption was higher for HTx patients (p = 0.05) relative to LVAD patients at 8 ± 1 months after implant.

CONCLUSION

HRQoL and exercise capacity increased in both groups over the time-course of the study. After adjusting for relevant variables, HTx patients showed a higher exercise tolerance compared with the LVAD group during follow-up. Thus, future large-scale intervention studies should emphasize the specific needs of these patient cohorts.

The current status of heart transplantation and the development of "artificial heart systems"

BACKGROUND

In view of the major technical advances in ventricular assist devices (VAD) in recent years, the authors discuss the question whether these "artificial hearts" are still no more than a temporary measure for patients awaiting heart transplantation (HTx), or whether they can already be used as an independent form of long-term treatment.

METHODS

Statistics from Eurotransplant regarding heart transplantations and transplant waiting lists in Germany are presented. Technical developments in cardiac support systems, the variation in results depending on the indication, and the findings with respect to quality of life are all discussed on the basis of a selective review of the literature and the authors' own clinical experience.

RESULTS

The waiting list for heart transplantation in Germany has grown to a record size of nearly 800 patients, while fewer than 400 hearts are transplanted each year. Technical advances have improved outcomes in VAD therapy, but the outcome depends on the patient's preoperative condition. The physical performance of patients who have received VAD is comparable to that of HTx patients; nonetheless, HTx patients have a better quality of life.

CONCLUSIONS

Chronic VAD therapy has become a clinical reality. Because of the greater number of patients awaiting HTx, many will not receive their transplants in time. When the decision to treat with VAD is made early, it can be used as an alternative form of treatment with a comparable one-year survival (>75%).

Left ventricular assist device: a functional comparison with heart transplantation

BACKGROUND

A growing number of patients with end-stage heart failure undergo implantation of ventricular assist devices as a bridge to heart transplantation.

OBJECTIVES

In this study we investigated whether functional and haemodynamic recovery after implantation is sufficient to warrant the use of them as long-term alternative to heart transplantation.

METHODS

We compared peak VO(2) of a group of patients three months after implantation of a ventricular assist device and three months after heart transplantation. Furthermore, we analysed the degree of haemodynamic recovery, by comparing plasma levels of BNP and creatinine before and after implantation of the device.

RESULTS

After implantation of a ventricular assist device, exercise capacity improved considerably; three months after implantation peak VO(2) was 20.0+/-4.9 ml/kg/min (52% of predicted for age and gender). After heart transplantation exercise capacity improved even further; 24.0+/-3.9 ml/ kg/min (62% of predicted for age and gender) (p<0.001). In the three months after implantation, BNP plasma levels decreased from 570+/-307 pmol/l to 31+/-25 pmol/l and creatinine levels decreased from 191+/-82 mumol/l to 82+/-25 mumol/l, indicating significant unloading of the ventricles and haemodynamic recovery.

CONCLUSION

With regard to functional and haemodynamic recovery, the effect of implantation of a ventricular assist device is sufficient to justify its use as an alternative to heart transplantation. (Neth Heart J 2008;16:41-6.).