Outflow Graft Tamponade: An Underrecognized Cause of Obstruction

BACKGROUND

Left ventricular assist device (LVAD) outflow graft obstruction can result in severe clinical deterioration. Underlying mechanisms may vary depending on the location. Outflow graft tamponade due to external compression can be under recognized. Management of this complication varies across institutions and a uniform approach has yet to be elucidated.

OBJECTIVES

Report a single center experience with outflow graft tamponade in patients with LVAD with the purpose of developing an optimal algorithm for the diagnosis and treatment of LVAD-related outflow graft tamponade.

METHODS AND RESULTS

Retrospective chart review between July 2011 and July 2020. A total of 351 LVADs were implanted at our center, with outflow graft tamponade identified in 26 patients with LVAD. Fourteen (53.8%) had HeartMate II™, 8 (30.8%) had HeartMate3™ and 4 (15.4%) had HeartWare™. Individuals presented with heart failure symptoms, an audible precordial murmur and LVAD alarms after a median duration of 862 days of support (IQR 327 - 1455). Of the 26 patients, 15 (57.7%) underwent mini thoracotomy with outflow graft relief, 4 had percutaneous balloon dilatation and stenting, 2 were bridged directly to transplant and 1 had a pump exchange. No intervention was made on the remaining due to mild symptoms (n = 4).

CONCLUSIONS

Conclusions: Outflow graft tamponade is a form outflow graft obstruction with a variable presentation that can result in significant hemodynamic compromise. It is amenable to both surgical and percutaneous interventions that restore LVAD function.

Contemporary outcomes of continuous-flow left ventricular assist devices-a systematic review

Background

End stage heart failure is a major cause of morbidity and mortality, and its prevalence is expected to rise with the ageing population. For suitable patients, orthotopic heart transplantation remains the gold standard therapy, however, a paucity of donor organs has led to the development of left ventricular assist devices (LVAD). These devices can be utilized as either a bridge-to-transplant (BTT) or as an alternative to heart transplantation. While these devices can prolong life and improve quality of life, they are associated with a significant number of adverse events. We aim to systematically review the literature to quantify survival and the incidence of adverse events following implantation of continuous-flow LVADs (cf-LVAD).

Methods

A systematic review was performed to determine outcomes following implantation of a cf-LVAD. Primary outcomes were survival and frequency of adverse events (such as bleeding, infection, thrombosis, stroke and right ventricular failure). Secondary outcomes included quality of life and assessment of functional status.

Results

Sixty-three studies reported clinical outcomes of 9,280 patients. Survival after cf-LVAD varied between studies. Industry-funded trials generally reported better overall survival than the single- and multi-center case series, which showed significant variation. The largest registry report documented twelve, twenty-four and forty-eight-month survival rates of 82%, 72% and 57% respectively. The most commonly reported adverse events were gastrointestinal bleeding (GIB), device-related infection, neurological events and right heart failure (RHF). Bleeding, RHF and infection were the most frequent complications experienced by those supported with cf-LVAD, occurring in up to 35%, 40% and 55% of patients, respectively. Quality of life as measured using the Kansas City Cardiomyopathy Questionnaire (KCCQ) and functional status as measured with the 6-minute walk test (6MWT) improved after cf-LVAD implantation with no decline evident two years after implantation.

Conclusions

The paucity of donor hearts has led to the development of left-ventricular assist devices as a BTT or as a destination therapy (DT). Outcomes after cf-LVAD implantation are excellent, with short-term survival comparable to heart transplantation, but long-term survival remains limited due to the incidence of post-implantation adverse events. Despite these complications, quality of life and functional status improve significantly post-implantation and remain improved over the long-term. This study demonstrates the potential benefits of cf-LVAD therapy whilst also identifying adverse events as an area of increased morbidity and mortality.

Conventional and alternative sites for left ventricular assist device inflow and outflow cannula placement

Left ventricular assist device (LVAD) therapy is a well accepted and effective strategy to treat advanced heart failure. The miniaturized third-generation centrifugal pumps HeartWare HVAD (Medtronic, Dublin, Ireland) and HeartMate 3 (Abbott, Illinois, USA) are the two most commonly implanted systems in the contemporary era. Their design has allowed clinicians to pioneer several alternate and less invasive implantation techniques to tackle a broad spectrum of clinical scenarios. A brief review and discussion of alternative surgical techniques for both inflow and outflow cannula insertion, in the contemporary LVAD surgery era, are herein reported.

Sex differences in outcomes following less-invasive left ventricular assist device implantation

Background

Worse outcomes in women compared to men undergoing left ventricular assist device (LVAD) implantation remain an underestimated problem in heart failure (HF) patients. With device miniaturization, less-invasive LVAD implantation techniques have gained relevance, but their impact on outcomes in women is unknown. This study investigates sex-related differences in patients undergoing LVAD implantation through less-invasive procedures.

Methods

This retrospective single-center cohort study included patients who underwent isolated LVAD implantation between 2011 and 2018 through less-invasive techniques. Propensity score matching (PSM) was utilized to balance preoperative heterogeneity. Primary endpoint was two-year survival, and secondary endpoints included long-term survival, surgical outcomes and postoperative adverse events.

Results

Baseline analysis of 191 patients (females 18.3%) showed differences in terms of age [female (median, 52; IQR, 47-61); male (median, 58.5; IQR, 49-66); P=0.005], underlying diagnosis (P<0.001), INTERMACS profile (P=0.009), history of previous cardiac surgery (P=0.049) and preoperative creatinine values [female (median, 110; IQR, 71-146); male (median, 126; IQR, 9-168); P=0.049]. Over a follow-up of 460.68 patient-years, Kaplan-Meyer analysis showed better survival in females (P=0.027) and a similar probability of cardiac transplantation (P=0.288). After PSM, females showed higher needs for intraoperative fresh frozen plasma (P=0.044) and platelets (P=0.001) but comparable postoperative outcomes. No sex-related differences were noticed regarding two-year outcomes, long-term survival and adverse events. LVAD-related infections remained the most common complication with males experiencing more pump infections than women (P=0.050).

Conclusions

Patients receiving less-invasive LVAD implantation do not show significant sex-related differences in short and long-term outcomes and survival. Prospective studies are needed to evaluate the role of less-invasive techniques in reducing sex-based disparities after LVAD implantation.

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.

Lateral Thoracotomy for Ventricular Assist Device Implantation: A Meta-Analysis of Literature

The use of lateral thoracotomy (LT) for implanting left ventricular assist devices (LVADs) is worldwide increasing, although the available evidence for its positive effects compared with conventional sternotomy (CS) is limited. This systematic review and meta-analysis analyzes the outcomes of LT compared with CS in patients undergoing implantation of a centrifugal continuous-flow LVAD. Four databases and 1,053 publications were screened until December 2019. Articles including patients undergoing implantation of a centrifugal continuous-flow LVAD through LT were included. A meta-analysis to compare LT and CS was performed to summarize evidences from studies including both LT and CS patients extracted from the same population. Primary outcome measure was in-hospital or 30-day mortality. Eight studies reporting on 730 patients undergoing LVAD implantation through LT (n = 242) or CS (n = 488) were included in the meta-analysis. Left thoracotomy showed lower in-hospital/30-day mortality (odds ratio [OR]: 0.520, 95% confidence interval [CI]: 0.27-0.99, p = 0.050), shorter intensive care unit (ICU) stay (mean difference [MD]: 3.29, CI: 1.76-4.82, p < 0.001), lower incidence of severe right heart failure (OR: 0.41; CI: 0.19-0.87, p = 0.020) and postoperative right ventricular assist device (RVAD) implantation (OR: 0.27, CI: 0.10-0.76, p = 0.010), fewer perioperative transfusions (MD: 0.75, CI: 0.36-1.14, p < 0.001), and lower incidence of renal failure (OR: 0.45, CI: 0.20-1.01, p = 0.050) and device-related infections (OR: 0.45, CI: 0.20-1.01, p = 0.050), respectively. This meta-analysis demonstrates that implantation of a centrifugal continuous-flow LVAD system via LT benefits from higher short-term survival, less right heart failure, lower postoperative RVAD need, shorter ICU stay, less transfusions, lower risk of device-related infections and kidney failure. Prospective studies are needed for further proof.

Ventricular assist devices implantation: surgical assessment and technical strategies

Along with the worldwide increase in continuous left ventricular assist device (LVAD) strategy adoption, more and more patients with demanding anatomical and clinical features are currently referred to heart failure (HF) departments for treatment. Thus surgeons have to deal, technically, with re-entry due to previous cardiac surgery procedures, porcelain aorta, peripheral vascular arterial disease, concomitant valvular or septal disease, biventricular failure. New surgical techniques and surgical tools have been developed to offer acceptable postoperative outcomes to all mechanical circulatory support recipients. Several less invasive and/or thoracotomic approaches for surgery combined with various LVAD inflow and outflow graft alternative anastomotic sites for system placement have been reported and described to solve complex clinical scenarios. Surgical techniques have been upgraded with further technical tips to preserve the native anatomy in case of re-entry for heart transplantation, myocardial recovery or device explant. The current continuous-flow miniaturized and intrapericardial devices provide versatility and technical advantages. However, the surgical planning requires a careful multidisciplinary evaluation which must be driven by a dedicated and well-trained Heart Failure team. Biventricular assist device (BVAD) implantation by adoption of the newer radial pumps might be a challenge. However, the results are encouraging thus remaining a valid option. This paper reviews and summarizes LVAD preoperative assessment and current surgical techniques for implantation.

Expert Consensus Paper: Lateral Thoracotomy for Centrifugal Ventricular Assist Device Implant

BACKGROUND

The increasing prevalence of heart failure has led to the expanded use of left ventricle assist devices (VADs) for end-stage heart failure patients worldwide. Technological improvements witnessed the development of miniaturized VADs and their implantation through less traumatic non-full sternotomy approaches using a lateral thoracotomy (LT). Although adoption of the LT approach is steadily growing, a lack of consensus remains regarding patient selection, details of the surgical technique, and perioperative management. Furthermore, the current literature does not offer prospective randomized studies or evidence-based guidelines for LT-VAD implantation.

METHODS

A worldwide group of LT-VAD experts was convened to discuss these key topics openly. After a PubMed search and review with all authors, a consensus was reached and an expert consensus paper on LT-VAD implantation was developed.

RESULTS

This document aims to guide clinicians in the selection of patients suitable for LT approaches and preoperative optimization. Details of operative techniques are described, with an overview of hemisternotomy and bilateral thoracotomy approaches. A review of the best surgical practices for placement of the pump, inflow cannula, and outflow graft provides advice on the best surgical strategies to avoid device malpositioning while optimizing VAD function. Experts' opinions on cardiopulmonary bypass, postoperative management, and approaches for pump exchange and explant are presented. This review also emphasizes the critical need for multidisciplinary teams and specific training.

CONCLUSIONS

This expert consensus review provides a compact guide to LT for VAD implantation, from patient selection through intraoperative tips and postoperative management.

Minimally invasive left ventricular assist device implantation: optimizing device design for this approach

Introduction: The global heart failure (HF) burden is expected to increase due to aging populations, increasing number of end-stage HF patients and adverse lifestyle changes. Mechanical circulatory support (MCS) devices such as left ventricular assist devices (LVADs) have become a promising treatment option for short-term and long-term circulatory support of end-stage HF patients.Areas covered: Recent developments in MCS technology have been focused on miniaturization leading to the development of minimally invasive surgical procedures for LVAD implantation. This helps overcome possible postoperative complications such as major incisions and poor outcomes due to infections, right heart failure, and bleeding. This article discusses clinical and technological developments in the field of minimally invasive procedures for LVAD implantation.Expert opinion: Most patients might benefit from minimally invasive LVAD implantation performed through a limited left lateral thoracotomy associated with an upper hemisternotomy or a right anterior thoracotomy. The thoracotomy approach can also be considered in case of pump exchange or pump explant. The success of these techniques is mainly based on the optimization of LVAD pump design, inflow cannula insertion, and outflow graft as well as driveline exit sites. The future direction of the LVAD field is likely to include less-invasive approaches and smartificial technologies.

2019 EACTS Expert Consensus on long-term mechanical circulatory support

Long-term mechanical circulatory support (LT-MCS) is an important treatment modality for patients with severe heart failure. Different devices are available, and many-sometimes contradictory-observations regarding patient selection, surgical techniques, perioperative management and follow-up have been published. With the growing expertise in this field, the European Association for Cardio-Thoracic Surgery (EACTS) recognized a need for a structured multidisciplinary consensus about the approach to patients with LT-MCS. However, the evidence published so far is insufficient to allow for generation of meaningful guidelines complying with EACTS requirements. Instead, the EACTS presents an expert opinion in the LT-MCS field. This expert opinion addresses patient evaluation and preoperative optimization as well as management of cardiac and non-cardiac comorbidities. Further, extensive operative implantation techniques are summarized and evaluated by leading experts, depending on both patient characteristics and device selection. The faculty recognized that postoperative management is multidisciplinary and includes aspects of intensive care unit stay, rehabilitation, ambulatory care, myocardial recovery and end-of-life care and mirrored this fact in this paper. Additionally, the opinions of experts on diagnosis and management of adverse events including bleeding, cerebrovascular accidents and device malfunction are presented. In this expert consensus, the evidence for the complete management from patient selection to end-of-life care is carefully reviewed with the aim of guiding clinicians in optimizing management of patients considered for or supported by an LT-MCS device.

Left ventricular assist device (LVAD) program in Chile: first successful experience in South America

Background

The need to have a variety of tools to deal with end-stage heart failure (ES-HF), along with the limited heart transplantation availability encouraged us to create a pilot Left ventricular assist device (LVAD) program in a public health care system hospital in Chile.

Methods

A retrospective analysis of the first nine patients of an ongoing LVAD program initiated on August 2013 was performed, completing an average of 30 months of follow-up. The most important events regarding to morbidity and mortality are described.

Results

Nine patients with ES-HF underwent LVAD implantation surgery; one of them died 23 days after surgery and another died after 11 months. One patient successfully underwent heart transplantation after 16 months of HeartWare ventricular assist device (HVAD) support; the other six patients remain in the program and have an average follow-up of 846 days at the time of this study (range, 23-1,481 days). The survival rate at 6, 12 and 18 months follow-up was 89%, 78% and 78% respectively.

Conclusions

This new pioneering LVAD program in Chile has been successful and now constitutes a vital adjunct to all who work in heart transplantation and ES-HF programs. It offers an effective therapeutic alternative when there is a severe donor shortage, in cases of atypical blood types, emergencies, exceptional cases with contraindication for heart transplantation or when there is important donor-receiver size mismatch.

Effects of pump speed changes on exercise capacity in patients supported with a left ventricular assist device-an overview

The implantation of left ventricular assist devices (LVAD) has been established as a successful treatment for terminal heart failure (HF) for many years. Patient benefits include significantly improved survival, as well as improved quality of life. However, peak exercise capacity following LVAD implantation remains considerably restricted. This could be due to the predominate use of continuous-flow pumps, which operate at a fixed rotational speed and do not adapt to exercise conditions. Therefore, current research is focused on whether, and to what extent, adaptations in pump speed can influence and improve patient exercise capacity. We performed a systematic PubMed literature search on this topic, and found 11 relevant studies with 161 patients. Exercise time, peak work load, total cardiac output (TCO), peak oxygen consumption (peak VO₂) and, if available, values at the anaerobic threshold (AT) were all taken into consideration. Possible complications were documented. This paper aims to compare the results from these studies in order to discuss the effects of pump speed adaptations on exercise capacity.

Clinical overview of the HVAD: a centrifugal continuous-flow ventricular assist device with magnetic and hydrodynamic bearings including lateral implantation strategies

Growing worldwide incidences of end-stage heart failure and declining rates of cardiac transplants have given rise to the need for alternative treatment options, based on mechanical circulatory support (MCS) devices such as left ventricular assist devices (LVADs). Technologically advanced LVADs such as the HVAD^® (HeartWare^®, Medtronic) facilitate safe and efficient treatment of heart failure patients with reduced post-operative complications, which is attributed to their considerably miniaturized size. This also facilitates the development and implementation of novel, minimally-invasive surgical techniques. The HVAD is a centrifugal pump, manufactured by HeartWare Inc., (Framingham, MA, USA) and subsequently by Medtronic Inc., (Minnesota, MN, USA), and has been approved for clinical application after receiving the CE Mark approval in 2008 and the FDA approval in 2012. Current research efforts are focused on further miniaturization alongside optimization of electronic and software controllers as well as implementation of the transcutaneous energy transfer (TET) technology. Salient features of the HVAD pump technology, clinical applications and future optimization strategies have been discussed in this article.