Medical and Mechanical Circulatory Support of the Failing Right Ventricle

PURPOSE OF REVIEW

To describe medical therapies and mechanical circulatory support devices used in the treatment of acute right ventricular failure.

RECENT FINDINGS

Experts have proposed several algorithms providing a stepwise approach to medical optimization of acute right ventricular failure including tailored volume administration, ideal vasopressor selection to support coronary perfusion, inotropes to restore contractility, and pulmonary vasodilators to improve afterload. Studies have investigated various percutaneous and surgically implanted right ventricular assist devices in several clinical settings. The initial management of acute right ventricular failure is often guided by invasive hemodynamic data tracking parameters of circulatory function with the use of pharmacologic therapies. Percutaneous microaxial and centrifugal extracorporeal pumps bypass the failing RV and support circulatory function in severe cases of right ventricular failure.

Oxygenated right ventricular assist device as part of veno-venopulmonary extracorporeal membrane oxygenation to support the right ventricle and pulmonary vasculature

COVID-19 infection can lead to severe acute respiratory distress syndrome (ARDS), right ventricular (RV) failure and pulmonary hypertension. Venovenous extracorporeal membrane oxygenation (V-V ECMO) has been used for patients with refractory hypoxemia. More recently dual-lumen right atrium to pulmonary artery oxygenated right ventricular assist devices (Oxy-RVAD) have been utilized in the severe medical refractory COVID ARDS setting. Historically, animal data has demonstrated that high continuous non-pulsatile RVAD flows, leading to unregulated and unprotected circulation through the pulmonary vessels is associated with an increased risk of pulmonary hemorrhage and increased amount of extravascular lung water. These risks are heightened in the setting of ARDS with fragile capillaries, left ventricular (LV) diastolic failure, COVID cardiomyopathy, and anticoagulation. Concurrently, due to infection, tachycardia, and refractory hypoxemia, high V-V ECMO flows to match high cardiac output are often necessary to maintain systemic oxygenation. Increase in cardiac output without a concurrent increase in VV ECMO flow will result in a higher fraction of deoxygenated blood returning to the right heart and therefore resulting in hypoxemia. Several groups have suggested using a RVAD only strategy in COVID ARDS; however, this exposes the patients to the risk of pulmonary hemorrhage. We present one of the first known cases using an RV mechanical support, partial flow pulmonary circulation, oxygenated Veno-venopulmonary (V-VP) strategy resulting in RV recovery, total renal recovery, awake rehabilitation, and recovery.

Temporary Right Ventricular Assist Device Support for Acute Right Heart Failure: A Single-Center Experience

INTRODUCTION

Severe right ventricular (RV) failure is associated with significant morbidity and mortality. Although right ventricular assist devices (RVADs) are increasingly used for refractory RV failure, there is limited data on their short- and long-term outcomes. Therefore, we undertook this study to better understand our experience with temporary RVADs.

METHODS

We conducted a retrospective review of all RVADS performed from 2017 to 2021. Patients supported with surgical RVADs, the Protek Duo device, and the Impella RP device were included. Patients were stratified by the type of RVAD and by etiology of RV failure. Survival was assessed by the Kaplan-Meier method and multivariable Cox proportional hazards regression models.

RESULTS

From 2017 to 2021, 42 patients underwent RVAD implantation: 32 with a Protek Duo, 6 with an Impella RP, and 4 with a surgical RVAD. Majority of patients were already supported with an alternate form of mechanical support. Most patients had impaired renal function, decreased hepatic function, and lactic acidosis at the time of cannulation. The median duration of RVAD support was 8.5 [5-19] d. Survival to decannulation was 68.4%, to discharge was 47.4%, and to 1-y was 40.2%. Multivariable analysis identified elevated total bilirubin levels to be associated with 30-d mortality while increased hemoglobin levels were protective. After RVAD cannulation, the median number of pressors and inotropes was lower (P < 0.01) and the lactic acidosis was less (P < 0.01).

CONCLUSIONS

In conclusion, RVAD support is associated with lower lactate levels, and decreased number of vasoactive medications, but is associated with significant morbidity and mortality.

Critical Care Management of the Patient with Pulmonary Hypertension

Pulmonary hypertension patients admitted to the intensive care unit have high mortality, and right ventricular failure typically is implicated as cause of or contributor to death. Initial care of critically ill pulmonary hypertension patients includes recognition of right ventricular failure, appropriate monitoring, and identification and treatment of any inciting cause. Management centers around optimization of cardiac function, with a multipronged approach aimed at reversing the pathophysiology of right ventricular failure. For patients who remain critically ill or in shock despite medical optimization, mechanical circulatory support can be used as a bridge to recovery or lung transplantation.

Mechanical Circulatory Support in Right Ventricular Failure

Right ventricular dysfunction presents unique challenges in patients with cardiopulmonary disease. When optimal medical therapy fails, mechanical circulatory support is considered. Devices can by classified according to whether they are deployed percutaneously or surgically, whether the pump is axial or centrifugal, whether the right ventricle is bypassed directly or indirectly, and whether the support is short term or long term. Each device has advantages and disadvantages. Acute mechanical circulatory support is a suitable temporizing strategy in advanced heart failure. Future research in right ventricular mechanical circulatory support will optimize device management, refine patient selection, and ultimately improve clinical outcomes.

Extracorporeal Membrane Oxygenation with Right Ventricular Assist Device for COVID-19 ARDS

Background: Right ventricular failure is an underrecognized consequence of COVID-19 pneumonia. Those with severe disease are treated with extracorporeal membrane oxygenation (ECMO) but with poor outcomes. Concomitant right ventricular assist device (RVAD) may be beneficial.

Methods: A retrospective analysis of intensive care unit patients admitted with COVID-19 ARDS (Acute Respiratory Distress Syndrome) was performed. Nonintubated patients, those with acute kidney injury, and age > 75 were excluded. Patients who underwent RVAD/ECMO support were compared with those managed via invasive mechanical ventilation (IMV) alone. The primary outcome was in-hospital mortality. Secondary outcomes included 30-d mortality, acute kidney injury, length of ICU stay, and duration of mechanical ventilation.

Results: A total of 145 patients were admitted to the ICU with COVID-19. Thirty-nine patients met inclusion criteria. Of these, 21 received IMV, and 18 received RVAD/ECMO. In-hospital (52.4 versus 11.1%, P = 0.008) and 30-d mortality (42.9 versus 5.6%, P= 0.011) were significantly lower in patients treated with RVAD/ECMO. Acute kidney injury occurred in 15 (71.4%) patients in the IMV group and zero RVAD/ECMO patients (P< 0.001). ICU (11.5 versus 21 d, P= 0.067) and hospital (14 versus 25.5 d, P = 0.054) length of stay were not significantly different. There were no RVAD/ECMO device complications. The duration of mechanical ventilation was not significantly different (10 versus 5 d, P = 0.44).

Conclusions: RVAD support at the time of ECMO initiation resulted in the no secondary end-organ damage and higher in-hospital and 30-d survival versus IMV in specially selected patients with severe COVID-19 ARDS. Management of severe COVID-19 ARDS should prioritize right ventricular support.

Novel percutaneous dual-lumen cannula-based right ventricular assist device provides effective support for refractory right ventricular failure after left ventricular assist device implantation

OBJECTIVES

Right heart failure after left ventricular assist device (LVAD) implantation is associated with significant morbidity and mortality. A new generation of percutaneous right ventricular assist devices (RVADs) may mitigate the need for invasive surgical RVAD implantation. The purpose of this study was to evaluate the safety and efficacy of the Protek Duo (TandemLife, Pittsburgh, PA, USA) RVAD in patients who developed severe acute right heart failure in the intensive care unit after LVAD implantation.

METHODS

This was a retrospective cohort study of 27 patients who received a Protek Duo after LVAD implantation from January 2016 to March 2019 at our centre. The primary outcome of interest was survival to hospital discharge. Secondary outcomes included procedural success, device-related complications and conversion to a surgical RVAD.

RESULTS

The median age of patients was 63 years (interquartile range 58-71), 78% were men and 78% were Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) profile 1 or 2. Patients were on a median of 2 inotropes and 2 pressors prior to Protek Duo insertion. The device successfully implanted on the first attempt in all patients a median of 1 day (interquartile range 1-2) after LVAD implantation and the median duration of support was 11 days (interquartile range 7-16). Device weaning occurred in 86% of patients, with 15% in-hospital mortality. Major complications related to the device included new moderate-to-severe tricuspid regurgitation (36%), haemolysis (14%) and cannula migration (7%). Three patients (11%) required conversion to surgical RVAD. Overall survival to 1 year was 81%.

CONCLUSIONS

The use of the Protek Duo as a percutaneous RVAD is a safe and feasible treatment for patients who develop acute right heart failure after LVAD implantation.

When Harry Met Sally: Single-Session INARI FlowTriever and Impella RP

Percutaneous mechanical thrombectomy devices have revolutionized the treatment of massive pulmonary embolism (PE) by providing a rapid, non-thrombolytic based method to re-establish right-sided circulation while reducing bleeding complications. However, with massive PE, the acute increase in right ventricular afterload results in a compounded hemodynamic compromise, which may necessitate the need for advanced cardiac support. This case exemplifies the need for a comprehensive and synergistic approach to the management of massive PE. To our knowledge, this is the first report of combination therapy using large bore mechanical suction thrombectomy (FlowTriever, INARI Medical, Irvine, CA, USA) in conjunction with the implantation of right ventricular mechanical support (Impella RP, ABIOMED, Danvers, MA, USA) in an effort to reverse the right ventricular "shock spiral." <Learning objective: To understand the importance of timely intervention in massive pulmonary embolism (PE) and the role of percutaneous mechanical thrombectomy devices in such situations where thrombolysis fails or is contraindicated. To incorporate the simultaneous use of mechanical circulatory support in the setting of massive PE.>.

Planned right ventricular support for combined heart-liver transplantation

Right ventricular dysfunction post heart transplantation (HTx) is a common problem and its likelihood to occur after combined heart-liver transplantation is even higher. The placement of an extracorporeal planned right ventricular assist device following the HTx during liver transplantation may assist in preventing this complication.

Concept, Evaluation, and Future Perspectives of PERKAT® RV-A Novel Right Ventricular Assist Device

Right heart failure (RHF) is a life-threatening condition. Mechanical right heart support offers an option for critically ill patients. The PERKAT® RV device is designed for percutaneous implantation in acute RHF. It consists of a nitinol chamber covered by foils containing inflow valves. An outlet tube is attached to its distal tip. Using an 18F sheath, it is implanted in the inferior vena cava while the tube bypasses the right heart with its tip in the pulmonary trunk. Then, an IABP balloon is inserted in the pump chamber. Balloon deflation generates blood inflow into the chamber; during inflation, blood is pumped into the pulmonary arteries. The device is capable of achieving flow rates of up to 3.5 l/min under in vitro conditions. In vivo, we were able to increase cardiac output by 59% in a sheep model of acute pulmonary embolism. Based on this, our further research will focus on first-in-human implants.

Right ventricular functional assessment by three-dimensional transesophageal echocardiography is useful for withdrawal from a right ventricular assist device: a case report

Right ventricular assist device (RVAD) implantation is one type of surgical treatment used for right heart failure. It is important to assess right ventricular (RV) function precisely when RVAD withdrawal is considered. Although assessment of RV function is difficult due to its complicated shape and contraction pattern, the volumetric analysis method of three-dimensional (3D) transesophageal echocardiography (TEE) has been developed and is useful for this task. We report the case of a 79-year-old man who successfully underwent RVAD withdrawal and evaluation using 3D TEE. 3D TEE had an important role in determining the timing of withdrawal from RVAD in this case.

Non-occlusive mesenteric ischemia in a patient with left ventricular assist device implantation

Non-occlusive mesenteric ischemia (NOMI) is a devastating complication after cardiac surgery. Once patients develop NOMI, intra-mesenteric infusion of vasodilators and/or emergent laparotomy is usually required, but the mortality is extraordinarily high even with intensive treatment. We present a case of salvage of a patient with NOMI complicated with severe right ventricular dysfunction after left ventricular assist device (LVAD) implantation using maximum treatment with emergent laparotomy and temporary right ventricular assist device implantation. To the best of our knowledge, this is the first successful salvage case of NOMI in a LVAD patient. We believe that hemodynamic optimization using maximum treatment is critically important to achieve salvage.

Application of a Lumped Parameter Model to Study the Feasibility of Simultaneous Implantation of a Continuous Flow Ventricular Assist Device (VAD) and a Pulsatile Flow VAD in BIVAD Patients

The aim of this work is to develop and test a lumped parameter model of the cardiovascular system to simulate the simultaneous use of pulsatile (P) and continuous flow (C) ventricular assist devices (VADs) on the same patient. Echocardiographic and hemodynamic data of five pediatric patients undergoing VAD implantation were retrospectively collected and used to simulate the patients' baseline condition with the numerical model. Once the baseline hemodynamic was reproduced for each patient, the following assistance modalities were simulated: (a) CVAD assisting the right ventricle and PVAD assisting the left ventricle (RCF + LPF), (b) CVAD assisting the left ventricle and PVAD assisting the right ventricle (LCF + RPF). The numerical model can well reproduce patients' baseline. The cardiac output increases in both assisted configurations (RCF + LPF: +17%, LCF + RPF: +21%, P = ns), left (right) ventricular volumes decrease more evidently in the configuration LCF + RPF (RCF + LPF), left (right) atrial pressure decreases in the LCF + RPF (RCF + LPF) modality. The pulmonary arterial pressure slightly decreases in the configuration LCF + RPF and it increases with RCF + LPF. Left and right ventricular external work increases in both configurations probably because of the total cardiac output increment. However, left and right artero-ventricular coupling improves especially in the LCF + RPF (-36% for the left ventricle and -21% for the right ventricle, P = ns). The pulsatility index decreases by 8.5% in the configuration LCF + RPF and increases by 6.4% with RCF + LPF (P = 0.0001). A numerical model could be useful to tailor on patients the choice of the VAD that could be implanted to improve the hemodynamic benefits. Moreover, a model could permit to simulate extreme physiological conditions and innovative configurations, as the implantation of both CVAD and PVAD on the same patient.

Minimally invasive approach for percutaneous CentriMag right ventricular assist device support using a single PROTEKDuo Cannula

Background

Right ventricular failure is a serious complication after left ventricular assist device placement.

Case Presentation

A 70-year-old male in decompensated heart failure with right ventricular failure after the placement of a left ventricular assist device. A single dual-lumen PROTEKDuo cannula was inserted percutaneously via the internal jugular vein to draw blood from the right atrium and return into the pulmonary artery using the CentriMag system, by passing the failing ventricle. The patient was successfully weaned from right ventricular assist device.

Conclusions

In comparison to two-cannula conventional procedures, this right ventrivular assist device system improves patient rehabilitation and minimizes blood loss and risk of infection, while shortening procedure time and improving clinical outcomes in right ventricular failure.

In-Series Versus In-Parallel Mechanical Circulatory Support for the Right Heart: A Simulation Study

Right heart failure (RHF) is a serious health issue with increasing incidence and high mortality. Right ventricular assist devices (RVADs) have been used to support the end-stage failing right ventricle (RV). Current RVADs operate in parallel with native RV, which alter blood flow pattern and increase RV afterload, associated with high tension in cardiac muscles and long-term valve complications. We are developing an in-series RVAD for better RV unloading. This article presents a mathematical model to compare the effects of RV unloading and hemodynamic restoration on an overloaded or failing RV. The model was used to simulate both in-series (sRVAD) and in-parallel (pRVAD) (right atrium-pulmonary artery cannulation) support for severe RHF. The results demonstrated that sRVAD more effectively unloads the RV and restores the balance between RV oxygen supply and demand in RHF patients. In comparison to simulated pRVAD and published clinical and in silico studies, the sRVAD was able to provide comparable restoration of key hemodynamic parameters and demonstrated superior afterload and volume reduction. This study concluded that in-series support was able to produce effective afterload reduction and preserve the valve functionality and native blood flow pattern, eliminating complications associated with in-parallel support.

Banding the Right Ventricular Assist Device Outflow Conduit: Is It Really Necessary With Current Devices?

Implantable left ventricular assist devices (LVADs) have been adapted clinically for right-sided mechanical circulatory support (RVAD). Previous studies on RVAD support have established the benefits of outflow cannula restriction and rotational speed reduction, and recent literature has focused on assessing either the degree of outflow cannula restriction required to simulate left-sided afterload, or the limitation of RVAD rotational speeds. Anecdotally, the utility of outflow cannula restriction has been questioned, with suggestion that banding may be unnecessary and may be replaced simply by varying the outflow conduit length. Furthermore, many patients have a high pulmonary vascular resistance (PVR) at the time of ventricular assist device (VAD) insertion that reduces with pulmonary vascular bed remodeling. It is therefore important to assess the potential changes in flow through an RVAD as PVR changes. In this in vitro study, we observed the use of dual HeartWare HVAD devices (HeartWare Inc., Framingham, MA, USA) in biventricular support (BiVAD) configuration. We assessed the pumps' ability to maintain hemodynamic stability with and without banding; and with varying outflow cannulae length (20, 40, and 60 cm). Increased length of the outflow conduit was found to produce significantly increased afterload to the device, but this was not found to be necessary to maintain the device within the manufacturer's recommended operational parameters under a simulated normal physiological setting of mild and severe right ventricular (RV) failure. We hypothesize that 40 cm of outflow conduit, laid down along the diaphragm and then up over the RV to reach the pulmonary trunk, will generate sufficient resistance to maintain normal pump function.

Bailout transcatheter closure of patent foramen ovale for refractory hypoxaemia after left ventricular assist device implantation

We describe the interdisciplinary management of a 59-year old man with ischaemic cardiomyopathy on a HeartMate II left ventricular assist device (LVAD) and temporary right extracorporeal membrane oxygenation (ECMO) as a bridge-to-heart transplantation. He suffered refractory hypoxaemia due to massive right-to-left shunting by a patent foramen ovale (PFO), diagnosed after weaning off of temporary right ECMO. Percutaneous closure of the PFO was successfully achieved with an Amplatzer septal occluder device, which allowed the patient's extubation and departure from hospital. The patient received heart transplantation 7 weeks after LVAD implantation and was discharged from the intensive care unit 2 weeks after transplantation.