SCCM Resource Library-RV Mechanical Circulatory Support Devices

Video Transcription

My name is Kush Talakhia, and I direct the Cardiothoracic Surgical ICU at Lenox Hill Hospital in New York City within the Northwell Health System.  I sincerely thank each one of you for being here today, and I sincerely thank the Society of Critical Care Medicine for giving me the opportunity to talk about right ventricular  mechanical circulatory support. I have no disclosures. RV failure is a major cause of global morbidity and mortality for patients with acute myocardial  infarction, patients undergoing cardiotomy, patients with advanced heart failure, and patients with pulmonary hypertension.  Right ventricular acute mechanical circulatory support is an important step in the management  of RV failure, and it provides an opportunity to rapidly stabilize these patients with cardiogenic  shock due to right ventricular failure if these patients remain refractory to maximal ionotropic and vasopressor therapy.  And mechanical circulatory support should be considered early and initiated early. How do we select which patient gets right ventricular mechanical circulatory support?  One, early diagnosis is key. With the use of hemodynamic, echocardiographic, and laboratory parameters, identify the patient  who is remaining refractory to ionotropic and vasopressor therapy and developing worsening global perfusion. Two, very important to assess every function.  Does this patient have biventricular failure or is it isolated RV failure?  Three, rule out pericardial diseases, including causes of constrictive or restrictive physiology.  And four, focus on reversible causes of RV failure, such as acute myocardial infarction and pulmonary embolism.  Next, assess whether the patient requires oxygenation or not, support for oxygenation or not.  And keep in mind, these patients will require ongoing continuous hemodynamic monitoring,  including indices that include but not limited to pulmonary RV pulsatility index, for example,  the RA to wedge pressure ratio, for example, the FICC cardiac output, for example, to name a few. These patients will require the pulmonary RV catheter to remain in place.  As Maureen and colleagues pointed out, a pulmonary RV pulsatility index of less than 1.85 is a very sensitive indicator of RV failure after LVAD placement.  As is the RA to wedge pressure ratio of greater than 0.86 being a very sensitive predictor  of RV failure after LVAD placement. Now once we've identified the patient who requires RV mechanical circulatory support, it is very important to define the exit strategy.  Is the assist therapy going to be a bridge to recovery? Or is it going to be a bridge to transplant? Or is it going to be a bridge to definitive therapy?  It may well be a bridge to decision. But if it is going to be a bridge to nowhere, then there is no purpose in pursuing therapy that is going to be futile.  Now historically, RV mechanical circulatory support were ventricular assist devices that were surgically implanted pulsatile pumps with valves located within the inflow and  the outflow cannulae.  The earliest RV support devices were pulmonary artery balloon counterpulsation pumps. However, these were limited by the need for surgical implantation and variable effects  on RV afterload. In the early 1990s, rotary flow RVADs demonstrated hemodynamic superiority and better clinical outcomes.  The second and third generation surgical pumps now include rotodynamic pumps that transfer rotational kinetic energy to the circulation.  The present day percutaneously implanted mechanical circulatory support devices for RV failure.  And the benefits of percutaneously implanted devices include early intervention and bedside placement using the Seldinger technique as opposed to surgical placement.  The percutaneous devices are classified into direct RV bypass systems and indirect RV bypass systems.  The direct RV bypass systems bypass the blood directly from the RA to the PA, directly bypassing the right ventricle.  And these include the axial flow type impella RP system or the extracorporeal centrifugal flow type tandem RVAD and the ProtecDuo dual lumen cannula extracorporeal system.  The VA ECMO provides indirect RV bypass. Now management of patients with ventricular assist devices requires some knowledge of  the pressure head to device flow curve, what is the HQ curve. Flow through all rotary flow mechanical circulatory support devices depends on the preload and the afterload.  The device flow Q is directly proportional to the RPMs of the impeller and indirectly related to the pressure gradient between the inlet and the outlet.  The pressure gradients in the right sided circuit are not as high as those on the left side of the circuit and hence the flow variation is not as large.  But it is important to note that RV failure due to acute myocardial infarction, for example,  due to impaired contractility, in this scenario, the pressure head is small and hence the device flow is going to be higher for a fixed RPM.  As opposed to RV failure due to pulmonary hypertension, where the pressure head is going to be larger and the device flow will be lower for the same RPMs.  Starting with the direct RV bypass systems, the impeller RP and the tandem heart RVAD, as also the protect dual lumen cannula displaces blood from the right atrium to the pulmonary  artery, thereby directly bypassing the right ventricle. The impeller RP includes a 22 French impeller mounted on an 11 French microaxial flow catheter  that delivers blood from the RA to the PA. A 23 French venous peel away sheath sits in the pulmonary artery, requires a single venous access site, usually the femoral vein.  And after removal, the venous access site is closed with manual compression and mattress or deep pursing suture. Keep in mind, this device cannot be used to oxygenate the patient.  And Dr. Anderson and colleagues for the recover right trial reported significant improvements  in hemodynamic parameters in patients with RV failure following the impeller RP placement. A point to take home is that these patients develop significant hemolysis.  The right-sided impeller develops significant hemolysis, and this can sometimes be a problem.  The tandem heart RVAD is a direct RV bypass system, which uses an extracorporeal centrifugal flow pump to deliver blood from the RA into the main PA.  The inflow cannula is placed in the RA, and a second outflow cannula is inserted into the main pulmonary artery.  Point to note here is inflow and outflow are terms in reference to the extracorporeal flow pump, not to the patient.  Access is obtained via both femoral veins, and in patients with long torsos, the outflow cannula can be placed into the main pulmonary artery via the right internal jugular vein.  This approach can also be used if there are limitations to femoral vein access due to infection or thrombosis, or if a patient has an IVC filter in place.  And significant benefits using the tandem heart RVAD system have been reported in patients with acute myocardial infarction, patients after an LVAD implantation, patients developing  RV failure after an LVAD implant, patients with severe pulmonary hypertension and severe acute MR, and patients undergoing cardiac rejection after heart transplant.  Now, use of the right internal jugular access site for cannulation led to the development of the ProtecDuo dual lumen cannula, which is a 29 French or a 31 French cannula with  an extracorporeal centrifugal flow pump used for direct RV bypass. One lumen serves as an inflow cannula with a series of inflow vents across the SVC into  RA, inflows into the extracorporeal pump, and the second lumen has multi-fenestrated distal tip to deliver blood into the main pulmonary artery.  And an oxygenator can be spliced into the circuit for systemic oxygenation in addition to RV support, what is an oxy-RVAD configuration.  And recent literature has described significant benefits following the ProtecDuo implantation  for patients with RV failure in the setting of LVAD implantation and patients with cardiogenic shock resulting from decompensated severe pulmonary hypertension.  Coming to VA-ECMO, VA-ECMO is an indirect RV bypass system. It drains blood from the right atrium or both the right atrium and the pulmonary artery,  making it a VVA configuration, and VA-ECMO can be implanted at the bedside, can be used in patients undergoing cardiac arrest, what is ECPR, and the VVA configuration is where  there are two venous inflow cannula, one placed in the RA and one draining the pulmonary artery.  A point to take home is that the inflow into the arterial circuit directly into the aorta is going to increase the LV afterload.  And if the LV function is impaired, or if this bypass is being used for patients following cardiotomy, then the increase in LV afterload will give rise to an increase in the LA and  TA pressure and progressive acute lung injury and will worsen the outcomes. The increase in LV afterload will give rise to myocardial overdistension, and this is  especially a problem if this support is being used for patients requiring myocardial recovery following cardiotomy.  These patients will require an LV vent to decompress the LV and prevent myocardial overdistension and worse outcomes.  LV venting is offered by placing an intra-aortic balloon pump or a left-sided impella or an LA or LV vent cannula.  The benefits of VA ECMO on isolated RV failure remain largely undefined. The intra-aortic balloon pump does not directly support the RV, will help reducing RV afterload,  but the recent literature shows limited efficacy in patients with isolated RV failure. Now an important point to take home is that the isolated use of an RV mechanical circulatory  support device in the setting of impaired LV function can lead to LV volume overload and acute pulmonary injury.  On the flip side, isolated LV support in the setting of biventricular failure leads to LV suction as a result of limited preload supplied to the failing RV.  And in these cases, biventricular support needs to be considered. When is it time to consider decanalation?  Signs of recovery will include improved pulsatility, reduction in PA pressures, resolution of transaminitis, improved echocardiographic findings. And how long would this take?  Three to five days in patients requiring myocardial recovery post-cardiotomy, five to seven days  following acute myocardial infarction after revascularization, and weeks in patients with myocarditis.  Now durable right ventricular assist devices include surgically implanted pulsatile devices which require thoracotomy or sternotomy.  The hardware ventricular assist device is an axial flow pump not yet approved in our  country and the circulite synergy is a miniaturized axial flow pump which is in preclinical models as of yet. Can RV mechanical circulatory support be used electively?  Yes, elective use is for high-risk interventional procedures, high-risk complex percutaneous  coronary interventions, for example, high-risk tracheal reconstructions, for example, high-risk pulmonary thrombectomies, for example.  Are there any contraindications to RV mechanical circulatory support? No absolute contraindications, however, avoid this if it seems that the therapy is going  to be a bridge to nowhere. These patients will require anticoagulation and hence if the patients have expanding intracranial  hemorrhage or significant trauma or significant immune compromise, then these would be deemed  as relative contraindications as also patients with malignancy and limited life expectancy or patients with advanced liver disease or advanced immune suppressive states, then these  would be bridge to nowhere scenarios. Even with the advent of the recent less thrombogenic circuits, the circuits are going to be thrombogenic  and endothelial injury besides the turbulent flow and shear stress besides the blood stasis will give rise to thrombogenicity and these patients will require anticoagulation.  Heparin is the agent of choice. Platelets will get consumed by these circuits and extracorporeal circulation. Should heparin-induced thrombocytopenia be even considered?  This is a matter of daily debate, but it should be looked for if the trend seems to be in a rapid downward direction and if the assay is positive, then switch heparin to  a black thrombin inhibitor. Reverses in pharmacologic and pharmacokinetic dose adjustments of agents is important because  of the increased volume of distribution, knowledge of protein binding and the importance of knowledge of sequestration by the circuit.  Keep in mind, these doses will need to be reversed once the patient is weaned off of mechanical circulatory support, especially important in patients with antimicrobials,  anti-epileptic drugs, for example, in order to achieve therapeutic efficacy. Complications include complications due to cannula placement, vascular access complications  including limb ischemia, limb compartment syndrome, cannulocyte bleeding, hemolysis  and heparin-induced thrombocytopenia and neurologic complications in biventricular configurations.  Catastrophic complications due to accidental decannulation and equipment malfunction can also occur.  One important point to take home is that chatter in patients with right-sided mechanical circulatory support does not translate into the need for administering IV fluids.  In right-sided mechanical circulatory support, reduce the RPMs and reduce the blood flow in case of chatter and also look for troubleshooting.  With that said, setting up a successful mechanical circulatory support program requires a strong institutional commitment for the huge amount of infrastructure that is needed.  And the successful outcomes entirely rely upon a team that fosters a strong, close-knit, interdisciplinary and interdepartmental culture of close-knit collaboration and networking.  A team that fosters strong hand-off communication, which I remain an extremely strong proponent of, and a team that adopts checklists.  Checklists improve safety and reduce mortality and improve outcomes. And above all, a team that shares a vision, a vision towards unparalleled delivery of  care through teamwork, collaboration, innovation, and persistence for excellence. I want to thank you for your attention and I'll be happy to take questions if any.

Video Summary

In this video, Dr. Kush Talakhia discusses the use of right ventricular mechanical circulatory support in patients with RV failure. RV failure is a common cause of morbidity and mortality in patients with heart conditions. Mechanical circulatory support can stabilize patients with refractory RV failure and improve their outcomes. The key to selecting patients for support is early diagnosis and identification of reversible causes of RV failure. Dr. Talakhia explains the different types of support devices available, including direct RV bypass systems like the impella RP and tandem heart RVAD, and indirect systems like VA ECMO. He also discusses the management of patients with these devices and the importance of monitoring hemodynamic parameters. Dr. Talakhia emphasizes the need for a multidisciplinary approach and strong institutional support when setting up a successful mechanical circulatory support program.

Asset Subtitle

Cardiovascular, 2022

Asset Caption

Acute right ventricular (RV) failure is becoming more common in the ICU, especially in patients with acute respiratory distress syndrome (ARDS) on mechanical ventilation. Differences between left ventricular (LV) and RV physiology are important and are not always fully appreciated. Current treatment entails pharmacologic support while volume status is optimized. These measures are frequently insufficient to augment RV systolic function. Recent advances have resulted in several device options for mechanical RV support, both percutaneous and surgically implanted. Critical care physicians have a growing involvement in decisions about when temporary support is appropriate and how this is best accomplished. Mechanically circulatory support may be required. This session will review RV physiology, clinical scenarios warranting RV support, pharmacotherapy, and mechanical support options.

Meta Tag

Content Type Presentation

Knowledge Area Cardiovascular

Knowledge Level Intermediate

Knowledge Level Advanced

Learning Pathway Cardiothoracic Critical Care

Membership Level Select

Tag Cardiovascular

Tag Heart Failure

Tag Cardiothoracic Critical Care

Year 2022

Keywords

RV failure

mechanical circulatory support

refractory RV failure

support devices

patient management

hemodynamic parameters

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