Background

Acute right ventricular (RV) failure occurs in multiple settings, including acute myocardial infarction (MI), fulminant myocarditis, acute decompensated heart failure, acute pulmonary embolism, decompensated pulmonary hypertension, following cardiac transplant, and in post-cardiotomy shock. With the rapid rise in left ventricular assist device (LVAD) utilization for patients with advanced heart failure, one increasingly common scenario in which RV failure is encountered is following LVAD implantation. RV failure occurs in 0.1% of patients post cardiotomy, 2 to 3% following cardiac transplant, and in as many as 30-40% of patients after LVAD implantation.^1-4 The RV is often challenged in the period following LVAD insertion in a number of ways. First, with near normalization of cardiac output, RV preload increases dramatically. Second, it is challenged by altered geometry with septal shift towards the left ventricular cavity due to unloading by the device. Third, increases in pulmonary vascular resistance encountered in the perioperative period (e.g., due to cardiopulmonary bypass, pain, or hypoxemia) further compromise the failing ventricle. Finally, ventricular arrhythmias and defibrillator shocks may compromise RV function. RV failure after LVAD implantation portends increased morbidity and mortality.^2-4

Current Treatment Strategies

When RV failure occurs following LVAD implantation, the mainstay of treatment is inotropic and pulmonary vasodilator support while volume status is optimized. Dobutamine, milrinone, and epinephrine are first-line agents. In addition, vasopressors are often used to maintain coronary perfusion pressure. Inhaled nitric oxide is employed frequently to reduce RV afterload, especially while the patient is being mechanically ventilated. Other pulmonary vasodilators are used during the perioperative period as well as for long-term treatment. These therapies are initiated while any potential precipitants of RV failure are corrected (e.g., LVAD speed optimization, optimization of gas exchange, treatment of pain). However, these measures are frequently insufficient to augment RV systolic function, and mechanically circulatory support (MCS) is required to unload the RV, ensure adequate LV preload, and optimize tissue perfusion.

Currently Available RV Support Devices

Temporary mechanical circulatory support devices for RV failure are an attractive option because the RV function often improves sufficiently in a short period of time to allow for device removal. Often, such recovery can be expected in days to weeks, and several of the devices discussed below are approved for use for up to 14 days. Currently there are both surgical and percutaneous options for mechanical RV support.

Surgical right ventricular assist device (RVAD) implantation involves cannulation of the right atrium or RV as well as pulmonary artery. These are connected to an extracorporeal centrifugal flow pump. Numerous reports detailing use of a surgically-implanted temporary RVAD following LVAD have demonstrated that this is an effective strategy to support the patient through severe RV failure in the postoperative period.^5-6 However, patients requiring RVAD have consistently had worse outcomes than those who do not need an RVAD, even when compared to other patients with RV failure.^2-6 While effective, a surgical RVAD requires a repeat sternotomy if not placed at the same time as the LVAD. In addition, an RVAD with the above-described configuration requires a second surgery to remove the device when the patient is ready to be weaned. Many of these patients are at increased risk of bleeding because of hepatic dysfunction induced by congestion and/or hypotension encountered with RV failure.

More recently, percutaneous RVADs have been used in a variety of clinical scenarios. Several approaches have been described.^7-10 One involves placing two cannulas – typically either two femoral venous cannulas or one femoral and one internal jugular venous cannula – with one cannula positioned in the right atrium and another in the pulmonary artery. This strategy employs an extracorporeal centrifugal pump with the inflow from the right atrial cannula and outflow to the pulmonary artery. Several different centrifugal flow pumps have been used with this cannulation strategy.^7-9 Variations on this configuration include anastomosing a graft to the pulmonary artery and inserting a cannula through the graft. This allows for weaning of the pump without re-opening the chest. A novel dual-lumen co-axial cannula flexible enough to be positioned with its distal tip in the pulmonary artery from internal jugular insertion can be used with a centrifugal flow pump to achieve a percutaneous RVAD. Because of its internal jugular cannulation site, this configuration allows for ambulation during the period of support. Removal is typically via a pursestring suture at bedside.

Another option for percutaneous RV support is a novel axial-flow pump. This device utilizes a catheter-mounted microaxial flow pump with the inflow just below the right atrium-inferior vena cava junction and the outflow into the pulmonary artery after insertion via the femoral vein. Due to the design of the system, internal jugular placement and ambulation are not possible.

Clinical Trials

The majority of the literature detailing use of percutaneous RVADs consists of retrospective single-center or small multicenter studies utilizing a variety of pump technologies.^7-10 Patients in these studies have included predominantly post-LVAD recipients, but also post-cardiotomy shock patients, acute MI patients, and post-transplant patients. Despite the relatively high success of weaning from RVAD support in these reports, short- and long-term mortality remain high. This largely represents the mortality of patients with RV failure as opposed to a failure of device therapy.

Recently published, the RECOVER RIGHT trial is the first prospective, multicenter trial examining outcomes for a percutaneous RVAD.¹¹ A novel microaxial-flow pump was studied in a single-arm trial at 15 centers. Two groups of patients with RV failure were enrolled, the first after LVAD placement and the second consisting of a mixture of post-cardiotomy, post-transplant, and acute MI patients. The primary outcome was a combined endpoint of either survival at 30 days or at hospital discharge or survival to next therapy (e.g., transplant or surgical RVAD). Thirty patients were enrolled; of the 18 LVAD recipients and 12 non-LVAD recipients, 88.3% and 58.3% survived to the primary endpoint, respectively. Overall, 73.3% of patients survived to discharge. As expected, cardiac index, central venous pressure, and LVAD flows were all improved following device insertion. The major complication related to this device was postoperative bleeding which occurred in 36.6% of patients.

Conclusion

As increasing numbers of patients are undergoing LVAD implantation, the need for easily-deployed, safe, and effective devices for temporary support of the RV will continue to grow. Recent advances have resulted in several device options for percutaneous RV support. Though data demonstrating their efficacy is limited, these devices appear to be viable alternatives to surgically-implanted RVADs. Further prospective multicenter studies clarifying the optimal role for such devices are needed to evaluate their benefits and potential complications.

References

1. Kaul TK, Fields BL. Postoperative acute refractory right ventricular failure: incidence, pathogenesis, management and prognosis. Cardiovasc Surg 2000;8:1-9.
2. Dang NC, Topkara VK, Mercando M, et al. Right heart failure after left ventricular assist device implantation in patients with chronic congestive heart failure. J Heart Lung Transplant 2006;25:1-6.
3. Matthews JC, Koelling TM, Pagani FD, Aaronson KD. The right ventricular failure risk score a pre-operative tool for assessing the risk of right ventricular failure in left ventricular assist device candidates. J Am Coll Cardiol 2008;51:2163-72.
4. Kormos RL, Teuteberg JJ, Pagani FD, et al. Right ventricular failure in patients with the HeartMate II continuous-flow left ventricular assist device: Incidence, risk factors and effect on outcomes. J Thorac Cardiovasc Surg 2010;139:1316-24.
5. John R, Long JW, Massey HT, et al. Outcomes of a multicenter trial of the Levitronix CentriMag ventricular assist system for short-term circulatory support. J Thorac Cardiovasc Surg 2011;141:932-9.
6. Bhama JK, Kormos RL, Toyoda Y, Teuteberg JJ, McCurry KR, Siegenthaler MP. Clinical experience using the Levitronix CentriMag system for temporary right ventricular mechanical circulatory support. J Heart Lung Transplant 2009;28:971-6.
7. Haneya A, Philipp A, Puehler T, et al. Temporary percutaneous right ventricular support using a centrifugal pump in patients with postoperative acute refractory right ventricular failure after left ventricular assist device implantation. Eur J Cardiothorac Surg 2012;41:219-23.
8. Kapur NK, Paruchuri V, Korabathina R, et al. Effects of a percutaneous mechanical circulatory support device for medically refractory right ventricular failure. J Heart Lung Transplant 2011;30:1360-7.
9. Takayama H, Naka Y, Kodali SK, et al. A novel approach to percutaneous right-ventricular mechanical support. Eur J Cardiothorac Surg 2012;41:423-6.
10. Cheung AW, White CW, Davis MK, Freed DH. Short-term mechanical circulatory support for recovery from acute right ventricular failure: clinical outcomes. J Heart Lung Transplant 2014;33:794-9.
11. Anderson M, Goldstein J, Milano C, et al. Benefits of a novel percutaneous ventricular assist device for right heart failure: the prospective RECOVER RIGHT study of the Impella RP device. J Heart Lung Transplant 2015;34:1549-60.

Keywords: Arrhythmias, Cardiac, Cardiac Output, Cardiopulmonary Bypass, Catheterization, Central Venous Pressure, Defibrillators, Device Removal, Dobutamine, Epinephrine, Femoral Vein, Heart Atria, Heart Failure, Heart Transplantation, Heart-Assist Devices, Hypertension, Pulmonary, Hypotension, Milrinone, Myocardial Infarction, Myocarditis, Nitric Oxide, Pain, Perioperative Period, Pulmonary Artery, Pulmonary Embolism, Retrospective Studies, Sternotomy, Sutures, Vascular Resistance, Vasodilator Agents, Vena Cava, Inferior, Ventricular Dysfunction, Right, Ventricular Function, Right, Walking

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