Escalation of Care for the Decompensated Heart Failure Patient: The Ochsner Heart and Vascular Institute Experience With Axillary Placement of Impella 5.0

Abstract

Mechanical support devices have long been used in patients undergoing high-risk percutaneous interventions and to treat patients who present with hemodynamic instability and cardiogenic shock. Surgical left ventricular assist devices and cardiopulmonary bypass systems have been utilized to provide increased levels of hemodynamic support; however, these devices are associated with significant morbidity. There have been considerable advancements in developing safe, effective, easy-to-use, miniaturized, mechanical support devices in patients undergoing high-risk percutaneous revascularization and to treat hemodynamic instability.

The Impella^® 2.5 (Abiomed, Danvers, Mass.) is an intravascular microaxial blood pump that supports the circulatory system. The catheter is inserted percutaneously through the femoral artery and into the left ventricle. The Impella 2.5 received 510(k) clearance for partial circulatory support for up to 6 hours from the U.S. Food and Drug Administration in June 2008, and is CE (Conformité Européenne [European Conformity]) marked in Europe for circulatory support for up to 5 days. A larger device, the Impella 5.0, delivers up to 5 L/min of flow. Herein, we present a case of a patient who was treated with the Impella 5.0 and describe our institution’s experience with this device.

Introduction

Percutaneous mechanical left ventricular assist devices (LVADs) have long been used in high-risk patients undergoing percutaneous coronary interventions and in patients with severely compromised left ventricular function, i.e. cardiogenic shock (CS).  These devices have been used prophylactically to avoid hemodynamic embarrassment, and therapeutically, to treat hemodynamic instability.^1-4 Intra-aortic balloon pumps (IABP), the most widely used mechanical devices for hemodynamic support, do offer some benefit, but their limited hemodynamic support has been a stimulus to develop more effective devices.^5-8

There is a large body of evidence utilizing the Impella 2.5, including a prospective North American registry, The USpella, which followed patients undergoing PCI with Impella support for high-risk percutaneous coronary intervention (PCI) and acute myocardial infarction (AMI) complicated by CS. The high-risk PCI cohort included 178 patients with multiple co-morbid conditions, including an average left ventricular ejection fraction (LVEF) of 31% and half of the patients were classified as requiring urgent care. These patients included those with an unprotected left main coronary artery (LMCA) or last patent conduit in 56% of the population with an elevated average SYNTAX score of 36. The 30-day mortality was 4.5%. Ninety-one patients had a baseline and post-procedural assessment of cardiac function, which revealed a significant improvement in LVEF following device-assisted revascularization (31 ± 15% to 36 ± 14%, p < 0.001).⁹

The USpella AMI Shock Registry included 71 patients with AMI and CS who were supported with the Impella device. Prior to placement of the Impella, 78% were on ionotropic support, 42% required an IABP, and 85% had a patent infarct-related artery. With Impella support, there were significant increases in cardiac output and mean arterial pressure with a significant reduction in wedge pressure compared to baseline. The 30-day survival was 58%, with 7% of patients being bridged to a surgical LVAD and 3% receiving cardiac transplantation. A post-hoc analysis of the data showed that those patients who received Impella placement prior to revascularization had a significant reduction in 30-day mortality.⁹

There are several case reports describing the use of the Impella 5.0 device, including treating patients with CS and decompensated heart failure. The device has been used as a bridge to surgical LVADs, coronary artery bypass graft surgery (CABG), and cardiac transplantation.^10-12 Herein, we describe the use of the Impella 5.0 device in a patient who presented with decompensated heart failure.

Case Report

The patient was a 33-year-old male with nonischemic cardiomyopathy (LVEF 10%) who presented with worsening heart failure. He was initially treated with furosemide (Lasix) and dobutamine infusions and was transferred to our facility for consideration of heart transplantation and further care. The patient’s clinical status deteriorated with renal failure and liver dysfunction. He experienced ventricular tachycardia and was cardioverted, intubated and started on amiodarone. At this point, it was decided to place a hemodynamic support device.

The patient was taken to the hybrid operating suite where the surgeon made a small incision below the left clavicle and the axillary artery was exposed. The patient was heparinized for an activated clotting time (ACT) greater than 200 seconds. Vessel loops were placed proximally and distally around the artery. An 8 mm Dacron graft was spatulated and anastomosed with the artery with a running 4-0 suture. A 9 French (Fr) sheath was tied to the end of the graft to prevent blood loss. Through the sheath, a diagnostic Amplatz catheter was placed into the left ventricle, and an 0.014-inch stiff guidewire was passed though the catheter. The 9 Fr sheath and Amplatz catheter were removed, and the Dacron graft and wire was clamped. The Impella 5.0 device was back-loaded onto the stiff 0.014-inch wire and placed under fluoroscopic guidance into the left ventricle. Once proper placement was confirmed, the pump was started with immediate increase in cardiac output and mean arterial pressure, and a dramatic drop in his wedge pressure. The graft was trimmed, the device was secured, and the incision was closed in layers, with the device exiting the lateral portion of the incision. Over the next two weeks, the patient was maintained on Impella support at performance level 8 (30,000 RPMs) with the pump providing 4.2–4.6 L/min. Post implant, the patient’s cardiac outputs and mixed venous saturations markedly improved, and his liver dysfunction resolved. The patient’s clinical course was significant for intermittent dialysis and two episodes of sustained ventricular tachycardia, which was reasonably well tolerated. As he became more hemodynamically stable, pressors were weaned and subsequently, the Impella device was weaned to the lowest level of support. The device was explanted post-op day 14. At the time of this writing, the patient is on medical therapy, rehabilitating in the hospital, and is expected to be discharged soon.

Discussion

Patients who present with acute and decompensated heart failure represent challenging clinical scenarios, are often refractory to ionotropes and IABPs, and frequently need escalation of their care. The Impella 5.0 is able to provide flow as high as 5 L/min. This microaxial blood pump decreases pulmonary capillary wedge pressure, increases cardiac output and mean blood pressure, and improves organ perfusion.¹³ The Impella 5.0 device is an attractive device to deliver short-term mechanical support without cardiopulmonary bypass in patients who are failing conventional therapies. Lamarche et al published a retrospective analysis in cardiogenic shock patients who received either an Impella device (n=29) or extracorporeal life support (n=32). There were trends towards decreased 30-day mortality (38% vs. 44%) and more patients discharged from the hospital (59% vs. 41%) in the Impella-treated group.¹⁴

We have treated a total of 9 patients with the Impella 5.0 device (and 47 with the Impella 2.5) at our institution over the past 12 months. One patient presented with postcardiotomy cardiogenic shock following urgent CABG and mitral valve repair after she presented with a lateral wall MI and acute ischemic mitral regurgitation. One patient presented with acute fulminant myocarditis, and the other 7 patients presented with acute on chronic heart failure. The average age of the patients is 47 ± 13 years. Overall hospital mortality rate is 22.2%. Average LVEF was 17% ± 7. Four of the patients were ultimately bridged to surgical LVADs, all of whom are still alive. Two other patients were discharged on medical therapy alone.

Patients with end-stage heart failure have a very poor quality of life and high mortality rates. While cardiac transplantation is associated with high 1- and 10-year survival rates, there is a limited supply, and < 10% of patients actually undergo transplantation. LVADs are now an important therapeutic modality in treatment of patients with end-stage heart failure. There are numerous preoperative patient characteristics that affect surgical LVAD placement and increase operative mortality. These include renal dysfunction, hepatic congestion, low serum albumin, lactic acidosis, anemia, elevated INR, and inontropes therapy.^15,16 Our surgical colleagues are often reticent to place surgical LVAD if a patient has any of these risk factors and we have been asked to place percutaneous LVAD in an attempt to optimize these patients prior to surgery. We find the Impella device as a bridge to surgical LVADs to be an excellent strategy in this difficult-to-treat patient population.

We specifically like the axillary approach. It allows for a more stable placement, avoids the problems of significant illiofemoral atherosclerosis, and obviates the need for the supine position.

Dr. Grise can be contacted at mgrise@ochsner.org.

References

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Disclosure: Dr. Grise reports he is an Advisory Board member for Abiomed, Eli Lilly Corporation, and Daiichi Sankyo Corporation.