What is the Impella 5.5 (Intra-Aortic Balloon Pump)?

From the Guidelines

The Impella 5.5 should be considered for patients with acute myocardial infarction complicated by cardiogenic shock, particularly those with persistent clinical hypoperfusion, hypotension, vasopressor requirement, or cardiac power output <0.6 W despite adequate filling pressures, as it may provide hemodynamic support and improve outcomes. The Impella 5.5 is a temporary mechanical circulatory support device that can be used to support the left ventricle in patients with severe heart failure or cardiogenic shock, providing up to 5.5 liters per minute of blood flow 1.

Key Considerations

• The device is inserted through a small incision in the chest and positioned through the axillary or subclavian artery, and can be used for up to 14 days 1.
• Management requires anticoagulation with heparin to maintain an activated clotting time of 160-180 seconds to prevent thrombosis, as well as regular monitoring of hemodynamics, device parameters, and potential complications such as bleeding, infection, or vascular issues 1.
• The device's effectiveness stems from its ability to reduce cardiac workload, improve end-organ perfusion, and provide time for cardiac recovery or decision-making regarding long-term treatment options, with observational studies reporting improved survival compared to historical controls 1.

Important Findings

• A study published in Circulation in 2021 found that the use of an Impella device was associated with improved outcomes in patients with acute myocardial infarction complicated by cardiogenic shock, with a significantly lower rate of death compared to a matched group of patients receiving no therapy 1.
• However, another study found that the use of an Impella device was associated with no difference in 30-day all-cause mortality compared to a matched group of patients from the IABP-Shock II trial, and was associated with higher rates of severe or life-threatening bleeding, vascular complications, and sepsis 1.
• The timing of device insertion and the severity of shock may influence outcomes, and more prospective studies are required to understand the clinical utility of the Impella 5.5 in ischemic and nonischemic forms of cardiogenic shock 1.

From the Research

Impella 55 Overview

• The Impella 5.5 device is a surgically inserted, trans-valvular, microaxial flow device capable of providing 5.5 L/min of continuous, antegrade flow from the left ventricle (LV) to the aorta 2.
• It is used for mechanical circulatory support in patients with cardiogenic shock or those undergoing high-risk percutaneous coronary intervention (PCI) 3, 4.

Clinical Applications

• The Impella 5.5 device is used in various clinical scenarios, including escalation of support for acute myocardial infarction cardiogenic shock (AMICS), transition from extracorporeal membrane oxygenation to mobile support, bridge to transplantation or durable MCS in acute decompensated heart failure, or perioperative use in post-cardiotomy cardiogenic shock (PCCS) 2.
• It allows for monitoring of left-heart recovery, optimizing right ventricular function, and rehabilitating patients to meet bridging endpoints 2.

Anticoagulation Protocols

• Anticoagulation protocols for patients with Impella devices are not well established and are complicated by concomitant use of purge solutions containing unfractionated heparin (UFH) and intravenous UFH continuous infusion (CI) for systemic anticoagulation 3.
• A modified UFH protocol targeting an anti-Xa goal of 0.3 to 0.5 units/mL may be a useful approach to achieve therapeutic anticoagulation while accounting for UFH exposure from the purge solution and minimizing need for frequent calculations 3.
• Lowering UFH-targets in left-Impella supported cardiogenic shock patients seems to be a safe and promising strategy for reducing major bleedings without increasing major cardiovascular and cerebrovascular adverse events (MACCE) 5.

Safety and Effectiveness

• The use of Impella devices has been shown to be effective in managing patients with cardiogenic shock and high-risk PCI, with improved survival rates compared to historical mortality rates 4.
• However, thromboembolic and bleeding events are frequent during percutaneous mechanical circulatory support (pMCS), and optimal anticoagulation regimes are still being explored 5.
• The Impella 5.5 device has been shown to have a low rate of thrombotic events, with a rate of overall thrombosis of 4.9% in one study 3.