**3. Implantation of an Impella® device**

In general, the implantation of an Impella® device is comparatively easy procedure that is performed in a cath lab. However, pitfalls and limitations should be well known and implantation should be performed by an experienced team, including an interventional cardiologist, cath lab assistance, and a nurse.

Several contraindications that include vascular pathologies reaching from the femoral artery up to the aortic valve as well as aortic valve pathologies must be observed prior to implantation. These include, but are not limited to, severe peripheral artery vessel disease (pAVD) that may increase the likelihood of vascular access complications or may render the implantation of a large sheet and thereof the Impella® impossible, as well as aortic aneurism both abdominal and thoracic. Aortic insufficiency (moderate to severe degree), severe aortic stenosis, pathologies that increase the likelihood of thromboembolic events (valve endocarditis, LV thrombus) or a mechanical aortic valve may present further contraindications. Due to the administration of aPTT-relevant doses of unfractionated heparins in the purge fluid, bleeding risk may be increased. In patients with contraindications to unfractionated heparins, such as heparin-induced thrombocytopenia (HIT), using an alternative anticoagulant through a systemic line is at the discretion of the treating physician. Furthermore, pathologies that decrease right ventricular function may concomitantly decrease left ventricular preload, leading to insufficient Impella® output.

**2. Hemodynamic effects of Impella® support**

decreased cardiac oxygen consumption.

nary perfusion during protected PCI.

cath lab assistance, and a nurse.

**3. Implantation of an Impella® device**

output.

184 Interventional Cardiology

decreased.

heart rhythm. However, blood flow is dependent on after and preload.

Impella® hemodynamic support exhibits effects on intracardiac volumes and pressures as well as on systemic circulation, leading to augmentation of blood flow independent from

During systole, the pressure gradient between aorta and LV is at its lowest, accounting for the highest pump flow and motor current. Vice versa, the increased pressure gradient during diastole between LV and aorta leads to diminished motor current and transvalvular blood flow. These periodic changes result in a sinus-like curve of motor current and blood flow on the AIC. This information is integrated and used by the AIC to control the pumps position. Accordingly, decreased preload may therefore result in reduced Impella®

Hemodynamic changes in patients on Impella® support are most profound in patients with CS. In CS, a decreased cardiac index leads to volume overload of the left ventricle resulting in a dilating left ventricular chamber accompanied by increased left ventricular end-diastolic pressure (LVEDP). Concomitantly, increased wall tension of the LV causes increased myocardial oxygen consumption. The increased LVEDP may also result in heart failure with lung edema, further decreasing overall oxygen supply. The positive effects of LV unloading by Impella® support are best explained using pressure-volume (PV) loops. Impella® support leads to a left shift of the PV loop resulting in a reduction of LVEDP and a reduction of area under the PV loop curve. This resembles reduced cardiac work, overall consistent with

In a study by Schiller et al., cardiac index improved from 2.1 l/min/m2 to 3.8 l/min/m<sup>2</sup>

Additionally, mixed venous saturation increased from 56 to 68% and diuresis increased from 69 ml/h at device insertion to 105 ml/h on support indicating improved systemic perfusion. Central venous pressure, lactate levels, and inotropic support, all consequently

Apart from patients in CS, a case study by Arain and O'Meallie demonstrated an increase in coronary artery circulation on Impella® support in a patient undergoing protected PCI. Fractional-flow reserve (FFR) and coronary flow reserve (CFR) were measured in a hemodynamically significant stenotic left anterior descending (LAD) coronary artery using a pressure wire. While FFR remained the same comparing on- and off Impella® support time points, CFR significantly increased. This demonstrates beneficial effects of Impella® support on coro-

In general, the implantation of an Impella® device is comparatively easy procedure that is performed in a cath lab. However, pitfalls and limitations should be well known and implantation should be performed by an experienced team, including an interventional cardiologist,

[2].

Prior to implantation of the Impella device, we therefore recommend duplex-angiography of the respective arterial vessel considered for vascular access to: (I) measure vessel diameter and (II) exclude relevant pAVD and heavy calcifications. If bedside duplex-angiography is not available, and in case of a femoral approach, vascular access at the contralateral femoral artery and placement of a 6 F sheet may be performed. The status of the ipsilateral femoral artery may be determined via angiography through a 5 F pigtail catheter placed just above the origin of the two iliac arteries. This technique may also help to determine the location of the common femoral artery (CFA) and the best spot for needle introduction. The contralateral sheath may be left in place and later be used for introducing guide catheters and wires for coronary interventions. To exclude relevant pathologies of the aortic valve and to exclude the presence of intraventricular thrombi, echocardiography is recommended to determine whether Impella® support is feasible.

The respective Impella® device is assembled according to the manufacturers' instructions and following the steps laid out on the AIC by the cath lab assistance. For the Impella® 2.5 and CP, the CFA is punctured and a sheath is inserted after dilatation using the provided set. Before insertion of the sheath, we recommend using a pre-close technique to facilitate sheath removal. This technique requires the insertion of two Perclose Proglide® devices prior to placing the sheaths. A needle is used to puncture the CFA and a wire is introduced into the vessel. Two 6 F Perclose Proglide® devices are then introduced. The first device is placed at a 30–45° angle and before complete removal of the first carrier device, the 0.035-inch guide wire is reinserted into the CFA. A second Perclose Proglide® device is then introduced at a 90° angle in relation to the first device and introduced. Following the end of the procedure, the sutures are cinched down after catheter removal to close the arteriotomy. This technique is only feasible in patients undergoing protected PCI, as long indwelling times render the vascular closure set unsterile.

A pigtail catheter is now advanced into the LV, followed by a 0.018-inch wire and the pigtail catheter is removed again over the wire. Under fluoroscopic guidance, the Impella® is now advanced over the wire so that the outlet area rests above the aortic valve (**Figure 3**). After removal of the guide wire, correct position should once again be confirmed using the AIC and fluoroscopy before starting the procedure. During each transfer of the patient, care should be taken to avoid Impella® movement and correct position of the Impella® should be confirmed after the transfer using bedside echocardiography.

**Figure 3.** Correct position of the Impella 2.5 in the left ventricle with the outlet portion above the aortic valve demonstrated by fluoroscopy from an RAO (right anterior oblique) angle.

### **4. Adverse events**

Potential adverse events following Impella® implantation or hemodynamic support with Impella® include hemolysis, functional mitral stenosis, pump displacement, malfunction and vascular site complications including bleeding and limb ischemia. Furthermore, thromboembolic events including stroke and myocardial infarction as well as acute kidney dysfunction or failure might occur. Overall incidence rate is low, seems to differ according to the indication for hemodynamic support, and is also most likely related to the duration of Impella® support. Highest rates for adverse events may accordingly be found in patients undergoing Impella® support for CS.

In 120 patients with AMI complicated by CS, The EUROSHOCK trial found major bleeding at the vascular access site in 28.6%, hemolysis in 7.5%, and pericardial tamponade in 1.7% [3]. In another study including 40 patients with end-stage heart failure and implantation of an Impella® 5.0 as bridge to transplant or bridge to left ventricular assist device (LVAD), bleeding requiring transfusion occurred in 28.0%, hemolysis in 8.0%, device malfunction in 10.0%, and limb ischemia in 3.0% [4]. Highest rates of adverse events were generally found for major bleeding at the access site and hemolysis, two complications that may usually be managed successfully while patients may remain on Impella® support.

In patients undergoing protected PCI, the frequency of adverse events is usually lower. The PROTECT trial, designed to examine the efficacy and safety of Impella® 2.5 in protected PCI, found mild, transient hemolysis in 10.0% of patients with no other major adverse events [5]. In a further study including 19 patients undergoing protected PCI, no complications occurred [6].

Recent case reports have reported mitral valve damage possibly caused by Impella support [7]. Whether this finding warrants specific precautions needs to be further evaluated. We recommend screening for signs and symptoms of acute mitral insufficiency under Impella® support and further echocardiographic examinations on a regular basis.

Davis et al. reported a case in which a patient in CS developed acquired von-Willebrand syndrome (AVWS) under Impella 5.0 support [8]. AVWS develops in situations in which high shear stress leads to excessive proteolysis of von Willebrand factor (VWF) and loss of high molecular weight multimers, in this situation attributed to high-level Impella support. The patient suffered major bleeding under surgery for long-term LVAD and required massive substitution of blood and coagulation products. Larger trials are warranted to further evaluate alterations of VWF and the incidence of AVWS under Impella support.
