**5. Implantation technique of Impella 5.0/5.5**

The Impella 5.0/5.5 can be implanted *via* the axillary or subclavian artery [15], innominate artery [16, 17], and the ascending aorta (**Figure 3**) [18–20]. Since sternotomy is usually performed at the time of coronary artery bypass grafting, our favorite approach is through the ascending aorta. One of the advantages of the ascending aorta route is the nonnecessity of intraoperative fluoroscopy, which is usually required in the axillary or subclavian artery insertion.

The indications for use of Impella 5.0/5.5 are (a) severe left ventricular dysfunction (left ventricular ejection fraction <30%); (b) estimated prolonged use of cardiopulmonary bypass; (c) comorbidities such as liver disease, chronic kidney disease, chronic obstructive pulmonary disease, and peripheral vascular disease; (d) poorquality targets, and a combination of these. The contraindications for use of Impella

*Perioperative Use of Impella 5.0/5.5 in High-Risk Coronary Artery Bypass Grafting DOI: http://dx.doi.org/10.5772/intechopen.113370*

**Figure 3.** *A scheme of Impella 5.5 insertion via the right axillary artery (left) and innominate artery (right).*

5.0/5.5 are (a) mechanical aortic valve prosthesis, (b) aortic valve stenosis (equivalent to an orifice area of 0.6 cm2 or less), (c) moderate to severe aortic insufficiency, (d) severe right heart failure, (e) combined cardiorespiratory failure, and (f) left ventricular thrombus.

We prefer to place Impella 5.5 prophylactically in high-risk cases, rather than placing it emergently after failing to wean cardiopulmonary bypass.

Our technique for Impella 5.5 placement *via* the ascending aorta is (a) initiation of the cardiopulmonary bypass with a distal ascending aorta cannulation; (b) a partial aortic clamp on the ascending aorta and aortotomy with adequate length; (c) a beveled 10-mm graft anastomosis to the ascending aorta in a side-to-end fashion at least 7 cm above the aortic valve; (d) a small incision is made in the left neck, and the 10 mm graft is tunneled above the skin; (e) aortic cross clamp and completion of coronary artery bypass grafting as usual; (f) insertion of Impella sheath through the 10-mm graft; (g) advancement of J-wire and pig-tail catheter into the left ventricle under a transesophageal echo guidance; (h) advancement of Impella guidewire into the left ventricle under a transesophageal echo guidance; (i) advancement of Impella 5.5 pump through the guidewire, the tip of Impella should be placed about 5 cm below the aortic valve and it should point toward the cardiac apex and away from the septal

### **Figure 4.**

*An intraoperative picture of Impella 5.5 insertion into the ascending aorta via a prosthetic graft.*

wall and mitral valve; (j) initiation of Impella 5.5 device; (h) removal of the Impella sheath and trim the graft to the neck incision; and (i) weaning of cardiopulmonary bypass and chest closure. The intraoperative picture is shown in **Figure 4**.

The tips and tricks for this technique are (a) make an adequate length of aortotomy, (b) bevel the graft so that anastomosis can be bigger than the circle area of 10-mm graft, (c) a transesophageal echo guidance (fluoroscopy is not usually necessary), (d) manual manipulation can be used when the Impella pump is passed through the graft anastomosis site, (e) the advancement of Impella could be easier if the blood is returned to the patient from the cardiopulmonary bypass circuit, and (f) do not make the graft length too short, because that would make the future Impella removal difficult.

### **6. Perioperative management of Impella 5.0/5.5**

After the insertion of the Impella, the position of the device should be confirmed routinely with at least two views of transthoracic echocardiography such as parasternal long axis and apical four chamber views. Impella 5.5 does not have a pigtail in the tip as opposed to Impella 5.0. The malposition of the device could easily happen. The device could attach or push the ventricular septum if it is rotated away from the mitral valve and that could cause suction events. The Impella pump needs to be away from the ventricular septal wall. Functional mitral stenosis caused by the dislocation of the device shaft on the anterior mitral leaflet was reported [21]. A big benefit of Impella system through the direct aorta approach is that patients can be extubated and are able to ambulate with Impella system. That can promote patients' quick recovery.

Balthazar and colleagues reviewed the management of mechanical circulatory support [22]. The weaning of Impella should be managed by a multidisciplinary team including cardiac surgeons, cardiologists, intensivists, and perfusionists. Before starting weaning, the patients should have normal lactated levels and on low pressors or inotropes. A daily turndown of the Impella flow with a cautious hemodynamic evaluation should be attempted. When the increase in native cardiac output after weaning of Impella meets the patients' metabolic needs and does not result in significant increases in ventricular pressures, Impella could be removed.

The removal of Impella 5.0/5.5 can be done even with local anesthesia in the intensive care unit. No repeat sternotomy is required. After the Impella is weaned off, the device is pulled out from the graft. The graft is clamped and tied off with heavy silk string or oversewn with monofilament polypropylene sutures. The graft can be closed with surgical staplers. The stump of the graft is put back into the neck incision, and the incision is closed.

### **7. Postoperative outcomes**

The postoperative outcomes of coronary artery bypass grafting with a support of Impella 5.0/5.5 have not been reported frequently. The postoperative outcomes of Impella supported CABG are summarized in **Table 1**. Overall, the reported outcomes have been excellent in consideration of high-risk patients' population.


*Perioperative Use of Impella 5.0/5.5 in High-Risk Coronary Artery Bypass Grafting DOI: http://dx.doi.org/10.5772/intechopen.113370*

### **Table 1.**

*Surgical outcomes of Impella-supported coronary artery bypass grafting.*

### **8. Complications of Impella 5.0/5.5 use**

There are some complications that are specifically related to Impella 5.0/5.5 use. Ghannam and colleagues reported a case of aortic valve injury related to the Impella 5.5 use [32]. The Impella 5.5 was removed on postoperative day 8, and the patient went into cardiogenic shock due to aortic valve leaflet injury, which required aortic valve replacement.

Pump thrombosis is a rare complication, but it has been reported [33]. Systemic anticoagulation with heparin is suggested; however, it can increase the risk of bleeding [34, 35]. Currently, there are no clear data in terms of optimal anticoagulation regimen [36].

Left ventricular perforation could also happen because of the manipulation of the guidewire and cannula into the left ventricle. There were multiple case reports for that [37–41]. Surgeons should suspect left ventricular perforation when there is a newly discovered pericardial effusion, change in waveform on the Impella controller placement signal, or patients' rapid deterioration.

Debenham and colleagues reported adverse events related to Impella 5.0/5.5 in the American College of Cardiology meeting, using the manufacturer and user facility device experience database (the abstract is available at https://www.jacc.org/ doi/epdf/10.1016/S0735-1097%2822%2901478-4). Compared with Impella 5.0, the Impella 5.5 had a higher incidence of pump stoppage (51.7% vs. 10.9%, p < 0.001) and LV perforation (13.3% vs. 1.7%, p < 0.001) with a lower incidence of stroke (0% vs.

8.4%, p < 0.021), mitral valve regurgitation (1.6% vs. 11.8%, p < 0.02), hemorrhage (8.3% vs. 21.8%, p < 0.024), and sepsis (0% vs. 6.7%, p < 0.04). There was no difference in the incidence of vascular injury, limb ischemia, aortic valve damage, pump thrombosis, or hemolysis between the two devices.

The other complications include bleeding, infection, stroke, and acute kidney injury, which are accompanied with usual coronary artery bypass grafting. Since the patient population is sicker than regular patients, the occurrence of complications was reported to be higher than normal.

## **9. Conclusions**

The Impella 5.0/5.5 can be easily inserted into the ascending aorta *via* a prosthetic graft and can provide a tremendous hemodynamic support during and after high-risk coronary artery bypass grafting. It could improve surgical outcomes by avoiding a postoperative low cardiac output syndrome, which is associated with high operative mortality. Direct insertion of an Impella 5.0/5.5 to the ascending aorta allows the patients to ambulate and recover until heart function improves. The explanation of the device is easy and does not require a repeat sternotomy.
