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Novel Modification of Impella Sheath to Prevent Limb Ischemia

Mallikethi-Reddy, Sagar*,†; Khan, Mahin R.*; Khan, Hafiz*; Munir, Ahmad*,†; Moza, Ankush*,†

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doi: 10.1097/MAT.0000000000001584


Over the past decade, the use of percutaneous mechanical circulatory support devices like Impella (Abiomed, Danvers, MA) has increased in patients with cardiogenic shock. Impella is a rotary microaxial pump that serves as a percutaneous alternative to extracorporeal membrane oxygenation (ECMO) or extracorporeal ventricular assist devices. Recently, larger Impella devices have been introduced with peak flows up to 6 L/min. The Impella CP device that is commonly inserted through femoral arterial access through a 14F sheath improves cardiac output with flow rate up to 4 L/min. Large-bore sheaths of Impella devices are associated with an increased incidence of limb ischemia, reported at 4–18%1–3 despite use of repositioning sheath, especially when hemodynamic support is used for prolonged duration (> 24 hours). The repositioning sheath has an outer diameter of 15F at the proximal portion that occupies common femoral artery (CFA). We describe a novel technique to modify 14F Impella sheath in patients with flow-occlusive iliofemoral artery to prevent acute limb ischemia.


Common femoral artery access is obtained using modified Seldinger technique with micropuncture needle under ultrasound and fluoroscopic guidance with an entry angle of < 45 degrees and > 30 degrees between the skin and access needle. Subsequently, a 4F micropuncture sheath is exchanged to a 6F sheath. Next step involves measuring the track depth (TD), which is defined as the distance between skin entry site in the groin to arteriotomy site on the anterior wall of CFA (Figure 1). Track depth can be measured using closure devices such as Angio-Seal (Terumo) or Perclose ProGlide (Abbott Vascular). A 6F Angio-Seal device is slowly advanced over a guidewire, and the skin entry site is marked on the Angio-Seal using a sterile marker pen immediately upon pulsatile blood flow return through the drip hole on the back on end of Angio-Seal device. Undeployed Angio-Seal device is exchanged to a 6F sheath. The distance between marked skin entry site on the Angio-Seal and blood inlet side hole determines the TD that is measured outside the body (Figure 2).

Figure 1.:
Schematic of track depth. CFA, common femoral artery.
Figure 2.:
Measurement of track depth using Angio-Seal device.

Similarly, Perclose ProGlide device is advanced over a guidewire till pulsatile blood flow is seen through the marker lumen on the device. Footplate of the device is opened and gently pulled back until resistance is felt when the footplate is up against anterior wall of the CFA. Site of the Perclose device at the level of skin is marked with a sterile marker pen. Perclose device is exchanged to a sheath. Once outside the body, the footplate of Perclose is opened to measure distance between footplate and marked skin entry site to estimate TD (Figure 3).

Figure 3.:
Measurement of track depth using Perclose Proglide device.

Track depth is now marked on the surface of 14F Impella CP sheath that will be the facing posterior wall of the CFA. A 2.5 mm diameter sterile biopsy punch is used to create two side to side perfusion holes about 5 mm distal to the marked TD on the Impella sheath (Figure 4). Introducer sheath and inner dilator system is advanced over a stiff guidewire and inserted into CFA after serial dilation. Sheath is inserted such a way that the surface of sheath with perfusion holes (dorsal surface) will be facing the posterior wall of CFA.

Figure 4.:
Image of 14F Impella sheath with two perfusion holes on the dorsal surface.

Care should be taken not to create the holes too distal (10 mm beyond TD), as they might abut against the posterior wall of CFA. We suggest adding 5 mm to measured TD while creating holes on the Impella sheath to ensure that perfusion holes are sufficiently within the vessel lumen. Perfusion holes cannot be too shallow (within 2 mm beyond TD), to prevent bleeding into subcutaneous tissue. After the sheath is fully inserted, sheath hub is secured to skin using two criss-cross sutures (see Supplemental Figure 1, Supplemental Digital Content, and a tight dressing to prevent displacement of sheath and its perfusion holes. Ideal placement of the perfusion is confirmed under fluoroscopy using contrast injection through the side arm of 14F sheath. Before pulling the Impella sheath out, a 14F dilator should be inserted inside the sheath over a 0.035” wire to avoid bleeding through perfusion holes. Hemostasis is achieved using standard techniques. Sheath integrity was maintained at the end of case.

Case Report

A 78-year-old female with history of hypertension, diabetes, dyslipidemia, atrial fibrillation, heart failure with reduced ejection fraction, presented with chest pain, 1 mm ST-segment depression in leads V3-V6. Patient had troponin elevation suggestive of non-ST elevation myocardial infarction. Echocardiography showed an left ventricular ejection fraction of 20–25% with global hypokinesis. Coronary angiography revealed severe calcific coronary artery disease involving proximal left anterior descending and right coronary arteries. Angiography of the iliac arteries showed severe tortuosity (see Video 1, Supplemental Digital Content 1, Patient was deemed poor candidate for coronary artery bypass surgery. Hence, high-risk percutaneous intervention was planned. Upon insertion of 14F Impella sheath there was complete cessation of blood flow to the lower limb due to accordion effect from severely tortuous iliac arteries (see Video 2, Supplemental Digital Content 1, Using the aforementioned technique, TD was measured to be 4.2 cm. New sheath was modified by placing two perfusion holes of 2.5 mm diameter on the dorsal surface about 4.7 cm from sheath hub that ensured continuous limb perfusion (see Video 3, Supplemental Digital Content 1, Dorsalis pedal pulse was absent before sheath modification, however, was present after sheath modification. Successful rotational atherectomy guided multivessel percutaneous coronary intervention was performed using Impella CP hemodynamic support without compromising blood flow to the distal limb.


Impella cannula and the motor are larger in size (13F for Impella CP) when compared with Impella catheter shaft, which is only 9F. Hence, the 14F peel-away sheath is used to insert Impella CP device. Upon proper positioning of Impella device in the left ventricle, only a 9F catheter shaft traverses inside the 14F introducer sheath. Our novel technique of sheath modification makes use of the dead space with pool of blood inside 14F peel-away sheath around the 9F Impella catheter shaft. Cross-sectional area (CSA) of 14F peel-away sheath is approximately 17 mm2, while the CSA of 9F Impella catheter shaft is 7 mm2. This leaves around 10 mm2 of dead space around the catheter shaft. We suggest creating two circular holes of 2.5 mm diameter using a sterile punch biopsy needle on the dorsal surface of 14F sheath that would have a summative area of 9.8 mm2. Distal limb perfusion would be preserved through these circular holes in patients requiring prolonged Impella hemodynamic support. Repositioning sheath has an outer diameter of 15F at the proximal portion where it occupies CFA. Since repositioning sheath has only 0.035” free lumen for a guidewire, it cannot be used for making perfusion holes.

Acute myocardial infarction is complicated by cardiogenic shock in up to 8% of patients and carries high mortality rate.1,3 Mechanical circulatory support devices have been increasingly used to support cardiac output and maintain perfusion.1,3 Short-term hemodynamic support using Impella (2.5 and CP) are indicated in cardiogenic shock for up to 4 days. However, limb ischemia is a significant complication of Impella devices, which is seen in 4% to 18% patients.1,2,4 A recent study showed that Impella was associated with an approximately 9% increase in ischemic limb complications when used with venoarterial ECMO as compared to venoarterial ECMO alone in patients with cardiogenic shock.4 Limb ischemia leads to increased healthcare costs, length of hospitalizations, and potentially limb loss.3

Various techniques, such as contralateral femoral external bypass, contralateral femoral internal bypass, ipsilateral femoral external bypass, and ipsilateral radial to femoral external bypass, have been proposed to prevent limb ischemia. However, most of these techniques require maintaining two additional sheaths including an antegrade perfusion sheath. Obtaining antegrade perfusion sheath in superficial femoral artery can be challenging and risky since patients are on systemic anticoagulation. Additional sheaths increase the risk of bleeding, infectious and vascular complications. Unlike in Impella cases, leg ischemia related to ECMO is prevented using routine use of distal perfusion cannula. Our novel technique obviates the need for additional arterial access or sheaths. Similar concept has been employed in LivaNova novel bidirectional perfusion cannula in patients requiring cardiac surgery and ECMO.5 Furthermore, single-access for hi-risk percutaneous coronary intervention technique6 can be safely performed using this modified sheath similar to present case.


Immobilization of the lower extremity is necessary to prevent sheath kinking especially in patients who require prolonged hemodynamic support. Criss-cross sutures at the sheath hub, secure tight dressing on the sheath hub and frequent groin checks would help in preventing and managing sheath related access site complications. It should be noted that making perfusion holes in the sheath usually takes 3 to 5 minutes extra time and there is a learning curve associated with the technique. Femoral arterial access for Impella CP is not recommended if CFA diameter is < 4.7 mm on ultrasound. Since safety data is lacking, operators should be vigilant for sheath disruption during the process of making perfusion holes.


Perfusion holes on the dorsal surface of 14F Impella sheath that lie about 5 mm distal to arteriotomy site of CFA anterior wall maintains continuous limb perfusion via dead space with pool of blood around 9F Impella catheter shaft. Novel sheath modification will be helpful in preventing limb ischemia in cardiogenic shock patients requiring prolonged Impella support if further studies support the safety and efficacy.


1. Pieri M, Sorrentino T, Oppizzi M, et al.: The role of different mechanical circulatory support devices and their timing of implantation on myocardial damage and mid-term recovery in acute myocardial infarction related cardiogenic shock. J Interv Cardiol. 31: 717–724, 2018.
2. Basir MB, Kapur NK, Patel K, et al.; National Cardiogenic Shock Initiative Investigators: Improved outcomes associated with the use of shock protocols: updates from the National Cardiogenic Shock Initiative. Catheter Cardiovasc Interv. 93: 1173–1183, 2019.
3. Kapur NK, Whitehead EH, Thayer KL, Pahuja M: The science of safety: complications associated with the use of mechanical circulatory support in cardiogenic shock and best practices to maximize safety. F1000Res. 9: F1000 Faculty Rev–F1000 Faculty 794, 2020.
4. Schrage B, Becher PM, Bernhardt A, et al.: Left ventricular unloading is associated with lower mortality in patients with cardiogenic shock treated with venoarterial extracorporeal membrane oxygenation: results From an International, Multicenter Cohort Study. Circulation. 142: 2095–2106, 2020.
5. Marasco SF, Tutungi E, Vallance SA, et al.: A phase 1 study of a novel bidirectional perfusion cannula in patients undergoing femoral cannulation for cardiac surgery. Innovations (Phila). 13: 97–103, 2018.
6. Wollmuth J, Korngold E, Croce K, Pinto DS: The Single-access for Hi-risk PCI (SHiP) technique. Catheter Cardiovasc Interv. 96: 114–116, 2020.

Impella; cardiogenic shock; limb ischemia

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