PICS~AIC

Authors:Arash Salavitabar, MD and Darren Berman, MD

How I do it: Tips, Tricks, and Techniques

A PICS Society education series

The Use of CardioMEMS™ Implantable Hemodynamic Monitor in Congenital Heart Disease

Introduction:

The CardioMEMS™ HF System (Abbott, Abbott Park, IL) is a FDA-approved implantable hemodynamic monitor that measures pulmonary artery (PA) pressures. The FDA approval has been expanded to patients with NYHA Class II or III heart failure who have either been hospitalized for heart failure in the previous year and/or have elevated natriuretic peptides. CardioMEMS™ implantation has been described in patients with congenital heart disease and heart failure.1-3 The radiopaque device is 15mm long x 3mm wide x 2mm thick (Figure 1) and consists of a coil and capacitor, which forms an electrical circuit that wirelessly transmits PA pressures that are measured via resonant frequency shifts to a remote, web-based system when the patient places an external antenna (embedded within a pillow) underneath his/her back. The sensor anchors within a branch PA via proximal and distal nitinol loops.

Anticipated challenges of the procedure:

CardioMEMS™ implantation is relatively straightforward, however certain underlying patient anatomies can provide challenges. The most common example in the literature is a patient who has undergone an atrial switch operation (Mustard or Senning), which can require tortuous intracardiac catheter turns and thus the use of a long delivery sheath.

TIP 1. Planning and Preparation

1. Access: Femoral or internal jugular vein


2. Imaging: Pre-procedural CTA imaging can be used to understand distal pulmonary artery diameter measurements. The target implant vessel should be within the lower lobe of either lung and in a vessel that is directed posteriorly toward the patient's back. This position is to facilitate communication with the Patient Electronics System, or "patient pillow", on which the patient lays to transmit pressures as an outpatient. According to the CardioMEMS™ IFU, the vessel diameter should be >7 mm where body of sensor will be placed and 5 - 8 mm where the distal loop of sensor will be placed.4 We have found that a distal target diameter of 7-10 mm works well.
   
   
3. Important considerations and reasons for potentially avoiding CardioMEMS™ implantation:

• Inability to tolerate anticoagulation/antiplatelet medication
• Known coagulation disorder
• Active infection
• History of recurrent pulmonary embolism or DVT
• Implantation Loop Recorder (ILR) implantation – An issue with calibration and pressure transmissions from home has been documented in a patient with an ILR, which resolved upon ILR removal.³ More data are needed to understand whether this is a true contraindication or whether CardioMEMS™ implantation should simply be performed in the contralateral branch PA to avoid proximity to the ILR.

Tip 2. Tools needed

1. Sheaths: The device delivery system fits through a 12-French sheath, however it can be delivered through an 11-French Terumo Pinnacle sheath (Terumo Medical Corporation, Somerset, NJ).


2. Catheters:  Balloon wedge catheter to obtain wire position


3. Devices: CardioMEMS™ device and catheter, In-hospital calibration system


4. Other: Interventional (stiff) 0.018" wire, 12-French long sheath if desired for angiography and/or to assist in tracking the device in a patient with tortuous course (e.g., atrial switch post-operative anatomy)

Tip 3. How I do it

1. Details of the individual tip and technique:

• Standard biplane angiography is utilized to identify a target vessel (Video 1a & 1b). A 0.018" interventional wire is anchored within the target branch. The sensor is rinsed in sterile saline for 30-60 seconds. Either directly over the wire or via a long sheath, the device is advanced to the target vessel. The blue screw (Figure 1c) is loosened, which releases the nitinol loops from an inner cord that runs through the delivery system (Video 2a & 2b). Calibration is performed using the "calibration wand" (Figure 2a & 2b), which is placed under the patient's back while simultaneously measuring a direct PA pressure within the same vessel as the sensor (Figure 2c &2d). A post-implantation angiogram can be performed to confirm final device position (Video 3a & 3b).


• Please see figures, link to videos with Figure legends

2. Pitfalls to avoid

• As mentioned above, target vessel diameter is important. Device instability has been found to be associated with larger target vessel diameters in patients with CHD (12.8 ± 1.0 mm vs. 8.6 ± 1.4 mm, p = .01)³.


• While a long sheath is often helpful in navigating the tortuous course of an atrial switch anatomy, this can sometimes complicate the procedure if there are stents and pacing leads in the way. It is often feasible to deliver the sensor directly over the wire and through a short sheath using landmarks for the target vessel.

Tip 4. What complications to expect and how to deal with them

• Device embolization

This device has rare reports of embolization to the contralateral branch pulmonary artery.^3,5 If PA pressures can be transmitted appropriately, no action is needed. Proper retrieval through an endovascular sheath has not been described but should be feasible. This could be accomplished with a snare and large bore sheath or with the recent FDA approved ONO retrieval basket (ONOCOR; Philidalphia, PA).

• Incomplete release

The sensor can be incompletely free of the delivery catheter and wire after release.³ In this situation, removal of the delivery catheter can result in proximal movement of the device.  A directional catheter can be advanced through the sheath, adjacent to the wire, and used to stabilize the device as the catheter and wire are withdrawn.

• Device Dislodgement while removing distal wire

Once released and the delivery catheter has been removed, one must still remove the 0.018" wire. The distal wire could interact with the device and dislodge the device proximally. To avoid this rare event, be careful to not place a large J-shaped curve on the soft end of the distal wire. One can also consider using a soft straight Nitinol tipped wire so that it slides past the device easily upon removal or anchoring the device with a directional catheter while retracting the wire.

Summary:

CardioMEMS™ sensor implantation is feasible and safe in patients with complex congenital heart disease and amenable distal pulmonary vasculature. This can be performed through a short sheath or with the assistance of a long sheath. Delivery of the sensor is very intuitive but may require additional techniques to avoid sensor movement following release in some cases. The sensor can be quickly calibrated to directly measured invasive pulmonary artery pressures and used for outpatient hemodynamics as needed.

References:

1. Bradley EA, Berman D, Daniels CJ. First implantable hemodynamic monitoring device placement in single ventricle Fontan anatomy. Catheter Cardiovasc Interv. 2016;88:248-252. https://doi.org/10.1002/ccd.26498.
2. Bradley EA, Jassal A, Moore-Clingenpeel M, Abraham WT, Berman D, Daniels CJ. Ambulatory Fontan pressure monitoring: results from the implantable hemodynamic monitor Fontan feasibility cohort (IHM-FFC). Int J Cardiol. 2018;284:22-27. https://doi.org/10.1016/j.ijcard.2018.10.081.
3. Salavitabar A, Bradley EA, Chisolm JL, et al. Implantable pulmonary artery pressure monitoring device in patients with palliated congenital heart disease: Technical considerations and procedural outcomes. Catheter Cardiovasc Interv. 2019;1–10. https://doi.org/10.1002/ccd.28528.
4. St. Jude Medical I. CARDIOMEMS™ HF System PA sensor and delivery system product highlights. Retrieved from https://www.sjm.com/en/professionals/resources-and-reimbursement/technical-resources/cardiac-rhythm-management/heart-failure-monitoring-system/pa-pressure-monitoring/cardiomems-hf-system-pa-sensor-and-delivery-system?clset=af584191-45c9-4201-8740-5409f4cf
5. Rali AS, Shah Z, Sauer A, Gupta K. Late migration of a CardioMEMS™ wireless pulmonary artery hemodynamic monitoring sensor. Circ Hear Fail. 2017;10(4):e003948. https://doi.org/10.1161/circheartfailure.117.003948.

 

figures

Figures with legends:

 

 

 

 

Biplane transcatheter angiography to identify the target vessel in a patient with a Fontan operation.

 

Release of the sensor with the distal left pulmonary artery.

 

Post-implantation angiogram confirming final device position.

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