A Procedural Guide for Implanting the Cordella Pulmonary Artery Pressure Sensor

Abstract

Background. The Cordella pulmonary artery (PA) pressure sensor (Endotronix, Inc) is an investigational, wireless, microelectromechanical system (MEMS) sensor that allows remote monitoring of PA pressures. Understanding the implantation procedure and technical nuances is key to safe, efficient, and effective implantation to allow for successful use of the PA pressure sensor over the long term. We provide a summary of the implantation procedure and present a series of cases detailing the Cordella PA pressure sensor implantation in the United States and Europe.

Keywords: heart failure, pulmonary artery pressure sensor, remote patient monitoring

Remote monitoring of pulmonary artery (PA) pressures has been shown to reduce heart failure (HF) hospitalizations in patients with New York Heart Association (NYHA)  class III HF symptoms, regardless of ejection fraction, more effectively than standard HF management.^1-4 The Cordella PA pressure sensor system (Endotronix, Inc) has been shown to enable safe and accurate monitoring of HF patients in the first-in-human SIRONA trial (NCT03375710) and CE-Mark SIRONA 2 trial (NCT04012944) and is currently undergoing further investigation in the PROACTIVE-HF (NCT04089059) investigational device exemption trial.^5-7 The sensor is percutaneously placed exclusively in the right pulmonary artery (RPA), where the interlobar artery typically turns downward and posterior and has a vessel diameter of 12-26 mm (Figure 1).⁸ After implantation, the patient can take daily readings from home via a handheld patient reader placed on the anterior right chest, from either a seated or supine position, and the sensor data are read wirelessly and transmitted automatically to the care team. The reading provides an 18-second measurement of PA pressures, allowing for remote adjustment and optimization of medical therapy to align with prespecified PA pressure goals. The goal of the present review is to provide an overview of the implantation process and present a series of cases highlighting various clinical situations and/or challenges that may arise during sensor implantation.

Implantation procedure. An overview of the system components is shown in Figure 2. The sensor comes preloaded on the distal portion of the catheter-based delivery system with the over-the-wire torque catheter and the delivery catheter incorporates a stability sheath that allows for direct contrast injection without exchange and fluid-filled pressure measurement. The torque catheter has a flexible, soft tip on the distal end connected to a torque handle on the proximal end that can be used to orient the sensor. The sensor body has radiopaque marker dots that assist with the sensor’s orientation under fluoroscopy. Once in position, sensor deployment is achieved by rotating the release wire cap on the torque handle a quarter turn and slowly pulling the release wire cap, then fully removing the release wire. Sensor placement is landmark based within the RPA and is designed to interact with that anatomical segment, fixing it in place and mitigating the risk for sensor dislodgment and/or migration. The sensor location allows for anterior chest readings with a small, hand-held reader while the patient is either seated or supine. The Cordella PA pressure system is contraindicated for patients that cannot tolerate anticoagulation or antiplatelet regimens. The implantation procedure steps are outlined in Table 1 and described below.

Venous access. The implant procedure involves venous access and expansion using a 13-cm x 14-Fr introducer, inserted into either the right femoral vein (RFV) or right internal jugular (RIJ) vein. In particular, the RIJ may be a preferred approach based on physician experience and/or based on patient body habitus or anatomy, history of inferior vena cava (IVC) filter, peripheral venous stents, or artificial valves in the path of a femoral access approach. Left femoral vein (LFV) access has been used successfully for Cordella implantation while left internal jugular (LIF) vein access is not the preferred access for most physicians due to having to traverse the left brachiocephalic vein in order to gain access to the right-sided circulation. Therefore, right-sided access is preferred unless clinically or anatomically contraindicated. Anticoagulation is recommended by heparin with an activated clotting time (ACT) of at least 250 seconds during the implant procedure and the procedure is widely adapted to reversal and closure protocols.

Pulmonary artery access and hemodynamic measurements. Right heart catheterization (RHC) using PA catheter is required to measure baseline hemodynamics of the patient, which include right atrial pressure, right ventricular pressure, PA pressures, pulmonary capillary wedge pressure, and cardiac output, using either the Fick or thermodilution methods. The delivery catheter incorporates a stability sheath that allows for direct contrast injection without exchange and fluid-filled pressure measurement, if needed.

Pulmonary artery vessel mapping. The Cordella PA pressure sensor is implanted in the RPA in the target zone depicted in Figure 1. Using standard catheterization techniques, a Swan-Ganz PA catheter is first positioned at the RPA. In some cases, access to the RPA may be assisted by a guidewire. The target zone diameter must be between 12-26 mm. Quantification of this diameter can be done using quantitative vascular angiography (QVA), catheter features such as the PA catheter balloon size, or radiopaque catheters that allow dimensional estimation. Visualization of the RPA downturn may be achieved by 5-10 mL hand injection of contrast through the PA catheter. Otherwise, the PA catheter may be exchanged for larger catheters such as a pigtail or straight flush catheter and either hand or power injection may be used to visualize the RPA. It is important to ensure the tip of the catheter is proximal to the downturn of the RPA. Once the PA catheter is in position, pulmonary angiography is performed (typically, a hand injection through the PA catheter) in the antero-posterior (AP) and left anterior oblique (LAO) caudal views. Most importantly for optimal visualization, a maximal inspiratory breath hold is performed when obtaining the angiograms. Once the downturn is visualized on the AP view, the target zone is identified along with the posterior right pulmonary distal vessel. As the distal vessels may overlap, the AP and LAO caudal views assist in identifying the largest posterior distal vessel of the RPA. Generally, LAO 30° and caudal 30° are the preferred projections for optimal visualization.

Pulmonary artery guidewire placement. The guidewire (eg, Extra Stiff Amplatz 0.025˝) necessary for the delivery system is positioned in the right lower lobe branch of the RPA at the location of A8-A10 branches (largest posterior descending artery). In Figure 3, multiple catheters (eg, PAC, multipurpose, JR4, 3DRC, etc) may be used to obtain the adequate guidewire position in the A8-A10 branches based on the observed anatomy of the vessels. Ideally, the catheter used to visualize the vessel can be used to wire down the support wire. Other, more flexible, wires are also optional to gain access to the adequate distal vessel, which can then be exchanged to an Amplatz or other stiffer wire. If possible, the support wire should be positioned in the largest posterior vessel distal to the downturn (A8-A10). Use of breath hold for clearer images is recommended during PA access while comparing with the landmark angiography. Once distal access had been achieved with the guidewire in place, wire position should be checked in opposite views (ie, AP and LAO caudal) to confirm appropriate placement.

Sensor preparation and insertion. The delivery system is inspected on the sterile table for damage and the stylet is removed from the distal end. Then, the side port and the guidewire lumen are flushed with sterile saline and the handle is tested to ensure appropriate torque. The delivery system is threaded over the guidewire through the distal tip and inserted through the introducer. Once inserted, the Cordella sensor, attached to the delivery system, is advanced using fluoroscopic guidance over the guidewire through the right heart and positioned in the selected target zone of the RPA, taking care to avoid other medical devices (eg, pacemaker and defibrillator leads) that may be present. During this maneuver, if there is difficulty advancing the delivery system through the heart, one can retract the system 1-2 cm proximally and then apply torque to the handle to rotate the Cordella sensor such that it is on the inner curve of the pathway to the RPA. Once at the target zone, the torque handle should be used to turn the sensor into the anterior-facing orientation, as indicated by the radiopaque sensor marker dots for anterior deployment. Once in target deployment position (distal end of the sensor body at the right interlobar RPA downturn, anterior facing) the release wire cap is turned a quarter turn counterclockwise followed by slow pulling of the release wire cap, deploying the sensor. The release wire should then be pulled all the way out of the delivery system and discarded. Following sensor deployment (Figure 3B), the guidewire is pulled back into the tip of the torque catheter, the delivery system is pulled away from the sensor, and the torque luer is unscrewed to disconnect the luer to allow retrieval of the torque catheter and pulled 2 cm proximal. The wire is pushed inside the torque catheter (to prevent it from catching on the anchors) while the stability sheath should be kept in the pulmonary artery, held in position. Eventually the torque catheter is removed completely, keeping the stability sheath in the PA, proximal to the deployed sensor.

Sensor calibration. The stability sheath can be used as a fluid-filled catheter to obtain a reference pressure by attaching the side port to the pressure transducer. The patient’s chest should be cleared of devices (eg, C-arm, defibrillator pads, electrocardiogram leads, oxygen sensors, monitors, etc), which may potentially cause electromagnetic interfere in order to perform the calibration using the hand-held reader. The transducer signal is captured by the calibration equipment and PA pressures are calculated using the same waveform analysis methods as for the sensor. A manual calibration can also be performed in case the transducer and CalEQ are not compatible by manually inputting the PA pressure values. A single measurement is required in order to calibrate the sensor. Following calibration, the stability sheath should be removed through the introducer. Removal and adequate hemostasis of the 14-Fr introducer should be performed per center protocol.

Post procedure. The patients are educated on the use of their Cordella HF system for home use. The calibration equipment training module provides feedback on the optimal signal strength. Once the training is complete, the reader is set into home mode so it can connect the patient Cordella home kit. Once discharged, the patient’s measurements are sent to the patient management portal for online review by the physician (Figure 4). Patients are advised dual-antiplatelet therapy for the first 30 days; after 30 days, aspirin is continued. For patients with aspirin allergy, other regimens are possible (ie, prasugrel or ticagrelor monotherapy). Patients on long-term oral anticoagulation prior to the implant can continue the same regimen post procedure without the need for dual-antiplatelet therapy for 30 days.

Case Presentations

Case 1. A 74-year-old male with a history of HF with preserved ejection fraction, atrial fibrillation (AF), obesity (body mass index, 38.4 kg/m²), diabetes, chronic kidney disease, and obstructive sleep apnea with multiple hospitalizations for HF exacerbation was referred for Cordella implantation.

The patient was brought to the catheterization lab for a standard implant using right femoral vein access. After performing the right heart catheterization (RHC) and angiography on the RPA, an Amplatz guidewire was placed in the distal RPA branch (A10). Upon inserting the sensor delivery catheter, a moderate resistance was felt by the operator. After further imaging and examining the flow using angiography, a vessel stenosis was detected in the common iliac vein. The patient had no clinical symptoms related to the vein stenosis. Iliac vein compression is a common anatomic variation, and many people have varying degrees of compression of the common iliac vein but have no clinical manifestations.⁹ The vessel stenosis and compression would not allow the sensor to be delivered past the iliac vein segment and the decision was made to attempt the implant via jugular access the next day. The following day, the patient was again brought to the catheterization lab, underwent RHC, RPA angiography, and a guidewire place in the distal RPA via RIJ vein access. The sensor was delivered and deployed without incidence. Total case time was 34 minutes. The patient was ambulating within 30 minutes of the procedure and was discharged home a couple of hours later.

Prior to the presented case, the majority of Cordella implants were completed using femoral vein access with low complication rates comparable to a commercially available PA pressure sensor. Despite many years of using this approach, groin complications remain a significant challenge even when advanced techniques such as ultrasound guidance and micropuncture are employed. Moreover, patient anatomy and/or medical history may pose additional challenges to this technique. As demonstrated in the case presented here, the presence of iliac vein compression prevented femoral access in this case. The IJ access was easily achieved and supported the implantation of the Cordella sensor without challenge. In fact, the anatomy of the RIJ approach formed a “6” as opposed to the more tortuous “S” shape of the femoral approach when traversing the cardiac anatomy (Figure 5). Additional advantages of IJ access include ability to forgo bedrest following the procedure, allowing for faster patient training and discharge, and increasing the throughput in the cardiac catheterization lab, which has potential economic implications.^10,11 Most importantly, by having more techniques to implant the Cordella sensor, more patients can benefit from the next generation remote patient management offered by this system. Of note, the currently used protocol fully supports implanters to choose between the femoral and IJ access sites without issuing protocol deviations or requiring medical necessity for either technique.

Case 2. A 73-year-old male patient with a history of hypertension, coronary artery disease with previous percutaneous coronary intervention, AF, atrioventricular node ablation with pacemaker implant, and multiple cardiovascular hospitalizations was referred for Cordella implantation. The procedure began with 14-Fr introducer to the right femoral vein, followed by the insertion of the PA catheter for RPA access and assessment of baseline hemodynamics. Using a 0.025˝ Amplatz guidewire, the PA catheter was then exchanged for a straight-flush catheter. The initial AP angiography was done using 2-second power injector (10 mL/sec) with free breathing. On this occasion, identification of the downturn and distal mean RPA vessel was difficult and unclear, as the anatomy of the PA was compressed with the diaphragm elevated. Subsequently, the patient was asked to take a deep breath hold during the angiography. As a result, full inspiration lowered the diaphragm in a way that considerably extended the pulmonary vasculature, reducing the vessel tortuosity (Figure 6A and Figure 6B). This led to the clear identification of the downturn and distal RPA vessels, required to identify the target zone and the ideal pathway for the guidewire. Similarly, angiography was taken in LAO caudal with a deep breath hold. The straight-flush and simplified anatomical structure in the deep breath hold configuration assisted with a straightforward pathway to navigate the guidewire in the A9 vessel. With the Amplatz wire in position, the delivery system was advanced to the target zone over the wire. Periodic full inspiration was applied during this implant for better orientation against the roadmap taken under deep breath hold. The soft tip of the delivery system was well positioned in the distal RPA. After checking the marker bands for correct sensor body orientation, the sensor deployed under deep breath hold successfully on the anterior vessel wall. The torque catheter and Amplatz wire were removed and the sensor was calibrated via the stability sheath. The patient underwent training of the system 3 hours after sensor deployment and was discharged home. Figure 6C highlights the significant respiratory variation that was seen for this particular patient.

This case demonstrated the benefit of deep breath hold to identify the anatomical landmarks that assist during sensor implantation, especially for patients with considerable respiratory variation in their PA hemodynamics. The implantation of the Cordella sensor is landmark based and the roadmap with full inspiration led to a level of consistency with anatomy for determining target guidewire location and sensor target zone. Once a landmark angiogram is made with deep breath hold, it remains beneficial to periodically use breath hold when navigating the sensor to the target zone, as well as during sensor deployment to guarantee ideal anatomical orientation assisted by the roadmap. Therefore, deep breath hold is considered an important part of the implantation strategy for the Cordella sensor.

Case 3. The patient was a 48-year-old female with a non-ischemic cardiomyopathy, HF with reduced ejection fraction with a history of hospitalizations for HF exacerbation. Additionally, she was morbidly obese (body mass index, 54.7 kg/m²) and had a history of hyperthyroidism and goiter. She was referred by her cardiologist for Cordella implantation.

The right femoral vein was accessed with a 14-Fr introducer using modified Seldinger technique. RHC was performed with a 7.5-Fr Swan-Ganz catheter. The PA systolic pressure was 68 mm Hg with a mean PA pressure of 42 mm Hg and a mean pulmonary capillary wedge pressure of 18 mm Hg. A 0.025˝ Stiff Amplatz wire (Cook Medical) was positioned in the distal RPA, while doing deep breath holds to facilitate wire positioning. Adequate wire positioning in the A10 position was verified by the downturn shape of the wire in AP view and the downturn medial shape in 30° LAO, 30° caudal view (Figure 7A and Figure 7B).

The Cordella PA pressure sensor was then advanced over the wire proximal to the downturn of the RPA and 10 mL of hand injection via the side port of the Cordella stability catheter was enough to verify correct location of the sensor body prior to deployment of the anchors (Figure 7C). The sensor was successfully deployed (Figure 7D), the wire was withdrawn, and sensor calibration was performed through the stability sheath. Total case time was 61 minutes. Following sensor calibration after sensor deployment, the patient was able to ambulate immediately after the procedure and was discharged home the next day.

Initial cases used power injection with 60-80 mL of contrast to visualize the downturn and the distal vessel to be used as a roadmap for wire and the Cordella PA sensor positioning. This experience showed that the wire positioning in the preferred distal RPA vessels can be verified by a downward shape of the wire in the AP view and a down medial shape in the 30° LAO, 30° caudal view, without requiring angiography with contrast. Minimal amount of contrast (5-10 mL) through the stability sheath by hand injection can be considered to optimize sensor body positioning prior to deployment. The RPA and standard wiring technique allow for such standardization of the implantation, minimizing contrast use (5-10 mL vs 60-80 mL) and associated adverse effects without compromising ease of procedure.

Discussion

Proper implantation of the Cordella PA sensor is the first step toward successful utilization of the Cordella system in remote monitoring and management of patients with HF. High patient and clinic compliance with daily data transmissions, device accuracy and safety, and pressure-guided protocols established and carefully followed are additional key components. The first-in-human SIRONA and CE Mark SIRONA 2 have established that the system enables safe and accurate monitoring.^5,6 The ongoing investigational device exemption trial (NCT04089059), PROACTIVE-HF, is evaluating the use of the Cordella HF management system in 450 New York Heart Association class III HF patients with either 1 previous HF-related hospitalization in the previous year and/or increase in N-terminal-pro-brain natriuretic peptide or brain natriuretic peptide at the time of screening.⁷ In order for patients to gain the benefits of the Cordella HF system, proper implantation is a critical first step.

While the implantation procedure for the Cordella PA sensor is similar to the other PA sensor on the market, the CardioMEMS HF sensor, there are some key differences that should be highlighted.^11,12 The CardioMEMS sensor has a “diameter-based” design and is typically implanted in the left pulmonary artery where anatomy permits.¹³ The Cordella sensor has a “landmark-based” design meant to be deployed in the RPA, as shown in Figure 1, allowing for a standard implant procedure. Furthermore, the Cordella sensor is designed to be implanted opposed to the arterial wall with 2 different anchor mechanisms, designed to interact with the RPA downturn, to allow for increased endothelialization and stability.^14,15 The location of the Cordella sensor in the RPA allows for a short link distance between the implanted sensor and external reader on the anterior chest to allow for front-sided readings with the hand-held reader from a seated position. Additionally, the design of the small anterior reader facilitates the potential for non-invasive PA pressure readings while patients are ambulating and undergoing exercise.

Conclusion

The Cordella HF system is a next-generation complete remote monitoring solution for patients with HF. We describe improved access options, minimal iodinated contrast use, and low procedure times for the Cordella sensor implantation. A major advantage of the Cordella PA pressure sensor is the targeted and consistent placement in the RPA allowing for repeatable daily PA pressure readings from home via a hand-held reader placed on the anterior chest, from either a seated, supine, or ambulating/exercising positions. The Cordella PA pressure sensor is another straightforward option for monitoring PA pressures remotely and easily allows for PA pressure-guided therapeutic changes in high-risk HF patients.

Acknowledgments. We thank Nicholas Hiivala, BME (Endotronix, Inc) for assistance in constructing the manuscript.

Affiliations and Disclosures

From ¹the Department of Medicine, Division of Cardiology, Section for Advanced Heart Failure, Pulmonary Hypertension, and Mechanical Circulatory Support, Prisma Health-Upstate, Greenville, South Carolina; ²Department of Cardiology, Galway University Hospital, Saolta Group, CURAM and BioInnovate Ireland, National University of Ireland Galway, Galway, Ireland; ³Clinical Development, Endotronix, Inc, Lisle, Chicago, Illinois; and ⁴Clinical Development, Endotronix, Inc, Lisle, Chicago, Illinois; and ⁵Division of Cardiology, University of California San Francisco, San Francisco, California.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Forouzan and Dr Martina are employees of Endotronix, Inc. The remaining authors report no conflicts of interest regarding the content herein.

Manuscript accepted September 26, 2022.

Address for correspondence: Liviu Klein, MD, Professor of Clinical Medicine, University of California San Francisco, M-1178B, Box 0124, 505 Parnassus Ave, San Francisco, CA 94143. Email: Liviu.Klein@ucsf.edu

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