Dysfunctional Implantable Pulmonary Artery Sensor Device (CardioMEMS) in Group 2 Pulmonary Hypertension

Abstract

Implantable hemodynamic devices like the CardioMEMS HF System are commonly used to manage fluid status in patients with heart failure (HF) by measuring pulmonary pressures. Although CardioMEMS has been shown to reduce HF hospitalizations, rare complications (eg, device endothelialization) can occur and warrant clinical attention. A 67-year-old woman with HF with preserved ejection fraction and group 2 pulmonary hypertension experienced recurrent HF exacerbations. Despite optimal therapy, she was not a candidate for advanced HF therapies. The CardioMEMS device, initially effective for fluid management, showed dampened waveforms due to endothelialization, leading to reimplantation. Endothelialization is a rare but significant complication that can dampen pressure waveforms. Proper placement in vessels larger than 7 mm and careful monitoring of waveforms can help manage this issue. Device recalibration can usually address most cases; however, reimplantation may be required.

Graphical Abstract

A 67-year-old woman with multiple admissions for heart failure (HF) exacerbation and volume overload was evaluated for advanced therapies. Right heart catheterization (RHC) showed a pulmonary capillary wedge pressure (PCWP) of 25 mm Hg, pulmonary vascular resistance (PVR) of 8 WU, and mean pulmonary arterial pressure of 52 mm Hg. Cardiopulmonary exercise testing indicated a peak oxygen uptake of 8 mL/kg/min. Pulmonary function tests revealed severely reduced forced vital capacity and forced expiratory volume in 1 second, consistent with both obstructive and restrictive processes. Echocardiography revealed a normal left ventricular ejection fraction of 55% and a flattened interventricular septum, consistent with pressure overload. There was mild tricuspid regurgitation, with an estimated pulmonary artery (PA) systolic pressure of 75 mm Hg based on the tricuspid regurgitation signal.

Take-Home Messages

• •CardioMEMS is a valuable tool in managing heart failure, and complications like endothelialization are rare.
• •Ensuring proper device placement in a large vessel and careful monitoring of waveforms can help mitigate such risks.
• •Recalibration is often sufficient, but reimplantation may be needed in exceptional cases.

A multidisciplinary team, including adult congenital heart disease, pulmonary hypertension, and advanced HF experts, concluded that the patient was not a candidate for a heart transplant due to prohibitive combined pre- and postcapillary group 2 pulmonary hypertension (Cpc-PH). Left ventricular assist device was deemed unsuitable because of normal systolic function and a small left ventricular cavity. Thus, the only viable option was medical therapy with diuresis guided by the CardioMEMS HF System (Abbott). The device was implanted in an 8-mm PA branch vessel, and its waveforms correlated well with the invasive waveforms from the Swan-Ganz catheter at the time of implantation. After aggressive diuresis and afterload reduction therapy, repeated RHC showed right atrial pressure of 11 mm Hg, right ventricular pressures of 79/7/12 mm Hg (systolic/diastolic/mean), PA pressures of 77/37/49 mm Hg, and PCWP of 19 mm Hg. CardioMEMS readings were consistent with RHC findings (Figures 1 and 2). Her volume status was managed based on CardioMEMS readings using torsemide and metolazone as needed, whereas heart failure with preserved ejection fraction (HFpEF) was treated with spironolactone, empagliflozin, and afterload reduction.

Figure 1.

Comparison of Pulmonary Artery Waveforms Showing the First (Failed) and Second (Successful) CardioMEMS Devices

(A) Pulmonary artery tracing during right heart catheterization for the first CardioMEMS device implantation. The lower panel shows CardioMEMS tracing correlated with pulmonary artery (PA) readings obtained using a PA catheter. (B) PA tracing during right heart catheterization for the second CardioMEMS device implantation. The lower panel shows CardioMEMS tracing correlated with PA readings obtained using a PA catheter. PAP = pulmonary artery pressure.

Figure 2.

Cine Angiogram of Target Left Pulmonary Artery Location for CardioMEMS Device

(A) Selective cine angiogram of the left pulmonary artery showing a suitable target location for the CardioMEMS device. (B) Selective cine angiogram of left pulmonary artery branches demonstrating a borderline target for the second CardioMEMS device.

Two years later, we noticed that CardioMEMS pressure waveforms were dampened and inconsistent with the clinical picture despite multiple attempts to recalibrate the device. At this point, the team opted not to rely on the CardioMEMS readings and instead managed the patient’s volume status based on clinical judgment. During this period, the patient was admitted 3 times within 2 months for HF or acute kidney injury due to fluid overload or dehydration, respectively (Figure 3).

Figure 3.

Illustration of Dampened PA Pressure Tracing of Malfunctioning and Functional CardioMEMS Device

(A) First CardioMEMS readings over time, indicating dampened pulmonary artery tracings with gradual dampening over time. The black arrow highlights a snapshot showing dampened waveforms. (B) Second CardioMEMS waveform tracing functioning properly. PA = pulmonary artery.

Past Medical History

She has partial Shone's complex and underwent surgical repair of coarctation at 27 years of age, which was complicated by partial vocal cord paralysis. She has mild mitral stenosis due to a parachute mitral valve, a history of infective endocarditis on the mitral valve treated medically, and HFpEF with subsequent Cpc-PH. Additionally, she has paroxysmal atrial fibrillation treated with ablation and dofetilide therapy, along with chronic anticoagulation. She has experienced a bradycardic cardiac arrest, leading to pacemaker implantation. She also has depression, anxiety, and moderate pectus excavatum. She has no history of chronic kidney disease or diabetes and has a BMI of 19 kg/m².

Differential Diagnosis

The differential diagnosis for dampened CardioMEMS pressure waveforms includes the following: 1) device migration: migration can result in inaccurate pressure readings, interfering with appropriate management; 2) CardioMEMS sensor failure: a malfunction of the sensor can lead to incorrect pressure readings; 3) pulmonary embolism and thrombus formation: these conditions can decrease blood flow to the vessel, affecting pressure readings; and 4) device endothelialization: tissue overgrowth on the CardioMEMS sensor can dampen waveforms and cause inaccurate pressure measurements.

Investigations

The CardioMEMS reading was dampened at 58/50/53 mm Hg, whereas the same-day RHC showed PA pressures of 44/20/32 mm Hg, a normal right atrial pressure of 5 mm Hg, and mildly elevated right ventricular pressures of 48/3/14 mm Hg. The cardiac index was 4.4 L/min/m², and PVR was normal at 2.56 WU. Selective right PA cine-angiography revealed that the CardioMEMS device was completely endothelialized within the PA branch, preventing proper capture by the external receiver.

Management

An attempt to recalibrate the CardioMEMS device during RHC was made, but the readings still did not correlate with the clinical picture. Eventually, the decision was made to abandon the use of this CardioMEMS sensor, and because the patient was not a candidate for advanced HF therapies, implantation of a newer CardioMEMS device was considered. Left PA branch showed a borderline caliber vessel of 7 mm, pulmonary hypertension with a mean PA pressure of 45 mm Hg, PCWP of 19 mm Hg, and PVR of 6 WU. The new CardioMEMS device was successfully implanted in the left pulmonary artery (Figures 1 and 2). Since then, the patient’s fluid status has been managed successfully using readings from the new CardioMEMS device, with the last reading showing a diastolic pulmonary pressure of 30 mm Hg (Figure 4).

Figure 4.

Fluoroscopic Image Showing the Position of the 2 CardioMEMS Devices

Discussion

Implantable hemodynamic devices (eg, CardioMEMS HF System) are increasingly used in patients with HF to manage fluid status by directly measuring pulmonary pressures. Adjusting diuretic doses in response to elevated pulmonary pressures detected by CardioMEMS can prevent fluid overload and congestion, reducing the risk of HF hospitalization. Studies have shown that CardioMEMS significantly decreases HF hospitalizations and, according to a recent meta-analysis, also reduces mortality.1, 2, 3 Since Food and Drug Administration approval in 2014, the indications for CardioMEMS use have expanded to include patients with NYHA functional class II or III HF who have either been hospitalized for HF exacerbation within the past year or have elevated levels of natriuretic peptides.⁴ The device is peripherally inserted via a catheter into a PA branch and calibrated in real time with Swan-Ganz catheter.⁴ It is monitored remotely at home using an electromagnetic receiver that transmits data. Ensuring proper vessel sizing and precise device placement is crucial to secure its position within the PA branch. Distal placement can result in the sensor becoming overly endothelialized, leading to signal loss or dampening, while proximal placement risks device migration.⁴

In a postmarketing outcome study by Vaduganathan et al,⁵ 155 adverse events (2.8%) were reported out of 5,500 CardioMEMS implants. There were 46 cases of sensor failure, malfunction, or migration. Of these, 35 required recalibration, and 13 needed reimplantation. Only 5 sensors remained unusable even after recalibration. The characteristics of these reimplantation cases were not reported.

Benza et al⁶ reported using the CardioMEMS device in 26 patients with pulmonary arterial hypertension (World Health Organization group I). These patients were followed for an average of 2.5 ± 1.4 years with no adverse events reported, including no instances of device endothelialization or migration. Potential risk factors for dampened CardioMEMS waveforms due to endothelialization include distal implantation, undersizing of the target vessel, and thrombosis or embolization.⁷ It has been reported that gradual changes in CardioMEMS waveforms can occur over time due to sensor drift, with an estimated rate of 0.1 mm Hg per year.⁸ After excluding technical factors, dampened waveforms can often be resolved by confirming the diagnosis with RHC and recalibrating the sensor. In most cases, these measures are successful.⁸

We reported a case of CardioMEMS device failure due to complete endothelialization in a patient with HFpEF and severe Cpc-PH. This failure may be attributed to tissue overgrowth, endothelial hyperactivity, and relatively distal implantation.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.