Short-term right ventricular or biventricular mechanical circulatory support: Use of echocardiography during initiation and management

INTRODUCTION — Temporary short- and intermediate-term mechanical circulatory support (MCS) devices for left ventricular (LV), right ventricular (RV), or biventricular support may be used for patients with cardiogenic shock or cardiorespiratory failure when medical therapy has failed. This topic addresses the role of transesophageal echocardiography (TEE) imaging during short-term MCS for the RV (eg, to guide insertion of the device and positioning of the inlet and outlet ports, monitor device function, and facilitate eventual weaning from the device). This topic also addresses the role of TEE in managing biventricular support.

Other topics address:

●Use of TEE to guide insertion, positioning, and initial functional assessment of short-term devices for MCS of the LV – (See "Short-term left ventricular mechanical circulatory support: Use of echocardiography during initiation and management".)

●Use of TEE imaging to facilitate initiation, monitoring, and weaning of extracorporeal membrane oxygenation (ECMO) – (See "Extracorporeal life support in adults in the intensive care unit: The role of transesophageal echocardiography (TEE)".)

Indications, device selection, and general management of patients who require short-term LV and/or RV MCS are addressed in a separate topic. (See "Short-term mechanical circulatory assist devices".)

OVERVIEW OF RV SUPPORT — MCS devices can provide short-term right ventricular (RV) support by pumping blood from the inferior vena cava (IVC), superior vena cava (SVC), or right atrium (RA) to the pulmonary artery (PA), thereby bypassing the RV [1]. Such support can unload the RV, ensure adequate left ventricular (LV) preload, and optimize end-organ perfusion after failure of optimal medical therapy for severe RV dysfunction (eg, inotropic agents such as dobutamine, epinephrine, or milrinone; optimization of volume status to ensure adequate filling while avoiding overdistension; maintenance of coronary perfusion pressure; and reduction of RV afterload with inhaled or intravenous pulmonary vasodilators). (See "Short-term mechanical circulatory assist devices", section on 'Right ventricular assist devices'.)

Temporary support of the RV in isolation or in addition to MCS of the LV may be necessary due to:

●RV pressure overload resulting from advanced LV failure, pulmonary hypertension, or acute pulmonary embolus

●RV volume overload resulting from right-sided cardiac valve insufficiency or a left-to-right shunt

●Decreased contractility of the RV after acute myocardial infarction or myocarditis

●RV failure after placement of a durable LV MCS device

●Postcardiotomy shock following inadequate myocardial protection during a cardiac surgical procedure or after heart transplantation (see "Intraoperative problems after cardiopulmonary bypass", section on 'Right ventricular dysfunction')

ECHOCARDIOGRAPHY BEFORE INITIATING RV SUPPORT — Transesophageal echocardiography (TEE) or transthoracic echocardiography (TTE) is useful before initiating short-term MCS for the right ventricle (RV) in order to [2]:

●Confirm the presumed diagnosis and need for an MCS device to support the RV.

●Determine whether abnormalities that may contraindicate device placement or interfere with device function are present. Examples include:

•Thrombi or other masses in the right atrium (RA) (movie 1), RV, or pulmonary artery (PA) that may impede cannula drainage or flow.

•Stricture or thrombus in the superior vena cava (SVC) or inferior vena cava (IVC) that may preclude placement of the device or impede adequate venous drainage. Detection of turbulent or flow acceleration using color-flow Doppler (CFD) indicates such a stricture.

•Presence of an IVC filter or congenital condition causing interruption of the IVC [3].

•An intracardiac shunt such as a large patent foramen ovale (PFO) (movie 2) or atrial septal defect (ASD) (movie 3) may cause significant left-to-right shunting when the RA is unloaded. Thrombus formation on any intravascular or intracardiac cannula may lead to a stroke if right-to-left transit via a PFO occurs.

•Severe stenosis of the tricuspid or pulmonic valve, or presence of a mechanical prosthetic tricuspid or pulmonic valve. These factors preclude placement of a percutaneous device such as the Impella right percutaneous (RP) device or a ProtekDuo cannula.

•Pulmonic regurgitation. Presence of more than mild pulmonic regurgitation may lead to recirculation limiting the efficacy of device output delivered to the main PA. However, tricuspid regurgitation is typically well tolerated during support of the RV with an MCS device.

PROCEDURES FOR INSERTION OF SPECIFIC RV SUPPORT DEVICES — Percutaneous placement of MCS devices enables rapid deployment of right ventricular (RV) support without need for surgery. Device selection depends on the specific indication for hemodynamic support, the setting, the urgency of need, and patient- or device-related risks and contraindications, as well as institutional experience with specific device(s). (See 'Overview of RV support' above and "Short-term mechanical circulatory assist devices", section on 'Right ventricular assist devices'.)

Three RV assist devices (RVADs) are percutaneously inserted: The Impella right percutaneous (RP) device, the Impella RP Flex device, and the ProtekDuo catheter coupled with an extracorporeal centrifugal pump (table 1). These devices bypass a failing RV by pumping blood into the pulmonary artery (PA) from the right atrium (RA), inferior vena cava (IVC), or superior vena cava (SVC).

An alternative is surgical placement of the RVAD via central cannulation of the RA (inflow cannula) and the PA (outflow cannula). The cannulae are connected to an extracorporeal continuous flow centrifugal blood pump such as the CentriMag or Rotaflow. This technique of central cannulation for temporary RV support is generally used to treat postcardiotomy shock or if a patient exhibits severe RV failure after placement of a durable left ventricular assist device (LVAD).

Impella RP device

Overview of the Impella RP device — The Impella RP microaxial flow pump for RV support is placed via the femoral vein. The inlet port is positioned at the IVC cavoatrial junction, and the distal outlet (return) cannula opening is located near the tip of the catheter positioned within the main PA beyond the pulmonic valve [4-6]. Thus, the microaxial pump located inside the catheter is able to drain blood from the IVC and pump it into the PA.

The Impella RP catheter can produce flow rates up to 5.0 L/minute [7] and provide temporary RV support for up to 14 days in patients with body surface area ≥1.5 m².

Imaging during insertion of the Impella RP device — Placement of the Impella RP via a femoral venous approach is typically achieved using both fluoroscopy guidance and transesophageal echocardiography (TEE) confirmation. Proper positioning of the inlet port at the IVC cavoatrial junction is confirmed with a modified midesophageal (ME) bicaval TEE view that identifies the junction of the IVC and the RA. Proper positioning of the outlet port in the main PA is confirmed in an ME RV inflow-outflow view or upper esophageal (UE) aortic arch short-axis (SAX) TEE view [6,8].

Final proper positioning of the device is confirmed by noting the position of the device outlet in the main PA below the PA bifurcation and not engaging the main PA branches, so that flow is not preferentially delivered to one side over the other. A mosaic pattern of turbulent blood flow from the outlet port is demonstrated in the main PA using color-flow Doppler (CFD) imaging.

Impella RP Flex device

Overview of the Impella RP Flex device — Similar to the positioning of the ProtekDuo cannula (see 'Imaging during insertion of the ProtekDuo cannula' below), the Impella RP Flex with Smart Assist is designed to be implanted via the right internal jugular (IJ) vein for up to 14 days to treat acute right heart failure.

Imaging during insertion of the Impella RP Flex device — The inlet port is positioned at the superior cavoatrial junction. The outflow (return) port is located at the tip of the catheter and positioned within the main PA beyond the pulmonary valve. The microaxial pump located within the catheter draws blood from the superior cavoatrial junction and expels the blood in the PA bypassing the RV.

ProtekDuo cannula for RV support

Overview of the ProtekDuo cannula — Similar to the Impella RP Flex device (see 'Impella RP Flex device' above), the ProtekDuo cannula is a dual-lumen coaxial cannula that is positioned via the IJ vein (or the left subclavian vein). The inlet of the device sits at the junction of the RA with the SVC, while its distal tip (outlet) is positioned beyond the pulmonic valve within the main PA. The cannula is coupled with an extracorporeal centrifugal pump such as the TandemHeart, CentriMag, or Rotaflow pump. An oxygenator can be added to the circuit to also provide oxygenation in selected patients. (See "Short-term mechanical circulatory assist devices", section on 'Right ventricular assist devices'.)

Imaging during insertion of the ProtekDuo cannula — TEE is used to guide cannula insertion into the SVC via the right IJ vein or the left subclavian vein. The inlet port should be positioned at the superior cavoatrial junction. The cannula then traverses the tricuspid valve and pulmonic valve so that the distal tip for blood return (outlet) is positioned in the main PA. If the distal tip is in the right or left PA rather than the main PA, the cannula should be withdrawn to avoid overperfusion of one lung.

Central temporary RV support

Overview of central RV support — Similar to central support for the LV (see "Short-term left ventricular mechanical circulatory support: Use of echocardiography during initiation and management", section on 'CentriMag device for LV support'), extracorporeal centrifugal pumps, such as CentriMag and Rotaflow, may be used for temporary central RV support. Typically, the patient is undergoing cardiac surgery and experiences postcardiotomy shock, or RV failure becomes evident after implantation of a durable LVAD. Central (nonpercutaneous) cannulation is accomplished either through a sternotomy or via a left thoracotomy, with direct insertion of the inflow cannula into the RA. The outflow cannula may be inserted into the PA either directly or through a graft attached to the main PA, through which the device outflow cannula is passed [9,10]. Alternatively, the inflow cannula can be inserted in the RA percutaneously via femoral venous cannulation.

Imaging during cannula insertion for central RV support — TEE is used to guide insertion of the inflow and outflow cannulae for central RV support with a centrifugal pump.

●Inflow cannula

•Centrally inserted inflow cannula – For central insertion, the atrial inflow cannula is placed anteriorly at the level of the RA appendage. It is best visualized in the ME modified bicaval view to identify its location in the RA, as well as orientation and depth of insertion. Both two-dimensional and CFD imaging should be used to ensure correct position of the cannula. Its tip should not be touching the walls of the RA or cavae, and laminar flow into the cannula tip is documented. While spectral Doppler can be employed to measure blood flow velocities, there are no recognized velocity guidelines, thereby limiting the utility of these measurements.

Very rarely, the inflow cannula may be inserted into the RV. Both the ME four-chamber view and ME RV inflow-outflow view can be used to visualize the cannula in this configuration.

•Femoral venous inflow cannula – If the RA inflow cannula is placed percutaneously via femoral venous cannulation, the presence of the guidewire should be observed as it is advanced from the IVC into the RA. Subsequently, the cannula is observed advancing over the wire in the RA. Final placement should be with the opening of the cannula mid-RA or close to the superior cavoatrial junction.

●Outflow cannula – The outflow cannula is implanted at the level of the main PA. Visualization of this cannula can be achieved in the UE aortic arch SAX view, the ME ascending aorta SAX view, or a modified ME RV inflow-outflow view. The cannula should not be touching the walls of the main PA. Also, to avoid preferential flow to one lung, the outflow cannula should not be directed unilaterally toward either the left or right PA.

ECHOCARDIOGRAPHY TO MONITOR RV SUPPORT — Transesophageal echocardiography (TEE) may be used to troubleshoot problems with function of any of the devices for right ventricular (RV) support discussed in this topic. These include [6]:

●Inadequate flow due to:

•Hypovolemia.

•Presence of clot partially occluding the inlet or outlet.

•External compression of RV chambers by the accumulation of clot or pericardial effusion. Careful TEE examination in multiple views is necessary to rule out the possibility of loculated effusion(s).

●Inadequate decompression of the RV despite normal pump flow. This may occur due to migration of the distal tip of the device below the pulmonic valve into the RV outflow tract. In this situation, the device should be advanced and repositioned under echocardiographic or fluoroscopic guidance.

ECHOCARDIOGRAPHY DURING WEANING AND REMOVAL OF RV SUPPORT

●Echocardiography during weaning from right ventricular (RV) support – During weaning of RV support, myocardial recovery can be evaluated with transesophageal echocardiography (TEE) or transthoracic echocardiography (TTE) in conjunction with monitoring of hemodynamics. There are limited data to guide weaning from temporary MCS for the RV. Generally, the level of support is gradually decreased in 0.5 to 1.0 L/minute increments approximately every two to three hours [5]. Indicators of readiness to wean and explant the MCS device include improved right-sided hemodynamics with central venous pressure (CVP) <12 mmHg and mixed venous oxygen saturation >55 percent, as well as qualitative improvement of RV systolic function on TEE or TTE examination at lower levels of MCS support [11].

After removal of percutaneously inserted cannulae and RV support device, a complete TEE or TTE examination is performed to document the new "baseline" functions of the left ventricle (LV) and RV and to assess whether iatrogenic tricuspid or pulmonic valve injury occurred during device insertion, use, or removal [12].

●TEE during removal of cannulae for central RV support – Removal of some percutaneously inserted temporary RV support devices and all centrally inserted cannulae is accomplished in the operating room (similar to removal of a centrally inserted LV support device). (See "Short-term left ventricular mechanical circulatory support: Use of echocardiography during initiation and management", section on 'CentriMag device for LV support'.)

This may occur due to recovery of RV function or for more definitive treatment (eg, heart transplantation, insertion of a durable LV assist device [LVAD], palliative care). Intraoperative TEE is subsequently used to assess ventricular function of the native heart in the absence of support, or the donor heart after transplantation.

TEMPORARY BIVENTRICULAR SUPPORT

Overview of biventricular support — Presence of biventricular failure prompts consideration of initiating venoarterial extracorporeal membrane oxygenation (ECMO) (table 2) or placement of biventricular MCS devices. (See "Short-term mechanical circulatory assist devices".)

Biventricular support can be achieved through various configurations of devices:

●Two surgically implanted temporary left ventricular (LV) and right ventricular (RV) MCS devices.

●Two percutaneous devices for temporary MCS of both ventricles. Examples include:

•Impella device for LV support coupled with Impella right percutaneous (RP) device for RV support

•TandemHeart centrifugal pump for LV support coupled with a ProtekDuo dual-lumen cannula inserted to provide RV support

●Addition of a percutaneous RV MCS device to a previously implanted durable LV assist device (LVAD).

Imaging during support and weaning of devices

●Use of imaging to monitor support – For biventricular support, either transesophageal echocardiography (TEE) or transthoracic echocardiography (TTE) monitoring is critical to manage device flows and achieve balance between right and left circulations. Inadequate RV mechanical support can lead to underfilling of the MCS device on the left side, with reduced systemic output and inadequate end-organ perfusion. On the other hand, excessive flow from the MCS for RV support can lead to pulmonary complications including pulmonary edema and hemoptysis caused by pulmonary circulation overload.

Unique echocardiographic considerations for biventricular support include assessment of [13]:

•Position of the interventricular septum and interatrial septum. Ideally, both septae are midline (indicating a balanced circulation).

•Relative size of the LV and RV chambers.

•Degree of decompression of the LV and RV, noted by assessing the change in severity of mitral and/or tricuspid regurgitation, as well as the frequency of aortic valve and pulmonic valve opening with initiation of support.

●Use of imaging during weaning of biventricular support – In some cases, TEE or TTE is used to assess readiness to wean and explant LV and RV MCS if it has been possible to reduce levels of support. However, biventricular support is usually a bridge to other support, such as heart transplantation or surgical insertion of a durable LVAD when RV function has adequately recovered, or serves as a bridge to palliative care [11].

SUMMARY AND RECOMMENDATIONS

●Overview of right ventricular (RV) support – Short-term mechanical circulatory support (MCS) devices for the RV pump blood from the inferior vena cava (IVC), superior vena cava (SVC), or right atrium (RA) to the pulmonary artery (PA), thereby bypassing the RV. After failure of optimal medical therapy for severe RV dysfunction, such MCS can unload the RV, ensure adequate left ventricular (LV) preload, and optimize end-organ perfusion. (See 'Overview of RV support' above.)

●Echocardiography before initiating RV MCS – Transesophageal echocardiography (TEE) or transthoracic echocardiography (TTE) is useful to confirm the presumed diagnosis and need for RV support, and to identify any abnormalities that may contraindicate device placement or interfere with device function. Examples include thrombi or other masses in the RA or PA, strictures or thrombi in the SVC or IVC, significant intracardiac shunting (eg, atrial septal defect [ASD], ventricular septal defect, patent foramen ovale [PFO]), or severe tricuspid valve or pulmonic valve stenosis or regurgitation. (See 'Echocardiography before initiating RV support' above.)

●Insertion of Impella right percutaneous (RP) device – The Impella RP pump is placed via the femoral vein using both fluoroscopy guidance and TEE confirmation of proper positioning of the inlet port at the IVC cavoatrial junction. The distal outlet (return) cannula opening is located near the tip of the catheter positioned within the main PA beyond the pulmonic valve. Thus, the microaxial pump located inside the catheter is able to drain blood from the IVC and pump it into the PA. A mosaic pattern of turbulent blood flow from the outlet port is demonstrated in the main PA using color-flow Doppler (CFD) imaging. (See 'Impella RP device' above.)

●Insertion of Impella RP Flex device – The Impella RP Flex with Smart Assist is implanted via the right internal jugular (IJ) vein using both fluoroscopy guidance and TEE confirmation of proper positioning of the inflow port of the superior cavoatrial junction and the outlet port within the main PA. A mosaic pattern of turbulent blood flow is demonstrated using CFD imaging. (See 'Impella RP Flex device' above.)

●Insertion of ProtekDuo cannula – The ProtekDuo cannula is a dual-lumen coaxial cannula positioned via the IJ (or the left subclavian vein) with TEE guidance, with its inlet at the junction of the RA with the SVC, while its distal tip (outlet) is positioned beyond the pulmonic valve within the main PA. The cannula is coupled with an extracorporeal centrifugal pump such as the TandemHeart, CentriMag, or Rotaflow pump. An oxygenator can be added to the circuit. (See 'ProtekDuo cannula for RV support' above.)

●Central temporary RV support – (See 'Central temporary RV support' above.)

•Inflow cannula insertion – For central insertion of the RA inflow cannula, placement is anterior at the level of the RA appendage.

If the RA inflow cannula is placed percutaneously via femoral venous cannulation, the presence of the guidewire is observed advancing from the IVC into the RA, then over the wire in the RA, with final positioning at the opening of the cannula mid-RA or close to the superior cavoatrial junction.

•Outflow cannula insertion – The outflow cannula is implanted at the level of the main PA and should not be directed unilaterally toward either the left or right PA.

●Echocardiography to monitor RV support – TEE may be used to troubleshoot reasons for inadequate flow (eg, hypovolemia, presence of clot partially occluding the inflow or outflow cannulas, external compression of RV chambers due to accumulation of clot or pericardial effusion). Inadequate decompression of the RV despite normal pump flow may occur if the distal tip of the device migrates into the RV outflow tract.

●Echocardiography during weaning and removal of RV support – (See 'Echocardiography during weaning and removal of RV support' above.)

•Echocardiography during weaning – Gradual weaning is accomplished by monitoring hemodynamic values and TEE or TTE indices of myocardial recovery.

•TEE during removal of cannulae – Removal of some percutaneously inserted temporary RV support devices and all centrally inserted cannulae is accomplished in the operating room when RV function has recovered or if the patient undergoes more definitive treatment (eg, heart transplantation, durable LV assist device [LVAD], palliative care). After removal, a complete TEE or TTE examination is performed to document the new "baseline" functions of the LV and RV and to assess whether iatrogenic tricuspid or pulmonic valve injury occurred during device insertion and use.

●Temporary biventricular support – (See 'Temporary biventricular support' above.)

•TEE to monitor support – TEE or TTE monitoring is critical for managing device flows to balance right and left circulations. Ideally, both atrial and ventricular septae are midline (indicating a balanced circulation) and decompression of both ventricles is adequate.

•TEE during removal of support – In some cases, intraoperative TEE or TTE is used to assess readiness to wean and explant both devices at lower levels of support. However, biventricular support is usually a bridge to decision for more definitive long-term therapy.