Introduction
Intracardiac masses (ICMs) are rare entities in clinical practice. The differential diagnosis is wide, including pathologies such as infective, thrombotic, neoplastic, autoimmune, iatrogenic, or hamartomatous lesions. Unless clearly associated with a specific clinical scenario, such as valvar vegetations in infective endocarditis or appendage thrombus in atrial fibrillation, they can present a significant diagnostic challenge. Although imaging modalities like transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET) can be used to suggest a diagnosis, they may not be conclusive. A histopathologic diagnosis may significantly change clinical decision-making and treatment options. This is especially true for cancer therapies, which may require molecular targeting and cause systemic toxicity.
The heart presents significant barriers to retrieving tissue for diagnosis. It sits deep in the mediastinum surrounded by vital organs and is in constant motion with every heartbeat. This makes CT- or MRI-guided needle biopsy approaches difficult or impossible. Cardiac surgeons can biopsy these masses, but the patient must undergo general anesthesia, cardiopulmonary bypass, median sternotomy, cardiac reconstruction, wound healing, and general rehabilitation, all of which come with a risk of morbidity and mortality. For intracardiac lesions that do not cause compressive symptoms necessitating immediate excision, transcatheter biopsy (TCB) can offer a minimally invasive route to a histopathologic diagnosis.
AHA guidelines
| Fulminant heart failure <2 weeks duration | I | B |
| Heart failure of 2 weeks to 3 months duration with dilated left ventricle (LV) with ventricular arrhythmias or atrioventricular (AV) block or refractory to conventional therapy | I | B |
| Dilated LV with ventricular arrhythmias or AV block or refractory to conventional therapy of >3 months duration | IIa | C |
| Selected cardiac masses | IIa | C |
| Dilated LV with eosinophilia | IIa | C |
| Restrictive cardiomyopathy or suspected anthracycline toxicity, not diagnosed by imaging | IIa | C |
| Cardiac transplantation surveillance | Not covered by guidelines |
Selection
The patient who undergoes TCB for ICM should meet several criteria as described in the following sections.
Clinical considerations
First, there must be concrete clinical benefit in performing biopsy of an ICM to establish histopathologic diagnosis. The mass must remain undiagnosed despite noninvasive study. Simple entities like endocarditic vegetations and appendage thrombus can be diagnosed with reasonable certainty and treated with standard therapies after echocardiographic diagnosis—such lesions should not be biopsied unless the clinical picture is unclear. The specific benefit of histopathologic diagnosis is either an increased accuracy of molecular targeting, such as ligand-specific chemotherapy for cancer metastases, or the obviation of cardiac surgery for compressive lesions that can be resolved without excision, such as primary cardiac lymphoma. There is also a role for establishing a histopathologic diagnosis to guide an informed transition to palliative care for patients with incurable pathology.
Technical considerations
Second, there must be a focal ICM in the heart accessible by the intravascular route or through the anterior chest wall. The lesion should be continuously visible by echocardiography, either TTE or TEE, which is critical for procedural guidance. Lesion size must be sufficient to allow engagement by the biopsy equipment, but there is no concrete size at which biopsy must be abandoned, and lesion morphology will also affect the likely success of a biopsy. Masses that are sessile and circumscribed are more likely to be engaged with biopsy equipment compared with lesions that are pedunculated and filamentous. Masses that are highly mobile are more difficult to biopsy. The location of the lesion in the cardiovascular system should be considered. As with any structural procedure, relational anatomy will dictate expected complications. Lesion proximity to structures such as the sinoatrial node, AV node, His bundle, and prosthetic or native valve leaflets should raise concern. Right-sided masses are more accessible and carry a lower risk of systemic thromboembolism compared with left-sided masses. Mass lesions located on the interatrial and interventricular septum present a lower risk of cardiac perforation and pericardial tamponade compared with free wall lesions.
Planning
Planning considerations should include vascular access selection, mass visualization, mass navigation, bioptome delivery, and access site closure. Reconstruction of CT or MRI in 3D allows for a better understanding of mass size, mass characteristics, surrounding relations, access route length, and working angulations, and the potential for complications and available imaging should be thoroughly studied before biopsy. Because all access considerations are dependent on the size of the biopsy device to be used, we will start with a discussion of biopsy equipment.
Biopsy equipment
Medical tools to remotely retrieve cardiac tissue include the standard endomyocardial bioptome (Jaws, Argon Medical, Frisco TX), hepatic side-cutting needles (BX Needle, Cook Medical, Bloomington, IN), and gastrointestinal biopsy forceps (EndoJaw, Olympus Medical, Tokyo, JP) ( Fig. 31.1 ). All devices are compatible with an 8F hemostatic sheath. A complex avulsion approach with a combination of a loop snare to electrosurgically sever the base of a mass (Gooseneck, Medtronic, Minneapolis, MN) and a trileaflet snare (EN Snare, Merit Medical, South Jordan, UT) to retrieve the mass can be considered in sites where embolic potential is limited. The sheath size should be large enough to accommodate the size of the mass in order to extract it. We have performed a single biopsy of an anterior cardiac mass via the percutaneous transthoracic approach using a Jamshidi bone marrow biopsy needle (Beckton Dickinson, Franklin Lakes, NJ), but this is a high-risk procedure and may not be replicable at other centers.
Biopsy equipment selection should be tailored to the lesion. For masses that are thought to be relatively soft based on imaging characteristics, the endomyocardial bioptome allows for targeted lesion sampling without damage to surrounding structures. In cases where the mass is thought to be relatively hard, contained in a fibrous pellicle, covered with chronic thrombus, and has enough noncritical surrounding tissue to allow for biopsy-targeting errors, a side-cutting needle or EndoJaw biopsy forceps can be considered.
The Quick-Core side-cutting needles are designed for transjugular hepatic and renal biopsies in coagulopathic patients. The needle throw is 2 cm, and one should make sure that there is enough mass length to accommodate the full length of the needle without penetration into other structures behind it. Operators should note that sheath length may be a limiting factor when these needles are used. The transjugular hepatic biopsy needle has a total length of 50 cm. It has a sharp tip that will not traverse standard hemostatic sheaths. A 7F metal introducer tube is included and must be used to avoid piercing sheaths with the needle while inserting it into the body. The transjugular renal biopsy needle has a length of 70 cm. The added length may be advantageous for antegrade transseptal or retrograde aortic procedures. Although it is also supplied with a 7F metal introducer, it has a blunt tip that can be directly introduced into hemostatic sheaths without risk of traversing the sheath wall. The main reason to use a liver biopsy needle, other than anatomic accessibility, is that ICMs, particularly tumors, are often encapsulated, and the standard jaws of our bioptomes will not penetrate this type of lesion.
The EndoJaw biopsy forceps are designed for remote biopsy of gastrointestinal lesions through endoscope lumens. The standard version has a 2-mm diameter and requires an 8F sheath. It has three traumatic teeth on either side and may avulse a large portion of the mass because of the force with which tissue can be gripped. Masses located close to valves should be avoided with this approach. Serial use of a variety of biopsy devices may allow sampling at different mass depths. It is unknown if this increases diagnostic yield.
Access sizing
Sheath size is dependent on the biopsy equipment chosen. We recommend the use of a long, braided straight or curved sheath to avoid having to steer through the femoral venous vasculature with the biopsy instrument. Embedding the sheath into the mass allows rapid repeat sampling with the biopsy instrument without have to navigate each time. A steerable sheath (Agilis NXT, Abbott Vascular, St. Paul, MN) can be useful in tortuous anatomies or angulated mass locations. A combination telescoping technique using a standard vascular sheath and a large-bore coronary guiding catheter might be an alternative if a steerable sheath is not readily available. Care should be taken to ensure that the selected biopsy equipment will fit through the selected sheath before starting the procedure. Suture-mediated closure devices (Perclose Proglide, Abbott Vascular, St. Paul, MN) can be considered for hemostatic closure when large-bore sheaths are used. In cases where intracardiac echocardiogram (ICE) is required for mass visualization and biopsy guidance, a separate vascular access sheath should be inserted.
Mass visualization
Echocardiographic guidance is crucial for accurate mass biopsy and avoidance of complications. Either TTE or TEE should be used in all cases. Visualization of atrial masses may be limited with 3D TTE, which is better suited for ventricular mass biopsy. TEE with 3D is the modality of choice for atrial mass biopsy, and can also be used to guide transseptal puncture. TEE for the duration of the biopsy will typically require general anesthesia, and preprocedure consultation with cardiac anesthetists should be obtained. The presence of a trained structural imaging cardiologist to guide the procedure can be invaluable. ICE alone can be used for biopsy of large atrial masses, but a 3D understanding of ICM location and its relationship to the tip of the bioptome is necessary for effective imaging and may be challenging. Supplemental imaging with TTE or TEE during the case is recommended in this situation.
Bioptome delivery
Right-sided masses
For masses located in the vena cavae, right atrium, and right ventricle, access is relatively straightforward. The internal jugular vein (IJ) or femoral vein (FV) are recommended access sites. The IJ route allows for natural steering into the right ventricle or pulmonary artery, akin to a Swan-Ganz catheter. It allows for better bioptome control given the smoother approach and shorter distances, especially when accessing masses located in the right ventricle or pulmonary artery. The ergonomics of catheter management from the IJ are challenging compared with the FV approach. Right-sided masses are well visualized with TTE, unless they are located in the interatrial septum, in which case TEE is recommended. Care should be taken to avoid the tricuspid valve leaflets and subvalvular chordae when performing the biopsy. We recommend using standard-dose anticoagulation for these procedures (iStat ACT 200-300s).
Left-sided masses
Potential access routes include antegrade transseptal (TS) and retrograde aortic (RA). The TS approach is well suited to a mass located in the left atrium and basal-to-mid ventricle. In these locations, care should be taken to avoid the pulmonary vein ostia and mitral valve chordae during bioptome operation. The RA approach is better for apical left ventricular masses. We do not recommend its use for other ventricular locations given interference with mitral chordae and difficulties with steering once inside the ventricle. Potential complications include in situ thrombus formation and systemic embolization. Carotid filters such as a multivessel protection device (Sentinel, Claret Medical, Santa Rosa, CA) or multiple basket filters (Spider FX, Medtronic, Minneapolis, MN) can be considered. These may not be uniformly protective. The specific risk of embolization remains unknown. We recommend an in-depth discussion about the risks and benefits of left-sided mass biopsy with the patient before the procedure. We also recommend performing such biopsies in locations where neurointerventional assistance for cerebral embolectomy is readily available if required. We recommend high-dose anticoagulation in this setting (iStat ACT 300-400s), recognizing that the risk of pericardial effusion is increased.
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