Chantal El Amm, MD and Leslie T. Cooper, Jr., MD

1. Why is an endomyocardial biopsy (EMB) performed?

    A few cardiovascular disorders can only or most accurately be diagnosed by examination of heart tissue. These disorders include giant cell myocarditis, amyloidosis, and allograft rejection. In each case, the unique information gained from EMB can inform prognosis and/or guide treatment. The information gained from EMB can also help diagnose certain restrictive cardiomyopathies and cardiac masses.

2. How is an EMB performed?

    A bioptome is shown in Figure 13-1. The Stanford-Caves-Schultz and the King bioptomes access the right ventricle through the right internal jugular vein. A modified Cordis bioptome (B-18110, Wolfgang Meiners Medizintechnik, Monheim, Germany) has been used for access from the right femoral vein. The subclavian and left femoral veins are used less frequently.

    The femoral artery may be used as a percutaneous access site for left ventricular biopsy.

    The right ventricular septum is the preferred site for EMB, to minimize the risk of perforation. Fluoroscopy and/or echocardiography guidance are essential to localize the site of biopsy. Endocardial voltage mapping has been used to identify biopsy sites in suspected arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) and cardiac sarcoidosis. Six to eight samples are generally obtained using the Stanford-Caves device. Up to ten samples are obtained by investigators who use the smaller Meiners Medizintechnik bioptome.

    The sample must be handled carefully to minimize crush artifacts. The biopsy specimen should be transferred from the bioptome to fixative by use of a sterile needle and not with forceps.

3. What are the risks associated with an EMB?

    Risks correlated with EMB are summarized in Table 13-1. EMB is associated with a serious acute complication rate of less than 1% using the current flexible bioptomes, and the overall rate of complication is reported as less than 6% in most case series. Complications include access-site hematoma, transient right bundle branch block (RBBB), transient arrhythmias, tricuspid regurgitation, and, rarely, pulmonary embolism. Life-threatening complications occur far less frequently. Right ventricular perforation was reported in less than 1% of patients. Following cardiac transplant, the risk is especially low. The risks of EMB depend on the clinical state of the patient, the experience of the operator, and site procedural volume.

4. How is the EMB tissue analyzed?

    Specimen preparation depends on the clinical question to be answered.

    Standard histological preparation for light microscopy can be used in the diagnosis of transplant rejection and myocarditis, and involves formalin fixation and paraffin wax embedding. Transmission electron microscopy requires glutaraldehyde fixation and can be helpful is the assessment of anthracycline drug toxicity and metabolic and storage disorders. Polymerase chain reaction for viral DNA amplification is best performed on unfixed samples. An RNase inhibitor is often used to prevent degradation of RNA virus genomes. Molecular typing of amyloidosis (e.g., AL, ATTR, and familial) is best performed with tandem mass spectroscopy.

5. When should EMB be performed?

    EMB is not commonly indicated in the evaluation of heart disease and should only be performed in specific clinical circumstances in which EMB results may meaningfully modify prognosis or guide treatment. In 2007, an American Heart Association, American College of Cardiology, and European Society of Cardiology (AHA/ACC/ESC) scientific statement recommended that EMB be used selectively in a limited set of clinical scenarios described in the answers to Questions 6 through 8. Since that statement, reports suggest that EMB may also have a role in the evaluation of idiopathic heart block for possible cardiac sarcoidosis or giant cell myocarditis.

6. What are the class I recommendations to perform an EMB?

7. When is it reasonable to perform an EMB (class IIa recommendation)?

8. When can you consider EMB (class IIb recommendation)?

9. What are some of the findings on pathology in different cardiac conditions?