TABLE 61.1 Common Indications for Endomyocardial Biopsy | ||||||||||||||||||||
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TABLE 61.2 Conditions Involving the Heart in Which Endomyocardial Biopsy Can Establish the Diagnosis, Listed According to the Presence or Absence of Proven Effective Therapy | |||||||||
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Endomyocardial Biopsy
Endomyocardial Biopsy
Mosi K. Bennett
Wilson W.H. Tang
I. INDICATIONS AND CONTRAINDICATIONS.
Endomyocardial biopsy (EMB) is less used now as a diagnostic tool for patients with systolic or diastolic dysfunction with the availability of more accurate noninvasive imaging techniques such as magnetic resonance imaging. Currently, the major indications for EMB are monitoring for allograft rejection after cardiac transplantation, as well as ruling out some potentially treatable forms of myocarditis. The role for this procedure in other disorders, such as arrhythmogenic right ventricular dysplasia, remains controversial because the diagnostic accuracy must be considered in relation to the lack of proven effective therapy. Potential indications and contraindications for EMB are listed in Tables 61.1, 61.2, and 61.3.
II. PATIENT PREPARATION.
As with any other procedure, extensive patient education and informed consent are necessary before starting the procedure. Patients undergoing EMB should be informed that there is a very small chance (<1% in experienced hands) of cardiac perforation, with potential urgent cardiovascular surgery and even death as a consequence.
Sedation is seldom needed but may help anxious patients better tolerate the procedure. Monitoring of heart rate by continuous electrocardiographic telemetry, blood pressure (noninvasively), and pulse oximetry is essential throughout the procedure. The patient should be monitored for a couple of hours after the procedure, as myocardial perforation with subsequent pericardial effusion may only become apparent some time after EMB. The patient is always positioned flat regardless of the venous approach. Venous access may be obtained through the internal jugular (most common), subclavian, or femoral veins. Ultrasound guidance or maneuvers to increase central venous pressure such as Valsalva, leg elevation with a wedge, and Trendelenburg position are helpful in obtaining venous access. Most centers use fluoroscopy as the imaging method of choice to guide EMB. However, echocardiography can also be used, particularly when radiation exposure needs to be minimized, such as in pregnant women.
III. DEVICES
A. Sheath.
Venous access is obtained using the Seldinger technique, and the sheath is always placed over a guidewire so as not to damage any vascular structures. A standard short sheath (11 cm, 7F or 8F) is generally sufficient for the right internal jugular or any subclavian approach. The intermediate-length sheath (24 or 35 cm) may be helpful to reduce venous angulation or to avoid damaging the vessel wall or a suture line when inserting the bioptome in patients with prior heart transplantation. For the left internal jugular approach, a longer sheath (40 cm, 7F) is used with a single- or double-curved tip based on operator preference and venous and cardiac anatomy. For a femoral approach, a curved 7F, 85-cm-long transseptal sheath is used, as it can be easily positioned into the right ventricle.
