Definition & Overview
Endomyocardial biopsy is the removal of a heart tissue sample to determine signs of damage or disease usually following heart transplantation. The procedure was introduced in the 1960s and has since evolved and refined to diagnose several heart conditions, especially cardiac allograft rejection. It involves the evaluation of the endocardium and myocardium. The former is the thin membrane lining the heart chambers while the latter is the heart muscles responsible for pumping blood.
Patients whose heart has been irreversibly damaged undergo heart transplantation where their diseased heart is replaced by a healthy donor heart. If the body considers the transplanted organ as a foreign body, its immune system will send antibodies to attack and effectively reject it. An endomyocardial biopsy helps cardiologists monitor how well the new organ fares inside the patient's body and gauge the success of the transplant procedure.
Tissue samples obtained through this procedure are evaluated using several techniques, such as immunohistochemistry and polymerase chain reaction, to complete the diagnostic process.
The actual method and technique used in performing biopsy vary from one condition to another and is dependent on several factors, including the patient's age and the severity of the condition.
Who Should Undergo and Expected Results
Endomyocardial biopsy is recommended for:
- Patients who underwent heart transplant surgery – These patients are routinely scheduled for an endomyocardial biopsy. Typically, they undergo the procedure every week during the first month following transplantation, every two weeks in the second and third months, and with increasing intervals in the following months.
- The diagnosis of cardiomyopathy or heart muscle disease, especially for those with unknown causes. This condition, which is characterized by enlarged, rigid, or scarred heart muscles, could progress to arrhythmias and even heart failure if left untreated.
- Patients on immunosuppressive therapy who are at risk of developing heart muscle conditions.
- Patients who experience inflammation of the heart muscles or myocarditis caused by viral infections, toxins, adverse reaction to medications, or as a result of an imbalanced immune system.
- Patients with unexplained arrhythmias
Other heart conditions that may be diagnosed using endomyocardial biopsy are cardiac sarcoidosis, cardiac tumors, and amyloidosis.
Although invasive, endomyocardial biopsy is considered a safe and effective diagnostic procedure with a very low rate of associated mortality and morbidity. Most studies report a complication rate of 1% or less, especially when performed by a highly skilled surgeon with long-term experience in this specific process.
How is the Procedure Performed?
Endomyocardial biopsy starts with the administration of local anesthesia. The insertion site is then cleaned and draped before the vein is punctured. In some cases, the surgeon uses sonography to locate and evaluate the right jugular vein before it is punctured and inserted with a guide wire and catheter. The surgeon then determines the exact path of the catheter to the heart with the use of imaging technology such as fluoroscopy or echocardiography. A tiny, pincher-shaped instrument called the bioptome is then inserted to collect several samples of heart muscles, which are then stored for histological evaluation. The catheter is then removed and the puncture site is closed.
An endomyocardial biopsy can be performed via the left or right subclavian vein if the right internal jugular vein is being used for a central venous line or when it is not advisable to puncture it due to possible thrombosis. Other possible access sites include the right and left femoral veins and arteries.
Possible Risks and Complications
An endomyocardial biopsy is linked to the following risks and complications:
- Ventricular perforation or tearing a part of the ventricular muscle, which could lead to internal bleeding
- Fluid buildup in the pericardial space, termed cardiac temporade, which may result in hemodynamic compromise or improper blood flow
- Temporary ventricular arrhythmias and the puncturing of central arteries Damage to the mitral or bicuspid valve, leading to regurgitation of blood. Heart transplant patients have a higher possibility of developing this complication as they undergo an endomyocardial biopsy on a regular basis.
- Pneumothorax or air embolism
Aside from hematoma, there are also minor complications that the patient and surgeons need to watch out for such as hypotension, vascular fistulae, nerve palsy, and chest pain.
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