If needed, invasive tests may be performed to determine the severity of the cardiomyopathy and its effect on the heart. Cardiac catherization is one of the most useful and accurate tools for confirming the degree of cardiomyopathy. With certain forms of cardiomyopathy, such as arrhythmogenic right ventricular cardiomyopathy (ARVC), diagnosis can only be confirmed by cardiac catherization. If the cardiomyopathy appears to be secondary and there other associated medical problems, a muscle biopsy or genetic testing also may be recommended as part of the evaluation process.
Your child will be placed under local anesthesia during the following procedures:
During this procedure a thin flexible tube (catheter) is slowly guided through an artery or vein into the heart and is injected into the blood vessel so that special x-rays (angiograms) can be taken of the heart. Catheterization can be used for a range of diagnostic and therapeutic procedures, including checking for blockages in the arteries, measuring pressures in the heart chambers and assess the heart’s pumping ability. The information provided during the catheterization may be helpful if transplantation is being considered. Certain procedures that may be performed at the same time include an angiogram, endomyocardial (cardiac) biopsy or electrophysiology study. The basic procedure can take 2-3 hours.
This test helps to visualize the inside of blood vessels and chambers of the heart. Dye that is visible by X-ray is injected through a small tube (catheter) inserted into a blood vessel. The flow of the dye can be followed on a video monitor and recorded. The movement of the dye is tracked via images to measure blood pressures and flows inside the heart, as well as to determine heart function.
Electrophysiology (EP) Study
Similar to a heart catheterization, electrode catheters (flexible fine wires with metal electrode tips) are inserted through veins and threaded to the heart. Electrical stimuli are then applied to these wires to induce a very fast heart rhythm, which can be used to map the heart’s electrical system. The study tests for abnormal electrical conduction pathways, susceptibility to slow or fast arrhythmias, the effectiveness of anti-arrhythmic drugs, and the need for a pacemaker or implantable cardioverter defibrillator.
Also known as a cardiac muscle biopsy, the procedure entails use of a catheter to remove tiny pieces of heart muscle tissue for inspection under a microscope. This procedure is helpful in evaluating heart disease caused by infection, inflammatory processes, and metabolic or structural abnormalities of the heart muscle. With RCM cases it is used to distinguish cardiomyopathy from constrictive pericarditis and to search for potential causes of the condition such as amyloidosis, sarcoidosis. In ARVC cases it is used to verify whether there are fatty deposits within the heart’s right ventricular walls since an echocardiogram and angiogram may fail to identify any heart abnormality.
Skeletal Muscle Biopsy
This involves removing a tiny piece of muscle from an arm or leg to test for mitochondrial cardiomyopathy or a neuromuscular disease associated with cardiomyopathy, such as Duchenne muscular dystrophy. This procedure is recommended when not enough muscle tissue can be extracted from a cardiac biopsy.