Diagnosis of Heart Murmur
Typically, heart murmurs are discovered when a physician listens to the heart with a stethoscope during a routine physical examination. If the physician detects any unusual heart sounds, he or she will ask about the patient's medical and family history and about the presence of any symptoms (e.g., chest pain, shortness of breath).
Physicians consider several points when evaluating a heart murmur:
- Volume (rated on a scale of 1 [softest] to 6 [loudest])
- Pitch (murmurs may be high-, medium-, or low-pitched)
- Location (murmurs also may be heard in the neck, back, or another part of the chest)
- Timing (murmurs may occur throughout the heartbeat cycle [continuous] or just during the resting stage [diastole] or contracting stage [systole]; physicians also may note whether the murmur is heard early or late in the corresponding stage or cycle)
- Changes in the sound of the murmur (e.g., when the patient stands, sits, squats, grips an object, holds his or her breath, or exercises) can give the doctor clues about the murmur
If an abnormal heart murmur is suspected, additional diagnostic tests may be performed. A chest x-ray can be used to detect an enlarged heart and congenital defects.
Blood tests can reveal signs of infection, such as endocarditis. An electrocardiogram (ECG or EKG), which records electrical impulses, can provide information about heartbeat, rhythm, and abnormalities.
Echocardiography uses sound waves to produce images of the heart. Physicians can use cardiac echo to analyze the heart's structure, shape, size, contractions, and the function of chambers and valves.
Several types of echocardiography are available. Doppler echocardiography produces images that show blood flow patterns. Stress echocardiography shows whether blood flow decreases following exercise or after taking medicine that makes the heart beat faster.
Transthoracic echocardiography can detect calcified or leaking heart valves and most congenital heart defects. If the images from transthoracic echocardiograms are not clear, the physician may order a transesophageal ultrasound. In this test, the patient swallows a device that records the sound waves to produce the images. The esophagus (tube that carries food and liquids from the mouth to the stomach) is close to the heart and transesophageal ultrasound may produce clearer images than traditional echocardiography.
In cardiac catheterization, a thin tube is inserted into a blood vessel (usually in the groin, arm, or neck), a catheter is threaded through the tube into the blood vessel and to the heart, and a contrast agent (special dye) is injected. X-ray images are used to guide the catheter and to measure oxygen levels in the chambers of the heart and detect blood flow patterns and structural abnormalities.
Computerized tomography (CT scan) and magnetic resonance imaging (MRI scan) also may be used to diagnose heart murmurs.