Heart tests are diagnostic tools used to evaluate the condition of the cardiovascular system. These procedures are often ordered when a patient reports symptoms such as chest pain, shortness of breath, or palpitations. They also help monitor existing heart conditions or assess risk factors like high cholesterol and high blood pressure. These examinations provide a detailed look at the heart’s function, structure, and ability to circulate blood effectively.
Tests That Map Electrical Activity
The heart operates based on a precise electrical conduction system that triggers muscle contractions. An Electrocardiogram (ECG or EKG) is the standard non-invasive test used to record these electrical signals. The procedure involves placing electrodes onto the skin of the chest, arms, and legs. These sensors detect the heart’s electrical impulses, which are translated into a wave pattern, allowing physicians to analyze the heart’s rate and rhythm. An EKG provides only a brief snapshot, which may miss intermittent rhythm problems.
Ambulatory monitors are portable devices worn by the patient over an extended period to catch these less frequent occurrences. A Holter monitor is worn for 24 to 48 hours and continuously records the heart’s electrical activity throughout the patient’s normal daily routine. Event recorders are utilized when symptoms are infrequent, sometimes occurring weeks apart. Unlike the Holter monitor, an event recorder is patient-activated; the patient presses a button to begin recording when symptoms are felt. This allows the device to capture the heart rhythm immediately before, during, and after the perceived event, which is valuable for diagnosing rare arrhythmias.
Imaging Tests for Structure and Pumping Power
Beyond the electrical system, heart tests may focus on visualizing the physical structure and mechanical strength of the heart muscle. The Echocardiogram (Echo) is a non-invasive technique that employs ultrasound technology to generate real-time moving images of the heart. This imaging allows for a clear view of the four chambers, the thickness of the heart walls, and the function of the heart valves. The Echo is valuable for measuring the heart’s pumping efficiency, quantified by the Ejection Fraction (EF). EF represents the percentage of blood the left ventricle pushes out with each contraction. A normal EF falls between 50 and 70 percent, and a reduced percentage may indicate heart failure.
Cardiac Computed Tomography (CT) uses X-rays to create detailed cross-sectional images of the heart and its major vessels. A common application is calcium scoring CT, which measures the amount of calcified plaque in the coronary arteries to estimate the risk of future cardiovascular events.
Cardiac Magnetic Resonance Imaging (MRI) uses strong magnetic fields and radio waves to produce highly detailed images without ionizing radiation. Cardiac MRI is employed to assess the characteristics of heart tissue, looking for signs of inflammation, scarring, or damage from a prior heart attack. These structural images provide information about the size of the heart chambers and the integrity of the muscle tissue.
Procedures That Measure Blood Flow and Performance
Testing the heart’s functional capacity, especially its ability to receive adequate blood flow under physical demand, is accomplished through performance-based procedures. Stress testing is designed to determine if the heart muscle receives sufficient oxygenated blood when it is working hard. This is achieved by raising the heart rate and blood pressure, either through physical exercise or medication.
The most common method is the exercise stress test, where the patient walks on a treadmill or pedals a stationary bicycle while their heart activity is monitored via an EKG. If a patient is unable to exercise, a pharmacological stress test can be performed, where a drug is administered intravenously to chemically simulate the effects of physical exertion. These tests reveal blockages in the coronary arteries that may not restrict blood flow at rest but become apparent when the heart’s demand for oxygen increases.
Stress tests are often combined with imaging, such as a stress echocardiogram or a nuclear stress test, to visualize blood flow directly. A nuclear stress test involves injecting a radioactive tracer, which allows a special camera to capture images of blood perfusion in the heart muscle at rest and during peak stress. Areas that do not properly absorb the tracer during stress indicate a potential narrowing or blockage in the supplying coronary artery.
For a definitive assessment of the coronary arteries, a procedure called Cardiac Catheterization, which includes coronary angiography, is employed. This is an invasive process where a thin, flexible tube, known as a catheter, is inserted into a blood vessel, typically in the wrist or groin. The catheter is then guided up to the heart and the openings of the coronary arteries.
A contrast dye is injected through the catheter, and X-ray images are taken, a process called angiography. The dye makes the blood vessels visible, highlighting any areas of significant narrowing or complete blockage caused by plaque buildup. Cardiac catheterization serves a dual purpose: it can be converted from a diagnostic procedure into an interventional one, such as angioplasty and stenting, to open up the blocked artery immediately.