A cardiologist checks your heart through a combination of physical examination, electrical recordings, imaging, blood tests, and sometimes invasive procedures. Most visits start with simple, noninvasive steps and only move to more advanced testing if those initial results raise questions. Here’s what each method involves and what it reveals.
The Physical Exam
Before any technology enters the picture, a cardiologist listens to your heart with a stethoscope. This isn’t a formality. The sounds your heart makes tell a trained ear a surprising amount about how your valves and chambers are functioning.
A healthy heart produces two main sounds with each beat. Beyond those, a cardiologist is listening for three categories of abnormal sounds. Murmurs are caused by turbulent blood flow and sound like a whooshing or swishing noise. They can occur between beats or during them, and the timing tells the cardiologist which valve is involved. A murmur heard while the heart is squeezing, for instance, could point to a narrowed aortic valve or a leaking mitral valve. Gallops are extra sounds during the filling phase of the heartbeat, often a sign that the heart is under strain or not pumping efficiently. Clicks are brief, high-pitched sounds that can indicate a valve is prolapsing, meaning it’s bowing backward slightly when it closes. A cardiologist may ask you to stand, lie down, or bear down (a technique called the Valsalva maneuver) because these position changes shift the timing of clicks and help pinpoint the problem.
The cardiologist also checks your blood pressure in both arms, feels your pulse at several points, looks for swelling in your legs, and examines the veins in your neck for signs of elevated pressure in the heart.
Electrocardiogram (ECG or EKG)
An ECG is usually the first test ordered. It takes about 10 minutes, involves no needles or radiation, and records the electrical activity of your heart through small adhesive patches placed on your chest, arms, and legs.
The resulting tracing has distinct waves that each represent a specific event. The P-wave shows the upper chambers firing. The QRS complex, a sharp spike that normally lasts about 0.08 seconds, shows the lower chambers contracting. The segment that follows reflects the heart resetting its electrical charge before the next beat. Abnormalities in the shape, timing, or size of these waves can reveal irregular rhythms, signs of a previous heart attack, thickened heart muscle, or electrical conduction problems. An ECG is a snapshot of one moment, though, so if your symptoms come and go, you may need longer monitoring.
Holter and Event Monitors
When symptoms like palpitations, dizziness, or fainting happen unpredictably, a standard ECG might look completely normal. That’s where portable monitors come in. A Holter monitor is a small device you wear continuously for 24 to 48 hours while going about your normal routine, even sleeping. It records every heartbeat during that window.
If your symptoms are less frequent, an event monitor may be more useful. You wear it for several weeks, up to 30 days, and it either records continuously or captures data when you press a button during a symptom. Some newer patch-style monitors stick directly to your chest and require no wires at all. The goal with both devices is to catch an abnormal rhythm in the act, linking what you feel to what your heart is actually doing electrically at that moment.
Stress Testing
A stress test shows how your heart performs under physical demand. The most common version uses the Bruce protocol: you walk on a treadmill that gets faster and steeper every three minutes across up to seven stages. If you make it to the final stage, you’re walking at 5.5 miles per hour on a 20% incline. Most people don’t reach that point, and they don’t need to. The cardiologist monitors your ECG, blood pressure, and symptoms throughout, looking for changes that suggest reduced blood flow to the heart muscle.
If you can’t exercise due to joint problems or other limitations, a medication can be given through an IV to simulate the effect of exercise on your heart. Stress tests are sometimes combined with imaging (either ultrasound or a nuclear tracer) to create pictures of blood flow to different parts of the heart during peak exertion and at rest. Areas that don’t light up properly during stress may have blocked or narrowed arteries supplying them.
Echocardiogram
An echocardiogram is an ultrasound of the heart. It uses sound waves to produce a live, moving image of the chambers, valves, and surrounding structures. It’s painless, takes 30 to 60 minutes, and involves no radiation. A technician presses a handheld probe against your chest while you lie on your side.
One of the most important numbers from an echocardiogram is the ejection fraction, which measures what percentage of blood the left ventricle pumps out with each beat. A normal ejection fraction falls between 55% and 70%. A reading from 41% to 49% is considered mildly reduced. Below 40% typically indicates heart failure or cardiomyopathy. Interestingly, a reading above 75% can also be a problem, potentially signaling a condition where the heart muscle is abnormally thick. Beyond ejection fraction, the echocardiogram shows valve function in real time: whether valves open fully, close tightly, or leak.
Coronary Calcium Scan
A coronary calcium scan is a specialized CT scan that measures the amount of calcium buildup in the walls of your coronary arteries. Calcium deposits are a marker of plaque, which is the fatty material that narrows arteries over time. The scan takes only a few minutes, requires no contrast dye, and produces a number called a calcium score.
A score of zero means no calcium was detected, suggesting a low risk of heart attack in the near future. A score between 100 and 300 indicates moderate plaque and a relatively high risk of heart attack or other heart disease over the next three to five years. A score above 300 signals more extensive disease and higher risk. This test is most useful for people at intermediate risk, where the result might tip a treatment decision one way or another. It’s less helpful if your risk is already clearly low or clearly high based on other factors.
Blood Tests
Blood work gives the cardiologist a chemical picture of your heart health. Standard panels include cholesterol levels, blood sugar, kidney function, and markers of inflammation. But the most heart-specific blood test measures troponin, a protein released when heart muscle cells are damaged.
Modern high-sensitivity troponin tests can detect extremely small amounts of this protein. Each lab uses a specific cutoff, but in general, a level above the 99th percentile for the test being used signals heart muscle injury. These thresholds differ between men and women. For one widely used test, the cutoff is 17 ng/L for women and 35 ng/L for men. Rising troponin levels over a series of blood draws, rather than a single reading, is what most clearly points to an active heart attack versus chronic low-level damage from other causes.
Cardiac MRI
When a cardiologist needs the most detailed view of the heart’s structure and tissue, a cardiac MRI is the gold standard. It produces high-resolution images without radiation and can distinguish between healthy muscle, scar tissue, inflammation, and fat infiltration.
One particularly powerful technique involves injecting a contrast agent and then imaging the heart about 10 to 15 minutes later. Damaged or scarred tissue holds onto the contrast longer than healthy tissue, creating bright areas on the scan. The pattern of those bright areas tells the cardiologist what caused the damage. Scarring that starts on the inner wall and follows the territory of a coronary artery points to a previous heart attack. A patchy pattern on the outer wall, especially along the base of the heart, is a hallmark of myocarditis (inflammation of the heart muscle). Scarring in the middle of the wall suggests cardiomyopathy. These distinctions matter because each condition requires a different treatment approach, and cardiac MRI can make them without surgery or biopsy.
Coronary Angiogram
If noninvasive tests suggest a blockage, the cardiologist may recommend a coronary angiogram, the most direct way to see inside the arteries. This is a catheter-based procedure done in a hospital, typically under local anesthesia with mild sedation.
The cardiologist makes a small incision, usually at the wrist (radial artery) or sometimes at the groin (femoral artery), and threads a thin, flexible catheter through the blood vessel up to the heart. Contrast dye is injected through the catheter, and X-ray images are taken in real time. The dye fills the coronary arteries, making them visible on screen. A narrowed or blocked section shows up as a point where dye flow slows or stops. If a significant blockage is found during the procedure, the cardiologist can often treat it on the spot by inflating a small balloon and placing a stent to hold the artery open.
Recovery from the procedure itself is relatively quick. Most people go home the same day if the catheter was placed at the wrist, or the next day if the groin was used. You’ll be asked to keep the access site still for several hours to prevent bleeding, and most people return to normal activities within a few days.
How Cardiologists Decide Which Tests You Need
Not every patient gets every test. The cardiologist starts with your symptoms, medical history, family history, and physical exam, then works outward. Someone with occasional palpitations and no other risk factors might only need an ECG and a Holter monitor. A person with chest pain and diabetes might go straight to a stress test with imaging. The sequence is designed to get the clearest answer with the least invasive approach first, escalating only when simpler tests leave unanswered questions.