Cardiology: Non-Invasive
Heart disease is a catch-all phrase for a variety of conditions that affect the heart’s structure and function. The most common type of heart disease in the United States iscoronary artery disease(CAD), which affects the blood flow to the heart. Decreased blood flow can cause aheart attack.
Sometimes heart disease may be “silent” and not diagnosed until a person experiences signs or symptoms of a heart attack, heart failure, or an arrhythmia.When these events happen, symptoms may include:
- Heart attack: Chest pain or discomfort, upper back or neck pain, indigestion, heartburn, nausea or vomiting, extreme fatigue, upper body discomfort, dizziness, and shortness of breath.
- Arrhythmia: Fluttering feelings in the chest (palpitations).
- Heart failure: Shortness of breath, fatigue, or swelling of the feet, ankles, legs, abdomen, or neck veins.
High blood pressure, high blood cholesterol, and smoking are key risk factors for heart disease. About half of Americans (47%) have at least one of these three risk factors.2 Several other medical conditions and lifestyle choices can also put people at a higher risk for heart disease, including:
- Diabetes
- Overweight and obesity
- Unhealthy diet
- Physical inactivity
- Excessive alcohol use
An electrocardiogram is a non-invasive test used to determine or detect:
- Abnormal heart rhythm
- If blocked or narrowed arteries in your heart (coronary artery disease) are causing chest pain or a heart attack
- Whether you have had a previous heart attack
- How well certain devices, such as a pacemaker, are working
You may need an ECG if you have any of the following signs and symptoms:
- Chest pain
- Dizziness, lightheadedness or confusion
- Heart palpitations
- Rapid pulse
- Shortness of breath
- Weakness, fatigue or a decline in ability to exercise
An ECG may also be recommended due to a family history or other risk factors for heart disease even if you are not experiencing any symptoms. Alternatively, if your symptoms tend to come and go, they may not be captured during a standard ECG recording. In this case your doctor may recommend remote or continuous ECG monitoring such as a holter or event monitor.
An echocardiogram is a painless, non-invasive test that uses ultrasound (high-frequency sound waves) from a hand-held wand placed on your chest to view pictures of the heart’s valves and chambers to allow your doctor to evaluate the pumping action of the heart. When combined with Doppler ultrasound and color Doppler, an echocardiogram may be used to evaluate blood flow across the heart’s valves.
The test is used to:
- Assess the overall function of your heart
- Determine the presence of many types of heart disease, such as valve disease, myocardial disease, pericardial disease, infective endocarditis, cardiac masses and congenital heart disease
- Follow the progress of valve disease over time
- Evaluate the effectiveness of your medical or surgical treatments
Holter and event monitors can record how fast your heart is beating, whether the rhythm of your heartbeats is steady or irregular, and the strength and timing of the electrical impulses passing through each part of your heart. Information from these recordings helps doctors diagnose an arrhythmia, or irregular heartbeat, and check whether treatments for the irregular heartbeat are working.
Although similar, Holter and event monitors aren’t the same. A Holter monitor records your heart’s electrical activity the entire time you’re wearing it. An event monitor only records your heart’s electrical activity at certain times while you’re wearing it.
Most monitors have electrodes with sticky adhesive patches that attach to the skin on your chest. Some monitors and electrodes used for long-term recording may be implanted under your skin to make it easier for you to bathe and perform your daily activities. Your doctor will explain how to wear and use the monitor and tell you whether you need to adjust your activity during the testing period. You should avoid magnets, metal detectors, microwave ovens, electric blankets, electric toothbrushes, and electric razors while using your monitor. Usually, you will be instructed to keep electronic devices such as cell phones, MP3 players, and tablets away from the monitor. After you are finished using the monitor, you will return it to your doctor’s office or the place where you picked it up. If you were using an implantable recorder, your doctor will remove it from your chest.
An exercise stress test, also called a treadmill test or stress test, helps your cardiologist understand well your heart handles exertion. As your body works harder during the test, it requires more oxygen, so the heart must pump more blood. The test can show if the blood supply is reduced in the arteries that supply the heart.
The patient will be connected to monitoring equipment and walk slowly in place on a treadmill. Then the speed is increased for a faster pace and the treadmill is tilted to produce the effect of going up a small hill. Heart rate, breathing, blood pressure, electrocardiogram (ECG or EKG), and how tired you feel are monitored during the test.
Your cardiologist may recommend an exercise stress test to:
- Diagnose coronary artery disease
- Diagnose a possible heart-related cause of symptoms such as chest pain, shortness of breath or lightheadedness
- Determine a safe level of exercise
- Check the effectiveness of procedures done to improve coronary artery circulation in patients with coronary artery disease
- Predict risk of dangerous heart-related conditions such as a heart attack.
A nuclear stress test uses radioactive dye and an imaging machine to create pictures showing the blood flow to your heart. The test measures blood flow while you are at rest and are exerting yourself, showing areas with poor blood flow or damage in your heart. The test usually involves injecting radioactive dye, then taking two sets of images of your heart — one while you’re at rest and another after exertion. Such differences in the pictures helps your cardiologist determine whether there may be any major blockages in your arteries. They can also see if there has been damage to the heart muscle after a heart attack. The imaging additionally helps determine the best type of treatment you may need to correct any abnormal finding.
If your Cardiologist feels that you may not be able to tolerate an appropriate level of exercise on a treadmill, they may opt to use a pharmacological agent to mimic stress conditions to evaluate your heart. This may be used in cases of arthritis, poor conditioning, the use of certain blood pressure medications that prevent your heart rate from increasing with exercise, or the use of devices like a pacemaker of defibrillator.
Advanced lipid testing may be recommended by your healthcare provider to optimize your cholesterol treatment. Advanced lipid tests are performed because standard cholesterol tests may not completely represent cholesterol-related risk for heart attacks and strokes. Some people—especially people with diabetes, insulin resistance, or cardiovascular disease—continue to have progression of cardiovascular disease, even when their low-density lipoprotein (LDL) cholesterol is at goal.
Advanced lipid tests can be useful because some people do not have a lot of LDL cholesterol, but they have a lot of LDL particles. This can occur when they have mostly small particles or, alternatively, particles that contain less cholesterol per particle. A higher number of these lipoprotein particles make it easier for them to invade the walls of the arteries and induce a series of events that can lead to plaque formation. The LDL particle number measures the actual number of LDL particles that carry LDL cholesterol per liter of plasma. In addition to the number of LDL particles, advanced lipid tests report the size of these LDL particles, which may help your provider diagnose the cause of your cholesterol abnormality.
As with cholesterol goals, advanced lipid goals are reached through a combination of healthy lifestyle and cholesterol-lowering medication.
Like standard echocardiography, transesophageal echocardiography (TEE) uses high-frequency sound waves (ultrasound) to make detailed pictures of your heart and the arteries that lead to and from it. Unlike a standard echocardiogram, the echo transducer that produces the sound waves for TEE is attached to a thin tube that passes through your mouth, down your throat and into your esophagus. Because the esophagus is so close to the upper chambers of the heart, very clear images of those heart structures and valves can be obtained.
TEE can be used to determine:
- The size of your heart and how thick its walls are.
- How well your heart is pumping.
- If there is abnormal tissue around your heart valves that could indicate bacterial, viral or fungal infections, or cancer.
- If blood is leaking backward through your heart valves (regurgitation) or if your valves are narrowed or blocked (stenosis).
- If blood clots are in the chambers of your heart, in particular the upper chamber, for example after a stroke.