Computerized tomographic angiography, also called CT angiography or CTA, is a test that combines the technology of a conventional CT scan with that of traditional angiography to create detailed images of the blood vessels in the body.
In a CT scan, x rays and computers create images that show cross-sections, or slices, of your body. Angiography involves the injection of contrast dye into a large blood vessel, usually in your leg, to help visualize the blood vessels and the blood flow within them. When the contrast dye is used to visualize your veins, the study is called a venogram, and when it is used to visualize your arteries, it is known as an arteriogram. CT angiography is similar to a CT scan, but the contrast dye is injected into one of your veins shortly before the x ray image is performed. Because the dye is injected into a vein rather than into an artery, as in traditional angiography, CT angiography could be considered less invasive.
Your physician may order CT angiography to help diagnose a narrowing or obstruction of the arteries, an aneurysm, deep vein thrombosis, pulmonary embolism, or another vascular condition.
During the study, you will lie down on a table, which passes through a donut-shaped device. Inside the device, a machine takes x rays in arcs around the area of your body being examined. Tissues of varying densities absorb these x rays in varying amounts. The computer assigns these densities different numerical values and then plots an image based on these values, in shades of gray. During the CT angiogram, a dose of contrast dye will be injected into one of your veins. As the dye flows through your circulatory system, it will highlight your blood vessels on the scan. A computer will produce 3-dimensional (3D) images of your blood vessels from the x ray images.
You may be unsuited for CT angiography if you:
- Have an allergy to contrast dye
- Have kidney problems
- Have severe diabetes
- Are pregnant, because radiation may harm the fetus
- Have unstable vital signs
- Weigh more than 300 pounds, because some x ray tables cannot support the weight
An echocardiogram (also called an echo) is a type of ultrasound test that uses high-pitched sound waves that are sent through a device called a transducer. The device picks up echoes of the sound waves as they bounce off the different parts of your heart. These echoes are turned into moving pictures of your heart that can be seen on a video screen.
The different types of echocardiograms are:
- Transthoracic echocardiogram (TTE). This is the most common type. Views of the heart are obtained by moving the transducer to different locations on your chest or abdominal wall.
- Stress echocardiogram. During this test, an echocardiogram is done both before and after your heart is stressed either by having you exercise or by injecting a medicine that makes your heart beat harder and faster. A stress echocardiogram is usually done to find out if you might have decreased blood flow to your heart (coronary artery disease).
- Doppler echocardiogram. This test is used to look at how blood flows through the heart chambers, heart valves, and blood vessels. The movement of the blood reflects sound waves to a transducer. The ultrasound computer then measures the direction and speed of the blood flowing through your heart and blood vessels. Doppler measurements may be displayed in black and white or in color.
- Transesophageal echocardiogram (TEE). For this test, the probe is passed down the esophagus instead of being moved over the outside of the chest wall. TEE shows clearer pictures of your heart, because the probe is located closer to the heart and because the lungs and bones of the chest wall do not block the sound waves produced by the probe. A sedative and an anesthetic applied to the throat are used to make you comfortable during this test.
It is common to find heart patients who have normal ECG. One must remember that the ECGs are taken at rest when the heart is beating at its lowest rate. Even with 90% blocks the patients can have a normal ECG. In such cases the patient would also agree that at rest there is no pain in the chest, the angina symptoms would only come when they increase the heart rate, while doing some physical exertion like walking.
This is the condition where we need a TMT test. The patients are to gradually increase their heart rate, thus increasing the blood requirement of the heart muscles. Simultaneously ECG records are taken. If there is a blockage of approximately more than 70% ECG shows changes, suggestive of Angina.
Patients have to physically exert for this test which uses a computerised machine. The level of the exercise is gradually increased according to a standard protocol called the Bruce's Protocol. The continuous ECG monitoring during the exercise would reflect any blood and oxygen deficit in the muscles of the heart during exercise. The patient is asked to stop exercising as soon as ECG changes appear or any symptoms of chest pain or discomfort or breathlessness are felt.
TMT test is also called Exercise Stress Test, Computerised Stress Test or simply Stress test. This is the most easy, popular and common test performed on heart patients to determine the severity of the heart disease. Taken at an interval, this test can also show the improvement or deterioration of patient's angina.
A negative TMT or Stress Test is declared when the patient can reach a certain heart rate without showing any ECG changes. This rate is called a target heart rate and is calculated by a formula (Target Heart Rate = 220 - age of patient). If this rate is reached by the patient without producing any ECG changes, though the TMT can be called negative, but it would not mean that the blockage is zero. It will only mean that the person performing the test probably has a blockage less than 70%
A stress echocardiography, also called an echocardiography stress test or stress echo, is a procedure that determines how well your heart and blood vessels are working.
During a stress echocardiography, you’ll exercise on a treadmill or stationary bike while your doctor monitors your blood pressure and heart rhythm. When your heart rate reaches peak levels, your doctor will take ultrasound images of your heart to determine whether your heart muscles are getting enough blood and oxygen while you exercise.
Your doctor may order a stress echocardiography test if you have chest pain that they think is due to coronary artery disease or a myocardial infarction, which is a heart attack. This test also determines how much exercise you can safely tolerate if you’re in cardiac rehabilitation. The test can also determine how well treatments such as bypass grafting, angioplasty, or anti-anginal or antiarrhythmic medications are working.
Dobutamine Stress Echo
An echocardiogram (echo) is a test used to assess the heart's function and structures. A stress echocardiogram is a test done to assess how well the heart works under stress. The “stress” can be triggered by either exercise on a treadmill or medication called dobutamine.
A dobutamine stress echocardiogram (DSE) may be used if you are unable to exercise. Dobutamine is put in a vein and causes the heart to beat faster. It mimics the effects of exercise on the heart.
During an echo, a transducer (like a microphone) sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed on the chest at certain locations and angles, the ultrasonic sound waves move through the skin and other body tissues to the heart tissues, where the waves bounce or "echo" off of the heart structures. The transducer picks up the reflected waves and sends them to a computer. The computer displays the echoes as images of the heart walls and valves.
A DSE may involve one or more of these special types of echocardiograms:
- M-mode echocardiogram. This, the simplest type of echocardiogram, produces an image that is similar to a tracing rather than an actual picture of heart structures. M-mode echo is useful for measuring heart structures, such as the heart's pumping chambers, the size of the heart itself, and the thickness of the heart walls.
- Doppler echocardiogram. This Doppler technique is used to measure and assess the flow of blood through the heart's chambers and valves. The amount of blood pumped out with each beat is a sign of how well the heart is working. Also, Doppler can detect abnormal blood flow within the heart, which can mean there is a problem with one or more of the heart's four valves or with the heart's walls.
- Color Doppler. Color Doppler is an enhanced form of a Doppler echocardiogram. With color Doppler, different colors are used to show the direction of blood flow.
- 2-D (two-dimensional) echocardiogram. This technique is used to see the actual structures and motion of the heart structures. A 2-D echo view looks cone-shaped on the monitor, and the real-time motion of the heart's structures can be seen. This allows the doctor to see the various heart structures at work and evaluate them.
- 3-D (three-dimensional) echocardiogram. 3-D echo technique captures 3-D views of the heart structures with greater depth than 2-D echo. The live or "real time" images allow for a more accurate assessment of heart function by using measurements taken while the heart is beating. 3-D echo shows enhanced views of the heart's anatomy and can be used to determine best treatment plan.
Electrodes (small conducting patches) are stuck onto your chest. These are attached by wires to a small recording monitor. You carry the Holter monitor in a pocket or pouch worn around your neck or waist. The monitor runs on batteries.
While you wear the monitor, it records your heart's electrical activity.
- Keep a diary of what activities you do while wearing the monitor, and how you feel.
- After 24 to 48 hours, you will return the monitor to your doctor's office.
- The doctor will look at the records and see if there have been any abnormal heart rhythms.
It is very important that you accurately record your symptoms and activities so the doctor can match them with your Holter monitor findings.
Electrodes must be firmly attached to the chest so the machine gets an accurate recording of the heart's activity.
While wearing the device, avoid:
- Electric blankets
- High-voltage areas
- Metal detectors
Continue your normal activities while wearing the monitor. You may be asked to exercise while being monitored if your symptoms have occurred in the past while you were exercising.