Non-Invasive Cardiology – Chevron Clinical Laboratory Pte. Ltd.

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Non-Invasive Cardiology


An echocardiogram is a type of ultrasound diagnostic test used by doctors to:

  • Assess the overall function of the heart
  • Determine the presence of any heart disease
  • Follow the progress of any heart valve disease
  • Evaluate the effectiveness of any medical or surgical treatment

An echocardiogram image is much more detailed than a plain x-ray, and involves no radiation exposure, thus making it much safer. Depending on what the doctor requires, a patient can expect to undergo several types of echocardiograms.

Common types of echocardiograms include:

  • Transesophageal echocardiogram
  • Stress echocardiogram
  • Transthoracic echocardiogram
  • Doppler echocardiogram
  • Dobutamine stress echocardiogram

In order to prepare for an echocardiogram, the doctor may ask patient to not eat for a few hours beforehand, especially if patient is about to conduct a transesophageal or stress echocardiogram. Patient need to wear comfortable shoes if undergoing a stress echocardiogram. Patient is advised to arrange for transportation as patient will not be able to drive after the test, due to the sedative medication patient will receive.

Tests: Several kinds of echocardiograms are offered, and the doctor will assess patient’s condition to determine which best suits patient’s needs. Patient may receive one, or more, of the following echocardiograms:

Transthoracic echocardiogram (TTE): The most standard of all echocardiograms, TTE makes use of the same technology used to evaluate a foetus’s health before birth. An ultrasound beam (sound waves) is passed through patient’s body by a handheld device known as a transducer, and a picture of patient’s heart is produced.

Transesophageal echocardiogram (TEE):This test requires a transducer to be guided down patient’s throat, and into patient’s esophagus, which links mouth and stomach. A TEE provides a much clearer and detailed picture of the heart structures as the esophagus is closer to the heart. During the procedure, patient’s throat will be numbed, and patient will be medicated to allow for maximum relaxation of the throat.

Stress or dobutamine stress echocardiogram: This is used to investigate the possibility of decreased blood flow to the heart muscles. Ultrasounds of the heart will be taken before or immediately after patient is asked to perform a series of exercises (either walking on a treadmill, or riding a stationary bicycle). Alternatively, the doctor may administer dobutamine, a drug that will cause the heart to simulate being put under stress, should patient be unable to conduct any physical movement.

Doppler echocardiogram: This procedure is used to examine blood flow in the heart chambers, valves and blood vessels. A transducer will bounce sound waves off the blood cells in the body, and the changes in pitch (also known as Doppler signals) can be calculated to measure the speed and direction of the blood flow.

Stress Test (ETT)

A stress test is a diagnostic test that collects and records information about how a patient’s heart responds to physical exertion. The test usually involves exercises such as walking on a treadmill, or pedaling a stationary bicycle at varying levels of difficulty. The patient’s heart rate and blood pressure are monitored to show if there is a lack of blood supply through the arteries that go to the heart.

Doctors can use the stress test to:

  • Determine if the blood flow to the brain is sufficient during times of exertion or increasing activity
  • Evaluate the effectiveness of heart medication to control anginas and ischemia
  • Determine the probability of coronary heart disease, and the need for further evaluation
  • Identify abnormal heart rhythms
  • Develop a suitable health programme or recommend the right kind and level of exercise

A stress test is also called exercise stress test, exercise electrocardiogram, treadmill test, graded exercise test, or stress ECG.

Test: The doctor may order a stress test as part of a health screening or when patient has symptoms, signs or risks that are suggestive of coronary artery diseases. A trained medical technician who will conduct the stress test will place 10 small pads on the chest to monitor the heart using an electrocardiogram (ECG), and measure the blood pressure.

During the stress test, patient will be asked to walk on a treadmill at a brisk pace for about 15 minutes and attempt to reach a certain heart rate (based on the age). Every three minutes, the treadmill will increase in speed and incline. The trained medical technician will supervise patient at all times and patient will not be forced to do more than a patient safely can.

Please allow about 45 minutes for the entire visit. To prepare for stress test:

  • Abstain from a heavy meal four hours prior to the test – patient may have a light meal of juice and toast
  • Wear comfortable walking shoes and a two-piece outfit as patient will be asked to undress from the waist up and given a hospital gown to wear
  • Do not smoke or have caffeine for three hours prior to the test
  • Patient is advised to bring a list of current medications
  • Patient should ask the doctor whether should take the regular medications prior to the test

Electrocardiography (ECG)

An electrocardiogram (ECG) is a diagnostic procedure that measures and probes for any complications or abnormalities with the electrical activity of the heart. An ECG translates the heart’s electrical activity into line tracings that doctors can use to detect abnormal heart rates and rhythms.

An electrocardiogram can be used to:

  • Check the heart’s electrical activity
  • Understand the cause of chest pains that may be the effect of heart attacks, inflammation of the heart sac, or anginas
  • Find the cause of symptoms of heart disease
  • Find out the thickness of the heart chambers
  • Assess the effectiveness of medication or the presence of side effects
  • Monitor the effectiveness of mechanical devices implanted in the heart
  • Examine the health of the heart when other diseases or conditions exist (such as high blood pressure, high cholesterol, diabetes or genetic heart disease)

An ECG is usually ordered to determine if a person is suffering from heart disease. The doctor may recommend an ECG if:

  • Patient has chest pains or palpitations
  • Surgery is scheduled
  • There is a strong family history of heart complications

 Test: An electrocardiogram (ECG) is conducted by a trained health professional, and the doctor will assess its results.

Before the test, the doctor will talk to patient regarding any medication patient is taking as the doctor may have instructions on how to take them prior to the examination. During the test, patient should not be wearing any jewelry or stockings; men will usually be bare-chested, while women may wear a bra, T-shirt, or gown.

During the procedure, several electrodes will be attached to the skin on each arm and leg, as well as the chest after the areas have been cleaned. The electrodes will then measure the heart’s electrical activity. Patient will be advised to lie still, and breathe normally, or perhaps asked to hold breath. As no actual electricity passes through the body during this procedure, an ECG is harmless and painless.

After the ECG, the doctor will discuss the results with patient. Abnormal results may have a variety of meanings, including:

  • Abnormal heart rhythms
  • Damage or changes to heart muscle
  • Changes of blood’s sodium and potassium leeks
  • Congenital heart defect
  • Enlargement of the heart
  • Fluid or swelling in the heart’s surrounding sac
  • Inflammation of the heart (myocarditis)
  • A past of current heart attack
  • Poor blood supply to arteries

Besides the standard ECG (sometimes called a resting ECG) described above, there are also other types of ECG:

  • Exercise ECG taken while patient is exercising to show how the heart copes under stress
  • 24- or 48- hour ECG where patient will be required to wear an electronic recorder for 24/48 hours (also called a Holter monitor or ambulatory ECG)
  • Cardiac event recorder that records patient’s heartbeat over a longer period of time

Blood Pressure : 24-hour ambulatory blood pressure monitoring (ABPM)

Ambulatory Blood Pressure Monitoring (ABPM) is when your blood pressure is being measured as you move around, living your normal daily life. It is normally carried over 24 hours. It uses a small digital blood pressure machine that is attached to a belt around your body and which is connected to a cuff around your upper arm. It small enough that you can go about your normal daily life and even sleep with it on.

Why might I need a 24-hour monitor?

By measuring your blood pressure at regular intervals over 24 hours, your doctor is able to get clear pictures of how your blood pressure changes throughout the day. There are a number of reasons why your doctor might suggest this test:

  • They may want to find out if your high blood pressure readings in the clinic are much higher than they are away from the clinic (called the “white coat effect”).
  • They may want to see how well your medicines are working, to make sure they are controlling your blood pressure through the day.
  • They may want to see if your blood pressure stays high at night. If this is the case, they may need to change or adjust your medicines.

What happens during 24-hour blood pressure monitoring?

Normally the machine is fitted at your local hospital outpatients department, although some GP surgeries may have their own.

A 24-hour blood pressure measurement is just the same as a normal blood pressure check: a digital machine takes your blood pressure by inflating a cuff around your upper arm and then slowly releasing the pressure. The machine is small enough to be worn on a belt on your waist while the cuff stays on your upper arm for the full 24 hours.

The machine then takes blood pressure readings at regular intervals throughout the day: usually, every 15-30 minutes during the daytime and 30-60 minutes at night. You will need to keep the monitor on through the night – you could put the machine under the pillow or on the bed while you sleep.

Because the test is being carried out to find out what your normal daily blood pressure is, it is important to carry on with your normal routine and do all the things you would normally do. The only things you should avoid doing for the day are swimming and having a bath or shower.

At the end of the 24 hours you can remove the machine and cuff and give it back to the hospital or surgery. The machine will have stored all your readings and these will then be analysed.

What do I need to do during 24-hour blood pressure monitoring?

To allow the machine to work properly, it is important to make sure that the tube to the machine is not twisted or bent. Also, just before the machine is about to take a reading, it will beep. When this happens you should:

  • sit down, if possible
  • keep the cuff at the same level as your heart
  • keep your arm steady.

You will also be asked to keep a diary of what you were doing just before the reading was taken, what time you went bed and got up and if and when you took medications. Some people find 24-hour ABPM distracting and uncomfortable: if you feel like this when the readings are being taken, speak your doctor or nurse as it may affect your reading.

24 Hour Holter Monitoring

A Holter monitor is a small, wearable device that records your heart rhythm. You usually wear a Holter monitor for 12 hours to 24 hours. During that time, the device will record the rhythm of your heart.

A Holter monitor test is usually performed after a traditional test to check your heart rhythm (electrocardiogram) isn’t able to give your doctor enough information about your heart’s condition, or you experience incidence symptoms infrequently or irregularly. Your doctor may also order a Holter monitor if you have a heart condition that increases your risk of an abnormal heart rhythm, such as hypertrophic cardiomyopathy. Your doctor may suggest you wear a Holter monitor for a day, even if you haven’t had any symptoms of an abnormal heartbeat.

While wearing a Holter monitor may be a little inconvenient, it’s an important test that may help your doctor diagnose your condition.

How to Prepare

You should bathe before this appointment because once your monitoring begins, you can’t get the monitor wet or remove the monitor to bathe.

Please make sure you wear loose fitting clothes on the day of your appointment and during the testing period. This is required because electrodes will be attached to your chest.

What to Expect

Holter monitoring is painless and noninvasive. Our technician will place some electrodes that sense your heartbeat on your chest. The electrodes are attached to your chest through tape-like adhesive and gel.  For men, a small amount of hair may be shaved to make sure the electrodes stick. The technician will then connect the electrodes to a recording device with several wires, and will instruct you on how to properly wear the recording device.

You can hide the electrodes and wires under your clothes, and you can wear the recording device on your belt or attached to a strap around your neck.

You’ll be asked to keep a diary and log of all the activities you do while wearing the monitor. In addition to all activities, you be asked to record in the diary the timing of any events – symptoms of palpitations, skipped heartbeats, shortness of breath, chest pain or lightheadedness. You’ll usually be given a form to help you record your activities and any symptoms.

In addition if symptoms are experienced while wearing the monitor there is a button on the monitor which can be pressed to inform the analyst of the time of the symptoms. Our technician fitting the monitor will show you this.

Once your monitor is fitted and you’ve received instructions on how to wear it, you leave our centre and resume your normal everyday activities.

Once your monitoring begins, don’t take the Holter monitor off — you must wear it at all times, even while you sleep.

While you wear a Holter monitor, you can carry out your usual daily activities. The length of time you are required to wear the Holter monitor will vary from 12 hours to 24 hours, depending on what condition your doctor suspects you have. Your doctor will advise you of how long the monitoring is to occur for.

After the Procedure

Once your monitoring period is over, you’ll need to come back to our patient center to return the Holter monitor

  • Our technician will then remove the electrodes from your chest, (similar to a bandage being pulled off your skin)
  • You hand to the technician the diary you kept while you wore the Holter monitor
  • You are then free to resume your normal everyday activities. Our cardiologists will review the holter monitor trace and will report the results.

These results are normally available to your doctor within 24 to 48 hours.