Diagnostic tests for cardiovascular diseases

Wide Range of Options for a Highly Accurate Diagnostic

Many diseases fall within the category of heart disease, such as those related to arteries, the valve, or the myocardium and the weakness it may experience due to ischemia. Nowadays, cardiovascular diseases are the most deadly ones and the leading cause of death around the world, which has raised awareness about the possibility of prevention by avoiding some bad habits in daily life.

Statistics and huge numbers of patients with cardiovascular disease are the greatest motivation of many scientific studies and medical research that led to advanced treatments, which had a crucial role in making a radical change in medicine and heart disease. Some of the diseases that had been fatal in the past became treatable and with which the patient can live for several years. Modern treatments have been able to prolong the life of heart patients, provided they follow a healthy lifestyle.

Modern treatments have been preceded by a remarkable development in the diagnostic field. Cardiovascular diseases have had an ample share in terms of accurate diagnosis. Today, there is a wide range of diagnostic options that allow the doctor to check and look for heart palpitations, clogged arteries, cardiomyopathy, and other diseases that can affect the heart and its arteries.

Cardiology diagnostic tests contributed to a great extent not only to the development of an accurate treatment plan and prolongation of patients’ lives, but also to the early detection based on the principle of prevention, especially if the disease runs in the family. The patient can detect the disease before it occurs and reduce the possibility of its development by following advanced medical and therapeutic guidelines.

Electrocardiography (ECG)

This test detects the problems related to the electrical function of the heart by transforming the electrical activity in the heart from electrical signals to waves displayed on a paper.

Cardiologists consider this test a diagnostic tool if the patient suffers from arrhythmia, coronary artery disease that causes chest pain or a heart attack, a previous heart attack, or structural problems in the heart chambers. The mechanism of this test relies on activating each heartbeat by an electrical charge usually generated from special cells in the atrioventricular node, and then the ECG records the timing and strength of these signals as they travel through the heart.

The symptoms that require an ECG are:

• Heart palpitations.
• Chest pain.
• Shortness of breath.
• Dizziness.
• Weakness and inability to exercise.

This test provides the doctors with adequate information about the electrical function of the heart, which enables them to diagnose arrhythmia and determine the cause of chest pain, shortness of breath, heart palpitations, dizziness, and other symptoms.

It also ensures that there are no risk factors that may affect the heart function such as high blood pressure, high cholesterol, triglycerides, smoking, diabetes, and family history of heart disease. ECG can diagnose many heart diseases such as acute myocardial infarction, arrhythmia, hypertrophic cardiomyopathy, pericarditis, myocarditis, and abnormal sodium levels.

This test gathers information about electrical charges in the heart by connecting 12 leads to different areas of the body. These leads, or electrodes, are sensors for the body’s electricity that is related to the circulatory system, and are usually attached to the chest and upper and lower limbs. A standard ECG can record an abnormal heart rhythm only if it happens during the test. 

The patient lies on his/her back and small metal pieces (electrodes) are attached to his/her chest, wrists, and ankles after having sterilized the skin, and are connected to the ECG through electrical wires. After having attached the electrodes, the ECG is turned on to record the electrical signals in the heart and display them as waves on a special paper. The first thing to do is to inform the patient not to move or speak during this painless and risk-free test because this may distort the results.  It should be noted that some abnormal heart rhythms may be temporary; in other terms, they tend to come and go within a short period of time. In this case, the doctor may recommend another type of heart rhythm monitor, such as Holter monitor, a small device that can be worn for a day or two in order to record the heartbeats and monitor the heart.

Holter monitor

It is a battery-operated medical device that measures the heart’s activity, such as rate and rhythm. The doctor may recommend it to gather more detailed information about the heart functions because it is used for 24 hours during which it registers the heart rate. The Holter monitor also consists of electrodes, but fewer than the ECG. It is also known as the ambulatory electrocardiogram because the patient can wear it during the day and normally go about the daily life.

It is a small device that contains many leads connected to electrodes that are attached to the chest skin with a glue-like gel. These electrodes pick up the heart’s activity as electrical signals and then transmit them to the monitor. This test is performed if the patient has signs of a heart problem, such as irregular heartbeat or fainting for unknown reasons. It is preceded by an ECG, but it’s a short test and sometimes it doesn’t detect the problem. Therefore, the doctor resorts to the Holter monitor which helps to detect irregular heartbeat. The Holter monitor is also used to detect any pain in the chest and to look for other abnormalities that may affect the normal functioning of the heart. This test also helps to determine the long-term stability of the heart, whether the heart is getting enough oxygen, a delay of the electrical impulses in the heart, as well as the extent of the medication’s effect or whether any adjustments are needed. Once the monitoring period is over, the device will be returned to the doctor along with the registered data. Subsequently, he or she determines what is happening in the heart.

Echocardiogram

Echocardiogram, or cardiac ultrasound, is a procedure through which the structure and the function of the heart are assessed. The waves transmitted by a special device bounce off the heart structure, producing an image of it. The audio signal is converted by a computer attached to the echocardiogram to an image displayed on the screen. The doctor performs an echocardiogram to assess the size and function of the heart, to determine the cause of cardiomegaly, chest pain, or shortness of breath, to evaluate the function of the heart valves, to check the causes of fatigue, heart palpitations, or high blood pressure, and to determine the causes of blood clotting that may lead to a brain attack.

Echocardiogram helps the doctor diagnose certain diseases accurately and clearly in case the patient is suffering from a cardiac insufficiency, cardiomyopathy, irregular heartbeat, cardiomegaly, or heart clots.

Sometimes, it can be done annually to monitor the heart function in heart patients, to check the heart before an operation, to monitor it after an operation, or to assess the risk of heart disease that runs in the family.

Preparing for this test starts by injecting the patient with anesthesia. Then, he/she lies on the left side. The doctor or sonographer applies a gel to the chest near the heart, moves around a transducer, and starts recording images of the heart. This procedure takes between 30 and 60 minutes. This test doesn’t cause any pain but the patient may feel some discomfort in the chest or abdomen where the sonographer presses the device, which is necessary to obtain accurate images of the heart.

There are several types of echocardiograms:

• Transthoracic Echocardiogram (TTE): This traditional test is performed by placing the ultrasound device on the chest on top of the heart and thus conveying the image of the heart.
• Doppler Echocardiogram: It is a technical addition to the normal echocardiogram. It is possible to monitor the blood flow in the arteries, veins, and various parts of the heart. The only addition in this procedure is the use of the computer. This test assesses the blood flow in the heart valves, its velocity, and its pressure. The flow increases if the valve is tightened.
• Stress Echocardiogram: During this test, normal echocardiogram is performed before and after stressing the heart which can be done by physical exertion or by injecting the patient with medications that increase the speed of the heartbeat and the heart’s contraction. This test is used to diagnose coronary heart disease which leads to cardiac arrhythmia during effort due to a lack of blood flow to the heart.
• Transesophageal Echocardiogram (TEE): The tube containing the transducer is guided down the throat and into the esophagus so that the transducer is directed towards the heart. This type of echocardiogram records a clear image due to the proximity of the heart to the esophagus.

Radionuclide Ventriculography (MUGA SCAN)

It is an accurate method for assessing the general condition and situational status of the function of the left and right ventricles. Doctors resort to this technique in order to check the performance of the heart and the blood flow to it, and from it, in addition to examining the coronary arteries in charge of supplying the heart with blood. The narrowing of these arteries is called coronary artery disease. In short, it is possible to record images of the heart while pumping blood at each impulse.

This test provides a cine type of image of the heart while pumping blood, which means during its contraction and relaxation. It shows if there is an increase or a decrease of the internal size of the ventricle. Therefore, the doctor can measure the amount of blood during the different stages of the heart cycle and then calculate the equivalent of the blood pumping of the ventricle. This test is characterized by its accuracy and credibility compared to other tests.

Before the scanning, the patient is injected with a small amount of zinc pyrophosphate, which sticks to the red blood cells. After half an hour, the patient is also injected with radioactive technetium, which in turn follows the path of the pyrophosphate to stick to the red blood cells and make them radioactive. These substances allow the doctor to see and assess the inner wall of the ventricle.

A healthy heart muscle absorbs the radioactive substance. However, it is impossible if the patient suffers from a myocardial infarction because the muscle is transformed into a connective tissue that does not contract nor absorbs the radioactive substance.

During the scanning, the ECG starts recording because it is connected to the gamma device. The computer catches the heartbeat of the patient and generates a cine type of image of the contraction and relaxation of the ventricles, especially the left ventricle which is in charge of pumping blood to all parts of the body. The images obtained allow the doctor to assess the movements of the left ventricle and detect the cases of immobility, dyskinesia, or lack of movement. Any weakness of movement in any part of the ventricle wall indicates a narrowing of the coronary artery, whereas the lack of movement of the entire ventricle indicates a myocardial disease.

Few of the things that can be assessed while doing a MUGA scan are:

• Assessing the volume of the ventricular pumping of blood and its percentage.
• Estimating the function of the myocardium after a heart attack.
• Evaluating the results of the medical or surgical treatment of coronary atherosclerosis.
• Checking the effect of some medications on myocardial function.

The MUGA scan is performed after having injected a radioactive substance into the body through a vein, where the patient is lying down beside a camera that captures gamma rays emitted by the radioactive substance.

During an ECG, electrodes are attached to the patient’s chest. The radioactive substance is then injected and the patient should not move during the whole process.

Before conducting the MUGA scan, the patient should inform the doctor if he/she is taking certain medications or is allergic to a particular one. Women who are pregnant should not have a MUGA scan. 

In case a woman is breastfeeding, she has to stop it for two days after the test. The patient should abstain from eating for about three hours.