We shall try to understand these through 11 questions and answers (since there are 11 players in a cricket team!)
Q1: What is an ECG ?
A1: ECG (ElectroCardioGram) is a basic, but extremely useful and important test in Cardiology. Like our mobile phones and laptops, the heart is a special organ that runs on electricity. Simply stated, the ECG is a picture of the electrical activity of the heart. Abnormalities in the structure, blood flow or rhythm of the heart can be understood from the ECG. However, it is important to understand that all heart diseases cannot be diagnosed by an ECG alone. A normal ECG therefore does not ‘guarantee’ a normal heart.
Q2: What does the heart look like on a Chest Xray ?
A2: The heart is situated comfortably inside the chest, between the two lungs. It has a slightly ‘leftist’ inclination. Even though it is a good thing to be ‘big hearted’ in our social interaction, an abnormal increase in the size of the heart (termed ‘cardiomegaly’) is one important clue to heart disease.
Q3: How does the Echo test help ?
A3: No, we are not talking about the Amazon Echo! In Cardiology, Echo is the short form of Echocardiography. Essentially, it’s an ultrasound scan of the heart, just as there are ultrasound scans of the abdomen or thyroid. What we get on an echo is something like a ‘live telecast’ of the heart in action (without commercial breaks!). We get information about the 4 chambers of the heart, the 4 valves, their function and so on. An important role of echo is in the measurement of the pumping capacity of the heart, described in terms of ‘Ejection Fraction’ (normally >60%).
Q4: What is the relevance of TMT ?
A4: TMT is the short form of ‘TreadMill Test. When a patient exercises by running on a Treadmill machine, the effect on the ECG is noted. If the coronary blood flow to the heart is normal, there will not be variation in the ECG pattern with exercise (‘TMT Negative’). On the other hand, in a patient
with significant ‘blocks’ in the coronary arteries (blood vessels that supply the heart), there will be ECG variations with exercise (‘TMT Positive’).
Q5: What is Troponin test ?
A5: Troponin is a protein that is present inside the cells of the heart in all normal human beings. When a patient develops a myocardial infarction (‘heart attack’),the cells get damaged and this protein is released into the bloodstream. Thus, the blood sample of a patient with heart attack will be ‘Troponin Positive’. Two important things to remember : Troponin test should be done in a timely fashion after a suspected heart attack (neither too early, nor too late). Conditions other than heart attack can also sometimes produce Troponin positivity.
Q6: How is a Holter test done ?
A6: The normal human heart is a pretty busy organ and beats regularly, 72 times in a minute. When the heart beats irregularly, or beats faster (tachycardia) or slower (bradycardia) than normal, these can produce symptoms. Holter monitoring is simply a means of recording the ECG in a person for a whole day to detect such abnormalities. For this, the patient wears a belt fitted with a recorder that is connected to the ECG Leads.
Q7: What is ABPM ?
A7: ABPM is Ambulatory BP Monitoring. It is a way of recording the variations in our blood pressure (BP) at various times of the day and night. For this, the patient goes about his usual routine for a day while wearing a BP cuff attached to the arm, while a recorder is worn at the waist.
Q8: Angiogram – Why ? How ?
A8: An angiogram is the ‘gold standard’ investigation to know about ‘blocks’ inside the coronary arteries. It is done by a Cardiologist in a specialised area called the Cath Lab. Tubes (catheters) are inserted through arteries in the hand or groin and advanced to the heart. Contrast agents are then injected through these tubes into the coronary arteries. This is visualised on computer screens as ‘blood flow’.
Q9: CT Coronary Angiogram – What is different ?
A9: Instead of taking catheters to the heart, contrast medication is injected into the patient’s vein and ‘blood flow’ is visualised on CT scans. Even though very useful in special situations, it is often less accurate than the ‘conventional’ angiogram.
Q10: Cardiac MRI - Utility ?
A10: The heart can also be scanned in an MRI machine (similar to brain scans and spine scans). This recent advance is of great value in certain specific diseases affecting the muscles of the heart. Ofcourse, care must be taken to ensure MRI compatibility of implants in patients undergoing this
Q11: So many tests ! Which one to choose?
A11: Each test has its own role. But remember, all these tests are not required for all heart patients. The first step is a proper history and examination by a Doctor, following which he/she will choose the appropriate investigations for that particular patient and context.
*Note : Tests and investigations should be done ONLY under the guidance of a qualified Doctor.