Because of enormous development in laboratory tests and imaging techniques, the value of cardiological examination is often underestimated. Not only patients, but sometimes doctors also try to find a disease based on laboratory tests and imaging results.
But this may sometimes lead to unnecessary tests, loss of time and money, and diagnosing an incidental finding as a disease, which has nothing to do with the symptoms and treating it doesn’t have any effect on the life of the patient.
That is why a detailed cardiological examination is an indispensable step to diagnose a disease and plan a therapy. We gather detailed information about the symptoms, past medical history, family history, drugs being used in the past and present, lifestyle, diet, and habits (smoking, drinking alcohol, illicit drugs), occupation, hobbies, etc. Then we proceed to a detailed systemic and cardiovascular physical examination, including major blood vessels like carotid arteries, upper and lower extremity arteries, renal arteries, abdominal aorta, etc.
After gathering information about the complaints, detailed history, and physical examination, we come to a differential diagnosis. To support the most probable diagnosis and to exclude the rest, we have to do certain tests. Usually, the tests are chosen according to the pretest probability of the patient to certain cardiac diseases and patient characteristics.
What are the main tests used in cardiology?
As cardiologists, we can order a series of tests, but some are more specific for the diagnosis and treatment of cardiovascular diseases.
Electrocardiogram (ECG)
ECG records the electrical activity of the heart from electrodes (10 electrodes – 4 extremities and 6 chest) attached to the patient’s body. ECG provides information about heart rate, basal heart rhythm, heart axis, helps diagnose heart attacks before blood test results, diagnose arrhythmias, and gives information about other cardiovascular diseases like hypertension, past heart attacks, coronary artery disease, valvular stenosis and insufficiency, pulmonary hypertension, pulmonary embolism, and ST-segment elevation heart attack. It also protects us from conducting unnecessary tests and saves time and money. In ST-segment elevation heart attack, it helps diagnose within 10 minutes of the patient entering the emergency department, allowing for immediate transfer to the cath lab, which can save lives.
Blood Tests
Blood tests help diagnose heart attack, hyperlipidemia, thyroid hormone disorders, fatty liver, and microalbuminuria in patients with hypertension and diabetes. They also identify certain risk markers of coronary artery diseases like homocysteine and high-sensitive CRP. Blood tests play an essential role in the follow-up of patients with acute heart failure and patients under high-dose diuretics.
Rhythm Holter
A normal ECG can miss arrhythmias that are not persistent but intermittent. Patients with suspected intermittent arrhythmias can be monitored with a 24, 48, or 72-hour rhythm monitoring device called a Rhythm Holter. The data obtained during these hours are stored and transferred to a computer, which is then read by a cardiologist. Neurologists also frequently use Rhythm Holter to detect paroxysmal atrial fibrillation in patients with stroke.
Tension Holter
Some patients have high blood pressure at the hospital and normal at home. Some patients may have only incidental high blood pressure, while others may have nocturnal high blood pressure and sleep apnea. Tension Holter helps diagnose real hypertension, exclude pseudohypertension, and sometimes diagnose the type and cause of hypertension (e.g., white coat hypertension, stress-induced hypertension, sleep apnea-induced hypertension).
Echocardiography (ECHO)
ECHO helps determine cardiac function (contractile power, ejection fraction), diagnose valvular heart disease, congenital heart disease, shunts (intracardiac and between major vessels), anatomy and dimension of major vessels (aorta and pulmonary artery), aortic dissection flap, pulmonary embolism (right heart dilation), pulmonary hypertension and its causes, previous heart attack, coronary artery disease (segmental wall motion abnormality), and complications after heart attack (valvular insufficiencies, chordae rupture, pericardial effusion, etc.).
Treadmill Exercise Test
From the history and physical examination, we classify a patient in a risk group for coronary artery disease. The exercise test has a specificity and sensitivity of 70-80%. That’s why this test is suitable for patients who are at intermediate risk for coronary artery disease. Exercise stress is used not only to determine the presence of coronary artery disease and its extent but also the functional capacity of the patient in various conditions like preoperative risk assessment, aortic stenosis assessment, and functional class assessment after a myocardial infarction. Patients run on a treadmill with speed and inclination increasing every three minutes. We increase the oxygen demand of the heart muscle and check whether the coronary artery supply is enough. When there is a supply-demand mismatch, subendocardial ischemia occurs, which is presented either by chest pain or ST segment depression in an ECG.
Either by drug injection or by physical exercise, heart rate and heart muscle oxygen demand is increased, and echocardiography is done simultaneously. During this time, segmental wall motion abnormality is sought; if present, it represents severe coronary artery stenosis supplying that segment. Besides detecting severe coronary stenosis, stress echocardiography is also used in aortic stenosis patients to determine the timing for surgery and in heart failure patients to determine the presence of viable tissue.
Myocardial Perfusion Scintigraphy (MPS)
MPS is similar to a stress test, and during this test, heart muscle oxygen demand is increased and perfusion of the heart muscle is calculated. If the perfusion defect is found in >10% of heart muscle territory, the patient is considered high risk for cardiac events and should undergo coronary angiography. Besides, MPS is also used to detect viable tissue in patients who have had heart attacks, so that we can decide whether opening the blocked
vessel is beneficial for the patient or not.
**Computed Tomography (CT) Coronary Angiography**
With the increase in slice numbers and the rate at which the CT scan slice is taken, the resolution is getting better. So CT angiography is widely used to see coronary anatomy. In patients with severe coronary calcification, the results might not be accurate. Therefore, the test should be ordered according to the patient’s age and the pretest probability of coronary artery disease.
**Coronary Angiography**
Coronary angiography is the gold standard diagnostic tool to diagnose coronary artery disease. Besides coronary arteries, it is also used to visualize carotid arteries, intracranial arteries, the aorta and its branches, upper and lower extremity arteries, renal arteries, pulmonary arteries, etc. With the help of contrast injection to the targeted vessel and visualization of the vessels using x-ray, angiography of a vessel is performed. This procedure is used both to diagnose and treat problems in the arterial vasculature.
**Right and Left Heart Catheterization**
Heart catheterization is used to measure pressures from different chambers of the heart, take biopsies of the myocardium to diagnose certain rare diseases, diagnose and classify pulmonary hypertension, and diagnose diseases like myocarditis, constrictive, and restrictive cardiomyopathy.
**Cardiac MRI**
Cardiac MRI is used to diagnose certain diseases that affect the myocardium of the heart (myocarditis, cardiomyopathies, infiltrative diseases), and diagnose the presence of scar tissue and hence the risk of death in certain high-risk patients. Cardiac MRI can provide static, dynamic, and functional information about the heart and valves and helps to determine abnormalities and diagnose diseases. Although cardiac MRI is getting popular day by day, its use in daily practice and in unstable patients is not feasible because of the time and expertise needed both to perform and interpret the test.
**Tilt Table Test**
Patients with recurrent episodes of syncope (fainting) but without any structural heart disease and obvious cause can be selected for a tilt table test to identify the cause and classify the type of syncope.