Investigations To Be Performed In Cardiac Disorders

Abstract

The investigations for CVD (Cardiovascular disease) are different according to the condition and depend on a complex combination of clinical and pathological data. This study aims to assess the prevalence or risk factors of heart disease using specific diagnostic methods, such as electrocardiograms (ECG), echocardiograms, or coronary angiography, often analyzing patient data like demographics, medical history, and lifestyle factors, to identify patterns or potential interventions for early detection and improved management of cardiovascular disease.

Introduction

There are so many people these days suffering from heart diseases, even the younger generation, and the study shows that people having heart diseases vary from 1.6% to 7.4% in rural populations and from 1% to 13.2% in urban populations. Heart disease is diagnosed using a variety of tests that assess the heart’s electrical activity, blood flow, and structure. These tests can help determine the cause of heart conditions. In males, there is more possibility of heart attack because of low levels of estrogen and progesterone hormone as compared to females which affect cardiovascular health. There are different types of tests done to rule out a cardiac disease like ECG (electrocardiogram), echocardiogram, coronary angiography, blood tests like lipid profile, troponin test, NT-proBNP levels, etc.

Blood Tests For Cardiac Disorders

• The NT-proBNP test measures the levels of NT-proBNP in your blood. NT-proBNP is a protein produced by the heart. The test helps determine if your blood levels of NT-proBNP are within the normal range for a healthy person.
• Normal range: Under 75 years old –
• Natriuretic peptides: Natriuretic peptides are the hormones secreted by myocardial cells of the atrium and BNP (B-type natriuretic peptide/Brain natriuretic peptide) secreted by myocardial cells of the ventricles that regulate the cardiovascular system. They are activated during heart failure and help protect the heart and its tissues. There are some types of natriuretic peptides.

1. Atrial natriuretic peptide (ANP): Decreases blood pressure and cardiac hypertrophy. Normal range: 6.1 – 8.6 ng/L.
2. Brain natriuretic peptide (BNP): Reduces ventricular fibrosis. Normal range: Below 100 pg/mL.
3. C-type natriuretic peptide (CNP): Suppresses neo-intima formation after injury. Normal range: 0.4 – 1.0 pmol/L.
4. Urodilatin (URO): Regulates water and sodium levels. Normal range: Below 100 pg/mL.
5. Dendroaspis natriuretic peptide (DNP): Lowers blood pressure via vasodilation. Normal range: 2 – 11 pg/mL.

The Function of Natriuretic Peptides

Natriuretic peptide regulates sodium and water balance, regulate blood volume, arterial pressure, and aldosterone release, increase glomerular filtration rate (GFR), produce natriuresis and diuresis, lipid oxidation, and ameliorate insulin sensitivity.

• Plasma Ceramides: High levels of ceramides in the blood are a sign of a higher risk of heart disease as it is a type of lipid molecule found in blood plasma having various cellular processes, related to inflammation and cell death, increased biomarker for cardiovascular disease risk when levels are elevated. It also indicates the disruption of blood flow due to plaque collection in the arteries.

Normal Range – Lower: 0–2, Moderate: 3–6, Increased: 7–9, Higher: 10–12.

• Complete Blood Count (CBC) – Measures red and white blood cells, platelets, and hemoglobin.
• Normal range – RBC (Red blood cells) is 4.7 to 6.1 cells/mcL for males and 4.2 to 5.4 cells/mcL for females, WBC (White blood cell) – between 4,500 and 11,000, Platelets count – 150000 to 450000 per microliter of blood. and hemoglobin level range for men is 13.5–17.5 grams per deciliter (g/dL), and for women, it’s 12.0–15.5 g/dL.
• Electrolytes, urea, and creatinine – Helps identify electrolyte disturbances and urea levels help monitor kidney function, while electrolytes help stabilize heart rhythm.

Normal range – Sodium: 135–145 mmol/L, Potassium: 3.6–5.5 mmol/L, Calcium: 8.8–10.7 mg/dL, Chloride: 97–105 mmol/L, Magnesium: 1.5–2.6 mg/dL, Phosphate: 3.4–4.5 mg/dL, Bicarbonate: 22–29 mmol/L, Blood Urea Nitrogen (BUN): should range from 6-24 mg/dL and Creatinine: 0.7 to 1.2 mg/dL are the normal values.

• Troponin – Measures the amount of protein released into the blood when the heart muscle is damaged. Two types of this protein are Troponin-I and Troponin -T.

Normal range – Troponin-I value is below 0.4 ng/mL and the value of Troponin-T is 0.01 ng/mL. Elevated levels indicate potential heart muscle damage, often associated with a heart attack.

Appropriate time to be performed – To get the best results of Troponin T and I test should be done between 3 to 12 hours after the onset of chest pain.

• Creatine kinase myocardial band – a specific type of creatine kinase enzyme called “CK-MB” (Creatine Kinase-MB), which is primarily found in the heart muscle and is used as a marker to detect potential damage to the heart muscle, particularly during a heart attack; when the heart muscle is injured, elevated levels of CK-MB are released into the bloodstream. Should be correlated with other cardiac markers also like ECG and clinical signs.

Normal range – The normal range for creatine kinase myocardial band (CK-MB) levels in the blood is 5 to 25 international units per liter (IU/L). CK-MB components should be done within a few hours of symptom onset, typically within 3-6 hours to capture the rising levels of the enzyme which indicate potential heart muscle damage; peak levels are usually seen between 12-24 hours after the event.

• Aspartate aminotransferase (AST) – AST (Aspartate aminotransferase) is an enzyme found in the heart muscle, and its release into the bloodstream increases when heart tissue is damaged; however, due to its presence in other organs like the liver, a high AST alone isn’t definitive proof of a heart attack and should be interpreted alongside other cardiac markers.

Normal Range – Aspartate aminotransferase (AST) in a patient experiencing a myocardial infarction (MI) is typically considered to be between 0 and 35 units per liter (U/L). Activity typically exceeds the normal range within 8–12 h of the onset of a myocardial infarction, and returns to normal within 3–4 days.

• Cholesterol: A higher amount of cholesterol can indicate a risk of heart disease. A high cholesterol level will lead to a collection of plaque in the arteries and can cause blockages, Ischaemic heart disease or thrombotic heart failure, atherosclerosis, coronary artery diseases, etc.

Normal Range – Normal – 0-150 mg/dL, Borderline high – 150 – 199 mg/dL, High – 200 – 499 mg/dL, and very high is above 500mg/dL.Other cholesterol measurements LDL (bad cholesterol or Low-density lipoproteins): About 100 mg/dL and HDL (good cholesterol/High-density lipoproteins): At least 40 mg/dL in men and 50 mg/dL in women.

• Triglycerides: High levels of triglycerides may increase the risk of heart disease. Triglycerides also cause plaque collection in the arteries and cause atherosclerosis in the arteries.

Normal values – Less than 150 mg/dL

• C-reactive protein (CRP): A protein linked to inflammation in the body. High levels of CRP indicate a higher risk of heart disease and inflammation in the arteries. The normal range shows the inflammation in the body, so with CRP other cardiac markers should be notes and also clinical signs of the patient.

Normal Range – Less than 0.3 mg/dL: Normal level for most healthy adults,0.3 to 1.0 mg/dL: Normal or minor elevation,1.0 to 10.0 mg/dL: Moderate elevation, More than 10.0 mg/dL: Marked elevation, More than 50.0 mg/dL: Severe elevation.

• Glucose: Measures the level of sugar in the blood. elevated blood sugar can directly damage blood vessels, impair the heart’s ability to efficiently utilize energy, and lead to changes in the heart muscle structure, ultimately causing issues like decreased contractility and increased risk of heart failure.

Normal Range – 80 to 120 is the value of Random blood sugar and the value of HbA1C is below 5.7%. (of last 3 months)

Imaging Test

There are different types of imaging tests commonly used to diagnose any cardiac-related disorders which include X-ray chest (PA view / posterior-anterior view), Echocardiogram (Echo), Cardiac magnetic resonance imaging (MRI), Coronary computed tomography angiography (CTA), coronary angiography (an invasive procedure using a catheter to visualize coronary arteries), TMT (Treadmill test/exercise stress test).

Treadmill’s Test (TMT)

It is a diagnostic procedure that evaluates the heart’s response to physical exertion. It’s also known as an Exercise Stress Test. This test is used for detecting abnormal heart rhythms (arrhythmias), Diagnosing coronary artery diseases, Evaluating the heart’s ability to handle exertion during exercise.

How it’s performed

• The patient walks on a treadmill or pedals on a bicycle.
• The treadmill’s speed and incline increase gradually.
• The patient’s heart rate, blood pressure, and electrocardiogram (ECG) are monitored.
• The test is stopped if the patient experiences chest pain, shortness of breath, or fatigue.

ECG (Electrocardiogram)

It is a non-invasive test that measures the electrical activity of your heart. It can help diagnose heart conditions like abnormal heart rhythms and coronary heart disease.

How it works

• Electrodes are placed on your chest, arms, and legs.
• The electrodes are connected to an ECG machine by wires.
• The machine records and analyzes the electrical activity of your heart.

What an ECG shows

• Heart rate: The number of times the heart beats per minute
• Heart rhythm: Whether the heart is beating consistently and evenly
• Wave patterns: The P wave, QRS complex, ST segment, and T wave indicate different stages of the heart’s electrical activity.
• ECG can show severe emergencies like MI (Myocardial infarction), STEMI (ST wave elevation myocardial infarction), NSTEMI (non-ST wave elimination myocardial infarction), RBBB (Right bundle branch blockage), LBBB (Left bundle branch blockage), Hypokalemia, Hyperkalemia, Stroke, Atrial arrhythmia, arterial enlargement, atrial fibrillation, etc.

Echocardiogram – Echocardiogram is a medical imaging test that uses ultrasound to visualize the heart. It has other types like –

1. 2D- Echo (2 Dimensional echocardiogram) – Used to detect heart function and structure and to detect abnormalities like blockages, Congenital heart failure etc.
2. 3D- Echo (3-Dimensional Echocardiogram) – Provides more detailed images of the heart, especially the lower left chamber. Heart structure, in 3D echocardiograms, shows the heart’s walls, valves, and large vessels. Heart function as 3D echocardiograms can show how well the heart pumps blood. Blood flow, 3D echocardiograms can show the speed and direction of blood flow in the heart and vessels.
3. Doppler echocardiogram – A Doppler echocardiogram can measure the speed and direction of blood flow through the heart chambers and valves, helping to identify issues like valve leaks (regurgitation), narrowed valves (stenosis), and abnormal blood flow patterns.
4. Color Doppler – Most Doppler echocardiograms utilize “color Doppler” imaging, where different colors on the screen represent the direction of blood flow (red for blood moving towards the probe, blue for blood moving away).
5. How it works – The test relies on the Doppler effect, which is the change in frequency of a sound wave when the source of the sound is moving relative to the observer. Then the machine will calculate blood flow velocity based on the shift in ultrasound waves reflected from moving blood cells.
6. Color flow imaging test (CFI) / Triplex ultrasound – CFI is an enhanced form of Doppler ultrasound that shows blood flow in the heart in color. Checking for blood flow issues like clots or blockages, testing for deep vein thrombosis (DVT), evaluating blood flow after a stroke, and monitoring blood flow to organs like the heart, kidneys, and liver.
7. How to perform – During the test, a technician applies a gel to the chest and moves a transducer over the chest wall to capture ultrasound images of the heart.
8. Major findings in Echo test – The findings in Echo shows the left ventricle, left atrium, right atrium , right ventricle, pericardium, mitral valve, aortic valve, pulmonary valve and tricuspid valve condition.

In the left ventricle, it shows reading like –

1. EDD (End diastolic diameter) – It means the end of the diastolic diameter of the left ventricle after the diastolic movement.
2. IVS (Interventricular septum) – Interventricular septum means a septum that separates the left and right ventricles of the heart and which refers to the thickness of the interventricular septum and its end-diastolic pressure.
3. Ejection fraction – This means the measurement of how much blood the left ventricle of the heart pumps out with each beat, which is most commonly seen in Echo. The values of LVEF (Left Ventricle Ejection Fraction) between 50% to 70% are normal, and RVEF (Right Ventricle Ejection Fraction) normal value is 40%. This means the heart pumps out 50-70% of blood in the left ventricle and 40% in the right ventricle with each beat. Mildly reduced LVEF is 40% to 49%, reduced LVEF is 40% or less, and hyperdynamic LVEF is greater than 75%.
4. FS (Fractional shortening) – It means that the left ventricle’s size reduces during contraction, essentially showing how much the ventricle shortens when it pumps blood out. A normal FS for the left and right ventricle is considered to be between 25% – 45%.
5. Mitral valve – It’s a valve between two chambers on the left side of the heart. It opens so that blood can flow from the upper chamber of the heart (left atrium) to the lower chamber (left ventricle), and it closes to keep blood from flowing back. Normal ranges are 4 to 6 cm², mild stenosis 1.5-2.5 cm², moderate stenosis 1.5 cm², and severe stenosis 1 cm².
6. Tricuspid valve – This valve separates the right atrium from the right ventricle, having three flaps that open and close to allow blood to flow in one direction. Its normal values are 3.1 to 4.0 cm in diameter.
7. Aortic valve – It’s a valve present between the left ventricle and the aorta, which controls blood flow from the heart to the body. Normal values are 2.5 to 4.5 cm².
8. Pulmonary valve – It is a heart valve that controls the flow of blood from the right ventricle to the lungs. Normal values are 3 cm².

Coronary CT Angiography – Coronary CT Angiography is a non-invasive 3D scan that uses X-rays and computer technology to check for blockages in the heart’s coronary arteries. It’s also known as coronary computed tomography angiography. Used To check for narrowed or blocked arteries in the heart and for the calcification of the arteries to look for other heart conditions and to determine whether someone needs cardiac catheterization.

How to perform – A dye is injected into a vein in your arm or hand which is iodine-based contrast material, The patient lies on a table that slides into a CT scanner. The CT scanner takes images from multiple angles. Takes almost 20 min.

Coronary angiography – A coronary angiography is an invasive procedure where a catheter is threaded into a blood vessel in the groin or wrist and used to inject contrast dye directly into the coronary arteries to visualize them using X-ray fluoroscopy to examine the heart’s blood vessels.

When coronary angiography and coronary CT angiography is advised – This test is advised when there is atherosclerosis (plaque collection in the arteries which decrease the flow of blood in the arteries), when coronary artery disease is there, the narrowing (less than 50%) in any of the coronary arteries is considered normal, coronary angioplasty with stent placement is done to open the blocked artery using a balloon catheter, or coronary artery bypass surgery (CABG) where healthy blood vessel is used to bypass the blockage. Angioplasty and stent (small mesh tube) is done where there is blockage in the artery threading a catheter with a balloon into the blocked artery, inflating the balloon to open the blockage and putting a small mesh tube to keep the artery open.

X-ray chest – Here the Posteroanterior view is taken to check the shape and size location of the heart lungs vessels and airway. some results can be seen in the x-ray as follows:

• Heart size and shape: A chest X-ray can show if the heart is enlarged or has an unusual shape.
• Heart failure: A chest X-ray can show signs of heart failure.
• Valve disorders: A chest X-ray can help confirm the presence of a valve disorder.
• Fluid in the lungs: A chest X-ray can show if there is fluid in the lungs, which could be a sign of heart disease.

How to perform – The patient is told to remove the cloth or any metal chain in the neck region then the person is told to take a deep breath and hold and in between the machine takes the image of the chest, then the person is told to release the breath and told to wear the belongings.

Cardiac magnetic resonance imaging (MRI) – It’s a non-invasive scan that uses radio waves and a magnetic field to create detailed images of the heart and blood vessels. This is used in various diseases like congenital heart diseases, heart valve diseases, evaluating heart size and function, arrhythmia, etc.

How it’s performed – The patient lies on a bed that slides into a tunnel-shaped scanner, and then the patient is told to lie still with the least body movements. The scan lasts 15 to 90 minutes.

MUGA Test (Multi-gated Acquisition)

• A non-invasive scan that uses radioactive tracers to create images of the heart.
• Can be used to assess the structure of the heart and measure how much blood it pumps after a contraction.

How to perform – A small amount of radioactive tracer is injected into the bloodstream through an IV, the tracer attaches to red blood cells a gamma camera is placed over the chest to capture images of the heart, the camera takes pictures of the heart during each heartbeat and the images show how well the heart pumps blood and if any areas of the heart muscle aren’t contracting normally.

Genetic testing:

• Targeted gene panel testing: This is the most common approach, where a group of genes known to be associated with a specific heart condition are analyzed.
• Exome sequencing: This method sequences all protein-coding genes in the genome, which can be useful when the suspected genetic cause is unknown or when multiple genes might be involved.
• Whole genome sequencing: This analyzes the entire genome, but is usually only used in research settings due to the high cost and complex data analysis.

Conclusion

Cardiovascular diseases are the most common diseases in India. After the COVID-19 pandemic, a study shows there has been a rapid increase in cardiac cases all over India. Even youngsters are also prone to heart attack and most people are unaware of the condition that they have any cardiac diseases. To avoid this we need to be aware of the population regarding the severity of diseases and the effect they have on society. For awareness, camps educating people and doing tests for the urban and rural populations should be done at heart health camps and heart health management should be guided to everyone.