CVS – Radiology

On a normal chest X-ray, the right cardiac border is formed almost entirely by the:

✔ Right atrium

However — right atrium is NOT listed among the answer choices.
So from the given options, the closest and most reasonable structure is:

👉 Right ventricle

Even though:

• The right ventricle is the most anterior chamber,

• It does NOT normally form the right mediastinal border,

• The question forces you to choose the closest possible answer.

Why the others are incorrect

❌ Left atrial appendage
Forms part of the left cardiac border.

❌ Pulmonary trunk
Also part of the left upper mediastinal border.

❌ Left ventricle
Forms the left lower cardiac border.

❌ Aortic arch
Visible on the left as the “aortic knob.”

Correct anatomical teaching (important to remember):

Right border = Right atrium

Left border = Aortic arch → Pulmonary trunk → Left atrial appendage → Left ventricle

In this case:

• The patient is 18 years old, presenting with palpitations.

• He has a history of recurrent joint pain for 4 years, which raises suspicion for rheumatic heart disease (RHD) or another chronic inflammatory condition affecting the heart.

• On examination, a mild systolic murmur at the apex is present, suggesting possible mitral valve involvement.

• Vital signs show mild tachycardia but normal blood pressure.

Trans-thoracic echocardiography (TTE) is the investigation of choice because:

• It is non-invasive and safe in young patients.

• Provides detailed anatomical assessment of cardiac valves and chambers.

• Can detect valvular regurgitation or stenosis, chamber dilation, and any structural abnormalities that may explain both the murmur and palpitations.

• Particularly useful in suspected RHD given his chronic joint history (likely secondary to rheumatic fever).

❌ Why the other options are incorrect

Dobutamine stress echocardiography
Used to assess ischemia or contractile reserve in patients who cannot exercise. Not indicated in a young patient with likely structural/murmur-related pathology.

Exercise tolerance test
Primarily evaluates exercise-induced ischemia or arrhythmias. This patient’s history and murmur point more toward structural disease, not coronary artery disease.

Coronary angiography
Indicated for suspected coronary artery disease or acute coronary syndrome. Extremely unlikely in an 18-year-old with normal blood pressure and no chest pain.

Nuclear imaging
Used for myocardial perfusion or viability assessment. Not indicated here because the problem is structural, not ischemic.

1. Chest X-ray (CXR) (Correct Answer)

   • Why it’s the best option:
     • First-line investigation for assessing heart size.
     • Cardiothoracic ratio (CTR) is calculated:
       • Heart width ÷ Chest width (measured on a PA view).
       • CTR > 50% suggests cardiomegaly.
     • Simple, non-invasive, and widely available.
   • Confidential and quick, often done without extensive preparation.

2. Why the other options are incorrect:

   • High-Resolution Computed Tomography (HRCT) Scan:

     • Not typically used for diagnosing cardiomegaly.
     • Expensive and high radiation exposure.
     • More suited for detailed lung or mediastinal evaluation than heart size.

   • Clinical Exam:

     • Physical findings (like displaced apex beat) can suggest cardiomegaly, but they aren’t definitive.
     • Cannot confirm heart size without imaging.

   • Electrocardiography (ECG):

     • Can show voltage criteria for hypertrophy, but ECG changes are not always reliable for diagnosing an enlarged heart.
     • Doesn’t measure the actual size of the heart.

   • Echocardiography:

     • Excellent for evaluating heart function and chamber size, but:
     • More specialized and operator-dependent.
     • Not typically used for routine heart size assessment.

Conclusion:
A chest X-ray remains the most practical, non-invasive, and widely used tool for confidentially diagnosing cardiomegaly, based on the cardiothoracic ratio.

Mitral valve stenosis is most commonly caused by rheumatic heart disease, leading to narrowing of the mitral valve opening, which restricts blood flow from the left atrium to the left ventricle. The gold standard for diagnosing mitral valve stenosis is an echocardiogram (ECHO) because:

• Transthoracic echocardiography (TTE) provides a detailed view of valve morphology, leaflet thickening, calcification, and mobility.
• Doppler echocardiography measures mean transvalvular pressure gradient and mitral valve area, essential for assessing stenosis severity.
• Transesophageal echocardiography (TEE) may be used for better visualization, especially when looking for left atrial thrombus.

Thus, echocardiography is the most accurate and widely used method to diagnose mitral stenosis.

Why the Other Options Are Incorrect:

1. Cardiac catheterization (Incorrect)

   • Previously used for hemodynamic assessment, but echocardiography has largely replaced it due to its non-invasive nature.
   • Catheterization is now reserved for cases requiring intervention (e.g., balloon valvuloplasty).

2. Angiography (Incorrect)

   • Coronary angiography evaluates coronary artery disease, not valvular stenosis.
   • It does not provide direct information about mitral valve structure or function.

3. Electrocardiogram (ECG) (Incorrect)

   • ECG may show atrial enlargement (P mitrale) or atrial fibrillation, but it cannot directly assess the mitral valve.

4. Magnetic Resonance Imaging (MRI) (Incorrect)

   • Cardiac MRI can assess chamber size and function, but it is not the first-line or gold standard for mitral stenosis.

Why “Right Atrium” is the Correct Answer:

• The right atrium is located on the rightmost side of the heart and receives venous return from the superior vena cava (SVC) and inferior vena cava (IVC).
• In a PA view, the right atrium forms the right cardiac border because it is closest to the right lung field.
• The superior vena cava (SVC) also contributes to the upper portion of the right cardiac border.

Why the Other Options Are Incorrect:

1. Right Ventricle – Incorrect

   • The right ventricle forms the anterior surface of the heart, but it does not contribute to the right border on a PA chest X-ray.
   • Instead, it is located centrally, close to the sternum.

2. Left Atrium – Incorrect

   • The left atrium is located posteriorly, behind the right atrium.
   • On a PA chest X-ray, it does not contribute to the right border; instead, it contributes to the upper posterior part of the left heart border.

3. Pulmonary Trunk – Incorrect

   • The pulmonary trunk arises from the right ventricle and is positioned superiorly, but it does not form the right heart border.
   • It is more visible on lateral X-ray views or if it is pathologically enlarged.

4. Right Pulmonary Artery – Incorrect

   • The right pulmonary artery passes behind the ascending aorta, supplying the right lung.
   • It does not contribute to the right heart border on a PA chest X-ray.

Why Chest X-ray (Posteroanterior view) is Correct:
A chest X-ray (posteroanterior view) is the most appropriate and cost-effective initial investigation for evaluating cardiomegaly (enlargement of the heart). It provides a clear image of the heart’s silhouette and can help determine the overall size of the heart and identify specific chamber enlargement based on the shape and contours of the cardiac shadow.

• Cost-effectiveness: Chest X-ray is widely available, inexpensive, and requires minimal resources compared to advanced imaging techniques.
• Utility: It is a first-line screening tool for cardiomegaly and can also provide additional information about the lungs and thoracic structures, which may be relevant in the context of cardiac enlargement.

Why the Other Options Are Incorrect:

1. Nuclear Scan:
   Nuclear scans (e.g., myocardial perfusion imaging) are used to assess blood flow to the heart muscle and diagnose ischemic heart disease. They are not suitable for evaluating the size of the heart or identifying specific chamber enlargement. Additionally, they are expensive and involve radiation exposure.
2. Contrast-enhanced Computerized Tomography (CT) Scan:
   While CT scans can provide detailed images of the heart and its chambers, they are not cost-effective for initial evaluation of cardiomegaly. CT scans are typically reserved for specific indications, such as evaluating coronary arteries or complex congenital heart disease.
3. Cardiac Magnetic Resonance Imaging (MRI):
   Cardiac MRI provides highly detailed images of the heart’s structure and function, including chamber size and wall motion. However, it is expensive, time-consuming, and not widely available. It is typically used for complex cases or when other imaging modalities are inconclusive.
4. Doppler Echocardiography:
   Doppler echocardiography is an excellent tool for evaluating heart size, chamber dimensions, and function. However, it is not a radiological investigation (it uses ultrasound) and is typically performed after initial screening with a chest X-ray. While highly informative, it is more specialized and may not be as cost-effective as a chest X-ray for initial screening.

Why Coronary Angiography is Correct:
The patient presents with typical symptoms of acute coronary syndrome (ACS), including chest pain radiating to the left arm, vomiting, and ST-segment elevation in the inferior ECG leads (II, III, and aVF). These findings are highly suggestive of an ST-elevation myocardial infarction (STEMI), which is a medical emergency requiring immediate intervention.

Coronary angiography is the most appropriate test in this scenario because it provides direct visualization of the coronary arteries, identifies the location and severity of the blockage, and allows for immediate therapeutic intervention (e.g., percutaneous coronary intervention or PCI) to restore blood flow. Coronary angiography is the gold standard for diagnosing and managing STEMI.

Why the Other Options Are Incorrect:

1. Nuclear Imaging:
   Nuclear imaging (e.g., myocardial perfusion scans) is used to assess blood flow to the heart muscle and diagnose ischemic heart disease. However, it is not appropriate in the acute setting of STEMI, where immediate coronary angiography is required for definitive diagnosis and treatment.
2. Exercise Tolerance Test:
   This test is used to evaluate for coronary artery disease in stable patients with atypical symptoms or risk factors. It is contraindicated in patients with acute chest pain and ST-segment elevation, as it could worsen the condition.
3. Trans-thoracic Echocardiography (TTE):
   TTE is useful for assessing cardiac structure and function, such as wall motion abnormalities or complications of myocardial infarction (e.g., mitral regurgitation or ventricular septal defect). However, it does not provide direct information about coronary artery blockages and is not the first-line test for STEMI.
4. Dobutamine Stress Echocardiography:
   This test is used to evaluate for ischemic heart disease in stable patients or assess myocardial viability. It is not appropriate in the acute setting of STEMI, where immediate coronary angiography is indicated.

Why Trans-thoracic Echocardiography (TTE) is Correct:
The patient is an 18-year-old male with palpitations, a history of joint pain, and a mild systolic murmur in the apical area. These findings raise suspicion for rheumatic heart disease (RHD), a condition that can develop after untreated or recurrent streptococcal infections (e.g., rheumatic fever). RHD often affects the heart valves, particularly the mitral valve, leading to murmurs and palpitations.

Trans-thoracic echocardiography (TTE) is the most appropriate initial investigation because it provides detailed imaging of the heart’s structure and function, including the valves. It can confirm the presence of valvular abnormalities (e.g., mitral regurgitation or stenosis) and assess the severity of the condition. TTE is non-invasive, widely available, and highly effective for diagnosing structural heart disease, which is likely in this case.

Why the Other Options Are Incorrect:

1. Exercise Tolerance Test:
   This test is used to evaluate for coronary artery disease (CAD) or assess exercise capacity in patients with known heart disease. However, this patient is young and has no risk factors for CAD. His symptoms (palpitations and joint pain) and findings (systolic murmur) are more suggestive of valvular heart disease, not ischemic heart disease.
2. Nuclear Imaging:
   Nuclear imaging (e.g., myocardial perfusion scans) is primarily used to assess blood flow to the heart muscle and diagnose ischemic heart disease. This is not relevant to a young patient with valvular heart disease and no symptoms of ischemia.
3. Coronary Angiography:
   Coronary angiography is an invasive procedure used to diagnose coronary artery disease. It is not indicated in this case because the patient’s symptoms and findings are not consistent with CAD. Additionally, coronary angiography is not the first-line investigation for valvular heart disease.
4. Dobutamine Stress Echocardiography:
   This test is used to evaluate for ischemic heart disease or assess myocardial viability in patients with known CAD. It is not appropriate for this patient, as his symptoms and findings point toward valvular heart disease rather than ischemia.

Echocardiography is a non-invasive imaging technique that uses ultrasound waves to assess the structure and function of the heart. However, it does not directly measure the electrical activity of the heart, which is instead evaluated using an electrocardiogram (ECG or EKG).

What Echocardiography is Used For:

✅ Systolic Function – Measures ejection fraction (EF) and myocardial contractility, helping diagnose heart failure and cardiomyopathies.

✅ Diastolic Function – Evaluates ventricular relaxation and filling pressures, crucial for detecting diastolic heart failure.

✅ Valvular Function – Assesses valve motion, stenosis, and regurgitation (e.g., aortic stenosis, mitral regurgitation).

✅ Diagnosis of Heart Defects – Used to detect congenital heart defects, such as atrial septal defects (ASD) or ventricular septal defects (VSD).

Why the Correct Answer is Right:

✔ Electrical activity of the heart – Correct. Echocardiography does not provide information about the heart’s electrical activity. Instead, an ECG (electrocardiogram) is used to assess arrhythmias, conduction abnormalities, and other electrical disturbances.

Why the Other Options Are Incorrect:

❌ Systolic functions – Incorrect. Echocardiography is commonly used to assess ventricular contraction, ejection fraction (EF), and stroke volume.

❌ Valvular functions – Incorrect. Echocardiography is the gold standard for evaluating valvular diseases such as stenosis and regurgitation.

❌ Diastolic functions – Incorrect. Echocardiography helps assess ventricular relaxation, compliance, and filling pressures, which are critical in diagnosing diastolic dysfunction.

❌ Diagnosis of heart defects – Incorrect. Congenital and acquired heart defects (e.g., septal defects, patent ductus arteriosus) are diagnosed using echocardiography, often with Doppler imaging.

In reversible ischemia, thallium SPECT (Single Photon Emission Computed Tomography) imaging shows a defect at stress that resolves at rest. Here’s why:

• Mechanism of Reversible Ischemia:
  • Reversible ischemia occurs when there is a temporary reduction in blood flow to a region of the heart during stress (e.g., exercise or pharmacological stress), but blood flow is restored at rest.
  • This is typically caused by coronary artery disease, where narrowed arteries cannot supply sufficient blood during increased demand but can meet the demand at rest.
• Thallium SPECT Findings:
  • Stress Images: A perfusion defect is seen in the ischemic area because thallium-201 (a radioactive tracer) is not delivered adequately to the affected region during stress.
  • Rest Images: The defect resolves because blood flow is restored at rest, and the tracer redistributes to the previously ischemic area.
• Clinical Significance:
  This pattern of defect at stress and normal at rest is characteristic of reversible ischemia and helps differentiate it from fixed defects (e.g., scar tissue from a previous myocardial infarction).

Why the Other Options Are Incorrect:

1. Defect at stress:
   While a defect at stress is part of the finding, it does not fully describe reversible ischemia, which also requires normalization at rest.
2. No change:
   No change between stress and rest images would indicate normal perfusion, not ischemia.
3. Defect at rest:
   A defect at rest suggests a fixed perfusion defect, such as scar tissue from a previous infarction, not reversible ischemia.
4. Defect at stress and rest:
   A defect at both stress and rest indicates a fixed defect, such as myocardial scarring, not reversible ischemia.

A myocardial perfusion test is a diagnostic procedure used to evaluate blood flow to the heart muscle (myocardium). The most common method involves imaging the heart at rest and after exercise (or pharmacological stress). Here’s why:

• Purpose of Myocardial Perfusion Imaging:
  This test helps identify areas of the heart that are not receiving adequate blood flow, which may indicate coronary artery disease (CAD).
• How It Works:
  1. Resting Imaging: A radioactive tracer (e.g., technetium-99m or thallium-201) is injected into the bloodstream, and images are taken to assess blood flow to the heart at rest.
  2. Stress Imaging: The patient is then subjected to exercise (e.g., treadmill) or pharmacological stress (e.g., adenosine or dobutamine) to increase heart demand. Another dose of the tracer is injected, and images are taken to assess blood flow under stress conditions.
• Comparison of Rest and Stress Images:
  By comparing the images taken at rest and after stress, doctors can identify areas of the heart with reduced blood flow, which may indicate blockages in the coronary arteries.

Why the Other Options Are Incorrect:

1. Imaging immediately after eating food:
   Eating food does not provide the controlled stress needed to evaluate myocardial perfusion. This is not a standard part of the test.
2. Imaging at rest:
   While imaging at rest is part of the myocardial perfusion test, it is not sufficient on its own. The test requires comparison with stress imaging to assess blood flow under different conditions.
3. Imaging after losing 5 kg weight:
   Weight loss is not relevant to myocardial perfusion testing. The test focuses on blood flow to the heart, not body weight.
4. None of these:
   This option is incorrect because imaging at rest and after exercise is indeed a myocardial perfusion test.

The ascending aorta is the initial portion of the aorta that arises directly from the left ventricle of the heart and carries oxygenated blood to the systemic circulation. It is the first part of the aorta before it curves into the aortic arch. The branches that originate from the ascending aorta are the coronary arteries and the brachiocephalic trunk (on the right side only).

• Brachiocephalic artery: This is the first branch of the aortic arch, but it originates from the ascending aorta. It bifurcates into the right subclavian artery and the right common carotid artery. So, if the ascending aorta is involved (as in an aneurysm), the brachiocephalic artery would be affected.

• Coronary arteries: The left and right coronary arteries arise from the ascending aorta just above the aortic valve. These arteries supply blood to the myocardium (heart muscle). Therefore, an aneurysm of the ascending aorta would affect these arteries as well.

Why the Other Options Are Incorrect:

• Posterior intercostal arteries: These arteries arise from the thoracic aorta, which is a continuation of the aortic arch and lies below the level of the ascending aorta. Therefore, the posterior intercostal arteries are not branches of the ascending aorta.

• Common carotid arteries: The common carotid arteries arise from the brachiocephalic trunk (on the right side) and directly from the aortic arch (on the left side), not the ascending aorta. Therefore, these arteries are not branches of the ascending aorta.

• Bronchial arteries: The bronchial arteries arise from the thoracic aorta and supply the bronchi and lungs. They are not branches of the ascending aorta.

Conclusion:

The ascending aorta gives rise to the coronary arteries (supplying the heart) and the brachiocephalic artery (on the right side), which further divides into the right common carotid and right subclavian arteries. These are the arteries affected by an aneurysm of the ascending aorta.

The gold standard for diagnosing mitral valve stenosis (MVS) is echocardiography, specifically Doppler echocardiography.

Mitral valve stenosis is characterized by narrowing of the mitral valve orifice, leading to restricted blood flow from the left atrium to the left ventricle. The most common cause is rheumatic heart disease.

Why is Echocardiography the Gold Standard?

• Transthoracic echocardiography (TTE):

  • Measures mitral valve area (normal: 4–6 cm², severe stenosis: <1.5 cm²).
  • Identifies thickening, calcification, and reduced mobility of mitral valve leaflets.
  • Detects left atrial enlargement and signs of pulmonary hypertension.

• Doppler echocardiography:

  • Determines pressure gradients across the mitral valve.
  • Measures mitral inflow velocity to assess stenotic severity.

• Transesophageal echocardiography (TEE) (if needed):

  • Provides higher-resolution imaging, particularly useful in assessing thrombus formation in the left atrial appendage (a complication of mitral stenosis).

Why Are the Other Options Incorrect?

1. Electrocardiography (ECG) (Incorrect)

• ECG may show left atrial enlargement (broad/notched P wave in lead II, biphasic P wave in V1) and signs of atrial fibrillation, which is common in MVS.
• However, ECG does not confirm the diagnosis or assess the severity of mitral stenosis.

2. Troponin I Test (Incorrect)

• Troponin I is a biomarker for myocardial infarction (MI), not structural valvular abnormalities.
• Mitral stenosis does not directly cause myocardial injury, so troponin levels remain normal unless a secondary complication (e.g., atrial thromboembolism leading to infarction) occurs.

3. Creatine Kinase-MB (CK-MB) Test (Incorrect)

• CK-MB is another cardiac enzyme marker used in myocardial infarction.
• It is not useful in diagnosing valvular disease like mitral stenosis.

4. Computed Tomography (CT) Scan (Incorrect)

• CT imaging may visualize mitral valve calcification, but it is not the preferred method for functional assessment.
• CT does not provide real-time hemodynamic data or Doppler flow analysis, making it inferior to echocardiography for diagnosing mitral stenosis.

The cardiothoracic ratio (CTR) is a measurement that compares the width of the heart to the width of the chest on a PA chest radiograph. It’s used to assess whether the heart is enlarged (cardiomegaly).   

• How to Calculate CTR:

  • Measure the widest horizontal diameter of the heart.
  • Measure the widest horizontal diameter of the thoracic cavity (inner rib margins).
  • Divide the heart width by the chest width.
  • Express the result as a percentage.

• Normal CTR: In adults, a normal CTR is generally considered to be less than 50%. This means that the heart should occupy less than half the width of the chest.

Why the other options are incorrect:

• < 40%: While a CTR less than 40% would certainly be within normal limits, the standard upper limit of normal is 50%.
• < 30%: This would indicate a very small heart, which is not a typical finding in healthy adults.
• > 60% and > 50%: A CTR greater than 50% is indicative of cardiomegaly, suggesting enlargement of the heart. A CTR over 60% would be a very significant enlargement.

Echocardiography (Echo) is a non-invasive imaging technique that uses ultrasound waves to visualize the structure and function of the heart. It provides information about:

1. Structural deformities:

   • Valvular defects (e.g., mitral stenosis, aortic regurgitation)
   • Congenital heart defects (e.g., atrial septal defect, ventricular septal defect)
   • Cardiac chamber size and wall thickness
   • Pericardial effusion and cardiac masses

2. Physiological deformities:

   • Ejection fraction and cardiac output
   • Valve function and blood flow abnormalities (using Doppler echocardiography)
   • Diastolic dysfunction (e.g., restrictive cardiomyopathy)

Thus, echocardiography provides information about both structural and physiological abnormalities, making it a crucial tool for diagnosing various cardiac conditions.

Why the Other Options Are Incorrect

• Provides same information as EKG:

  • Incorrect – An EKG (electrocardiogram) evaluates electrical activity, while echocardiography provides structural and functional details of the heart.

• Provides information about physiological deformities:

  • Partially correct – While echocardiography does assess functional abnormalities, it also evaluates structural defects, making this option incomplete.

• Provides information about structural deformities:

  • Partially correct – Echo does reveal structural abnormalities, but it also detects functional (physiological) abnormalities, making this option incomplete.

• None of these:

  • Incorrect – Echocardiography provides both structural and functional information, making it a valuable diagnostic tool.

Kerley lines are the most telling sign of congestive heart failure (CHF) on a chest X-ray because they indicate interstitial pulmonary edema caused by increased pulmonary venous pressure.

There are three types of Kerley lines, which are seen due to fluid accumulation in the interlobular septa:

• Kerley A lines – Longer, radiate from the hilum, representing fluid in the deep interlobular septa.
• Kerley B lines – Short, horizontal lines near the lung bases, most commonly seen in CHF.
• Kerley C lines – Reticular (net-like) pattern due to widespread interstitial edema.

These lines are a hallmark of pulmonary congestion in CHF and indicate fluid overload in the lungs.

Why the Other Options Are Incorrect

• Upper lobar congestion:

  • Also seen in CHF due to cephalization (redistribution of blood to upper lung zones), but it is not as specific as Kerley lines.

• Thickened interstitium:

  • Thickening of the interstitium can occur in CHF but is also seen in interstitial lung diseases like pulmonary fibrosis, making it less specific.

• Cardiomegaly:

  • An enlarged heart silhouette is a feature of CHF, but it can also be due to hypertension, pericardial effusion, or cardiomyopathy.
  • It supports CHF diagnosis but is not as direct as Kerley lines for pulmonary congestion.

• Hilar congestion:

  • Enlargement of the pulmonary vessels around the hilum is common in CHF, but it can also be seen in other conditions like pulmonary hypertension.