Point-of-Care Cardiac Ultrasound — MCQs
Pulse echo principle is used by which modality?
A patient presents with engorged neck veins, a blood pressure of 80/50 mmHg, and a pulse rate of 100 beats per minute following blunt trauma to the chest. The diagnosis is:
The imaging modality primarily used in FAST (Focused Assessment with Sonography for Trauma) exam is:
Which of the following does not form the left border of the heart?
A young female presents with chest pain not associated with exercise. Auscultation reveals multiple ejection clicks with a murmur. The most important investigation for diagnosis is:
Which among the following is the best method to assess adequacy of fluid resuscitation in a polytrauma patient:
Which chamber enlargement shows a double right heart border with a wide subcarinal angle?
The earliest crown-rump length (CRL) at which cardiac activity can be detected by transvaginal sonography (TVS) is:
Most accurate method to confirm viable intrauterine pregnancy at 6 weeks' gestation is
Which electrolyte imbalance causes prolonged QT interval?
Point-of-Care Cardiac Ultrasound Indian Medical PG Practice Questions and MCQs
Question 1: Pulse echo principle is used by which modality?
- A. X-ray
- B. CT
- C. MRI
- D. USG (Correct Answer)
Explanation: ***USG*** - **Ultrasound (USG)** imaging relies on the **pulse echo principle**, where high-frequency sound waves are emitted and their reflections (echoes) are detected to create images. - The transducer sends out a short **ultrasound pulse** and then listens for the echoes returning from structures within the body. *X-ray* - **X-ray** imaging uses **ionizing radiation** to produce images, where X-rays pass through the body and are absorbed differently by various tissues. - It does not involve emitting pulses or detecting echoes; instead, it measures the **attenuation of X-rays**. *CT* - **Computed Tomography (CT)** also uses **X-rays** but in a cross-sectional manner, rotating an X-ray source and detector around the patient. - It reconstructs detailed 3D images based on varying **X-ray absorption** and does not use sound waves or the pulse echo principle. *MRI* - **Magnetic Resonance Imaging (MRI)** utilizes strong **magnetic fields** and **radio waves** to produce detailed anatomical images. - It measures the signals emitted by **protons in water molecules** after they are excited by radiofrequency pulses, which is distinct from sound wave echoes.
Question 2: A patient presents with engorged neck veins, a blood pressure of 80/50 mmHg, and a pulse rate of 100 beats per minute following blunt trauma to the chest. The diagnosis is:
- A. Pneumothorax
- B. Right ventricular failure
- C. Cardiac tamponade (Correct Answer)
- D. Hemothorax
Explanation: ***Cardiac tamponade*** - The clinical presentation shows **two components of Beck's triad**: **engorged neck veins (elevated JVP)** and **hypotension** (80/50 mmHg). While muffled heart sounds (the third component) are not mentioned, this is not required for diagnosis. - The combination of **blunt chest trauma** and these symptoms strongly suggests fluid accumulation in the pericardial sac, compressing the heart and impairing its filling. - **Tachycardia** (100 bpm) represents a compensatory response to reduced cardiac output. *Pneumothorax* - While pneumothorax can cause respiratory distress and hypotension, it typically presents with **absent breath sounds** on the affected side and **hyperresonance to percussion**, which are not described. - Engorged neck veins are not characteristic of simple pneumothorax. **Tension pneumothorax** can cause distended neck veins and severe hypotension, but would also present with severe respiratory distress and tracheal deviation away from the affected side. *Right ventricular failure* - Right ventricular failure can cause **engorged neck veins** but usually presents with signs of systemic congestion like **peripheral edema** and hepatomegaly, developing over time. - This is not typically an acute, immediate consequence of blunt chest trauma. The **acute hypotension** and **tachycardia** are more indicative of obstructive shock (cardiac tamponade) rather than pump failure. *Hemothorax* - Hemothorax involves blood accumulation in the pleural space, leading to **absent breath sounds** and **dullness to percussion** on the affected side. - While it can cause hypotension and tachycardia due to **hypovolemic shock** from blood loss, **engorged neck veins** are not a feature. In fact, significant blood loss typically causes **flat or collapsed neck veins** due to reduced venous return.
Question 3: The imaging modality primarily used in FAST (Focused Assessment with Sonography for Trauma) exam is:
- A. X-ray
- B. CT
- C. MRI
- D. USG (Correct Answer)
Explanation: **USG** - **Focused Assessment with Sonography for Trauma (FAST)** exam specifically uses **ultrasound (USG)** to rapidly detect free fluid (blood) in pericardial, perihepatic, perisplenic, and pelvic spaces. - Its quick, non-invasive nature and portability make it ideal for **point-of-care assessment** in trauma settings. *X-ray* - While X-rays are useful in trauma for detecting **fractures** and some pneumothoraces, they are not the primary modality for detecting free fluid in the peritoneal or pericardial cavities during a FAST exam. - X-rays do not provide real-time, dynamic imaging of soft tissues and fluid accumulation as effectively as ultrasound. *CT* - **Computed Tomography (CT)** is a highly detailed imaging modality used in trauma for comprehensive assessment of injuries to organs, bones, and vessels. - However, it involves **radiation exposure**, takes longer to perform, and is typically reserved for hemodynamically stable patients after initial resuscitation and FAST exam. *MRI* - **Magnetic Resonance Imaging (MRI)** provides excellent soft tissue contrast, but its use in acute trauma is very limited due to its **long scan times**, high cost, and incompatibility with many metallic medical devices. - MRI is not suitable for rapid assessment of free fluid in hemodynamically unstable trauma patients.
Question 4: Which of the following does not form the left border of the heart?
- A. Pulmonary veins (Correct Answer)
- B. Left ventricle
- C. Aortic arch
- D. Pulmonary trunk
Explanation: **Pulmonary veins** - The pulmonary veins are positioned posteriorly and drain into the **left atrium**, thus they do not form part of the visible left cardiac border on a standard chest X-ray or during superficial anatomical viewing [1]. - The **left border of the heart** is primarily formed by the left ventricle, with contributions from the aortic arch and pulmonary trunk more superiorly [3]. *Left ventricle* - The **left ventricle** constitutes the major part of the left border of the heart, extending from the base to the apex [4]. - Its location and size make it a prominent feature on the left silhouette. *Aortic arch* - The **aortic arch** is located superior to the heart and gives rise to major systemic arteries [2]. - It forms a portion of the **upper left border** of the mediastinal silhouette, contributing to the cardiovascular outline. *Pulmonary trunk* - The **pulmonary trunk** arises from the right ventricle and branches into the pulmonary arteries [3]. - It contributes to the **upper left border** of the heart, medial to the aortic arch, as it courses superiorly before bifurcating.
Question 5: A young female presents with chest pain not associated with exercise. Auscultation reveals multiple ejection clicks with a murmur. The most important investigation for diagnosis is:
- A. ECG
- B. Thallium 201 scan
- C. Echocardiography (Correct Answer)
- D. Tc pyrophosphate scan
Explanation: ***Echocardiography*** - **Echocardiography** is the gold standard for visualizing cardiac structures and valve function, allowing direct assessment of **mitral valve prolapse (MVP)** [1]. - The presence of **multiple ejection clicks** and a murmur in a young female with non-exertional chest pain strongly suggests MVP, which can be confirmed by echocardiography [3]. *ECG* - An **ECG** can detect arrhythmias or signs of ischemia, but it cannot directly visualize the heart valves or diagnose **mitral valve prolapse** [2]. - While some MVP patients may have T-wave abnormalities or QT prolongation, these findings are non-specific and not diagnostic. *Thallium 201 scan* - A **Thallium 201 scan** is a nuclear imaging test primarily used to assess myocardial perfusion and detect areas of ischemia, usually in the context of **coronary artery disease** [4]. - It does not provide detailed anatomical information about heart valves or cardiac chamber morphology, making it unsuitable for diagnosing **mitral valve prolapse**. *Tc pyrophosphate scan* - A **Tc pyrophosphate scan** is primarily used to diagnose **amyloidosis** or evaluate myocardial infarction, particularly for detecting late-phase complications or right ventricular involvement. - It does not offer direct visualization of valvular structures and is not indicated for the diagnosis of **mitral valve prolapse**.
Question 6: Which among the following is the best method to assess adequacy of fluid resuscitation in a polytrauma patient:
- A. CVP
- B. Pulse rate
- C. Urine output (Correct Answer)
- D. BP
Explanation: ***Urine output*** - **Urine output** is a direct and real-time reflection of **renal perfusion**, which is highly sensitive to changes in circulating blood volume and cardiac output in trauma patients. - Maintaining a urine output of **0.5-1 mL/kg/hr** is generally accepted as a key indicator of adequate fluid resuscitation and organ perfusion in polytrauma. *CVP* - **Central Venous Pressure (CVP)** can be influenced by multiple factors beyond fluid status, such as **intrathoracic pressure**, **venous tone**, and **right ventricular function**, making it an unreliable sole indicator. - While it offers some insight into preload, CVP measurements alone do not provide a direct and dynamic assessment of **end-organ perfusion** in trauma. *Pulse rate* - **Pulse rate** is a non-specific indicator that can be affected by pain, anxiety, medications, and other systemic responses beyond fluid status in polytrauma. - While **tachycardia** often suggests hypovolemia, a normal pulse rate does not guarantee adequate fluid resuscitation, especially in patients with compensatory mechanisms. *BP* - **Blood pressure (BP)** is a relatively late indicator of hypovolemia in trauma, as compensatory mechanisms can maintain BP near normal despite significant blood loss. - Relying solely on BP can lead to delayed recognition of **inadequate resuscitation** and potential end-organ damage.
Question 7: Which chamber enlargement shows a double right heart border with a wide subcarinal angle?
- A. Left atrium (Correct Answer)
- B. Left ventricle
- C. Right atrium
- D. Right ventricle
Explanation: ***Left atrium*** - A **double right heart border** on a chest X-ray is a classic sign of **left atrial enlargement**, as the enlarged left atrium bulges into the right atrial silhouette. - The **wide subcarinal angle** (angle between the mainstem bronchi) also indicates left atrial enlargement, as the expanding left atrium pushes the bronchi apart. *Left ventricle* - **Left ventricular enlargement** primarily manifests as a **downward and leftward displacement of the apex** and increased cardiac silhouette on the left. - It does not typically cause a double right heart border or widening of the subcarinal angle. *Right atrium* - **Right atrial enlargement** usually presents as a **prominent right heart border** that extends further to the right than normal. - It does not result in a double right heart border or affect the subcarinal angle. *Right ventricle* - **Right ventricular enlargement** leads to an **anterior bowing of the sternum** (in severe cases) and an upward and leftward displacement of the cardiac apex. - It pushes the left ventricle posteriorly and does not produce a double right heart border or a wide subcarinal angle.
Question 8: The earliest crown-rump length (CRL) at which cardiac activity can be detected by transvaginal sonography (TVS) is:
- A. 1-4mm (Correct Answer)
- B. 1 cm
- C. 6-7mm
- D. 2-4 cm
Explanation: ***1-4mm*** - On **transvaginal ultrasonography (TVS)**, cardiac activity can typically be detected as early as **5-6 weeks of gestation** when the **crown-rump length (CRL)** is approximately **2-4mm**. - Cardiac activity is usually visible once the embryo reaches a **CRL of 5mm**, and a fetal pole with a CRL **≥5mm** without cardiac activity is suggestive of **embryonic demise** or **failed pregnancy**. - This represents the **earliest threshold** for reliable cardiac activity detection with modern high-resolution TVS. *1 cm* - A CRL of **1 cm (10 mm)** corresponds to approximately **7 weeks of gestation**. - By this size, cardiac activity should be clearly visible, making this far beyond the **earliest detection threshold**. - The absence of cardiac activity at this size would be diagnostic of **pregnancy failure**. *6-7mm* - While cardiac activity is reliably present at a CRL of **6-7mm** (around 6-6.5 weeks), this is not the **earliest** size at which it can be detected. - Modern TVS equipment can detect cardiac activity when the embryo is smaller, typically starting at **2-5mm CRL**. *2-4 cm* - A CRL of **2-4 cm (20-40 mm)** indicates **8.5 to 11 weeks of gestation**. - At this advanced stage, cardiac activity would be prominently visible, representing a much later developmental point than the **earliest detection threshold**.
Question 9: Most accurate method to confirm viable intrauterine pregnancy at 6 weeks' gestation is
- A. USG fetal cardiac activity (Correct Answer)
- B. Clinical examination
- C. Urine HCG test
- D. Doppler ultrasound in specific clinical situations
Explanation: **USG fetal cardiac activity** - At 6 weeks' gestation, the presence of **fetal cardiac activity** on ultrasound is the definitive sign of a **viable intrauterine pregnancy**. - This finding confirms both the presence of an embryo and its vital status, providing direct evidence of viability. *Urine HCG test* - A **urine HCG test** confirms the presence of pregnancy but does not provide information about its viability or location (intrauterine vs. ectopic). - High HCG levels can be present even in non-viable or ectopic pregnancies. *Clinical examination* - A **clinical examination** may reveal signs consistent with pregnancy, such as an enlarged uterus, but it cannot definitively confirm **intrauterine location** or **fetal viability** at 6 weeks' gestation. - These findings are supportive but not diagnostic of viability. *Doppler ultrasound in specific clinical situations* - Doppler ultrasound is typically used to assess **blood flow** to various structures and may be useful in later pregnancy for assessing fetal well-being or placental function. - It is not the primary or most accurate method to confirm early **fetal cardiac activity** or viability at 6 weeks' gestation compared to standard grayscale ultrasound.
Question 10: Which electrolyte imbalance causes prolonged QT interval?
- A. Hypocalcemia (Correct Answer)
- B. Hypernatremia
- C. Hyperkalemia
- D. Hyponatremia
Explanation: ***Hypocalcemia*** - **Hypocalcemia** prolongs the **QT interval** by delaying repolarization of ventricular myocytes, specifically by affecting the plateau phase of the action potential [2]. - Reduced extracellular **calcium** concentration decreases the activity of **L-type calcium channels**, extending the effective refractory period. *Hypernatremia* - **Hypernatremia** does not typically cause a prolonged QT interval; it primarily affects neuronal function and overall fluid balance. - While it can indirectly affect cardiac function through changes in cell excitability, it's not a direct cause of QT prolongation [1]. *Hyperkalemia* - **Hyperkalemia** primarily causes **peaked T waves**, a widened QRS complex, and a shortened QT interval or absence of P waves, rather than prolongation [1]. - Elevated extracellular **potassium** can accelerate repolarization, leading to a shortened QT interval [1]. *Hyponatremia* - **Hyponatremia** is more commonly associated with neurological symptoms like confusion and seizures due to cellular swelling, and it does not directly cause QT interval prolongation [1]. - While severe **hyponatremia** can affect myocardial function, it is not a classic cause of QT interval abnormalities.
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