Cardiovascular US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Cardiovascular. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Cardiovascular US Medical PG Question 1: A 58-year-old man comes to the emergency department for complaints of crushing chest pain for 4 hours. He was shoveling snow outside when the pain started. It is rated 7/10 and radiates to his left arm. An electrocardiogram (ECG) demonstrates ST-segment elevation in leads V2-4. He subsequently undergoes percutaneous coronary intervention (PCI) and is discharged with aspirin, clopidogrel, carvedilol, atorvastatin, and lisinopril. Five days later, the patient is brought to the emergency department by his wife with complaints of dizziness. He reports lightheadedness and palpitations for the past 2 hours but otherwise feels fine. His temperature is 99.7°F (37.6°C), blood pressure is 95/55 mmHg, pulse is 105/min, and respirations are 17/min. A pulmonary artery catheter is performed and demonstrates an increase in oxygen concentration at the pulmonary artery. What finding would you expect in this patient?
- A. Widespread ST-segment elevations
- B. Harsh, loud, holosystolic murmur at the lower left sternal border (Correct Answer)
- C. Pulseless electrical activity
- D. Drop of systolic blood pressure by 20 mmHg during inspiration
- E. Normal findings
Cardiovascular Explanation: ***Harsh, loud, holosystolic murmur at the lower left sternal border***
- This patient's presentation, including recent **anterior STEMI**, dizziness, lightheadedness, palpitations, hypotension, tachycardia, and **increased oxygen saturation in the pulmonary artery** (oxygen "step-up" indicating a left-to-right shunt), is highly suggestive of **ventricular septal rupture (VSR)**.
- VSR is a **mechanical complication** of MI that typically occurs **3-7 days post-infarction** when the necrotic myocardium is weakest.
- A **VSR** causes a **harsh, loud, holosystolic murmur** best heard at the **lower left sternal border** due to turbulent blood flow through the septal defect from the left ventricle to the right ventricle.
- The left-to-right shunt results in oxygenated blood from the left ventricle mixing with deoxygenated blood in the right ventricle, causing the characteristic oxygen saturation step-up detected by pulmonary artery catheterization.
*Widespread ST-segment elevations*
- Widespread ST-segment elevations are characteristic of **acute pericarditis**, which typically presents with **pleuritic chest pain** that improves when leaning forward and a **friction rub**, not the hemodynamic compromise described here.
- While **Dressler syndrome** (post-MI pericarditis) can occur weeks after MI, the acute hemodynamic instability, left-to-right shunt evidence, and 5-day timeframe point to VSR rather than pericarditis.
*Pulseless electrical activity*
- **Pulseless electrical activity (PEA)** indicates cardiac arrest with organized electrical activity but no mechanical cardiac output, resulting in an **unpalpable pulse**.
- The patient has a documented pulse of **105/min**, which directly contradicts PEA.
- A patient in PEA would be unconscious and unable to report symptoms for 2 hours.
*Drop of systolic blood pressure by 20 mmHg during inspiration*
- A drop in systolic blood pressure >10 mmHg during inspiration (**pulsus paradoxus**) is characteristic of **cardiac tamponade** or severe obstructive airway disease.
- While **free wall rupture** leading to tamponade is another mechanical complication post-MI, the **oxygen saturation step-up** in the pulmonary artery is pathognomonic for an **intracardiac shunt** (VSR), not tamponade.
- Tamponade would show equalization of diastolic pressures across all chambers, not increased PA oxygen saturation.
*Normal findings*
- The patient presents with clear evidence of hemodynamic compromise: **hypotension (95/55 mmHg)**, **tachycardia (105/min)**, dizziness, and lightheadedness.
- The **oxygen saturation step-up** in the pulmonary artery is an objective abnormal finding indicating an intracardiac left-to-right shunt.
- Therefore, normal findings are incompatible with this clinical presentation.
Cardiovascular US Medical PG Question 2: A 67-year-old man comes to the emergency department because of retrosternal chest pressure and shortness of breath for 4 hours. The symptoms started while he was walking to work and have only minimally improved with rest. He has a history of type 2 diabetes mellitus. He has smoked one pack of cigarettes daily for 35 years. He appears uncomfortable. His pulse is 95/min. Serum studies show a normal troponin concentration. An ECG shows no abnormalities. Which of the following is the most likely underlying cause of this patient's symptoms?
- A. Atherosclerotic plaque thrombus with complete coronary artery occlusion
- B. Stable atherosclerotic plaque with 85% coronary artery occlusion
- C. Aortic valve thickening and calcification
- D. Disruption of an atherosclerotic plaque with a non-occlusive coronary artery thrombus (Correct Answer)
- E. Coronary artery occlusion due to transient increase in vascular tone
Cardiovascular Explanation: **Disruption of an atherosclerotic plaque with a non-occlusive coronary artery thrombus**
- This scenario describes **unstable angina (UA)**, characterized by chest pain at rest or with minimal exertion, increased frequency/intensity of angina, or new-onset severe angina.
- While troponin is normal and ECG shows no abnormalities, the persistent symptoms and minimal improvement with rest, along with risk factors like **diabetes** and **smoking**, strongly suggest an **unstable coronary lesion** that is not yet fully occlusive.
*Atherosclerotic plaque thrombus with complete coronary artery occlusion*
- **Complete coronary artery occlusion** typically leads to myocardial infarction (MI), which would manifest with **elevated troponin levels** and often **ECG changes** (e.g., ST elevation or depression).
- The patient's normal troponin and ECG rule out an acute MI at this stage.
*Stable atherosclerotic plaque with 85% coronary artery occlusion*
- **Stable angina** symptoms usually improve promptly with rest and are predictable, occurring only during significant exertion.
- The described symptoms, including minimal improvement with rest and 4 hours duration, are not typical of stable angina.
*Aortic valve thickening and calcification*
- While **aortic stenosis** can cause chest pain and shortness of breath, these symptoms are typically exertional and not usually described as "retrosternal pressure" that minimally improves with rest in this acute context without other signs of flow obstruction.
- This condition is unlikely to be the sole cause of these acute, persistent symptoms without findings on initial workup.
*Coronary artery occlusion due to transient increase in vascular tone*
- **Coronary vasospasm** (Prinzmetal angina) can cause chest pain at rest and transient ECG changes, but it's typically **recurrent** and responds well to **vasodilators**.
- This patient's symptoms, combined with risk factors for atherosclerosis and the prolonged nature of the pain, are less indicative of vasospasm as the primary underlying cause.
Cardiovascular US Medical PG Question 3: A medical research study is evaluating an investigational novel drug (medication 1) as compared with standard therapy (medication 2) in patients presenting to the emergency department with myocardial infarction (MI). The study enrolled a total of 3,000 subjects, 1,500 in each study arm. Follow-up was conducted at 45 days post-MI. The following are the results of the trial:
Endpoints Medication 1 Medication 2 P-Value
Primary: death from cardiac causes 134 210 0.03
Secondary: hyperkalemia 57 70 0.4
What is the relative risk of death from a cardiac cause, expressed as a percentage? (Round to the nearest whole number.)
- A. 64% (Correct Answer)
- B. 42%
- C. 72%
- D. 36%
- E. 57%
Cardiovascular Explanation: ***64%***
- The **relative risk (RR)** is calculated as the event rate in the exposed group divided by the event rate in the unexposed (control) group.
- For cardiac death, the event rate for Medication 1 is 134/1500 = 0.0893, and for Medication 2 is 210/1500 = 0.14. Therefore, RR = 0.0893 / 0.14 = 0.6378.
- Expressing as a percentage: 0.6378 × 100 = 63.78%, which rounds to **64%**.
- This indicates that Medication 1 has 64% of the risk of cardiac death compared to Medication 2, representing a **36% relative risk reduction**.
*42%*
- This option is incorrect as it does not reflect the accurate calculation of **relative risk** using the provided event rates.
- A calculation error or conceptual misunderstanding of the relative risk formula would lead to this value.
*72%*
- This percentage is higher than the calculated relative risk, suggesting an incorrect application of the formula or a misinterpretation of the event rates.
- It does not represent the ratio of risk between the two medication groups for cardiac death.
*36%*
- This value represents the **relative risk reduction** (100% - 64% = 36%), not the relative risk itself.
- This is a common error where students confuse relative risk with relative risk reduction.
*57%*
- While closer to the correct answer, this value is not the precise result when rounding to the nearest whole number.
- Small calculation discrepancies or rounding at intermediate steps could lead to this slightly different percentage.
Cardiovascular US Medical PG Question 4: Cardiac muscle serves many necessary functions, leading to a specific structure that serves these functions. The structure highlighted is an important histology component of cardiac muscle. What would be the outcome if this structure diffusely failed to function?
- A. Failure of potassium channels to appropriately open to repolarize the cell
- B. Failure of propagation of the action potential from the conduction system (Correct Answer)
- C. Ineffective excitation-contraction coupling due to insufficient calcium ions
- D. Inappropriate formation of cardiac valve leaflets
- E. Outflow tract obstruction
Cardiovascular Explanation: ***Failure of propagation of the action potential from the conduction system***
- The highlighted structure, the **intercalated disc**, contains **gap junctions** which are crucial for the rapid, synchronized spread of **action potentials** between cardiac muscle cells.
- A diffuse failure of these structures would prevent the coordinated electrical activation of the myocardium, leading to a failure of impulse propagation and **compromised cardiac contraction**.
*Failure of potassium channels to appropriately open to repolarize the cell*
- This scenario describes a problem with **ion channel function** within individual cardiomyocytes, affecting their repolarization phase.
- While critical for a single cell's electrical activity, it does not directly relate to the primary function of **intercalated discs** in *propagating* action potentials across multiple cells.
*Ineffective excitation-contraction coupling due to insufficient calcium ions*
- This outcome would result from issues with **calcium handling** mechanisms, such as problems with the **sarcoplasmic reticulum** or **calcium channels**, which are internal to the cardiomyocyte.
- It is distinct from the role of **intercalated discs** in facilitating intercellular communication and electrical spread.
*Inappropriate formation of cardiac valve leaflets*
- The formation of cardiac valve leaflets is an intricate process during **embryological development** involving specific signaling pathways and cell migration.
- This structural defect is not directly related to the function of **intercalated discs** in mature cardiac muscle, which are involved in electrical and mechanical coupling.
*Outflow tract obstruction*
- **Outflow tract obstruction** is a congenital or acquired structural defect affecting the major arteries leaving the heart (e.g., aortic or pulmonary stenosis).
- This is a macroscopic structural anomaly that is not caused by a primary failure of **intercalated disc** function.
Cardiovascular US Medical PG Question 5: A 55-year-old man comes to the physician because of a 4-month history of episodic, pressure-like chest pain. The chest pain occurs when he is walking up stairs and improves with rest. He has hypertension and type 2 diabetes mellitus. His father died from a myocardial infarction at the age of 50 years. Current medications include hydrochlorothiazide and metformin. His pulse is 85/min, respirations are 12/min, and blood pressure is 140/90 mm Hg. Cardiac examination shows normal heart sounds without any murmurs, rubs, or gallops. An ECG shows high amplitude of the S wave in lead V3. An exercise stress test is performed but stopped after 4 minutes because the patient experiences chest pain. An ECG obtained during the stress test shows sinus tachycardia and ST-segment depressions in leads V1–V4. Which of the following is the most appropriate long-term pharmacotherapy to reduce the frequency of symptoms in this patient?
- A. Metoprolol (Correct Answer)
- B. Clopidogrel
- C. Aspirin
- D. Nitroglycerin
- E. Isosorbide mononitrate
Cardiovascular Explanation: ***Metoprolol***
- **Beta-blockers** like metoprolol are first-line agents for **symptom relief** in stable angina by reducing myocardial oxygen demand.
- They decrease **heart rate**, **blood pressure**, and **myocardial contractility**, thereby reducing the frequency and severity of anginal episodes.
*Clopidogrel*
- **Clopidogrel** is an antiplatelet agent used primarily to prevent **thrombotic events** in patients with established cardiovascular disease or acute coronary syndromes.
- It does not directly reduce the frequency of anginal symptoms, but rather prevents progression to **myocardial infarction** or **stroke**.
*Aspirin*
- **Aspirin** is an antiplatelet medication used for **secondary prevention** of cardiovascular events by inhibiting platelet aggregation.
- While crucial for reducing cardiovascular risk, it does not directly alleviate the **frequency of anginal symptoms** themselves.
*Nitroglycerin*
- **Nitroglycerin** is a short-acting nitrate used to provide **immediate relief** of anginal pain during an acute episode.
- It is not a long-term pharmacotherapy for reducing the *frequency* of symptoms.
*Isosorbide mononitrate*
- **Isosorbide mononitrate** is a long-acting nitrate used to *prevent* angina, but it is typically a **second-line agent** after beta-blockers due to potential for **tolerance** and side effects.
- While it can reduce symptom frequency, beta-blockers are generally preferred as initial long-term therapy for symptom control.
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