Cardiology — MCQs

A 69-year-old man complains of chest tightness and shortness of breath after lifting boxes 3 hours ago. He perceives that his heart is skipping beats. His medical history is significant for hypertension and cigarette smoking. On examination, his heart rate is 50 beats/min and regular, and his lungs are clear to auscultation. An electrocardiogram shows bradycardia with an increased PR interval and ST-segment elevation in multiple leads including the anterior leads, V1 and V2. What anatomical structures are most likely affected?

Q164Medium

The murmur of hypertrophic obstructive cardiomyopathy is decreased in which of the following positions or maneuvers?

Q165Easy

Which of the following is true about the pain of pericarditis?

Q166Medium

What is the most common cause of native valve endocarditis?

Q167Medium

What are the ECG changes of hypomagnesemia?

Q168Easy

Takayasu's arteritis with pulmonary artery involvement is designated as which type?

Q169Medium

A 60-year-old man has had angina on exertion for the past 6 years. A coronary angiogram performed 2 years ago showed 75% stenosis of the left circumflex coronary artery and 50% stenosis of the right coronary artery. For the past 3 weeks, the frequency and severity of his anginal attacks have increased, and pain sometimes occurs even when he is lying in bed. On physical examination, his blood pressure is 110/80 mm Hg, and pulse is 85/min with irregular beats. An ECG shows ST-segment elevation. Laboratory studies show serum glucose, 188 mg/dL; creatinine, 1.2 mg/dL; and troponin I, 1.5 ng/mL. Which of the following is most likely to explain these findings?

Q170Medium

A 72-year-old male presents with intermittent symptoms of dyspnea on exertion, palpitations, and occasional blood-streaked cough. Cardiac auscultation reveals a faint, low-pitched diastolic rumbling murmur heard best at the apex. What is the most probable underlying cause of the patient's symptoms?

Cardiology Indian Medical PG Practice Questions and MCQs

Question 161: All of the following may occur due to hypokalemia, except?

A. Prolonged PR Interval
B. Prolonged QRS Interval (Correct Answer)
C. Prolonged QT Interval
D. Ventricular asystole

Explanation: Hypokalemia (Serum $K^+ < 3.5$ mEq/L) causes characteristic ECG changes primarily by delaying ventricular repolarization and increasing myocardial excitability. **Why "Prolonged QRS Interval" is the correct answer:** In hypokalemia, the QRS complex typically remains **normal in duration**, though it may show a slight increase in amplitude. Significant QRS widening is a hallmark of **Hyperkalemia** (due to slowed intraventricular conduction), not hypokalemia [1]. Therefore, this is the "except" option. **Analysis of other options:** * **Prolonged PR Interval:** Hypokalemia slows conduction through the AV node, which can lead to a prolonged PR interval and, in severe cases, AV blocks [1]. * **Prolonged QT Interval (Pseudo-prolongation):** This is a classic NEET-PG trap. Hypokalemia causes **T-wave flattening** and the appearance of prominent **U-waves**. As the T and U waves fuse, it creates the illusion of a prolonged QT interval, often referred to as a **prolonged QU interval**. * **Ventricular Asystole:** Severe hypokalemia increases the risk of life-threatening arrhythmias, including Ventricular Tachycardia, Torsades de Pointes, and eventually ventricular fibrillation or asystole. **High-Yield Clinical Pearls for NEET-PG:** 1. **Sequence of ECG changes in Hypokalemia:** T-wave flattening/inversion → ST-segment depression → Prominent U-waves (best seen in V2-V4) → Apparent QT prolongation (QU interval). 2. **Digoxin Toxicity:** Hypokalemia potentiates the effects of Digoxin, increasing the risk of arrhythmias even at "normal" therapeutic levels. 3. **Hyperkalemia Mnemonic:** "Tall T, Wide QRS, Flat P" (Tall peaked T-waves are the earliest sign) [1].

Question 162: Which medication should be administered to a patient with congestive heart failure and a left ventricular ejection fraction (LVEF) less than 40%?

A. ACE inhibitor + beta-blocker (Correct Answer)
B. ACE inhibitor + furosemide
C. ACE inhibitor + calcium channel blocker
D. ACE inhibitor + angiotensin II receptor blocker

Explanation: ### Explanation **Core Concept: Mortality Benefit in HFrEF** In patients with Heart Failure with reduced Ejection Fraction (HFrEF, LVEF <40%), the primary goal of pharmacological therapy is to block the maladaptive neurohormonal activation (Renin-Angiotensin-Aldosterone System and Sympathetic Nervous System) that leads to cardiac remodeling [1]. **ACE inhibitors (ACEIs)** and **Beta-blockers** are the foundational "disease-modifying" agents proven to reduce mortality and hospitalization in these patients [1], [2]. **Analysis of Options:** * **Option A (Correct):** ACEIs reduce afterload and prevent remodeling, while Beta-blockers (specifically Carvedilol, Metoprolol succinate, or Bisoprolol) prevent catecholamine-induced cardiotoxicity [2]. Together, they form the cornerstone of Guideline-Directed Medical Therapy (GDMT). * **Option B:** Furosemide (a loop diuretic) is excellent for symptomatic relief of congestion (edema/dyspnea) but has **no proven mortality benefit** [1]. * **Option C:** Non-dihydropyridine Calcium Channel Blockers (Verapamil/Diltiazem) are generally **avoided** in HFrEF due to their negative inotropic effects, which can worsen heart failure [3]. * **Option D:** Combining an ACEI and an ARB is generally avoided due to the increased risk of adverse effects like hyperkalemia and renal dysfunction without significant added survival benefit. **NEET-PG High-Yield Pearls:** 1. **The "Big Four" of HFrEF:** Current guidelines recommend a quadruple therapy to reduce mortality: **ARNI** (Sacubitril/Valsartan) or ACEI/ARB + **Beta-blocker** + **MRA** (Spironolactone) + **SGLT2 Inhibitor** (Dapagliflozin). 2. **Beta-blocker Initiation:** Never start a beta-blocker during an *acute* decompensation; the patient must be stable and "dry" (euvolemic). 3. **Contraindication:** ACEIs are strictly contraindicated in pregnancy and bilateral renal artery stenosis.

Question 163: A 69-year-old man complains of chest tightness and shortness of breath after lifting boxes 3 hours ago. He perceives that his heart is skipping beats. His medical history is significant for hypertension and cigarette smoking. On examination, his heart rate is 50 beats/min and regular, and his lungs are clear to auscultation. An electrocardiogram shows bradycardia with an increased PR interval and ST-segment elevation in multiple leads including the anterior leads, V1 and V2. What anatomical structures are most likely affected?

A. Left main coronary artery
B. Left anterior descending artery
C. Right coronary artery + Left anterior descending artery (Correct Answer)
D. Right coronary artery + Left circumflex artery

Explanation: ### Explanation The patient presents with an acute coronary syndrome (ACS) characterized by ST-segment elevation (STEMI) and significant bradyarrhythmia. The diagnosis depends on correlating the ECG findings with the coronary anatomy. **1. Why Option C is Correct:** * **LAD Involvement:** The ST-segment elevation in the **anterior leads (V1, V2)** is a classic hallmark of ischemia in the territory of the **Left Anterior Descending (LAD)** artery [1]. * **RCA Involvement:** The patient has **bradycardia (HR 50 bpm)** and an **increased PR interval** (1st-degree heart block). The Right Coronary Artery (RCA) supplies the Sinoatrial (SA) node in 60% of individuals and the Atrioventricular (AV) node in 90%. Bradyarrhythmias in the setting of an MI strongly suggest RCA occlusion affecting the conduction system. * **Combined Involvement:** The presence of both anterior STEMI and conduction disturbances indicates multivessel involvement or a variant anatomy where both territories are compromised. **2. Why Other Options are Incorrect:** * **Option A (LMCA):** Left Main occlusion typically presents with widespread ST-depression and ST-elevation in lead aVR. It usually causes cardiogenic shock rather than isolated bradycardia. * **Option B (LAD only):** While LAD explains the anterior ST elevation, it does not typically supply the SA or AV nodes [1]. Isolated LAD occlusion usually presents with tachycardia (sympathetic response) rather than bradycardia. * **Option D (RCA + LCx):** The LCx supplies the lateral wall (I, aVL, V5, V6). There is no mention of lateral lead changes, and LCx involvement does not explain the anterior (V1-V2) ST elevation. ### High-Yield Clinical Pearls for NEET-PG: * **Conduction System Supply:** * **AV Node:** RCA (90% - Right dominant), LCx (10% - Left dominant). * **SA Node:** RCA (60%), LCx (40%). * **Inferior MI (RCA):** Often associated with bradycardia and hypotension due to increased vagal tone (Bezold-Jarisch reflex) or nodal ischemia. * **Anterior MI (LAD):** Associated with the highest mortality and risk of heart failure; look for changes in V1-V4 [1].

Question 164: The murmur of hypertrophic obstructive cardiomyopathy is decreased in which of the following positions or maneuvers?

A. Supine position (Correct Answer)
B. Standing position
C. Valsalva maneuver
D. Amyl nitrite inhalation

Explanation: **Explanation:** The murmur of **Hypertrophic Obstructive Cardiomyopathy (HOCM)** is a harsh systolic ejection murmur [1] caused by dynamic left ventricular outflow tract (LVOT) obstruction. The intensity of this murmur depends on the **Left Ventricular (LV) volume**: * **Decreased LV Volume** (less blood) → Increases obstruction → **Louder murmur.** * **Increased LV Volume** (more blood) → Decreases obstruction → **Softer murmur.** **1. Why Supine Position is Correct:** When a patient moves from a standing to a **supine position**, there is an increase in venous return to the heart (increased preload). This increases the LV end-diastolic volume, which pushes the hypertrophied septum away from the mitral valve, widening the outflow tract and **decreasing the murmur intensity.** **2. Why the Other Options are Incorrect:** * **Standing Position:** Decreases venous return (preload), leading to a smaller LV cavity and an **increase** in murmur intensity. * **Valsalva Maneuver (Strain phase):** Increases intrathoracic pressure, which decreases venous return to the heart. This reduces LV volume and **increases** the murmur. * **Amyl Nitrite Inhalation:** This is a potent vasodilator that decreases systemic vascular resistance (afterload). Lower afterload facilitates faster ejection and smaller LV volume, thereby **increasing** the murmur. **Clinical Pearls for NEET-PG:** * **The "Rule of Two":** HOCM and Mitral Valve Prolapse (MVP) are the only two murmurs that get **louder** with standing and Valsalva. All other murmurs generally get softer. * **Handgrip Exercise:** Increases afterload, which pushes the septum away and **decreases** the HOCM murmur (unlike most other systolic murmurs). * **Squatting:** Increases both preload and afterload, significantly **decreasing** the HOCM murmur.

Question 165: Which of the following is true about the pain of pericarditis?

A. Pain increases on leaning forward
B. Pain decreases in supine position
C. Pain increases during inspiration (Correct Answer)
D. Pain increases on eating

Explanation: The correct answer is **C. Pain increases during inspiration.** ### **Explanation of the Correct Answer** The pain of acute pericarditis is typically **pleuritic** in nature. This occurs because the inflamed parietal pericardium is in close contact with the adjacent pleura. During inspiration, the lungs expand and the diaphragm moves downward, causing the inflamed layers to rub against each other or the pleura. This friction triggers sharp, stabbing pain [2]. Additionally, the phrenic nerve (which supplies the pericardium) can be irritated, often leading to pain radiation to the trapezius ridge [2]. ### **Analysis of Incorrect Options** * **A & B (Positional Changes):** Pericarditic pain is characteristically **positional**. It **decreases** (improves) when the patient leans forward (tripod position) because this pulls the heart away from the adjacent pleura and reduces tension on the pericardium. Conversely, the pain **increases** (worsens) in the **supine position** due to gravity-induced pressure on the parietal pericardium [2]. * **D (Eating):** Pain related to eating is more characteristic of gastrointestinal issues (like GERD or peptic ulcers). While swallowing (odynophagia) can occasionally aggravate pericarditis due to the esophagus's proximity to the posterior heart, it is not a classic diagnostic feature like pleuritic pain. ### **High-Yield Clinical Pearls for NEET-PG** * **ECG Findings:** Look for **diffuse ST-segment elevation** (concave upwards/saddle-shaped) and **PR-segment depression** (the most specific early sign) [1]. * **Physical Exam:** The pathognomonic sign is a **Pericardial Friction Rub**, best heard with the diaphragm at the left lower sternal border while the patient leans forward. * **Treatment:** First-line therapy includes **NSAIDs (High dose)** plus **Colchicine** (to prevent recurrence) [1]. Steroids are reserved for refractory cases or specific etiologies.

Question 166: What is the most common cause of native valve endocarditis?

A. Staphylococcus aureus (Correct Answer)
B. Coagulase-negative staphylococcus
C. Streptococcus
D. Enterococcus

Explanation: **Explanation:** The epidemiology of Infective Endocarditis (IE) has shifted significantly in recent decades. **Staphylococcus aureus** is now the most common cause of native valve endocarditis (NVE) worldwide, particularly in developed nations. This shift is attributed to the rise in healthcare-associated infections, intravenous drug use (IVDU), and the increased use of invasive procedures. *S. aureus* is highly virulent, capable of infecting healthy valves, and often leads to rapid valvular destruction and systemic embolization. **Analysis of Options:** * **Streptococcus (Option C):** Historically, *Streptococcus viridans* was the leading cause of NVE. While it remains a major cause (especially in patients with pre-existing valvular disease or poor dental hygiene), it has been surpassed by *S. aureus* in overall frequency. * **Coagulase-negative staphylococci (CoNS) (Option B):** These (e.g., *S. epidermidis*) are the most common cause of **Prosthetic Valve Endocarditis (PVE)**, particularly within the first year of surgery, but are less common in native valves. * **Enterococcus (Option D):** These are the third most common cause of IE, typically associated with older men undergoing genitourinary or gastrointestinal procedures. **High-Yield Clinical Pearls for NEET-PG:** * **IV Drug Users:** *S. aureus* is the most common cause, frequently involving the **Tricuspid valve**. * **Subacute IE:** Most commonly caused by *Streptococcus viridans*. * **Culture-Negative IE:** Most common cause is prior antibiotic therapy; otherwise, consider the **HACEK** group or *Coxiella burnetii*. * **Streptococcus bovis (S. gallolyticus):** If isolated, always perform a **colonoscopy** to rule out colorectal malignancy.

Question 167: What are the ECG changes of hypomagnesemia?

A. Decreased QT interval
B. Increased QT interval (Correct Answer)
C. Greatly increased PT interval
D. Tall T waves

Explanation: **Explanation:** Hypomagnesemia often coexists with other electrolyte imbalances (hypokalemia and hypocalcemia) and shares similar ECG features. The hallmark of hypomagnesemia is **prolongation of the QT interval**. This occurs because magnesium acts as a natural calcium channel blocker and cofactor for the Na+/K+-ATPase pump; its deficiency leads to delayed ventricular repolarization, thereby increasing the QT interval. This is clinically significant as it predisposes patients to **Torsades de Pointes**, a life-threatening polymorphic ventricular tachycardia [1]. **Analysis of Options:** * **A. Decreased QT interval:** This is incorrect. Shortening of the QT interval is typically seen in **hypercalcemia** and hypermagnesemia (though rare). * **B. Increased QT interval (Correct):** As explained, magnesium deficiency delays repolarization, lengthening the QT interval [1]. * **C. Greatly increased PT interval:** This is incorrect. The PT (Prothrombin Time) is a coagulation parameter, not an ECG finding. If referring to the **PR interval**, hypomagnesemia actually causes PR prolongation, but QT prolongation is the more classic association. * **D. Tall T waves:** This is incorrect. Tall, peaked T waves are the classic sign of **hyperkalemia**. In hypomagnesemia, T waves are more likely to be flattened or inverted. **High-Yield NEET-PG Pearls:** 1. **The "Magnesium-Potassium" Link:** Refractory hypokalemia cannot be corrected until hypomagnesemia is treated first. 2. **ECG Summary:** Look for prolonged QT, PR prolongation, ST-segment depression, and T-wave flattening/inversion. 3. **Drug of Choice:** Intravenous Magnesium Sulfate is the treatment of choice for Torsades de Pointes, even if serum magnesium levels are normal [1].

Question 168: Takayasu's arteritis with pulmonary artery involvement is designated as which type?

A. Type I
B. Type II
C. Type III
D. Type IV (Correct Answer)

Explanation: **Explanation:** Takayasu’s Arteritis (Pulseless Disease) is a chronic inflammatory large-vessel vasculitis that primarily affects the aorta and its main branches [1]. The classification of Takayasu’s arteritis is based on the anatomical distribution of the lesions as defined by the **Numano Classification (1996)**: * **Type IV (Correct Answer):** This type specifically involves the **Pulmonary Artery**. It can occur in isolation or in combination with any of the other types (e.g., Type IV+). Pulmonary involvement can lead to pulmonary hypertension and is a critical prognostic factor. **Analysis of Incorrect Options:** * **Type I:** Involves only the branches of the **Aortic Arch** (e.g., carotid, subclavian arteries). * **Type II:** Involves the **Ascending Aorta, Aortic Arch, and its branches** (Type IIa) or extends to include the **Thoracic Descending Aorta** (Type IIb). * **Type III:** Involves the **Thoracic Descending Aorta, Abdominal Aorta, and/or Renal Arteries**. The aortic arch is spared. * **Type V:** A generalized form combining features of Type IIb and Type III (involvement of the entire aorta and its branches). **High-Yield Clinical Pearls for NEET-PG:** * **Demographics:** Most common in young females (<40 years) of Asian descent. * **Clinical Feature:** Discrepancy in blood pressure between arms and absent/feeble peripheral pulses. * **Diagnosis:** Magnetic Resonance Angiography (MRA) or CT Angiography is the gold standard for visualizing vessel wall thickening and narrowing [1]. * **Pathology:** Characterized by "skip lesions" and granulomatous inflammation of the adventitia and media. * **Treatment:** Glucocorticoids are the first-line treatment.

Question 169: A 60-year-old man has had angina on exertion for the past 6 years. A coronary angiogram performed 2 years ago showed 75% stenosis of the left circumflex coronary artery and 50% stenosis of the right coronary artery. For the past 3 weeks, the frequency and severity of his anginal attacks have increased, and pain sometimes occurs even when he is lying in bed. On physical examination, his blood pressure is 110/80 mm Hg, and pulse is 85/min with irregular beats. An ECG shows ST-segment elevation. Laboratory studies show serum glucose, 188 mg/dL; creatinine, 1.2 mg/dL; and troponin I, 1.5 ng/mL. Which of the following is most likely to explain these findings?

A. Atheromatous plaque fissure with thrombosis (Correct Answer)
B. Constrictive pericarditis with calcification
C. Endomyocardial fibrosis
D. Extensive myocardial fiber hypertrophy

Explanation: The patient is presenting with **Acute Coronary Syndrome (ACS)**, specifically a **ST-Elevation Myocardial Infarction (STEMI)** [3]. The clinical progression from stable angina (6 years) to crescendo angina (increased frequency/severity) and pain at rest (decubitus angina) indicates unstable plaque dynamics [1]. The elevated Troponin I (1.5 ng/mL) confirms myocardial necrosis [3]. **1. Why Option A is Correct:** The fundamental pathophysiology of ACS (Unstable Angina, NSTEMI, and STEMI) is the **disruption of an unstable atheromatous plaque**. A fissure or rupture in the fibrous cap exposes the underlying necrotic core and collagen to circulating platelets, leading to **thrombosis** [3]. In this case, the ST-segment elevation suggests a complete, transmural occlusion of the coronary artery by a thrombus, typically occurring at the site of a pre-existing but not necessarily critical stenosis [2]. **2. Why Incorrect Options are Wrong:** * **Option B (Constrictive Pericarditis):** Presents with signs of right heart failure (JVP elevation, Kussmaul sign) and a "pericardial knock," not acute ST-elevation or troponin rise. * **Option C (Endomyocardial Fibrosis):** A restrictive cardiomyopathy common in tropical regions; it causes heart failure symptoms but does not explain acute ECG changes or ischemic pain. * **Option D (Myocardial Fiber Hypertrophy):** While it can cause secondary ischemia due to increased demand (e.g., in HOCM or Hypertension), it does not typically present with acute plaque-related ST-elevation and elevated troponins in this clinical context [4]. **Clinical Pearls for NEET-PG:** * **Stable Angina:** Fixed stenosis (usually >70%), pain on exertion, relieved by rest [1]. * **Unstable Angina/NSTEMI:** Plaque rupture with *subtotal* occlusion [1]. * **STEMI:** Plaque rupture with *total* occlusion [1][3]. * **High-Yield:** The most common site of plaque rupture is often a lesion that was previously <50% stenosed on angiography, as these "soft" plaques have thinner fibrous caps.

Question 170: A 72-year-old male presents with intermittent symptoms of dyspnea on exertion, palpitations, and occasional blood-streaked cough. Cardiac auscultation reveals a faint, low-pitched diastolic rumbling murmur heard best at the apex. What is the most probable underlying cause of the patient's symptoms?

A. Rheumatic fever during youth (Correct Answer)
B. Long-standing hypertension
C. Silent myocardial infarction within the past year
D. Congenital cardiac anomaly

Explanation: ### Explanation **Correct Answer: A. Rheumatic fever during youth** The clinical presentation is classic for **Mitral Stenosis (MS)**. The "faint, low-pitched diastolic rumbling murmur heard best at the apex" is the hallmark of MS [1][4]. The patient’s symptoms—dyspnea on exertion (due to pulmonary venous hypertension), palpitations (likely secondary to atrial fibrillation from left atrial enlargement), and hemoptysis (rupture of bronchial veins)—further support this diagnosis [1][5]. In adults, the **most common cause of Mitral Stenosis is Rheumatic Heart Disease (RHD)**, resulting from an autoimmune response to Group A Streptococcal pharyngitis during childhood [2]. Even if the patient does not recall an acute episode, the latent period between rheumatic fever and symptomatic valve stenosis is typically 20–40 years [3]. **Why Incorrect Options are Wrong:** * **B. Long-standing hypertension:** Typically leads to Left Ventricular Hypertrophy (LVH) or heart failure with preserved ejection fraction. It may cause an S4 gallop or a systolic murmur of functional mitral regurgitation, but not a diastolic rumble. * **C. Silent MI:** Usually results in ischemic mitral regurgitation (systolic murmur) due to papillary muscle dysfunction or ventricular remodeling, not stenosis. * **D. Congenital cardiac anomaly:** While congenital MS (e.g., Parachute Mitral Valve) exists, it is extremely rare and usually presents in infancy or childhood, not at age 72. **NEET-PG High-Yield Pearls:** * **Auscultation:** MS is characterized by a loud S1, an Opening Snap (OS), and a mid-diastolic rumbling murmur [1]. * **Severity Marker:** The shorter the **S2-OS interval**, the more severe the stenosis. * **Ortner’s Syndrome:** Hoarseness of voice due to left recurrent laryngeal nerve compression by a giant left atrium (a known complication of MS). * **ECG Finding:** "P mitrale" (broad, notched P waves in Lead II) indicating left atrial enlargement.

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Cardiology — MCQs

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