Cardiac Pathology — MCQs

A 25-year-old man suffers a sudden cardiac arrest and is resuscitated. His vital signs are normal on examination. Echocardiography reveals a normal left ventricle but marked thinning and dilation of the right ventricle. MRI of his chest shows extensive fibrofatty replacement of the myocardium without inflammation. What is the most likely cause for these findings?

Q124Medium

In which of the following conditions are vegetations friable and easily detachable from the cardiac valves?

Q125Easy

When do neutrophils appear in myocardial infarction?

Q126Medium

All of the following are true regarding marantic endocarditis except?

Q127Easy

McCallum's patch is diagnostic of which condition?

Q128Medium

Which of the following is true about Libman-Sacks endocarditis?

Q129Easy

Which of the following does NOT cause coronary occlusion?

Q130Medium

All the statements regarding atherosclerosis are true, except:

Cardiac Pathology Indian Medical PG Practice Questions and MCQs

Question 121: What is the most common site of myocardial infarction?

A. Anterior wall of left ventricle (Correct Answer)
B. Posterior wall of left ventricle
C. Posterior wall of right ventricle
D. Inferior wall of left ventricle

Explanation: **Explanation:** The location of a myocardial infarction (MI) is determined by the specific coronary artery that is occluded. The **Left Anterior Descending (LAD) artery** is the most frequently involved vessel in coronary atherosclerosis, often referred to as the "widow-maker." 1. **Why Option A is Correct:** The LAD artery supplies the **anterior wall of the left ventricle**, the anterior 2/3rd of the interventricular septum, and the cardiac apex [1]. Because the LAD is the most common site of thrombotic occlusion (40–50% of cases), the **Anterior wall of the left ventricle** is the most common site of infarction [1]. 2. **Why Other Options are Incorrect:** * **Option B & D:** The posterior and inferior walls of the left ventricle are typically supplied by the **Right Coronary Artery (RCA)** [1]. RCA occlusion occurs in approximately 30–40% of cases, making it the second most common site. * **Option C:** Isolated Right Ventricular (RV) infarcts are rare because the RV has a lower oxygen demand and better collateral flow. RV involvement usually occurs as an extension of an inferior wall LV infarct. **NEET-PG High-Yield Pearls:** * **Frequency of Occlusion:** LAD (40-50%) > RCA (30-40%) > Left Circumflex (LCX) (15-20%) [1]. * **LCX Infarction:** Leads to lateral wall ischemia/infarction. * **ECG Correlation:** Anterior wall MI shows ST-elevation in leads **V1–V4**. * **Complication:** Anterior wall infarcts are more likely to lead to free wall rupture, ventricular aneurysms, and cardiogenic shock compared to other sites [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 550-552. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 288-289.

Question 122: A 10-year-old boy died of acute rheumatic fever. All of the following can be expected at autopsy EXCEPT:

A. Ashoff nodules
B. Rupture of chordae tendinae (Correct Answer)
C. McCallum patch
D. Fibrinous pericarditis

Explanation: ### Explanation The correct answer is **B. Rupture of chordae tendinae**. **1. Why Rupture of Chordae Tendinae is the Correct Answer:** Acute Rheumatic Fever (ARF) is characterized by **pancarditis** (inflammation of all three layers of the heart). While the chordae tendinae do become thickened, edematous, and fused during the chronic phase of Rheumatic Heart Disease (RHD), they **do not typically rupture** during the acute phase [1]. Rupture of chordae tendinae is a classic complication of **Infective Endocarditis (IE)** [1] or **Acute Myocardial Infarction**, not ARF. **2. Analysis of Incorrect Options:** * **A. Aschoff Nodules:** These are the pathognomonic histological hallmark of ARF [1]. They are granulomatous foci consisting of T-cells, plasma cells, and characteristic **Anitschkow cells** (caterpillar cells) [1]. * **C. MacCallum Patch:** This refers to subendocardial thickening, usually in the **posterior wall of the left atrium**, caused by the inflammatory effect of regurgitant jets (mitral regurgitation) during the acute phase. * **D. Fibrinous Pericarditis:** The pericardial involvement in ARF typically manifests as a "Bread and Butter" appearance due to fibrinous exudate [2]. **3. High-Yield NEET-PG Pearls:** * **Pathognomonic cell:** Anitschkow cell (enlarged macrophages with "caterpillar" chromatin) [1]. * **Most common valve involved:** Mitral valve (followed by Aortic). * **Chronic RHD:** Characterized by "Fish-mouth" or "Button-hole" stenosis due to commissural fusion [1]. * **Jones Criteria:** Used for clinical diagnosis (Major: Joint, Carditis, Nodules, Erythema marginatum, Sydenham chorea). * **Key Distinction:** ARF causes **verrucae** (small, sterile vegetations) along the lines of closure [1]; IE causes large, friable vegetations that lead to structural destruction like chordal rupture [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 566-568. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 581-582.

Question 123: A 25-year-old man suffers a sudden cardiac arrest and is resuscitated. His vital signs are normal on examination. Echocardiography reveals a normal left ventricle but marked thinning and dilation of the right ventricle. MRI of his chest shows extensive fibrofatty replacement of the myocardium without inflammation. What is the most likely cause for these findings?

A. Arrhythmogenic right ventricular cardiomyopathy (Correct Answer)
B. Chagas disease
C. Hypertension
D. Long QT syndrome

Explanation: ### Explanation **Correct Answer: A. Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)** **Why it is correct:** ARVC is an autosomal dominant inherited heart muscle disease characterized by the **replacement of the right ventricular (RV) myocardium with fibrofatty tissue** [1]. This occurs due to mutations in genes encoding **desmosomal proteins** (e.g., Plakoglobin, Desmoplakin), leading to cell-to-cell detachment and subsequent myocyte death [1]. * **Clinical Presentation:** It typically presents in young adults with palpitations, syncope, or **sudden cardiac arrest** due to ventricular arrhythmias (VT/VF) [1]. * **Imaging:** MRI is the gold standard, showing RV dilation, wall thinning, and characteristic fatty infiltration [1]. The absence of inflammation distinguishes it from myocarditis. **Why the other options are incorrect:** * **B. Chagas Disease:** Caused by *Trypanosoma cruzi*, it typically presents with apical aneurysms, biventricular failure, and megaesophagus/megacolon. Histology would show chronic inflammation and parasites, not isolated fibrofatty replacement. * **C. Hypertension:** This leads to **Left Ventricular Hypertrophy (LVH)** and concentric thickening, not RV thinning or fibrofatty replacement. * **D. Long QT Syndrome:** This is a channelopathy (electrical disorder) involving ion channels (K+ or Na+). While it causes sudden cardiac arrest, the heart structure remains **grossly and histologically normal**. **High-Yield Pearls for NEET-PG:** * **Naxos Disease:** A specific variant of ARVC associated with **woolly hair** and **palmoplantar keratoderma** (mutation in *Plakoglobin*) [1]. * **Triangle of Dysplasia:** The areas most affected in ARVC are the RV inflow, outflow, and apex. * **ECG Finding:** Look for an **Epsilon wave** (a small notch at the end of the QRS complex) in leads V1-V3. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 576-577.

Question 124: In which of the following conditions are vegetations friable and easily detachable from the cardiac valves?

A. Rheumatic fever
B. Rheumatoid heart disease
C. Systemic lupus erythematosus (SLE)
D. Infective endocarditis (Correct Answer)

Explanation: **Explanation:** The correct answer is **Infective Endocarditis (IE)**. The nature of cardiac vegetations is a high-yield topic in pathology, often distinguished by their size, location, and adherence. **1. Why Infective Endocarditis is correct:** In IE, vegetations consist of a bulky mass of platelets, fibrin, and **microorganisms** (bacteria or fungi). Because these organisms actively destroy the underlying valvular tissue (necrosis), the attachment is weak. Consequently, the vegetations are **large, friable (easily crumbled), and easily detachable**, leading to a high risk of systemic embolization and septic infarcts [1]. **2. Why the other options are incorrect:** * **Rheumatic Fever:** Vegetations (verrucae) are **small (1-2 mm), firm, and sterile**. They are arranged in a row along the lines of closure and are firmly adherent, rarely embolizing [1]. * **Rheumatoid Heart Disease:** Similar to rheumatic fever, these involve small, firm granulomatous nodules that do not typically detach. * **Systemic Lupus Erythematosus (Libman-Sacks Endocarditis):** These vegetations are small to medium-sized and sterile. Their hallmark is that they can occur on **both sides of the valve leaflets** (undersurfaces and chordae), but they are generally more adherent than those in IE [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Most common valve involved:** Mitral valve (except in IV drug users, where it is the **Tricuspid valve**) [2]. * **Non-Bacterial Thrombotic Endocarditis (NBTE):** Also features friable vegetations, but they are sterile and typically associated with **marantic endocarditis** or underlying malignancy (Trousseau sign) [1]. * **Mnemonic for IE Vegetations:** "Large, Friable, Destructive." * **Location:** IE vegetations usually occur on the **atrial surface** of AV valves and the **ventricular surface** of semilunar valves. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 568-570. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 295-296.

Question 125: When do neutrophils appear in myocardial infarction?

A. Less than 4 hours
B. 4-12 hours
C. 12-24 hours (Correct Answer)
D. 1-3 days

Explanation: ### Explanation The timeline of histological changes in Myocardial Infarction (MI) is a high-yield topic for NEET-PG. The correct answer is **12-24 hours**. **1. Why 12-24 hours is correct:** During the first 12-24 hours, the primary histological change is **coagulative necrosis**. As cells die, they release chemotactic factors (complement fragments like C5a and cytokines) [2]. This initiates the acute inflammatory response, leading to the **first appearance of neutrophils** at the periphery of the infarct [1]. Grossly, the heart may show dark mottling [1]. **2. Analysis of Incorrect Options:** * **Less than 4 hours:** No gross or light microscopic changes are visible [1]. Only electron microscopy might show mitochondrial swelling or sarcolemmal disruption [1]. * **4-12 hours:** Early changes like **"wavy fibers"** (due to stretching of non-contractile dead fibers) and early coagulative necrosis begin [1], but the inflammatory infiltrate (neutrophils) is not yet prominent. * **1-3 days:** This is the period of **peak neutrophil infiltration** [1]. While neutrophils *appear* at 12-24 hours, they are most abundant and widespread during this window, accompanied by total loss of nuclei and striations [1]. **3. Clinical Pearls for NEET-PG:** * **Golden Rule of Inflammation:** Neutrophils are the hallmark of acute inflammation (1-3 days), while **Macrophages** take over at **3-7 days** to clear debris [1]. * **Granulation Tissue:** Appears at **7-10 days** (most prominent at the borders). * **Scar Formation:** Type I collagen deposition (scarring) begins after 2 weeks and is usually complete by **2 months**. * **CK-MB vs. Troponin:** Troponins rise within 3-12 hours and stay elevated for days, whereas CK-MB returns to baseline in 48-72 hours (useful for detecting re-infarction). **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 552. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 87-89.

Question 126: All of the following are true regarding marantic endocarditis except?

A. Vegetation may embolize
B. Vegetations along the line of closure of leaflets
C. Affects damaged valves (Correct Answer)
D. May be associated with hypercoagulable states

Explanation: Explanation: Marantic endocarditis, also known as **Non-Bacterial Thrombotic Endocarditis (NBTE)**, is characterized by the deposition of small, sterile thrombi (fibrin and platelets) on cardiac valves. **Why Option C is the correct answer (The Exception):** Unlike Subacute Bacterial Endocarditis (SBE), which typically occurs on previously damaged or deformed valves, NBTE characteristically occurs on **previously normal valves**. The pathogenesis is not related to structural valve disease or infection, but rather to systemic hypercoagulability or endothelial trauma [1]. **Analysis of other options:** * **Option A:** The vegetations in NBTE are **friable** and loosely attached because there is no significant underlying inflammation or organization. Therefore, they frequently break off and **embolize** to the brain, kidneys, or spleen. * **Option B:** Similar to Rheumatic Heart Disease, the vegetations in NBTE are typically small (1–5 mm) and occur **along the line of closure** of the valve leaflets (most commonly the mitral valve) [1]. * **Option D:** NBTE is strongly associated with **hypercoagulable states**. It is frequently seen in patients with advanced malignancies (especially mucinous adenocarcinomas—known as **Trousseau syndrome**) or profound debilitation (wasting/marasmus) [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Morphology:** Vegetations are sterile, bland, and do not cause significant valvular destruction (unlike Infective Endocarditis) [1]. * **Associations:** Look for keywords like "Adenocarcinoma of Pancreas," "Disseminated Intravascular Coagulation (DIC)," or "Cachexia." * **Libman-Sacks Endocarditis vs. NBTE:** Both are sterile, but Libman-Sacks (associated with SLE) features vegetations on *both* sides of the valve leaflets and chordae tendineae [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 568.

Question 127: McCallum's patch is diagnostic of which condition?

A. Infective endocarditis
B. Rheumatic endocarditis (Correct Answer)
C. Myocardial infarction
D. Tetralogy of Fallot

Explanation: **MacCallum’s Patch** is a classic morphological feature of **Rheumatic Heart Disease (RHD)** [1]. It represents an area of endocardial thickening caused by the mechanical trauma of regurgitant blood jets. 1. **Why Rheumatic Endocarditis is correct:** In Acute Rheumatic Fever, endocarditis primarily affects the valves, but it can also involve the mural endocardium [1]. MacCallum’s patch is typically found in the **posterior wall of the left atrium**, just above the posterior leaflet of the mitral valve. It occurs due to subendocardial inflammation (Aschoff bodies) followed by fibrosis, exacerbated by the "jet effect" of mitral regurgitation [1]. [1] 2. **Why other options are incorrect:** * **Infective Endocarditis:** Characterized by large, friable, and bulky **vegetations** (verrucae) on the valve leaflets, which may lead to perforation or abscess, but not MacCallum’s patches [1]. * **Myocardial Infarction:** Involves coagulative necrosis of the myocardium due to ischemia. * **Tetralogy of Fallot:** A congenital cyanotic heart disease characterized by four specific anatomical defects (VSD, pulmonary stenosis, overriding aorta, and RVH). **High-Yield Clinical Pearls for NEET-PG:** * **Aschoff Bodies:** The pathognomonic microscopic feature of RHD (contains Anitschkow cells/Caterpillar cells) [1]. * **Location:** MacCallum’s patch is most common in the **Left Atrium**. * **Vegetations in RHD:** Small, sterile, friable, and arranged in a **row along the line of closure** of the valves [1]. * **Fish-mouth/Button-hole deformity:** Refers to the chronic stage of RHD with mitral valve stenosis [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 566-568.

Question 128: Which of the following is true about Libman-Sacks endocarditis?

A. Vegetations are along the line of valve closure
B. Vegetations are on either side of the valve leaflet (Correct Answer)
C. Vegetations are non-friable
D. Organisms are consistently seen in the vegetations

Explanation: **Explanation:** **Libman-Sacks Endocarditis (LSE)** is a form of non-bacterial thrombotic endocarditis (NBTE) classically associated with **Systemic Lupus Erythematosus (SLE)** and occasionally Antiphospholipid Syndrome [1]. **Why Option B is correct:** The hallmark pathological feature of Libman-Sacks endocarditis is the presence of small, sterile, pinkish vegetations that can occur **anywhere on the valve surface**, including the undersurfaces (ventricular surface) of the leaflets, the chordae tendineae, or the endocardial surfaces [1]. This "random" distribution on **both sides of the valve leaflet** distinguishes it from other types of endocarditis [2]. **Analysis of Incorrect Options:** * **Option A:** Vegetations along the **line of closure** are characteristic of Rheumatic Heart Disease (small, firm verrucae) and NBTE associated with malignancy/wasting [2]. * **Option C:** LSE vegetations are typically **friable** (easily crumbled), which can lead to embolic phenomena [3], although they are less likely to cause significant valvular destruction compared to infective endocarditis. * **Option D:** LSE is a **sterile** endocarditis [1]. The vegetations consist of fibrin, platelets, and immune complexes; the presence of organisms would indicate Infective Endocarditis. **High-Yield Clinical Pearls for NEET-PG:** * **Association:** Strongly linked to SLE (Libman-Sacks = SLE) [3]. * **Microscopy:** Shows intense valvulitis with **fibrinoid necrosis** and often "Hematoxylin bodies" (LE bodies). * **Most Common Valve:** Mitral valve is most frequently involved [1]. * **Clinical Impact:** Usually asymptomatic, but can lead to mitral regurgitation or systemic emboli [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 570. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 568. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of the Immune System, pp. 232-233.

Question 129: Which of the following does NOT cause coronary occlusion?

A. Atheromatous narrowing of the vessel
B. Atheromatous narrowing of the vessel
C. Rupture of an atheromatous plaque into the lumen
D. Organization of a thrombus (Correct Answer)

Explanation: **Explanation:** The core concept in coronary artery disease is the progression from a stable plaque to an acute coronary syndrome (ACS). **Coronary occlusion** refers to the active process of blocking blood flow, leading to myocardial ischemia or infarction [2]. **Why "Organization of a thrombus" is the correct answer:** Organization is a **healing process**, not an occlusive one [4]. When a thrombus forms, the body attempts to repair it through "organization and recanalization." During this process, ingrowth of fibroblasts and capillaries occurs, which eventually creates small new channels (recanalization) through the old clot. This actually helps to **restore** some degree of blood flow through a previously blocked segment, rather than causing a new occlusion [4]. **Analysis of Incorrect Options:** * **Atheromatous narrowing:** This is the most common cause of chronic ischemic heart disease. A fixed obstruction (usually >70% stenosis) limits blood flow, especially during increased demand. * **Plaque Rupture/Hemorrhage:** This is a "dynamic" event. When a plaque ruptures, it exposes highly thrombogenic subendothelial collagen, leading to the rapid formation of a thrombus that acutely occludes the lumen [1]. * **Thrombosis:** Superimposed thrombosis on an ulcerated plaque is the primary mechanism behind Acute Myocardial Infarction (AMI) [1]. **NEET-PG High-Yield Pearls:** * **Critical Stenosis:** Defined as **70-75%** reduction in the cross-sectional area of a coronary artery; at this point, resting flow is adequate, but flow cannot increase during exertion (Stable Angina). * **Vulnerable Plaque:** A plaque with a large lipid core and a thin fibrous cap is most prone to rupture. * **Most common site of occlusion:** Left Anterior Descending (LAD) artery (40-50%), followed by the Right Coronary Artery (RCA) [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of Infancy and Childhood, pp. 508-509. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 288-289. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 550-552. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Hemodynamic Disorders, Thromboembolic Disease, and Shock, pp. 135-136.

Question 130: All the statements regarding atherosclerosis are true, except:

A. Naked eye changes are not visible for the first 12 hours.
B. Triphenyl tetrazolium chloride can help in detecting infracted area.
C. Most commonly involves the left coronary artery.
D. Common site is the anterior wall of the right ventricle. (Correct Answer)

Explanation: **Explanation:** The question asks for the **incorrect** statement regarding atherosclerosis and its sequelae (specifically Myocardial Infarction). **Why Option D is the Correct Answer (The False Statement):** The most common site for myocardial infarction is the **Anterior wall of the Left Ventricle** (near the apex), usually due to the occlusion of the **Left Anterior Descending (LAD) artery** [1]. The right ventricle is relatively resistant to infarction because it has a lower muscle mass, lower oxygen demand, and receives blood flow during both systole and diastole. **Analysis of Other Options:** * **Option A:** In the first **0–12 hours**, there are no reliable gross (naked eye) changes visible in a myocardial infarct [2]. Light microscopy may show wavy fibers, but macroscopic pallor only begins to appear after 12–24 hours [2]. * **Option B:** **Triphenyl Tetrazolium Chloride (TTC)** is a histochemical stain used on fresh heart slices. It reacts with lactate dehydrogenase (LDH) in viable tissue to turn it **brick red** [3]. Infarcted areas lack these enzymes and remain **pale/uncolored**, allowing for early detection (within 2–3 hours post-mortem) [3]. * **Option C:** The **Left Coronary Artery** (specifically its LAD branch) is the most frequently involved vessel in atherosclerosis leading to MI, followed by the Right Coronary Artery and the Left Circumflex Artery [4]. **NEET-PG High-Yield Pearls:** 1. **Order of frequency of arterial occlusion:** LAD (40-50%) > RCA (30-40%) > Left Circumflex (15-20%). 2. **Earliest microscopic change:** Wavy fibers (1-3 hours) [2]. 3. **Contraction band necrosis:** Seen in reperfusion injury. 4. **Most sensitive biomarker:** Cardiac Troponin I (cTnI) [5]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 286-288. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, p. 552. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 552-554. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 550-552. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Cardiovascular Disease, pp. 288-289.

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