Cardiac Pathology Practice Questions

Q: Which of the following is NOT a cause of myocarditis?

Mycobacterium tuberculosis. **Explanation:** The correct answer is **B. Mycobacterium tuberculosis**. While *Mycobacterium tuberculosis* (TB) frequently involves the heart, it characteristically affects the **pericardium** (causing chronic constrictive pericarditis), not the myocardium [2]. Myocarditis is defined as inflammation of the heart muscle, and TB is an extremely rare cause of primary myocardial inflammation. **Analysis of Options:** * **A. Trichinosis:** *Trichinella spiralis* is the most common helminthic cause of myocarditis worldwide. It typically presents with eosinophilic infiltration of the myocardium. * **C. Corynebacterium diphtheriae:** This is a classic bacterial cause of myocarditis. The damage is mediated by the **diphtheria exotoxin**, which inhibits protein synthesis (via ADP-ribosylation of EF-2), leading to fatty change and necrosis of myocytes in up to 25% of patients. * **D. Systemic Lupus Erythematosus (SLE):** SLE is a well-known non-infectious cause of myocarditis [2]. It can cause inflammation across all layers of the heart (pancarditis), though **Libman-Sacks endocarditis** (sterile vegetations) is its most characteristic cardiac manifestation. **NEET-PG High-Yield Pearls:** * **Most common cause of myocarditis:** Viral infections, specifically **Coxsackievirus B** [1]. * **Chagas Disease:** Caused by *Trypanosoma cruzi*; it is a major cause of myocarditis in South America [1]. * **Giant Cell Myocarditis:** A rare, rapidly fatal form characterized by multinucleated giant cells and extensive necrosis [1]. * **Hypersensitivity Myocarditis:** Often drug-induced (e.g., sulfonamides, diuretics) and histologically marked by **eosinophils** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 578-579. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 581-582.

Q: Fibrous scar in myocardial infarction is well established by which time frame?

6 weeks. The healing process of Myocardial Infarction (MI) follows a predictable chronological sequence of inflammation, repair, and remodeling [1]. **Explanation of the Correct Answer:** **Option A (6 weeks)** is correct because the replacement of necrotic myocardium with a **dense, fibrous collagenous scar** is typically well-established by the end of the 6th to 8th week [1]. By this stage, the highly vascularized granulation tissue has been replaced by relatively acellular, white collagenous tissue, marking the completion of the healing phase [1]. **Analysis of Incorrect Options:** * **Option C (6 days):** At this stage, the heart is characterized by **early granulation tissue** at the edges, extensive macrophage infiltration, and the beginning of collagen deposition [1]. The tissue is soft and structurally weak, making this the peak period for myocardial rupture [1]. * **Option D (30 days):** By one month, the scar is forming and maturing, but the process of collagen cross-linking and contraction is still ongoing [1]. It is not considered "well-established" until the 6-week mark. * **Option B (6 months):** While the scar may undergo further thinning or remodeling over months, the definitive fibrous scar is already fully formed much earlier (by 6–8 weeks) [1]. **High-Yield Clinical Pearls for NEET-PG:** * **0–24 hours:** Coagulative necrosis and wavy fibers [1]. * **1–3 days:** Peak neutrophilic infiltration (Yellow-tan center) [1]. * **3–7 days:** Peak macrophage activity; highest risk of **free wall rupture**, VSD, or papillary muscle rupture [1]. * **1–2 weeks:** Maximum granulation tissue formation [1]. * **Modification:** Factors like large infarct size, advanced age, or steroid use can delay this healing timeline. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 552-554.

Q: Occlusion of the anterior descending branch of the left coronary artery will lead to infarction of which area?

Anterior wall of the left ventricle. **Explanation:** The **Left Anterior Descending (LAD) artery**, often referred to as the "widow-maker," is the most common site of coronary artery occlusion (40–50%). It primarily supplies the **anterior wall of the left ventricle**, the **anterior 2/3rd of the interventricular septum**, and the cardiac apex [1]. Therefore, an occlusion in this branch directly results in an anteroseptal or anterior wall myocardial infarction [2]. **Analysis of Incorrect Options:** * **Option A (Posterior wall of the interventricular septum):** This area, along with the posterior wall of the left ventricle, is typically supplied by the **Posterior Descending Artery (PDA)**. In 85% of individuals (right dominance), the PDA arises from the Right Coronary Artery (RCA) [1]. * **Option C (Lateral wall of the heart):** The lateral wall of the left ventricle is supplied by the **Left Circumflex Artery (LCX)**. Occlusion here leads to a lateral wall MI. * **Option D (Inferior surface of the right ventricle):** The right ventricular wall and the inferior (diaphragmatic) surface of the heart are supplied by the **Right Coronary Artery (RCA)** [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Frequency of Occlusion:** LAD (40-50%) > RCA (30-40%) > LCX (15-20%). * **ECG Correlations:** * LAD occlusion: ST elevation in leads **V1–V4**. * LCX occlusion: ST elevation in leads **I, aVL, V5, V6**. * RCA occlusion: ST elevation in leads **II, III, aVF**. * **Papillary Muscle Rupture:** The posteromedial papillary muscle has a single blood supply (RCA), making it more prone to rupture than the anterolateral muscle (dual supply from LAD/LCX). **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. 286-288.

Q: All of the following are causes of myocarditis except:

Mycobacterium tuberculosis. **Explanation:** The correct answer is **B. Mycobacterium tuberculosis**. In pathology, **myocarditis** is defined as an inflammation of the heart muscle (myocardium) that causes injury without an underlying ischemic cause [1]. While *Mycobacterium tuberculosis* (TB) frequently involves the cardiovascular system, it characteristically causes **pericarditis** (specifically chronic constrictive pericarditis) rather than primary myocarditis. While rare myocardial tuberculomas can occur, TB is not classified as a standard cause of infectious myocarditis in medical literature or standard textbooks like Robbins Pathology. **Analysis of Incorrect Options:** * **A. Trichinosis:** *Trichinella spiralis* is the most common helminthic cause of myocarditis worldwide. * **C. Borrelia:** *Borrelia burgdorferi* (Lyme disease) is a well-known cause of "Lyme Carditis," which often manifests as conduction blocks (AV blocks) due to myocardial inflammation. * **D. CMV:** Cytomegalovirus is a significant viral cause of myocarditis, particularly in immunocompromised patients and post-transplant recipients [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause overall:** Viral infections, specifically **Coxsackievirus B** [1]. * **Chagas Disease:** Caused by *Trypanosoma cruzi*; it is the most common cause of myocarditis in endemic areas (South America) [1]. * **Diphtheritic Myocarditis:** Caused by the *Corynebacterium diphtheriae* exotoxin; it is a major cause of death in diphtheria patients. * **Hypersensitivity Myocarditis:** Characterized by an **eosinophilic infiltrate**, usually due to drug reactions (e.g., sulfonamides) [1]. * **Giant Cell Myocarditis:** A rare, aggressive form with a poor prognosis, characterized by multinucleated giant cells and extensive necrosis [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Heart, pp. 578-581.

Question 1

Vegetations on the undersurface of A.V. valves are found in which condition?

Accepted Answer

Libman-Sack's endocarditis

Answer

Acute rheumatic fever

Answer

Non-bacterial thrombotic endocarditis

Answer

Chronic rheumatic carditis

Question 2

Which of the following is NOT a cause of myocarditis?

Accepted Answer

Mycobacterium tuberculosis

Answer

Trichinosis

Answer

Corynebacterium diphtheriae

Answer

Systemic lupus erythematosus

Question 3

Antishkow's cells are seen in which condition?

Accepted Answer

Rheumatic heart disease

Answer

Rheumatic arthritis

Answer

Bacterial endocarditis

Answer

Marantic endocarditis

Question 4

The commonest type of pericarditis in acute rheumatic fever is?

Accepted Answer

Fibrinous

Answer

Serous

Answer

Serofibrinous

Answer

Purulent

Question 5

Which statement is false regarding Non-Bacterial Thrombotic Embolism (NBTE)?

Accepted Answer

Vegetations elicit an inflammatory reaction

Answer

Marantic endocarditis

Answer

Thrombi on the leaflets of the cardiac valves

Answer

Non-invasive in nature

Question 6

Antitschkow cells in acute rheumatic fever are derived from which cell type?

Accepted Answer

Macrophages

Answer

Lymphocytes

Answer

Histiocytes

Answer

Neutrophils

Question 7

Fibrous scar in myocardial infarction is well established by which time frame?

Accepted Answer

6 weeks

Answer

6 months

Answer

6 days

Answer

30 days

Question 8

Occlusion of the anterior descending branch of the left coronary artery will lead to infarction of which area?

Accepted Answer

Anterior wall of the left ventricle

Answer

Posterior wall of the interventricular septum

Answer

Lateral wall of the heart

Answer

Inferior surface of the right ventricle

Question 9

Flat vegetations in pockets of valves are due to?

Accepted Answer

Rheumatic heart disease

Answer

Non-bacterial thrombotic endocarditis (NBTE)

Answer

Infective endocarditis

Question 10

All of the following are causes of myocarditis except:

Accepted Answer

Mycobacterium tuberculosis

Answer

Trichinosis

Answer

Borrelia

Answer

CMV

Cardiac Pathology — MCQs

Cardiac Pathology — MCQs

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