PA26.1-10 | Cardiovascular System — Graded Quiz

A 55-year-old man with hypertension and type 2 diabetes undergoes carotid endarterectomy. The surgical specimen shows a fibrous plaque with a thin fibrous cap (< 65 µm), a large necrotic lipid core, inflammatory macrophage infiltration at the cap shoulder, and intraplaque haemorrhage. These morphological features are collectively termed the 'vulnerable plaque'. Which mechanism most directly links these features to the risk of acute coronary syndrome rather than stable angina?

A 73-year-old hypertensive man presents with sudden-onset tearing pain radiating from the chest to the back. CT aortography reveals a double lumen in the thoracic aorta with an intimal tear just distal to the aortic valve. His blood pressure is 190/110 mmHg. Histological examination of the aortic wall would most likely show which change in the tunica media?

A 58-year-old man presents 8 hours after the onset of crushing substernal chest pain. Serial ECGs show evolving ST elevation in leads II, III, and aVF, and troponin T is markedly elevated. Primary PCI achieves TIMI 3 flow. On day 3 post-procedure he develops a new grade 3/6 pansystolic murmur at the lower sternal border, louder on inspiration, with a right ventricular heave. Echocardiography shows a defect in the interventricular septum. Which pathological event best explains the timing and mechanism of this complication?

A 60-year-old woman with longstanding mitral stenosis due to rheumatic heart disease develops progressive dyspnoea, orthopnoea, and bilateral ankle oedema. Chest X-ray shows cardiomegaly, upper lobe venous diversion, Kerley B lines, and a double right heart border. Her BNP is 1,200 pg/mL. The Kerley B lines seen on X-ray are best explained by which pathological process in the lung?

A 14-year-old girl presents with a 2-week history of migratory polyarthritis, a new apical pansystolic murmur, and an erythematous rash on her trunk. Throat culture taken 5 weeks ago grew Group A beta-haemolytic Streptococcus. ASO titre is markedly elevated. Echocardiography shows mitral regurgitation. Which morphological lesion, if found on biopsy of the myocardium, would be pathognomonic of this diagnosis and represent the histological hallmark of the disease?

A 28-year-old intravenous drug user presents with a 10-day history of high-grade fever, rigors, and a new loud pansystolic murmur at the left lower sternal border that increases on inspiration. Blood cultures grow Staphylococcus aureus. Echocardiography reveals vegetations on the tricuspid valve with evidence of right heart volume overload. Which complication is most likely to occur specifically due to the right-sided location of these vegetations?

A 6-week-old infant is referred for failure to thrive and feeding difficulties. On examination there is a loud continuous 'machinery' murmur below the left clavicle, bounding pulses, and a wide pulse pressure. Echocardiography reveals a large patent ductus arteriosus (PDA) with left-to-right shunting. The parents ask why the baby has become breathless and sweaty during feeds but is not cyanosed. Which pathophysiological explanation best accounts for the absence of cyanosis in this infant with a significant cardiac shunt?

A 35-year-old man presents with a 2-year history of progressive dyspnoea and a family history of sudden cardiac death in his father at age 38 and his paternal uncle at age 42. Echocardiography shows asymmetric septal hypertrophy (septum 22 mm, posterior wall 10 mm) with systolic anterior motion of the mitral valve (SAM) and a dynamic left ventricular outflow tract gradient of 55 mmHg at rest. Genetic testing reveals a missense mutation in the MYH7 gene (encoding beta-myosin heavy chain). Why does this particular lesion cause dynamic — rather than fixed — obstruction of the left ventricular outflow tract?

A 70-year-old woman with known dilated cardiomyopathy (EF 20%) and longstanding biventricular failure is admitted with massive ascites, peripheral oedema, and jaundice. Liver biopsy shows congestion of hepatic sinusoids with hepatocyte atrophy and eosinophilic change at the central vein zones, giving a mottled 'nutmeg' appearance on gross inspection. Her INR is 2.1 despite no anticoagulation. Which pathological mechanism best explains the coagulopathy and the centrilobular pattern of liver injury in this patient?

An autopsy is performed on a 48-year-old man who died suddenly during exercise. Gross examination shows a massive, firm, pale yellow tumour measuring 14 × 11 cm in the left atrium, attached by a pedicle to the fossa ovalis and prolapsing intermittently into the mitral orifice during systole. Microscopically, the mass shows stellate and polygonal cells embedded in a loose myxoid stroma with abundant mucopolysaccharides. No significant mitotic activity is seen. Which of the following best explains why this tumour caused syncopal episodes intermittently related to body position during the months before death?

A 78-year-old woman with a 40-year history of poorly controlled hypertension develops acute pulmonary oedema. Her chest X-ray shows bilateral perihilar 'bat-wing' alveolar opacities with an upper lobe venous blood diversion pattern. On examination she has a fourth heart sound (S4) and signs of pulmonary venous hypertension, but the left ventricular ejection fraction is preserved at 62% on echocardiography. Which pathological sequence best explains how decades of hypertension can cause pulmonary oedema with a preserved ejection fraction?

A gross pathology specimen from a 66-year-old man who died of biventricular failure shows both ventricles dilated, with a spherical cardiac silhouette and a combined heart weight of 810 g (normal ~300 g). All valves appear structurally normal. The myocardium appears pale, flabby, and diffusely thinned. There is a mural thrombus in the left ventricular apex. The patient had a 30-year history of heavy alcohol use with no coronary artery disease found at autopsy. Which microscopic finding would most specifically point to alcoholic cardiomyopathy rather than idiopathic dilated cardiomyopathy in this specimen?