- A 50-year-old man with chronic hypertension is started on an ACE inhibitor. Three days later his serum creatinine rises from 1.1 mg/dL to 2.4 mg/dL. Blood pressure is 142/88 mm Hg, and physical examination reveals an abdominal bruit to the right of the midline. Which of the following mechanisms best explains the decline in renal function after initiating therapy?
Answer: Loss of efferent arteriolar vasoconstriction reducing glomerular capillary pressure in a kidney already hypoperfused by renal artery stenosis
When you encounter acute kidney injury after starting an ACE inhibitor, especially with an abdominal bruit, think renal artery stenosis. This clinical scenario tests your understanding of how kidneys maintain glomerular filtration when blood supply is compromised.
In renal artery stenosis, the affected kidney receives reduced blood flow. To maintain glomerular filtration pressure, the kidney compensates by constricting the efferent arteriole (the vessel leaving the glomerulus). This creates a "backup" of pressure within the glomerular capillaries, preserving filtration despite poor perfusion. This compensation depends on angiotensin II, which preferentially constricts efferent arterioles.
ACE inhibitors block angiotensin II production, eliminating this crucial compensatory mechanism. Without efferent arteriolar constriction, glomerular capillary pressure drops precipitously in the stenotic kidney, causing acute kidney injury. The abdominal bruit confirms renal artery stenosis, and the rapid creatinine rise (1.1 to 2.4 mg/dL in 3 days) is classic for this mechanism. Answer A correctly describes this pathophysiology.
B is wrong because drug-induced interstitial nephritis typically develops over weeks, not days, and wouldn't correlate with the bruit. C is incorrect because his blood pressure remains elevated (142/88), ruling out systemic hypotension causing tubular necrosis. D fails because volume contraction from natriuresis wouldn't cause such dramatic, rapid kidney injury in someone with normal kidney function.
Key takeaway: ACE inhibitor + acute kidney injury + abdominal bruit = renal artery stenosis with loss of angiotensin II-mediated efferent arteriolar compensation. Always consider renovascular disease when ACE inhibitors cause rapid kidney function decline.
- The transition from stable to unstable angina in this patient is most likely due to which of the following events involving a coronary artery plaque?
Answer: Rupture of the plaque with superimposed thrombosis
Stable angina is caused by a fixed atherosclerotic stenosis (>70%) that limits blood flow during increased demand. The transition to unstable angina, a form of acute coronary syndrome, is typically caused by an acute plaque change. This most often involves the rupture or erosion of an atherosclerotic plaque, which exposes the thrombogenic lipid core to the blood. This triggers the formation of a non-occlusive thrombus that can cause myocardial ischemia even at rest.
- A 65-year-old man with a history of coronary artery disease suddenly develops severe abdominal and back pain. Blood pressure is 85/50 mm Hg, and heart rate is 120/min. Physical examination reveals a pulsatile mass superior to the umbilicus. He dies shortly after arrival. Autopsy shows a 7-cm infrarenal abdominal aortic aneurysm that ruptured posteriorly. Which of the following processes most likely initiated formation of this aneurysm?
Answer: Atherosclerotic destruction of tunica media elastic lamellae in the abdominal aorta leading to progressive wall weakness
When you encounter a question about abdominal aortic aneurysms (AAAs), think about location, demographics, and underlying pathophysiology. AAAs typically occur in elderly patients with cardiovascular risk factors and have distinct mechanisms compared to thoracic aneurysms.
This patient presents with classic ruptured AAA: elderly male with coronary disease, severe abdominal/back pain, hypotension, and a pulsatile abdominal mass. The autopsy confirms a large infrarenal AAA. The key is understanding what causes AAAs to form.
Answer A is correct because atherosclerosis is the primary cause of infrarenal abdominal aortic aneurysms. Atherosclerotic plaques damage the tunica media by destroying elastic lamellae and smooth muscle cells, weakening the arterial wall. This process specifically affects the infrarenal aorta due to differences in wall structure and hemodynamics compared to other aortic segments.
Answer B describes Marfan syndrome pathology (fibrillin-1 defects causing cystic medial necrosis), which typically affects the ascending aorta, not the infrarenal abdominal aorta. Answer C describes Takayasu arteritis, which primarily involves the aortic arch and its branches, causing stenosis rather than aneurysmal dilation. Answer D describes tertiary syphilis (luetic aortitis), which characteristically affects the ascending aorta with "tree-bark" scarring, not the abdominal aorta.
Remember this pattern: atherosclerotic aneurysms occur in the infrarenal abdominal aorta in elderly patients, while genetic disorders (Marfan) and infections (syphilis) typically affect the thoracic aorta. Location is crucial for determining etiology.
- The accumulation of these lipid-laden cells, known as foam cells, is a direct result of the unregulated uptake of which of the following?
Answer: Oxidized low-density lipoprotein (LDL)
Foam cells are a hallmark of atherosclerotic plaques. They are formed when macrophages in the intima engulf modified (primarily oxidized) LDL particles. This uptake occurs via scavenger receptors (e.g., SR-A, CD36) on the macrophage surface, which, unlike the native LDL receptor, are not downregulated by intracellular cholesterol levels. This leads to unregulated and massive lipid accumulation within the macrophages, transforming them into foam cells.
- A 47-year-old man is evaluated for exercise-induced calf pain that resolves with rest. He has a 30-pack-year smoking history and hyperlipidemia. An ankle–brachial index (ABI) measured after treadmill testing is 0.55 on the right and 0.58 on the left. Which of the following pathophysiologic processes is primarily responsible for this patient's symptoms and ABI findings?
Answer: Progressive intimal fibro-fatty plaque formation leading to critical stenosis of large elastic and muscular arteries supplying the lower extremities
When you encounter a patient with exercise-induced leg pain that resolves with rest (intermittent claudication) plus risk factors like smoking and hyperlipidemia, think peripheral artery disease (PAD). The low ankle-brachial index (ABI) values of 0.55-0.58 confirm significant arterial stenosis, as normal ABI is 1.0-1.4.
The pathophysiology underlying PAD is atherosclerosis - the progressive formation of fibro-fatty plaques in the intimal layer of arteries. These plaques contain lipids, smooth muscle cells, and inflammatory cells that gradually narrow the arterial lumen. When stenosis becomes critical (typically >70% luminal narrowing), blood flow becomes inadequate to meet metabolic demands during exercise, causing the characteristic cramping pain that resolves with rest. This process primarily affects large elastic and muscular arteries supplying the extremities.
Choice A correctly describes this atherosclerotic process. Choice B describes thromboangiitis obliterans (Buerger's disease), which affects younger smokers and involves inflammatory thrombosis of smaller vessels with venous involvement - not the classic presentation here. Choice C describes Mönckeberg's arteriosclerosis, which causes medial calcification without luminal narrowing and wouldn't produce these symptoms or low ABI values. Choice D describes vasospasm (like Raynaud's phenomenon), which typically affects digits and isn't exercise-induced or associated with consistently low ABI measurements.
Remember: intermittent claudication + smoking history + low ABI = atherosclerotic PAD. The key distinguishing feature is that symptoms are reproducibly triggered by a consistent amount of exercise and relieved by rest.
- The hypertension in this patient is primarily driven by the increased secretion of which substance from the juxtaglomerular cells of the affected kidney?
Answer: Renin
Renal artery stenosis reduces blood flow and perfusion pressure to the downstream kidney. The juxtaglomerular apparatus (JGA) in that kidney senses this reduced pressure as systemic hypotension and responds by increasing the secretion of renin. Renin is an enzyme that cleaves angiotensinogen to angiotensin I, initiating the renin-angiotensin-aldosterone system (RAAS) cascade. The resulting increase in angiotensin II and aldosterone leads to systemic vasoconstriction and sodium/water retention, causing secondary hypertension.
- This patient's postoperative immobility is a major risk factor for her current condition primarily by promoting which of the following?
Answer: Venous stasis
The patient has a deep vein thrombosis (DVT), and her risk is explained by Virchow's triad (stasis, endothelial injury, hypercoagulability). Postoperative immobility is a key risk factor for DVT, and its primary contribution is promoting venous stasis. The contraction of calf muscles during walking is crucial for pumping venous blood from the lower extremities back to the heart. Lack of this 'muscle pump' activity leads to pooling of blood in the deep veins, which is a major factor promoting thrombus formation.
- A 40-year-old woman presents with episodic headaches, palpitations, and sweating. During an episode, blood pressure is 220/120 mm Hg and pulse is 104/min. Plasma metanephrines are markedly elevated. Which of the following vascular changes is most likely to develop if her condition remains untreated?
Answer: Hyperplastic arteriolosclerosis with concentric laminated thickening of arteriolar walls throughout systemic circulation
When you encounter a patient with episodic hypertension, palpitations, and elevated metanephrines, think pheochromocytoma. This catecholamine-secreting tumor causes severe, intermittent hypertensive episodes that can lead to specific vascular pathology if untreated.
The key insight here is understanding how severe hypertension damages blood vessels. Pheochromocytoma causes acute, extreme blood pressure spikes (as seen with this patient's 220/120 mm Hg reading) that trigger acute arterial necrosis. When arterioles are subjected to these sudden, severe pressure increases, smooth muscle cells in the vessel walls undergo acute necrosis and are replaced by proliferating smooth muscle cells, creating the characteristic "onion-skin" appearance of hyperplastic arteriolosclerosis.
Choice A correctly describes this hyperplastic arteriolosclerosis - the concentric laminated thickening results from smooth muscle cell proliferation in response to acute vascular injury from catecholamine surges.
Choice B describes hyaline arteriolosclerosis, which occurs in chronic, moderate hypertension and diabetes - not the acute, severe spikes of pheochromocytoma.
Choice C describes Mönckeberg's sclerosis, a age-related medial calcification unrelated to hypertensive damage.
Choice D describes cystic medial necrosis of the aorta, associated with conditions like Marfan syndrome or bicuspid aortic valve, not catecholamine excess.
Remember: acute, severe hypertension (like pheochromocytoma) causes hyperplastic arteriolosclerosis, while chronic moderate hypertension causes hyaline arteriolosclerosis. The severity and pattern of blood pressure elevation determines the type of vascular pathology.
- Which of the following is the most significant predisposing factor for this patient's condition?
Answer: Chronic hypertension
This patient's presentation is classic for an acute aortic dissection. The most common and important predisposing factor for aortic dissection is chronic hypertension. Hypertension causes hyaline arteriolosclerosis of the vasa vasorum, leading to decreased blood flow to the aortic media. This results in atrophy and weakening of the medial layer, predisposing it to intimal tears and dissection.
- A 58-year-old man with long-standing poorly controlled hypertension and type 2 diabetes presents with progressive renal insufficiency. Biopsy of an interlobular renal artery shows homogeneous eosinophilic thickening and luminal narrowing without inflammation. Which of the following hemodynamic consequences best explains the vascular change observed?
Answer: Chronic endothelial injury from elevated pressures causing plasma protein leakage into arteriolar walls and smooth muscle matrix production
When you encounter renal vascular pathology in the context of chronic hypertension and diabetes, focus on distinguishing between hyaline arteriolosclerosis and hyperplastic arteriolosclerosis based on the clinical presentation and histologic description.
The key phrase here is "homogeneous eosinophilic thickening without inflammation" in a patient with chronic, poorly controlled hypertension and diabetes. This describes hyaline arteriolosclerosis, where chronic elevation in blood pressure causes ongoing endothelial injury. The damaged endothelium becomes "leaky," allowing plasma proteins to seep into the vessel wall. Smooth muscle cells respond by producing excess extracellular matrix, creating the characteristic homogeneous, pink (eosinophilic) appearance on microscopy. This makes option A correct.
Option B describes hyperplastic arteriolosclerosis ("onion-skinning"), which occurs with acute, severe hypertension and presents as concentric layers of smooth muscle proliferation rather than homogeneous thickening. Option C suggests immune complex vasculitis, but the absence of inflammation rules this out entirely. Option D incorrectly associates lipohyaline changes with aneurysm formation and hypertriglyceridemia, when hyaline arteriolosclerosis actually causes luminal narrowing and is related to hypertension and diabetes.
Remember that chronic conditions (long-standing hypertension/diabetes) typically produce hyaline arteriolosclerosis with homogeneous thickening, while acute severe hypertension causes hyperplastic arteriolosclerosis with "onion-skin" layering. The presence or absence of inflammation helps distinguish vascular hypertensive changes from immune-mediated vasculitis.
- A 45-year-old woman with poorly controlled hypertension develops sudden, severe headache and vomiting. CT scan shows an intracerebral hemorrhage in the basal ganglia. Which of the following vascular lesions most likely precipitated the bleed?
Answer: Charcot–Bouchard microaneurysm of a lenticulostriate artery caused by chronic hypertension-induced wall weakening
When you encounter intracerebral hemorrhage questions, focus on matching the bleeding location with the most likely underlying vascular pathology based on patient demographics and risk factors.
This 45-year-old woman with poorly controlled hypertension and basal ganglia hemorrhage presents a classic scenario. Chronic hypertension causes sustained high pressure in small penetrating arteries, particularly the lenticulostriate arteries that supply the basal ganglia. This chronic stress leads to lipohyalinosis and formation of Charcot-Bouchard microaneurysms - tiny dilations in vessel walls weakened by hypertensive damage. These microaneurysms are prone to rupture, causing the deep intracerebral hemorrhages characteristic of hypertensive bleeding.
Choice A correctly identifies this pathophysiology: Charcot-Bouchard microaneurysms in lenticulostriate arteries are the classic cause of hypertensive basal ganglia hemorrhages.
Choice B describes berry aneurysms, which typically occur at the Circle of Willis and cause subarachnoid hemorrhage, not intracerebral hemorrhage. While polycystic kidney disease is associated with berry aneurysms, the bleeding pattern doesn't match.
Choice C mentions arteriovenous malformations (AVMs), which are developmental lesions that can cause hemorrhage but typically occur in younger patients and aren't specifically associated with hypertension or basal ganglia location.
Choice D describes mycotic aneurysms from endocarditis, which would require evidence of systemic infection and typically affect distal cortical vessels rather than deep penetrating arteries.
Study tip: Remember the "location-pathology" pairing: basal ganglia hemorrhage + hypertension = Charcot-Bouchard microaneurysms. Subarachnoid hemorrhage suggests berry aneurysms, while lobar hemorrhage in elderly patients suggests cerebral amyloid angiopathy.
- A 52-year-old man with a history of untreated hyperlipidemia experiences an acute ST-elevation myocardial infarction. Autopsy months later reveals numerous advanced atherosclerotic plaques in his coronary and carotid arteries. Which of the following factors was most critical in converting a stable, fibrous plaque into the unstable lesion that precipitated his infarction?
Answer: Metalloproteinase secretion by activated macrophages degrading the fibrous cap extracellular matrix
When you encounter questions about acute coronary syndromes, focus on the pathophysiology of plaque rupture—the critical event that transforms stable atherosclerosis into a life-threatening condition.
Plaque rupture occurs when the fibrous cap protecting the lipid core becomes weakened and breaks open, exposing thrombogenic material to circulating blood. This triggers rapid thrombus formation and vessel occlusion. The key mechanism behind cap weakening is inflammatory activity within the plaque. Activated macrophages secrete matrix metalloproteinases (MMPs), which are enzymes that degrade collagen and other structural proteins in the fibrous cap's extracellular matrix. As the cap thins and weakens, it becomes vulnerable to rupture under normal hemodynamic stress.
Choice A correctly identifies this crucial inflammatory pathway—metalloproteinase secretion by activated macrophages degrading the fibrous cap is the primary mechanism converting stable to unstable plaques.
Choice B describes calcification, which actually stabilizes plaques rather than destabilizes them. Calcium deposits make plaques stiffer but less prone to rupture. Choice C incorrectly suggests laminar flow and nitric oxide production contribute to instability, when laminar flow is actually protective and associated with stable endothelium. Choice D describes increased collagen synthesis, which would strengthen rather than weaken the fibrous cap.
Remember this pattern: USMLE Step 1 loves testing the inflammatory basis of atherothrombosis. When you see plaque rupture scenarios, think "macrophages + metalloproteinases = cap degradation." The inflammatory component, not just lipid accumulation, drives the transition from chronic stable disease to acute coronary events.
- This additional test is most likely measuring which of the following?
Answer: Lipoprotein(a) [Lp(a)]
Lipoprotein(a) is an LDL-like particle that is an independent, genetically determined risk factor for atherosclerotic cardiovascular disease. It is often measured in patients with premature or familial ASCVD whose traditional lipid profile does not fully explain their risk. Its structure, particularly the apolipoprotein(a) component, is homologous to plasminogen, which allows it to interfere with fibrinolysis (prothrombotic) and it also promotes atherogenesis by depositing cholesterol in the arterial wall.
- A 63-year-old woman with long-standing poorly controlled hypertension suddenly develops sharp, tearing chest pain that radiates to her interscapular region. Blood pressure is 190/105 mm Hg in the right arm and 162/92 mm Hg in the left arm. A new diastolic murmur is heard over the right sternal border. Which of the following pre-existing vascular abnormalities most likely predisposed this patient to her current condition?
Answer: Cystic medial degeneration of the proximal thoracic aorta associated with hypertension and aging
When you encounter a patient with sudden, severe chest pain radiating to the back plus blood pressure discrepancies between arms, think aortic dissection. The clinical picture here is classic: sharp, tearing pain, interscapular radiation, asymmetric blood pressures, and a new aortic regurgitation murmur.
Aortic dissection occurs when blood separates the layers of the aortic wall, creating a false lumen. This requires a pre-existing weakness in the aortic media. Choice A describes cystic medial degeneration (also called cystic medial necrosis), the most common predisposing factor for aortic dissection. This condition involves loss of smooth muscle cells and elastic fibers in the aortic media, with accumulation of mucoid material. It's accelerated by hypertension and aging, perfectly matching this patient's profile.
Choice B describes atherosclerotic plaques near renal arteries, which could cause renovascular hypertension but wouldn't predispose to aortic dissection. Choice C describes the vascular changes seen in polyarteritis nodosa, a vasculitis affecting medium-sized arteries—not the aorta. Choice D describes atherosclerotic disease with mural thrombi, which could cause embolic phenomena but doesn't weaken the aortic wall structure.
The key insight is that aortic dissection requires structural weakness of the aortic media, not just surface atherosclerotic changes or inflammation elsewhere. Remember that blood pressure differences between arms, especially with chest pain, should immediately make you think aortic dissection. Cystic medial degeneration is the most common underlying pathology, particularly in older hypertensive patients.
- A 30-year-old woman presents with new-onset hypertension during her first trimester of pregnancy. Serum aldosterone is elevated, and plasma renin activity is markedly suppressed. After administration of an aldosterone antagonist, her blood pressure normalizes and serum potassium increases. Which of the following genetic alterations best explains this patient's presentation?
Answer: Chromosomal translocation creating a chimeric fusion of the 11β-hydroxylase and aldosterone synthase genes leading to ACTH-driven aldosterone overproduction
When you encounter hypertension with elevated aldosterone and suppressed renin during pregnancy, think about genetic causes of primary aldosteronism that can be unmasked by pregnancy's physiological changes.
This patient's presentation points to glucocorticoid-remediable aldosteronism (GRA), a rare genetic form of primary aldosteronism. The key insight is that pregnancy increases ACTH levels, which would worsen aldosterone overproduction if aldosterone synthesis becomes ACTH-dependent rather than renin-dependent. Answer C describes exactly this mechanism: a chromosomal crossover creates a chimeric gene where aldosterone synthase comes under the control of the ACTH-responsive 11β-hydroxylase promoter. This makes aldosterone production follow ACTH rhythms instead of responding to renin-angiotensin signaling, explaining the elevated aldosterone with suppressed renin.
Answer A (Liddle syndrome) would cause hypertension and hypokalemia, but aldosterone would be suppressed, not elevated, since the problem is with sodium channels, not mineralocorticoid excess. Answer B (11β-HSD2 deficiency) would also suppress aldosterone since cortisol itself would activate mineralocorticoid receptors. Answer D (WNK1 mutations) causes pseudohypoaldosteronism type II with normal aldosterone levels, not the elevated aldosterone seen here.
The response to aldosterone antagonists confirms this is true mineralocorticoid excess. Remember that GRA often presents or worsens during pregnancy due to increased ACTH drive, making it a classic board scenario for testing your understanding of atypical aldosterone regulation.
- A 46-year-old woman with a history of systemic sclerosis develops progressive dyspnea on exertion and syncope. Right heart catheterization shows mean pulmonary arterial pressure of 36 mm Hg (normal <20 mm Hg) and normal pulmonary capillary wedge pressure. Which of the following structural changes in pulmonary arteries is most characteristic of her condition?
Answer: Intimal proliferation with concentric "onion-skin" fibrosis leading to severe luminal narrowing and plexiform lesions
When you encounter a patient with systemic sclerosis developing dyspnea and syncope with elevated pulmonary arterial pressure but normal wedge pressure, you're looking at pulmonary arterial hypertension (PAH) - specifically, the scleroderma-associated form which is a leading cause of death in these patients.
The hallmark pathological changes in PAH involve progressive remodeling of small pulmonary arteries. Answer A correctly describes the characteristic findings: intimal proliferation creates concentric layers of smooth muscle cells and fibroblasts that give an "onion-skin" appearance on histology. This leads to severe luminal narrowing, and in advanced cases, you see plexiform lesions - complex vascular structures that represent disordered angiogenesis attempting to bypass obstructed vessels.
Answer B describes changes seen in Marfan syndrome affecting the aorta, not pulmonary hypertension. Fibrillin-1 deficiency causes aortic root dilatation and dissection risk, but doesn't cause the intimal proliferation pattern of PAH.
Answer C refers to hyaline arteriolosclerosis from systemic hypertension, which affects systemic arterioles, not pulmonary arteries. This patient's normal wedge pressure rules out left heart disease as the cause.
Answer D describes atherosclerotic changes typical of systemic arteries. Pulmonary arteries rarely develop atherosclerosis, and when PAH does affect larger vessels, it's through different mechanisms than lipid plaque formation.
Remember: PAH in scleroderma patients has a poor prognosis, so early recognition through this classic triad (progressive dyspnea, syncope, elevated PA pressure with normal wedge pressure) is crucial for timely treatment.
- A 32-year-old woman presents with sudden onset of left leg swelling and pain. Doppler ultrasound confirms a deep venous thrombosis (DVT) in the femoral vein. She has no history of prolonged immobilization, surgery, or malignancy. Laboratory testing reveals a point mutation in factor V that renders it resistant to inactivation. Which of the following hemodynamic changes in venous circulation most directly predisposes patients to thrombosis in this setting?
Answer: Reduced blood flow velocity in valve pockets of deep veins promoting localized stasis and increased contact time between coagulation factors and endothelium
When you encounter DVT questions involving inherited thrombophilias like Factor V Leiden, think about Virchow's triad: stasis, hypercoagulability, and endothelial injury. This patient has hypercoagulability from the factor V mutation, but understanding which hemodynamic factor most directly contributes to clot formation is key.
The correct answer is A because venous valve pockets are anatomical sites where blood flow naturally slows and creates stagnant areas. In these pockets, reduced flow velocity allows coagulation factors to accumulate and have prolonged contact with the endothelium. When you have a hypercoagulable state like Factor V Leiden (where factor V resists protein C inactivation), these areas of stasis become particularly dangerous because the normal anticoagulant mechanisms are already impaired.
B is incorrect because arterial hypertension affects arteries, not venous circulation, and DVTs primarily occur in veins where pressure is much lower.
C is wrong because exercise typically improves venous return through muscle pump action and actually reduces DVT risk. Hyperdynamic flow would be protective, not predisposing.
D misses the mark because right heart failure causes venous congestion and edema, but this doesn't directly promote thrombosis. In fact, dilution of clotting factors would theoretically reduce clotting risk.
Remember that DVTs most commonly form in valve pockets and venous sinuses within muscle bellies where stasis naturally occurs. When you see inherited thrombophilias on Step 1, focus on how altered coagulation proteins interact with normal sites of venous stasis.
- Histopathologic examination of this vessel is most likely to reveal which of the following findings?
Answer: Granulomatous inflammation with multinucleated giant cells
The patient's presentation is classic for Giant Cell (Temporal) Arteritis, a large-vessel vasculitis. The characteristic histologic finding on a temporal artery biopsy is granulomatous inflammation of the media, often with fragmentation of the internal elastic lamina and the presence of multinucleated giant cells. This inflammation leads to luminal narrowing and ischemic symptoms like jaw claudication and vision loss.
- This patient's hypertension is most likely caused by a pathologic process primarily affecting which of the following arterial layers?
Answer: Media
This patient's presentation (young female, resistant hypertension, abdominal bruit, high renin) is classic for renovascular hypertension secondary to fibromuscular dysplasia (FMD). FMD is a non-atherosclerotic, non-inflammatory vascular disease that causes stenosis of medium-sized arteries, most commonly the renal arteries. The most common subtype is medial fibroplasia, characterized by alternating areas of thickened fibromuscular ridges and thinned media, leading to the characteristic 'string of beads' appearance on angiography. The primary pathology is within the tunica media.
- The acute end-organ damage seen in this condition is most closely associated with which of the following vascular lesions?
Answer: Fibrinoid necrosis of arterioles
Hypertensive emergency (or malignant hypertension) is characterized by severe blood pressure elevation with evidence of acute end-organ damage (e.g., encephalopathy, acute kidney injury, papilledema). The characteristic vascular lesion is fibrinoid necrosis of small arteries and arterioles. The extreme pressure causes endothelial injury, allowing plasma proteins (including fibrin) to leak into the vessel wall, resulting in vessel damage, thrombosis, and downstream ischemia, which mediates the end-organ damage.
