Lecture 28: Pathology of Hypertension Flashcards
What are the key points of the pathology of HTN?
- Systemic arterial hypertension is a functional state that may produce structural changes in vessels
i. atherosclerosis in large/medium size arteries
ii. fibroelastic intimal hyperplasia of small arteries
iii. hyaline and hyperplastic arteriolitis in arterioles
iv. microaneurysms of cerebral arteries - The structural changes in vessels may produce 2NDary effects in organs:
i. LV hypertrophy
ii. nephrosclerosis in vessels
iii. morbidity/mortality due to CHF or MI
iv. renal failure
v. stroke
vi. ischemic infarcts - Dissecting hematoma of aorta and major arteries occurs in structurally abnormal vessels (medial degeneration), a process accelerated by HTN or Marfan’s syndrome
- produces protean and lethal manifestations
- leads to death from exsanguination or cardiac tamponade
What are the characteristics of benign HTN?
95%
Diastolic > 90 and syst > 140
Silent until late in course (silent killer)
What are the characteristics of malignant hypertension?
5% and follows benign
Diastolic > 120 and systolic >210
Clinically SYMPTOMATIC
LETHAL if not treated rapidly/adequately
What are the key characteristics of secondary HTN?
5-10%
Due to underlying disease, most often from renal or adrenal
What are the key characteristics of primary hypertension?
No identified single cause
Multigene controlled + environmental factors (stress, salt, diet)
What are the vascular changes of HTN?
- acceleration of other vascular diseases like atherosclerosis
- changes unique to hypertension
a. adaptive (vasoconstriction, fibroelastic intimal hyperplasia)
b. destructive (fibrinoid necrosis, hyperplastic arteriolitis)
- seen with malignant HTN only
What are the adaptive changes of benign HTN?
- vasoconstriction
- Fibroelastic intimal hyperplasia (small arteries in the kidneys)
- medial hypertrophy of large and medium arteries
What causes particularly bad nephroarteriosclerosis?
HTN + Diabetes!
Remember diabetes leads to nephropathy as well
What are the characteristics of fibrinoid necrosis?
A type of destructive change in malignant HTN
Characterized by deposition of fibrin in arterioles
Associated with necrosis in endothelial and SMCs
What are the characteristics of hyperplastic arteriolitis?
Concentric proliferation of SMCs
Interstitial proteoglycan deposition in small arteries (onion skinning)
Driven by growth factors such as PDGF
What are the characterisitcs of microangiopathic hemolytic anemia?
Shearing off of red cell fragments
Results in shistocytes with bites taken out
Occurs due to passage through fibrin mesh at increased pressures
What characterizes the early lesion of atherosclerosis?
Fatty streaks (the yellow in the descending aorta)
What are the histological features of hyaline atherosclerosis?
Adaptive change of HTN
Thick pink layer around the lumen of the arteriole
What are the histological features of
Intimal fibroelastic hyperplasia?
Presence of brown squiggly lines in the
Tunica intima
Narrowing of the lumen of a small renal artery
Whats the difference between a functional and a structural change?
The former is reversible
The latter is irreversible
What an example of a functional (and sometimes structural) change?
Vasoconstriction
Medial hypertrophy
What are examples of irreversible structural changes?
- hyaline arteriolosclerosis
- arterial fibroelastic intimal hyperplasia
What are the histologic features of normal small artery?
What are the histological features of fibrinoid necrosis?
Destructive changes in malignant HTN
Loss of nuclei
Presence of fibrin
What are the histological features of hyperplastic intimal arteriolitis?
Destructive change in malignant HTN
Concentric proliferation of SMCs
ONION SKINNING!
What are the histologic features of microangiopathic hemolytic anemia?
Destructive adaptation to malignant HTN
Presence of shistocytes (RBCs that look like bites were taken off them
Caused by force of going through fibrin strands at high pressure
What is the clinical manifestation of benign HTN?
- CHF
- MI
- Stroke
- Chronic renal failure
- Subsequent malignant HTN
What are the effects of benign HTN on cardiac tissue?
i. atheroscelerosis
ii. LV hypertrophy
Can result in angina when demand outstrips supply
Less efficient function of myofibrils
Fibrosis that leads to decreased LV compliance
Impaired diastolic filling and systolic contractility
What are the effects of HTN on renal tissue?
- nephroarteriolosclerosis
i. bilateral symmetrical decrease in renal cortical thickness
ii. granular surface
iii. arteriolar changes (eg intimal hyperplasia)
iv. fibrous replacememnt of glomeruli - chronic renal failure
What are the effects of HTN on cerebral tissue?
- microaneurysms (Charcot-Bouchard)
- ischemic infarction
- rupture of Berry aneurysm
What are the gross features of LV hypertrophy?
Concentric due to increased workload
What are the histologic characteristics of hyaline arteriolosclerosis with glomerular sclerosis and tubular atrophy due to HTN?
Loss of nuclei in glomeruli
Atrophic tubules
Hyaline arteriosclerosis present
What are the key characteristics of nephroarteriolosclerosis?
It is a microvascular disease with glomerular scarring and tubular atrophy
-leads to chronic renal failure
Aggravates HTN by
i. decreased GFR and increased Na excretion
ii. activation of RAAS
iii. loss of urodilatin