Archive for the ‘ L2-Patho HPT ’ Category

L2- Pathology of Hypertension

Hypertension

It is persistent elevation of blood pressure above 140/90

-It may be primary (essential) or secondary.

– Each type may be benign or malignant (according to severity).

– Each type can affect many organs the most important of which are…heart, blood vessels, kidney, brain and retina

Secondary hypertension

Secondary to….
1- Renal…renal ischemia.

2- Endocrine… hyperaldosteronism, pheochromocytoma, hyperthyroidism.

3- Neurogenic.. Brain tumors or encephalitis.

4- Coarctation of the aorta.

5- Stress, psychogenic, post-operative.

Primary (Essential) hypertension

It is hypertension of unknown etiology but there are certain predisposing factors

a. Familial predisposition.

b. High salt intake

c. Cigarette smoking, alcoholism.

d. Emotional stress.

E. Lack of exercise.

Pathogenesis of hypertension

MEAN ARTERIAL BLOOD PRESSURE

= CARDIAC OUTPUT X TOTAL PERIPHERAL RESISTANCE

BP= C.O  X TPR

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Effects of hypertension

Heart changes.

Vascular changes

Renal changes.

Brain changes.

Retinal lesions.

Causes of death ???

I- Benign Hypertension

1) Heart Changes

-With increasing pressure, the left ventricular myocardium undergoes hypertrophy.

– With hypertension, the severity of atheromatous lesions are usually more severe.

– Coronary blood flow may be insufficient leading to ischemic heart diseases

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Left ventricular hypertrophy

Left ventricular failure is a common complication of hypertension

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2) vascular changes

1- Aorta

– Hypertension predisposes to development of severe atheroma, abdominal aortic aneurysms and dissection.

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Aortic aneurysm

– Atherosclerotic aortic aneurysm affecting the abdominal aorta.

– This aneurysm is complicated by a thrombus.

– Other complications include rupture and pressure on other structures.

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2- Small Blood vessel changes

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Benign arteriolosclerosis

Benign arteriosclerosis

Atheroma is severe

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hyalinosis and elastosis

Both changes below lead to narrowing of the blood vessels and ischemia of the affected parts   and also increased peripheral resistance.

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Hyalinosis

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Elastosis

3) Renal changes

– Arteriolosclerosis leads to progressive ischemia of the nephron, with eventual destruction of glomeruli and atrophy of the tubular system.

– When hypertension has produced significant nephron ischemia and fibrosis, the kidney is said to have developed benign hypertensive nephrosclerosis (primary contracted kidney).

– Renal ischemia  and fibrosis will result in activation of the renin-angiotensin system with further elevation of the blood pressure

– When sufficient nephrons become non functioning, the patient develops progressive chronic renal failure.

– This is a common and important cause of chronic renal failure in the middle-aged and elderly population.

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1-Hyalinosis and elastosis of afferent and efferent arterioles ….. Ischemic necrosis of glomeruli and related nephron….. Fibrosis…..contraction.

2- Compensatory hypertrophy of other nephrons.
1+2 are called primary contracted kidney

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II- Malignant hypertension

– It is elevation of the blood pressure suddenly up to 200/110.

– Course is short for months (unless on top of benign hypertension)

– It produces lesions different from benign hypertension.

1) Vascular changes

Cellular proliferation

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necrotizing arteriolitis

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Necrosis of small blood vessels with increased pressure leads to small focal hemorrhages

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4) Brain Affection

– Hypertensives are particularly prone to develop massive intracerebral hemorrhage due to rupture of intracerebral blood vessels.

– Small vessel damage within the cerebral hemispheres produces micro-infarcts in the form of small areas of brain destruction filled with fluid (hypertensive lacunae).

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Cerebral hemorrhage

5) Retinal changes

– Affection of the retinal blood vessels leads to….
1- Retinal edema and exudates.
2- Retinal hemorrhage.

Causes of death in hypertension

1- Heart failure
2- Cerebral strokes
3- Chronic renal failure.

CLINICAL MANFESTATIOS OF SYSTEMIC ARTERIAL HYPERTENSION

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FIGURE 37-2 Computer printout of blood pressure readings obtained by ambulatory blood pressure monitoring over a 24-hour period beginning at 9 <span class=”sc” >AM.

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FIGURE 37-4 Age-adjusted cardiovascular disease mortality rate by systolic and diastolic blood pressure level used to define each JNC-VI stratum among the men aged 45 to 57 years enrolled in the Multiple Risk Factor Intervention Trial from 1973 to 1975 and followed through 1996. (Modified from Domanski M, Mitchell G, Pfeffer M, et al: Pulse pressure and cardiovascular disease-related mortality. JAMA 287:268, 2002.)

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PREVALENCE

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FIGURE 37-1 International Society of Hypertension prevalence of hypertension among three populations, ages 35 to 74 years: InterASIA (2000–2001), the Egyptian National Hypertension Project (1991–1993), and the Third National Health and Nutrition Examination Survey (1989–1994). (From Gu D, Reynolds K, Wu X, et al: Prevalence, awareness, treatment, and control of hypertension in China. Hypertension 40:925, 2002.)

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FIGURE 37-6 Prevalence of high blood pressure by age and race or ethnicity for men and women 18 years and older in the U.S. population. Data bars marked with an asterisk are based on a sample size that did not meet the minimum requirements of the National Health and Nutrition Examination Survey (NHANES) III design or relative SEM greater than 30 percent. (Data from Burt VL, Whelton P, Roccella EJ, et al: Prevalence of hypertension in the US adult population: Results from the Third National Health and Nutrition Examination Survey 1988–91. Hypertension 25:305, 1995.)

CLINICAL EVALUATION OF HYPERTENSIVE PATIENT

GOALS

BLOOD PRESSUE MEASURMENT

SECONDARY CAUSES OF HYPERTENSION

TARGET ORGAN DAMAGE

OTHER CARDIVASCULAR RISF FACTORS

BLOOD PRESSURE MEASUREMENT

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TABLE 37-2 Guidelines in Measuring Blood Pressure

SECONDARY CAUSES OF HYPERTENSION AND OTHER CARDIOVASCULAR RISK FACTORS

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TABLE 37-7 Overall Guide to Work-up for Identifiable Causes of Hypertension

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TABLE 37-12 Clinical Clues for Renovascular Hypertension

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TABLE 37-14 Syndromes of Mineralocorticoid Excess

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TABLE 37-15 Features Suggestive of Pheochromocytoma

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HYPERTENSIVE CRISIS

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TABLE 37-18 Circumstances Requiring Rapid Treatment of Hypertension

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TABLE 37-19 Clinical Characteristics of Hypertensive Crisis