peripheral vascular resistance

peripheral vascular resistance,

a resistance to the flow of blood determined by the tone of the vascular musculature and the diameter of the blood vessels. It is responsible for blood pressure when coupled with stroke volume.

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hypertension

High blood pressure Cardiovascular disease An abnormal ↑ systemic arterial pressure, corresponding to a systolic BP of > 160 mm Hg and/or diastolic BP of 95 mm Hg and graded according to intensity of ↑ diastolic BP; HTN affects ± 60 million in the US Workup Evaluation of HTN requires clinical Hx for Pt, family Hx, 2 BP determinations, funduscopy, ID of bruits in neck & abdominal aorta, evaluation of peripheral edema, peripheral pulses and residual neurologic defects in stroke victims, chest films to determine cardiac size and lab parameters to rule out causes of secondary HTN Risk factors Race–blacks more common, ♂, family history of HTN, obesity, defects of lipid metabolism, DM, sedentary lifestyle, cigarette smoking, electrolyte imbalance–eg, ↑ sodium, phosphorus, ↓ potassium, tin Treatment Diet–eg, sodium restriction, ↓ calories, alcohol and cigarettes–the weight gain accompanying smoking cessation tends to offset the minimal ↓ in BP, calcium supplements, lifestyle manipulation–eg, biofeedback, ↑ exercise; antihypertensives–eg, diuretics–benzothiadiazines, loop diuretics, potassium-sparing diuretics, sympatholytic agents–central and peripheral-acting α-adrenergics, β-adrenergics, mixed α- and β-blockers, direct vasodilators, ACE inhibitors–the preferred agent to use ab initio, dihydropiridine CCBs. See ACCT, ACE inhibitor, Borderline hypertension, Borderline isolated systolic hypertension, Calcium channel blocker, Drug-induced hypertension, Essential hypertension, Exercise hypertension, Familial dyslipemic hypertension, Gestational hypertension, Idiopathic intracranial hypertension, Isolated systolic hypertension, Malignant hypertension, MRC, Obetension, Paradoxic hypertension, Pill hypertension, Pregnancy-induced hypertension, Pseudohypertension, Pulmonary hypertension, Refractory hypertension, Renovascular hypertension, SHEP, STOP-Hypertension, TAIM, TOHP-1, TOMHSTyramine hypertension, White coat hypertension.

Hypertension

Class I–mild Diastolic pressure 90-104 mm Hg

Class II–moderate Diastolic pressure 105-119 mm Hg

Class III–severe Diastolic pressure > than 120 mm Hg

Hypertension types

Essential hypertension Idiopathic HTN The major form comprising 90% of all HTN

Malignant hypertension A sustained BP > 200/140 mm Hg, resulting in arteriolar necrosis, most marked in the brain, eg. cerebral hemorrhage, infarcts, and hypertensive encephalopathy, eyes, eg papilledema and hypertensive retinopathy and kidneys, eg acute renal failure and hypertensive nephropathy; if malignant HTN is uncorrected or therapy refractory, Pts may suffer a hypertensive crisis in which prolonged high BP causes left ventricular hypertrophy and CHF

Paroxysmal hypertension Transient or episodic waves of ↑ BP of any etiology, punctuated by periods of normotension, typical of pheochromocytoma

Portal hypertension ↑ portal vein pressure caused by a backflow of blood through splenic arteries, resulting in splenomegaly and collateral circulation, resulting in esophageal varices and/or hemorrhoids; PH may be intra- or extrahepatic, and is often due to cirrhosis, or rarely portal vein disease, venous thrombosis, tumors or abscesses

Pulmonary hypertension A condition defined as a 'wedge' systolic/diastolic pressure > 30/20 mm Hg–Normal: 18-25/12-16 mm Hg, often secondary to blood stasis in peripheral circulation, divided into passive, hyperkinetic, vasoocclusive, vasoconstrictive and secondary forms. See Pulmonary HTN.

Renovascular hypertension see there

Secondary hypertension

• Aging

• Cardiovascular Open heart surgery, coarctation of aorta, ↑ cardiac output–anemia, thyrotoxicosis, aortic valve insufficiency

• Cerebral ↑ Intracranial pressure

• Endocrine Mineralocorticoid excess, congenital adrenal hyperplasia, glucocorticoid excess, eg Cushing syndrome, hyperparathyroidism, acromegaly

• Gynecologic Pregnancy, oral contraceptives

• Neoplasia Renin-secreting tumors, pheochromocytoma

• ↓ Peripheral vascular resistance AV shunts, Paget's disease of bone, beri-beri

• Renal disease Vascular, parenchymal