Hypertension Definition: the force exerted by the blood against the walls of the bleed vessels Adequate to maintain tissue perfusion during activity and rest Arterial blood pressure: primary function of cardiac output and systemic vascular resistance

What is the effect on BP if SVR increased and CO remains constant? Hypertension Arterial BP = Cardiac Output (CO) x Systemic vascular resistance (SVR) Cardiac Output = stroke volume x beats per min Systemic vascular resistance = force opposing the movement of blood within the blood vessels What is the effect on BP if SVR increased and CO remains constant?

Hypertension Mechanisms that Regulate BP Sympathetic Nervous System Vascular Endothelium Renal System Endocrine System

Hypertension Mechanisms that Regulate BP Sympathetic Nervous System (SNS) – norepinephrine released from sympathetic nerve endings - to receptors alpha1, alpha2, beta 1 & beta2 Reacts within seconds Increases Heart Rate - chronotropic Increased cardiac contractility - inotropic Produces widespread vasoconstriction in peripheral arterioles Promotes release of renin from the kidney

Hypertension SNS Receptors Influencing B/P

Hypertension Mechanisms that Regulate BP Sympathetic Nervous System (SNS)– Sympathetic Vasomotor Center – located in the medulla – interacts with many areas of the brain to maintain BP within normal range under various conditions Exercise – changes to meet oxygen demand Postural Changes – peripheral vasoconstriction

Hypertension Mechanisms that Regulate BP Sympathetic Nervous System (SNS) – Baroreceptors: specialized nerve cells the carotid arteries and the aortic arch Sensitive to BP changes: Increase: Inhibits SNS – peripheral vessel dilation. Decreased heart rate, and decreased contractility of the heart + increased parasympathetic activity (vagus nerve) decreased heart rate Decrease: Activates SNS – peripheral vessel constriction, increased heart rate, and increased contractility of the heart

Hypertension Mechanisms that Regulate BP Vascular Endothelium Single cell layer that lines the blood vessels Produce vasoactive substances: EDRF Endothelium-derive relaxing factor – Helps maintain low arterial tone at rest Inhibits growth of the smooth muscle layer Inhibits platelet aggregation Vasodilation – prostacyclin Endothelin (ET) potent vasoconstrictor Endothelial dysfunction may contribute to atherosclerosis & primary hypertension

Hypertension Mechanisms that Regulate BP Renal System Control Na+ excretion & extracellular fluid volume Renal - Renin-angiotensin-aldosterone Renin converts angiotensinogen to angiotensin I Angiotensin-converting enzyme (ACE) converts I into angiotsensin II Immediate: Vasoconstrictor – increased systemic vascular resistance Prolonged: Stimulates the adrenal cortex to secret Aldosterone – Na+ and Water retention Renal Medulla - Prostaglandins - vasodilator effect

Hypertension Renin-Angiotensin

Hypertension Renin-Angiotensin System

Hypertension Mechanisms that Regulate BP Endocrine System Stimulates the SNS with Epinephrine – increases HR and contractility Activates B2-adrenergic receptors in peripheral arterioles of skeletal muscle = vasodilation Activates A1-adrenergic receptors in peripheral arterioles of skin and kidneys = vasoconstiction Adrenal Cortex – Aldosterone – stimulates kidneys to retain Na+ Increased Na+ stimulates posterior pituitary – ADH – reabsorbs ECF/water

Hypertension Aldosterone Mechanism Increased Aldosterone = Increases sodium reabsorption = Increases water reabsorption = Increases blood volume = Increases cardiac output

Hypertension Mechanisms that Regulate BP Regulatory mechanisms in the health person function in response to the demands on the body When Hypertension develops, one or more of these mechanisms are defective Sympathetic Nervous System Vascular Endothelium Renal System Endocrine System

Secondary Hypertension Pathophysiology Specific cause of hypertension can be identified 5+% of adult hypertension Causes: Coarctation or congenital narrowing of the aorta Renal disease – renal artery disease / parenchymal Endocrine disorders: Pheochromocytoma, Cushing Syndrome, Hyperaldosteronism Neurology disorders – brain tumors / head injury Sleep apnea Medications – sympathetic stimulants Pregnancy-induced hypertension

Hypertension Pathophysiology Primary (Essential) Hypertension: Elevated BP without an identified cause Accounts for 95% of all cases of hypertension Cause – unknown Contributing Factors: Increased SNS activity, overproduction of Na+ retaining hormones & vasoconstrictors, increased Na+ intake Risk Factors: Modifiable

Primary Hypertension Pathophysiology Heredity – interaction of genetic, environmental, and demographic factors Water & Sodium Retention – 20% of pts with high Na+ diet develop HTN Altered Renin-Angiotensin Mechanism – found in 20% of patients Stress & Increased SNS Activity Insulin Resistance & Hyperinsulinemia Endothelial Cell Dysfunction

Hypertension Clinical Manifestation Dx is made after multiple readings over several weeks NIH/Joint Committee Definition: Category Systolic Diastolic Optimal <110 and < 80 Normal <120 and <85 High Normal 130-139 or 85-89 Stage 1 140-159 or 90-99 Stage 2 160-179 or 100-109 Stage 3 =>180 or => 110

Primary Hypertension Risk Factors Age Alcohol Cigarette Smoking Diabetes Mellitus Elevated serum lipids Excess Na+ in diet Gender Family History Obesity Ethnicity Sedentary Lifestyle Socioeconomic Stress

Primary Hypertension Clinical Manifestations Target Organ Complications: Myocardium – angina / left ventricular hypertrophy Brain – TIA / CVA Peripheral vascular – Peripheral pulse change Kidney – renal failure Creatinine / Proteinuria Eyes – Hemorrhages with or without papilledema

Primary Hypertension Clinical Manifestations “Silent Killer” – asymptomatic and insidious Severe HTN – fatigue, reduced activity tolerance, dyspnea, dizziness, palpitations, angina

Hypertension Medical Diagnosis History and Physical Examination Renal Function Serum Creatinine & Urine Creatinine Clearance Electrolytes – especially K+ Blood Glucose Serum Lipids/EKG Ambulatory BP Monitoring

Primary Hypertension Medical Management Risk Stratification Level of BP Presence of Target Organ Disease Other Risk Factors

Hypertension Medical Management Risk Stratification

Primary Hypertension Medical Management Lifestyle modification Nutritional therapy Alcohol consumption Physical activity Tobacco avoidance Stress management Drug Therapy

Hypertension Nutrition

Hypertension Risk Factor Modification

Primary Hypertension Medical Management Stepped Approach Lifestyle modification Not at Goal BP Drug Therapy Substitute med / add a 2nd med/ increase dose Continue adding / changing meds until control

Primary Hypertension Medical Management – Drug Therapy Diuretics Thiazide Loop K+ Sparing Adrenergic Blockers/ Inhibitors B-Adrenergic Blockers Central Acting Adrenergic Antagonists Peripheral Acting Adrenergic Antagonists A-Adrenergic Blockers Vasodilators Angiotensin Inhibitors Calcium Channel Blockers

Hypertension Medication - Diuretics

Hypertension Medication – Beta-blocking Agents

Hypertension Medication Calcium Channel Blockers

Hypertension Medication Alpha Agonists & Vasodilators

Hypertension Antihypertensive Drug Therapy

Primary Hypertension Lack of Responsiveness to Therapy Nonadherence to Therapy Drug-Related Causes Associated conditions Secondary Hypertension Volume overload

Primary Hypertension Hypertensive Crisis Definition: Severe & abrupt elevation of BP with diastolic > 120-130mm Hg. Causes: Nonadherence, renovascular changes, pre- eclampsia, eclampsia, Pheochromocytoma, Rebound from abruptly stopping beta blockers, head injury, necrotizing vasculitis, acute aortic dissection Hypertensive Encephalopathy: headache, N/V, confusion, obtunded, stuporous, seizures, blurred vision, transient blindness

Primary Hypertension Nursing Diagnoses Assess: Cardiovascular status; adherence to therapy; family interaction; risk factor modification? Nsg Action: Supportive & reality-based; Administer meds; referrals; diagnostic preps; ask questions; supportive care during hospitalization for acute crisis Pt/Family Education: Medications; risk factor modification; Community support

Hypertension Dynamics of Treatment

Primary Hypertension Case Study