Hypertension Hypertension Definition: Definition: the force exerted by the force exerted by the blood against the walls of the the blood against the walls of the bleed vessels bleed vessels Adequate to maintain tissue perfusion Adequate to maintain tissue perfusion during activity and rest during activity and rest Arterial blood pressure: primary Arterial blood pressure: primary function of cardiac output and function of cardiac output and systemic vascular resistance systemic vascular resistance
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Hypertension Definition: the force exerted by the blood against the walls of the bleed vessels Adequate to maintain tissue perfusion during activity.
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HypertensionHypertension
Definition:Definition: the force exerted by the the force exerted by the blood against the walls of the bleed blood against the walls of the bleed vessels vessels
Adequate to maintain tissue perfusion Adequate to maintain tissue perfusion during activity and restduring activity and rest
Arterial blood pressure: primary Arterial blood pressure: primary function of cardiac output and function of cardiac output and systemic vascular resistancesystemic vascular resistance
HypertensionHypertension
Arterial BP = Cardiac Output (CO) x Arterial BP = Cardiac Output (CO) x Systemic Systemic vascular resistance vascular resistance (SVR)(SVR)
Cardiac OutputCardiac Output = stroke volume x beats per min = stroke volume x beats per min
Systemic vascular resistanceSystemic vascular resistance = force opposing = force opposing the movement of blood within the blood vesselsthe movement of blood within the blood vessels
What is the effect on BP if SVR increased What is the effect on BP if SVR increased and CO remains constant?and CO remains constant?
HypertensionHypertension Mechanisms that Regulate Mechanisms that Regulate
HypertensionHypertensionMechanisms that Regulate Mechanisms that Regulate
BPBPSympathetic Nervous System (SNS)Sympathetic Nervous System (SNS) – – norepinephrine released from norepinephrine released from sympathetic nerve endings - to receptors sympathetic nerve endings - to receptors alpha1, alpha2, beta 1 & beta2alpha1, alpha2, beta 1 & beta2
HypertensionHypertensionMechanisms that Regulate Mechanisms that Regulate
BPBPSympathetic Nervous System (SNS)Sympathetic Nervous System (SNS)––
Sympathetic Vasomotor Center – located Sympathetic Vasomotor Center – located in the medulla – interacts with many areas in the medulla – interacts with many areas of the brain to maintain BP within normal of the brain to maintain BP within normal range under various conditionsrange under various conditions
HypertensionHypertensionMechanisms that Regulate Mechanisms that Regulate
BPBPSympathetic Nervous Sympathetic Nervous System (SNS)System (SNS) – –
BaroreceptorsBaroreceptors: specialized nerve cells : specialized nerve cells the carotid arteries and the aortic archthe carotid arteries and the aortic arch
Sensitive to BP changes:Sensitive to BP changes:Increase: Inhibits SNSIncrease: Inhibits SNS – peripheral vessel – peripheral vessel
dilation. Decreased heart rate, and dilation. Decreased heart rate, and decreased contractility of the heart + decreased contractility of the heart + increased parasympathetic activity (vagus increased parasympathetic activity (vagus nerve) decreased heart ratenerve) decreased heart rate
Decrease: Activates SNSDecrease: Activates SNS – peripheral – peripheral vessel constriction, increased heart rate, vessel constriction, increased heart rate, and increased contractility of the heartand increased contractility of the heart
HypertensionHypertension Mechanisms that Regulate Mechanisms that Regulate
BPBPVascular EndotheliumVascular Endothelium
Single cell layer that lines the blood vesselsSingle cell layer that lines the blood vesselsProduce vasoactive substancesProduce vasoactive substances::
EDRF Endothelium-derive relaxing factorEDRF Endothelium-derive relaxing factor – – Helps maintain low arterial tone at restHelps maintain low arterial tone at rest Inhibits growth of the smooth muscle layerInhibits growth of the smooth muscle layer Inhibits platelet aggregationInhibits platelet aggregation
Renin converts angiotensinogen to Renin converts angiotensinogen to angiotensin Iangiotensin I
Angiotensin-converting enzyme (ACE) Angiotensin-converting enzyme (ACE) converts I into angiotsensin II converts I into angiotsensin II Immediate: Vasoconstrictor – increased Immediate: Vasoconstrictor – increased
systemic vascular resistancesystemic vascular resistanceProlonged: Stimulates the adrenal cortex Prolonged: Stimulates the adrenal cortex
to secret Aldosterone – Na+ and Water to secret Aldosterone – Na+ and Water retentionretention
HypertensionHypertensionRenin-Angiotensin SystemRenin-Angiotensin System
HypertensionHypertensionMechanisms that Regulate Mechanisms that Regulate
BPBPEndocrine System Endocrine System
Stimulates the SNS with Stimulates the SNS with Epinephrine – increases HR and contractilityEpinephrine – increases HR and contractilityActivates B2-adrenergic receptors in peripheral Activates B2-adrenergic receptors in peripheral
arterioles of skeletal muscle = vasodilation arterioles of skeletal muscle = vasodilation Activates A1-adrenergic receptors in peripheral Activates A1-adrenergic receptors in peripheral
arterioles of skin and kidneys = arterioles of skin and kidneys = vasoconstictionvasoconstiction
Adrenal Cortex – Aldosterone – stimulates Adrenal Cortex – Aldosterone – stimulates kidneys to retain Na+kidneys to retain Na+
Specific cause of hypertension can be Specific cause of hypertension can be identifiedidentified
5+% of adult hypertension5+% of adult hypertension Causes:Causes:
Coarctation or congenital narrowing of the aortaCoarctation or congenital narrowing of the aorta Renal disease – renal artery disease / Renal disease – renal artery disease /
Creatinine ClearanceCreatinine ClearanceElectrolytes – especially K+Electrolytes – especially K+Blood Glucose Blood Glucose Serum Lipids/EKGSerum Lipids/EKGAmbulatory BP MonitoringAmbulatory BP Monitoring
Assess:Assess: Cardiovascular status; adherence to Cardiovascular status; adherence to therapy; family interaction; risk factor therapy; family interaction; risk factor modification?modification?
supportive care during hospitalization for supportive care during hospitalization for acute crisisacute crisis
Pt/Family Education: Pt/Family Education: Medications; risk factor Medications; risk factor modification; Community supportmodification; Community support
HypertensionHypertensionDynamics of TreatmentDynamics of Treatment
Primary HypertensionPrimary HypertensionCase StudyCase Study