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A Quick Literature Review Presentation on: Hypertension

Presentation · January 2012

DOI: 10.13140/RG.2.1.3450.5361

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College of Health Sciences Department of Medical Physiology Advanced Cardiovascular Physiology Presentation on Hypertension By Teketel Eristu

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Presentation Outline

• Introduction
• Blood Pressure
• High Blood Pressure/Hypertension
• Causes of Hypertension/Risk Factors
• Types of Hypertension
• Regulation of HBP/HPN
• Prevention and Treatment of HPN
• Animation of HPN, Video
• References

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Objectives

At the end of the Presentation the Learners are expected to: Discuss about Blood Pressure Explain High Blood Pressure/ Hypertension in detail Classify Hypertension and Causes Explain the Consequences of Hypertension Discuss the regulation of Hypertension Explain Treatment of Hypertension

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• 1. Introduction

Blood Pressure

• is the pressure exerted by circulating blood upon the walls of blood

Vessels

• decreases as the circulating blood moves away from the heart
• expressed in terms of the systolic pressure over diastolic pressure

(mmHg). Or it makes Lup Dup major sound

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Lub

If you listen to your heartbeat, it makes a lub dub sound. The lub is when blood is pushed out of the heart into the body and the dub is the reloading of the heart with more blood ready to push it

• ut to the body

Dub

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Cont..

Blood pressure is an important characteristic of our body. Without blood pressure, nutrients, oxygen, and proteins could not travel from the arterial side of the body to the venous side.

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Cont… Normal Blood Pressure 95/65 mmHg=1 Years 100/65 mmHg=6-9 years 110/65-140/90mmHg= Adults

• its Average Physiologic Value (normal BP) = 120/80 mmHg

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Cont… If blood pressure is chronically elevated a condition is known as hypertension According to medical dictionary, hypertension means "High blood pressure; transitory or sustained elevation of systemic arterial blood pressure A consistent blood pressure of 140/90 mm Hg or higher is considered high blood pressure.

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Cont…

• Isolated Systolic Hypertension is Systolic BP elevation in the absence
• f elevated diastolic Blood Pressure .
• Isolated Diastolic Blood Pressure is Diastolic BP elevation in the

absence of Systolic BP.

• Accelerated Hypertension / Malignant Hypertension occurs when BP

elevates extremely .

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Table.1. Classification of Blood Pressure for Adults =>18 Years old

Category Systolic mmHg Diastolic mmHg Hypotension <90 <60 Desirable/Normal 90-119 60-79 Prehypertension 120-139 80-89 Stage 1/Mild Hypertension 140-159 90-99 Stage 2 / Moderate Hypertension 160-179 100-109 Hypertensive Crisis/ stage 3/ Severe/HYN => 180 =>110 Isolated Systolic HYN =>140 <90

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• 2. Types of Hypertension

is abnormal elevation of pulmonary artery BP.

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Cont…

• Pulmonary blood pressure is normally a lot lower than systemic blood

pressure.

• Normal pulmonary-artery pressure is about 14 mm Hg at rest.
• If the pressure in the pulmonary artery is greater than 25 mm Hg at

rest and 30 mm Hg during exercise, it is abnormally high and is called pulmonary hypertension.

• Broadly Classified as Primary or Secondary Hypertension

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Cont…

• Primary pulmonary hypertension
• When not accompanied by underlying heart and

lung disease or other illnesses, it is called primary pulmonary hypertension.

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Con…. Secondary pulmonary hypertension If a pre-existing disease triggered the PHT e.g. Congenital heart defects Intracardiac left-to-right shunts : Heart valve conditions : mitral stenosis

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Cont….

• Typically "blood pressure," "high blood pressure" and "hypertension"

refer to the systemic pressure throughout your body. Hypertension is classified as either primary (essential) Idiopathic / hypertension or secondary hypertension

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a) Primary or Essential Hypertension

About 90–95% of cases are categorized as "primary hypertension," which means high blood pressure with no

• bvious/direct medical cause.
• is the most prevalent hypertension type

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Cont..

Although no direct cause has been identified, there are many factors such as sedentary lifestyle, smoking, stress, visceral obesity,, salt (sodium) sensitivity, alcohol intake, and vitamin D deficiency, aging, some inherited genetic mutations and having a family history of hypertension, an elevated level of renin, sympathetic nervous system

• ver activity…etc. increase the risk of developing primary

hypertension.

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b) Secondary Hypertension About 5–10% of cases (Secondary hypertension) are caused by other conditions that affect the kidneys, arteries, heart or endocrine system. Thus, results from an identifiable cause. but: may come to normal values by treatment.

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Cont…

This type is important to recognize since it's treated differently to essential

• hypertension. Facrors that cause this type of HYN

1. Adrenocortical hyperfunction Primary hyperaldosteronism Cushing Syndrome Congenital or hereditary adrenogenital syndromes (17a-hydroxylase and 11b-hydroxylase defects)

• 2. Pheochromocytoma
• 3. Severe Polycythemia

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Cont…

4). Renal Diseases

It is common for all types of chronic kidney disease to eventually cause hypertension (approx. 80% of chronic kidney disease patients develop hypertension at some point). This is due to fluid retention in the body, due to poor elimination of fluids and poor control of sodium

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Cont…. Glomerulonephritis (chronic renal inflammation ) Polycystic renal disease-is cystic genetic disorder of the kidneys Tumors of JG Cell- Renin-producing tumors Renovascular stenosis or renal infarction (Reno vascular hypertension)------RAS Hyperparathyroidism and Calcium overload leads to renal failure and hypertension

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Cont…

5) Neurogenic hypertension

Polyneuritis ( lead poisoning…..) inflammation of Peripheral nerves Increased intracranial pressure Arterial occlusion Tumors

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Cont…. Others

Coarctation of aorta  BP in upper parts of body, i.e. above

• bstruction.

Hypercalcemia Medications, e.g., glucocorticoids, …etc

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Consequences of Hypertension: Organ Damage

CHF=congestive heart failure; CHD=coronary heart disease; LVH=left ventricular hypertrophy.

Chobanian AV et al. JAMA. 2003;289:2560-2572.

Hypertension Hypertension LVH, CHD, CHF LVH, CHD, CHF Chronic kidney disease Retinopathy Retinopathy Transient ischemic attack, stroke Peripheral arterial disease

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Regulation of HBP/HPN Introduction: Blood Pressure is regulated within a narrow Range If the blood pressure is too low: Inadequate perfusion of organs If the Blood pressure is abnormally high: Heart diseases, Vascular diseases ,strokes….

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Cont… The Baroreceptor reflex functions to restore blood pressure back to normal values whenever the blood pressure deviates from the normal range. The homeostatic mechanism involves a negative feedback loop to minimize and oppose any changes in Blood pressure. i.e. An increase in BP reflexively causes the BP to decrease and vice versa.

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What is a Baroreceptor?

Stretch –sensitive Mechanoreceptors Located in the Carotid Sinus and aortic arch Monitor the pressure of blood flow to brain and body Action potentials are fired continuously at normal blood pressure

• Fig. 1 Location and innervations of arterial Baroreceptor

High pressure baroreceptors respond to stretch in the aortic arch and carotid sinus.

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Pathway

Increase in BP stretches the baroreceptors and increase the firing rate in the afferent nerves Glossopharyngeal nerve and Vagus nerve This leads to the excitation of the nucleus tractus solitarius(NTS) in the Medulla, which inturn inhibits the vasomotor center via interneurones.

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Cont…

The inhibition of the vasomotor center decrease the sympathetic output and causes vasodilation, bradycardia, decrease in CO & fall in BP The excitation of NTS also stimulates the Vagus nerve which decrease the HR & CO

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Baroceptors with increased P Medulla Heart and Blood Vessels

Nucleus tractus solitarius Cardiac decelerator Cardiac accelerator Cardiac accelerator Vaso constrictor Sinoatrial node Sinoatrial node Contract- ility Contract- ility Arterioles Arterioles Veins Veins

Carotid sinus baroceptors Aortic arch baroceptors

Vagus nerve Vagus nerve Carotid sinus nerve glossopharyngeal nerve Carotid sinus nerve glossopharyngeal nerve

Heart Blood vessels

+ + +

• Dilation
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Blood Pressure Regulation

Baroreceptors Afferent nerves Medulla oblongata center Sympathetic efferents SA node, ventricles, Arteriolar smooth muscle Venous smooth muscle

Fig 2 Components of the Baroreceptor Reflex

• Main coordinating center is in the

medulla oblongata of the brain; medullary cardiovascular control center

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Regulation of Blood Pressure

Figure 3 T he baroreceptor reflex: the response to increased blood pressure

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Fig.4 Blood Pressure control includes rapid responses from cardiovascular system and slower responses by the kidneys When the body contains too much EC fluid, the arterial pressure rises. This increase in pressure causes the kidneys to excrete the excess fluid, until pressure returns to normal (pressure diuresis).

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5.Prevention and Treatment of Hypertension ACE Inhibitors Drugs inhibit the enzyme converting angiotensin into angiotensin II. Acts as vasodilators of both resistance and capacitance

• vessels. Thus, blood vessels relax and blood flow freely.

Angiotensin II receptor blockers

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Cont….

Diuretics work on the kidney to remove exess water and fluid from body to lower BP. Beta blockers-: Competitively inhibit the binding of catecholamines to beta-adrenergic receptors Calcium Channel Blockers- Decrease calcium influx into cells of vascular smooth muscle -causes the blood vessel to relax and widen. Nervous system inhibitors- slow nerve impulses to the heart. Vasodilators- cause blood vessel to widen, allowing blood to flow more freely. Alpha Blocker- blocks an impulse to the heart causing blood to flow more freely.

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Cont….

Minimize Alcohol Alcohol raises blood pressure and can harm liver, brain, and heart

• Quite Smoking/ Stop
• Smoking damages blood vessel walls and causes early hardening of

the arteries. Nicotine narrows your blood vessels and forces your heart to work harder Be Physically Active/Exercise Blood pressure rises as weight rises. Obesity is also a risk factor for heart disease

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• 5. References
• 1. Fauci, Braundwald, Kasper and et al, Harrison’s principles of internal

medicine, 17th edition, 2008, McGraw Hill publisher 2.Pearson International Edition Human Physiology An Integrated Approach 5th Edition. DEE UNGLAUB SILVERTON 3 .ww.americanheart.org/presenter.jhtml?identifier “High Blood Pressure” 4.Different internet sources

• 5. Lecture Note of Cardiovascular Physiology, Prof. Yekoya A. 2011

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THANK YOU

teketel.eristu@amu.edu.et

THANK YOU

teketel.eristu@amu.edu.et

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