vipul heart

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GOOD MORNINGGOOD MORNING


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CARDIAC CYCLE&

HEART SOUNDS


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CONTENTS

Introduction Cardiovascular System Path and Blood Supply to Heart

Blood Vessels, Pulse and Blood Pressure Electrocardiogram Heart Sounds Cardiac Cycle

Age related changes Conclusion References


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INTRODUCTION

Cardiovascular system comprises ofHeart and Blood Vessels. Heart is thecentral pump and the blood vessels are

the series of distributing and collectingtubes. The function of cardio vascularsystem is to supply oxygen, nutrientsand other essential substances to the

tissues of the body and to removemetabolic end products from thetissues.


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Every heart beat consists of two major

periods called systole and diastole.

During systole, there is contraction of

the cardiac muscle and pumping of

blood from the heart. During diastole,

there is relaxation of cardiac muscleand filling of blood.

Thus, the cardiac cycle is defined as the

succession of coordinated activities,which take place during every heart

beat.


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The mechanical activities of the heart

during each cardiac cycle, cause theproduction of some sounds, which are

called Heart Sounds.


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Cardio Vascular System


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Size of Heart

Average Size of Heart

14 cm long

9 cm wide


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Location of Heart

posterior to sternum

medial to lungs

anterior to vertebral

columnbase lies beneath 2nd rib

apex at 5th intercostal

space

lies upon diaphragm


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Wall of the Heart


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Wall of the Heart


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Heart Chambers

Right Atrium

receives blood from

inferior vena cava

superior vena cava

coronary sinus

Left Atrium

receives blood from

pulmonary veins

Right Ventricle

receives blood from

right atrium

Left Ventricle

receives blood

from left atrium


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Heart Valves


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Pulmonary and Aortic ValveTricuspid Valve


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Skeleton of Heartfibrous rings to which the heart valves are attached


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Path of Blood Through theHeart


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Blood Supply to Heart


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Angiogram of CoronaryArteries


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Blood Vessels

arteriescarry blood away from ventricles of heart

arterioles

receive blood from arteries

carry blood to capillariescapillaries

sites of exchange of substances between blood and

body cells

venules

receive blood from capillaries

veins

carry blood toward ventricle of heart


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Arteries and Arterioles

Arterythick strong wall

endothelial lining

middle layer ofsmooth muscle and

elastic tissue

outer layer of

connective tissue

carries blood under

relatively high

pressure

Arteriolesthinner walls

endothelial lining

some smoothmuscle tissue

small amount of

connective tissue

helps control

blood flow into a

capillary


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Walls of Artery and Vein


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Arteriolesmallest arterioles only have a few smooth muscle fibers

capillaries lack muscle fibers


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Metarterioleconnects arteriole directly to venule


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Capillaries

smallest diameter blood vessels

extensions of inner lining of

arterioles

walls are endothelium only

semipermeable

sinusoids leaky capillaries


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Capillary Network


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Regulation of CapillaryBlood Flow

Precapillarysphincters

may close a

capillary

respond to needsof

the cells

low oxygen and

nutrients cause

sphincter to relax


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Exchange in theCapillarieswater and other substances leave capillaries because of net outward pressure

at the capillaries arteriolar ends

water enters capillaries venular ends because of a net inward pressure

substances move in and out along the length of the capillaries according to

their respective concentration gradients


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Venules and Veins

Venule

thinner wall than arteriole

less smooth muscle and elastic tissue than arteriole

Vein

thinner wall than artery

three layers to wall but middle layer is poorly developed

some have flaplike valvescarries blood under relatively low pressure

serves as blood reservoir


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Venous Valves


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Characteristics of BloodVessels


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Arterial Blood Pressure

Blood Pressure force the blood exerts against the inner walls of the

blood vessels

Arterial Blood Pressurerises when ventricles contract

falls when ventricles relax

systolic pressure maximum pressure

diastolic pressure minimum


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Pulse

alternate expanding

and recoiling of the

arterial wall that

can be felt


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Factors That InfluenceArterial Blood Pressure


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Control of Blood PressureControlling cardiac output and peripheral resistance regulates blood pressure


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If blood pressure rises, baroreceptors initiatethe cardioinhibitory reflex, which lowers theblood pressure


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Baroreceptors in the Vena Cava signal

cardioaccelerator reflex and sends

sympathetic impulses to the heart.

Baroreceptors in Vena Cava stretchedsend signal to cardiac center sends

sympathetic impulses to the heart

Heart rate increases


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Dilating arterioles helps regulate blood

pressure

(peripheral resistance)


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Venous Blood Flow

not a direct result of heart

action

dependent on

skeletal muscle

contraction

breathing

venoconstriction


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Central Venous Pressure

pressure in the right atrium

factors that influence it alter flow of blood into the

right atrium

affects pressure within the peripheral veins

weakly beating heart increases central venous

pressure

increase in central venous pressure causes blood

to back up into peripheral vein


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Cardiac ConductionSystem


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Electrocardiogram

An Electrocardiogram is a test that uses sound

waves to create a moving picture of the heart


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Benefits Accurate assessment tool that provides useful

information

Helps doctors determine the degree of themurmur, and assess overall health of heart

Drawbacks Time and Cost, ECGs require a substantial

amount of time and resources to perform


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recording of electrical changes that occur

in the myocardium

used to assess hearts ability to conduct

impulses

P wave atrial depolarization

QRS wave ventricular depolarizationT wave ventricular repolarization


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Composite of all action potentials of nodal

and myocardial cells detected, amplified and

recorded by electrodes on arms, legs andchest


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P wave SA node fires, atrial depolarization atrial systole

QRS complex atrial repolarization and diastole (signal obscured) AV node fires, ventricular depolarization ventricular systole

T wave ventricular repolarization


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Normal Electrocardiogram(ECG)


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Electrical Activity ofMyocardium1)atria begin to

depolarize

2) atria depolarize

3)ventricles begin todepolarize at apex;atria repolarize

4)ventricles depolarize

5) ventricles begin to

repolarize at apex6) ventricles repolarize


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Clinical Application

Ventricular fibrillation rapid, uncoordinateddepolarization of ventricles

Tachycardia rapid heartbeat

Atrial flutter rapid rate of atrial

depolarization


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HEART SOUNDS


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General Principles

Contraction of the myocardium generates pressure

changes which result in the orderly movement ofblood.

Blood flows from an area ofhigh pressure to an

area oflow pressure, unless flow is blocked by a

valve. Events on the right and left sides of the heart are the

same, but pressures are lower on the right.


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Heart SoundsLubb

first heart sound occurs during ventricular systole A-V valves closing

Dupp second heart sound occurs during ventricular diastole pulmonary and aortic semilunar valves

closing

Murmur abnormal heart sound


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Auscultation - listening to sounds made by

body

First heart sound (S1), louder and longer

lubb, occurs with closure of AV valves Second heart sound (S2), softer and sharper

dupp occurs with closure of semilunar

valves S3 - rarely heard in people > 30


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A heart which is beating normal makes two

sounds, "lubb" when the valves between the

atria and ventricles close, and "dupp" whenthe valves between the ventricles and the

major arteries close.

Normal Blood Flow

Cardiac chambersCardiac valves


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A heart murmur is an abnormal, extra

sound during the heartbeat cycle made by

blood moving through the heart and itsvalves

Abnormal Blood Flow,

(pulmonary valve stenosis )


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Cardiovascular diagram of anormal heart sound

Lubb-dupp associated with the human heartbeat

C di l Di f E l


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Cardiovascular Diagram of a Earlysystolic murmur

Notice the extra noise in-between the lubb-dupp. This can be attributed to a heart

murmur


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CARDIAC CYCLE


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The cardiac cycle is regulated by the cardiac

center in the medulla oblongata which

regulates sympathetic and parasympa-thetic

input.

M j E t f C di C l


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Major Events of Cardiac Cycle

Atrial systole

Isovolumetric contraction

Ventricular ejection

Isovolumetric relaxation

Ventricular filling


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Atrial Systole/Ventricular Diastole

blood flows passively into ventricles

remaining 30% of blood pushed into ventricles

A-V valves open/semilunar valves close

ventricles relaxed

ventricular pressure increases


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Ventricular Systole/Atrial diastole

A-V valves close

atria relaxed

blood flows into atria

ventricular pressure increases and opens semilunarvalves

blood flows into pulmonary trunk and aorta

R t f C di C l


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Rate of Cardiac Cycle

Atrial systole, 0.1 sec

Ventricular systole, 0.3 sec

Quiescent period, 0.4 sec

Total 0.8 sec, heart rate 75 bpm

Di t l d S t l


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Diastole and Systole

Diastole - the time during which cardiac muscle relaxes.

Systole - the time in which cardiac muscle is contracting.

I - The Heart at Rest : Atrial and Ventricular Diastole While both atria and ventricles are relaxing, the atria begin filing with blood

from the veins while the ventricles have just completed a contraction

As the ventricles relax the AV valves between the atria and ventricles open,

and blood flows from the atria to the ventricles.


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II - Completion of Ventricular Filling : Atrial Systole The last 20% of the filling of the ventricles is accomplished when

the atria contract. Atrial systole begins following depolarization ofthe SA node.

Atrial contraction can aid filling of the ventricles in stenosis of theAV valves.

The force of atrial contraction can also push blood back into thevein. This can be observed by the pulse in jugular vein of anormal person lying w/ the head and chest elevated about 30degrees. If there is an observable jugular pulse higher on the

neck of a person sitting upright, it is indication that the pressurein the atria is higher than normal.

III- Early Ventricular Contraction and the 1st Heart Sound Ventricular Systole begins at the apex of the heart as spiral

bands of muscle squeeze the blood upward toward the base.Blood pushing upward on the underside of the AV valve forcesthem closed so that blood cannot flow back into the atria.

Vibrations following closure of the AV valves creates the 1stheart sound, the lub of lub-dup.


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IV - The heart pumps: Ventricular Ejection As the ventricles contract, they generate enough pressure to open the

semilunar valves and the blood is pushed into the arteries.

The pressure created by ventricular contraction becomes the drivingforce for blood flow.

V - Ventricular Relaxation and the 2nd Heart Sound As the ventricles begin to relax, ventricular pressure decreases.

Once ventricular pressure falls below the pressure in the arteries bloodstarts to flow backward into the heart. This backflow fills the cusps of

the semilunar valves, forcing them together into the closed position.

The vibrations of the semilunar valve closure is the 2nd heart sound, the

dup of lub-dup.

The AV valves open once the pressure in the ventricles falls below the

pressure in the atria and the cycle starts again.

ATRIAL SYSTOLE Heart


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ATRIAL SYSTOLE - Heart

Prior to atrial systole, blood has

been flowing passively from the

atrium into the ventricle through

the open AV valve.

During atrial systole the atriumcontracts and tops off the volume

in the ventricle with only a small

amount of blood. Atrial

contraction is complete before the

ventricle begins to contract.

ATRIAL SYSTOLE


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ATRIAL SYSTOLEPressures & Volumes

The "a" wave occurs when theatrium contracts, increasing atrialpressure (yellow).

Blood arriving at the heart cannotenter the atrium so it flows backup the jugular vein, causing thefirst discernible wave in the

jugular venous pulse. Atrial pressure drops when the

atria stop contracting.

During atrial systole the atriumcontracts and tops off the volumein the ventricle with only a smallamount of blood.

Atrial contraction is completebefore the ventricle begins tocontract.

ATRIAL SYSTOLE


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ATRIAL SYSTOLEECG

An impulse arising from the SA node results in depolarization andcontraction of the atria (the right atrium contracts slightly before theleft atrium).

The P wave is due to this atrial depolarization. The PR segment is electrically quiet as the depolarization proceeds

to the AV node. This brief pause before contraction allows the ventricles to fill

completely with blood.

ATRIAL SYSTOLE


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ATRIAL SYSTOLEHeart Sounds

A fourth heart sound (S4) is abnormal and is associated with the end

of atrial emptying after atrial contraction.

It occurs with hypertrophic congestive heart failure, massive

pulmonary embolism, tricuspid incompetence, or cor pulmonale.


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ISOVOLUMETRIC

CONTRACTION

The Beginningof systole

ISOVOLUMETRIC CONTRACTION


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ISOVOLUMETRIC CONTRACTIONHeart

The atrioventricular (AV) valves

close at the beginning of this

phase.

Electrically, ventricular systole is

defined as the interval betweenthe QRS complex and the end of

the T wave (the Q-T interval).

Mechanically, ventricular systole

is defined as the interval between

the closing of the AV valves andthe opening of the semilunar

valves (aortic and pulmonary

valves).



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ISOVOLUMETRIC CONTRACTIONPressures & Volumes

The AV valves close when the

pressure in the ventricles (red)

exceeds the pressure in the atria

(yellow).

As the ventricles contractisovolumetrically -- their volume

does not change (white) -- the

pressure inside increases,

approaching the pressure in the

aorta and pulmonary arteries(green).



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ISOVOLUMETRIC CONTRACTIONECG

The electrical impulse propagates from the AV node through the His

bundle and Purkinje system to allow the ventricles to contract from

the apex of the heart towards the base.

The QRS complex is due to ventricular depolarization, and it marksthe beginning of ventricular systole. It is so large that it masks the

underlying atrial repolarization signal. the ventricles to fill completely

with blood.



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ISOVOLUMETRIC CONTRACTIONHeart Sounds

The first heart sound (S1, "lub") is due to the closing AV valves and

associated blood turbulence.


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RAPID EJECTION

RAPID EJECTION


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RAPID EJECTIONHeart

The semilunar (aortic and

pulmonary) valves open at the

beginning of this phase.

RAPID EJECTION


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RAPID EJECTIONPressures & Volumes

While the ventricles continue

contracting, the pressure in theventricles (red) exceeds the pressure inthe aorta and pulmonary arteries(green); the semilunar valves open,blood exits the ventricles, and thevolume in the ventricles decreasesrapidly (white).

As more blood enters the arteries,pressure there builds until the flow ofblood reaches a peak.

The "c" wave of atrial pressure is notnormally discernible in the jugularvenous pulse. Right ventricularcontraction pushes the tricuspid valveinto the atrium and increases atrialpressure, creating a small wave into thejugular vein. It is normally simultaneouswith the carotid pulse.

RAPID EJECTION


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RAPID EJECTIONECG

No Deflections

RAPID EJECTION


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RAPID EJECTIONHeart Sounds

None


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REDUCED EJECTION

The end ofsystole

REDUCED EJECTION


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REDUCED EJECTIONHeart

At the end of this phase the

semilunar (aortic and pulmonary)

valves close.

REDUCED EJECTION


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REDUCED EJECTIONPressures & Volumes

After the peak in ventricular and

arterial pressures (red and

green), blood flow out of the

ventricles decreases and

ventricular volume decreasesmore slowly (white).

When the pressure in the

ventricles falls below the

pressure in the arteries, blood in

the arteries begins to flow backtoward the ventricles and causes

the semilunar valves to close.

This marks the end of ventricular

systole mechanically.

REDUCED EJECTION


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REDUCED EJECTIONECG

The T wave is due to ventricular repolarization. The end of the T

wave marks the end of ventricular systole electrically.

REDUCED EJECTION


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REDUCED EJECTIONHeart Sounds

None


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ISOVOLUMETRIC

RELAXATION

The

beginning of Diastole

ISOVOLUMETRIC RELAXATION


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ISOVOLUMETRIC RELAXATIONHeart

At the beginning of this phase the

AV valves are closed.



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ISOVOLUMETRIC RELAXATIONPressures & Volumes

Throughout this and the previoustwo phases, the atrium in diastolehas been filling with blood on topof the closed AV valve, causingatrial pressure to rise gradually

(yellow). The "v" wave is due to the back

flow of blood after it hits theclosed AV valve. It is the seconddiscernible wave of the jugularvenous pulse.

The pressure in the ventricles(red) continues to drop.

Ventricular volume (white) is at aminimum and is ready to be filledagain with blood.



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ISOVOLUMETRIC RELAXATIONECG

No Deflections



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ISOVOLUMETRIC RELAXATIONHeart Sounds

The second heart sound (S2, "dup") occurs when the semilunar

(aortic and pulmonary) valves close. S2 is normally split because

the aortic valve closes slightly earlier than the pulmonary valve.


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RAPID VENTRICULAR

FILLING

RAPID VENTRICULAR FILLING


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Heart

Once the AV valves open, blood

that has accumulated in the atria

flows rapidly into the ventricles.



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Pressures & Volumes

Ventricular volume (white)

increases rapidly as blood flows

from the atria into the ventricles.



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ECG

No Deflections



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Heart Sounds

A third heart sound (S3) is usually abnormal and is due to rapid

passive ventricular filling. It occurs in dilated congestive heart

failure, severe hypertension, myocardial infarction, or mitral

incompetence.


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REDUCED VENTRICULAR

FILLING

(Diastasis)

REDUCED VENTRICULAR FILLING


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Heart

Rest of blood that has

accumulated in the atria flows

slowly into the ventricles.



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Pressures & Volumes

Ventricular volume (white)

increases more slowly now. The

ventricles continue to fill with

blood until they are nearly full.



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ECG

No Deflections



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Heart Sounds

None

Hypertension


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Hypertension

Arterial pressure is too high Sometimes cause is unknown, or is secondary to disease Variety of causes/ risk factors are sedentary lifestyle smoking obesity diet (excess sodium; cholesterol; calories in general) stress arteriosclerosis

genetic factors

Consequences


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Consequences

heart has to work harder; left ventricle enlarges

atherosclerosis may affect coronary arteries

as well (which have to work harder anyway) deficient blood supply to other parts of body

damage to blood vessels

heart failure

Treatment


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ea e

Quit smoking; adjust diet; exercise

Drug therapies- strategies differ

Reduce heart rate calcium channel blockers

reduce calcium flow into heart muscle and thereforeheart rate, relax smooth muscle lining coronaryarteries

beta blockers (reduce stimulation bysympathetic nervous system)


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Vasodilators (such as nitroglycerin) open up

blood vessels (reduce resistance)

If heart is actually failing, digitalis increases

efficiency of heart muscle

Anti-hypertensive drugs may be taken incombination

Age related changes


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g g

cholesterol deposition in blood vessels

heart enlargement

death of cardiac muscle cells

increase in fibrous connective tissue of the heart

increase in adipose tissue of the heart

increase in blood pressure

decrease in resting heart rate


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Coronary artery disease results when coronaryarteries cannot deliver blood adequately

Usual cause: plaques in arterial walls

Angina pectoris (pain) results when body is notreceiving adequate oxygen

Myocardial infarction (heart attack) results whenblood supply to heart is completely blocked; muscledies

Conclusion


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To clinicians heart sounds provide importantinformation about the normal function of theheart and assist in diagnosing cardiacabnormalities. Any abnormal heart sounds

and certain murmurs are important indicatorsof specific cardiac abnormalities.

Hence, the integrated function of heart and

blood vessel constitute an important , basicpart of routine clinical examination andpractice.

References


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Understanding Human anatomy & Physiology : Sylvia Maden 2nd

Edition

Textbook of Medical Physiology : Guyton & Hall 9 th Edition Anatomy & Physiology : Seeley, Stephens, Tate 2nd Edition Essentials of Medical Physiology : K Sembulingam

Physiology : Berne, Levy 3rd edition Stanley Salmons. Text book of Grays Anatomy [P.L Williams] 38 th

edition Cunninghams manual of practical anatomy (vol. 2 Abdomen &

Thorax)

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