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The Cardiovascular System:The Heart

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Embryology of the Heart

• Derived from mesoderm, begins development at 3rd week of gestation

• Contraction of the heart begins by day 22

• A pair of tubes develop (endothelial tubes),

• These fuse into the primitive heart atria and ventricles form

• These then assume a “U” shape then an “S” shape– Making “US”

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The Heart

• Cardiovascular system – heart, arteries, veins and capillaries

• 2 major divisions:

• 1. Pulmonary circuit - right side of heart– carries deoxygenated blood to lungs

• 2. Systemic circuit - left side of heart– supplies oxygenated blood to the body

• Cardiology- study of the heart

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Cardiovascular System Circuit

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Size, Shape and Position• Big a closed fist, males

have bigger anatomical hearts

• Located in the mediastinum, like a cone on its side between the lungs

• Base - broad superior portion of heart

• Apex - inferior end, tilts to the left, tapers to point

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Pericardium• Pericardium- surrounds heart, keeps your heart in

it’s place (like a father-in-law with the gun collection)

• Allows heart to beat without friction, room to expand and resists excessive expansion

• Pericarditis= inflammation of pericardium, can result in:

• Cardiac Tamponade= fluid in the pericardial cavity compressing the heart, can stop the heart beat

Pericardium

• Pericardium- Two parts:

• 1.) Parietal Pericardium – Two layers:– Fibrous layer- superficial

• protects, prevents overstretching, anchors heart

– Serous layer- deep

• 2.) Visceral Pericardium– Also called the

epicardium 7

Heart Wall• 3 layers of the Heart

wall– 1.) Epicardium- outside

slippery layer• Also called the visceral

pericardium (just to be confusing)

– 2.) Myocardium- muscle of heart

– 3.) Endocardium- inside the heart, covers chambers, heart valves

• The heart can’t get oxygen from the inside. Why? 8

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Heart Chambers• 4 chambers• Right and left atria (= entry halls)

– 2 superior, posterior chambers– receive blood returning to heart

• Right and left ventricles (= little bellies) – 2 inferior chambers– pump blood into arteries– Left ventricle is thicker, why?

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Anterior Anatomy – Atrioventricular sulcus - separates atria, ventriclesAnterior and posterior interventicular sulci - grooves separate ventricles

Atrioventricular sulcus

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Posterior Heart Anatomy

Posterior Interventricular Sulcus- groove separating ventricles

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Heart Chambers - Internal

• Interatrial septum– wall that separates atria

• Pectinate muscles– internal ridges of myocardium in right atrium and both

auricles

• Interventricular septum– wall that separates ventricles

• Trabeculae carneae– internal ridges in both ventricles walls

• Chordae tendineae- cords connecting to the tricuspid and mitral valves

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Internal Anatomy Anterior Aspect

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Heart Valves

• Ensure one-way blood flow

• Semilunar valves - control flow into great arteries– pulmonary: from right ventricle into pulmonary trunk– aortic: from left ventricle into aorta

• Atrioventricular (AV) valves– right AV valve has 3 cusps (tricuspid valve)– left AV valve has 2 cusps (mitral, bicuspid valve)

• rat lamb

– chordae tendineae - cords connect AV valves to papillary muscles (on floor of ventricles)

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The Mitral Valve

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Heart Valves

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Valve Anatomy

• The AV valves, the tricuspid and bicuspid (mitral) valves

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AV Valve Mechanics

• Ventricles relax, pressure drops, semilunar valves close, AV valves open, blood flows from atria to ventricles

• Ventricles contract, AV valves close (papillary m. contract and pull on chordae tendineae to prevent prolapse), pressure rises, semilunar valves open, blood flows into great vessels

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Operation of Atrioventricular Valves

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Operation of Semilunar Valves

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Be the Blood- Drawing

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Be the Blood - Discretion I• You (blood) flow into heart in the Superior (S)

vena cava and inferior (I) vena cava and then into the right atrium (1)

• You pass through the tricuspid (= three points) valves (2) into the right ventricle (3)

• You go through the pulmonary semilunar (4) valves into the pulmonary trunk (5)

• The pulmonary trunk divides into right and left pulmonary arteries (6) which go to the lungs so that you can be oxygenated

Be the Blood II

• You (be the blood!) then flow from the lungs through the pulmonary veins (7) into the left atrium (8)

• Through the bicuspid valve (9) to the left ventricle (10)

• The left ventricle pumps blood (you) through the aortic semilunar valve (11) into the ascending aorta (12) then to the aortic arch and on to the descending aorta

• http://www.youtube.com/watch?v=upctPUa6RhA

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Circulation to the Heart

• The heart can not get nutrients from inside

• Blood vessels must supply the heart muscle this is called the coronary circulation

• The arteries of the heart encircle it like a crown

• While contacted no blood flows to the heart

• When the heart relaxes the blood flows to it

• FLOW- Aorta to coronary arteries to coronary veins

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Heart Valves

2 ?1?

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Coronary Circulation• Left coronary artery

– 1. anterior interventricular artery• supplies interventricular septum + anterior walls of ventricles

– 2. circumflex artery• passes around left side of heart in coronary sulcus, supplies left atrium

and posterior wall of left ventricle

• Right coronary artery– 1. posterior interventricular artery

• supplies posterior walls of ventricles

– 2. marginal artery• supplies lateral R atrium + ventricle

Coronary Circulation memory aid

• Remember: a heart that doesn’t work well will often- LAC RPM – Right Coronary artery gives off the- – Right Posterior Interventricular artery and Marginal

artery (RPM)– Left Coronary artery gives off the-– Left Anterior Interventricular artery and the Circumflex

artery (LAC)

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Coronary Vessels – Anterior---LAC RPM---

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Coronary Vessels – Posterior---LAC RPM---

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Structure of Cardiac Muscle

• Compared to skeletal muscle cardiac muscle is:

• Short in length

• Branched

• One to two nuclei

• Has intercalated discs, these contain gap junctions that assist in electrical conduction

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Structure of Cardiac Muscle Cell

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Metabolism of Cardiac Muscle

• Aerobic respiration

• Rich in myoglobin and glycogen

• Large mitochondria

• Organic fuels: fatty acids, glucose, ketones– What should our diets be?

• Fatigue resistant

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Heart Electrical Conduction

• Myogenic - heartbeat originates within the heart

• The fundamental rhythm of the heart is automatic and not dependent on the nervous system or endocrine system

• This rhythm is due to autorhythmic cells, specialized cardiac muscle fibers that are self-exciting

• These cells act as: a Pacemaker…– Setting the rhythm of the entire heart

• …and Conduction system– A route for conducting electrical energy throughout the heart

muscle

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It’s All In The Timing• The chambers of the heart have to be coordinated or the

heart will not work• The SA node (sinoatrial node) stimulated first, as the

name implies this node causes atria contraction• Next the AV node (atrioventricular node) is stimulated• The impulse then goes to the Bundle of His

(Atrioventricular bundle)• The right and left bundle branches goes to the apex of

the heart• Finally, conduction myofibers termination is called

Purkinje fibers that conduct impulses to the rest of the heart

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Cardiac Conduction System

Bundle of His

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Heart Conduction: Memory Aid

• Remember: SAVe HIS Right and Left BUN from PURKing

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Cardiac Rhythm

• Systole = contraction; diastole = relaxation

• Sinus rhythm– set by SA node, adult at rest is 70 to 80 bpm

• Ectopic foci - region of spontaneous firing (not SA)– nodal rhythm - set by AV node, 40 to 50 bpm – intrinsic ventricular rhythm - 20 to 40 bpm

• Arrhythmia - abnormal cardiac rhythm– heart block: failure of conduction system

• bundle branch block

• total heart block (damage to AV node)

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Electrocardiogram (ECG)• Composite of all action potentials of nodal and

myocardial cells detected, amplified and recorded by electrodes on arms, legs and chest

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ECG Alphabet

• The ECG alphabet goes PQRST

• P wave- the first wave shown

• QRS complex- the middle quibble

• T wave- the last wave

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Pacemakers

• The SA node is the pacemaker of the heart

• If the SA node becomes diseased, and heart rate gets too low (<40 BPM) an Artificial Pacemaker can be surgically implanted

• Other sites besides the SA node can stimulate the heart, this is called: an Ectopic pacemaker– Triggers of this activity are caffeine, nicotine, that

special someone

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EKG/ ECG

• Cardiac muscle contraction is electrical, the physiology is similar to skeletal muscle (see A&PI) these electrical impulses can be detected on the skin of the chest

• Our friend the Aardvark!• This recording is called is called an

Electrocardiogram and the machine is called an Electrocardiograph

• The ECG tells three things: E- electrical conduction problems in the heart, C- cardiac enlargement, G- Cardiac Damage

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Waves of Meaning I

• First wave= P wave- atrial Depolarization

• Second wave= QRS- ventricular depolarization as the electrical excitement spreads through the ventricles– Repolarization of the atria occurs here but is not seen

due to the QRS length

• Third wave= T wave- ventricular REploarization

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• ECG/EKG• Abnormal Waves• Larger P= enlarged

atrium• Enlarged R= enlarged

ventricles

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• EKG (ECG)• Time span between waves is

called intervals or segments

• P-Q interval lengthened- coronary artery disease, rheumatic fever

• Q-T interval lengthened- myocardial damage, HEART ATTACK, coronary ischemia or conduction anomalies

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ECGs, Normal & Abnormal

No P waves

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ECGs, Abnormal

Extra systole: note the inverted QRS complex, misshapen QRS and T and absence of a P wave preceding this contraction.

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ECGs, Abnormal

Arrhythmia: conduction failure at AV node

No pumping action occurs

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Cardiac Cycle

• Events in one heartbeat

• Systole is contraction, Diastole is relaxation (“Relax? Relax? When I die, then I’ll relax.”)

• The cycle consists of systole and diastole of both atria plus systole and diastole of both ventricles

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Heart Sounds

• Listening to the sounds of the body is called auscultation (= listening), you can hear bowel sounds, breathing, and heart beats with your ear to the patient (old method) or with a stethoscope (modern method)

• 4 heart sounds, 2 clinically important (because a stethoscope can hear them):

• The first sound is lubb,– First heart sound (S1), louder and longer “lubb”, occurs with

closure of AV valves

• The second sound is dub – Second heart sound (S2), softer and sharper “dub” occurs with

closure of semilunar valves

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Lubb- Dub

• Lubb- closure of AV valves:– Tricuspid valve

– Mitral valve

• Dub- closure of the semilunar valves:– Aortic

– Pulmonary

Lubb

LubbDub

Dub

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Auscultation of the Ticker• Provided your patient does not have situs inversius listen

to the heart in the following manner:• 1.) Aortic valve is heard at the right 2nd and 3rd intercostals

space just lateral to the sternum • 2.) Pulmonary Valve is heard at the left 2nd / 3rd

intercostals space just lateral to the sternum • 3.) Tricuspid valve is heard at the 5th and 6th intercostals

space lateral to the zyphoid process• 4.) Bicuspid valve is heard at the 5th and 6th intercostals

space in the midclavicular line (in line with the left nipple)• (Anatomy & Physiology- aortic and pulmonary valves,

Try and Buy- tricuspid and bicuspid valves)

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Auscultation of the Ticker

A P

TM

----

----

----

--

Midclavicular line

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Abnormal Sounds

• We should hear only ____ ____ at each of the four heart auscultation areas if not:

• A heart murmur may be present- rushing, gurgling noise heard during or after normal heart sounds– Usually benign

• Murmurs: mitral stenosis is from scar tissue due to Rheumatic fever, mitral insufficiency from regurgitation of blood from the left ventricle into the left atrium, mitral valve prolapsed, aortic stenosis, aortic insufficiency causing backflow from the aorta into the left ventricle.

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3 Phases of the Cardiac Cycle

• Lasts <1 second and is centered in the ventricles:• 1.) Isovolumetric relaxation: ventricles relax (T wave)

– No ejection of blood yet (no change in volume)

• 2.) Ventricular Filling: blood flows into the ventricles, is called End Diastolic Volume (EDV)

• 3.) Ventricular Systole: contraction of the ventricles (QRS complex), includes isovolumetric contraction- when all four valves are closed (so the volume remains the same, and muscle fibers in isometric contraction. Ventricular ejection- the semilunar valves open

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Volumes and Volumes

• End-diastolic volume (EDV)- occurs in ventricular filling during the cardiac cycle, this is the volume left in the ventricles before they contract, about 130 mL

• End-stroke volume (ESV)- volume of blood left in a ventricle at the end of contraction, about 60 mL

• Stroke volume (SV)- the volume of blood ejected per beat, usually 2 oz or 70mL

• Stroke volume formula= ESV subtracted from EDV gives us SV (130-60=70)

• Weight of an elephant

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HEART DIS-EASE Congestive Heart Failure

• Congestive Heart Failure- heart contraction is faulty, muscle becomes stretched and weaker with increased volume– Peripheral edema (swollen feet and ankles) if right

ventricle fails• Remember that peRIpheral edema is from the RIght ventricle

– Pulmonary edema if left ventricle fails

• ABCDEs of CHF= Acidosis, Blue skin, Cold skin, Dilated heart, Edema

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Heart Rate

• Measured from pulses

• Average: 70-80

• Tachycardia: persistent, resting adult HR > 100– stress, anxiety, drugs, heart disease or fever

• Bradycardia: persistent, resting adult HR < 60– common in sleep and athletes

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Regulation of Heart Rate• Cardiovascular center- in the medulla oblongata regulates

heart rate– The limbic system can influence the medulla– Vagus nerve (X) decreases heart rate at SA,AV nodes– vagal tone: background firing rate holds HR to sinus rhythm of

70 to 80 bpm• severed vagus nerves - SA node fires at intrinsic rate-100bpm

• Proprioceptors in the muscles, tendons and joints send input to the medulla and this increases heart rate

• Chemoreceptors- monitor chemical changes in the blood• Baroreceptors- monitor blood pressure in major arteries

and veins– Found in the arch of the aorta and the carotid arteries (feel them,

but be sitting down!)

Baroreceptors

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HEART DIS-EASE I• Coronary Artery

Disease (CAD)- atherosclerotic plaques in coronary arteries– Risks- high blood

pressure, cholesterol, homeocystine, smoking, obesity, diabetes, Type “A” personality, SITentary

• Myocardial Ischemia- angina pectoris– Treatment:

nitroglycerine 60

HEART DIS-EASE II• Myocardial Infarction (MI)

– Sudden death of heart tissue caused by sudden interruption of blood flow (infarct) from vessel narrowing with occlusion

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Heart Risk factor- Earlobe Crease• The earlobe crease may be

related to atherosclerosis.• The presence of the crease

should not be taken a an infallible predictor of disease.

• The earlobe crease should only be included as a risk factor along with family history, smoking, etc.

• (This is not a risk factor in Asians or American Indians.)

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HEART DIS-EASE III

• Arrhythmias- general term for irregular heart beat, due to caffeine, nicotine, vitamin B deficiency, drugs, anxiety, decrease minerals like K+

• Heart Fibrillations- Two kinds:– Atrial fibrillation- asynchronise beating, LIVE– Ventricular fibrillation- asynchronise beating,

DEATH• Remember: (In A FIb- they tell A lie about dyeing, in V fib

they lie in a graVe)

Holes In The Heart– 1) Ventricular Septal

Defect• A hole between the

right and left ventricals

– 2) Atrial Septal Defect • A hole between the

right and left atrium• Normally, The

foramen ovale (open hole) becomes the fossa ovalis (closed hole) 64

Hole Outside the Heart• Patent Ductus

Arteriosus- Hole outside the heart (Patent = Open)– The ductus arteriosus

doesn’t close

• Ductus Arteriosus-– temporary fetal shun that

carries blood from the pulmonary trunk into the aorta , blood is diverted away from the lungs

– Usually, the Ductus Arteriosus closes and becomes the Ligamentum Arteriosum

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Terms of the Heart

• “I love you”

• Cardiac arrest- Heart stopping or in ventricular fibrillation, neither is good

• Cardiomegaly- Big heart

• Corpulmonale- Right ventricular hypertrophy from hypertension in the pulmonary circulation

• Palpitation- fluttering of the heart, leaving a friend

• Paroxysmal tachycardia- rapid heartbeat that starts and ends suddenly

• Sudden cardiac death- stopped circulation

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Heart Issues

• Risk for Heart Disease = Family history, smoker, over weight, no exercise, ear crease, ugly

• Cholesterol- Above 200– Subtraction- Cholesterol restricted diet has minimal effect– Addition- Add fiber (oatmeal), lecithin, niacin, red yeast

• Homocysteine– Vitamin B complex and folic acid

• C-Reactive Protein– Non-specific indicator of systemic inflammation that may

indicate the process of atherosclerosis.

C-Reactive Protein

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Exercise and the Heart• Aerobic- in the zone for twenty minutes 3-5 times per

week= heart health• Zone= 180 minus your age is low range and plus 10 is the

high range• Benefits:

– increased oxygen to tissues by increasing maximum cardiac output

– More capillaries- collateral circulation increases, can survive a heart attack

– Long heart beat around 60 BPM the heart can rest more– Normalize blood pressure– Reduce depression and anxiety, – Stroke prevention by dissolving blood clots– Can control weight

Alternative Medicine for Heart Dis-ease

• Chelation therapy –intravenous solution of vitamins and EDTA

• EDTA appeared to reduce: – Symptoms of angina

pectoris– Aberrant cholesterol

metabolism– Impotency– Symptoms of

atherosclerotic disease

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Treatment of Heart Disease• Traditional Heart Treatment

– Traditional Open heart surgery– Robotic surgery

• Balloon angioplasty, stints

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