1- pathophysiology of cardiovascular system

7/28/2019 1- Pathophysiology of Cardiovascular System

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Pathophysiology of

Cardiovascular system


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Heart -gross anatomy

Apex


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Heart -internal anatomy


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Normal Features

Heart bomb about 6000 L of blood /day Heart weight: 250-300 grams

40% of all deaths are due to heart problems

Wall thickness ~ pressure (i.e., a wall is only asthick as it has to be)

LV= 1.5 cm

RV= 0.5 cm

Atria = 0.2 cm

Systole/Diastole


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Cardiac output (C.O.P)

It is the measure of the efficiency of the heart.

Increased COP due to increased physical

activity: exercise

Decreased COP due to decreased physical

activity: rest; sleep.

Normal COP = 5L\m


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Cardiac cycle

It consists of period of

contraction (systole)

during which the bloodis ejected from the

heart; and period of

relaxation (diastole)

during which the heartfills with blood.

Stroke volume

It is the amount of the

blood that is ejected

from the heart with each

heart beat


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Cardiac output

4.9 L/min

70 bpm 70 mls


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Common symptoms of cardiac diseases

Dyspnea:

congestive right side heart failure

pulmonary (lung) congestion

Cough stained with blood:

mitral stenosis

pulmonary venous congestion


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Chest pain:

myocardial infarction

angina

Cyanosis:bluish discoloration of skin and

mucus membranes

congenital heart diseasesaortic stenosis


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Symptoms of systemic venous congestion

- Edema of the lower limp

- Ascities: effusion in the peritoneal cavity

- GIT problems: dyspepsia


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Heart Beat Anatomy

Sinus Node (SA Node)

Atrioventricular Node (AV Node)

Bundle of His


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Valves

AV:

Tricuspid

Mitral Semilunar:

Pulmonary

Aortic


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Cardiac Aging

Chambers

Sigmoid-shaped

ventricular septum

Decreased left

ventricular cavity size

Increased left atrial

cavity size

Valves

Fibrous thickening of

leaflets

Mitral valve annular

calcific deposits

Aortic valve calcific

deposits


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Cardiac Aging

Coronary arteries

Atherosclerotic plaque

Calcific deposits

Increased cross-

sectional luminal area

Tortuosity

Myocardium

Brown atrophy

Increased

subepicardial fat

Increased mass


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Brow atrophy (aging) of the

heart


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Reflex control of heart rate


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Arrhythmias


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Conductivity of the Heart

Sinus Node(SA Node)

Atrioventricular Node (AV Node)

of His BundleBranches Purkinje Fibers

Bundle Branches


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Impulse Formation In SA Node


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Atrial Depolarization


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Delay At AV Node


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Conduction Through Bundle Branches


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Conduction Through Purkinje Fibers


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Ventricular Depolarization


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Plateau Phase of Repolarization


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Final Rapid (Phase 3) Repolarization


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Normal ECG Activation


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Reading ECGs


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Abnormal Heart Rhythms

Abnormal heart rhythms (arrhythmias) are sequences of

heart beats that are irregular, too fast, too slow, or

conducted via an abnormal electrical pathway through

the heart.

Disorders of impulse formation and conduction result in

brady-arrhythmias and tachy-arrhythmias


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Slow arrhythmias (brady-arrhythmias) may be

caused by pain, hunger, fatigue, digestive

disorders (such as diarrhea and vomiting), or

swallowing, which can stimulate the vagus

nerve excessively.

(With enough stimulation, which is rare, the

vagus nerve can cause the heart to stop).


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Fast arrhythmias (tachy-arrhythmias) may be

caused by exercise, emotional stress, fever,

excessive alcohol consumption, smoking, or

use of some drugs.

In most of these circumstances, the

arrhythmia tends to resolve on its own.


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Brady/Tachy Syndrome


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Examples of

ECGs seen with

abnormal

heart rhythms


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Abnormal Heart Rhythms

Atrial Fibrillation

Atrial Premature Beats

Bundle Branch Block

Heart Block

Paroxysmal Supra-ventricular Tachycardia

Ventricular Fibrillation

Ventricular Premature Beats

Ventricular Tachycardia


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Vascular diseases


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Aneurysms

Aneurysms Are localized abnormal dilations in ablood vessel or the wall of the heart. They could

be true, false, or dessicting aneurisms.

True aneurysm (limited by arterial wallcomponents or attenuated myocardial wall):

mediated by

Atherosclerotic

Congenital aneurysm (small BV, cerebral vesseles)

Ventricular (post-infarction)


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Vascular aneurysms are due to:

- Atherosclerosis - Traumatic

- Cystic medial necrosis - Congenital

- Inflammation

According to the size and/or shape it can be:

- Saccular (small portion of vessel)

- Fusiform


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Shape Of Aneurysm May Give Clue As To

Etiology

Saccular Aneurysm

Ostium


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Fusiform aneurysm:

dilated full circumference of artery


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Atherosclerosis


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Normal muscular artery


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Chronic inflammatory disorder of intima of

large blood vessels characterised by formation

of fibro-fatty plaques called atheroma.

Hardening-------------sclerosis


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Definition Of Atherosclerosis

A disease of the arterial intima affecting elastic

(large) & medium sized arteries that is

characterized by intimal plaques (lipid core

covered by a fibrous cap) that obstructs the

lumen, weakens the wall and may lead to

athero-embolism.


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Atherosclerosis is acondition in which patchy

deposits of fatty material called atheromas or

atherosclerotic plaques (consists of focal intimal

accumulations of lipids, complex carbohydrates,

blood & blood products, fibrous tissue & calcium

deposits, associated with changes in the media)

develop in the walls of arteries, leading to reduced

or blocked blood flow.


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Atherosclerosis can affect the medium-sized and

large arteries of the brain, heart, kidneys, other

vital organs, and legs.


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Atheroma Aorta:


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Introduction:

Large elastic arteries Starts in Intima

Fat deposits, Hardening and destruction.

Major cause of IHD, MI & Stroke.

Better understanding & Change in life style.


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Risk Factors:

Non modifiable

Age middle to late.

Sex Males,

complications

Genetic -Hyperchol.

Family history.

Potentially Modifiable

Hyperlipidemia:

Hypertension.

Smoking.

Diabetes

Life style, diet, exercises


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Pathogenesis:

Unknown etiology : Hyper-lipidemia, life style,

hypertension, smoking, genetic etc.

Starts with Initial intimal injury, inflammation, necrosis,

Lipid accumulation, Fibrosis -Atheroma.

Leads to Obstruction or destruction of vessel

Organ damage due to ischemia. Complications: Thrombosis, embolism, aneurism,

dissection & rupture.


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Common Sites:

Aorta, Carotid & Iliac. (large vessels)

Coronary

Renal

Abdominal

Limbs


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Morphology:

Fatty Dots

Fatty Streaks

AtheromatousSoft Plaque

FibrofattyHard Plaque

ComplicationsUlceration, Rupture, Hemorrhage, Thrombosis

Athero-emboli or cholesterol emboli.


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Complications:

Heart attack

Myocardial infarction.

StrokeCerebral infarction

Gangrenetissue infarction.

Kidney failureKidney infarction.

Aneurysms

Rupture

Thrombo-embolism.


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Fatty Streaks

Same aortastained with fat

stain


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MILD ADVANCED


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Fatty streak

Progressing

fatty streak


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Atherosclerotic Plaque Types

Stable

Unstable

1- pathophysiology of cardiovascular system

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