Cardio Vascular System Circulation ECG Heart Block Youtube Lecture Handouts

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Image of Cardio Vascular System

Image of Cardio Vascular System

Image of Cardio Vascular System

Image of Types of Distensible Vessels

Image of Types of Distensible Vessels

Image of Types of Distensible Vessels

Types of Vessels

  • Windkessel (distensible vessels)

  • Distributing vessels (arteries)

  • Resistance vessels (arterioles)

  • Exchange vessels (capillaries)

  • Venules & Veins

    Image of Details of The Capillary Network

    Image of Details of the Capillary Network

    Image of Details of The Capillary Network

    Table of Type of Vessel
    Table of Type of Vessel

    Type of vessel

    Diameter

    Functions

    Elastic art. (Large art.)

    Greater than 1 cm.

    Conduction of blood

    Muscular art. (Medium art.)

    0.1 to 10 mm.

    Distribute blood to arterioles

    Arteriole

    10 to 100 µm.

    Main site of peripheral resistance

    Capillary

    4 to 10 µm.

    Exchange of material at tissue level

    Venules

    10 to 100 µm.

    Collect blood

    Veins

    0.1 mm or greater

    Return blood to heart

Windkessel Vessels

  • Rich in elastic tissue show elastic recoil

  • Resists too much in BP during systole & too much ↓ in BP during diastole

  • Aging causes loss of elasticity & there is

    • ↑ in systolic BP

    • ↓ in diastolic BP

    • ↑ pulse Pressure

  • Example, aorta, pulmonary artery & their large branches

Resistance Vessels

Image of Resistance Vessels

Image of Resistance Vessels

Image of Resistance Vessels

  • Rich sym. Inner. Nerves normally discharge @ 1 impulse/sec. which can Increase upto 10 to 16 impulses/sec. Maximum vasoconstriction

  • It can decrease to 0.0 impulses/sec. Max. Vasodilatation

  • Example, Arterioles

Metarterioles & Pre-Capillary Sphincters

  • They control size of capillary bed

  • Their radius is controlled by

    1. Neurogenic factor ie. Symp. Fib.

    2. Local metabolites

  • Local dila. as ↑ CO2, ↑in pH.,↓ O2, K+ , ↑ temp,↑ lactic acid concern & adenosine

  • Local cons. as serotonin, ↓in temp.

Exchange Vessels

  • Are capillaries

Only 25% are open at rest

  • Dia. controlled by precapillary sph.

Types of Capillaries

1. Non-fenestrated or continuous present in most tissues, have 4 nm wide intercellular cleft. Glucose can pass but plasma proteins cannot. Example muscles, skin, connective tissues.

2. Fenestrated (pores of 20 to 100nm dia.) eg. Present in kidney, exo. & endocrinal glands, intestinal villi, choroid plexuses of brain

3. Discontinuous or sinusoidal they have large spaces between two cells, are present in bone marrow, liver & spleen

Non Fenestrated / Continuous

Image of Non Fenestrated For Capillaries

Image of Non Fenestrated for Capillaries

Image of Non Fenestrated For Capillaries

Fenestrated Capillaries

Image of Fenestrated For Capillaries

Image of Fenestrated for Capillaries

Image of Fenestrated For Capillaries

Discontinuous / Sinusoids

Image of Basement Membrane For Sinusoids

Image of Basement Membrane for Sinusoids

Image of Basement Membrane For Sinusoids

Sinusoids Image-2

Sinusoids Image-2

Sinusoids Image-2

Capacitance Vessels

  • About 60% of blood is present in veins

  • Veins can store large amount of blood by enlarging themselves

    Blood Reservoirs

  • Liver

  • Spleen

  • Skin

Image of Capacitance Vessels

Image of Capacitance Vessels

Image of Capacitance Vessels

Injury to Juglar Vein

Is life threatening because it can cause air embolism

Shunt Vessels

  • Also called preferential channels or thoroughfare channels

  • Provide direct connection between metarterioles and Venules

    Image of Shunt Vessels

    Image of Shunt Vessels

    Image of Shunt Vessels

Haemodynamics

  • Blood flow depends on pressure and resistance

  • Hagen-Poiseuille’s Law:

Types of Blood Flow

  • Normally Laminar or Streamlined velocity is greatest in the centre

  • Sometimes turbulent above critical level flow becomes turbulent

  • Turbulence depends on

  • Diameter of vessel &

  • Viscosity of blood

Streamline & Turbulent Flow

Image of Streamline and Turbulent flow

Image of Streamline and Turbulent Flow

Image of Streamline and Turbulent flow

Reynolds Number

  • Turbulence increases with the increase in Reynolds no.

  • It starts appearing at Re. no. 2000

  • Above Re. 3000 always present

    Image of Reynolds Number

    Image of Reynolds Number

    Image of Reynolds Number

Electrocardiogram

  • It is surface recording of electrical changes taking place in heart from beat to beat

  • Electrocardiograph is instrument used

  • Electrocardiography is branch of physiology related to recording and analysis of electrical activity of heart

  • Electrogram is the record

ECG

  • Recording Ecg

  • Record is taken on Ecg paper with the help of Ecg machine

    Image of Electrocardiogram

    Image of Electrocardiogram

    Image of Electrocardiogram

Body is a Volume Conductor

  • Heart is suspended in a conductive media

  • Body fluids surrounding the heart conduct the electricity very easily &

  • Potentials can be picked easily with electrodes

    Image of Body Is A Volume Conductor

    Image of Body is a Volume Conductor

    Image of Body Is A Volume Conductor

    Image of Right arm aVR+ And Left Arm aVL And Normal Electrical Axis

    Right Arm aVR+ and Left Arm aVL and Normal Electrical Axis

    Image of Right arm aVR+ And Left Arm aVL And Normal Electrical Axis

ECG: Leads

Recording is by Leads

Lead is a pair of electrodes

Leads are of two types

  • Bipolar &

  • Unipolar

Image of Recording Device

Image of Recording Device

Image of Recording Device

Image of Bipolar Lead and Unipolar Lead

Image of Bipolar Lead and Unipolar Lead

Image of Bipolar Lead and Unipolar Lead

Limb & Chest Leads

Bipolar

  • Limb leads- are used

  • Chest leads- not in use --- X

Unipolar

  • Limb leads replaced by Augmented limb leads

  • Chest leads- are in use

Bipolar leads

Both electrodes are recording electrodes & the recorded potential is

Difference of Potential between Two Points

Unipolar Leads

  • Unipolar leads-one electrode is called exploring / recording electrode

  • Another is indifferent electrode & is prepared by connecting three limb leads to a common terminal through electrical resistance. It records zero potential

  • Exploring electrode records absolute voltage

Routine 12 Lead ECG

A routine ECG has

  • Standard bipolar leads----- 3

  • Augmented limb leads------3

  • Unipolar chest leads---------6

Total 12 Leads

Other leads– Oesophageal leads, intracardiac leads & Rt. sided chest leads & posterior leads

Standard Leads

Bipolar leads (standard leads) – both electrodes are active

  • Lead I ----Rt. Arm –ve

    Lt. Arm +ve

  • Lead II----Rt. Arm -ve

    Lt. Leg +ve

  • Lead III---Lt. Arm -ve

    Lt. Leg +ve

Image of Standard Leads

Image of Standard Leads

Image of Standard Leads

Einthoven’S Triangle

  • It is the equilateral triangle with the Rt. & Lt. shoulders & Lt. leg as the three apices. The Rt. leg serves as a ground conductor.

  • If an arm is amputed, the electrode can be placed on the stump that is left

Einthoven’S Law

  • It states that if electric potentials of any two of the bipolar leads are known the potential of third one can be determined mathematically

  • According to it voltage in

    • I+III=II

    • I+ (-II) +III=0

Unipolar Leads

They are of two types

  • Unipolar Limb Leads are replaced by Augmented limb leads

  • Unipolar Chest Leads are in use

Augmented Limb Leads

Unipolar limb leads are replaced by augmented limb leads. Potential in augmented lead is 50% more than that of limb lead.

Three augmented limb leads are

  • aVR

  • aVL

  • aVF

Image of Connected Augmented Limb Leads

Image of Connected Augmented Limb Leads

Image of Connected Augmented Limb Leads

Image of Non-Connected Augmented Limb Leads

Image of Non-Connected Augmented Limb Leads

Image of Non-Connected Augmented Limb Leads

Image of Unipolar Chest Leads

Image of Unipolar Chest Leads

Image of Unipolar Chest Leads

Unipolar Chest Leads

Unipolar chest leads: total six in no.

  • V1—IV ICS. just to the Rt. of sternum

  • V2—IV ICS. just to the Lt. of sternum

  • V3—halfway between V2 & V4

  • V4—V ICS. midclavicular line

  • V5—same level as V4in ant. axillary line

  • V6—same level as V4,midaxillary line

    Image of Clavicula, Mid Clavicular Line And Mid Axillary Line

    Clavicula, Mid Clavicular Line and Mid Axillary Line

    Image of Clavicula, Mid Clavicular Line And Mid Axillary Line

    Image of Scapula For Chest Leads

    Image of Scapula for Chest Leads

    Image of Scapula For Chest Leads

    Image of Heart Orientation In Chest

    Image of Heart Orientation in Chest

    Image of Heart Orientation In Chest

    Image of The Cardiac Position and Axis Orientation of Chest

    Image of the Cardiac Position and Axis Orientation of Chest

    Image of The Cardiac Position and Axis Orientation of Chest

    Image of Electrocardiography

    Image of Electrocardiography

    Image of Electrocardiography

    Image of Big Square and Small Square

    Image of Big Square and Small Square

    Image of Big Square and Small Square

ECG: Reading

Basic Rules:

  • During most of depolarization base is –ve & apex +ve only during last part of depolarization it reverses it’s very brief period. Average current flow is from base to apex.

  • It is also mean electrical axis of heart.

  • During repolarization also current flow is from base to apex

    Image of ECG Paper

    Image of ECG Paper

    Image of ECG Paper

    Image of Mean Electrical Axis

    Image of Mean Electrical Axis

    Image of Mean Electrical Axis

Basic Rule

  • Flow of current towards recording electrode gives +ve deflection

  • Flow away gives –ve deflection

  • Magnitute of voltage depends on muscle mass

Image of Positive And Negative Deflection

Image of Positive and Negative Deflection

Image of Positive And Negative Deflection

Image of Positive and Negative deflection Circle

Image of Positive and Negative Deflection Circle

Image of Positive and Negative deflection Circle

ECG–Waves, Intervals & Segments

Normal ECG has

Waves

  • P

  • QRS

  • T

Intervals

  • PR

  • QT

Seg

  • Segments

  • PR &

  • QT

ECG–Waves, Intervals and Segments Image

ECG–Waves, Intervals and Segments Image

ECG–Waves, Intervals and Segments Image

P Wave

Wave of Atrial Depolarization +ve in Standard limb leads & - ve in a VR

  • Duration-----0.1 sec.

  • Voltage------0.25 mv or Amplitude

Abnormalities P Wave

  • Absent or replaced by very high speed fibrillatory waves – in Atrial fibrillation

  • P pulmonale - Large high voltage , in Rt Atrial hypertrophy

  • P mitrale –Broad & notched in Lt. Atrial hypertrophy

  • Inverted in nodal rhythm

QRS Complex

Is caused by ventricular depolarization it measures intraventricular conduction time

  • Duration---0.08- 0.12 sec.

  • Voltage 0.5 – 1.5 mv

Prominent Q wave indicates old infarction

Abnormalities of QRS Complex

Prolonged QRS complex seen in

  • Bundle branch block

  • Hypertrophy of ventricles

Prolonged & bizarre QRS

  • Cardiac muscle destroyed in various areas & replaced by fibrous tissue

  • Block in conduction of impulses by Purkinje system

T Wave

  • Produced by ventricular depolarization.

  • It is normally positive because apex of heart repolarizes earlier than the base

  • Duration--- 0.27 sec

  • Voltage ---- 0.5mv

Abnormalities of T Wave

  • Flattened in old age

  • High amplitude in exercise

  • Inverted in ischemia of heart

  • Abn. of T wave in lead I & II are of diagnostic importance in myocardial damage

Atrial Repolarization

  • Atrial repolarization wave not visible, merged with QRS complex, Sometimes U wave may be present. Caused by slow repolarization of papillary muscles

  • PR Interval — from beginning of P wave to beginning of Q/R wave. Time from atrial activation to the beginning of ven. depol.

Normal------ 0.12 to 0.2 Sec

>0.2 sec-----

I degree heart block

<0.12 sec----

  • Nodal rhythm

  • WPW syndrome

Intervals

QT interval---from the beginning of Q wave to the end of T wave. It represents ventricular depolarization & repolarization time

  • Duration—0.40 to .43 sec

  • Prolonged in ventricular conduction defects

P-P interval--- interval between two successive beats, normally equal

Segments

  • PR segment is Isoelectric period from the end of P wave to the beginning of Q wave

    Duration—0.04 sec

  • ST segment is isoelectric period from the end of S wave to the beginning of T wave

    Duration—0.04 to 0.08 sec

ECG—ST Seg. Shift

  • Whenever current of injury is present ST Seg. & TP seg. are not at same level

  • Actually TP seg. Shifts but

  • We record it as shift of ST Seg.

  • It records presence of current of injury

J Point

  • Point of no electrical activity potential is zero

  • Point between S wave & beginning of ST Seg.

Calculating HEART RATE from ECG

Important points

  • ECG paper moves at a speed of 25 mm/sec

  • So in 1 minute paper will move 25 X 60 =1500 mm (1500 small squares or 300 big squares)

  • Count no. of small squares between two R, R waves say it is n

  • Heart rate is = 1500 / n or

  • Count no. of big squares, say N

Now heart rate is = 300 / N

Cardiac Vector

Vector is an arrow, depicting two things

  • Direction of current flow, arrow points always towards positive side

    ve +ve

  • Length of arrow is proportionate to magnitude of voltage

Image of Cardiac Vector

Image of Cardiac Vector

Image of Cardiac Vector

Calculation of the Mean Electrical Axis

Calculation of the Mean Electrical Axis Image

Calculation of the Mean Electrical Axis Image

Calculation of the Mean Electrical Axis Image

Mean Electrical Axis of Heart

During most of the ventricular depolarization vector is from base to apex. This is called Mean Electrical Axis of heart

Normally it is

Range is Lt.

Image of Mean Electrical Axis of heart

Image of Mean Electrical Axis of Heart

Image of Mean Electrical Axis of heart

Image of ECG Hexaxial System

Image of ECG Hexaxial System

Image of ECG Hexaxial System

Normal Axis Deviations

  • Normal Lt. Axis deviation-horizontal position of heart:

  • Normal Rt. Axis deviation-Vertical position of heart:

  • Oblique position of heart:

    Image of Normal Axis deviations

    Image of Normal Axis Deviations

    Image of Normal Axis deviations

    Image of Vertricular Hypertrophy

    Image of Vertricular Hypertrophy

    Image of Vertricular Hypertrophy

Abnormal Axis Deviations

  • Lt. Axis deviation

  • Lt Ven. Hypertrophy

  • Lt. Bundle branch block

ECG Findings:

  • Lead I--- prominent R wave

  • Lead III- prominent S wave

  • (R1 S3 pattern)

  • Rt. Axis deviation -Axis Rt. To

  • Rt. Ven. Hypertrophy.

  • Rt. Bundle branch block

ECG Findings

  • Lead I---- prominent S wave

  • Lead III– prominent R wave

  • (S1 R3 pattern)

Abnormal ECG

ECG in

  • Heart Block

  • Ectopic cardiac rhythm

  • Myocardial Infarction

  • Change in ionic composition

Heart Block

Conduction of impulse from Pace maker is interrupted Can be

  • SA (Sino atrial) block

  • AV (Atrio ventricular) block

  • Bundle Branch Block

Image of Heart Block

Image of Heart Block

Image of Heart Block

SA Block / Arrest

  • Initially heart stops beating

  • After some time a new Pacemaker starts functioning.

  • Heart resumes its function

  • It starts beating at a new rhythm

SICK SINUS SYNDROME

Sick Sinus Syndrome -Diseases affecting sinus node lead to marked bradycardia associated with dizziness & syncope

Image of Cross-Section of The Chest With a Pacemaker

Image of Cross-Section of the Chest with a Pacemaker

Image of Cross-Section of The Chest With a Pacemaker

Image of Sick Sinus Syndrome

Image of Sick Sinus Syndrome

Image of Sick Sinus Syndrome

Image of Sinus Pause

Image of Sinus Pause

Image of Sinus Pause

S-A Block with A-V Nodal Rhythm

Image of S-A Block With A-V Nodal Rhythm

Image of S-A Block with A-V Nodal Rhythm

Image of S-A Block With A-V Nodal Rhythm

First Degree Heart Block

  • All impulses reach to the ventricles

  • Prolonged P-R interval > 0.2 sec.

  • Rate of atrial & ventricular contractions are same

ECG

Image of First Degree Heart Block

Image of First Degree Heart Block

Image of First Degree Heart Block

Second Degree Heart Block

Mobitz type I Wenckebach phenomenon Gradual increase in PR interval, till one beat drops

Image of Second Degree Heart Block Type-I

Image of Second Degree Heart Block Type-I

Image of Second Degree Heart Block Type-I

Mobitz Type II - all impulses are not conducted

  • 2: 1 Block alternate impulses conducted

  • Atrial : ventricles rate --- 2:1

  • 3:1 Block ratio is --------- 3:1

    Image of Second Degree Heart Block Type - II

    Image of Second Degree Heart Block Type - II

    Image of Second Degree Heart Block Type - II

III Degree Heart Block

Impulses not conducted from Atria to Ventricles

  • Caused by organic diseases of heart

  • Atrioventricular dissociation

  • Remaining nodal tissue becomes pacemaker. The rhythm generated is Idioventricular Rhythm

  • Rate of Idioven. Rhy. is about 45 beats

Strokes-Adams Syndrome

  • If ventricular pacemaker is located more peripherally in the conducting system ventricular rate is lower

  • Rate can be as low as 15 beats/min.

  • Delayed pickup of heart is there, delay can be of 5 to 30 seconds

  • Delay caused by overdrive supression

Resultant Cerebral Ischemia Causes Dizziness & Fainting

Image of Resultant Cerebral Ischemia Causes Dizziness And Fainting

Cerebral Ischemia Causes Dizziness and Fainting

Image of Resultant Cerebral Ischemia Causes Dizziness And Fainting

Image of Complete AV Block Hrart Block

Image of Complete AV Block Hrart Block

Image of Complete AV Block Hrart Block

Atrio-Ventricular Dissociation

Image of Atrio-Ventricular Dissociation

Image of Atrio-Ventricular Dissociation

Image of Atrio-Ventricular Dissociation

Bundle Branch Block

  • Block in one or more branches of bundle of His

  • QRS complexes prolonged & deformed

  • Axis deviation present

His Bundle Electrogram

Image of His Bundle Electrogram

Image of His Bundle Electrogram

Image of His Bundle Electrogram

Arrhythmias

Two types:

  • Physiological

  • pathological

Physiological Arrhy.

Rhythm is generated at SA node

Normocardia normal resting heart rate of 60 to 100 beats/min.

Sinus Bradycardia

Image of Sinus Bradycardia

Image of Sinus Bradycardia

Image of Sinus Bradycardia

Sinus Tachycardia

Image of Sinus Tachycardia

Image of Sinus Tachycardia

Image of Sinus Tachycardia

Sinus Arrhythmia

Image of Sinus Arrhythmia

Image of Sinus Arrhythmia

Image of Sinus Arrhythmia