What is coronavirus/ COVID-19 ? Symptoms & Complications

What is coronavirus ?


Coronavirus is a type of virus. it is a largest category for an RNA virus. there are many different kinds, and some cause disease. a coronavirus disease COVID-19 as an infection disease identified in December 2019, caused by SARS-CoV-2 virus, a pandemic of respiratory illness, called COVID-19.

SARS-CoV-2 stands for Severe Acute Respiratory Syndrome.
 

COVID-19 stands for :- 

'CO' stands for corona, 'VI' stands for virus 'D' stands for disease. This disease was referred to as '2019' novel 'coronavirus' or '2019-nCoV'. The coronavirus is a new virus linked to the same family of viruses as SARS and some types of common cold. 

Coronavirus / COVID-19



Where was COVID-19 first discovered ?


The first known infection from SARS-CoV-2 were discovered in Wuhan, China.



Who issued the official name of COVID-19 ?


The official names of COVID-19 and SARS-CoV-2 were issued by the WHO on 11 February 2020.




How does COVID-19 spread between people ?


We known that the disease is caused by the SARS-CoV-2 virus, which spreads between people by several different ways -

The virus can spread from an infected person's mouth or nose in small liquid particles when the cough, sneeze, speak, sing or breath. These particles range from larger respiratory droplets to smaller aerosols.  

Direct close contact :- one can get the infection by being close contact with COVID-19 patients with in 1 meter of the infected person especially if they do not cover their face when coughing or sneezing.   

Indirect contact :- the droplets survive on surfaces and cloths of many days. Therefore, touching any such infected surface or cloth and then touching one's mouth, nose eyes or shakes your hand can transmit the disease. 
Larger droplets may fall to the ground in a few seconds, but tiny particles can linger in the air and accumulate in indoor places, especially many people are gathered and their is poor ventilation. 

One recent small study say that the virus is also sometimes found in the faeces but rarely in blood.    


 What is the incubation period for COVID-19 ?


An incubation period is the time between when you contract a virus and when your symptoms start.

According to the CDC (Centers for disease control and prevention) in December 2020, the symptoms show up people within 2 to 14 days after exposure to the virus.

A person infected with the coronavirus is contagious to others for up to 2 days before symptoms appear, and they remain contagious to others for 10 to 20 days, depending upon their immune system and the severity of their illness. 

for many people, COVID-19 symptoms start as mild symptoms and gradually get worse over a few days.




What are symptoms of coronavirus ?


Most Common Symptoms :-

  • Fever
  • Cough 
  • Congestion or runny nose 
  • Nausea or Vomiting
  • Tiredness
  • Loss of taste or smell 

Less Common Symptoms :-

  • Headache
  • Sore Throat 
  • Muscle or body aches and pains 
  • Diarrhea 
  • Red or irritated eyes 
  • A rash on skin 
  • Discoloration of finger and toe  

Serious Symptoms :-

  • Breathing Difficulty 
  • Shortness of breath 
  • Chest Pain 
  • Loss of speech, mobility or confusion  

Some people infected with the coronavirus have mild COVID-19 illness, and others have no symptoms at all. 

In some cases, COVID-19 can lead to respiratory failure, lasting lung and heart muscle damage, nervous system problem, kidney failure or death

Seek immediate medical attention if you have serious symptoms. Call your doctor or a heath care provider explain your symptoms over the phone before visiting doctors office or a health care facility. 

People with mild symptoms who are otherwise healthy should manage their symptoms at home. 




How many types of COVID-19 variants ?


There are many types :-  Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2) and Delta Plus are the COVID-19 variants.

  • Alpha Variant (B.1.1.7) :- The alpha variant of COVID-19 has caused the most destruction in the country. First identified in UK but which spread to more than 50 countries.
  • Beta Variant (B.1.351) :- There is another dangerous beta variant of coronavirus. First identified in the South Africa but which has been detected in at least 20 other countries, including UK. Beta variant has strong ability to spread infection. even in many cases the vaccine had no effect on this variant. 
  • Gamma Variant (P.1) :- First identified in Brazil but which has spread to more than other 65 countries, including the UK. Sometimes it spreads rapidly due to its mutation. 
  • Delta Variant (B.1.617.2) :- First identified in India, appears to be spreading quickly in many countries. This variant is responsible for the second wave of COVID-19 in the country.   
  •  Delta Plus Variant :- This variant is considered very dangerous. The Minister of  Health said about this that the spread of this variant is rapid. It is tightly bound to the cells of the lungs. It also reduces the antibody response. 



How do you protect yourself from this coronavirus ?


  • Get vaccinated as soon as it's your turn and follow local guidance on vaccination.
  • Keeping 6 feet of distance between yourself and others when out.
  • Washing your hands frequently ( for at least 20 seconds ) with soap and water, especially after going to the bathroom, before eating, after blowing your nose,, coughing or sneezing.
  • Use an alcohol-based sanitizer with at least 60% alcohol.
  • Wear a properly fitted mask when physical distancing is not possible and in poorly ventilated setting. 
  • Avoiding touching your face ( particularly your eyes, nose and mouth ).
  • Staying home as much as possible, even if you don't feel sick. 
  • Avoid close contact with people who are sick. 
  • Avoid crowds and gatherings of 10 or more people. 
  • If you develop symptoms or test positive for COVID-19, self isolate until you recover. 

Hand Sanitizer



  

Who is most at risk severe illness from COVID-19 ?  


People of any age, even children, can catch COVID-19, but it most commonly affects middle-aged and older adults. The risk of developing dangerous symptoms increase with age, with those who are age 65 and older at the highest risk of serious symptoms. 
Risks are ever higher for older people when they have other health conditions like high blood pressure, heart and lung problems, diabetes, obesity or cancer etc. 

However, anyone can get sick with COVID-19 and become seriously ill or die at any age. 




What are the complications of COVID-19 ?


Complications of COVID-19 include :-
  • Pneumonia 
  • Acute Respiratory Distress Syndrome
  • Cardiac injury 
  • Arrhythmia
  • Septic shock 
  • Liver dysfunction 
  • Acute Kidney Injury 
  • Multi-Organ Failure  



What are some severe consequences of the coronavirus disease ?


The COVID-19 viral strain directly impacts the lungs, reducing its capacity and limiting the intake of oxygen and leading to ARDS ( Acute Respiratory Distress Syndrome ) and pneumonia. it is especially deadly in individuals, who have underlying illness and respiratory illness or both. 



In what condition does COVID-19 survive the longest ?

Coronavirus die very quickly when exposed to the UV light in sunlight. Like other enveloped viruses, SARS-CoV-2 survive longest when the temperature is at room temperature or lower, and when the relative humidity is low <50%.



How long does coronavirus last in the body, air and in the food ?


The novel coronavirus, SARS-CoV-2 is the virus responsible for causing the illness COVID-19, most people who developed COVID-19 symptoms improve without treatment in 2-6 weeks. 
How long the virus lasts in the body depends on the individual and the severity of the illness. CDC advice that people who test positive for COVID-19 should isolate themselves.

CDC stands for The Centers for Disease Control and Prevention. 
  • No Symptoms  :- 10 days after a positive test 
  • Mild or moderate illness :- 10 days after symptoms appear, and after 24 hours with no fever without using medication. 
  • Severe illness :- up to 20 days after symptoms appear 
However, the virus may remain in the body at low levels for up to 3 months after diagnosis. 

The study on surfaces also found that SARS-CoV-2 could survive in aerosol from for 3 hours. An aerosol is a fine mist of liquid suspended in a gas, such as air.

Currently, there is no evidence a person can contract SARS-CoV-2 from food.
The WHO state that coronaviruses need a live animal or human host survive, and they cannot multiply on food packaging surfaces. 
The WHO suggest that washing vegetables and fruits as normal and washing hands thoroughly before eating. 






 

What is Cardiac Axis ? How to determine cardiac axis in ECG/EKG by thumb rule ? ECG Axis Thumb Rule

 Cardiac Axis 


The average direction of spread of the Depolarization wave through the Ventricles as seen from the front is called "cardiac Axis". 

                                  Or 

Cardiac axis describe the overall direction of electrical spread within the heart.


NOTE -  It is usual to decide whether this axis is in a normal direction or not.


Lead aVR and lead II look at the heart from opposite directions. when seen from the front,
The depolarization wave normally spreads through the ventricles from 11 O 'clock' to 5 O 'clock', so the deflection in lead aVR are normally mainly downward -ve and in lead II mainly upward +ve. 


Cardiac Axis





Normal Axis


A normal 11 O 'clock - 5 O' clock axis means that the Depolarizing wave is spreading towards lead I, II and III,
                 and is therefore associated with a predominantly upward deflection in all these leads.


NOTE -  The deflection will be greater in lead II than in lead I and than in lead III. 

Cardiac Normal Axis



Right Axis Deviation 


If the right ventricle become hypertrophied, it has more effect on the QRS complex than the left ventricle and the average depolarization wave the axis will swing towards the right.
                     as a result, the deflection in lead I becomes -ve ( predominantly downward ), because depolarization is spreading away from it,
and the deflection in lead III becomes more +ve ( predominantly upward ), because depolarization is spreading towards it, this called right axis deviation.  


Right Axis Deviation


Left Axis Deviation 


When the left ventricle becomes hypertrophied, it exerts more influence on the QRS complex than the right ventricles. hence the axis may swing to the left,
                    as a result the QRS complex becomes predominantly -ve in lead III, this is called left axis deviation.

NOTE -  Left Axis Deviation  is not significant until the QRS complex deflection is also predominantly negative in lead II.
             although left axis deviation can be due to excess influence of an enlarged left ventricle, in fact this axis change is usually due to a conduction defect rather than to increased bulk of the left ventricle muscle.


Left Axis Deviation


CARDIAC AXIS THUMB RULE





The axis is sometime measured in degree, though this is not clinically particularly useful.

Lead I is taken as looking at the heart from 0°
Lead II from +60°; and Lead III from +120°
Lead aVF from +90°; Lead aVL from -30°; and Lead aVR from -150°.

  • Normal Axis  :-  QRS axis between -30° to +90°
  • Left Axis Deviation  :-  QRS axis less than -30°
  • Right Axis Deviation :-  QRS axis greater than +90°
  • Extreme Axis Deviation :- QRS axis between -90 to 180


Cardiac Axis




Why Worry About The Cardiac Axis ?


Right and Left axis deviation in themselves are seldom significant - 

  • Minor degree occur in tall, thin individuals and in short, fat individual, respectively.
  • The presence of axis deviation should alert you to look for other signs of right and left ventricular hypertrophy.
  • A change in axis to the right may indicate a pulmonary embolus. 
  • A change in axis to the left may indicate a conduction block. 




Example 1.

Right Axis Deviation

According to thumb rule :-
  • ECG show Right Axis Deviation
  • Negative QRS Complex in Lead I
  • Positive QRS Complex in Lead II and aVF. 


Example 2.

Left Axis Deviation

According to thumb rule:-
  • ECG show Left Axis Deviation
  • Positive QRS Complex in Lead I
  • Negative QRS Complex in Lead II and Lead aVF.


Example 3.


Normal Cardiac Axis

According to thumb rule:-
  • ECG show Normal Cardiac Axis
  • Positive QRS Complex in Lead I, II and aVF.




ECG Interpretation (How to read an ECG or EKG ?)


Electrocardiography Basics ( characteristics of P wave QRS complex T wave U wave ST segment PR interval )


Human Circulatory System / Blood Vascular System





ECG Interpretation/ How to read an ECG or EKG/ Characteristics of the normal ECG

 ECG INTERPRETATION BASIC 


An ECG complex represents the electrical events occurring in one cardiac cycle. A complex consists of five waveforms labelled with the letters P, Q, R, S, and T. The middle three letters —Q, R, and S—are referred to as a unit, the QRS complex. ECG tracings represent the conduction of electrical impulses from the atria to the ventricles.

 

 P WAVE 


  • Small, Positive and smooth wave.
  • Always +ve in lead II during sinus rhythm.
  • P wave is virtually always +ve in leads aVL, aVF, I, V4, V5, and V6 and -ve in aVR lead.
  • Frequently biphasic in V1 ( occasionally in V2)  the -ve deflection is normally <1mm.
  • P wave duration should be <0.12 sec.
  • P wave amplitude should be <2.5 mm.

Pathological P wave 

  • Tall Tented  :-  Right Atrial Enlargement
  • Bifid (looks like an M) :- Left Atrial Enlargement


 PR INTERVAL


  • Normal PR Interval :-  3-5 small squares 
                                                  or
                                         120 - 200 milliseconds
                                         ( 0.12 to 0.22 sec )
  • A prolonged PR Interval (<0.22 sec) is consistent with lead Ist degree AV-Block.
  • A shortened PR interval (<0.12 sec) indicate pre-excitation (presence of an accessory pathway this is associated with delta wave).

                                                     
                                                 

 QRS COMPLEX


Normal QRS Complex 
 
Amplitude :-  <3 small squares
Duration    :-    0.08 to 0.10 sec 


Q WAVE 

  • Negative deflection preceding the R wave.
  • < 1 small square wide
  • < 2 small square deep 

Pathological (large) Q wave  

  • Past MI
  • MI with last 6 hours
  
  
R WAVE                 

  • The only Positive deflection
  • Look at leads V1, V2, V3
  • If R wave height is equal to or more than S wave

Pathological is either :-

  • Right Ventricular Hypertrophy (T wave inversion also present)
  • Posterior infarct (normal upright T wave)



S WAVE


  • Look at V1, V2, V3
  • If the deepest S wave > 4 big squares.....
  • Then add it to the large R wave of lead V5 or V6.
  • If total >7 :- Left Ventricular Hypertrophy 

NOTE If S wave height in V1, V2. V3, + R wave height in V5 or V6 = LVH 


                                              
QRS COMPLEX WAVEFORM VARIETY


the various configurations of QRS complexes. 
When documenting the QRS complex, use 
uppercase letters to indicate a wave with a normal or high amplitude (greater than 5 mm) and lowercase letters to indicate a wave with a low amplitude (less than 5 mm). In some instances, a second R wave may appear in a QRS complex. 
This is called R'.


QRS Complex Waveform Variety




ST SEGMENT 


  • The ST Segment is the part of the ECG between the end of the S wave and the start of the T wave.

 ST SEGMENT CHANGES


ST Elevation 
  • Acute MI ( STEMI)
  • Acute Pericarditis 
  • Aneurysm

ST Depression 
  • Acute Ischemia 

ST Segment



T WAVE 


  • Duration :-  0.10 to 0.25
  • Amplitude :-  < 5 mm 
  • Normal T Wave  :-  same direction as corresponding QRS Complex 

Pathological T wave 

  • Inversion  :-  Can be a sign of  :-  Ischemia 
                                                                 Old Infarction 
  • Tall T wave  :-  Hyperkalemia 
                                    Hyper-acute Stage of MI





U WAVE 


  • The U wave is a wave on an ECG that is not always seen.
  • Typically small and by definition, follow the T wave.
  • Represent Repolarization of Purkinje fiber.




10-STEP METHOD ( ECG INTERPRETATION)



STEP 1.  Determine the rhythm 


  • Regular or Irregular 
  • P wave before every QRS Complex (Sinus Rhythm)
  • QRS Complex Interval - Constant 


STEP 2.  Determine the rate 


  • Normal  :-  60 - 100 bpm 
  • Tachycardia :-  > 100 bpm 
  • Bradycardia :-  < 60 bpm 


Calculation Method of Heart Rate 

  • If a patient has a regular heart rhythm their heart rate can be calculated by using the following method:-

Regular Rhythm


Method 1.

Calculate Big Square Boxes between one R-R interval,
Then divide 300 by this number to calculate heart rate. 

Heart Rate ( Calculation Method )

Method 2.

Calculate small square boxes between one R-R interval,
Then divide 1500 by this number to calculate heart rate.

Heart Rate ( Calculation Method )


  • If a patient has a irregular heart rhythm their heart rate can be calculated by using the following method:- 


Irregular Rhythm

Method 1.

6 Second strip method 

Simply count the no. Of complete QRS complex in a 6 second strip. 
Then multiple by 10 in this number to calculate heart rate.


6 Second Strip Method of ECG



STEP 3.  Cardiac Axis 


Cardiac axis describes the overall direction of electrical spread within the heart. 


Normal Axis :-  Positive QRS Complex in Lead I and Lead II / Lead aVF


Right Axis Deviation :-

  • Negative QRS Complex in Lead I
  • Positive QRS Complex in Lead II /Lead aVF


Left Axis Deviation :-

  • Positive QRS Complex in Lead I 
  • Negative QRS Complex in Lead II /Lead aVF

Cardiac Axis Thumb Rule





STEP 4.  Evaluate the P wave


  • Are P wave present ?
  • If so, is each P wave followed by a QRS complex ?
  • Do the P wave look normal ?
  • Check :- Duration, Direction and Shape 
  • If  P waves are absent, is there any atrial activity ?
  1. Sawtooth baseline :- Flutter Waves 
  2. Chaotic baseline :-  Fibrillation Waves 
  3. Flat line :-  No atrial activity at all 


STEP 5.  Determine the duration of the PR Interval 


  • Is the PR Duration a normal 0.12 to 0.20 second ?
  • Is the PR Interval constant ?
  • ( To measure the PR interval, count the small squares between the start of the P wave and the start of the QRS complex, then multiply the number of squares by 0.04 second )



STEP 6.  Determine the duration of the QRS Complex 



  • Is the QRS Complex Duration a normal 0.08 to 0.10 second ?
  • Are all QRS Complexes the same size and shape ?
  • If not, measure each one and describe it individually. 
  • ( To calculate QRS Complex Duration, count the number of small squares between the beginning and end of the QRS complex and multiply this number by 0.04 second. )
  • Does a QRS Complex appear after every P wave ?



STEP 7.  Evaluate the ST Segment 



ST - Elevation 

ST - Elevation is significant when it is greater than 1mm ( 1 small square ) in two or more contiguous limb leads or  >2 mm in two or more chest leads indicate myocardial infarction. 


ST - Depression 

ST - Depression >  0.5 mm in more than and equal to two contiguous leads indicate myocardial ischemia.  

ST Segment Changes




STEP 8.  Evaluate the T Wave 


  • Are T wave present ?
  • Do they all have a normal shape, amplitude and duration?
  • Do they all have the same amplitude ?
  • Do the T waves have the same deflection as the QRS complexes ?



STEP 9.  Evaluate the U Wave


  • U wave are not a common finding. 
  • The U wave is a > 0.5 mm deflection after the T wave best seen in V2 or V3.
  • These become larger the slower the bradycardia.
  • U waves are seen in various electrolyte imbalance. 



STEP 10.  Evaluate any other components 


  • Check for the ectopic beats and other abnormalities.
  • Origin of the rhythm ( for example, sinus node, atrial, AV node or ventricles).
  • Rate Characteristics ( for example, bradycardia or tachycardia ).
  • Rhythm Abnormalities ( for example, Flutter, Fibrillation, Heart Block, Escape rhythm or other arrhythmias ).

               


NORMAL SINUS RHYTHM


Normal Sinus Rhythm


• Regular rhythm
• Normal rate
• A P wave for every QRS complex; all P waves similar in size and shape
• All QRS complexes similar in size and shape
• Normal PR and QT intervals
• Normal (upright and round) T waves




THE EFFECT OF REVERSING THE ELECTRODE ATTACHED IN LEFT AND RIGHT ARMS ( LA and RA)



The effect of reversing the electrode in left and right arms

  • Compare with Normal Sinus Rhythm diagram.
  • Inverted P wave in Lead I.
  • Abnormal QRS complex and T wave in Lead I.
  • Upright T waves in Laed aVR are most unusual.








HUMAN CIRCULATORY SYSTEM/BLOOD VASCULAR SYSTEM

HEART CIRCULATORY SYSTEM

OR 

BLOOD VASCULAR SYSTEM


The study of blood vascular system or circulatory system is called angiology  


The vascular system is made up of the vessels that carry blood and lymph fluid through the body. It's also called the circulatory system. The arteries and veins carry blood all over the body. They send oxygen and nutrients to the body tissues.  

Blood Vascular System

BLOOD VESSELS

Arteries 

Veins

Capillaries

All Layer of Arteries and Veins
Diagram of T.S. of Arteries and T.S. of Veins


Differentiate between arteries and vein 


Difference between Arteries and Veins



CAPILLARIES

They have only one layer i.e. simple squamous endothelium layer. 

Diagram of T.S. of Capillaries



ANATOMY OF HEART


Heart  is a coned shaped hollow structure equal to the size of puzzle fit.

It is a mesodermally derived organ, is situated in the thoracic cavity, in between the two lungs (mediastinum), slightly tilled to the left.

The heart weight between 200 to 425g. 
The lower portion is apex and upper portion is base.

Wall of heart 

1.  Pericardium

2.  Myocardium

3.  Endocardium

Pericardium-- It is a outermost layer of the heart.
Heart is protected by a double walled membranous bag like structure called pericardium.

Pericardium layer of Heart

Myocardium -- Consist of specialized cardiac muscle (involuntary in nature) found only in the heart.

Endocardium -- It consist of flatted epithelial cell and it is continuous with endothelium lining the blood vessels.

Labelled Diagram of Heart


Mammals heart have a four chambers, two small upper chambers called atria and two large lower chambers called ventricles.

Inter-atrial septum wall separate the right and the left atria.
It is a thin muscular layer (wall).

Inter-ventricular septum wall separate the right and left ventricles.
It is a thick muscular wall.

Atrio-ventricualr septum separate the atrium and ventricles of the same side.

Blood Circulation of Heart


AORTIC ARCH



Aortic Arch
The aorta arch is the section of the aorta between the ascending and descending aorta that distribute blood to the head and upper extremities via the brachiocephalic trunk, the left common carotid artery, and the left subclavian artery. 

The aortic arch has 3 major branches.
The brachiocephalic trunk is the first branch of the aortic arch and supplies blood to the right arm and right head and neck.
The left common carotid artery is the second branch of the aortic arch, which supplies blood to the left side of the head and the neck.
The last branch of the aortic arch is the left subclavian artery that distribute blood to the left arm. 




PULMONARY CIRCULATION


The deoxygenated blood pumped into the pulmonary artery is passed on to the lungs (from where the oxygenated blood is carried by the pulmonary veins into the left atrium) this pathway is called pulmonary circulation.

Pulmonary circulation occur only between the heart and lungs. 


SYSTEMIC CIRCULATION


Circulation of blood throughout the body through the arteries, capillaries and veins, which carry oxygenated blood from the left ventricle to various tissue and return venous blood to the right atrium.

Systemic circulation occur between the heart and body. 

Diagram of pulmonary circulation and systemic circulation




CONDUCTION SYSTEM OF HEART


The cardiac conduction system is a group of specialized cardiac muscle cells in the walls of the heart.
That send signals to the heart muscle causing it to contract.

The main components of the cardiac conduction system are the SA Node, AV Node, bundle of his, bundle branches and Purkinje fibers.

Conduction system of heart


Diagram of Conduction system of heart

Diagram of Conduction system of heart


FUNCTION OF SA NODE

(Sino-atrial node) or (Natural pacemaker of heart)


1. The SAN can generate the maximum number of action potential. i.e. 70-75 beats per minute (bpm).

2. It is responsible for initiating and maintaining the rhythmic contractile activity of the heart that's why it is called the natural pacemaker.

NOTE- Our heart normally beats 70-75 times in a minute.
(Average 72 beats per minute)



FUNCTION OF AV NODE


1. The purpose of this structure is to connect the electrical system of the atria and the Ventricles, providing electrical impedance from the atria and an intrinsic pacemaker in its absence.

2. The intrinsic rate of the AV node is 40-60 beats per minute (bpm).










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