DiseaseDisease of Cardiac of Cardiac SystemSystem

prepared by :prepared by :

Asaad Torkman & Asaad Torkman & Mohammad MosaMohammad Mosa

Electrocardiogram Electrocardiogram (EKG, ECG)(EKG, ECG)

Definition : :

It is electrical activity generated by the It is electrical activity generated by the heart can be measured by an array of heart can be measured by an array of electrodes placed on the body surface.electrodes placed on the body surface.

For standard 12-leads ECG, 10 electrodes For standard 12-leads ECG, 10 electrodes (six on the chest and four on the limbs) are (six on the chest and four on the limbs) are placed on the body. placed on the body.

The 12 Lead ECGThe 12 Lead ECG Each of the 12 leads represents a particular orientation in space, as indicated next paragraph. (RA = right arm, LA = left arm, LF = left foot).

Leads divided to three types.

1- Bipolar limb leads .

2- Augmented unipolar limb leads.Augmented unipolar limb leads.

3- 3- Unipolar (+) chest leads.Unipolar (+) chest leads.

 

Bipolar limb leads (frontal plane): Lead I: RA (-) to LA (+) (Right Left, or lateral)

Lead II: RA (-) to LF (+) (Superior Inferior)

Lead III: LA (-) to LF (+) (Superior Inferior)

  Augmented Augmented unipolar limb leadsunipolar limb leads (frontal plane): (frontal plane):

Lead aVR: RA (+) to Lead aVR: RA (+) to [LA & LF] (-) [LA & LF] (-) (Rightward)(Rightward)

Lead aVL: LA (+) to Lead aVL: LA (+) to [RA & LF] (-) [RA & LF] (-) (Leftward)(Leftward)

Lead aVF: LF (+) to Lead aVF: LF (+) to [RA & LA] (-) (Inferior) [RA & LA] (-) (Inferior)

Leads I,II and VL Leads I,II and VL look at the left look at the left lateral surface of lateral surface of the heart.the heart.

Leads III and VF look Leads III and VF look at the inferior at the inferior surface of the heart.surface of the heart.

Lead VR looks at the Lead VR looks at the right atrium.right atrium.

   Unipolar (+) chest leadsUnipolar (+) chest leads (horizontal plane) (horizontal plane)

 Leads V1, V2, V3: (Posterior Anterior) Leads V1, V2, V3: (Posterior Anterior)

 Leads V4, V5, V6:(Right Left, or  Leads V4, V5, V6:(Right Left, or lateral)lateral)

Leads V1 and V2 Leads V1 and V2 look at the right look at the right ventricles.ventricles.

Leads V3 and V4 Leads V3 and V4 look at the septum look at the septum between the between the ventricles and the ventricles and the anterior wall of the anterior wall of the left ventricle.left ventricle.

Leads V5 and V6 Leads V5 and V6 look at the look at the anterior and lateral anterior and lateral walls of the left walls of the left ventricle.ventricle.

THE CARDIAC THE CARDIAC AXISAXIS

cardiac axiscardiac axis the average the average directions of spread of the directions of spread of the depolarization wave through depolarization wave through the ventricles as seen from the the ventricles as seen from the front.front.

Leads VR and II look at the Leads VR and II look at the heart from opposite directions. heart from opposite directions. Seen from the front , the Seen from the front , the depolarization wave normally depolarization wave normally spreads through the ventricles spreads through the ventricles from 11 o’clock to 5 o’clock ,so from 11 o’clock to 5 o’clock ,so the deflections in lead VR are the deflections in lead VR are normally mainly downward normally mainly downward (negative) and in lead II mainly (negative) and in lead II mainly upward (positive).upward (positive).

The Shape of the ECG : P- wave: Depolarization of the right and left atria.

QRS complex: Depolarization right and left ventricular.

ST-T wave: Ventricular repolarization.

U wave: Origin for this wave is not clear - but probably represents "after depolarisations" in the ventricles.

PR interval: Time interval from onset of atrial depolarization (P wave) to onset of ventricular depolarization (QRS complex). The normal PRI is ,12- ,20 seconds.The normal PRI is ,12- ,20 seconds.

QRS duration: Duration of ventricular muscle depolarization. QRS is normally <,12 seconds.QRS is normally <,12 seconds.

 QT interval: Duration of ventricular depolarization and repolarization.

 RR interval: Duration of ventricular cardiac cycle (an indicator of ventricular rate).

PP interval: Duration of atrial cycle (an indicator of atrial rate)

Heart rate calculationHeart rate calculation

Count the number of large squares between 2 consecutive R Count the number of large squares between 2 consecutive R waves and divide into 300waves and divide into 300

OR memorize this scale OR memorize this scale 1 large squares = 300 bpm1 large squares = 300 bpm 2 large squares =150 bpm2 large squares =150 bpm 3 large squares =100 bpm3 large squares =100 bpm

.

                  Normal Sinus Rhythm   Normal sinus rhythm occurs when the electrical impulse starts at a regular rate and rhythm in the sinus node and travels through the normal conduction pathway.

Normal Sinus RhythmThe rules for this rhythm :The rules for this rhythm :REGURALITYREGURALITY : : The R-R intervals are constant ; the rhythm The R-R intervals are constant ; the rhythm

is regular.is regular.

RATE RATE : : The atrial and ventricular rates are equal ; heart rate The atrial and ventricular rates are equal ; heart rate is between 60 and 100 beats per minute.is between 60 and 100 beats per minute.

P WAVEP WAVE : : The P waves are uniform . There is one P wave in The P waves are uniform . There is one P wave in

front of every QRS complex .front of every QRS complex .

Normal sinusNormal sinus rhythmrhythmPRIPRI : the PR interval measures between 0.12 and 0.20 : the PR interval measures between 0.12 and 0.20 seconds ; the PRI measurement is constant across the strip.seconds ; the PRI measurement is constant across the strip.

QRSQRS : the QRS complex measures less than 0.12 seconds : the QRS complex measures less than 0.12 seconds

Sinus node DysrhythmiasSinus node Dysrhythmias Dysrhythmias are disorders of the formation or conduction (or both) of the electrical

impulse within the heart.

Types of sinus dysrhythmias :

1-SINUS BRADYCARDIA: The rate less 60bpm. Sinus Bradycardia associated with athletic training fainting attacks, hypothermia and

myxoedema heart attack.

Sinus BradycardiaSinus Bradycardia The rules for this rhythm:The rules for this rhythm: REGULARITYREGULARITY:: The R-R intervals are constants the The R-R intervals are constants the

rhythm is regular.rhythm is regular.

RATERATE: The atrial and ventricular rates are equal; heart : The atrial and ventricular rates are equal; heart rate is less than 60 beats per minute.rate is less than 60 beats per minute.

Sinus BradycardiaSinus Bradycardia P-WAVE:P-WAVE: There is a uniform P wave in front of every There is a uniform P wave in front of every

QRS complex.QRS complex.

PRI:PRI: the PR interval measures between .12 and .20 the PR interval measures between .12 and .20 seconds; The PRI measurement is constant across seconds; The PRI measurement is constant across the strip.the strip.

QRS:QRS: The QRS complex measures less than .12 The QRS complex measures less than .12 seconds.seconds.

2-Sinus Tachycardia2-Sinus Tachycardia

Sinus TachycardiaSinus Tachycardia:: The rate above The rate above 100bpm.100bpm.

Sinus tachycardiaSinus tachycardia is associated with is associated with exercise, fear, pain, hemorrhage and exercise, fear, pain, hemorrhage and thyrotoxicosis.thyrotoxicosis.

SINUS TACHYCARDIASINUS TACHYCARDIAThe rules for this rhythm : The rules for this rhythm : REGULARITYREGULARITY : The R-R intervals are constant; the rhythm is : The R-R intervals are constant; the rhythm is regular .regular .

RATERATE : The atrial and ventricular rates are equal ; the heart : The atrial and ventricular rates are equal ; the heart rate is usually 150 -250 beats per minuterate is usually 150 -250 beats per minute QRS QRS : the QRS complex measures less than 0.12 seconds .: the QRS complex measures less than 0.12 seconds .

SINUS TACHYCARDIASINUS TACHYCARDIA P WAVEP WAVE : there is one P wave in front of every QRS : there is one P wave in front of every QRS

complex . The configuration of the P wave will be complex . The configuration of the P wave will be different than that of sinus P wave ; they may be different than that of sinus P wave ; they may be flattened or notched . Because of the rapid rate , flattened or notched . Because of the rapid rate , the P waves can be hidden in the T waves of the the P waves can be hidden in the T waves of the preceding beats.preceding beats.

PRIPRI : the PRI is between 0.12 and 0.20 seconds and : the PRI is between 0.12 and 0.20 seconds and

constant across the strip . The PRI may be difficult constant across the strip . The PRI may be difficult to measure if the P wave is obscured by the T to measure if the P wave is obscured by the T wave .wave .

3-Sinus Arrhythmia

Similar to normal sinus rhythm except that PP and RR intervals are irregular because the SA node discharges at a variable frequency

Atrial DysrhythmiasAtrial Dysrhythmias 1-Premature Atrial complex1-Premature Atrial complex (PAC):(PAC):

The rules for this rhythmThe rules for this rhythm: : REGULARITYREGULARITY:: Since this is a single premature ectopic Since this is a single premature ectopic

beat , it will interrupt the regularity of the underlying beat , it will interrupt the regularity of the underlying rhythm . rhythm .

RATERATE: The overall heart rate will depend on the rate of the : The overall heart rate will depend on the rate of the underlying rhythm .underlying rhythm .

Atrial DysrhythmiasAtrial DysrhythmiasP -WAVEP -WAVE: The P wave of the premature beat will have a : The P wave of the premature beat will have a different morphology than the P waves of the rest of the different morphology than the P waves of the rest of the strip . It may be hidden within the T wave of the preceding strip . It may be hidden within the T wave of the preceding complex. complex.

PRIPRI: The PRI should measure between .12 and .20 seconds , : The PRI should measure between .12 and .20 seconds , but can be prolonged ; the PRI of the ectopic will probably be but can be prolonged ; the PRI of the ectopic will probably be different from the PRI measurements of the other complexes .different from the PRI measurements of the other complexes .

QRSQRS: The QRS complex measurement will be less than0 .12 : The QRS complex measurement will be less than0 .12 seconds.seconds.

2-Atrial fibrillation2-Atrial fibrillation This is a result of many sites within the atria firing electrical impulses in an irregular fashion causing irregular heart rhythm. The rules for this rhythm: The rules for this rhythm:

RARATE:TE: The atrial rate cannot be measured because its so chronic ; The atrial rate cannot be measured because its so chronic ; research indicates that it exceeds 350 beats per minute.research indicates that it exceeds 350 beats per minute.

P-WAVEP-WAVE: : In this arrhythmia the atria are not depolarizing in an In this arrhythmia the atria are not depolarizing in an effective way ;instead ,they are fibrillating . Thus , no P wave is effective way ;instead ,they are fibrillating . Thus , no P wave is produced .produced .

2-Atrial fibrillation2-Atrial fibrillationPRIPRI: Since no P waves are visible , no PRI can be measured .: Since no P waves are visible , no PRI can be measured .

REGULARITYREGULARITY: The atrial rhythm is immeasurable; all atrial : The atrial rhythm is immeasurable; all atrial activity is chaotic . The ventricular rhythm is grossly activity is chaotic . The ventricular rhythm is grossly irregular, having no pattern to its irregularity .irregular, having no pattern to its irregularity .

QRSQRS: The QRS complex measurements should be less : The QRS complex measurements should be less than .12 seconds.than .12 seconds.

3-Atrial Flutter3-Atrial Flutter

Atrial Flutter:    In this abnormal rapid heart rhythm the abnormal tissue In this abnormal rapid heart rhythm the abnormal tissue generating the rapid heart rate is also in the atria, however, the generating the rapid heart rate is also in the atria, however, the atrioventricular node is not involved.atrioventricular node is not involved.

The rules for this rhythmThe rules for this rhythm : :

REGULARITYREGULARITY : : the atrial rhythm is regular .The ventricular rhythm will the atrial rhythm is regular .The ventricular rhythm will be regular if the AV node conducts impulses through in consistent be regular if the AV node conducts impulses through in consistent pattern . If the pattern varies , the ventricular rate will be irregular. pattern . If the pattern varies , the ventricular rate will be irregular.

3-Atrial Flutter3-Atrial FlutterP WAVEP WAVE : When the atria flutter they produce a series of well-defined P : When the atria flutter they produce a series of well-defined P waves . When seen together , these “ flutter “ waves have a saw tooth waves . When seen together , these “ flutter “ waves have a saw tooth appearance.appearance.

RATERATE : Atrial rate is between 250 and 350 beats per minute . : Atrial rate is between 250 and 350 beats per minute .

PRIPRI:: Because of the unusual configuration of the P wave ( flutter wave ) Because of the unusual configuration of the P wave ( flutter wave ) and the proximity of the wave to the QRS complex, it is often impossible and the proximity of the wave to the QRS complex, it is often impossible to determine a PRI in this arrhythmia . Therefore , the PRI is not measured to determine a PRI in this arrhythmia . Therefore , the PRI is not measured in atrial flutter .in atrial flutter .

QRSQRS : : The QRS complex measures less than 0.12 seconds. The QRS complex measures less than 0.12 seconds.