Arrhythmias

1
Arrhythmias

• Prof.Lammers
• Cardiovascular module/ weeks

2
Definition and causes

• Arrhythmia is abnormal rhythm of the heart.
• The possible causes of arrhythmias are
• Abnormal rhythmicity of the pacemaker
• Shift of the pacemaker to another place in the
  heart
• Block of different parts of the conducting system
• Abnormal pathway of impulses transmission
• Spontaneous generation of spurious impulses in
  all parts of the heart.

3
Types of arrhythmias

• Abnormal sinus rhythm
• Impulse conduction Block
• Premature beats
• Paroxysmal tachycardia
• Fibrillation

4
1.Abnormal sinus rhythm

• Abnormal sinus rhythm is an example of abnormal
  rhythmicity of the pace maker.
• It could result from alteration in the strength
  of the sympathetic and parasympathetic system.
• Abnormal sinus rhythm are
• Tachycardia HRgt100. the possible causes are
  (Increase body temprature, Increase sympathetic
  activity)
• Bradycardia HRlt50. this is normal is athletes to
  allow the heart to fill enough blood before
  pumping it. It could result also from excess
  vagus stimulation

5
2.Impulse conduction block

• Sinoatrial Block the impulses are blocked in the
  SA node before reaching the atrial muscles. This
  will eliminate the P wave.
• Atrioventricular Block is caused when there is
  ischemia, compression or inflammation of the AV
  node or AV bundle.
• Interventricular Block( RBBB or LBBB) in which
  impulses fail to reach part of the heart during
  heart cycle.

6
SA block ( absent P wave)
Right bundle Branch block (RBBB) S wave is lead
I, V6 a prominent R wave in V1
7
Left Bundle branch block S wave in V1 and
prominent R wave in lead I and V6
S wave
8
Types of AV blocks

• 1st degree Blockcharacterized by a delay in the
  conduction from the atrium to the ventricles this
  is presented with Prolonged P-R interval.

QRS
T
QRS
T
QRS
T
P
P
P
Prolonged P-R interval
9
Types of AV blocks

• 2nd Degree Block characterized by slow impulses
  conduction. Sometime the impulses are strong
  enough and sometimes they are not. This is known
  as Dropped beats ( no QRS).
• This type has 2 subclasses
• Mobitz I Progressive elongation of PR interval
  is associated with drop beat.drop beat occur
  after progressive elongation of PR interval
• Mobitz II elongation of PR interval is not
  associated with drop beat.drop beat can occur
  anytime.

10
Progressive elongation of P-R
Mobitz I
Mobitz II
Dropped beat
Dropped beat
11
Types of AV block

• 3rd degree heart block also known as complete
  heart block. Where there is poor impulse
  conduction in the AV node. It is presented in the
  ECG by p wave is disassociated from QRS complex.
  In this case the artial beats could be 100/min
  while the ventricular beats are 40/min

T
12
3.Premature beats

• It is also known as Extra-systole , Ectopic
  beats. In this condition, the heart beats before
  the time of normal contraction.
• The causes of premature beat is Ectopic Foci,
  that could be due to Ischemia, calcification
  plaque, toxic irradiation of AV node or purkinji
  fibers.
• The clinical manifestation of Premature beat is
  pulse deficit.As the ventricles will not be able
  to fill?Cardiac output decreases?peripheral pulse
  is not felt.

13
Types of Premature beats

• Premature Atrial Contraction (APC) when the
  atrium contracts very fast.P waves occur too soon
  and PR interval is very short. The possible
  reason is that the beat originates in the atrium
  some where distance from the SA node.

14
Types of Premature beats

• Premature Junctional beat The beat originate
  from the AV node junction and it is characterized
  by absent P wave

Premature Junctional beat
No P wave
15
Types of premature beats

• Premature ventricular contraction (PVC) abnormal
  QRS complex
• prolonged( wide QRS)
• high voltage (tall QRS)
• T wave opposite the polarity of the QRS Inverted

Prolonged/ high voltage QRS
Premature Ventricular contraction
Inverted T wave
16
4.Paroxysmal tachycardia

• Paroxysmal tachycardia is a rapid rhythmical
  discharge of impulses that spread throughout the
  heart. It is caused by re-entrant circus
  movement.
• Types of paroxysmal tachycardia
• Paroxysmal supraventricular tachycardia
• Paroxysmal ventricular tachycardia

17
Types of paroxysmal tachycardia

• Paroxysmal Supraventricular tachycardia during
  the rapid heart beat, the P wave is either
  inverted or within the QRS complex. The QRS
  complex should be narrow, indicating that the
  impulses are generated in the atrium.

Supraventricular Tachycardia (HR170), no P wave
and a narrow QRS complex
18
Types of paroxysmal tachycardia

• Paroxysmal ventricular tachycardia the impulses
  are generated from the ventricles which will lead
  to abnormal QRS and T waves (QRS is usually wide
  indicating that impulses are generated in the
  ventricles) and absent P wave. This is a serious
  problem because it does not occur unless there
  is a considerable ischemic damage, and it could
  initiate Ventricular fibrillation

Ventricular tachycardia abnormal QRS and absent
T wave
19
5.Fibrillation

• Fibrillation result from cardiac impulses that
  have gone berserk within the muscle?this will
  stimulate a portion of muscles to contract
  other are relaxing ? the impulse will feed-back
  on the same portion of muscle to re-excite them
  over and over
• As a result there will be abnormal coordination
  in the contraction of the muscles.

20
Phenomenon of re-entry circus movement

• Fibrillation result Phenomenon of re-entry circus
  movement. In which there will be re-excitation of
  the cardiac muscles over over.
• For re-excitation to occur, impulses should reach
  the muscle after the end refractory period
• The pathway around the circus is enlarged
  (ex.dilated heart)
• Velocity of conduction is decreased (ex.Block of
  purkinji fibers)
• Refractory period is shorten ( ex. by using some
  drugs)

21
Types of fibrillation

• Ventricular fibrillation the most serious
  arrhythmia which if not stopped in 2-3 minutes by
  cardioversion gtgt fatal.
• The ventricles are not contracting, as a result
  no blood is pumped out of the ventricles The
  patient loses consciousness immediately.
• The ECG pattern is showing a saw tooth shape in
  which there is erratic, chaotic pattern of QRS
  complexes

Saw tooth pattern
22
Types of fibrillation

• Atrial fibrillation The atrium is not
  contraction therefore losses its effect as a
  primer pump to eject the extra 25 of blood to
  the ventricles.
• The ECG is AF is irregularly irregular and there
  is no P wave

23
Atrial flutter

• Is another condition which is caused by circus
  movement in the atria. But it is different from
  atrial fibrillation because the electrical
  impulses travel as a single signal always in ONE
  direction.
• In atrial flutter, when impulses reach the AV
  node they delay there. Therefore, every 2-3 beats
  of the atrium is for 1 beat of the ventricles.
• In the ECG we can see the flutter waves.

Flutter waves, with a very high atrial rate and
low ventricular rate. 2 P waves for 1 QRS
P
P
P
P
P
P
QRS
QRS
QRS