Download Ventricular arrhythmias - An

Arrhythmia
prebared by
Waleed Sammody
Mohammad Mansour
Supervised by
Jehad Bani Aodih
Basic Facts
An arrhythmia is an
abnormality or
disturbance in the rate
or rhythm of the
heartbeat.
Arrhythmias are caused by
problems with the heart's electrical
system, such as abnormal formation
of the electrical impulses that begin
heartbeats or by a disruption of the
pattern of conduction of those
impulses.
Because the ventricles are
primarily responsible for
moving blood through the
body, ventricular
arrhythmias are often
more serious than other
arrhythmias.
• CAUSES AND RISK FACTORS
Causes of ventricular arrhythmias
include:
1- Abnormal electrolyte (mineral, such as
potassium and magnesium) levels in the blood
2- Electrocution
3- Heart attack (myocardial
infarction)
4- Unstable angina (chest pain).
5- Scarring resulting from a heart attack
Ventricular arrhythmias include
Premature ventricular
complexes (PVCs), which
are premature heartbeats;
Ventricular tachycardia, an
abnormally fast heartbeat;
and
Ventricular fibrillation, in
which the heart quivers
rather than contracts.
An electrocardiogram of
an episode of sustained
ventricular tachycardia.
Premature ventricular
contraction (PVC):
The ventricles fire an early
impulse which causes the
heart to beat earlier causing
irregularity in the heart
rhythm.
Premature ventricular
contraction
(PVC)
Ventricular Tachycardia
This is a dangerous type of rapid heart rhythm
because it is usually associated with poor
cardiac output (amount of blood ejected out of
the heart)
It results from abnormal tissues in the ventricles
generating a rapid and irregular heart rhythm.
Ventricular Tachycardia
Rate
Rhythm
Ventricular
> 100 bpm
Regular
Atrial
None
P-Wave
Absent
P-R Interval
Absent
QRS Complex
> .10
seconds
Ventricular fibrillation
All output from the heart stops, blood
pressure falls rapidly, and the patient
loses consciousness .
Both ventricular tachycardia and ventricular
fibrillation are considered lethal arrhythmias
Only ventricular fibrillation, is linked to the
clinical term “sudden death.” This rhythm is
not able to support life and will lead to
clinical death if untreated
During ventricular fibrillation the
heart is electrically stimulated
by multiple ectopic sites so that
instead of contracting
rhythmically in one united wave
of depolarization, the muscle
actually fibrillates
WHAT ARE THE SYMPTOMS?
Diminished or irregular
pulse;
Fatigue;
Shortness of breath;
Fainting (syncope);
Low blood pressure;
Chest pain; and
Palpitations (awareness
of one's own heartbeat);
Cardiac arrest.
Ventricular fibrillation
An electrocardiogram reflecting the irregular,
pulseless electrical activity of ventricular
fibrillation
TREATMENT APPROACH
● Many cases of arrhythmias may not
require treatment. Other arrhythmias
can be treated by treating any
underlying heart disease. Treatments
for ventricular arrhythmia includes
•Defibrillation
Medication (beta-blockers
and antiarrhythmic agents);
Radiofrequency catheter
ablation;
Angioplasty; and
Pacemaker implantation.
Heart block, also called
atrioventricular block or A-V block, is
an abnormality of the spread or flow
of electrical activity from the upper
heart chambers, the atria, to the
lower chambers of the heart, the
ventricles.
Atrioventricular block (AVB): the sinus
node may be generating heart beats
causing the atria to contract at a normal
rate, however not every electrical
impulse coming from the atria is being
passed down to the ventricles by the
atrioventricular node due to a block in
conduction. There are various types of
AV block depending upon the
mechanism of block.
Classify heart block based
on the length the delay
First-degree heart block
Heart beat impulses are delayed in the
A-V node, but ultimately reach the
ventricles. Sometimes, first-degree
heart block can eventually lead to other
forms of heart block.
.
In first-degree heart block, the
ECG shows one QRS wave for
every P wave, but the pause is
greater than normal
Second-degree heart block
Heart beat impulses are delayed or blocked in
or around the A-V node, and some of the
impulses fail to reach the ventricles; Seconddegree heart block is further divided into two
sub-types:
Type I second-degree heart block, also called
Mobitz Type I heart block or the Wenckebach
phenomenon.
Type II second-degree heart block, also called
Mobitz Type II block
.
second degree block referred to as
Mobitz I or Wenckebach
Occasionally
sinus impulses will pass
through the AV node at slower and
slower rates until excitation is actually
blocked After that the cycle of delay-delayblock repeats itself
This
phenomenon is a form of second
degree block referred to as Mobitz I or
Wenckebach.
Second-Degree Heart Block: Mobitz I
Mobitz II is another form of seconddegree block
Mobitz
II occurs within the context of a basic
rhythm when a P wave occurs but is not
followed by a QRS. This is a more serious
form of second-degree block as it occurs
without warning
The
basic rhythm would be regular except
for the periods of the block. These occur most
often because there is block below the bundle
of His
The P to P interval is once again regular.
The QRS response, because of the
“dropped beat,” will appear irregular
In second-degree type II block,
notice that the P wave (4th bump)
isn't followed by the QRS wave,
because the ventricles weren't
activated.
Third-degree heart block
Also called complete heart block, each
sinus node impulse is completely
interrupted in the A-V node or beyond,
and the ventricles must generate their
own impulse to contract. Depending on
its cause, third-degree block may be
transient (temporary) or permanent.
When no impulses from the atria excite the
ventricle, a situation of complete block exists
Because they are capable of selfautomaticity, a ventricular rhythm is present

Clearly
this is the most serious form of heart
block as the ventricles are now left on their
own to beat
However, at a rate inherent to the
ventricles the patient’s rhythm will
significantly slow

In addition, the effect of
atrial kick is lost

Third-degree heart block