ARRYTHMIA 2 Flashcards
Atrial flutter
Impulse generation in atrial flutter is much
more regular than in AF. The arrhythmia is
commonly initiated by an ectopic beat which
conducts abnormally through the atria
the characteristic features
of atrial flutter
w P-waves are replaced by regular flutter
waves. These look similar to P-waves in the
right-sided precordial leads (V1–V3), but
in the inferior leads (II, III and aVF) have a
characteristic ‘sawtooth’ pattern
w As described, the rhythm may be regular
or regularly irregular
w As with AF, the QRS is narrow unless
conduction in the ventricles is abnormal.
The initial treatment of atrial flutter is
identical to that
f AF, namely anticoagulation and control of heart rate or rhythm. In
specialist centres, catheter ablation is routinely offered to patients diagnosed with
flutter because the procedure is simpler,
safer and more successful than ablation for
AF
Supraventricular tachycardia
SVT is a rhythm arising above the ventricles with a heart rate
exceeding 100 beats per minute. By this
definition, SVT includes AF, flutter and
even sinus tachycardia
the features that identify
SVT are
w A regular tachycardia, usually between 130 and 250 beats per minute w P-waves are often not seen. Where they are visible on the ECG, they occur after the QRS complex w The QRS complex is narrow, unless ventricular conduction is abnormal
Re-entry describes
a situation where two
distinct pathways of conduction exist, with
different conduction properties. An electrical impulse conducts down one, and then
returns via the other to re-excite the area
that it originated from
In
SVT, re-entry occurs
when the electrical
impulse travels from the atria to the ventricles through the AV node, and is then conducted back into the atria. If the timing is
right, the electrical impulse travels around
this abnormal circuit continuously, causing a
rapid tachycardia
Ventricular tachycardia
VT arises from a site
within the ventricles. It may occur in short
bursts that cause few symptoms, or in a sustained arrhythmia that can cause severe
hypotension, loss of consciousness or cardiac arrest
two types Ventricular tachycardia
monomorphic
polymorphic.
Monomorphic VT
Monomorphic VT is the commonest type, and is most likely to be encountered in clinical practice. Monomorphic means having the same appearance. In monomorphic VT, the QRS complexes all have the same shape
Monomorphic VT
w The rhythm is fast and regular w The QRS complex is wide and bizarre w T-waves are discordant w P-waves do not precede the appearance of QRS complexes w The heart rate can range from 120– 250 beats per minute
Polymorphic VT
the appearance of the
QRS complex is not consistent, but changes
progressively over a number of beats. The
most common cause of polymorphic VT is
QT-interval prolongation, either owing to
drug therapy or inherited long-QT syndrome
Treatment of VT
VT constitutes a
medical emergency and warrants immediate assessment and treatment
If the patient is unresponsive and pulseless,
immediate defibrillation and cardiopulmonary resuscitation (CPR) are indicated (Soar
et al, 2015). Patients who are responsive, but
haemodynamically unstable, may require
DC cardioversion; although stable patients
can be managed with intravenous antiarrhythmic drugs, typically amiodarone
Ventricular fibrillation
no organised rhythm at all.
Electrical activity in the ventricles is chaotic
and rapid. Very rarely, short self-terminating
episodes of VF occur. However, in most
cases, the rhythm is sustained and causes
complete loss of cardiac output, and cardiac
arrest (Bennett, 2013). The cause of VF is
often acute ischaemia owing to coronary
heart disease.
The only
treatment for VF
is immediate defibrillation and CPR (Soar et al, 2015). Survivors
of a VF arrest should be offered an ICD
