Wolff-Parkinson-White Syndrome Pathophysiology, Pre-Excitation and AVRT, Animation

Wolff-Parkinson-White Syndrome Pathophysiology, Pre-Excitation and AVRT, Animation


wolff-parkinson-white or WPW syndrome is
a congenital heart disease characterized by presence of an abnormal electrical
connection between the atria and ventricles of the heart WPW typical
symptom is an abnormally fast heart rate or tachycardia in normal conduction
electrical signals are initiated in the SA node and travel throughout the atria
before they reach the AV node the AV node is the Gateway to the ventricles it
delays the passage of electrical impulses to the ventricles to ensure
that the atria have ejected all the blood into the ventricles before the
ventricles contract this refractory property of the AV node is essential in
limiting electrical activities that reach the ventricles in situations where
the atrial rate is excessively high such as during atrial fibrillation or atrial
flutter the AV node blocks most of the impulses from passing to the ventricles
keeping the heart rate under control in WPW there is an additional connection
between atria and the ventricles called the accessory pathway or bundle of Kent
this pathway is essentially a patch of conductive tissue that provides a
shortcut to the ventricles bypassing the AV node it allows part of electrical
impulses to arrive to the ventricles sooner causing the so called
pre-excitation this can be seen as a shortened PR interval on an ECG because
part of the ventricles depolarized earlier ventricular depolarization
develops in a more gradual fashion and lasts longer resulting in a slurring
slow rise of the initial portion of the QRS complex known as delta wave and QRS
prolongation to note however that the presence of an accessory pathway alone
does not cause tachycardia in fact most people with a WPW pathway never develop
any symptoms they are said to have a WPW pattern as opposed to WPW syndrome in
symptomatic patients there are two mechanisms by which tachycardia can
happen in WPW most commonly tachycardia develops when
electrical impulses traveled down one pathway either the normal or accessory
then back up via the other creating a self-perpetuating loop or a reentrant
circuit the frequency of this loop determines heart rate and can be very
fast ranging from 150 to 250 beats per minute this is known as atrial
ventricular reentry tachycardia or avrt avrt can be orthodontic or antidromic
depending on the direction of the loop another scenario is when WPW patients
also suffer from atrial fibrillation in this condition the atria contract at a
very high rate but most of the electrical impulses do not make it
through the AV node to the ventricles this is where a WPW pathway can have a
detrimental effect it provides a bypass to let more impulses reach the
ventricles causing a faster heart rate that could potentially be fatal
the severity of WPW tachycardia depends on how fast the accessory pathway is
able to conduct this varies from person to person and can be evaluated in a
procedure called programmed electrical stimulation in which the atria are
stimulated to produce progressively higher rates and the atrial to
ventricular conduction ratio is monitored patients are at high risk of
developing lethal tachycardia if their accessory pathway continues to conduct
at a one-to-one ratio with dangerously high atrial rates high risk patients are
usually treated with catheter ablation to destroy the conductive tissue of the
accessory pathway.

10 comments / Add your comment below

  1. Help us make more videos like this! Support us on Patreon and get FREE downloads and other great rewards: https://www.patreon.com/AlilaMedicalMedia/posts

  2. There is a serious lack of information on WPW online. Especially info in laymen’s terms. The animation really helps visualize what exactly is going on in my heart, so thanks for that.

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