By Edwin Lim E & Pugliese R - Sept 04, 2014
"Wolff-Parkinson-White (WPW) syndrome is a congenital cardiac abnormality that manifests itself as a conduction irregularity found between the sinoatrial (SA) and atrioventricular (AV) nodes. In an otherwise healthy heart, electrical conduction begins at the SA node, which is located in the right atrium. An electrical pulse is then sent downward causing the atrium to contract and subsequently reaching the AV node, which acts as the connecting catalyst to allow the electrical pulse to reach the ventricles causing them to contract.1 This pathway is controlled as electrical conduction is regulated by the SA and AV node. However, in a patient with Wolff-Parkinson-White syndrome, there is an extra pathway—also known as the accessory pathway—that allows conduction to occur directly between the atrium and ventricles, bypassing the AV node, thus leading to preexcitation of the ventricles. This preexcitation allows conduction to occur with higher and uncontrolled rates resulting in tachycardias.2 The electrocardiogram (ECG) shows a shortened PR interval and the characteristic “delta wave” which resembles a slurring slow rise of the initial portion of the QRS interval."
- WPW orthodromic tachycardias are treated as SVT with an AVNB (i.e. adenosine, verapamil, beta blockers).
- WPW antidromic tachycardias are treated as VT with procainamide or amiodarone.
- WPW with atrial fibrillation is treated with immediate cardioversion if hemodynamically unstable. Procainamide is a reasonable choice in hemodynamically stable patients."
http://empharmd.blogspot.com.es/2014/09/emergent-treatment-of-arrhythmias.html