Disturbances of Cardiac Rhythm: Tachyarrhythmias. Multiprofessional Critical Care Review Course. 2005

The mechanism of tachyarrhythmias are as follows:  abnormal automaticity – involves impulse generation from cells that are not normally arrythmogenic; tiggered automaticity- is attributable to secondary depolarization that arises during or after repolarization; and reentry – requires the presence of an area of slowed or delayed conduction, an anatomical or functional  separate path of conduction, and unidirectional block.  Sites of reentry include the atria, perinodal tissues, and ventricles. 
  
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For more information on caring for the critically ill and injured patients, the publication Multiprofessional Critical Care Review Course is available for purchase from the Society of Critical Care Medicine. Click here for details or to add to your shopping cart.

Pediatrics

Cardiac Surgery and Postoperative Management. Pediatric Multiprofessional Critical Care Review Course. 2006

It is essential to determine the cardiac rhythm when the patient returns from the operating room.  A 12-lead ECG should be performed as soon as possible, and all caregivers must remain alert to possibility of changes in rhythm.  In the early posyoperative period, maintenance of atrioventricular synchrony is a vital component of maximizing cardiac output and oxygen delivery.  In addition to the ECG, other tools that can be used to determine the cardiac rhythm include the bedside monitor and pacing wires, particularly the atrial wires.  The bedside monitor is the most accessible way to examine cardiac rhythm but may provide the least information.  It is reasonable useful for QRS rate and timing, but the p-waves are occasionally hard to see, particularly at faster rates.  When the p-wave is not clearly seen or suspicion remains, as to the atrial rhythm after examination of the 12-lead ECG, an atrial wire recoding can be used. This is done by connecting one or more surface ECG leads to the temporary atrial pacing wires and allows for amplified p-wave to be recorded directly from the surface of the heart. In practical terms, the right arm lead is removed form the patient and attached to either of the temporary atrial pacing wires. Lead I and lead II then become unipolar atrial leads, with lead III remaining the bipolar surface electrode.   

The most common arrhythmias following congenital heart surgery are: junctional ectopic tachycardia (JET),  heart block, orthodromic reciprocating tachycardia (ORT), atrial flutter (AFL), and ventricular tachycardia (VT).

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For more information on caring for the critically ill and injured patients, the publication Pediatric Multiprofessional Critical Care Review Course is available for purchase from the Society of Critical Care Medicine. Click here for details or to add to your shopping cart.