Dr. Vivek Iyer | Morning Report | 07/06/2016
Estimation: 220 - (Age) = Maximum Rate of Conduction for an individual down the AV-node *Bypass Tracts won't obey this rule
Posted 07/06/16 01:55:42 PM by Adam Faye
-Short PR-segment, slurred upstroke- WPW Pattern (WPW pathway, but no tachycardia). If, palpitations (thus, tachycardia) is present as well, then it is WPW Syndrome. -Often ECGs in patients with WPW will have q-waves, ST-segment changes, t-wave inversions (re-polarization abnormalities). This arises from the depolarization issue in WPW and does not carry the typical interpretation (ex: q-waves do not indicate old infarct in this scenario).
This so called pseudo-infarction can be seen in up to 2/3 of patients - negatively deflected delta waves in the inferior/anterior leads.
Posted 07/06/16 02:07:30 PM by Adam Faye
Can localize the tract based on ECG morphology.
Type A- For example, if in V1 the delta wave is upright, a RBBB pattern - likely accessory pathway is Left Lateral.
Type B- If LBBB pattern, likely coming from a free wall foci on the R side.
~1/3 of patients with WPW develop afib. Afib can conduct rapidly down the bypass tract and can degenerate into Vfib.
Consider Radiofrequency Ablation- moving away from AV node, length of time to depolarization should increase (further from conduction pathway), however if you find an area where the conduction is faster than expected, may be a tract.
After ablation of tract, adenosine is given. Acts through cGMP, and hyperpolarizes tissue (restores excitability, so allows you to see if bypass tract was just dormant after ablation, but still present).
Recall Amiodarone is a negative inotrope, so if someone is barely maintaining pressures (afib in WPW, with HR of 250) - may become hypotensive with (use with caution in certain circumstances).