Figure 6-22 A flash flood on a river hits an obstruction. The water must find a way around the obstruction, causing turbulence and slower, abnormal flow.
© Jones & Bartlett Learning.
In electrocardiography, aberrancy relates to electrical impulses that travel along nonestablished pathways in order to depolarize the heart. For example, the atrial and ventricular ectopic focus that we covered above are aberrantly conducted. Another aspect of the term that you will very frequently hear, and the main reason for this section, is when a complex is partially transmitted along the normal electrical pathway and then becomes aberrantly conducted because of some obstruction. Let’s start off this discussion by going into this process in more detail.
Suppose you had a dry riverbed. Suddenly there was a big storm leading to a buildup of water that caused a flash flood. The rising waters would take the path of least resistance which, in this case, would be the dry riverbed (Figure 6-22). Now, suppose a beaver had built a dam across that riverbed at some time in the past. What would happen to the water flow when it hit the beaver dam? The water flow would smash into it and have to flow around the obstruction, taking any route it could. Would the flow around the obstruction be smooth as it would have been in the normal riverbed? No, because the water would have to go over millions of tiny obstacles, constantly change directions depending on elevation, and so forth. That flow creates turbulence. Turbulence, even though it is full of energy, is actually much slower moving than smooth, laminar flow. Let’s recap: The water flows smoothly and faster before the obstruction. Once it meets the obstruction, it needs to find a way around it. That causes a slow, turbulent flow of the water to develop.
Figure 6-22 A flash flood on a river hits an obstruction. The water must find a way around the obstruction, causing turbulence and slower, abnormal flow.
© Jones & Bartlett Learning.
The same process can sometimes occur in the heart (Figure 6-23). The most common scenario is as follows: A normal electrical impulse is traveling down the electrical conduction system. Suddenly it hits an area that is refractory (temporarily unable to transmit the impulse) and it continues on from that spot by direct cell-to-cell transmission. As we saw before when we discussed ectopic foci, direct cell-to-cell transmission of the electrical impulse is slow and leads to aberrant vectors. Slow transmission of the impulse leads to wide complexes. Aberrant vectors lead to morphologic differences in the complexes. So, what we end up with many times is a complex that starts out looking normal and like its neighboring complexes but suddenly there is a shift, and it looks totally different at the end.
Figure 6-23 When the impulse hits an area of refractoriness in the right bundle branch, for example, the impulse is forced to continue by direct cell-to-cell transmission throughout the rest of the right ventricle. This leads to a complex that starts out normal and then ends up with a very bizarre appearance.
© Jones & Bartlett Learning.