Chapter 9 Flashcards
P waves are normally positive in
I II V4 V5 V6
P waves are normally negative in
aVR
Normal conduction of the impulse from the SA to the AV takes place through
Specialized conduction fibres known as the anterior, middle and posterior internodal pathways
The bachmann bundle is
An internodal pathway connecting the two atria
Non compensatory pause
The sinus node is depolarized. The distance of the next P-P interval will be less than 2x seconds
Inverted p-waves in II III and aVF, positive p-waves in aVL and a PRI GREATER than 0.11 seconds is likely
Low atrial ectopic pacemaker. A junctional pacer is also possible, but more likely if the PRI is shortened
P-mitrale
P wave greater than 0.12 seconds in I and II, and notched. The space between the two humps should be greater than 0.04 seconds. It is caused because of the prolonged conduction time required to transmit through the enlarged left atrium.
Causes of p-mitrale
Severe mitral valve disease. Mitral stenosis leads to LAE by increasing the muscle mass needed to overpower the stenotic valve. Enlargement occurs when the muscle dilates in order to compensate for the additional blood volume.
P-pulmonale
Peaked P wave more than 2.5mm high in limb leads. Most common and prominent in leads II and III. Indicates RAE.
When you see different P wave morphologies
Measure the PRI
Intraatrial conduction delay (IACD)
When there is a non specific atrial conduction problem, but not enough evidence to call it enlargement. It is a biphasic p wave in V1
Evidence of RAE in IACD
When the first half of the biphasic p wave in V1 is taller than the first half of the p in V6, RAE is likely
Evidence of LAE in IACD
When the second half of the biphasic P wave is wider and deeper than 0.04 seconds LAE is likely.
If the product of the height times width of the second half of the biphasic p wave is 0.03 or greater, LAE is 95% likely
Causes of RAE
COPD, pulmonary emboli, pulmonary hypertension, mitral, tricuspid or pulmonary valve disease
Causes of LAE
Severe systemic hypertension, aortic or mitral valve disease, restrictive cardiomyopathy, and LV failure. (Anything that obstructs forward flow such as defective valves or still LV)
