(1)
Departments of Internal Medicine & Psychiatry, Yale University School of Medicine, New Haven, CT, USA
Many incidental EKG abnormalities may be seen when screening patients before medication initiation or monitoring patients on psychotropic medications. These EKG findings may sometimes need immediate attention or referral to a medical provider for additional workup. To perform this triage, it is important to understand some principles of EKG interpretation.
An EKG should always be interpreted in the context of current symptoms. If EKG is performed for routine screening, as is usually the case in a psychiatric outpatient setting, patient is asymptomatic. This is a key factor in determining whether the patient is experiencing an acute cardiac event. Whenever available, comparison should be made with old EKGs to determine if any change has occurred.
Automated measurements by EKG machines are reliable but have limitations. Also, final clinical interpretation requires other factors such as patient’s clinical status and underlying medical conditions.
Some tips are listed in the following tables to differentiate normal and abnormal EKG tracings:
Comparison of normal and abnormal tracing of individual EKG components
Normal pattern | Conditions associated with abnormalities | |
|---|---|---|
P wave (right followed by left atrial depolarization) (<0.12 s or 3 small boxes wide and <0.25 mV or 2.5 small boxes high) | Notched in limb leads and biphasic in V1 | Widened P wave in right atrial enlargement Tall peaked P wave in left atrial enlargement |
PR interval—from beginning of P to beginning of QRS(atrial depolarization and A–V conduction) (0.12 s or 3 small boxes to 0.2 s or 5 small boxes) | Shorter at high heart rates without other abnormalities | Short PR—WPW syndrome Prolonged PR—AV conduction delay |
QRS —initial negative deflection is Q; first positive deflection is R; negative deflection after R is S (ventricular depolarization) (0.06 s or 1.5 small boxes to 0.1 s or 2.5 small boxes) | R wave progresses in amplitude from V1 to V6 | Widened QRS in bundle branch block Poor R wave progression in conditions that disrupt left ventricular conduction |
ST segment—from end of QRS to beginning of T (between ventricular depolarization and repolarization) | Normally slightly concave; can be rapidly upsloping in tachycardia
Related posts: Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
Get Clinical Tree app for offline access
|
