Normal unipolar variants with special reference to the Q and T waves

Abstract

1. I. Q Waves The width and slurring of the Q wave especially in its downstroke and not the depth has been found by us to be most important in determining an infarction especially when preceded by an inverted P wave. However, if the P is upright, then the Q depth is also important. An inverted P wave in aV L does not exclude a myocardial infarct if followed by a slurred and widened Q wave of 0.04 second or more. We were able to produce all types of cavity Q waves in aV L by using only one subject and taking leads while he assumed various positions and during different respiratory phases. We arrived at the following classification of normal Q waves. 1.1. 1. In Lead aV L: 1.1.1. A. Septal Q 1.1.2. B. Endocardial or cavity Q as seen in vertical hearts. 1.2. 2. In Lead aV F: 1.2.1. A. Septal Q. 1.2.2. B. QS type in a very horizontal heart and when the electrode is perpendicular to initial septal impulse. 1.2.3. C. Cavity Q: Rare case when the apex rotates forward in a vertical heart and Lead aV F faces cavity potential at the atrioventricular groove. 1.3. 3. In Lead aV R. 1.3.1. A. QS Pattern: Lead aV R usually shows a QS pattern except when it picks up an initial R from the septum or free right ventricular wall. 1.4. 4. Precordial Semidirect Leads. 1.4.1. A. Septal Q in left ventricular leads. 1.4.2. B. QS pattern in right ventricular leads in a very horizontal heart and when the electrode is perpendicular to the septal impulse and so does not record an initial R. 1.4.3. C. Deep Q waves in children in left ventricular leads. 2. II. T Wave Pattern, 2.1. 1. In Leads aV L and aV F. 2.1.1. A. Normally, T waves may be flat or inverted in these leads if the R is less than 5 mm. in heighth. However, in cases where the lead faces cavity potential and so reveals an initial Q, other than septal, then no matter how high the R, the T wave may be flat or inverted. 2.1.2. B. Transitional or septal T. If these leads face this area, then the T may be flat or inverted. 2.2. 2. In Lead aV R. 2.2.1. A. Normally, the T is always inverted. If upright, then disease is always present. However, a negative T does not exculde disease. 2.3. 3. Precordial Indirect Leads. The T is usually up, except in children when the right ventricular leads may have inverted T waves.