Welch Allyn Means ECG Physicians Manual for CP Series Electrocardiographs - User Manual - Manual (Page 17)

MEANS Physicians Manual
Welch Allyn
17
2.13 Left ventricular hypertrophy (LVH)
The diagnosis of LVH rests on three types of parameters: voltage, shape, and repolarization.
For each parameter, points are accumulated according to its degree of abnormality. The
higher the score, the higher the overall grading of the LVH. The following gradations are
distinguished, in which severity and probability go together: “consider”, “possible”, “probable”,
“definite”, “pronounced”, and “very pronounced”.
The voltage is determined in both the horizontal and frontal planes, but only the plane with the
highest score will be used in the classification. For the horizontal plane the voltages are
measured in leads V1, V5 and V6. In the frontal plane leads I and II are used. If the voltage in
either plane does not meet the criteria, no further analysis for diagnosing LVH will be done.
In both planes an adjustment has been made for age. At age 35 no correction is applied, at
age 90 a maximal correction of about 6 mm in the precordial measurement and of 3 mm in
the frontal plane is added to the measured voltage. For people younger than 35 years the
adjusted voltage will be lower than the calculated voltage, for older people the opposite
applies.
The shape of the QRS complex is determined in that plane where the highest voltage score is
reached. The main parameters on which the shape score is based are the intrinsicoid
deflection and the sequence of small r waves in the right and tall R waves in the left precordial
leads.
In the category repolarization the program tests for the presence and degree of ST
depression and T negativity in the leads I, II, aVL, aVF, V5, and V6. Strain scores in the
frontal and horizontal planes are determined using the ST slope and the J- and T-wave
amplitudes.