Page 187 - Clinical Pearls in Cardiology

Ischemic Heart Disease 175

26. What is meant by poor R wave progression?
The normal ECG shows an RS type complex in lead V1,
with a steady increase in the relative size of the R wave
amplitude and a decrease in the S wave amplitude
towards the left-sided chest leads. The leads V5 and V6
generally show a QR type complex (R wave amplitude in
V5 is often taller than that in V6 because of the attenuating
effect of the lungs). Thus, the QRS complex changes from
predominately negative to predominately positive and
the R/S ratio becomes >1 around the V3 or V4 leads. This
is the transition zone. In some normal individuals, this
transition may be seen as early as lead V2. This is called
early transition. At times, transition may be delayed until
V4 to V5. This is called delayed transition. If the height
of the R wave in leads V1 to V4 remains extremely small,
then ‘‘poor R-wave progression’’ is diagnosed. Poor R
wave progression is frequently caused by relatively high
placement of the mid-precordial leads. Poor R wave
progression may also be associated with a number of
cardiac conditions like the following:
• Anterior wall myocardial infarction.
• Left bundle branch block.
• Wolff-Parkinson-White syndrome.
• Certain types of right ventricular hypertrophy (e.g: in
COPD).
• Left ventricular hypertrophy.
27. What are the causes of tall R wave in lead V1?
The presence of a tall R wave in V1 (i.e. R/S ratio equal to
or greater than 1) is associated with a number of cardiac
conditions like the following:
• Right bundle branch block
• Right ventricular hypertrophy