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R Wave

R wave

Limb Leads and R Wave

• Limb leads (I, II, III, aVF, aVR, aVL)
• Look at the heart in the frontal plane
• The ventricles are activated in the order:
1. Ventricular septum (V_S - septal vector)
2. Left and right ventricles (V_M - main vector)
3. Base of the left ventricle (V_T - terminal vector)
• Vector of the ventricular septum (V_S)
• Directed away from leads aVL, I (sometimes also from lead II)
• and creates the Q wave
• Main heart vector (V_M)
• Directed away from lead aVR
• Creates a deep S wave (sometimes a Q wave)
• Directed almost directly towards lead II
• where it creates the highest R wave

R Wave Progression and Transition Zone

• R wave progression means
  • that the amplitude of the R wave increases in the precordial leads from lead V1 to lead V5 (V4)

R Wave Progression and Transition Zone

• Main heart vector
• Directly points to lead V4 (V5)
• therefore, in these leads, the R wave is the highest
• It is perpendicular to V3
• therefore, in lead V3, there is a positive-negative RS wave
• RS wave (amplitude R = S)
  • is referred to as the transition zone and informs us about the heart's rotation along the longitudinal axis

Variants of the R Wave

Nomenclature of the QRS Complex

• Uppercase letters (Q, R, S) denote the dominant waves of the QRS complex
• Lowercase letters (q, r, s) denote waves that are smaller than 1/2 of the dominant wave of the QRS complex
• The Q wave is the first negative wave of the QRS complex
• The QS wave is an entirely negative QRS complex
• The R wave is any positive wave; if there are 2 positive waves in the QRS complex, the second one is denoted with an apostrophe (')

Physiological R Wave

Sinus Rhythm

• Sinus Rhythm and physiological R wave
• R wave height in limb leads ≤ 10mm (I, II, III, aVL, aVR, aVR)
• R wave height in chest leads ≤ 25mm (V1-V6)
• R wave progression from V1 to V4
• In leads aVR and V1, the QRS complex is predominantly negative
• Because the main heart vector is directed away from these leads (aVR, V1)
• The height of the R waves does not change (no presence of QRS alternans)
• The transition zone is V2/V3 (the heart is slightly rotated counterclockwise)
• QRS is predominantly negative in lead V2, and predominantly positive in lead V3
• The transition zone is between V2 and V3, designated as V2/V3

Dominant R Wave in V1

Right Bundle Branch Block

• In V1, there is a qR configuration (Dominant R Wave in V1)
• Dominant R Wave in V1 requires increased attention
• It is a right bundle branch block
• Wide QRS complex > 0.12s
• Dominant QRS in V1 (qR configuration)
• Deep S in V6
• Why is R dominant in V1?
• The right bundle branch is blocked
• The impulse through the left bundle branch activates the left ventricle
• and then activates the right ventricle from the left ventricle, vector points towards V1

Decreased R Wave Progression (Amputated R in V1-V4)

Old Antero-Septal Infarction

• Decreased R Wave Progression (amputated R in V1-V4)
• R wave in leads V1-V3 does not increase, but a deep Q wave is present
• Pathological Q wave (Q wave in leads V1-V3 is always considered pathological)
• On the ECG, there is an old antero-septal infarction
• Pathological Q (V1-V4)
• Negative T wave (V1-V5)
• Why is there decreased R wave progression?
• Because there is a scar on the anterior wall from the infarction (electrical window)
• All leads above the electrical window create a pathological Q wave
• And no R wave is generated