If there is no R wave, the combined negative deflection is called a ______ waves.

If there is no R wave, the combined negative deflection is called a ______ waves.

• A. QS waves
• B. Q waves
• C. S waves
• D. R waves

Answer: (A)

When the QRS complex depolarizes away from the positive lead so that no positive R wave appears, the negative deflections that remain come from the initial Q and the following S, giving a QS pattern. This is why the correct term is QS waves: the sequence lacks the positive R deflection, leaving a combined negative deflection that is described as QS. Calling it Q waves isn’t accurate here because there’s no subsequent R to define a Q wave before it; calling S waves isn’t right because S is the negative deflection after R, which isn’t present. R waves are the positive components that are absent in this scenario.

When the QRS complex depolarizes away from the positive lead so that no positive R wave appears, the negative deflections that remain come from the initial Q and the following S, giving a QS pattern. This is why the correct term is QS waves: the sequence lacks the positive R deflection, leaving a combined negative deflection that is described as QS. Calling it Q waves isn’t accurate here because there’s no subsequent R to define a Q wave before it; calling S waves isn’t right because S is the negative deflection after R, which isn’t present. R waves are the positive components that are absent in this scenario.