The time it takes for peak voltage to develop within the ventricles, measured from the onset of the QRS to the peak of the R wave, is the ________ deflection. A prolonged version (>0.06 s) is considered a late R wave.

The time it takes for peak voltage to develop within the ventricles, measured from the onset of the QRS to the peak of the R wave, is the ________ deflection. A prolonged version (>0.06 s) is considered a late R wave.

• A. Intrinsicoid deflection
• B. QRS duration
• C. PR interval
• D. ST segment

Answer: (A)

This question is about intrinsicoid deflection, also called the R wave peak time. It’s the interval from the start of ventricular depolarization (the beginning of the QRS complex) to the moment the R wave reaches its peak in a given lead. This measure tells us how quickly the depolarization wavefront reaches the region of the ventricle beneath that lead, essentially how fast the ventricle activates in that area. In a healthy heart the intrinsicoid deflection is relatively short. When it lengthens beyond about 0.06 seconds, we call it a late R wave, indicating delayed activation of part of the ventricle—often due to left ventricular conduction delay or hypertrophy affecting the left ventricle. The other intervals refer to different aspects of conduction or repolarization: the QRS duration is the total time of ventricular depolarization, the PR interval is the AV conduction time from atrial to ventricular activation, and the ST segment is the flat portion between depolarization and repolarization—not the time to peak R.

This question is about intrinsicoid deflection, also called the R wave peak time. It’s the interval from the start of ventricular depolarization (the beginning of the QRS complex) to the moment the R wave reaches its peak in a given lead. This measure tells us how quickly the depolarization wavefront reaches the region of the ventricle beneath that lead, essentially how fast the ventricle activates in that area.

In a healthy heart the intrinsicoid deflection is relatively short. When it lengthens beyond about 0.06 seconds, we call it a late R wave, indicating delayed activation of part of the ventricle—often due to left ventricular conduction delay or hypertrophy affecting the left ventricle.

The other intervals refer to different aspects of conduction or repolarization: the QRS duration is the total time of ventricular depolarization, the PR interval is the AV conduction time from atrial to ventricular activation, and the ST segment is the flat portion between depolarization and repolarization—not the time to peak R.