What is the significance of an R wave during diastole (diastolic period)?

R Wave During Diastole: Clinical Significance

Direct Answer

The R wave measured at peak diastole (end-diastole) is a critical timing reference point for assessing diastolic flow reversal in aortic regurgitation, where end-diastolic velocity >20 cm/s in the descending aorta indicates severe disease. 1

Primary Clinical Context: Aortic Regurgitation Assessment

The most clinically significant use of "R wave diastolic" terminology refers to timing measurements at the peak R wave on ECG, which marks end-diastole, particularly when evaluating aortic regurgitation (AR) severity. 1

Key Measurement Technique

• Diastolic flow reversal in the descending aorta should be measured at the peak R wave (end-diastole) using pulsed-wave Doppler from a suprasternal view 1
• The sample volume is placed just distal to the left subclavian artery origin at the aortic isthmus level 1
• Doppler filter must be decreased to lowest setting to detect low velocities (<10 cm/s) 1

Severity Grading Criteria

End-diastolic velocity measured at peak R wave ≥20 cm/s indicates severe aortic regurgitation when sustained throughout diastole in the proximal descending aorta. 1 This represents one of the strongest additional parameters for AR severity assessment. 1

• Mild AR: Brief early diastolic flow reversal only 1
• Progressive AR: Increasing duration and velocity of reversal flow 1
• Severe AR: Holodiastolic reversal at velocities >20 cm/s at end-diastole (R wave peak) 1

Secondary Clinical Context: Diastolic Function Assessment

The R wave serves as a standardized timing reference for multiple diastolic measurements in echocardiography. 1

Timing Applications

• Measurements should be performed at end-diastole (R wave on ECG) to ensure consistency across cardiac cycles 1
• The time interval between peak R wave and onset of mitral E velocity (TE-e') helps assess diastolic function 1
• Pulmonary vein atrial reversal (AR) duration is measured from AR-wave onset to end at zero baseline 1

Technical Considerations

All Doppler and M-mode recordings should be acquired at 100 mm/sec sweep speed with measurements at the R wave to identify end-diastole. 1 This standardization reduces variability in diastolic function assessment. 1

Clinical Pitfalls to Avoid

• Do not confuse "R wave diastolic" with R wave progression abnormalities (poor R wave progression or reversed R wave progression), which are entirely different ECG findings related to ventricular depolarization patterns, not timing references 2, 3
• Ensure proper Doppler alignment when measuring diastolic flow reversal, as beam misalignment causes significant measurement errors 1
• The cut-off value of 20 cm/s for severe AR has been validated specifically in the proximal descending aorta just beneath the aortic isthmus, not other locations 1