QRSD Ratio (Bundle Branch Differentiation) Calculator

QRSD Ratio (Bundle Branch Differentiation): Explanation and Clinical Context The QRSD Ratio is a metric used to differentiate types of bundle branch conduction delays on ECG, especially in borderline QRS prolongation cases. It is calculated by dividing the QRS duration (ms) by the square root of the RR interval (ms), providing heart rate–corrected QRS assessment. A QRSD ratio <1.15 is typically considered normal, indicating no significant conduction delay.

Ratios between 1.15–1.30 suggest intermediate conduction slowing, whereas ratios >1.30 indicate a high likelihood of bundle branch differentiation. Clinically, this index helps cardiologists detect subtle intraventricular conduction abnormalities that may not be evident by QRS duration alone and can inform prognosis and management, especially in heart failure or bundle branch–related arrhythmias.