Measurement of QRS Duration for Biventricular Pacing Optimization

Abstract

Optimization of left ventricular pacing site (LVPS) or interventricular pacing delay (VVD) improves the efficacy of biventricular pacing (BiVP). Cardiac output (CO) based optimization, however, is invasive and slow. QRS duration (QRSd) is non-invasive and responds rapidly. Accordingly, we investigated the utility of QRSd for BiVP optimization in a model of acute right ventricular (RV) pressure overload. In 7 anesthetized open-chest pigs, BiVP was implemented with right atrial and RV pacing wires. A 6-electrode array was placed behind the LV. Heart block was established by alcohol ablation. The pulmonary artery was snared to double peak RV pressure. Fifty-four combinations of LVPS and VVD were tested in random order over 30 sec intervals. QRSd was assessed from ECG lead II, CO from aortic flow probe, and ventricular function from micromanometers. Comparisons were made with the Pearson’s correlation coefficient (r). QRSd narrowing was associated with improved RV function and transseptal synchrony, but correlation with CO was poor. Additionally, QRSd averaged over the last 20 cardiac cycles in each interval was compared to values averaged over successive cardiac cycles following each reprogramming. Seven cardiac cycles after reprogramming, the average r-value went above 0.90 and plateaued. QRSd-based optimization merits further study during BiVP in patients with congestive heart failure.

Relation of QRS Shortening to Cardiac Output During Temporary Resynchronization Therapy After Cardiac Surgery

“…QRSd was also examined in this model. 28 In an aortic insufficiency model, we find LV-first pacing promotes transseptal synchrony and maximizes LVdp/dt. 23 These studies support the view that VVD optimization is affected by the pathophysiology and ventricular dependence of the underlying heart failure.…”

“…27 A more expeditious index would reduce the time required, and possibly promote automated optimization. Our laboratory has demonstrated potential utility of QRSd for intraoperative CRT optimization in animals, 28 and the utility of QRSd for VVD optimization in patients during CRT was recently endorsed. 26 Accordingly, we correlated QRSd with CO during VVD optimization for temporary CRT after OHS.…”