@Article{chd.12684,
AUTHOR = {Shankar Baskar, Andrew N. Redington, Philip R. Khoury, Timothy K. Knilans, David S. Spar, Richard J. Czosek},
TITLE = {Ventricular force‐frequency relationships during biventricular or multisite pacing in congenital heart disease},
JOURNAL = {Structural and Congenital Heart Disease},
VOLUME = {14},
YEAR = {2019},
NUMBER = {2},
PAGES = {201--206},
URL = {http://www.techscience.com/schd/v14n2/38754},
ISSN = {3071-1738},
ABSTRACT = {<b>Background:</b> Traditional indices to evaluate biventricular (BiV) pacing are load dependent, fail to 
assess dynamic changes, and may not be appropriate in patients with congenital heart disease 
(CHD). We therefore measured the force‐frequency relationship (FFR) using tissue Doppler‐de‐
rived isovolumic acceleration (IVA) to assess the dynamic adaption of the myocardium and its vari‐
ability with different ventricular pacing strategies.<br/>
<b>Methods:</b> This was a prospective pilot study of pediatric and young adult CHD patients with 
biventricular or multisite pacing systems. Color‐coded myocardial velocities were recorded at 
the base of the systemic ventricular free wall. IVA was calculated at resting heart rate and with
incremental pacing. FFR curves were obtained by plotting IVA against heart rate for different
ventricular pacing strategies.<br/>
<b>Results:</b> Ten patients were included (mean: 22 ± 7 years). The FFR identified a best and worst 
ventricular pacing strategy for each patient, based on the AUC at baseline, submaximal, and
peak heart rates (P < .001). However, there was no single best ventricular pacing strategy that 
was optimal for all patients. Additionally, the best ventricular pacing strategy often differed
within the same patient at different heart rates.<br/>
<b>Conclusion:</b> This novel assessment demonstrates a wide variability in optimal ventricular pac‐
ing strategy. These inherent differences may play a role in the unpredictable clinical response 
to BiV pacing in CHD, and emphasizes an individualized approach. Furthermore, the optimal 
ventricular pacing varies with heart rate within individuals, suggesting that rate‐responsive 
ventricular pacing modulation may be required to optimize ventricular performance.},
DOI = {10.1111/chd.12684}
}