Comparison of the use of central and peripheral pressure waveforms for the optimzation of cardiac resynchronization therapy

Background: In patients with cardiac dyssynchrony, optimization of cardiac resynchronization therapy (CRT) is achieved by ascertaining the atrial-ventricular (AV) and inter-ventricular (VV) delays that give maximum cardiac output (CO). As continuous CO measurements are not readily available, this study assesses the use of the peripheral (radial) and central aortic pressure waveform for optimal AV and VV delay using a haemodynamic model. Methods: The model consisted of left and right heart chambers simulated by time varying elastance (variable capacitors), systemic and pulmonary sections simulated by windkessel segments (resistance, capacitance) and a delay line for the arm. Model parameters were altered to obtain maximal values (optimization criterion) for central and peripheral systolic, diastolic and pulse pressure (cSBP, cDBP, cPP, pSBP, pDBP, pPP) and CO from baseline settings of AV (120 ms) and VV (0 ms) delays. Results: The optimal AV delay was not different for all hemodynamic measures. However, optimal VV delay was significantly different for blood pressure parameters compared to CO (*p<0.001). Conclusions: The study indicates that both peripheral and central pressure parameters give similar results for CRT optimisation for AV and VV delay. However optimization for pressure parameters gives significant differences for VV delay compared to CO. This suggests that the ventricular -vascular coupling is an important parameter to be considered for CRT optimisation.